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Sample records for alkali metal alloy

  1. 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.

  2. 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.

  3. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C.; Morgan, Michael J.

    1986-02-04

    A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

  4. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  5. Methods of recovering alkali metals

    DOEpatents

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

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

  6. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

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

    2015-04-07

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

  7. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    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 from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  8. The electronic properties of bare and alkali metal adsorbed two-dimensional GeSi alloy sheet

    NASA Astrophysics Data System (ADS)

    Qiu, Wenhao; Ye, Han; Yu, Zhongyuan; Liu, Yumin

    2016-09-01

    In this paper, the structural and electronic properties of both bare and alkali metal (AM) atoms adsorbed two-dimensional GeSi alloy sheet (GeSiAS) are investigated by means of first-principles calculations. The band gaps of bare GeSiAS are shown slightly opened at Dirac point with the energy dispersion remain linear due to the spin-orbit coupling effect at all concentrations of Ge atoms. For metal adsorption, AM atoms (including Li, Na and K) prefer to occupy the hexagonal hollow site of GeSiAS and the primary chemical bond between AM adatom and GeSiAS is ionic. The adsorption energy has an increase tendency with the increase of the Ge concentration in supercell. Besides, single-side adsorption of AM atoms introduces band gap at Dirac point, which can be tuned by the Ge concentration and the species of AM atoms. The strong relation between the band gaps and the distribution of Si and Ge atoms inside GeSiAS are also demonstrated. The opened band gaps of AM covered GeSiAS range from 14.8 to 269.1 meV along with the effective masses of electrons ranging from 0.013 to 0.109 me, indicating the high tunability of band gap as well as high mobility of carriers. These results provide a development in two-dimensional alloys and show potential applications in novel micro/nano-electronic devices.

  9. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  10. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

    A process is described of recovering alkali metal vapor by sorption on activated alumina, activated carbon, dehydrated zeolite, activated magnesia, or Fuller's earth preheated above the vaporization temperature of the alkali metal and subsequent desorption by heating the solvent under vacuum. (AEC)

  11. Upgrading platform using alkali metals

    SciTech Connect

    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.

  12. Apparatus enables accurate determination of alkali oxides in alkali metals

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.; Gahn, R. F.; Graab, J. W.; Maple, W. E.; Rosenblum, L.

    1966-01-01

    Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure.

  13. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

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

    2016-08-02

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

  14. Method for the safe disposal of alkali metal

    DOEpatents

    Johnson, Terry R.

    1977-01-01

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

  15. Removal of Retired Alkali Metal Test Systems

    SciTech Connect

    Brehm, W. F.; Church, W. R.; Biglin, J. W.

    2003-02-26

    This paper describes the successful effort to remove alkali metals, alkali metal residues, and piping and structures from retired non-radioactive test systems on the Hanford Site. These test systems were used between 1965 and 1982 to support the Fast Flux Test Facility and the Liquid Metal Fast Breeder Reactor Program. A considerable volume of sodium and sodium-potassium alloy (NaK) was successfully recycled to the commercial sector; structural material and electrical material such as wiring was also recycled. Innovative techniques were used to safely remove NaK and its residues from a test system that could not be gravity-drained. The work was done safely, with no environmental issues or significant schedule delays.

  16. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

    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 from the particles primarily in the form of water soluble alkali metal formates by treating the particles with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of added carbon monoxide. During the treating process the water insoluble alkali metal compounds comprising the insoluble alkali metal residues are converted into water soluble alkali metal formates. The resultant aqueous solution containing water soluble alkali metal formates is then separated from the treated particles and any insoluble materials formed during the treatment process, and recycled to the gasification process where the alkali metal formates serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. This process permits increased recovery of alkali metal constituents, thereby decreasing the overall cost of the gasification process by reducing the amount of makeup alkali metal compounds necessary.

  17. Alkali and transition metal phospholides

    NASA Astrophysics Data System (ADS)

    Bezkishko, I. A.; Zagidullin, A. A.; Milyukov, V. A.; Sinyashin, O. G.

    2014-06-01

    Major tendencies in modern chemistry of alkali and transition metal phospholides (phosphacyclopentadienides) are systematized, analyzed and generalized. Basic methods of synthesis of these compounds are presented. Their chemical properties are considered with a special focus on their complexing ability. Potential applications of phospholides and their derivatives are discussed. The bibliography includes 184 references.

  18. Surface modification by alkali and heat treatments in titanium alloys.

    PubMed

    Lee, Baek-Hee; Do Kim, Young; Shin, Ji Hoon; Hwan Lee, Kyu

    2002-09-01

    Pure titanium and titanium alloys are normally used for orthopedic and dental prostheses. Nevertheless, their chemical, biological, and mechanical properties still can be improved by the development of new preparation technologies. This has been the limiting factor for these metals to show low affinity to living bone. The purpose of this study is to improve the bone-bonding ability between titanium alloys and living bone through a chemically activated process and a thermally activated one. Two kinds of titanium alloys, a newly designed Ti-In-Nb-Ta alloy and a commercially available Ti-6Al-4V ELI alloy, were used in this study. In this study, surface modification of the titanium alloys by alkali and heat treatments (AHT), alkali treated in 5.0M NaOH solution, and heat treated in vacuum furnace at 600 degrees C, is reported. After AHT, the effects of the AHT on the bone integration property were evaluated in vitro. Surface morphologies of AHT were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Chemical compositional surface changes were investigated by X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). Titanium alloys with surface modification by AHT showed improved bioactive behavior, and the Ti-In-Nb-Ta alloy had better bioactivity than the Ti-6Al-4V ELI alloy in vitro.

  19. 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.

  20. Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides

    DOEpatents

    Gordon, John Howard; Alvare, Javier

    2016-10-25

    Alkali metals and sulfur may be recovered from alkali monosulfide and polysulfides in an electrolytic process that utilizes an electrolytic cell having an alkali ion conductive membrane. An anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof and a solvent that dissolves elemental sulfur. A catholyte includes molten alkali metal. Applying an electric current oxidizes sulfide and polysulfide in the anolyte compartment, causes alkali metal ions to pass through the alkali ion conductive membrane to the catholyte compartment, and reduces the alkali metal ions in the catholyte compartment. Liquid sulfur separates from the anolyte solution and may be recovered. The electrolytic cell is operated at a temperature where the formed alkali metal and sulfur are molten.

  1. Alkali-Metal Spin Maser.

    PubMed

    Chalupczak, W; Josephs-Franks, P

    2015-07-17

    Quantum measurement is a combination of a read-out and a perturbation of the quantum system. We explore the nonlinear spin dynamics generated by a linearly polarized probe beam in a continuous measurement of the collective spin state in a thermal alkali-metal atomic sample. We demonstrate that the probe-beam-driven perturbation leads, in the presence of indirect pumping, to complete polarization of the sample and macroscopic coherent spin oscillations. As a consequence of the former we report observation of spectral profiles free from collisional broadening. Nonlinear dynamics is studied through exploring its effect on radio frequency as well as spin noise spectra. PMID:26230788

  2. Alkali-Metal Spin Maser

    NASA Astrophysics Data System (ADS)

    Chalupczak, W.; Josephs-Franks, P.

    2015-07-01

    Quantum measurement is a combination of a read-out and a perturbation of the quantum system. We explore the nonlinear spin dynamics generated by a linearly polarized probe beam in a continuous measurement of the collective spin state in a thermal alkali-metal atomic sample. We demonstrate that the probe-beam-driven perturbation leads, in the presence of indirect pumping, to complete polarization of the sample and macroscopic coherent spin oscillations. As a consequence of the former we report observation of spectral profiles free from collisional broadening. Nonlinear dynamics is studied through exploring its effect on radio frequency as well as spin noise spectra.

  3. Heat pipes containing alkali metal working fluid

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1981-01-01

    A technique for improving high temperature evaporation-condensation heat-transfer devices which have important and unique advantage in terrestrial and space energy processing is described. The device is in the form of a heat pipe comprising a sealed container or envelope which contains a capillary wick. The temperature of one end of the heat pipe is raised by the input of heat from an external heat source which is extremely hot and corrosive. A working fluid of a corrosive alkali metal, such as lithium, sodium, or potassium transfers this heat to a heat receiver remote from the heat source. The container and wick are fabricated from a superalloy containing a small percentage of a corrosion inhibiting or gettering element. Lanthanum, scandium, yttrium, thorium, and hafnium are utilized as the alloying metal.

  4. The alkali metals: 200 years of surprises.

    PubMed

    Dye, James L

    2015-03-13

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

  5. The alkali metals: 200 years of surprises.

    PubMed

    Dye, James L

    2015-03-13

    Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides! PMID:25666067

  6. 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.

  7. 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.

  8. 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.

  9. Chemical compatibility of structural materials in alkali metals

    SciTech Connect

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

    1995-04-01

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

  10. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  11. 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.

  12. Procedural analysis of a new method for determining the Gibbs energy and experimental data on thermodynamic properties of liquid-metal coolants based on alkali metal alloys

    SciTech Connect

    Kagan, D. N. Krechetova, G. A.; Shpil'rain, E. E.

    2010-12-15

    A detailed procedural analysis is given and results of implementation of the new version of the effusion method for determining the Gibbs energy (thermodynamic activity) of binary and ternary systems of alkali metals Cs-Na, K-Na, Cs-K, and Cs-K-Na are presented. The activity is determined using partial pressures of the components measured according the effusion method by the intensity of their atomic beams. The pressure range used in the experiment is intermediate between the Knudsen and hydrodynamic effusion modes. A generalized version of the effusion method involves the pressure range beyond the limits of the applicability of the Hertz-Knudsen equation. Employment of this method provides the differential equation of chemical thermodynamics; solution of this equation makes it possible to construct the Gibbs energy in the range of temperatures 400 {<=} T {<=} 1200 K and concentrations 0 {<=} x{sub i} {<=} 1.

  13. Alkali Metal Salts with Designable Aryltrifluoroborate Anions.

    PubMed

    Iwasaki, Kazuki; Yoshii, Kazuki; Tsuzuki, Seiji; Matsumoto, Hajime; Tsuda, Tetsuya; Kuwabata, Susumu

    2016-09-01

    Aryltrifluoroborate ([ArBF3](-)) has a designable basic anion structure. Various [ArBF3](-)-based anions were synthesized to create novel alkali metal salts using a simple and safe process. Nearly 40 novel alkali metal salts were successfully obtained, and their physicochemical characteristics, particularly their thermal properties, were elucidated. These salts have lower melting points than those of simple inorganic alkali halide salts, such as KCl and LiCl, because of the weaker interactions between the alkali metal cations and the [ArBF3](-) anions and the anions' larger entropy. Moreover, interestingly, potassium cations were electrochemically reduced in the potassium (meta-ethoxyphenyl)trifluoroborate (K[m-OEtC6H4BF3]) molten salt at 433 K. These findings contribute substantially to furthering molten salt chemistry, ionic liquid chemistry, and electrochemistry. PMID:27510799

  14. 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.

  15. 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.

  16. 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.

  17. Cohesive Energy of the Alkali Metals.

    ERIC Educational Resources Information Center

    Poole, R. T.

    1980-01-01

    Describes a method, considered appropriate for presentation to undergraduate students in materials science and related courses, for the calculation of cohesive energies of the alkali metals. Uses a description based on the free electron model and gives results to within 0.1 eV of the experimental values. (Author/GS)

  18. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  19. 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...

  20. 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...

  1. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

  2. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

  3. 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... 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)...

  4. 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)...

  5. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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)...

  6. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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)...

  7. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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)...

  8. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  9. Alkali metal recovery from carbonaceous material conversion process

    DOEpatents

    Sharp, David W.; Clavenna, LeRoy R.; Gorbaty, Martin L.; Tsou, Joe M.

    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 in the gasifier or similar reaction zone, alkali metal constitutents are recovered from the particles by withdrawing and passing the particles from the reaction zone to an alkali metal recovery zone in the substantial absence of molecular oxygen and treating the particles in the recovery zone with water or an aqueous solution in the substantial absence of molecular oxygen. The solution formed by treating the particles in the recovery zone will contain water-soluble alkali metal constituents and is 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. Preventing contact of the particles with oxygen as they are withdrawn from the reaction zone and during treatment in the recovery zone avoids the formation of undesirable alkali metal constituents in the aqueous solution produced in the recovery zone and insures maximum recovery of water-soluble alkali metal constituents from the alkali metal residues.

  10. 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.

  11. Alkali Metal Heat Pipe Life Issues

    SciTech Connect

    Reid, Robert S.

    2004-07-01

    One approach to fission power system design uses alkali metal heat pipes for the core primary heat-transfer system. Heat pipes may also be used as radiator elements or auxiliary thermal control elements. This synopsis characterizes long-life core heat pipes. References are included where information that is more detailed can be found. Specifics shown here are for demonstration purposes and do not necessarily reflect current Nasa Project Prometheus point designs. (author)

  12. 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.

  13. 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.

  14. Metal induced gap states at alkali halide/metal interface

    NASA Astrophysics Data System (ADS)

    Kiguchi, Manabu; Yoshikawa, Genki; Ikeda, Susumu; Saiki, Koichiro

    2004-10-01

    The electronic state of a KCl/Cu(0 0 1) interface was investigated using the Cl K-edge near-edge X-ray absorption fine structure (NEXAFS). A pre-peak observed on the bulk edge onset of thin KCl films has a similar feature to the peak at a LiCl/Cu(0 0 1) interface, which originates from the metal induced gap state (MIGS). The present result indicates that the MIGS is formed universally at alkali halide/metal interfaces. The decay length of MIGS to an insulator differs from each other, mainly due to the difference in the band gap energy of alkali halide.

  15. Coulomb explosion during the early stages of the reaction of alkali metals with water.

    PubMed

    Mason, Philip E; Uhlig, Frank; Vaněk, Václav; Buttersack, Tillmann; Bauerecker, Sigurd; Jungwirth, Pavel

    2015-03-01

    Alkali metals can react explosively with water and it is textbook knowledge that this vigorous behaviour results from heat release, steam formation and ignition of the hydrogen gas that is produced. Here we suggest that the initial process enabling the alkali metal explosion in water is, however, of a completely different nature. High-speed camera imaging of liquid drops of a sodium/potassium alloy in water reveals submillisecond formation of metal spikes that protrude from the surface of the drop. Molecular dynamics simulations demonstrate that on immersion in water there is an almost immediate release of electrons from the metal surface. The system thus quickly reaches the Rayleigh instability limit, which leads to a 'coulomb explosion' of the alkali metal drop. Consequently, a new metal surface in contact with water is formed, which explains why the reaction does not become self-quenched by its products, but can rather lead to explosive behaviour.

  16. Packing transition in alkali metallic clusters

    NASA Astrophysics Data System (ADS)

    Kawai, R.; Sung, Ming Wen; Weare, John H.

    1996-03-01

    Small metallic clusters form a local geometric configuration quite different from the bulk crystals. As the cluster size increases, several transitions in the local coordination take place before the bulk structure appears. These transitions involve change in the nature of chemical bonds. We have systematically investigated the structural transition of various alkali metal clusters including binary compounds using an ab initio molecular dynamics simulation. Among them, Li clusters exhibit unusual transition in their packing pattern. Small lithium clusters (N <= 21) form open structures based on a ``solvation shell''.(M. Sung, R. Kawai, and J. Weare, Phys. Rev. Lett. 73) (1994) 3552., which is quite different from other alkali metal clusters. The bonding of these small clusters is partially ionic. Above N=25, a close-packed structure is established. However, the local configuration still differ from that of the bulk crystal. As the size further increases, the ionic nature decreases and the system reaches another close-packed structure based on the Mackay icosahedron, which is similar to the bulk crystal structure.

  17. Cathode architectures for alkali metal / oxygen batteries

    SciTech Connect

    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.

  18. Electrodes For Alkali-Metal Thermoelectric Converters

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  19. Superconductivity in alkali metal intercalated iron selenides.

    PubMed

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  20. Superconductivity in alkali metal intercalated iron selenides.

    PubMed

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  1. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  2. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  3. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  4. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  5. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  6. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  7. Self-discharge in bimetallic cells containing alkali metal

    NASA Technical Reports Server (NTRS)

    Foster, M. S.; Hesson, J. C.; Shimotake, H.

    1969-01-01

    Theoretical analysis of thermally regenerative bimetallic cells with alkali metal anodes shows a relation between the current drawn and the rate of discharge under open-circuit conditions. The self-discharge rate of the cell is due to the dissolution and ionization of alkali metal atoms in the fused-salt electrolyte

  8. 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.

  9. 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.

  10. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  11. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  12. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  13. 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.

  14. 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.

  15. 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.

  16. (abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 < x < 6.0 ) with Na at Na-beta'-alumina, and Mo with K at K-beta'-alumina. Both liquid metal/solid electrolyte/alkali metal vapor and alkali metal vapor/solid electrolyte/vapor cells have been used to characterize the reaction and transport processes. We have previously reported evidence of ionic, free molecular flow, and surface transport of sodium in several types of AMTEC electrodes.

  17. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    PubMed

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  18. 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.

  19. 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.)

  20. The 4843 Alkali Metal Storage Facility Closure Plan

    SciTech Connect

    Not Available

    1991-06-01

    The 4843 AMSF has been used primarily to provide a centralized building to receive and store dangerous and mixed alkali metal waste, including sodium and lithium, which has been generated at the Fast Flux Test Facility and at various other Hanford Site operations that used alkali metals. Most of the dangerous and mixed alkali metal waste received consists of retired equipment from liquid sodium processes. The unit continues to store material. In general, only solid alkali metal waste that is water reactive is stored at the 4843 AMSF. The 4843 AMSF will be closed in a manner consistent with Ecology guidelines and regulations (WAC 173-303-610). The general closure procedure is detailed as follows.

  1. 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.

  2. Bioinorganic Chemistry of the Alkali Metal Ions.

    PubMed

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced. PMID:26860297

  3. Bioinorganic Chemistry of the Alkali Metal Ions.

    PubMed

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced.

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

    SciTech Connect

    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.

  5. 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.

  6. Assessment of alkali metal coolants for the ITER blanket

    SciTech Connect

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

    1994-06-01

    The blanket system is one of the most important components of a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The Blanket Comparison and Selection Study, conducted earlier, described the overall comparative performance of different blanket concepts, including liquid metal, molten salt, water and helium. This paper will discuss the ITER requirements for a self-cooled blanket concept with liquid lithium and for indirectly cooled concepts that use other alkali metals such as NaK. The paper addresses the thermodynamics of interactions between the liquid metals (e.g., lithium and NaK) and structural materials (e.g., V-base alloys), together with associated corrosion/compatibility issues. Available experimental data are used to assess the long-term performance of the first wall in a liquid metal environment. Other key issues include development of electrical insulator coatings on the first-wall structural material to MHD pressure drop, and tritium permeation/inventory in self-cooled and indirectly cooled concepts. Acceptable types of coatings (based on their chemical compatibility and physical properties) are identified, and surface-modification avenues to achieve these coatings on the first wall are discussed. The assessment examines the extent of our knowledge on structural materials performance in liquid metals and identifies needed research and development in several of the areas in order to establish performance envelopes for the first wall in a liquid-metal environment.

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

    SciTech Connect

    Antoniak, Z.I.

    1986-06-01

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

  8. 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; Cramer, Roger

    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 (AYO2) nanomaterials. The reaction of yttrium amide ([Y(NR2)3] where R=Si(CH3)3) with four equivalents of H-ONep followed by addition of [A(NR2)] (A=Li, Na, K) or Ao (Ao=Rb, Cs) led to the formation of a complex series of AnY(ONep)3+n species, crystallographically identified as [Y2Li3(μ3-ONep)(μ3-HONep)(μ-ONep)5(ONep)3(HONep)2] (1), [YNa2(μ3-ONep)4(ONep)]2 (2), {[Y2K3(μ3-ONep)3(μ-ONep)4(ONep)2(ηξ-tol)2][Y4K2(μ4-O)(μ3-ONep)8(ONep)4]•ηx-tol]} (3), [Y4K2(μ4-O)(μ3-ONep)8(ONep)4] (3a), [Y2Rb3(μ4-ONep)3(μ-ONep)6] (4), and [Y2Cs4(μ6-O)(μ3-ONep)6(μ3-HONep)2(ONep)2(ηx-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 weremore » found by powder X-ray diffraction experiments to be Y2O3 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

  9. 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.

  10. 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.

  11. Corrosion in alkali metal/molybdenum heat pipes

    SciTech Connect

    Lundberg, L.B.; Feber, R.C. Jr.

    1984-01-01

    Molybdenum/sodium (Mo/Na) and molybdenum/lithium (Mo/Li) heat pipes have been operated for long periods of time in a study of their resistance to failure by alkali metal corrosion. Some Mo/Na heat pipes have operated over 20,600 h at 1400 K without failure, while at least one similar heat pipe failed in less than 14 hours at 1435 K. Detailed post-mortem analyses which have been performed on three failed Mo/Na heat pipes all indicated impurity controlled corrosion of their evaporators. Impurities observed to be transported included carbon, oxygen, and silicon. A Mo/Li heat pipe that failed after 25,216 h of operation at 1700 K was also examined in detail. This failure was due to nickel impurities being transported to the evaporator resulting in perforation of the container tube by the formation of a low melting Mo-Ni alloy. Theoretical thermochemical calculations were conducted for these systems with the objective of corroborating the corrosion mechanisms in both types of heat pipes. The results of these calculations are in general agreement with the observed corrosion a phenomena.

  12. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts.

    PubMed

    Chen, Fangfang; Forsyth, Maria

    2016-07-28

    Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions. PMID:27375042

  13. Neuropsychiatric manifestations of alkali metal deficiency and excess.

    PubMed

    Yung, C Y

    1984-01-01

    The alkali metals from the Group IA of the periodic table (lithium, sodium, potassium, rubidium, cesium and francium) are reviewed. The neuropsychiatric aspects of alkali metal deficiencies and excesses (intoxications) are described. Emphasis was placed on lithium due to its clinical uses. The signs and symptoms of these conditions are characterized by features of an organic brain syndrome with delirium and encephalopathy prevailing. There are no clinically distinctive features that could be reliably used for diagnoses. Sodium and potassium are two essential alkali metals in man. Lithium is used as therapeutic agent in bipolar affective disorders. Rubidium has been investigated for its antidepressant effect in a group of psychiatric disorders. Cesium is under laboratory investigation for its role in carcinogenesis and in depressive illness. Very little is known of francium due to its great instability for experimental study. PMID:6395136

  14. C-CAMP, A closed cycle alkali metal power system

    SciTech Connect

    Wichner, R.P.; Hoffman, H.W.

    1988-01-01

    A concept is presented for a Closed-Cycle Alkali Metal (C-CAMP) power systems which utilizes the heat of reaction of an alkali metal and halogen compound to vaporize an alkali metal turbine fluid for a Rankine cycle. Unique features of the concept are (1) direct contact (heat exchange) between the reaction products and turbine fluid, and (2) a flow-through chemical reactor/boiler. The principal feasibility issues of the concept relate to the degree of cross-mixing of product and turbine fluid streams within the reactor-boiler. If proven feasible, the concept may be adapted to a range of fuel and turbine fluids and ultimately lead to thermal efficiencies in excess of 35%.

  15. Neuropsychiatric manifestations of alkali metal deficiency and excess

    SciTech Connect

    Yung, C.Y.

    1984-01-01

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

  16. 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.

  17. METHOD OF MAKING ALLOYS OF SECOND RARE EARTH SERIES METALS

    DOEpatents

    Baker, R.D.; Hayward, B.R.

    1963-01-01

    >This invention relates to a process for alloying the second rare earth series metals with Mo, Nb, or Zr. A halide of the rare earth metal is mixed with about 1 to 20 at.% of an oxide of Mo, Nb, or Zr. Iodine and an alkali or alkaline earth metal are added, and the resulting mixture is heated in an inert atmosphere to 350 deg C. (AEC)

  18. Transport properties of alkali metal doped fullerides

    SciTech Connect

    Yadav, Daluram Yadav, Nishchhal

    2015-07-31

    We have studied the intercage interactions between the adjacent C{sub 60} cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C{sub 60} phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, T{sub c}, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C{sub 60} phonons as 5 K, which is much lower as compared to reported T{sub c} (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity.

  19. Infrared Laser-Induced Breakdown Spectroscopy of Alkali Metal Halides

    NASA Astrophysics Data System (ADS)

    Brown, Ei; Hommerich, Uwe; Yang, Clayton; Trivedi, Sudhir; Samuels, Alan; Snyder, Peter

    2008-10-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful diagnostic tool for detection of trace elements by monitoring the atomic and ionic emission from laser-induced plasmas. LIBS is a relatively simple technique and has been successfully employed in applications such as environmental monitoring, materials analysis, medical diagnostics, industrial process control, and homeland security. Most LIBS applications are limited to emission features in the ultraviolet-visible-near infrared (UV-VIS-NIR) region arising from atoms and simple molecular fragments. In the present work, we report on the observation of mid- infrared emission lines from alkali metal halides due to laser-induced breakdown processes. The studied alkali metal halides included LiCl, NaCl, NaBr, KCl, KBr, KF, RbCl, and RbBr. The laser-induced plasma was produced by focusing a 16 mJ pulsed Nd:YAG laser (1064 nm) on the target. The LIBS infrared emission from alkali halides showed intense and narrow bands located in the region from 2-8 μm. The observed emission features were assigned to atomic transitions between higher-lying Rydberg states of neutral alkali atoms. More detailed results of the performed IR LIBS studies on alkali metal halides will be discussed at the conference.

  20. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  1. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong; Johnson, William L.

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

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

    PubMed

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

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. PMID:25984984

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

    PubMed

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

    2015-09-01

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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Alkali Metal Suboxometalates-Structural Chemistry between Salts and Metals.

    PubMed

    Wörsching, Matthias; Hoch, Constantin

    2015-07-20

    The crystal structures of the new cesium-poor alkali metal suboxometalates Cs10MO5 (M = Al, Ga, Fe) show both metallic and ionic bonding following the formal description (Cs(+))10(MO4(5-))(O(2-))·3e(-). Comparable to the cesium-rich suboxometalates Cs9MO4 (M = Al, Ga, In, Fe, Sc) with ionic subdivision (Cs(+))9(MO4(5-))·4e(-), they contain an oxometalate anion [M(III)O4](5-) embedded in a metallic matrix of cesium atoms. Columnlike building units form with prevalent ionic bonding inside and metallic bonding on the outer surface. In the cesium-rich suboxometalates Cs9MO4, additional cesium atoms with no contact to any anion are inserted between columns of the formal composition [Cs8MO4]. In the cesium-poor suboxometalates Cs10MO5, the same columns are extended by face-sharing [Cs6O] units, and no additional cesium atoms are present. The terms "cesium-rich" and "cesium-poor" here refer to the Cs:O ratio. The new suboxometalates Cs10MO5 crystallize in two modifications with new structure types. The orthorhombic modification adopts a structure with four formula units per unit cell in space group Pnnm with a = 11.158(3) Å, b = 23.693(15) Å, and c = 12.229(3) Å for Cs10AlO5. The monoclinic modification crystallizes with eight formula units per unit cell in space group C2/c with a = 21.195(3) Å, b = 12.480(1) Å, c = 24.120(4) Å, and β = 98.06(1)° for Cs10AlO5. Limits to phase formation are given by the restriction that the M atoms must be trivalent and by geometric size restrictions for the insertion of [Cs6O] blocks in Cs10MO5. All of the suboxometalate structures show similar structural details and form mixed crystal series with statistical occupation for the M elements following the patterns Cs9(M(1)xM(2)1-x)O4 and Cs10(M(1)xM(2)1-x)O5. The suboxometalates are a new example of ordered intergrowth of ionic and metallic structure elements, allowing for the combination of properties related to both ionic and metallic materials.

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  11. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

  12. 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...

  13. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

  14. 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...

  15. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  16. 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...

  17. 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...

  18. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

  19. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

  20. Valence bond cluster studies of alkali metal/semiconductor bonding

    NASA Astrophysics Data System (ADS)

    Tatar, Robert C.; Messmer, Richard P.

    1986-12-01

    We present results of cluster studies of alkali metal/semiconductor bonding. Using the Generalized Valence Bond (GVB) method, we find a remarkable consistency in the behavoir of bonding orbitals for a variety of systems, including: LiH, CLi4, LiH4 and several hypervalent systems, such as SiH3Li2, SiH4Li2. Our results show that the metal-semiconductor bonding in these systems can be understood in terms of a pairing between McAdon-Goddard type metallic bonding orbitals and a set of equivalent orbitals of the non-metallic species. We propose that the results are relevant to the initial stages of alkali overlayer growth on semiconductor surfaces and lead to a simple picture of the bonding including the transition from a non-conducting to a conducting layer. We have considered numerous proposed hypervalent structures in light of the above results and find that they can be understood.

  1. Core thresholds and charge-density waves in alkali metals

    NASA Astrophysics Data System (ADS)

    Bruhwiler, P. A.; Schnatterly, S. E.

    1988-07-01

    We have determined experimental upper limits on any broadening which could be due to a charge-density wave in Na and K metal soft x-ray-absorption and emisssion spectra. The upper limit for absorption in Na is a factor of 4 below the expected theoretical value. These results contradict expectations based on the present theory of charge-density waves in alkali metals.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  3. Subtask 12E1: Compatibility of structural materials in liquid alkali metals

    SciTech Connect

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

    1995-03-01

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures that are in the range of interest for the International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal environments. Candidate structural materials are being evaluated for their compatibility, interstitial-element transfer, and corrosion in liquid alkali-metal systems such as lithium and NaK. Type 316 stainless steel and V-5Cr-5Ti coupon specimens with and without prealuminizing treatment have been exposed to NaK and lithium environments of commercial purity for times up to 3768 h at temperatures between 300 and 400{degrees}C. 13 refs., 8 figs., 3 tabs.

  4. Mechanochemical processing for metals and metal alloys

    DOEpatents

    Froes, Francis H.; Eranezhuth, Baburaj G.; Prisbrey, Keith

    2001-01-01

    A set of processes for preparing metal powders, including metal alloy powders, by ambient temperature reduction of a reducible metal compound by a reactive metal or metal hydride through mechanochemical processing. The reduction process includes milling reactants to induce and complete the reduction reaction. The preferred reducing agents include magnesium and calcium hydride powders. A process of pre-milling magnesium as a reducing agent to increase the activity of the magnesium has been established as one part of the invention.

  5. Wetting Transitions of Inert Gases on Alkali Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Bojan, M. J.; McDonald, I. A.; Cole, M. W.; Steele, W. A.

    1996-03-01

    Theoretical and experimental discoveries have been made recently of wetting and prewetting transitions of helium and hydrogen films on alkali metal surfaces [1,2]. New experiments show anomalous nonwetting behavior of Ne on Rb and Cs [3]. Building on earlier work [4], we have done and will describe results from the first Monte Carlo simulations showing wetting transitions for classical gases on alkali metal surfaces. * Research supported by an NSF Materials Research Group grant. 1. R. B.Hallock, J. Low Temp. Phys. 101, 31, 1995 2. M. W. Cole, J. Low Temp. Phys. 101, 25, 1995. 3. G. B. Hess, M. Sabatini, and M. H. W. Chan, unpublished 4. J. E. Finn and P. A. Monson, Phys. Rev. A 39, 6402, 1989.

  6. High temperature corrosion behavior of commercial high temperature alloys under deposits of alkali salts

    SciTech Connect

    Kloewer, J.

    1995-12-31

    Corrosive deposits containing high amounts of alkali sulphates, chlorides and/or carbonates are encountered by heat exchanger tubes in a variety of industrial processes. Due to their low melting point the alkali salts can cause basic or acidic dissolution of the subjacent material, which results in rapid wastage of the tube. In order to select appropriate materials for application in heat recovery systems eight commercial high temperature materials (alloy 800H, Alloy 31, Alloy AC66, alloy 45-TM, Alloy 625, Alloy 59 and Alloy C-4) were investigated in sulphate, sulphate/chloride and sulphate/chloride/carbonate salt mixtures. The temperature range was between 550 and 750 C. In agreement with field tests the corrosion attack was high for most of the alloys tested with the corrosion rate depending sensitively on salt composition, test temperature and alloy composition. High molybdenum contents were found to be detrimental. Chromium did not effect the corrosion behavior significantly, whereas silicon had a beneficial effect on the corrosion resistance in molten alkali salts.

  7. 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.

  8. Calculation of the Lamb shift in neutral alkali metals

    NASA Astrophysics Data System (ADS)

    Sapirstein, J.; Cheng, K. T.

    2002-10-01

    The one-loop Lamb shift is calculated for the ground state of the neutral alkali metals lithium through francium. The method used is Furry representation QED, defined in terms of a variety of local potentials. The method is exact in binding corrections, but is potential dependent. Significant differences with known Lamb shift results for lithium are found, and it is shown that large corrections result from a partial set of screening corrections. Comparison with other calculations is made.

  9. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  10. Neutron imaging of alkali metal heat pipes

    SciTech Connect

    Kihm, Ken; Kirchoff, Eric; Golden, Matt; Rosenfeld, J.; Rawal, S.; Pratt, D.; Bilheux, Hassina Z; Walker, Lakeisha MH; Voisin, Sophie; Hussey, Dan

    2013-01-01

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

  11. The unexpected properties of alkali metal iron selenide superconductors

    SciTech Connect

    Dagotto, Elbio R

    2013-01-01

    The iron-based superconductors that contain FeAs layers as the fundamental building block in the crystal structures have been rationalized in the past using ideas based on the Fermi surface nesting of hole and electron pockets when in the presence of weak Hubbard U interactions. This approach seemed appropriate considering the small values of the magnetic moments in the parent compounds and the clear evidence based on photoemission experiments of the required electron and hole pockets. However, recent results in the context of alkali metal iron selenides, with generic chemical composition AxFe2ySe2 (A alkali metal element), have challenged those previous ideas since at particular compositions y the low-temperature ground states are insulating and display antiferromagnetic order with large iron magnetic moments. Moreover, angle-resolved photoemission studies have revealed the absence of hole pockets at the Fermi level in these materials. The present status of this exciting area of research, with the potential to alter conceptually our understanding of the ironbased superconductors, is here reviewed, covering both experimental and theoretical investigations. Other recent related developments are also briefly reviewed, such as the study of selenide two-leg ladders and the discovery of superconductivity in a single layer of FeSe. The conceptual issues considered established for the alkali metal iron selenides, as well as several issues that still require further work, are discussed.

  12. 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.

  13. Solvent effects and alkali metal ion catalysis in phosphodiester hydrolysis.

    PubMed

    Gomez-Tagle, Paola; Vargas-Zúñiga, Idania; Taran, Olga; Yatsimirsky, Anatoly K

    2006-12-22

    The kinetics of the alkaline hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) have been studied in aqueous DMSO, dioxane, and MeCN. In all solvent mixtures the reaction rate steadily decreases to half of its value in pure water in the range of 0-70 vol % of organic cosolvent and sharply increases in mixtures with lower water content. Correlations based on different scales of solvent empirical parameters failed to describe the solvent effect in this system, but it can be satisfactorily treated in terms of a simplified stepwise solvent-exchange model. Alkali metal ions catalyze the BNPP hydrolysis but do not affect the rate of hydrolysis of neutral phosphotriester p-nitrophenyl diphenyl phosphate in DMSO-rich mixtures. The catalytic activity decreases in the order Li+ > Na+ > K+ > Rb+ > Cs+. For all cations except Na+, the reaction rate is first-order in metal ion. With Na+, both first- and second-order kinetics in metal ions are observed. Binding constants of cations to the dianionic transition state of BNPP alkaline hydrolysis are of the same order of magnitude and show a similar trend as their binding constants to p-nitrophenyl phosphate dianion employed as a transition-state model. The appearance of alkali metal ion catalysis in a medium, which solvates metal ions stronger than water, is attributed to the increased affinity of cations to dianions, which undergo a strong destabilization in the presence of an aprotic dipolar cosolvent.

  14. Alkali metals conductivity at multistep dynamic compression

    NASA Astrophysics Data System (ADS)

    Postnov, Victor I.

    2005-07-01

    This work is devoted to studying of phase and structural transitions, in alkaline metals (lithium, sodium, potassium and calcium) at dynamic compression. Experiments were carried out at a room temperature and at temperature of liquid nitrogen with application of smooth shock wave technique. As a result for calcium almost tenfold increase in electrical resistance was observed at the maximal pressure 60GPa. Similar electrical resistance changing was fixed in sodium experiments. In experiments with lithium the range of pressure has been expanded up to 210GPa. The break on pressure-resistivity dependence at 160Gpa was found [1]. The fixed electrical resistance changing of samples at 120GPa makes about 70 times. Character of pressure-resistivity dependence for potassium samples qualitatively coincides with fixed for sodium and lithium. In unloading electrical resistance of all samples came back to the initial value. This phenomenon testified about convertibility of occurring processes. This work was supported by RFBR N03-02-16322, grant of the President of Russia N NS 1938.2003.2, program of basic researches of the Russian Academy of Science ``Thermophysics and mechanics of intensive energy influences'' and Russian Science Support Foundation. 1. V E Fortov, V V Yakushev, K l Kagan et al // J.Phys.: Condens Matter 14 (2002) 10809-10816

  15. Dirac Node Lines in Pure Alkali Earth Metals.

    PubMed

    Li, Ronghan; Ma, Hui; Cheng, Xiyue; Wang, Shoulong; Li, Dianzhong; Zhang, Zhengyu; Li, Yiyi; Chen, Xing-Qiu

    2016-08-26

    Beryllium is a simple alkali earth metal, but has been the target of intensive studies for decades because of its unusual electron behavior at surfaces. The puzzling aspects include (i) severe deviations from the description of the nearly free-electron picture, (ii) an anomalously large electron-phonon coupling effect, and (iii) giant Friedel oscillations. The underlying origins for such anomalous surface electron behavior have been under active debate, but with no consensus. Here, by means of first-principles calculations, we discover that this pure metal system, surprisingly, harbors the Dirac node line (DNL) that in turn helps to rationalize many of the existing puzzles. The DNL is featured by a closed line consisting of linear band crossings, and its induced topological surface band agrees well with previous photoemission spectroscopy observations on the Be (0001) surface. We further reveal that each of the elemental alkali earth metals of Mg, Ca, and Sr also harbors the DNL and speculate that the fascinating topological property of the DNL might naturally exist in other elemental metals as well. PMID:27610865

  16. Dirac Node Lines in Pure Alkali Earth Metals.

    PubMed

    Li, Ronghan; Ma, Hui; Cheng, Xiyue; Wang, Shoulong; Li, Dianzhong; Zhang, Zhengyu; Li, Yiyi; Chen, Xing-Qiu

    2016-08-26

    Beryllium is a simple alkali earth metal, but has been the target of intensive studies for decades because of its unusual electron behavior at surfaces. The puzzling aspects include (i) severe deviations from the description of the nearly free-electron picture, (ii) an anomalously large electron-phonon coupling effect, and (iii) giant Friedel oscillations. The underlying origins for such anomalous surface electron behavior have been under active debate, but with no consensus. Here, by means of first-principles calculations, we discover that this pure metal system, surprisingly, harbors the Dirac node line (DNL) that in turn helps to rationalize many of the existing puzzles. The DNL is featured by a closed line consisting of linear band crossings, and its induced topological surface band agrees well with previous photoemission spectroscopy observations on the Be (0001) surface. We further reveal that each of the elemental alkali earth metals of Mg, Ca, and Sr also harbors the DNL and speculate that the fascinating topological property of the DNL might naturally exist in other elemental metals as well.

  17. Dirac Node Lines in Pure Alkali Earth Metals

    NASA Astrophysics Data System (ADS)

    Li, Ronghan; Ma, Hui; Cheng, Xiyue; Wang, Shoulong; Li, Dianzhong; Zhang, Zhengyu; Li, Yiyi; Chen, Xing-Qiu

    2016-08-01

    Beryllium is a simple alkali earth metal, but has been the target of intensive studies for decades because of its unusual electron behavior at surfaces. The puzzling aspects include (i) severe deviations from the description of the nearly free-electron picture, (ii) an anomalously large electron-phonon coupling effect, and (iii) giant Friedel oscillations. The underlying origins for such anomalous surface electron behavior have been under active debate, but with no consensus. Here, by means of first-principles calculations, we discover that this pure metal system, surprisingly, harbors the Dirac node line (DNL) that in turn helps to rationalize many of the existing puzzles. The DNL is featured by a closed line consisting of linear band crossings, and its induced topological surface band agrees well with previous photoemission spectroscopy observations on the Be (0001) surface. We further reveal that each of the elemental alkali earth metals of Mg, Ca, and Sr also harbors the DNL and speculate that the fascinating topological property of the DNL might naturally exist in other elemental metals as well.

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

    PubMed

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

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

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 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...

  20. 40 CFR 721.10098 - Disubstituted benzoic acid, alkali metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 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...

  1. 40 CFR 721.10097 - Disubstituted benzenesulfonic acid, alkali metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., 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...

  2. 40 CFR 721.10097 - Disubstituted benzenesulfonic acid, alkali metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., 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...

  3. 40 CFR 721.10098 - Disubstituted benzoic acid, alkali metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 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...

  4. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 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...

  5. 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...

  6. 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...

  7. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 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...

  8. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 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...

  9. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 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...

  10. 40 CFR 721.10097 - Disubstituted benzenesulfonic acid, alkali metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., 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...

  11. 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...

  12. 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...

  13. 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...

  14. Substitution mechanism of alkali metals for strontium in strontium hydroxyapatite

    SciTech Connect

    Naddari, Thouraya; Hamdi, Besma; Savariault, Jean Michel; El Feki, Hafed; Ben Salah, Abdelhamid

    2003-01-25

    Strontium hydroxyapatites substituted by alkali metals are synthesized by double decomposition method in basic medium. Structures of Sr{sub 9.50}Na{sub 0.30}(PO{sub 4}){sub 6}(OH){sub 1.30} (SrNaHAp) and Sr{sub 9.81}K{sub 0.12}(PO{sub 4}){sub 6}(OH){sub 1.74} (SrKHAp) are determined by X-ray powder diffraction. Both compounds are isotypic and crystallize in hexagonal system (space group P63/m) with the following cells: a=9.751(3) A and c=7.279(3) A for SrNaHAp and a=9.755(4) A and c=7.284(3) A for SrKHAp. Results are compared to those of Sr{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}. According to the site occupancy factors, in SrNaHAp sodium is localized in site (I) and in SrKHAp potassium in site (II). Both structures contain vacancies in hydroxyl and metal sites. The mechanism of alkali metals substitution for strontium proposed explains the vacancies formation.

  15. An Alkali Metal-Capped Cerium(IV) Imido Complex.

    PubMed

    Solola, Lukman A; Zabula, Alexander V; Dorfner, Walter L; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

    2016-06-01

    Structurally authenticated, terminal lanthanide-ligand multiple bonds are rare and expected to be highly reactive. Even capped with an alkali metal cation, poor orbital energy matching and overlap of metal and ligand valence orbitals should result in strong charge polarization within such bonds. We expand on a new strategy for isolating terminal lanthanide-ligand multiple bonds using cerium(IV) complexes. In the current case, our tailored tris(hydroxylaminato) ligand framework, TriNOx(3-), provides steric protection against ligand scrambling and metal complex oligomerization and electronic protection against reduction. This strategy culminates in isolation of the first formal Ce═N bonded moiety in the complex [K(DME)2][Ce═N(3,5-(CF3)2C6H3)(TriNOx)], whose Ce═N bond is the shortest known at 2.119(3) Å. PMID:27163651

  16. 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.

  17. 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.

  18. Nuclear alkali metal Rankine power systems for space applications

    SciTech Connect

    Moyers, J.C.; Holcomb, R.S.

    1986-08-01

    Nucler power systems utilizing alkali metal Rankine power conversion cycles offer the potential for high efficiency, lightweight space power plants. Conceptual design studies are being carried out for both direct and indirect cycle systems for steady state space power applications. A computational model has been developed for calculating the performance, size, and weight of these systems over a wide range of design parameters. The model is described briefly and results from parametric design studies, with descriptions of typical point designs, are presented in this paper.

  19. 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.

  20. On strain energy and constitutive relations for alkali metals.

    NASA Technical Reports Server (NTRS)

    Eftis, J.; Arkilic, G. M.; Macdonald, D. E.

    1971-01-01

    An expression for the strain energy as a continuous differentiable function of the Green-Cauchy deformation tensor is obtained for the alkali metals at absolute zero temperature. The development is based on well established quantum and classical calculations of the various contributions to the crystal energy. Stress-deformation relations are next obtained. As a check on the accuracy of the strain energy, theoretical calculations of the values of the second-order elastic coefficients are obtained and compared to known experimental data. The predicted values are shown to compare quite well with the experimental values.

  1. Theoretical determination of the alkali-metal superoxide bond energies

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Bauschlicher, Charles W., Jr.; Sodupe, Mariona; Langhoff, Stephen R.

    1992-01-01

    The bond dissociation energies for the alkali-metal superoxides have been computed using extensive Gaussian basis sets and treating electron correlation at the modified coupled-pair functional level. Our computed D0 values are 61.4, 37.2, 40.6, and 38.4 kcal/mol for LiO2, NaO2, KO2, and RbO2, respectively. These values, which are expected to be lower bounds and accurate to 2 kcal/mol, agree well with some of the older flame data, but rule out several recent experimental measurements.

  2. Optical response of alkali metal atoms confined in nanoporous glass

    SciTech Connect

    Burchianti, A; Marinelli, C; Mariotti, E; Bogi, A; Marmugi, L; Giomi, S; Maccari, M; Veronesi, S; Moi, L

    2014-03-28

    We study the influence of optical radiation on adsorption and desorption processes of alkali metal atoms confined in nanoporous glass matrices. Exposure of the sample to near-IR or visible light changes the atomic distribution inside the glass nanopores, forcing the entire system to evolve towards a different state. This effect, due to both atomic photodesorption and confinement, causes the growth and evaporation of metastable nanoparticles. It is shown that, by a proper choice of light characteristics and pore size, these processes can be controlled and tailored, thus opening new perspectives for fabrication of nanostructured surfaces. (nanoobjects)

  3. Burner rig alkali salt corrosion of several high temperature alloys

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Lowell, C. E.

    1977-01-01

    The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

  4. Work function of alkali metal-adsorbed molybdenium dichalcogenides

    NASA Astrophysics Data System (ADS)

    Kim, Sol; Jhi, Seung-Hoon

    2015-03-01

    The lowest work function of materials, reported so far over the last few decades, is an order of 1eV experimentally and theoretically. Designing materials that has work-function less than 1eV is essential in the thermionic energy conversion. To explore new low work function materials, we study MoX2(X =S, Se, Te) adsorbed with alkali metals (Li, Na, K, Rb and Cs), and investigate the charge transfer, the formation of surface dipole, and the change in work function using first-principles calculations. It is found that the charge transfer from alkali metals to MoX2substrates decreases as the atomic number of adsorbates increases. Regardless of the amount of the charge transfer, K on MoTe2 exhibits the biggest surface dipole moment, which consequently makes the surface work function the lowest. We show that the formation of the surface dipole is a key in changing the work function. We find the trimerization of Mo atoms in the substrate with the lowest work-function, which may contribute to enhancement of the surface dipole.

  5. Band gap opening in bilayer silicene by alkali metal intercalation.

    PubMed

    Liu, Hongsheng; Han, Nannan; Zhao, Jijun

    2014-11-26

    Recently, bilayer and multilayer silicene have attracted increased attention following the boom of silicene, which holds great promise for future applications in microelectronic devices. Herein we systematically investigate all stacking configurations of bilayer silicene and the corresponding electronic properties. Strong coupling is found between two silicene layers, which destroys the Dirac cones in the band structures of pristine silicene and makes bilayer silicene sheets metallic. However, intercalation of alkali metal (especially potassium) can effectively decouple the interaction between two silicene layers. In the K-intercalated bilayer silicene (KSi4), the Dirac cones are recovered with a small band gap of 0.27 eV located about 0.55 eV below the Fermi level. Furthermore, intercalation of K(+) cations in bilayer silicene (K(+)Si4) results in a semiconductor with a moderate band gap of 0.43 eV, making it ideal for microelectronic applications.

  6. Electronic properties of metal-induced gap states formed at alkali-halide/metal interfaces

    NASA Astrophysics Data System (ADS)

    Kiguchi, Manabu; Yoshikawa, Genki; Ikeda, Susumu; Saiki, Koichiro

    2005-04-01

    The spatial distribution and site distribution of metal-induced gap states (MIGS) are studied by thickness-dependent near-edge x-ray absorption fine structure (NEXAFS) and by comparing the cation and anion-edge NEXAFS. The thickness-dependent NEXAFS shows that the decay length of MIGS depends on an alkali-halide rather than a metal, and it is larger for alkali-halides with smaller band gap energies. By comparing the Cl-edge and K-edge NEXAFS for KCl/Cu (001) , MIGS are found to be states localizing at anion sites.

  7. Difficulties in Interpreting Alkali Metal Trends at the Senior Chemistry Level.

    ERIC Educational Resources Information Center

    de Berg, Kevin

    2001-01-01

    Explores the reasons for the differences in alkali metal reactivity in water in terms of thermodynamics rather than ionization trends. Shows that differences in alkali metal reactivity with water are more appropriately explained in terms of the kinetics of the reactions. (MM)

  8. Supported metal alloy catalysts

    DOEpatents

    Barrera, Joseph; Smith, David C.

    2000-01-01

    A process of preparing a Group IV, V, or VI metal carbonitride including reacting a Group IV, V, or VI metal amide complex with ammonia to obtain an intermediate product; and, heating the intermediate product to temperatures and for times sufficient to form a Group IV, V, or VI metal carbonitride is provided together with the product of the process and a process of reforming an n-alkane by use of the product.

  9. Ion-exchange behavior of alkali metals on treated carbons

    SciTech Connect

    Mohiuddin, G.; Hata, W.Y.; Tolan, J.S.

    1983-01-01

    The ion-exchange behavior of trace quantities of the alkali-metal ions sodium and cesium, on activated carbon impregnated with zirconium phosphate (referred to here as ZrP), was studied. Impregnated carbon had twice as much ion-exchange activity as unimpregnated, oxidized carbon, and 10 times as much as commercial activated carbons. The distribution coefficient of sodium increased with increasing pH; the distribution coefficient of cesium decreased with increasing pH. Sodium and cesium were separated with an electrolytic solution of 0.1 M HCl. Preliminary studies indicated that 0.2 M potassium and cesium can also be separated. Distribution coefficients of the supported ZrP were determined by the elution technique and agreed within 20% of the values for pure ZrP calculated from the literature.

  10. Mechanical stiffening and thermal softening of superionic alkali metal oxides

    NASA Astrophysics Data System (ADS)

    Chaudhary, S.; Shriya, S.; Kumar, J.; Ameri, M.; Varshney, Dinesh

    2015-06-01

    The mechanical (pressure) and thermal (temperature) dependent nature of superionic cubic M2O (M = Li, Na, K, and Rb) alkali metal oxides is studied. The model Hamiltonian in ab initio theory include long-range Coulomb, charge transfer, covalency, van der Waals interaction and the short-range repulsive interaction upto second-neighbor ions. The second order elastic constants as functions of pressure discern increasing trend, while to that they decreases with enhanced temperature. From the knowledge of elastic constants, Pugh ratio, Poisson's ratio, heat capacity and thermal expansion coefficient are calculated. It is noticed that cubic M2O is brittle on applied pressure and temperature and mechanically stiffened as a consequence of bond compression and bond strengthening and thermally softened due to bond expansion and bond weakening due to lattice vibrations.

  11. Alkali Metal Thermoelectric Conversion (AMTEC) for space nuclear power systems

    NASA Astrophysics Data System (ADS)

    Bankston, C. P.; Cole, T.; Khanna, S. K.; Thakoor, A. P.

    Performance parameters of the Alkali Metal Thermoelectric Converter (AMTEC) for a 100 kW electric power system have been calculated at four technological levels assuming a heat pipe-cooled nuclear reactor heat source. The most advanced level considered would operate between 1180 K converter temperature and 711 K radiator temperature at 16 percent efficiency, and would weigh 1850 kg with a radiator area of 43 sq m. In addition, electrode research studies for the AMTEC systems have been conducted utilizing an experimental test cell of Bankston et al. (1983) and Mo and several Mo-Ti electrodes. It was found that the Mo-Ti electrodes offered no improvement in lifetime characteristics over the pure Mo electrodes, however, oxygen treatment of a degraded Mo electrode restored its specific power output to 90 percent of its original specific power and maintained this level for 60 hr, thus offering a potential for lifetime stability.

  12. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    SciTech Connect

    1991-12-01

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

  13. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  14. Ultraprecision microelectroforming of metals and metal alloys

    NASA Astrophysics Data System (ADS)

    Loewe, Holger; Ehrfeld, Wolfgang; Diebel, Joerg

    1997-09-01

    In recent years, microsystem technology and its growing importance for actuators, sensors, optics and microfluidics, only to name a few, have gained a lot of attention. Specific applications demand fabrication techniques allowing a fast and reliable replication of microstructure products in a variety of materials. An important technique for replication processes of microstructures in many applications of microsystem technology are microelectroforming processes, generating a variety of metals and metal alloys with tailored characteristics. Here, new results in the development of alloys for specific applications as well as their applications are reported: (1) Newly developed alloys: Nickel-iron alloys enable the production of soft magnetic microstructures e.g. for specific applications in microactuators. Nickel-cobalt and Nickel-tungsten alloys have been employed for the manufacture of microstructured tools with excellent mechanical properties regarding wear and mechanical durability. These tools have been applied to hot-embossing and injection molding processes successfully. (2) Microelectroforming within the frame of the LIGA technique allows the manufacturing of extremely precise electrodes with various cross-sections and heights for (mu) - electro discharge machining. The combination of these techniques enables the production of microstructures from non- electrodepositable materials, like stainless steel e.g. for large scale replication processes. (3) The precision of microelectroforming enables the replication of structured surfaces on a nanoscale for molecular microelectronics or special applications. The new types of alloys reported here significantly enlarge the applicability of microelectroforming processes for tool fabrication or direct use. Moreover combining this process with other microstructuring processes like injection molding or (mu) -EDM techniques generates a powerful tool for microsystem technology.

  15. Alkali-Metal Atoms as Spin Labels on Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Koch, Markus; Ratschek, Martin; Callegari, Carlo; Ernst, Wolfgang E.

    2010-06-01

    We have recently achieved electron spin resonance (ESR) of single alkali-metal atoms isolated on helium (He) nanodroplets A two-laser pump/probe setup for optically detected magnetic resonance is applied, which is based on magnetic circular dichroism to selectively address spin states. The influence of the helium droplet on the alkali-metal valence-electron wave function is directly noticeable as a shift of the ESR transitions with respect to that of free atoms. This perturbation depends on the size of the droplets and can be modeled with an increase of the hyperfine constant, that is an increase of the Fermi contact interaction. After careful characterization of the Rb--He-droplet system the method is being developed into a more universal diagnostic tool to study spin dynamics. ESR silent species located inside the droplet can be investigated by utilizing the surface Rb atom as spin label, and the droplet size is a convenient handle to control the distance between the two. In case of species with a nuclear spin (e.g., 129Xe) spin exchange between the optically pumped Rb atom and the nuclear spin can be studied. We are also extending our method to study magnetically active materials of technological importance, such as Cr, Cu, and small clusters thereof, and we strive to present the first results at the meeting. M. Koch, G. Auböck, C. Callegari, and W.E. Ernst, Phys. Rev. Lett. 103, 035302 (2009) M. Koch, J. Lanzersdorfer, C. Callegari, J.S. Muenter, and W.E. Ernst, J. Phys. Chem. A 113, 13347 (2009) M. Koch, C. Callegari, and W.E. Ernst, Mol. Phys., in press.

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

    PubMed

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

    2012-07-01

    Investigating the release characteristics of alkali and alkaline earth metallic species (AAEMs) is of potential interest because of AAEM's possible useful service as catalysts in biomass thermal conversion. In this study, three kinds of typical Chinese biomass were selected to pyrolyse and their chars were subsequently steam gasified in a designed quartz fixed-bed reactor to investigate the release characteristics of alkali and alkaline earth metallic species (AAEMs). The results indicate that 53-76% of alkali metal and 27-40% of alkaline earth metal release in pyrolysis process, as well as 12-34% of alkali metal and 12-16% of alkaline earth metal evaporate in char gasification process, and temperature is not the only factor to impact AAEMs emission. The releasing characteristics of AAEMs during pyrolysis and char gasification process of three kinds of biomass were discussed in this paper. PMID:22525260

  17. 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.

  18. Self-disintegrating Raney metal alloys

    DOEpatents

    Oden, Laurance L.; Russell, James H.

    1979-01-01

    A method of preparing a Raney metal alloy which is capable of self-disintegrating when contacted with water vapor. The self-disintegrating property is imparted to the alloy by incorporating into the alloy from 0.4 to 0.8 weight percent carbon. The alloy is useful in forming powder which can be converted to a Raney metal catalyst with increased surface area and catalytic activity.

  19. Calculation of radiative corrections to E1 matrix elements in the neutral alkali metals

    SciTech Connect

    Sapirstein, J.; Cheng, K.T.

    2005-02-01

    Radiative corrections to E1 matrix elements for ns-np transitions in the alkali-metal atoms lithium through francium are evaluated. They are found to be small for the lighter alkali metals but significantly larger for the heavier alkali metals, and in the case of cesium much larger than the experimental accuracy. The relation of the matrix element calculation to a recent decay rate calculation for hydrogenic ions is discussed, and application of the method to parity nonconservation in cesium is described.

  20. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  1. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Peyghan, Ali Ahmadi; Noei, Maziar

    2014-01-01

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

  4. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M.; Utlaut, Mark W.; Behrens, Robert G.; Szklarz, Eugene G.; Storms, Edmund K.; Santandrea, Robert P.; Swanson, Lynwood W.

    1988-10-04

    A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

  5. In vitro bioactivity investigation of alkali treated Ti6Al7Nb alloy foams

    NASA Astrophysics Data System (ADS)

    Butev, Ezgi; Esen, Ziya; Bor, Sakir

    2015-02-01

    Biocompatible Ti6Al7Nb alloy foams with 70% porosity manufactured by space holder method were activated via alkali treatment using 5 M NaOH solution at 60 °C. The interconnected pore structures enabled formation of homogenous sodium rich coating on the foam surfaces by allowing penetration of alkali solution throughout the pores which had average size of 200 μm. The resulted coating layer having 500 nm thickness exhibited porous network morphology with 100 nm pore size. On the other hand, heat treatment conducted subsequent to alkali treatment at 600 °C in air transformed sodium rich coating into crystalline bioactive sodium titanate phases. Although the coatings obtained by additional heat treatment were mechanically stable and preserved their morphology, oxidation of the samples deteriorated the compressive strength significantly without affecting the elastic modulus. However, heat treated samples revealed better hydroxyapatite formation when soaked in simulated body fluid (SBF) compared to alkali treated foams. On the other hand, untreated surfaces containing bioactive TiO2 layer were observed to comprise of Ca and P rich precipitates only rather than hydroxyapatite within 15 days. The apatite formed on the treated porous surfaces was observed to have flower-like structure with Ca/P ratio around 1.5 close to that of natural bone.

  6. 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). PMID:21928287

  7. Modification of alkali metals on silicon-based nanoclusters: An enhanced nonlinear optical response

    NASA Astrophysics Data System (ADS)

    Li, Xiaojun; Han, Quan; Yang, Xiaohui; Song, Ruijuan; Song, Limei

    2016-08-01

    Structures, chemical stabilities and nonlinear optical properties of alkali metals-adsorbed niobium-doped silicon (M@SinNb+) clusters are investigated using the DFT methods. The alkali metals prefer energetically to be attached as bridged bond rather than M-Si single bond in most of optimized structures. Adsorption of alkali metals on doped silicon clusters gradually enhances their chemical stabilities with increasing cluster size. Noteworthily, the first hyperpolarizabilities (βtot) of the M@SinNb+ clusters, obtained by using the long-range corrected CAM-B3LYP functional, are large enough to establish their strong nonlinear optical behavior, especially for M@Si9Nb+ (M = Li, Na, and K), and the enhanced βtot ordering by alkali metals is Na > K > Li.

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

    SciTech Connect

    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, 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 polyatomic nature of NH4.

  9. 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.

  10. 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.

  11. 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.

  12. Design of low work function materials using alkali metal-doped transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Kim, Sol; Lee, Man Young; Lee, Seong; Jhi, Seung-Hoon

    Engineering the work function is a key issue in surface science. Particularly, discovering the materials that have work functions less than 1eV is essential for efficient thermionic energy conversion. The lowest work function of materials, reported so far, is in a range of about 1eV. To design low work function materials, we chose MX2 (M =Mo and W; X =S, Se and Te) as substrates and alkali metals (Li, Na, K, Rb and Cs) as dopants, and studied their electronic structures, charge transfer, induced surface dipole moment, and work function using first-principles calculations. We found that the charge transfer from alkali metals to MX2 substrates decreases as the atomic radius of alkali metals increases. Regardless of the amount of the charge transfer, K on WTe2 exhibits the biggest surface dipole moment, which consequently makes the surface work function the lowest. Also, we found a correlation between the binding distance and the work function.

  13. 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.

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

    PubMed

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

    2016-03-21

    Alkali metal cations can interact with Fe-N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber-Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding their influence on transition metal-dinitrogen complexes. In this work, we varied the alkali metal in [alkali cation]2[LFeNNFeL] complexes (L = bulky β-diketiminate ligand) through the size range from Na(+) to K(+), Rb(+), and Cs(+). The FeNNFe cores have similar Fe-N and N-N distances and N-N stretching frequencies despite the drastic change in alkali metal cation size. The two diketiminates twist relative to one another, with larger dihedral angles accommodating the larger cations. In order to explain why the twisting has so little influence on the core, we performed density functional theory calculations on a simplified LFeNNFeL model, which show that the two metals surprisingly do not compete for back-bonding to the same π* orbital of N2, even when the ligand planes are parallel. This diiron system can tolerate distortion of the ligand planes through compensating orbital energy changes, and thus, a range of ligand orientations can give very similar energies. PMID:26925968

  15. 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.

  16. Metal dusting of nickel-containing alloys

    SciTech Connect

    Baker, B.A.; Smith, G.D.

    1998-12-31

    Metal dusting is a catastrophic form of carburization which leads to pitting and grooves as the affected metal disintegrates into a mixture of powdery carbon, metallic particles, and possibly oxides and carbides. This high temperature carburization mode is not yet well understood and while relatively infrequent, can be economically disastrous when it does occur in large and complex chemical and petrochemical process streams. References in the literature show that all classes of heat resistant alloys are prone to metal dusting, given the necessary and specific environmental conditions. These same references describe the environments that plague nickel-containing alloys and are used as the basis for postulation on the probable corrosion mechanisms responsible for metal dusting. Using alloy 800 and other nickel-containing alloys and metal dusting atmospheres, an effort is made to examine the steps in the metal dusting process and the temperature ranges over which metal dusting occurs.

  17. Half metallic ferromagnetism in alkali metal nitrides MN (M = Rb, Cs): A first principles study

    SciTech Connect

    Murugan, A. Rajeswarapalanichamy, R. Santhosh, M. Sudhapriyanga, G.; Kanagaprabha, S.

    2014-04-24

    The structural, electronic and elastic properties of two alkali metal nitrides (MN: M= Rb, Cs) are investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At ambient pressure the two nitrides are stable in ferromagnetic state with CsCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic in nature. A pressure-induced structural phase transition from CsCl to ZB phase is observed in RbN and CsN.

  18. Note: An ion source for alkali metal implantation beneath graphene and hexagonal boron nitride monolayers on transition metals

    SciTech Connect

    Lima, L. H. de; Cun, H. Y.; Hemmi, A.; Kälin, T.; Greber, T.

    2013-12-15

    The construction of an alkali-metal ion source is presented. It allows the acceleration of rubidium ions to an energy that enables the penetration through monolayers of graphene and hexagonal boron nitride. Rb atoms are sublimated from an alkali-metal dispenser. The ionization is obtained by surface ionization and desorption from a hot high work function surface. The ion current is easily controlled by the temperature of ionizer. Scanning Tunneling Microscopy measurements confirm ion implantation.

  19. Improving the bioactivity of NiTi shape memory alloy by heat and alkali treatment

    NASA Astrophysics Data System (ADS)

    Qiang, Wei; Zhen-duo, Cui; Xian-jin, Yang; Jie, Shi

    2008-11-01

    TiO 2 films were formed on an NiTi alloy surface by heat treatment in air at 600 °C. Heat treated NiTi shape memory alloys were subsequently alkali treated with 1 M, 3 M and 5 M NaOH solutions respectively, to improve their bioactivity. Then treated NiTi samples were soaked in 1.5SBF to evaluate their in vitro performance. The results showed that the 3 M NaOH treatment is the most appropriate method. A large amount of apatite formed within 1 day's soaking in 1.5SBF, after 7 day's soaking TiO 2/HA composite layer formed on the NiTi surface. SEM, XRD, FT-IR and TEM results showed that the morphology and microstructure are similar to the human bone apatite.

  20. 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.

  1. 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.

  2. Multi-photon processes in alkali metal vapors

    NASA Astrophysics Data System (ADS)

    Gai, Baodong; Hu, Shu; Li, Hui; Shi, Zhe; Cai, Xianglong; Guo, Jingwei; Tan, Yannan; Liu, Wanfa; Jin, Yuqi; Sang, Fengting

    2015-02-01

    Achieving population inversion through multi-photon cascade pumping is almost always difficult, and most laser medium work under 1-photon excitation mechanism. But for alkali atoms such as cesium, relatively large absorption cross sections of several low, cascading energy levels enable them properties such as up conversion. Here we carried out research on two-photon excitation alkali fluorescence. Two photons of near infrared region are used to excite alkali atoms to n 2 D5/2, n 2 D3/2 or higher energy levels, then the blue fluorescence of (n+1) 2 P3/2,(n+1) 2 P1/2-->n 2 S1/2 are observed. Different pumping paths are tried and by the recorded spectra, transition routes of cesium are deducted and concluded. Finally the possibility of two-photon style DPALs (diode pumped alkali laser) are discussed, such alkali lasers can give output wavelengths in the shorter end of visual spectroscopy (400-460 nm) and are expected to get application in underwater communication and material laser processing.

  3. Development of Metallic Sensory Alloys

    NASA Technical Reports Server (NTRS)

    Wallace Terryl A.; Newman, John A.; Horne, Michael R.; Messick, Peter L.

    2010-01-01

    Existing nondestructive evaluation (NDE) technologies are inherently limited by the physical response of the structural material being inspected and are therefore not generally effective at the identification of small discontinuities, making the detection of incipient damage extremely difficult. One innovative solution to this problem is to enhance or complement the NDE signature of structural materials to dramatically improve the ability of existing NDE tools to detect damage. To address this need, a multifunctional metallic material has been developed that can be used in structural applications. The material is processed to contain second phase sensory particles that significantly improve the NDE response, enhancing the ability of conventional NDE techniques to detect incipient damage both during and after flight. Ferromagnetic shape-memory alloys (FSMAs) are an ideal material for these sensory particles as they undergo a uniform and repeatable change in both magnetic properties and crystallographic structure (martensitic transformation) when subjected to strain and/or temperature changes which can be detected using conventional NDE techniques. In this study, the use of a ferromagnetic shape memory alloy (FSMA) as the sensory particles was investigated.

  4. 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. PMID:25317749

  5. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  8. Dissolution Process of Palladium in Hydrochloric Acid: A Route via Alkali Metal Palladates

    NASA Astrophysics Data System (ADS)

    Kasuya, Ryo; Miki, Takeshi; Morikawa, Hisashi; Tai, Yutaka

    2015-12-01

    To improve the safety of the Pd recovery processes that use toxic oxidizers, dissolution of Pd in hydrochloric acid with alkali metal palladates was investigated. Alkali metal palladates were prepared by calcining a mixture of Pd black and alkali metal (Li, Na, and K) carbonates in air. Almost the entire amount of Pd was converted into Li2PdO2 after calcination at 1073 K (800 °C) using Li2CO3. In contrast, PdO was obtained by calcination at 1073 K (800 °C) using Na and K carbonates. Our results indicated that Li2CO3 is the most active reagent among the examined alkali metal carbonates for the formation of palladates. In addition, dissolution of the resulting Li2PdO2 in HCl solutions was evaluated under various conditions. In particular, Li2PdO2 rapidly dissolved in diluted (0.1 M) HCl at ambient temperature. Solubility of Pd of Li2PdO2 was found to be 99 pct or larger after dissolution treatment at 353 K (80 °C) for 5 minutes; in contrast, PdO hardly dissolved in 0.1 M HCl. The dissolution mechanism of Li2PdO2 in HCl was also elucidated by analysis of crystal structures and particulate properties. Since our process is completely free from toxic oxidizers, the dissolution process via alkali metal palladates is much safer than currently employed methods.

  9. [Biocompatibility of precious metal dental alloys].

    PubMed

    Reuling, N; Pohl-Reuling, B; Keil, M

    1991-03-01

    The local toxicity of three dental gold alloys was examined by help of intramuscular implantation tests in rabbits. For each alloy implantation periods of 1, 2, 4, 8, and 12 weeks were used. The local tissue reactions (foreign body reactions) were judged and graded by use of quantitative histomorphometry. Furthermore specific cellular parameters were examined with semiquantitative histopathologic methods to get an toxicity index for each material. The local tissue reactions caused by the implanted dental alloys were judged in relation to those, caused by biological inert materials (titanium, aluminum-oxide-ceramics) respectively materials with well-known toxic potential (polyvinyl-chloride with toxic aids), after intramuscular implantation in the same animals. Significant differences were found in the tissue reactions caused by the dental gold alloys; an gold alloy with lower noble metal content elicited stronger tissue reactions than both gold alloys with high noble metal content did. PMID:1872036

  10. Evaluation of alkali metal sulfate dew point measurement for detection of hot corrosion conditions in PFBC flue gas

    SciTech Connect

    Helt, J.E.

    1980-11-01

    Hot corrosion in combustion systems is, in general, the accelerated oxidation of nickel, cobalt, and iron-base alloys which occurs in the presence of small amounts of impurities - notably, sodium, sulfur, chlorine, and vanadium. There is no real consensus on which mechanisms are primarily responsible for high-temperature corrosion. One point generally accepted, however, is that corrosion reactions take place at an appreciable rate only in the presence of a liquid phase. When coal is the fuel for combustion, hot corrosion may occur in the form of accelerated sulfidation. It is generally agreed by investigators that molten alkali metal sulfates (Na/sub 2/SO/sub 4/ and K/sub 2/SO/sub 4/) are the principal agents responsible for the occurrence of sulfidation. Although molten sodium sulfate by itself appears to have little or no effect on the corrosion of metal alloys, its presence may increase the accessibility of the bare metal surface to the external atmosphere. If this atmosphere contains either a reductant and/or an oxide such as SiO/sub 2/, SO/sub 3/, or NaOH(Na/sub 2/O), corrosion is likely to occur. Alkali metal sulfate dew point measurement was evaluated as a means of anticipating hot corrosion in the gas turbine of a pressurized fluidized-bed combustion system. The hot corrosion mechanism and deposition rate theory were reviewed. Two methods of dew point measurement, electrical conductivity and remote optical techniques, were identified as having a potential for this application. Both techniques are outlined; practical measurement systems are suggested; and potential problem areas are identified.

  11. Dissociation of alkaliated alanine in the gas phase: the role of the metal cation.

    PubMed

    Abirami, Seduraman; Wong, Catherine Chiu Lan; Tsang, Chun Wai; Ma, Ngai Ling

    2005-09-01

    The dissociation of prototypical metal-cationized amino acid complexes, namely, alkaliated alanine ([Ala+M]+, M+ = Li+, Na+, K+), was studied by energy-resolved tandem mass spectrometry with an ion-trap mass analyzer and by density functional theory. Dissociation leads to formation of fragment ions arising from the loss of small neutrals, such as H2O, CO, NH3, (CO+NH3), and the formation of Na+/K+. The order of appearance threshold voltages for different dissociation pathways determined experimentally is consistent with the order of critical energies (energy barriers) obtained theoretically, and this provides the necessary confidence in both experimental and theoretical results. Although not explicitly involved in the reaction, the alkali metal cation plays novel and important roles in the dissociation of alkaliated alanine. The metal cation not only catalyzes the dissociation (via the formation of loosely bound ion-molecule complexes and by stabilizing the more polar intermediates and transition structures), but also affects the dissociation mechanisms, as the cation can alter the shape of the potential energy surfaces. This compression/expansion of the potential energy surface as a function of the alkali metal cation is discussed in detail, and how this affects the competitive loss of H2O versus CO/(CO+NH3) from [Ala+M]+ is illustrated. The present study provides new insights into the origin of the competition between various dissociation channels of alkaliated amino acid complexes.

  12. Laboratory measurements of alkali metal containing vapors released during biomass combustion

    SciTech Connect

    Dayton, D.C.; Milne, T.A.

    1996-12-31

    Alkali metals, in particular potassium, have been implicated as key ingredients for enhancing fouling and slagging of heat transfer surfaces in power generating facilities that convert biomass to electricity. When biomass is used as a fuel in boilers, the deposits formed reduce efficiency, and in the worst case lead to unscheduled plant downtime. Blending biomass with other fuels is often used as a strategy to control fouling and slagging problems. Depending on the combustor, sorbents can be added to the fuel mixture to sequester alkali metals. Another possibility is to develop methods of hot gas cleanup that reduce the amount of alkali vapor to acceptable levels. These solutions to fouling and slagging, however, would greatly benefit from a detailed understanding of the mechanisms of alkali release during biomass combustion. Identifying these alkali vapor species and understanding how these vapors enhance deposit formation would also be beneficial. The approach is to directly sample the hot gases liberated from the combustion of small biomass samples in a variable-temperature quartz-tube reactor employing a molecular beam mass spectrometer (MBMS) system. The authors have successfully used this experimental technique to identify alkali species released during the combustion of selected biomass feedstocks used in larger scale combustion facilities. Fuels investigated include lodgepole pine, eucalyptus, poplar, corn stover, switchgrass, wheat straw, rice straw, pistachio shells, almond shells and hulls, wood wastes, waste paper, alfalfa stems, and willow tops.

  13. Electronic and nuclear dynamics in the frustrated photodesorption of alkali atoms from metals

    NASA Astrophysics Data System (ADS)

    Petek, Hrvoje

    2001-03-01

    Electronic and nuclear dynamics of alkali atom covered noble metal surfaces are investigated by the interferometric time-resolved two-photon photoemission technique [1]. Photoinduced charge transfer turns on the repulsive Coulomb force between the alkali atom and the metal surface thereby initiating the expulsion of alkali atoms from the surface. The resulting nuclear motion of alkali atoms is detected through changes in the surface electronic structure. In the extreme case of Cs/Cu(111), the alkali atom motion can be observed for up to 200 fs, which according to a Newton’s law model corresponds to the stretching of the Cu-Cs bond by 0.3 Å [2]. However, wave packet spreading due to the recoil-induced phonon generation retards the desorption process. Systematic dependence of the alkali atom lifetime on the crystal face, the substrate material, and the adsorbate polarizability provides insights into factors that stabilize adsorbates with respect to decay via the resonant charge transfer and inelastic electron-electron scattering [3]. 1 S. Ogawa, H. Nagano, and H. Petek, Phys. Rev. Lett. 82, 1931 (1999). 2 H. Petek, H. Nagano, M. J. Weida, and S. Ogawa, Science 288, 1402 (2000). 3 J. P. Gauyacq et al., Faraday Discuss. Chem. Soc. 117 (2000).

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

    PubMed

    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.

  15. A hetero-alkali-metal version of the utility amide LDA: lithium-potassium diisopropylamide.

    PubMed

    Armstrong, David R; Kennedy, Alan R; Mulvey, Robert E; Robertson, Stuart D

    2013-03-14

    Designed to extend the synthetically important alkali-metal diisopropylamide [N(i)Pr(2); DA] class of compounds, the first example of a hetero-alkali-metallic complex of DA has been prepared as a partial TMEDA solvate. Revealed by an X-ray crystallographic study, its structure exists as a discrete lithium-rich trinuclear Li(2)KN(3) heterocycle, with TMEDA only solvating the largest of the alkali-metals, with the two-coordinate lithium atoms being close to linearity [161.9(2)°]. A variety of NMR spectroscopic studies, including variable temperature and DOSY NMR experiments, suggests that this new form of LDA maintains its integrity in non-polar hydrocarbon solution. This complex thus represents a rare example of a KDA molecule which is soluble in non-polar medium without the need for excessive amounts of solubilizing Lewis donor being added.

  16. Magic wavelengths for the np-ns transitions in alkali-metal atoms

    SciTech Connect

    Arora, Bindiya; Safronova, M. S.; Clark, Charles W.

    2007-11-15

    Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np{sub 1/2}, np{sub 3/2} states and a large number of excited states are considered in these calculations and their accuracy is evaluated. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali-metal atoms. We find 'magic' wavelengths in alkali-metal atoms for which the ns and np{sub 1/2} and np{sub 3/2} atomic levels have the same ac Stark shifts, which facilitates state-insensitive optical cooling and trapping.

  17. CONTROL ROD ALLOY CONTAINING NOBLE METAL ADDITIONS

    DOEpatents

    Anderson, W.K.; Ray, W.E.

    1960-05-01

    Silver-base alloys suitable for use in the fabrication of control rods for neutronic reactors are given. The alloy consists of from 0.5 wt.% to about 1.5 wt.% of a noble metal of platinum, ruthenium, rhodium, osmium, or palladium, up to 10 wt.% of cadmium, from 2 to 20 wt.% indium, the balance being silver.

  18. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, A.K.

    1979-07-18

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  19. 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.

  20. Advances in high temperature components for AMTEC (Alkali Metal Thermal-To-Electric Converter)

    NASA Astrophysics Data System (ADS)

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

    1991-07-01

    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), 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.

  1. Probing alkali metal-pi interactions with the side chain residue of tryptophan.

    PubMed

    Hu, Jiaxin; Barbour, Leonard J; Gokel, George W

    2002-04-16

    Feeble forces play a significant role in the organization of proteins. These include hydrogen bonding, hydrophobic interactions, salt bridge formation, and steric interactions. The alkali metal cation-pi interaction is a force of potentially profound importance but its consideration in biology has been limited by the lack of experimental evidence. Our previous studies of cation-pi interactions with Na(+) and K(+) involved the side arms of tryptophan (indole), tyrosine (phenol), and phenylalanine (benzene) as the arene donors. The receptor system possesses limiting steric constraints. In this report, we show that direct interactions between alkali metals and arenes occur at or within the van der Waals contact distance.

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

    NASA Astrophysics Data System (ADS)

    Sahin, H.; Peeters, F. M.

    2013-02-01

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

  3. The interaction of hydrogen with metal alloys

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Montano, J. W.

    1991-01-01

    Hydrogen diffusion coefficients were measured for several alloys, and these were determined to be about the same at 25 C for all alloys investigated. The relation of structure, both metallurgical and crystallographic, to the observed hydrogen distribution on charging was investigated, as well as the role of hydride formation in the hydrogen resistance of metal alloys. An attempt was made to correlate the structures and compositions of metal alloys as well as other parameters with the ratios of their notched tensile strengths in hydrogen to that in helium, R(H2/He), which are believed to represent a measure of their hydrogen resistance. Evidence supports the belief that hydrogen permeability and hydrogen resistance are increased by smaller grain sizes for a given alloy composition.

  4. 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.

  5. 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.

  6. Rare Gas - Alkali Metal Coadsorption on Ag(111): Using Rare Gases as 2D Manometers

    NASA Astrophysics Data System (ADS)

    Diehl, Renee D.; Leatherman, Gerald S.; Vidali, G.

    1996-03-01

    The adsorption of Ar, Kr or Xe onto Ag(111) results in incommensurate overlayers which are aligned with the substrate. However, by preadsorbing a small amount of alkali metal first, it is possible to form rotated islands of rare gases. The rotation angles of these islands do not agree with the predictions of the first-order Novaco-McTague theory for rotational epitaxy, nor do they exactly follow the predictions of geometrical theories. However, the other thermodynamic properties of these layers are essentially identical to those on the clean surface. With higher precoverages of potassium, the potassium-rare gas interaction remains repulsive and rare gases form island structures within the dispersed alkali layers. Since the rare gas overlayers are in equilibrium with the potassium and the thermodynamics of rare gases on clean Ag(111) have already been very well characterized( J. Unguris, L. W. Bruch, E. R. Moog and M. B. Webb, Surf. Sci. 87 (1979) 415; 109 (1981) 522.) it is possible to measure the spreading pressure of the alkali as a function of coverage and therefore to deduce information about the coverage- dependent alkali-alkali and alkali-substrate interactions.

  7. Theoretical study on the adsorption of carbon dioxide on individual and alkali-metal doped MOF-5s

    NASA Astrophysics Data System (ADS)

    Ha, Nguyen Thi Thu; Lefedova, O. V.; Ha, Nguyen Ngoc

    2016-01-01

    Density functional theory (DFT) calculations were performed to investigate the adsorption of carbon dioxide (CO2) on metal-organic framework (MOF-5) and alkali-metal (Li, K, Na) doped MOF-5s. The adsorption energy calculation showed that metal atom adsorption is exothermic in MOF-5 system. Moreover, alkali-metal doping can significantly improve the adsorption ability of carbon dioxide on MOF-5. The best influence is observed for Li-doping.

  8. Synthetic receptors as models for alkali metal cation- binding sites in proteins

    NASA Astrophysics Data System (ADS)

    de Wall, Stephen L.; Meadows, Eric S.; Barbour, Leonard J.; Gokel, George W.

    2000-06-01

    The alkali metal cations Na+ and K+ have several important physiological roles, including modulating enzyme activity. Recent work has suggested that alkali metal cations may be coordinated by systems, such as the aromatic amino acid side chains. The ability of K+ to interact with an aromatic ring has been assessed by preparing a family of synthetic receptors that incorporate the aromatic side chains of phenylalanine, tyrosine, and tryptophan. Thesereceptors are constructed around a diaza-18-crown-6 scaffold, which serves as the primary binding site for an alkali metal cation. The ability of the aromatic rings to coordinate a cation was determined by crystallizing each of the receptors in the presence of K+ and by solving the solid state structures. In all cases, complexation of K+ by the pi system was observed. When possible, the structures of the unbound receptors also were determined for comparison. Further proof that the aromatic ring makes an energetically favorable interaction with the cation was obtained by preparing a receptor in which the arene was perfluorinated. Fluorination of the arene reverses the electrostatics, but the aromaticity is maintained. The fluorinated arene rings do not coordinate the cation in the solid state structure of the K+ complex. Thus, the results of the predicted electrostatic reversal were confirmed. Finally, the biological implications of the alkali metal cation-pi interaction are addressed.

  9. Unidirectional thermal expansion in KZnB3O6: role of alkali metals.

    PubMed

    Lou, Yanfang; Li, Dandan; Li, Zhilin; Zhang, Han; Jin, Shifeng; Chen, Xiaolong

    2015-12-14

    The driving force of the unidirectional thermal expansion in KZnB3O6 has been studied experimentally and theoretically. Our results show that the low-energy vibrational modes of alkali metals play a crucial role in this unusual thermal behavior. PMID:26515521

  10. 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).

  11. 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.

  12. 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.

  13. Affinity Capillary Electrophoresis Applied to Investigation of Valinomycin Complexes with Ammonium and Alkali Metal Ions.

    PubMed

    Štěpánová, Sille; Kašička, Václav

    2016-01-01

    This chapter deals with the application of affinity capillary electrophoresis (ACE) to investigation of noncovalent interactions (complexes) of valinomycin, a macrocyclic dodecadepsipeptide antibiotic ionophore, with ammonium and alkali metal ions (lithium, sodium, potassium, rubidium, and cesium). The strength of these interactions was characterized by the apparent binding (stability, association) constants (K b) of the above valinomycin complexes using the mobility shift assay mode of ACE. The study involved measurements of effective electrophoretic mobility of valinomycin at variable concentrations of ammonium or alkali metal ions in the background electrolyte (BGE). The effective electrophoretic mobilities of valinomycin measured at ambient temperature and variable ionic strength were first corrected to the reference temperature 25 °C and constant ionic strength (10 or 25 mM). Then, from the dependence of the corrected valinomycin effective mobility on the ammonium or alkali metal ion concentration in the BGE, the apparent binding constants of the valinomycin-ammonium or valinomycin-alkali metal ion complexes were determined using a nonlinear regression analysis. Logarithmic form of the binding constants (log K b) were found to be in the range of 1.50-4.63, decreasing in the order Rb(+) > K(+) > Cs(+) > > Na(+) > NH4 (+) ~ Li(+). PMID:27473493

  14. Cation-network interactions in binary alkali metal borate glasses. A far-infrared study

    SciTech Connect

    Kamitsos, E.I.; Karakassides, M.A.; Chryssikos, G.D.

    1987-10-22

    The far-infrared spectra of compositions probing the glass-forming regions of all five binary alkali metal borate systems chi M/sub 2/O x (1 - chi)B/sub 2/O/sub 3/ (0 < chi less than or equal to 0.40, M = Na; and 0 < chi less than or equal to 0.35, M = K, Rb, Cs) have been measured and analyzed to systematically study the alkali metal cation-network interactions and their compositional dependence. Band deconvolution of the measured spectra showed the presence of two distinct distributions of alkali metal cation sites in Li, Na, and K glasses. Similar results have been obtained for rubidium and cesium borate glasses of compositions chi > 0.25. One distribution of cation sites has been observed for the lower alkali metal content Rb and Cs glasses. The fractions of cations in the two different network sites have also been evaluated. The squares of the frequencies of the cation-motion bands were found to vary linearly with composition, and exhibit kinks at chi similarly ordered 20, for all but the Cs glasses. This behavior was explained on the basis of the network structural changes known to occur at this composition.

  15. Croconic acid and alkali metal croconate salts: some new insights into an old story.

    PubMed

    Braga, Dario; Maini, Lucia; Grepioni, Fabrizia

    2002-04-15

    The solid-state structures of a series of alkali metal salts of the croconate dianion (C(5)O(5)(2-)) and of croconic acid (H(2)C(5)O(5)) have been determined. The alkali metal croconates were obtained by ring contraction of rhodizonic acid (H(2)C(6)O(6)), upon treatment with alkali metal hydroxides and recrystallisation from water. The novel species Na(2)C(5)O(5) x 2H(2)O, Rb(2)C(5)O(5) and Cs(2)C(5)O(5), as well as the mixed hydrogencroconate/croconate salt K(3)(HC(5)O(5))(C(5)O(5)) small middle dot2 H(2)O are described and compared with the Li(+), K(+) and NH(4)(+) salts. Single crystals of croconic acid were obtained by crystallisation of croconic acid in the presence of HCl. Crystal structure determinations showed that the C(5)O(5)(2-) ions tend to organize themselves in columns. The interplanar separations lie in the narrow range 3.12-3.42 A and do not necessarily reflect the presence of pi-stacking interactions. It is argued that the small interplanar separation is the result of a compromise between packing of flat croconate units and the spherical cations together with the water molecules that fill the coordination spheres of the alkali metal atoms. PMID:11933108

  16. Desktop Prototyping of Metals and Alloys

    SciTech Connect

    Alexander, J.H.

    2000-03-30

    It has been shown possible to prepare nanoscale nickel oxide by the NRC plasma process. Dispersion were successfully made from the nickel oxide that could be ink-jetted using Sanders International ModelMaker equipment. Ink-jetted layers were sintered to nickel metal thus demonstrating the feasibility of desktop prototyping of metal and alloy miniature components.

  17. a Theory of the Metallization of Semiconductor Surfaces by Alkali Atoms.

    NASA Astrophysics Data System (ADS)

    Te, Ronald Lim

    Experimental evidence suggest that alkali metal atoms adsorbed on a semiconductor substrate undergo a transition from insulating to metallic at low coverage. The electrons in the adlayer initially occupy isolated exponentially localized atomic orbitals, and become metallic with increasing coverage. Several investigations have shown that the onset of metallization occurs at less than a quarter of a monolayer. Interpretation of second-harmonic data, where the signal increases sharply at 1/6 monolayer, suggests a metallization transition due to the delocalization of surface electrons. This dissertation provides a theoretical framework for understanding the metallization of alkali overlayers. The adlayer is simulated using a rectangular lattice with more than 80,000 sites that are randomly occupied by atomic-like orbitals up to densities commensurate with the different coverages. A new computational technique called dynamic recursion was developed to handle calculations with large numbers of basis orbitals. Each alkali orbital is taken to have the same on-site energy; however, the orbital interactions involve several nearest neighbors and are an exponentially decreasing function of the orbitals' separation. This model gives a tight-binding Hamiltonian with random off-diagonal disorder. An investigation of states at the Fermi level shows a sharp transition between strongly and weakly localized states as a function of coverage. This numerically observed transition is indicative of an Anderson-type metal-insulator transition where disorder causes states of different degrees of localization to cross the Fermi level. The Hamiltonian studied exhibits a delocalization transition for states at the Fermi level, and is proposed as a model for the metallization of the alkali metal atoms adsorbed on a semiconductor substrate. These results are consistent with other work which show the existence of a mobility edge that separates exponentially localized from power-law localized

  18. 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.

  19. Alkali Metal Carbenoids: A Case of Higher Stability of the Heavier Congeners.

    PubMed

    Molitor, Sebastian; Gessner, Viktoria H

    2016-06-27

    As a result of the increased polarity of the metal-carbon bond when going down the group of the periodic table, the heavier alkali metal organyl compounds are generally more reactive and less stable than their lithium congeners. We now report a reverse trend for alkali metal carbenoids. Simple substitution of lithium by the heavier metals (Na, K) results in a significant stabilization of these usually highly reactive compounds. This allows their isolation and handling at room temperature and the first structure elucidation of sodium and potassium carbenoids. The control of stability was used to control reactivity and selectivity. Hence, the Na and K carbenoids act as selective carbene-transfer reagents, whereas the more labile lithium systems give rise to product mixtures. Additional fine tuning of the M-C interaction by means of crown ether addition further allows for control of the stability and reactivity. PMID:27100278

  20. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  1. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  2. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  3. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  4. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  5. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  6. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  7. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver,...

  8. Theory of magic optical traps for Zeeman-insensitive clock transitions in alkali-metal atoms

    SciTech Connect

    Derevianko, Andrei

    2010-05-15

    Precision measurements and quantum-information processing with cold atoms may benefit from trapping atoms with specially engineered, 'magic' optical fields. At the magic trapping conditions, the relevant atomic properties remain immune to strong perturbations by the trapping fields. Here we develop a theoretical analysis of magic trapping for especially valuable Zeeman-insensitive clock transitions in alkali-metal atoms. The involved mechanism relies on applying a magic bias B field along a circularly polarized trapping laser field. We map out these B fields as a function of trapping laser wavelength for all commonly used alkalis. We also highlight a common error in evaluating Stark shifts of hyperfine manifolds.

  9. Characteristic thermoluminescence of gamma-irradiated alumina ceramics doped with some alkali metals

    NASA Astrophysics Data System (ADS)

    Henaish, B. A.; El-Agrami, A. M.; Abdel-Fattah, W. I.; Osiris, W. G.

    1994-07-01

    Thermoluminescence properties of pure Al2O3-ceramic discs doped with some oxides of alkali metals and B were investigated. Two groups of samples were studied: one with a low concentration of B and alkali oxides and the other with higher concentration. The first group shows a relatively higher stability and better reproducibility for γ-radiation and neutron-induced TL, which could be utilized in mixed radiation field dosimetry. The main disadvantage of these TL-materials is the relatively high rate of signal fading. A simple course of post irradiation heat annealing is proposed to overcome this drawback.

  10. Metal alloy coatings and methods for applying

    DOEpatents

    Merz, Martin D.; Knoll, Robert W.

    1991-01-01

    A method of coating a substrate comprises plasma spraying a prealloyed feed powder onto a substrate, where the prealloyed feed powder comprises a significant amount of an alloy of stainless steel and at least one refractory element selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The plasma spraying of such a feed powder is conducted in an oxygen containing atmosphere and forms an adherent, corrosion resistant, and substantially homogenous metallic refractory alloy coating on the substrate.

  11. First-principles-based simulation of interlayer water and alkali metal ions in weathered biotite

    NASA Astrophysics Data System (ADS)

    Ikeda, Takashi

    2016-09-01

    We performed first-principles-based simulations of weathered biotites (WBs) including alkali metal ions to investigate the adsorption states of interlayer cations and the cation/water distribution in their interlayer. Our simulations suggest that the inclusion of Fe3+ ions in octahedral sheets of WBs alters significantly the vibrational states, the adsorption states of alkali ions, and the cation/water distribution in our WBs. The Al-O bond cleavage suggested to occur in Fe3+-rich regions of WBs upon the H2O adsorption on Al3+ in tetrahedral sheets enhances greatly the dipole moment of adsorbed H2O molecules, thus enhancing the preference for aggregating inner-sphere complexes of heavy alkali ions particularly Cs+.

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

    DOEpatents

    Gordon, John Howard; Alvare, Javier

    2016-09-13

    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 one 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.

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

    PubMed

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

    2016-03-18

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

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

    PubMed

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

    2016-03-18

    Can cyclen (1,4,7,10-tetraazacyclododecane) bind alkali metal azides? This question is addressed by studying the geometric and electronic structures of the alkali metal azide-cyclen [M(cyclen)N3] complexes using density functional theory (DFT). The effects of adding a second cyclen ring to form the sandwich alkali metal azide-cyclen [M(cyclen)2N3] complexes are also investigated. N3(-) is found to bind to a M(+) (cyclen) template to give both end-on and side-on structures. In the end-on structures, the terminal nitrogen atom of the azide group (N1) bonds to the metal as well as to a hydrogen atom of the cyclen ring through a hydrogen bond in an end-on configuration to the cyclen ring. In the side-on structures, the N3 unit is bonded (in a side-on configuration to the cyclen ring) to the metal through the terminal nitrogen atom of the azide group (N1), and through the other terminal nitrogen atom (N3) of the azide group by a hydrogen bond to a hydrogen atom of the cyclen ring. For all the alkali metals, the N3-side-on structure is lowest in energy. Addition of a second cyclen unit to [M(cyclen)N3] to form the sandwich compounds [M(cyclen)2N3] causes the bond strength between the metal and the N3 unit to decrease. It is hoped that this computational study will be a precursor to the synthesis and experimental study of these new macrocyclic compounds; structural parameters and infrared spectra were computed, which will assist future experimental work. PMID:26880648

  15. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  16. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    PubMed

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals.

  17. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    PubMed

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals. PMID:26005925

  18. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    PubMed

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space. PMID:27178415

  19. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    PubMed

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space.

  20. Metals and Alloys Material Stabilization Process Plan

    SciTech Connect

    RISENMAY, H.R.; BURK, R.A.

    2000-05-18

    This Plan outlines the process for brushing metal and alloys in accordance with the path forward discussed in the Integrated Project Management Plan for the Plutonium Finishing Plant Stabilization and Deactivation Project, HNF-3617, and requirements set forth in the Project Management Plan for Materials Stabilization, HNF-3605. This plan provides the basis for selection of the location to process, the processes involved, equipment to be used, and the characterization of the contents of the can. The scope of the process is from retrieval of metals and alloys from storage to transfer back to storage in a repackaged configuration.

  1. High temperature, oxidation resistant noble metal-Al alloy thermocouple

    NASA Technical Reports Server (NTRS)

    Smialek, James L. (Inventor); Gedwill, Michael G. (Inventor)

    1994-01-01

    A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

  2. The oxidation of metals and alloys

    NASA Technical Reports Server (NTRS)

    Scheil, Erich

    1952-01-01

    This paper reviews the various types of oxidation processes occurring with pure metals and gives explanations for the varying time-temperature-oxidation rate relations that exist for copper, tungsten, zinc, cadmium, and tantalum. The effect of shape and crystal structure on oxidation is discussed. Principles derived are applied to the oxidation of alloys.

  3. Calculation of radiative corrections to hyperfine splittings in the neutral alkali metals

    SciTech Connect

    Sapirstein, J.; Cheng, K.T.

    2003-02-01

    The radiative correction to hyperfine splitting in hydrogen is dominated by the Schwinger term, {alpha}/2{pi} E{sub F}, where E{sub F} is the lowest-order hyperfine splitting. Binding corrections to this term, which enter as powers and logarithms of Z{alpha}, can be expected to be increasingly important in atoms with higher nuclear charge Z. Methods that include all orders of Z{alpha}, developed first to study highly charged ions, are adapted to the study of the neutral alkali metals, lithium through francium. It is shown that the use of the Schwinger term alone to account for radiative corrections to hyperfine splittings becomes qualitatively incorrect for the heavier alkali metals.0.

  4. Reactions between cold methyl halide molecules and alkali-metal atoms

    SciTech Connect

    Lutz, Jesse J.; Hutson, Jeremy M.

    2014-01-07

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH{sub 3}X (X = F, Cl, Br, I) and alkali-metal atoms A (A = Li, Na, K, Rb) using high-level ab initio calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, CH{sub 3}X + A → CH{sub 3} + AX. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow.

  5. An Aqueous Redox Flow Battery Based on Neutral Alkali Metal Ferri/ferrocyanide and Polysulfide Electrolytes

    SciTech Connect

    Wei, Xiaoliang; Xia, Gordon; Kirby, Brent W.; Thomsen, Edwin C.; Li, Bin; Nie, Zimin; Graff, Gordon L.; Liu, Jun; Sprenkle, Vincent L.; Wang, Wei

    2015-11-13

    Aiming to explore low-cost redox flow battery systems, a novel iron-polysulfide (Fe/S) flow battery has been demonstrated in a laboratory cell. This system employs alkali metal ferri/ferrocyanide and alkali metal polysulfides as the redox electrolytes. When proper electrodes, such as pretreated graphite felts, are used, 78% energy efficiency and 99% columbic efficiency are achieved. The remarkable advantages of this system over current state-of-the-art redox flow batteries include: 1) less corrosive and relatively environmentally benign redox solutions used; 2) excellent energy and utilization efficiencies; 3) low cost for redox electrolytes and cell components. These attributes can lead to significantly reduced capital cost and make the Fe/S flow battery system a promising low-cost energy storage technology. The major drawbacks of the present cell design are relatively low power density and possible sulfur species crossover. Further work is underway to address these concerns.

  6. Electronic states of alkali metal-NTCDA complexes: A DFT study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2015-10-01

    Structures and electronic states of organic-inorganic compound of 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) with alkali metals, Mn(NTCDA) (Mdbnd Li and Na, n = 0-2), have been investigated by means of hybrid density functional theory (DFT) calculations. From the DFT calculations, it was found that the electronic state of the complex at the ground state is characterized by a charge-transfer state expressed by (M)+(NTCDA)-. The alkali metals were bound equivalently to the carbonyl oxygen and ether oxygen atoms of NTCDA. The Cdbnd O double bond character of NTCDA was changed to a C-O single bond like character by the strong interaction of M to the Cdbnd O and O sites. This change was the origin of the red-shift of the IR spectrum. The UV-vis absorption spectra of Mn(NTCDA) were theoretically predicted on the basis of theoretical results.

  7. An optically trapped mixture of alkali-metal and metastable helium atoms

    NASA Astrophysics Data System (ADS)

    Flores, Adonis; Mishra, Hari Prasad; Vassen, Wim; Knoop, Steven

    2016-05-01

    Ultracold collisions between alkali-metal and metastable triplet helium (He*) atoms provide the opportunity to study Feshbach resonances in the presence of a strong loss channel, namely Penning ionization, which strongly depends on the internal spin-states of the atoms. Recently we have realized the first optically trapped alkali-metal-metastable helium mixture. To prepare the ultracold 87 Rb+4 He* mixture in a single beam optical dipole trap (ODT), we apply evaporative cooling in a strong quadrupole magnetic trap (QMT) for both species and subsequent transfer to the ODT via a hybrid trap. We will present lifetime measurements of different spin-state mixtures, testing the application of the universal loss model to this interesting multichannel collision system.

  8. 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.

  9. 'Doubly Magic' Conditions in Magic-Wavelength Trapping of Ultracold Alkali-Metal Atoms

    SciTech Connect

    Derevianko, Andrei

    2010-07-16

    In experiments with trapped atoms, atomic energy levels are shifted by the trapping optical and magnetic fields. Regardless of this strong perturbation, precision spectroscopy may be still carried out using specially crafted, 'magic' trapping fields. Finding these conditions for particularly valuable microwave transitions in alkali-metal atoms has so far remained an open challenge. Here I demonstrate that the microwave transitions in alkali-metal atoms may be indeed made impervious to both trapping laser intensity and fluctuations of magnetic fields. I consider driving multiphoton transitions between the clock levels and show that these 'doubly magic' conditions are realized at special values of trapping laser wavelengths and fixed values of relatively weak magnetic fields. This finding has implications for precision measurements and quantum information processing with qubits stored in hyperfine manifolds.

  10. X-ray Compton scattering experiments for fluid alkali metals at high temperatures and pressures

    SciTech Connect

    Matsuda, K. Fukumaru, T.; Kimura, K.; Yao, M.; Tamura, K.; Katoh, M.; Kajihara, Y.; Inui, M.; Itou, M.; Sakurai, Y.

    2015-08-17

    We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  12. van der Waals coefficients for systems with ultracold polar alkali-metal molecules

    NASA Astrophysics Data System (ADS)

    Żuchowski, P. S.; Kosicki, M.; Kodrycka, M.; Soldán, P.

    2013-02-01

    A systematic study of the leading isotropic van der Waals coefficients for the alkali-metal atom+molecule and molecule+molecule systems is presented. Dipole moments and static and dynamic dipole polarizabilities are calculated employing high-level quantum chemistry calculations. The dispersion, induction, and rotational parts of the isotropic van der Waals coefficient are evaluated. The known van der Waals coefficients are then used to derive characteristics essential for simple models of the collisions involving the corresponding ultracold polar molecules.

  13. Polarized Alkali-Metal Vapor with Minute-Long Transverse Spin-Relaxation Time

    NASA Astrophysics Data System (ADS)

    Balabas, M. V.; Karaulanov, T.; Ledbetter, M. P.; Budker, D.

    2010-08-01

    We demonstrate lifetimes of Zeeman populations and coherences in excess of 60 sec in alkali-metal vapor cells with inner walls coated with an alkene material. This represents 2 orders of magnitude improvement over the best paraffin coatings. We explore the temperature dependence of cells coated with this material and investigate spin-exchange relaxation-free magnetometry in a room-temperature environment, a regime previously inaccessible with conventional coating materials.

  14. High field superconductivity in alkali metal intercalates of MoS2

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Flood, D. J.; Wagoner, D. E.; Somoano, R. B.; Rembaum, A.

    1973-01-01

    In the search for better high temperature, high critical field superconductors, a class of materials was found which have layered structures and can be intercalated with various elements and compounds. Since a large number of compounds can be formed, intercalation provides a method of control of superconducting properties. They also provide the possible medium for excitonic superconductivity. Results of magnetic field studies are presented on alkali metal (Na, K, Rb, and Cs) intercalated MoS2 (2H polymorph).

  15. 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.

  16. Isotopic fractionation of alkali earth metals during carbonate precipitation

    NASA Astrophysics Data System (ADS)

    Yotsuya, T.; Ohno, T.; Muramatsu, Y.; Shimoda, G.; Goto, K. T.

    2014-12-01

    The alkaline earth metals such as magnesium, calcium and strontium play an important role in a variety of geochemical and biological processes. The element ratios (Mg/Ca and Sr/Ca) in marine carbonates have been used as proxies for reconstruction of the past environment. Recently several studies suggested that the study for the isotopic fractionation of the alkaline earth metals in marine carbonates has a potentially significant influence in geochemical research fields (e.g. Eisenhauer et al., 2009). The aim of this study is to explore the influence of carbonate polymorphs (Calcite and Aragonite) and environmental factors (e.g., temperature, precipitation rate) on the level of isotopic fractionation of the alkaline earth metals. We also examined possible correlations between the level of isotopic fractionation of Ca and that of other alkaline earth metals during carbonate precipitation. In order to determine the isotope fractionation factor of Mg, Ca and Sr during carbonate precipitation, calcite and aragonite were synthesized from calcium bicarbonate solution in which the amount of magnesium was controlled based on Kitano method. Calcium carbonates were also prepared from the mixture of calcium chlorite and sodium hydrogen carbonate solutions. The isotope fractionation factors were measured by MC-ICPMS. Results suggested that the level of isotopic fractionation of Mg during carbonate precipitation was correlated with that of Sr and that the change of the carbonate crystal structure could make differences of isotopic fractionations of Mg and Ca, however no difference was found in the case of Sr. In this presentation, the possible mechanism will be discussed.

  17. Equation of state for solid rare gases and alkali metals under pressure

    NASA Astrophysics Data System (ADS)

    Bonnet, Pierre

    2016-07-01

    This investigation is based on an atomic equation of state which takes into account the excluded volume of the atom being considered. Study of solid rare gases allows following the packing factor of the solid in equilibrium with the gas at different temperatures and of the solid and the liquid in the case of solid-liquid equilibria. The application of a pressure to the solid up to 9800 MPa allows determining the decrease in atomic volume and thus the compressibility. Such a study leads to proposing a new expression through dividing the pressure derivative (as a function of the excluded volume) by the pressure. This new coefficient is a pressure-independent constant but varies with the atom considered. Multiplied by the initial atomic volume, this coefficient has a unique value for all the rare gases. Furthermore, this is also true for the series of alkali metals with however a lower value of the coefficient. The atomic configurations of the two series are very different with one free electron for the alkali metals but closed shells for the rare gases. The alkali metals are therefore more complex than the rare gases. It is worthwhile to note that study of the equilibrium has not required the use of the principles of thermodynamics.

  18. Metal-to-insulator crossover in alkali doped zeolite.

    PubMed

    Igarashi, Mutsuo; Jeglič, Peter; Krajnc, Andraž; Žitko, Rok; Nakano, Takehito; Nozue, Yasuo; Arčon, Denis

    2016-01-01

    We report a systematic nuclear magnetic resonance investigation of the (23)Na spin-lattice relaxation rate, 1/T1, in sodium loaded low-silica X (LSX) zeolite, Nan/Na12-LSX, for various loading levels of sodium atoms n across the metal-to-insulator crossover. For high loading levels of n ≥ 14.2, 1/T1T shows nearly temperature-independent behaviour between 10 K and 25 K consistent with the Korringa relaxation mechanism and the metallic ground state. As the loading levels decrease below n ≤ 11.6, the extracted density of states (DOS) at the Fermi level sharply decreases, although a residual DOS at Fermi level is still observed even in the samples that lack the metallic Drude-peak in the optical reflectance. The observed crossover is a result of a complex loading-level dependence of electric potential felt by the electrons confined to zeolite cages, where the electronic correlations and disorder both play an important role.

  19. Overlay metallic-cermet alloy coating systems

    NASA Technical Reports Server (NTRS)

    Gedwill, M. A.; Levine, S. R.; Glasgow, T. K. (Inventor)

    1984-01-01

    A substrate, such as a turbine blade, vane, or the like, which is subjected to high temperature use is coated with a base coating of an oxide dispersed, metallic alloy (cermet). A top coating of an oxidation, hot corrosion, erosion resistant alloy of nickel, cobalt, or iron is then deposited on the base coating. A heat treatment is used to improve the bonding. The base coating serves as an inhibitor to interdiffusion between the protective top coating and the substrate. Otherwise, the protective top coating would rapidly interact detrimentally with the substrate and degrade by spalling of the protective oxides formed on the outer surface at elevated temperatures.

  20. Alkali metal mediated C-C bond coupling reaction

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto

    2015-02-01

    Metal catalyzed carbon-carbon (C-C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz)2, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz)2, the structure of [Li(Bz)2]- was drastically changed: Bz-Bz parallel form was rapidly fluctuated as a function of time, and a new C-C single bond was formed in the C1-C1' position of Bz-Bz interaction system. In the hole capture, the intermolecular vibration between Bz-Bz rings was only enhanced. The mechanism of C-C bond formation in the electron capture was discussed on the basis of theoretical results.

  1. Alkali metal mediated C–C bond coupling reaction

    SciTech Connect

    Tachikawa, Hiroto

    2015-02-14

    Metal catalyzed carbon-carbon (C–C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz){sub 2}, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz){sub 2}, the structure of [Li(Bz){sub 2}]{sup −} was drastically changed: Bz–Bz parallel form was rapidly fluctuated as a function of time, and a new C–C single bond was formed in the C{sub 1}–C{sub 1}′ position of Bz–Bz interaction system. In the hole capture, the intermolecular vibration between Bz–Bz rings was only enhanced. The mechanism of C–C bond formation in the electron capture was discussed on the basis of theoretical results.

  2. 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.

  3. 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.

  4. Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw

    SciTech Connect

    Thompson, David Neal; Lacey, Jeffrey Alan; Shaw, Peter Gordon

    2002-04-01

    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°C is desirable, corresponding to SiO2:K2O 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.

  5. Energy transfer from PO excited states to alkali metal atoms in the phosphorus chemiluminescence flame

    PubMed Central

    Khan, Ahsan U.

    1980-01-01

    Phosphorus chemiluminescence under ambient conditions of a phosphorus oxidation flame is found to offer an efficient electronic energy transferring system to alkali metal atoms. The lowest resonance lines, 2P3 / 2,½→2S½, of potassium and sodium are excited by energy transfer when an argon stream at 80°C carrying potassium or sodium atoms intersects a phosphorus vapor stream, either at the flame or in the postflame region. The lowest electronically excited metastable 4IIi state of PO or the (PO[unk]PO)* excimer is considered to be the probable energy donor. The (PO[unk]PO)* excimer results from the interaction of the 4IIi state of one PO molecule with the ground 2IIr state of another. Metastability of the donor state is strongly indicated by the observation of intense sensitized alkali atom fluorescence in the postflame region. PMID:16592925

  6. Electrochemical storage cell or battery of the alkali metal and sulfur type

    SciTech Connect

    Weddigen, G.

    1980-09-09

    An electrochemical storage cell or battery is described that has at least one anode filled with a molten alkali metal as the anolyte and at least one cathode chamber filled with a sulfur-containing catholyte substance with the anode chamber and the cathode chamber separated from each other by an alkali-ion-conducting solid electrolyte. To the catholyte substance in the cathode chamber is added a chemical compound of the polar bond type which can charge the sulfur positively while absorbing electrons. This induces mobilization of the sulfur phase in the cathode chamber and prevents major accumulation of liquid sulfur as an insulator. As a result the cell can be repeatedly recharged with large currents to a greater capacity.

  7. Modification of surface properties of copper-refractory metal alloys

    DOEpatents

    Verhoeven, J.D.; Gibson, E.D.

    1993-10-12

    The surface properties of copper-refractory metal (CU-RF) alloy bodies are modified by heat treatments which cause the refractory metal to form a coating on the exterior surfaces of the alloy body. The alloys have a copper matrix with particles or dendrites of the refractory metal dispersed therein, which may be niobium, vanadium, tantalum, chromium, molybdenum, or tungsten. The surface properties of the bodies are changed from those of copper to that of the refractory metal.

  8. Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions [1]. The vibrational FT-IR (in KBr and ATR techniques) and 1H and 13C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg → Ba were compared with series of univalent metal Li → Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.

  9. Building a Chemical Intuition Under Pressure: Prediction of Alkali Metal Polyhydrides and Subhydrides

    NASA Astrophysics Data System (ADS)

    Zurek, Eva

    2013-06-01

    Stabilization of solid phases with unusual combinations or stoichiometries, and unexpected electronic structures may be achieved by applying external pressure. The prediction of these structures using our chemical intuition (developed at 1 atmosphere) would be exceedingly difficult, making automated structure search techniques prudent. For this reason, we have written XtalOpt, an open-source evolutionary algorithm for crystal structure prediction. Whereas at 1 atmosphere the classic alkali hydrides combine in a one-to-one ratio, M+H-, under pressure non-classic stoichiometries MHn(n > 1) and MmH (m > 1) are preferred. For example, theoretical work has predicted that LiH6 and NaH9 become particularly stable phases at about 100 and 25 GPa, respectively. And the potassium, rubidium and cesium polyhydrides all contain the H3-anion, the simplest exaple of a three centered four electron bond. The alkaline-earth polyhydrides are considered as well. Chemical trends relating the stabilization pressure to the ionization potential, and the nature of the hydrogenic sublattice to the strength of the metal-hydride interaction can be made. These hydrogen-rich materials with nontraditional stoichiometries are computed to undergo an insulator to metal transition at pressures attainable in diamond anvil cells. It may be that these systems are superconductors at experimentally achievable pressures. The metal-rich region of the alkali/hydrogen phase diagram under pressure shows that alkali-metal subhydrides may also be stabilized under pressure. We acknowledge the NSF (DMR-1005413) for financial support.

  10. High temperature corrosion by deposits of alkali salts

    SciTech Connect

    Kloewer, J.

    1996-12-01

    In order to understand and predict how corrosion behavior of metallic high temperature materials is affected by deposits of alkali salts, eight commercial high temperature alloys (AISI 314, alloy 800H, alloy 31, AC66, alloy 45-TM, alloy 625, alloy 59 and alloy C-4) coated with alkali sulfates and chlorides (Na{sub 2}SO{sub 4}/KCl) were investigated in both air and in HCl/SO{sub 2}-containing waste incineration environments. The corrosion rates were found to depend sensitively on the alloy composition, especially on the concentration of molybdenum and silicon. Both stainless steels and nickel base alloys without molybdenum were resistant to dissolution by sulfates in air. Molybdenum-containing steels and nickel base alloys, on the other hand, were extremely susceptible to acidic dissolution in sodium sulfate. These high corrosion rates can be attributed to an increase in salt acidity caused by dissolution of MoO{sub 3}. The effect of HCI in the gas atmosphere was contradictory. All alloys without molybdenum suffered severe internal oxidation, when chlorine was present in the gas atmosphere. The corrosion rates of the nickel-molybdenum alloys, however, were decreased when chlorine was added to the gas phase. The highest corrosion resistance to synthetic waste incineration gas in combination with deposits of alkali sulfates and chlorides was found in the nickel base alloys 45 TM and alloy 625.

  11. Alloy metal nanoparticles for multicolor cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Baptista, Pedro V.; Doria, Gonçalo; Conde, João

    2011-03-01

    Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus results in a more accurate indicator of degree of cancerous activity than either locus alone. Metal nanoparticles have been thoroughly used as labels for in vitro identification and quantification of target sequences. We have synthesized nanoparticles with assorted noble metal compositions in an alloy format and functionalized them with thiol-modified ssDNA (nanoprobes). These nanoprobes were then used for the simultaneous specific identification of several mRNA targets involved in cancer development - one pot multicolor detection of cancer expression. The different metal composition in the alloy yield different "colors" that can be used as tags for identification of a given target. Following a non-cross-linking hybridization procedure previously developed in our group for gold nanoprobes, these multicolor nanoprobes were used for the molecular recognition of several different targets including differently spliced variants of relevant genes (e.g. gene products involved in chronic myeloid leukemia BCR, ABL, BCR-ABL fusion product). Based on the spectral signature of mixtures, before and after induced aggregation of metal nanoparticles, the correct identification could be made. Further application to differentially quantify expression of each locus in relation to another will be presented. The differences in nanoparticle stability and labeling efficiency for each metal combination composing the colloids, as well as detection capability for each nanoprobe will be discussed. Additional studies will be conducted towards allele specific expression studies.

  12. Chemical resistance guide for metals and alloys

    SciTech Connect

    1998-12-31

    This guide contains data for 29,000 combinations of corrodents vs. metals, metal alloys, and carbon. Features and specifications include: (1) 963 liquid or dry chemicals, gases, lubricants, household fluids, foods, atmospheres, and other environments are covered; (2) 70 chemical trade names are covered; (3) 500 synonyms of covered chemicals, gases, etc. are indexed to page numbers; (4) corrodents are listed in alphabetical order; (5) data are presented in symbolic format (A, B, C, NR); (6) where known chemical resistance varies with concentration and temperature, data are presented in descending order of concentration and temperature; (7) mechanical, physical, and electrical properties data for each metal are provided; (8) a flex thumb index is provided at the right-hand margin of the right-hand pages to facilitate quick access to the desired data; (9) an electromotive or galvanic series list covering 120 metals, alloys, and carbon is included; (10) machinability ratings for most metals, including some specific S.F.M. rates, is included; (11) creep or stress relaxation rates at various levels of stress, temperature, and time are included; and (12) printed on semigloss, 70 pound, plastic-coated bond paper that last through years of reference.

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

    PubMed

    Rodgers, Mary T; Armentrout, Peter B

    2016-01-01

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

  14. Thermochemical Ablation Therapy of VX2 Tumor Using a Permeable Oil-Packed Liquid Alkali Metal

    PubMed Central

    Guo, Ziyi; Zhang, Qiang

    2015-01-01

    Objective Alkali metal appears to be a promising tool in thermochemical ablation, but, it requires additional data on safety is required. The objective of this study was to explore the effectiveness of permeable oil-packed liquid alkali metal in the thermochemical ablation of tumors. Methods Permeable oil-packed sodium–potassium (NaK) was prepared using ultrasonic mixing of different ratios of metal to oil. The thermal effect of the mixture during ablation of muscle tissue ex vivo was evaluated using the Fluke Ti400 Thermal Imager. The thermochemical effect of the NaK-oil mixture on VX2 tumors was evaluated by performing perfusion CT scans both before and after treatment in 10 VX2 rabbit model tumors. VX2 tumors were harvested from two rabbits immediately after treatment to assess their viability using trypan blue and hematoxylin and eosin (H.E.) staining. Results The injection of the NaK–oil mixture resulted in significantly higher heat in the ablation areas. The permeable oil controlled the rate of heat released during the NaK reaction with water in the living tissue. Perfusion computed tomography and its parameter map confirmed that the NaK–oil mixture had curative effects on VX2 tumors. Both trypan blue and H.E. staining showed partial necrosis of the VX2 tumors. Conclusions The NaK–oil mixture may be used successfully to ablate tumor tissue in vivo. With reference to the controlled thermal and chemical lethal injury to tumors, using a liquid alkali in ablation is potentially an effective and safe method to treat malignant tumors. PMID:25885926

  15. Deriving the Metal and Alloy Networks of Modern Technology.

    PubMed

    Ohno, Hajime; Nuss, Philip; Chen, Wei-Qiang; Graedel, Thomas E

    2016-04-01

    Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals.

  16. Deriving the Metal and Alloy Networks of Modern Technology.

    PubMed

    Ohno, Hajime; Nuss, Philip; Chen, Wei-Qiang; Graedel, Thomas E

    2016-04-01

    Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals. PMID:26927531

  17. 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.

  18. Optical spectra of hot alkali-metal clusters from the random-matrix model

    SciTech Connect

    Akulin, V.M.; Brechignac, C.; Sarfati, A.

    1997-01-01

    We show that the experimentally observed spectra of optical absorption of sodium cluster ions can be explained in the framework of the same random-matrix model, that has been employed earlier [Phys. Rev. Lett. {bold 75}, 220 (1995)] for the ground-state properties of alkali-metal clusters. This approach reveals the effect of cluster symmetry {open_quotes}on average{close_quotes} on the optical-absorption profiles, describes their temperature dependence, and predicts the line shapes of two-photon absorption. {copyright} {ital 1996} {ital The American Physical Society}

  19. Threshold behavior of positronium formation in positron-alkali-metal scattering

    NASA Astrophysics Data System (ADS)

    Lugovskoy, A. V.; Utamuratov, R.; Kadyrov, A. S.; Stelbovics, A. T.; Bray, I.

    2013-04-01

    We consider positron scattering on the alkali-metal atoms of Li, Na, and K at very low energies, where only the elastic scattering and positronium formation in the ground state are the two open channels. Utilizing the recently developed two-center convergent close-coupling method [Lugovskoy, Kadyrov, Bray, and Stelbovics, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.062708 82, 062708 (2010)] we investigate the behavior of the cross sections as the impact energy goes to zero and demonstrate their convergence. The study sets quantitative benchmarks for any rigorous theoretical treatment of the collision problems.

  20. Synthesis, characterization and photocatalytic properties of alkali metals doped tin dioxide

    NASA Astrophysics Data System (ADS)

    Benhebal, Hadj; Chaib, Messaoud; Léonard, Angélique; Lambert, Stéphanie D.; Crine, Michel

    2011-10-01

    In order to improve the photocatalytic properties of tin dioxide, crystallized powders of SnO 2 photocatalysts doped by alkali metals (Li, Na and K) were synthesized by sol-gel process. The physical properties of these materials were characterized by X-ray diffraction, nitrogen adsorption-desorption, Scanning electron microscopy and Ultraviolet-visible diffuse reflection spectroscopy. The photocatalytic tests under UV radiation conducted on four aromatic compounds (phenol, paranitrophenol, pentachlorophenol and benzoic acid) showed that tin dioxide modified by sodium possesses good photocatalytic activity; The Li-doped SnO 2 is moderately active, while modification by potassium does not improve this activity.

  1. Shortcuts for understanding rovibronic spectroscopy of ultracold alkali metal diatomic molecules

    NASA Astrophysics Data System (ADS)

    Stwalley, William C.; Bellos, Michael; Carollo, Ryan; Banerjee, Jayita; Bermudez, Matthew

    2012-08-01

    The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic molecular beam excitation spectra (MB), photoassociation spectra of ultracold atoms (PA), resonance-enhanced multiphoton ionization spectra (REMPI), stimulated Raman transfer (SRT) spectra) are of major current interest. This manuscript summarizes the significant level of understanding of these various spectroscopies, enabled by using simple graphical and semiclassical ideas and shortcuts. Physical realizations of these spectroscopies will be illustrated using the alkali metal diatomic molecules, both homonuclear (e.g. Rb2) and heteronuclear (e.g. KRb).

  2. Electric dipole polarizabilities of Rydberg states of alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Yerokhin, V. A.; Buhmann, S. Y.; Fritzsche, S.; Surzhykov, A.

    2016-09-01

    Calculations of the static electric-dipole scalar and tensor polarizabilities are presented for two alkali-metal atoms, Rb and Cs, for the n S , n P½,3 /2 , and n D3 /2 ,5 /2 states with large principal quantum numbers up to n =50 . The calculations are performed within an effective one-electron approximation, based on the Dirac-Fock Hamiltonian with a semiempirical core-polarization potential. The obtained results are compared with those from a simpler semiempirical approach and with available experimental data.

  3. Laser Peening - A Processing Tool to Strengthen Metals or Alloys

    SciTech Connect

    Chen, H-L; Hackel, L A

    2003-09-01

    Laser peening is an emerging modern process that impresses a compressive stress into the surfaces of metals or alloys. This treatment can reduce the rate of fatigue cracking and stress corrosion cracking in structural metals or alloys needed for aerospace, nuclear power plants, and military applications. Laser peening could also be used to form metals or alloys into precise shapes without their yielding, leaving their surfaces in a crack resistant compressive state.

  4. Metal dusting and carburization resistance of nickel-base alloys

    SciTech Connect

    Kloewer, J.; Grabke, H.J.; Mueller-Lorenz, E.M.; Agarwal, D.C.

    1997-08-01

    Severe material failures caused by so-called metal dusting have been reported during recent years. The reason for these failures were strongly carburizing CO-H{sub 2} gas mixtures such as encountered in chemical plants for the synthesis of hydrocarbons, methanol, ammonia etc. as well as in plants for the reduction of iron ores. The carburization behavior of nine commercial nickel-base alloys and four iron-nickel-chromium alloys was investigated at 650 C in a carburizing H{sub 2}-CO-H{sub 2}O-gas with a carbon activity of a{sub c} {much_gt} 1. The iron-nickel-chromium alloys suffered severe metal dusting after a very short test period. Nickel base alloys were generally less susceptible to metal dusting than iron-base alloys. However, their corrosion behavior was found to depend sensitively on the chromium concentration of the respective alloys. Alloys like alloy 600H, with a chromium concentration of only 16%, suffered wastage rates which were similar to those of the more resistant iron-base alloys. Nickel-base alloys with chromium concentrations of 25% and above, on the other hand, showed no significant evidence of metal dusting even after 10,000 hours of exposure. It was found that these alloys are protected against metal dusting by the formation of a dense, self-healing chromia scale, which prevents the penetration of carbon into the base metal.

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

    PubMed Central

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-01-01

    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]Be2+, [4]Mg2+, [6]Ca2+, [6]Sr2+ and [6]Ba2+, 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 U eq(Na)/U eq(bonded anions) is partially correlated with 〈[6]Na+—O2−〉 (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 [4]- and [6]-coordination, Na+ in [4]- and [6

  6. 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

  7. 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

  8. 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.

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

    SciTech Connect

    Yang, Zhen-Zhen; Jiang, Deen; Zhu, Xiang; Tian, Chengcheng; Brown, Suree; Do-Thanh, Chi-Linh; He, Liang-Nian; Dai, Sheng

    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 chemistry 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Hagedorn, Norman H.

    1993-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Hagedorn, Norman H.

    1991-09-01

    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.

  13. [The Measuring Method of Atomic Polarization of Alkali Metal Vapor Based on Optical Rotation and the Analysis of the Influence Factors].

    PubMed

    Shang, Hui-ning; Quan, Wei; Chen, Yao; Li, Yang; Li, Hong

    2016-02-01

    High sensitivity measurements of inertia and magnetic field could be achieved by utilizing a category of devices, which manipulate the atomic spins in the spin-exchange-relaxation-free regime. The alkali cell which contains the alkali metal vapor is used to sense magnetic field and inertia. The atomic number density of alkali vapor and the polarization of alkali metal vapor are two of the most important parameters of the cell. They play an important role in the research on atomic spins in the spin-exchange-relaxation-free regime. Besides, optical polarization plays an important role in quantum computing and atomic physics. We propose a measurement of alkali vapor polarization and alkali number density by detecting the optical rotation in one system. This method simplifies existing experimental equipment and processes. A constant bias magnetic field is applied and the Faraday rotation angle is detected by a bunch of the probe beam to deduce alkali-metal density. Then the magnetic field is closed and a bunch of the pump laser is utilized to polarize alkali-metal. Again, the probe beam is utilized to obtain the polarization of alkali metal. The alkali density obtained at first is used to deduce the polarization. This paper applies a numerical method to analyze the Faraday rotation and the polarization rotation. According to the numerical method, the optimal wavelength for the experiment is given. Finally, the fluctuation of magnetic field and wavelength on signal analysis are analyzed. PMID:27209720

  14. Silicon halide-alkali metal flames as a source of solar grade silicon. Final report

    SciTech Connect

    Olson, D.B.; Miller, W.J.; Gould, R.K.

    1980-01-01

    The object of this program was to determine the feasibility of using continuous high-temperature reactions of alkali metals and silicon halides to produce silicon in large quantities and of suitable purity for use in the production of photovoltaic solar cells. Equilibrium calculations showed that a range of conditions were available where silicon was produced as a condensed phase but the byproduct alkali metal salt was a vapor. A process was proposed using the vapor phase reaction of Na with SiCl/sub 4/. Low pressure experiments were performed demonstrating that free silicon was produced and providing experience with the construction of reactant vapor generators. Further experiments at higher reagent flow rates were performed in a low temperature flow tube configuration with co-axial injection of reagents. Relatively pure silicon was produced in these experiments. A high temperature graphite flow tube was built and continuous separation of Si from NaCl was demonstrated. A larger-scaled well-stirred reactor was built. Experiments were performed to investigate the compatibility of graphite-based reactor materials of construction with sodium. At 1100 to 1200 K none of these materials were found to be suitable. At 1700 K the graphites performed well with little damage except to coatings of pyrolytic graphite and silicon carbide which were damaged.

  15. Higher-order C{sub n} dispersion coefficients for the alkali-metal atoms

    SciTech Connect

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

    2005-04-01

    The van der Waals coefficients, from C{sub 11} through to C{sub 16} resulting from second-, third-, and fourth-order perturbation theory are estimated for the alkali-metal (Li, Na, K, and Rb) atoms. The dispersion coefficients are also computed for all possible combinations of the alkali-metal atoms and hydrogen. The parameters are determined from sum rules after diagonalizing a semiempirical fixed core Hamiltonian in a large basis. Comparisons of the radial dependence of the C{sub n}/r{sup n} potentials give guidance as to the radial regions in which the various higher-order terms can be neglected. It is seen that including terms up to C{sub 10}/r{sup 10} results in a dispersion interaction that is accurate to better than 1% whenever the inter-nuclear spacing is larger than 20a{sub 0}. This level of accuracy is mainly achieved due to the fortuitous cancellation between the repulsive (C{sub 11},C{sub 13},C{sub 15}) and attractive (C{sub 12},C{sub 14},C{sub 16}) dispersion forces.

  16. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan. Revision 1

    SciTech Connect

    1992-11-01

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

  17. Alkali Metal Control over N–N Cleavage in Iron Complexes

    PubMed Central

    2015-01-01

    Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber–Bosch process, there is still ambiguity about the number of Fe atoms involved during the N–N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe–N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N–N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N–N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2. PMID:25412468

  18. Understanding the insulating nature of alkali-metal/Si(111):B interfaces.

    PubMed

    Fagot-Revurat, Y; Tournier-Colletta, C; Chaput, L; Tejeda, A; Cardenas, L; Kierren, B; Malterre, D; Le Fèvre, P; Bertran, F; Taleb-Ibrahimi, A

    2013-03-01

    We have recently revisited the phase diagram of alkali-metal/Si(111):B semiconducting interfaces previously suggested as the possible realization of a Mott-Hubbard insulator on a triangular lattice. The insulating character of the 2√[3] × 2√[3]R30 surface reconstruction observed at the saturation coverage, i.e. 0.5 ML, has been shown to find its origin in a giant alkali-metal-induced vertical distortion. Low energy electron diffraction, photoemission spectroscopy and scanning tunneling microscopy and spectroscopy experiments coupled with linear augmented plane-wave density functional theory calculations allow a full understanding of the k-resolved band structure, explaining both the inhomogeneous charge transfers into an Si-B hybridized surface state and the opening of a band gap larger than 1 eV. Moreover, √[3] × √[3]R30, 3 × 3 and 2√[3] × 2√[3]R30 surface reconstructions observed as a function of coverage may reveal a filling-controlled transition from a half-filled correlated magnetic material to a strongly distorted band insulator at saturation. PMID:23400003

  19. Influence of addition of alkali metal compounds to calcium carbonate on desulfurization characteristics

    SciTech Connect

    Naruse, Ichiro; Saito, Katsuhiro; Murakami, Takahiro

    1999-07-01

    Limestone is currently supplied as a desulfurizer into bubbling and circulating fluidized bed coal combustors since both combustors are operated at the temperature ranged from 1,073 to 1,173 K, where limestone can be calcined and sulfurized optimally. In the practical boilers, however, the limestone particles are fed to the combustor excessively since the utilization efficiency of CaO produced by the calcination of limestone is low. On the other hand, many kinds of sea-shell are clarified as one of industrial wastes, and also consist of CaCO{sub 3} similar to limestone. Therefore it would be possible for wasted sea-shell to be applied to one of the desulfurizers. In this case the CO{sub 2} produced by calcination of the shell is fixed and recycled naturally in obedience to the ecological law. From this viewpoint, desulfurization characteristics of wasted sea shell have been already studied fundamentally by using a thermobalance as compared with the results obtained by limestone. The results obtained by this study are summarized as follows. (1) The desulfurization activity for wasted sea-shell is much higher than that for limestone. (2) Even if the alkali metal compounds are partially removed from the sea shell, the desulfurization efficiency does not change. (3) The desulfurization activity can be enhanced by adding alkali metal compounds to limestone. Sodium compounds are more effective on the desulfurization efficiency than potassium compounds. Sodium chloride is the best agent among them.

  20. Matrix diffusion of some alkali- and alkaline earth-metals in granitic rock

    SciTech Connect

    Johansson, H.; Byegaard, J.; Skarnemark, G.; Skaalberg, M.

    1997-12-31

    Static through-diffusion experiments were performed to study the diffusion of alkali- and alkaline earth-metals in fine-grained granite and medium-grained Aespoe-diorite. Tritiated water was used as an inert reference tracer. Radionuclides of the alkali- and alkaline earth-metals (mono- and divalent elements which are not influenced by hydrolysis in the pH-range studied) were used as tracers, i.e., {sup 22}Na{sup +}, {sup 45}Ca{sup 2+} and {sup 85}Sr{sup 2+}. The effective diffusivity and the rock capacity factor were calculated by fitting the breakthrough curve to the one-dimensional solution of the diffusion equation. Sorption coefficients, K{sub d}, that were derived from the rock capacity factor (diffusion experiments) were compared with K{sub d} determined in batch experiments using crushed material of different size fractions. The results show that the tracers were retarded in the same order as was expected from the measured batch K{sub d}. Furthermore, the largest size fraction was the most representative when comparing batch K{sub d} with K{sub d} evaluated from the diffusion experiments. The observed effective diffusivities tended to decrease with increasing cell lengths, indicating that the transport porosity decreases with increasing sample lengths used in the diffusion experiments.

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

    PubMed

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

    2014-12-01

    Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber-Bosch process, there is still ambiguity about the number of Fe atoms involved during the N-N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe-N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N-N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N-N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2. PMID:25412468

  2. Researches of the electrotechnical laboratory. No. 973: Study on alkali metal thermoelectric converter

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Negishi, A.; Honda, T.; Fujii, T.; Masuda, T.; Nozaki, K.

    1995-03-01

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting Beta' '- alumina solid electrolyte (BASE) is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies (20 to 40 percent), high power densities (1 W/sq cm), no moving parts, low maintenance requirements, high durability, and efficiency independent of size. Because of these merits, AMTEC is one of the most promising candidate for dispersed small scale power station, remote power station and aerospace power systems. In this paper, the theoretical and experimental studies on the thin film electrodes characteristics, power generating characteristics, cell efficiency, integral electrode with large current lead, porous metal current lead, series connected cells power generation, potassium AMTEC, wick return AMTEC and system analysis for space and grand use are reported.

  3. First-principles study of d0 ferromagnetism in alkali-metal doped GaN

    NASA Astrophysics Data System (ADS)

    Zhang, Yong

    2016-08-01

    The d0 ferromagnetism in GaN has been studied based on density functional theory. Our results show that GaN with sufficient hole become spin-polarized. Alkali-metal doping can introduce holes in GaN. Among them, both of Li- and Na-doping induce ferromagnetism in GaN and Na-doped GaN behaves as half-metallic ferromagnet. Moreover, at a growth temperature of 2000 K under N-rich condition, both concentrations can exceed 18%, which is sufficient to produce detectable macroscopic magnetism in GaN. The Curie temperature of Li- and Na-doped GaN is estimated to be 304 and 740 K, respectively, which are well above room temperature.

  4. The contents of alkali and alkaline earth metals in soils of the southern Cis-Ural region

    NASA Astrophysics Data System (ADS)

    Asylbaev, I. G.; Khabirov, I. K.

    2016-01-01

    The contents and distribution patterns of alkali and alkaline earth metals in soils and rocks of the southern Cis-Ural region were studied. A database on the contents of these metals was developed, the soils were classified with respect to their provision with these metals, and corresponding schematic maps showing their distribution in soils of the region were compiled. It was found that the contents of these metals decrease from east to west (from the Yuryuzan-Aisk Piedmont Plain to the Ufa Plateau and to the Belebeevsk Upland), and their distribution patterns change. Among alkali metals, the highest accumulation in the soils is typical of potassium, sodium, and cesium; among alkaline earth metals, of strontium and barium.

  5. Ab initio interaction potentials and scattering lengths for ultracold mixtures of metastable helium and alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Kedziera, Dariusz; Mentel, Łukasz; Żuchowski, Piotr S.; Knoop, Steven

    2015-06-01

    We have obtained accurate ab initio +4Σ quartet potentials for the diatomic metastable triplet helium+alkali-metal (Li, Na, K, Rb) systems, using all-electron restricted open-shell coupled cluster singles and doubles with noniterative triples corrections CCSD(T) calculations and accurate calculations of the long-range C6 coefficients. These potentials provide accurate ab initio quartet scattering lengths, which for these many-electron systems is possible, because of the small reduced masses and shallow potentials that result in a small amount of bound states. Our results are relevant for ultracold metastable triplet helium+alkali-metal mixture experiments.

  6. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble...

  7. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble...

  8. Tunable magnetocaloric effect in transition metal alloys.

    PubMed

    Belyea, Dustin D; Lucas, M S; Michel, E; Horwath, J; Miller, Casey W

    2015-01-01

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based "high entropy alloys" in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants. PMID:26507636

  9. Bioaccessibility of metals in alloys: evaluation of three surrogate biofluids.

    PubMed

    Hillwalker, Wendy E; Anderson, Kim A

    2014-02-01

    Bioaccessibility in vitro tests measure the solubility of materials in surrogate biofluids. However, the lack of uniform methods and the effects of variable test parameters on material solubility limit interpretation. One aim of this study was to measure and compare bioaccessibility of selected economically important alloys and metals in surrogate physiologically based biofluids representing oral, inhalation and dermal exposures. A second aim was to experimentally test different biofluid formulations and residence times in vitro. A third aim was evaluation of dissolution behavior of alloys with in vitro lung and dermal biofluid surrogates. This study evaluated the bioaccessibility of sixteen elements in six alloys and 3 elemental/metal powders. We found that the alloys/metals, the chemical properties of the surrogate fluid, and residence time all had major impacts on metal solubility. The large variability of bioaccessibility indicates the relevancy of assessing alloys as toxicologically distinct relative to individual metals.

  10. Bioaccessibility of metals in alloys: Evaluation of three surrogate biofluids

    PubMed Central

    Hillwalker, Wendy E.; Anderson, Kim A.

    2014-01-01

    Bioaccessibility in vitro tests measure the solubility of materials in surrogate biofluids. However, the lack of uniform methods and the effects of variable test parameters on material solubility limit interpretation. One aim of this study was to measure and compare bioaccessibility of selected economically important alloys and metals in surrogate physiologically based biofluids representing oral, inhalation and dermal exposures. A second aim was to experimentally test different biofluid formulations and residence times in vitro. A third aim was evaluation of dissolution behavior of alloys with in vitro lung and dermal biofluid surrogates. This study evaluated the bioaccessibility of sixteen elements in six alloys and 3 elemental/metal powders. We found that the alloys/metals, the chemical properties of the surrogate fluid, and residence time all had major impacts on metal solubility. The large variability of bioaccessibility indicates the relevancy of assessing alloys as toxicologically distinct relative to individual metals. PMID:24212234

  11. Triuret as a Potential Hypokalemic Agent: Structure Characterization of Triuret and Triuret-Alkali Metal Adducts by Mass Spectrometric Techniques

    PubMed Central

    Palii, Sergiu P.; Contreras, Cesar S.; Steill, Jeffrey D.; Palii, Stela S.; Oomens, Jos; Eyler, John R.

    2013-01-01

    Triuret (also known as carbonyldiurea, dicarbamylurea, or 2,4-diimidotricarbonic diamide) is a byproduct of purine degradation in living organisms. An abundant triuret precursor is uric acid, whose level is altered in multiple metabolic pathologies. Triuret can be generated via urate oxidation by peroxynitrite, the latter being produced by the reaction of nitric oxide radical with superoxide radical anion. From this standpoint, an excess production of superoxide radical anions could indirectly favor triuret formation; however very little is known about the potential in vivo roles of this metabolite. Triuret’s structure is suggestive of its ability to adopt various conformations and act as a flexible ligand for metal ions. In the current study, HPLC-MS/MS, energy-resolved mass spectrometry, selected ion monitoring, collision-induced dissociation, IRMPD spectroscopy, Fourier transform-ion cyclotron resonance mass spectrometry and computational methods were employed to characterize the structure of triuret and its metal complexes, to determine the triuret-alkali metal binding motif, and to evaluate triuret affinity toward alkali metal ions, as well as its affinity for Na+ and K+ relative to other organic ligands. The most favored binding motif was determined to be a bidentate chelation of triuret with the alkali metal cation involving two carbonyl oxygens. Using the complexation selectivity method, it was observed that in solution triuret has an increased affinity for potassium ions, compared to sodium and other alkali metal ions. We propose that triuret may act as a potential hypokalemic agent under pathophysiological conditions conducive to its excessive formation and thus contribute to electrolyte disorders. The collision- or photo-induced fragmentation channels of deprotonated and protonated triuret, as well as its alkali metal adducts, are likely to mimic the triuret degradation pathways in vivo. PMID:20371222

  12. 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.

  13. Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

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

    SciTech Connect

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

    2010-10-11

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

  15. Dispersion coefficients for H and He interactions with alkali-metal and alkaline-earth-metal atoms

    SciTech Connect

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

    2003-12-01

    The van der Waals coefficients C{sub 6}, C{sub 8}, and C{sub 10} for H and He interactions with the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are determined from oscillator strength sum rules. The oscillator strengths were computed using a combination of ab initio and semiempirical methods. The dispersion parameters generally agree with close to exact variational calculations for Li-H and Li-He at the 0.1% level of accuracy. For larger systems, there is agreement with relativistic many-body perturbation theory estimates of C{sub 6} at the 1% level. These validations for selected systems attest to the reliability of the present dispersion parameters. About half the present parameters lie within the recommended bounds of the Standard and Certain compilation [J. Chem. Phys. 83, 3002 (1985)].

  16. Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide-semiconductor-compatible silicon nanowires

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Jun; Agarwal, Ajay; Buddharaju, Kavitha D.; Singh, Navab; Gao, Zhiqiang

    2007-06-01

    Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide- semiconductor-compatible silicon nanowires (SiNWs) with crown ethers covalently immobilized on their surface are presented. A densely packed organic monolayer terminated with amine groups is introduced to the SiNW surface via hydrosilylation. Amine-modified crown ethers, acting as sensing elements, are then immobilized onto the SiNWs through a cross-linking reaction with the monolayer. The crown ether-functionalized SiNWs recognize Na+ and K+ according to their complexation ability to the crown ethers. The SiNW sensors are highly selective and capable of achieving an ultralow detection limit down to 50nM, over three orders of magnitude lower than that of conventional crown ether-based ion-selective electrodes.

  17. Accelerated decarburization of Fe-C metal alloys

    DOEpatents

    Pal, Uday B.; Sadoway, Donald R.

    1997-01-01

    A process for improving the rate of metal production and FeO utilization in a steelmaking process or a process combining iron-making and steelmaking in a single reactor that uses or generates Fe-C metal alloy droplets submerged in an FeO-containing slag. The process involves discharging a charge build-up (electron accumulation) in the slag at the slag-metal alloy interface by means of an electron conductor connected between the metal alloy droplets and a gas at a gas-slag interface, said gas having an oxygen partial pressure of at least about 0.01 atmosphere.

  18. Accelerated decarburization of Fe-C metal alloys

    DOEpatents

    Pal, U.B.; Sadoway, D.R.

    1997-05-27

    A process is described for improving the rate of metal production and FeO utilization in a steelmaking process or a process combining iron-making and steelmaking in a single reactor that uses or generates Fe-C metal alloy droplets submerged in an FeO-containing slag. The process involves discharging a charge build-up (electron accumulation) in the slag at the slag-metal alloy interface by means of an electron conductor connected between the metal alloy droplets and a gas at a gas-slag interface, said gas having an oxygen partial pressure of at least about 0.01 atmosphere. 2 figs.

  19. Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy through alkali solution treatments.

    PubMed

    Takematsu, E; Katsumata, K; Okada, K; Niinomi, M; Matsushita, N

    2016-05-01

    Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) was performed through three different alkali solution treatments, including the electrochemical (E), hydrothermal (H), and hydrothermal-electrochemical (HE) processes; all of the processes lead to the formation of sodium-contained amorphous titanium oxide layers on TNTZ samples. The TNTZ samples subjected to the E, H, and HE processes exhibit a flat surface, smooth and fine mesh-like structure surface, and rough mesh-like structure surface, respectively. In the bioactive test, namely, simulated body fluid test, apatite inductivity increases as the surface morphology becomes rough. The order of inductivity for the three processes was HE>H>E. The surface chemical composition also affects the apatite induction ability. The surface with fewer niobium species exhibits better apatite inductivity. PMID:26952470

  20. Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy through alkali solution treatments.

    PubMed

    Takematsu, E; Katsumata, K; Okada, K; Niinomi, M; Matsushita, N

    2016-05-01

    Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) was performed through three different alkali solution treatments, including the electrochemical (E), hydrothermal (H), and hydrothermal-electrochemical (HE) processes; all of the processes lead to the formation of sodium-contained amorphous titanium oxide layers on TNTZ samples. The TNTZ samples subjected to the E, H, and HE processes exhibit a flat surface, smooth and fine mesh-like structure surface, and rough mesh-like structure surface, respectively. In the bioactive test, namely, simulated body fluid test, apatite inductivity increases as the surface morphology becomes rough. The order of inductivity for the three processes was HE>H>E. The surface chemical composition also affects the apatite induction ability. The surface with fewer niobium species exhibits better apatite inductivity.

  1. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  2. Sputtering and secondary ion emission properties of alkali metal films and adsorbed monolayers

    SciTech Connect

    Krauss, A R; Gruen, D M

    1980-01-01

    The secondary ion emission of alkali metal adsorbed monlayer and multilayer films has been studied. Profiling with sub-monolayer resolution has been performed by Auger, x-ray photoemission and secondary ion mass spectroscopy. Characteristic differences in the sputtering yields, and ion fraction have been observed which are associated with both the surface bonding properties and the mechanism leading to the formation of secondary ions. By sputtering with a negative bias applied to the sample, positive secondary ions are returned to the surface, resulting in a reduced sputter-induced erosion rate. Comparison with the results obtained with K and Li overlayers sputtered without sample bias provides an experimental value of both the total and secondary ion sputtering yields. The first and second monolayers can be readily identified and the first monolayer exhibits a lower sputtering yield and higher secondary ion fraction. This result is related to adsorption theory and measured values are compared with those obtained by thermal desorption measurements.

  3. 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.

  4. Silicon Halide-alkali Metal Flames as a Source of Solar Grade Silicon

    NASA Technical Reports Server (NTRS)

    Olson, D. B.; Gould, R. K.

    1979-01-01

    A program is presented which was aimed at determining the feasibility of using high temperature reactions of alkali metals and silicon halides to produce low cost solar-grade silicon. Experiments are being conducted to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, and determine the effects of the reactants and/or products on materials of reactor construction. During the current reporting period, the results of heat release experiments were used to design and construct a new type of thick-wall graphite reactor to produce larger quantities of silicon. A reactor test facility was constructed. Material compatibility tests were performed for Na in contact with graphite and several coated graphites. All samples were rapidly degraded at T = 1200K, while samples retained structural strength at 1700K. Pyrolytic graphite coatings cracked and separated from substances in all cases.

  5. Voltammetric studies of porous molybdenum electrodes for the alkali metal thermoelectric converter

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Bankston, C. P.; Khanna, S. K.; Cole, T.

    1986-01-01

    Voltammetry of partially oxidized porous molybdenum alkali metal thermoelectric converter (AMTEC) electrodes from about 600 to 1000 K revealed a series of redox processes within the AMTEC operational voltage range which can be used to establish the electronic and ionic conductivities of these electrodes. Improved estimates of the free energies of formation of Na2Mo3O6, NaMoO2, and Na3MoO4 are obtained. Evidence is provided for the slow corrosive attack by Na2MoO4 on molybdenum. The ionic conductivity of Na2MoO4 is found to be sufficiently large at temperatures of greater than 700 K to explain the observed electrochemical phenomena in addition to the enhanced sodium transport in AMTEC electrodes below the freezing point of Na2MoO4.

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

    SciTech Connect

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

    2006-03-15

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

  7. Spin-exchange frequency shift in alkali-metal-vapor cell frequency standards

    SciTech Connect

    Micalizio, Salvatore; Godone, Aldo; Levi, Filippo; Vanier, Jacques

    2006-03-15

    In this paper we calculate the effect of spin-exchange collisions in alkali-metal vapors. In the framework of the high-energy approximation, we evaluate the spin-exchange cross sections related to the line broadening and to the frequency shift of the ground state hyperfine transition. We do the calculation for the four isotopes, {sup 23}Na, {sup 39}K, {sup 87}Rb, and {sup 133}Cs. The results are used in particular to evaluate the spin-exchange frequency shift in Rb vapor cell frequency standards used in many applications. It turns out that, due to possible fluctuations in the atomic density, spin exchange may affect significantly the medium and long term frequency stability of the frequency standard.

  8. Laboratory studies of alkali metal filter deposition, ultraviolet transmission, and visible blocking.

    PubMed

    Clarke, J T; Skinner, W R; Vincent, M B; Irgang, T; Suratkal, V; Grassl, H; Trauger, J T

    1999-03-20

    Far-ultraviolet alkali metal or Wood's filters have been produced and tested supporting the production of a flight filter for the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Sodium layers 0.5-1-microm thick transmit up to 40% in the ultraviolet while efficiently blocking visible wavelengths. The prevention of visible pinholes is assisted by a clean, sleek-free surface and a cooled substrate during deposition. The coatings are stabilized efficiently by a bismuth overcoating whose transmission spectrum is presented. We also report for the first time, to our knowledge, the first demonstrated long-wavelength cutoff from a lithium filter, with a shorter cutoff wavelength than sodium and potentially higher stability for astronomical imaging. PMID:18305811

  9. 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

  10. Elastic Metal Alloy Refrigerants: Thermoelastic Cooling

    SciTech Connect

    2010-10-01

    BEETIT Project: UMD is developing an energy-efficient cooling system that eliminates the need for synthetic refrigerants that harm the environment. More than 90% of the cooling and refrigeration systems in the U.S. today use vapor compression systems which rely on liquid to vapor phase transformation of synthetic refrigerants to absorb or release heat. Thermoelastic cooling systems, however, use a solid-state material—an elastic shape memory metal alloy—as a refrigerant and a solid to solid phase transformation to absorb or release heat. UMD is developing and testing shape memory alloys and a cooling device that alternately absorbs or creates heat in much the same way as a vapor compression system, but with significantly less energy and a smaller operational footprint.

  11. 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.

  12. 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. PMID:26054963

  13. Titanium-alloy, metallic-fluid heat pipes for space service

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1979-01-01

    Reactivities of titanium limit its long-term terrestrial use for unprotected heat-pipe envelopes to about 870 K (1100 F). But this external thermochemical limitation disappears when considerations shift to space applications. In such hard-vacuum utilization much higher operating temperatures are possible. Primary restrictions in space environment result from vaporization, thermal creep, and internal compatibilities. Unfortunately, a respected head-pipe reference indicates that titanium is compatible only with cesium from the alkali-metal working-fluid family. This problem and others are subjects of the present paper which advocates titanium-alloy, metallic-fluid heat pipes for long-lived, weight-effective space service between 500 and 1300 K (440 and 1880 F).

  14. Atomic scale modelling of hexagonal structured metallic fission product alloys.

    PubMed

    Middleburgh, S C; King, D M; Lumpkin, G R

    2015-04-01

    Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)-making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance.

  15. Atomic scale modelling of hexagonal structured metallic fission product alloys

    PubMed Central

    Middleburgh, S. C.; King, D. M.; Lumpkin, G. R.

    2015-01-01

    Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)—making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance. PMID:26064629

  16. PRODUCTION OF PLUTONIUM METAL

    DOEpatents

    Lyon, W.L.; Moore, R.H.

    1961-01-17

    A process is given for producing plutonium metal by the reduction of plutonium chloride, dissolved in alkali metal chloride plus or minus aluminum chloride, with magnesium or a magnesium-aluminum alloy at between 700 and 800 deg C and separating the plutonium or plutonium-aluminum alloy formed from the salt.

  17. Tunable magnetocaloric effect in transition metal alloys

    PubMed Central

    Belyea, Dustin D.; Lucas, M. S.; Michel, E.; Horwath, J.; Miller, Casey W.

    2015-01-01

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based “high entropy alloys” in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants. PMID:26507636

  18. Tunable magnetocaloric effect in transition metal alloys

    NASA Astrophysics Data System (ADS)

    Belyea, Dustin D.; Lucas, M. S.; Michel, E.; Horwath, J.; Miller, Casey W.

    2015-10-01

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based “high entropy alloys” in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants.

  19. METHOD OF ALLOYING REACTIVE METALS WITH ALUMINUM OR BERYLLIUM

    DOEpatents

    Runnalls, O.J.C.

    1957-10-15

    A halide of one or more of the reactive metals, neptunium, cerium and americium, is mixed with aluminum or beryllium. The mass is heated at 700 to 1200 deg C, while maintaining a substantial vacuum of above 10/sup -3/ mm of mercury or better, until the halide of the reactive metal is reduced and the metal itself alloys with the reducing metal. The reaction proceeds efficiently due to the volatilization of the halides of the reducing metal, aluminum or beryllium.

  20. Room temperature inorganic ``quasi-molten salts`` as alkali-metal electrolytes

    SciTech Connect

    Xu, K.; Zhang, S.; Angell, C.A.

    1996-11-01

    Room temperature inorganic liquids of high ionic conductivity have been prepared by reacting Lewis acid AlCl with sulfonyl chlorides. The mechanism is not clear at this time since a crystal structure study of the 1:1 complex with CH{sub 3}SO{sub 2}Cl (T{sub m} = 30 C) is not consistent with a simple chloride transfer to create AlClO{sub 4}{sup {minus}} anions. The liquid is in a state somewhere between ionic and molecular. A new term quasi-molten salt is adopted to describe this state. A comparably conducting liquid can be made using BCL{sub 3} in place of AlCl{sub 3}. Unlike their organic counterparts based on ammonium cations (e.g., pyridinium or imidazolium) which reduce in the presence of alkali metals, this inorganic class of cation shows great stability against electrochemical reduction (ca. {minus}1.0 V vs. Li{sup +}/Li), with the useful consequence that reversible lithium and sodium metal deposition/stripping can be supported. The electrochemical window for these quasi-salts with AlCl{sub 3} ranges up to 5.0 V, and their room temperature conductivities exceed 10{sup {minus}4} S/cm. They dissolve lithium and sodium tetrachloroaluminates up to mole fraction {approximately} 0.6 at 100 C and intermediate compositions are permanently stable at ambient. The resultant lithium or sodium salt solutions exhibit electrochemical windows of 4.5--5.0 V vs. Li{sup +}/Li or Na{sup +}/Na and show room temperature conductivities of 10{sup {minus}3.0}--10{sup {minus}2.5} S/cm. In preliminary charge/discharge tests, the cell Li/``quasi-ionic liquid electrolyte``/Li{sub 1+x}Mn{sub 2}O{sub 4} showed a discharge capacity of ca. 110 mAh/(g of cathode) and sustained 80% of the initial capacity after 60 cycles, indicating that these quasi-molten salt-based electrolytes are promising candidates for alkali-metal batteries.

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Elucidating the magnetic and superconducting phases in the alkali metal intercalated iron chalcogenides

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Yi, Ming; Tian, Wei; Bourret-Courchesne, Edith; Birgeneau, Robert J.

    2016-02-01

    The complex interdigitated phases have greatly frustrated attempts to document the basic features of the superconductivity in the alkali metal intercalated iron chalcogenides. Here, using elastic neutron scattering, energy-dispersive x-ray spectroscopy, and resistivity measurements, we elucidate the relations of these phases in RbxFeySe2 -zSz . We find (i) the iron content is crucial in stabilizing the stripe antiferromagnetic (AF) phase with rhombic iron vacancy order (y ≈1.5 ) , the block AF phase with √{5 }×√{5 } iron vacancy order (y ≈1.6 ) , and the iron vacancy-free phase (y ≈2 ) ; and (ii) the iron vacancy-free superconducting phase (z =0 ) evolves into an iron vacancy-free metallic phase with sulfur substitution (z >1.5 ) due to the progressive decrease of the electronic correlation strength. Both the stripe AF phase and the block AF phase are Mott insulators. The iron-rich compounds (y >1.6 ) undergo a first order transition from an iron vacancy disordered phase at high temperatures into the √{5 }×√{5 } iron vacancy ordered phase and the iron vacancy-free phase below Ts. Our data demonstrate that there are miscibility gaps between these three phases. The existence of the miscibility gaps in the iron content is a key to understanding the relationship between these complicated phases.

  3. 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.

  4. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    DOEpatents

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  5. Modeling of thermodiffusion in liquid metal alloys.

    PubMed

    Eslamian, Morteza; Sabzi, Fatemeh; Saghir, M Ziad

    2010-11-01

    In this paper following the linear non-equilibrium thermodynamics approach, an expression is derived for the calculation of the thermodiffusion factor in binary liquid metal alloys. The expression is comprised of two terms; the first term accounts for the thermally driven interactions between metal ions, a phenomenon similar to that of the non-ionic binary mixtures, such as hydrocarbons; the second term is called the electronic contribution and is the mass diffusion due to an internal electric field that is induced as a result of the imposed thermal gradient. Both terms are formulated as functions of the net heats of transport. The ion-ion net heat of transport is simulated by the activation energy of viscous flow and the electronic net heat of transport is correlated with the force acting on the ions by the rearrangement of the conduction electrons and ions. A methodology is presented and used to estimate the liquid metal properties, such as the partial molar internal energies, enthalpies, volumes and the activity coefficients used for model validation. The prediction power of the proposed expression along with some other existing thermodiffusion models for liquid mixtures, such as the Haase, Kempers, Drickamer and Firoozabadi formulas are examined against available experimental data obtained on ground or in microgravity environment. The proposed model satisfactorily predicts the thermodiffusion data of mixtures that are composed of elements with comparable melting points. It is also potentially and qualitatively able to predict a sign change in thermodiffusion factor of Na-K liquid mixture. With some speculation, the sign change is attributed to an anomalous change in thermoelectric power of Na-K mixture with composition. PMID:20856973

  6. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

  7. Theory of semiconductor and transition metal alloys

    NASA Astrophysics Data System (ADS)

    Zunger, Alex

    1997-03-01

    There is a lot of talk about computer-aided discoveries/design of new materials, but the simple fact is that even limiting oneself to materials made of just two elements, (e.g., Cu-Au or Si-Ge), and to a substitutional system, there can exist as many as 2^N configurations that include compounds, alloys, superlattices, and impurities. Indeed, even for modest number of sites N, this is an astronomical number. Thus, the conventional energy minimization approach (e.g., first-principles pseudopotentials) for selecting the most stable crystal structure for A_qBq is hopeless if one considers the full 2^N space configurations of A, B on a lattice of N points. Molecular-dynamics is of no help, since it does not explore effectively the space of lattice configurations. Thus, contemporary energy minimization approaches use instead the method of ``rounding-up the usual suspects'': selecting the lowest energy from only a small number of well-known candidate configurations. The potential for missing new and important structures is obviously large. This talk gives an outline of the solution. It addresses the questions of (i) finding the lowest energy configuration of substitutional systems, (ii) calculating their composition-temperature phase diagram, and (iii) their finite-temperature thermodynamic properties, using the first-principles local density approximation (LDA). Mapping of the LDA energies of only 10-20 A_qBq compounds onto an Ising-like ``cluster-expansion'' enables use of lattice statistical mechanics techniques that elegantly solve the above problems. This extends the utility of the LDA from simple, perfectly-ordered compounds to truly complex structures, beyond the reach of direct LDA calculations. I will illustrate the method for semiconductor systems and transition-metal intermetallic systems, showing how previously unsuspected structures and materials are predicted, and how one can calculate free energies, short range-order and phase-diagrams of alloys. See

  8. Chemiresistive sensing with chemically modified metal and alloy nanoparticles.

    PubMed

    Ibañez, Francisco J; Zamborini, Francis P

    2012-01-23

    This review describes the use of chemically modified pure and alloyed metal nanoparticles for chemiresistive sensing applications. Chemically modified metal nanoparticles consist of a pure or alloyed metallic core with some type of chemical coating. Researchers have studied the electronic properties of 1D, 2D, and 3D assemblies of chemically modified metal nanoparticles, and even single individual nanoparticles. The interaction with the analyte alters the conductivity of the sensitive material, providing a signal to measure the analyte concentration. This review focuses on chemiresistive sensing of a wide variety of gas- and liquid-phase analytes with metal nanoparticles coated with organothiols, ions, polymers, surfactants, and biomolecules. Different strategies used to incorporate chemically modified nanoparticles into chemiresistive sensing devices are reviewed, focusing on the different types of metal and alloy compositions, coatings, methods of assembly, and analytes (vapors, gases, liquids, biological materials), along with other important factors.

  9. Microstructures and Mechanical Properties of Irradiated Metals and Alloys

    SciTech Connect

    Zinkle, Steven J

    2008-01-01

    The effects of neutron irradiation on the microstructural evolution of metals and alloys are reviewed, with an emphasis on the roles of crystal structure, neutron dose and temperature. The corresponding effects of neutron irradiation on mechanical properties of metals and alloys are summarized, with particular attention on the phenomena of low temperature radiation hardening and embrittlement. The prospects of developing improved high-performance structural materials with high resistance to radiation-induced property degradation are briefly discussed.

  10. Adsorption of alkali and alkaline-earth metal atoms on the reconstructed graphene-like BN single sheet

    NASA Astrophysics Data System (ADS)

    Hao, Jun-Hua; Wang, Zheng-Jia; Wang, Yu-Fang; Yin, Yu-Hua; Jiang, Run; Jin, Qing-Hua

    2015-12-01

    A graphene-like BN single sheet with absorbed alkali and alkaline-earth metal atoms have been investigated by using a first-principles method within the framework of density functional theory (DFT). The electronic structure of BN sheet with adsorbed metal atoms is mainly determined by the metal electronic state which is near to the Fermi level owing to the wide band gap of pure BN sheet. So, we calculated the adsorption energy, charge transfer and work function after the metal adsorbed on BN sheet. We found that the interaction between the metal atoms and BN surface was very strong, and the stable adsorption site for all the adsorbed atoms concluded was high-coordination surface site (H-center) rather than the surface dangling bond sites from the perspective of simple bond-counting arguments. Our results indicate that the interaction of BN sheet with metal atoms could help in the development of metallic nanoscale devices.

  11. Electronic properties of metal-induced gap states at insulator/metal interfaces: Dependence on the alkali halide and the possibility of excitonic mechanism of superconductivity

    NASA Astrophysics Data System (ADS)

    Arita, Ryotaro; Tanida, Yoshiaki; Kuroki, Kazuhiko; Aoki, Hideo

    2004-03-01

    Motivated from the experimental observation of metal-induced gap states (MIGS) at insulator/metal interfaces by Kiguchi et al. [Phys. Rev. Lett. 90, 196803 (2003)], we have theoretically investigated the electronic properties of MIGS at interfaces between various alkali halides and a metal represented by a jellium with the first-principles density-functional method. We have found that, on top of the usual evanescent state, MIGS generally have appreciable amplitudes on halogen sites with a pz-like character, whose penetration depth (λ) is as large as half the lattice constant of bulk alkali halides. This implies that λ, while little dependent on the carrier density in the jellium, is dominated by the energy gap of the alkali halide, and is scaled by the lattice constant, where λLiF<λLiCl<λLiI. We also propose a possibility of the MIGS working favorably for the exciton-mediated superconductivity, especially in a system where ˜10 Å of metal is sandwiched by alkali halide substrates.

  12. Monte Carlo simulation of nanowires of different metals and two-metal alloys.

    PubMed

    Giménez, M C; Schmicker, Wolfgang

    2011-02-14

    Nanowires of different metals and two-metal alloys have been studied by means of canonical Monte Carlo simulations and the embedded atom method for the interatomic potentials. For nanowires of gold, a relatively stable three-atom-wide chain was observed. The presence of one-atom-wide linear atomic chains is not stable in any case. For two-metal alloy nanowires, the metal with a higher surface energy tends to locate in the inner region of the nanowire.

  13. Effect of sorbed molecules on the resistivity of alkali metal-graphite intercalation compounds

    SciTech Connect

    Akuzawa, Noboru Kunihashi, Yoji; Sato, Yuki; Tsuchiya, Ken-ichi; Matsumoto, Rika

    2007-03-15

    Alkali metal-graphite intercalation compounds with the composition of MC{sub 24} (M=K, Rb, Cs) were prepared by heating a mixture of MC{sub 8} (saturated compound) and graphite sheet (Grafoil) at 350-450 deg. C. The resistivity perpendicular to the layer planes ({rho} {sub c}) of the resulting compounds was determined by the two-terminal method. The anisotropy factor of the resistivity, ({rho} {sub c}/{rho} {sub a}), of KC{sub 24} prepared from Grafoil was {approx}130, being about 1/6-1/10 in magnitude compared with that of KC{sub 24} prepared from highly oriented pyrolytic graphite. The resistivity change during sorption of hydrogen (at 90 K), ethylene (at 194 K) and acetylene (at 194 K) was determined. The resistivity of MC{sub 24} increased with increase of the sorbed amount of H{sub 2}. The magnitude of the increase was in the order KC{sub 24}>RbC{sub 24}>CsC{sub 24}. This resistivity increase was considered to be due to the expansion along c-direction which reduces the charge-transfer interaction between the carbon layers and potassium ions, resulting in the decrease of the density of the conduction electron. The resistivity of MC{sub 24} increased extensively during sorption of C{sub 2}H{sub 4} and C{sub 2}H{sub 2}. It was discussed in connection with the in-plane structural transition and chemical interaction between alkali metal ions and sorbed molecules. - Graphical abstract: The resistivity of MC{sub 24} increased with increase of the sorbed amount of H{sub 2}. The magnitude of the increase was in the order KC{sub 24}>RbC{sub 24}>CsC{sub 24}. This resistivity increase was considered to be due to the expansion along c-direction which reduces the charge-transfer interaction between the carbon layers and potassium ions.

  14. Preparation of decarboxylic-functionalized weak cation exchanger and application for simultaneous separation of alkali, alkaline earth and transition metals.

    PubMed

    Peng, Yahui; Gan, Yihui; He, Chengxia; Yang, Bingcheng; Guo, Zhimou; Liang, Xinmiao

    2016-06-01

    A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a "thiol-ene" click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water. PMID:27130093

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

    PubMed

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

    2016-01-01

    This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described. PMID:26860299

  16. CRC Handbook of Electrical Resistivitives of Binary Metallic Alloys

    SciTech Connect

    Schroder, K.

    1983-01-01

    Material design engineers often require a tabulation of physical properties in order to select the appropriate material for use, while developmental engineers need to be aware of basic principles and systemic trends that can be utilized as a guide for developing future materials and alloys. The trade-off in conductivity that results when metals are replaced by alloys for strength and stability purposes becomes an important consideration for both types of engineers. This handbook presents an extensive, updated and comprehensive compilation of the electrical resistivities of metallic alloys.

  17. Metal-Induced Gap States at Well Defined Alkali-Halide/Metal Interfaces

    NASA Astrophysics Data System (ADS)

    Kiguchi, Manabu; Arita, Ryotaro; Yoshikawa, Genki; Tanida, Yoshiaki; Katayama, Masao; Saiki, Koichiro; Koma, Atsushi; Aoki, Hideo

    2003-05-01

    In order to search for states specific to insulator/metal interfaces, we have studied epitaxially grown interfaces with element-selective near edge x-ray absorption fine structure. An extra peak is observed below the bulk edge onset for LiCl films on Cu and Ag substrates. The nature of chemical bonds as probed by x-ray photoemission spectroscopy and Auger electron spectroscopy remains unchanged, so we regard this as evidence for metal-induced gap states (MIGS) formed by the proximity to a metal, rather than local bonds at the interface. The dependence on the film thickness shows that the MIGS are as thin as one monolayer. An ab initio electronic structure calculation supports the existence of the MIGS that are strongly localized at the interface.

  18. Metal-induced gap states at well defined alkali-halide/metal interfaces.

    PubMed

    Kiguchi, Manabu; Arita, Ryotaro; Yoshikawa, Genki; Tanida, Yoshiaki; Katayama, Masao; Saiki, Koichiro; Koma, Atsushi; Aoki, Hideo

    2003-05-16

    In order to search for states specific to insulator/metal interfaces, we have studied epitaxially grown interfaces with element-selective near edge x-ray absorption fine structure. An extra peak is observed below the bulk edge onset for LiCl films on Cu and Ag substrates. The nature of chemical bonds as probed by x-ray photoemission spectroscopy and Auger electron spectroscopy remains unchanged, so we regard this as evidence for metal-induced gap states (MIGS) formed by the proximity to a metal, rather than local bonds at the interface. The dependence on the film thickness shows that the MIGS are as thin as one monolayer. An ab initio electronic structure calculation supports the existence of the MIGS that are strongly localized at the interface.

  19. A simple approach to metal hydride alloy optimization

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Miller, C. G.; Landel, R. F.

    1976-01-01

    Hildebrand-Scott (1950) solubility parameters can be obtained for metals and alloys by calculating the cohesive energy density (CED), equal to the square of the solubility parameter, and a function of the heat of sublimation and the atomic volume. It is suggested that the solubility parameter permits estimation of the hydrogen storage capacity of an alloy and that alloys with a solubility parameter approximately equal to the parameter for hydrogen will have greater hydrogen storage capacity than other alloys. Equilibrium pressure - temperature relationships for some metal hydrides are presented in conjunction with the calculated solubility parameter and correlated with characteristics which would be useful in hydrogen-powered vehicles. Alloy properties which increase the amount of nonstoichiometric reversible hydrogen absorption are discussed.

  20. Tantalum alloys resist creep deformation at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1966-01-01

    Dispersion-strengthened tantalum-base alloys possess high strength and good resistance to creep deformation at elevated temperatures in high vacuum environments. They also have ease of fabrication, good weldability, and corrosion resistance to molten alkali metals.

  1. Control of metal dusting corrosion in Ni-base alloys.

    SciTech Connect

    Zeng, Z.; Natesan, K.; Energy Technology

    2007-11-01

    Metal dusting is a major issue in plants used in the production of hydrogen-and methanol-reformer systems, and syngas (H{sub 2}/CO mixtures) systems that are pertinent to the chemical and petrochemical industries. Usually, metal dusting corrosion has two stages: incubation and growth resulting in propagation of metal dusting pits. The two stages were studied by scanning electron microscopy and profile mapping to evaluate the scale of the surface oxide in the initiation and propagation of metal dusting attack. The initiation occurs because of the presence of defects, and the propagation is determined by the diffusion of carbon into the alloy. The carbon diffusion pathways can be blocked by periodically oxidizing alloy surface at moderate temperatures in controlled atmospheres. It was concluded that metal dusting degradation can be mitigated by selecting an alloy with a long incubation time and subjecting it to intermediate oxidation.

  2. Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1979-September 1980

    SciTech Connect

    Johnson, I.; Swift, W.M.; Lee, S.H.D.

    1980-10-01

    In the application of pressurized fluidized-bed combustion (PFBC) to the generation of electricity, hot corrosion of the gas turbine (downstream from the combustor) by alkali metal compounds is a potential problem. The objective of this investigation is to develop a method for the removal of gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. The use of a granular bed filter, with either diatomaceous earth or activated bauxite as the bed material, is under study. Breakthrough data are reported on the sorption of gaseous NaCl by activated bauxite. Results are reported for the regeneration of activated bauxite using water leaching and a thermal swing method.

  3. Ground state of the polar alkali-metal-atom-strontium molecules: Potential energy curve and permanent dipole moment

    SciTech Connect

    Guerout, R.; Aymar, M.; Dulieu, O.

    2010-10-15

    In this study, we investigate the structure of the polar alkali-metal-atom-strontium diatomic molecules as possible candidates for the realization of samples of ultracold polar molecular species not yet investigated experimentally. Using a quantum chemistry approach based on effective core potentials and core polarization potentials, we model these systems as effective three-valence-electron systems, allowing for calculation of electronic properties with full configuration interaction. The potential curve and the permanent dipole moment of the {sup 2}{Sigma}{sup +} ground state are determined as functions of the internuclear distance for LiSr, NaSr, KSr, RbSr, and CsSr molecules. These molecules are found to exhibit a significant permanent dipole moment, though smaller than those of the alkali-metal-atom-Rb molecules.

  4. 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

    2015-02-01

    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.

  5. The relationship between molecular structure and biological activity of alkali metal salts of vanillic acid: Spectroscopic, theoretical and microbiological studies

    NASA Astrophysics Data System (ADS)

    Świsłocka, Renata; Piekut, Jolanta; Lewandowski, Włodzimierz

    In this paper we investigate the relationship between molecular structure of alkali metal vanillate molecules and their antimicrobial activity. To this end FT-IR, FT-Raman, UV absorption and 1H, 13C NMR spectra for lithium, sodium, potassium, rubidium and caesium vanillates in solid state were registered, assigned and analyzed. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris, Bacillus subtilis and Candida albicans. In order to evaluate the dependence between chemical structure and biological activity of alkali metal vanillates the statistical analysis was performed for selected wavenumbers from FT-IR spectra and parameters describing microbial activity of vanillates. The geometrical structures of the compounds studied were optimized and the structural characteristics were determined by density functional theory (DFT) using at B3LYP method with 6-311++G** as basis set. The obtained statistical equations show the existence of correlation between molecular structure of vanillates and their biological properties.

  6. Characterization of Adsorbed Alkali Metal Ions in 2:1 Type Clay Minerals from First-Principles Metadynamics.

    PubMed

    Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi

    2015-07-30

    Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two-dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs(+) in the 2:1 type trioctahedral clay minerals with saponite-like compositions, where lighter alkali metal ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs(+) is found to result partially from the capability of recognizing selectively Cs(+) ions at the basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.

  7. Thermophysical Property Measurements of Silicon-Transition Metal Alloys

    NASA Technical Reports Server (NTRS)

    Banish, R. Michael; Erwin, William R.; Sansoucie, Michael P.; Lee, Jonghyun; Gave, Matthew A.

    2014-01-01

    Metals and metallic alloys often have high melting temperatures and highly reactive liquids. Processing reactive liquids in containers can result in significant contamination and limited undercooling. This is particularly true for molten silicon and it alloys. Silicon is commonly termed "the universal solvent". The viscosity, surface tension, and density of several silicon-transition metal alloys were determined using the Electrostatic Levitator system at the Marshall Space Flight Center. The temperature dependence of the viscosity followed an Arrhenius dependence, and the surface tension followed a linear temperature dependence. The density of the melts, including the undercooled region, showed a linear behavior as well. Viscosity and surface tension values were obtain for several of the alloys in the undercooled region.

  8. 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.

  9. 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

  10. Alkali-vapor cell with metal coated windows for efficient application of an electric field

    NASA Astrophysics Data System (ADS)

    Sarkisyan, D.; Sarkisyan, A. S.; Guéna, J.; Lintz, M.; Bouchiat, M.-A.

    2005-05-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no magnetic part. The use of this kind of cell has resulted in an improvement of the signal-to-noise ratio in the measurement of parity violation in cesium vapor underway at ENS, Paris. The technique can be applied to other situations where a brazed assembly would give rise to unacceptably large birefringence in the windows.

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

    NASA Technical Reports Server (NTRS)

    Olson, D. B.; Miller, W. J.; Gould, R. K.

    1980-01-01

    The feasibility of using continuous high-temperature reactions of alkali metals and silicon halides to produce silicon in large quantities and of suitable purity for use in the production of photovoltaic solar cells was demonstrated. Low pressure experiments were performed demonstrating the production of free silicon and providing experience with the construction of reactant vapor generators. Further experiments at higher reagent flow rates were performed in a low temperature flow tube configuration with co-axial injection of reagents and relatively pure silicon was produced. A high temperature graphite flow tube was built and continuous separation of Si from NaCl was demonstrated. A larger scaled well stirred reactor was built. Experiments were performed to investigate the compatability of graphite based reactor materials of construction with sodium. At 1100 to 1200 K none of these materials were found to be suitable. At 1700 K the graphites performed well with little damage except to coatings of pyrolytic graphite and silicon carbide which were damaged.

  12. Atomic many-body effects and Lamb shifts in alkali metals

    NASA Astrophysics Data System (ADS)

    Ginges, J. S. M.; Berengut, J. C.

    2016-05-01

    We present a detailed study of the radiative potential method [V. V. Flambaum and J. S. M. Ginges, Phys. Rev. A 72, 052115 (2005), 10.1103/PhysRevA.72.052115], which enables the accurate inclusion of quantum electrodynamics (QED) radiative corrections in a simple manner in atoms and ions over the range 10 ≤Z ≤120 , where Z is the nuclear charge. Calculations are performed for binding energy shifts to the lowest valence s , p , and d waves over the series of alkali-metal atoms Na to E119. The high accuracy of the radiative potential method is demonstrated by comparison with rigorous QED calculations in frozen atomic potentials, with deviations on the level of 1%. The many-body effects of core relaxation and second- and higher-order perturbation theory on the interaction of the valence electron with the core are calculated. The inclusion of many-body effects tends to increase the size of the shifts, with the enhancement particularly significant for d waves; for K to E119, the self-energy shifts for d waves are only an order of magnitude smaller than the s -wave shifts. It is shown that taking into account many-body effects is essential for an accurate description of the Lamb shift.

  13. Interaction of alkali metals with perylene-3,4,9,10- tetracarboxylic-dianhydride thin films

    SciTech Connect

    Wuesten, J.; Berger, S.; Heimer, K.; Lach, S.; Ziegler, Ch.

    2005-07-01

    n doping of the molecular organic semiconductor perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) is often achieved by use of alkali metals as dopants. This doping process is commonly performed in two steps. In the first the dopant is evaporated onto the surface of the PTCDA film. As it has been believed that the dopant shows an inhomogeneous diffusion profile through the layer with most of the dopant accumulated in the first few layers, a subsequent annealing step has been performed in order to reach a homogeneous distribution of the dopant in the whole layer. In this paper experimental results concerning chemical composition ((angle resolved) X-ray photoemission spectroscopy, secondary-ion-mass spectrometry, Fourier transform infrared spectroscopy), electronic structure (ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy), as well as electrical properties (conductivity, Seebeck coefficient) are shown before and after doping and before and after annealing. These results suggest that the deposited dopant is redistributed and partially removed during the annealing step. A model for the dopant distribution is suggested.

  14. Application of alkali metal-doped carbons for hydrogen recovery and isotope separation.

    PubMed

    Akuzawa, N; Okano, Y; Iwashita, T; Matsumoto, R; Soneda, Y

    2011-10-01

    Hydrogen-sorption isotherms of alkali metal-doped carbons at 77 K were determined for promoting application of these materials as hydrogen-recovery and isotope-separation agent. The hydrogen-sorption behavior of rubidium-doped Grafoil, with composition of RbC24, showed high sorption ability against hydrogen at low pressure. Taking into account the fact that sorption-desorption was fast and reversible, and the equilibrium pressure at half coverage was very low, i.e., 40 Pa, RbC24 prepared from Grafoil is promising as a recovery agent for hydrogen gas at low pressure. The hydrogen (H2)/deuterium(D2)-sorption isotherms of potassium-doped carbons with composition of KC10, prepared from multi wall carbon nanotube (MWCNT) and carbons derived from petroleum cokes with heat-treatment temperatures of 1000 and 1500 degrees C, were also determined. Isotope separation coefficient was estimated from those isotherms. A very large isotope effect was found for KC10 prepared from MWCNT, comparable to those prepared from carbons with heat-treatment temperatures of 1000 or 1500 degrees C. However, a severe problem was found for KC10 (MWCNT) that repetition of the sorption-desorption cycles resulted in the decrease of the sorbed amount of H2 and D2.

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

    PubMed

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

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  16. Mechanical properties and bioactive surface modification via alkali-heat treatment of a porous Ti-18Nb-4Sn alloy for biomedical applications.

    PubMed

    Xiong, Jianyu; Li, Yuncang; Wang, Xiaojian; Hodgson, Peter; Wen, Cui'e

    2008-11-01

    A porous Ti-18 at.%Nb-4 at.%Sn (hereafter, Ti-18Nb-4Sn) alloy was prepared by powder metallurgy. The porous structures were examined by scanning electron microscopy and the phase constituents were analysed by X-ray diffraction. Mechanical properties of the porous alloy were investigated using a compressive test. To enhance the bioactivity of the alloy surface, alkali-heat treatment was used to modify the surface. The bioactivity of the pre-treated alloy sample was investigated using a biomimetic process by soaking the sample into simulated body fluid (SBF). Results indicate that the elastic modulus and plateau stress of the porous Ti-18Nb-4Sn alloy decrease with decreasing relative density. The mechanical properties of the porous alloy can be tailored to match those of human bone. After soaking in SBF for 7 days, a hydroxyapatite layer formed on the surface of the pre-treated porous Ti-18Nb-4Sn alloy. The pre-treated porous Ti-18Nb-4Sn alloy therefore has the potential to be a bioactive implant material. PMID:18524702

  17. Element specificity of ortho-positronium annihilation for alkali-metal loaded SiO{sub 2} glasses

    SciTech Connect

    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 SiO{sub 2} 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.

  18. Effect of the combination of dithiooctanoate monomers and acidic adhesive monomers on adhesion to precious metals, precious metal alloys and non-precious metal alloys.

    PubMed

    Ikemura, Kunio; Kojima, Katsunori; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    This study investigated the effect of the combination of a dithiooctanoate monomer and an acidic adhesive monomer on adhesion to precious metals, precious and non-precious metal alloys. From a selection of four dithiooctanoate monomers and six acidic adhesive monomers, 14 experimental primers containing a combination of 5.0 wt% of a dithiooctanoate monomer and 1.0 wt% of an acidic adhesive monomer in acetone were prepared. Tensile bond strengths (TBSs) of MMA-PMMA/TBBO resin to nine kinds of precious metals, precious metal alloys, and non-precious metal alloys after 2,000 thermal cycles were measured. Results showed that there were no significant differences in TBS among the primers to all the precious and non-precious metal adherends tested (p>0.05). Highest TBS values (46.5-55.8 MPa) for bonding to Au alloy, Au-Ag-Pd alloy, Co-Cr alloy, and Ni-Cr alloy were achieved with the primer which contained 5.0 wt% 10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) and 1.0 wt% 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA). Therefore, 5.0 wt% 10-MDDT and 1.0 wt% 6-MHPA was determined as the optimal combination for bonding to precious metals, precious and non-precious metal alloys.

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

    PubMed

    Inokuchi, Yoshiya; Boyarkin, Oleg V; Ebata, Takayuki; Rizzo, Thomas R

    2012-04-01

    We report UV photodissociation (UVPD) and IR-UV double-resonance spectra of 1,2-dimethoxybenzene (DMB) complexes with alkali metal ions, M(+)·DMB (M = Li, Na, K, Rb, and Cs), in a cold, 22-pole ion trap. The UVPD spectrum of the Li(+) complex shows a strong origin band. For the K(+)·DMB, Rb(+)·DMB, and Cs(+)·DMB complexes, the origin band is very weak and low-frequency progressions are much more extensive than that of the Li(+) ion. In the case of the Na(+)·DMB complex, spectral features are similar to those of the K(+), Rb(+), and Cs(+) complexes, but vibronic bands are not resolved. Geometry optimization with density functional theory indicates that the metal ions are bonded to the oxygen atoms in all the M(+)·DMB complexes. For the Li(+) complex in the S(0) state, the Li(+) ion is located in the same plane as the benzene ring, while the Na(+), K(+), Rb(+), and Cs(+) ions are located off the plane. In the S(1) state, the Li(+) complex has a structure similar to that in the S(0) state, providing the strong origin band in the UV spectrum. In contrast, the other complexes show a large structural change in the out-of-plane direction upon S(1)-S(0) excitation, which results in the extensive low-frequency progressions in the UVPD spectra. For the Na(+)·DMB complex, fast charge transfer occurs from Na(+) to DMB after the UV excitation, making the bandwidth of the UVPD spectrum much broader than that of the other complexes and producing the photofragment DMB(+) ion.

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

    NASA Technical Reports Server (NTRS)

    Garber, Anne E.; Dickens, Ricky E.

    2011-01-01

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

  1. Bone bonding ability of a chemically and thermally treated low elastic modulus Ti alloy: gum metal.

    PubMed

    Tanaka, Masashi; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Kawai, Toshiyuki; Yamaguchi, Seiji; Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Matsuda, Shuichi

    2014-03-01

    The gum metal with composition Ti-36Nb-2Ta-3Zr-0.3O, is free from cytotoxic elements and exhibits a low elastic modulus as well as high mechanical strength. We have previously demonstrated that this gum metal, once subjected to a series of surface treatments--immersion in 1 M NaOH (alkali treatment) and then 100 mM CaCl2, before heating at 700 °C (sample: ACaH-GM), with an optional final hot water immersion (sample: ACaHW-GM)--has apatite-forming ability in simulated body fluid. To confirm the in vivo bioactivity of these treated alloys, failure loads between implants and bone at 4, 8, 16, and 26 weeks after implantation in rabbits' tibiae were measured for untreated gum metal (UT-GM), ACaH-GM and ACaHW-GM, as well as pure titanium plates after alkali and heat treatment (AH-Ti). The ACaH-GM and UT-GM plates showed almost no bonding, whereas ACaHW-GM and AH-Ti plates showed successful bonding by 4 weeks, and their failure loads subsequently increased with time. The histological findings showed a large amount of new bone in contact with the surface of ACaHW-GM and AH-Ti plates, suggesting that the ACaHW treatment could impart bone-bonding bioactivity to a gum metal in vivo. Thus, with this improved bioactive treatment, these advantageous gum metals become useful candidates for orthopedic and dental devices.

  2. Levitation-melting technique for metals and alloys

    NASA Technical Reports Server (NTRS)

    Downey, J. W.

    1969-01-01

    Experimentation resulted in an improved levitation-melting technique for metals and alloys which quickly produces a completly homogeneous melt. Also developed were two levitation coils that permit a wide variety of metals to be levitated in the molten state and a helium quenching method which minimizes contamination and segregation.

  3. Highly polar bonds and the meaning of covalency and ionicity--structure and bonding of alkali metal hydride oligomers.

    PubMed

    Bickelhaupt, F Matthias; Solà, Miquel; Guerra, Célia Fonseca

    2007-01-01

    The hydrogen-alkali metal bond is simple and archetypal, and thus an ideal model for studying the nature of highly polar element-metal bonds. Thus, we have theoretically explored the alkali metal hydride monomers, HM, and (distorted) cubic tetramers, (HM)4, with M = Li, Na, K, and Rb, using density functional theory (DFT) at the BP86/TZ2P level. Our objective is to determine how the structure and thermochemistry (e.g., H-M bond lengths and strengths, oligomerization energies, etc.) of alkali metal hydrides depend on the metal atom, and to understand the emerging trends in terms of quantitative Kohn-Sham molecular orbital (KS-MO) theory. The H-M bond becomes longer and weaker, both in the monomers and tetramers, if one descends the periodic table from Li to Rb. Quantitative bonding analyses show that this trend is not determined by decreasing electrostatic attraction but, primarily, by the weakening in orbital interactions. The latter become less stabilizing along Li-Rb because the bond overlap between the singly occupied molecular orbitals (SOMOs) of H* and M* radicals decreases as the metal ns atomic orbital (AO) becomes larger and more diffuse. Thus, the H-M bond behaves as a text-book electron-pair bond and, in that respect, it is covalent, despite a high polarity. For the lithium and sodium hydride tetramers, the H4 tetrahedron is larger than and surrounds the M4 cluster (i.e., H-H > M-M). Interestingly, this is no longer the case in the potassium and rubidium hydride tetramers, in which the H4 tetrahedron is smaller than and inside the M4 cluster (i.e., H-H < M-M). PMID:17328442

  4. New class of scorpionate: tris(tetrazolyl)-iron complex and its different coordination modes for alkali metal ions.

    PubMed

    Park, Ka Hyun; Lee, Kang Mun; Go, Min Jeong; Choi, Sung Ho; Park, Hyoung-Ryun; Kim, Youngjo; Lee, Junseong

    2014-08-18

    We report formation of a new metallascorpionate ligand, [FeL3](3-) (IPtz), containing a Fe core and three 5-(2-hydroxyphenyl)-1H-tetrazole (LH2) ligands. It features two different binding sites, oxygen and nitrogen triangles, which consist of three oxygen or nitrogen donors from tetrazole. The binding affinities of the complex for three alkali metal ions were studied using UV spectrophotometry titrations. All three alkali metal ions show high affinities and binding constants (>3 × 10(6) M(-1)), based on the 1:1 binding isotherms to IPtz. The coordination modes of the alkali metals and IPtz in the solid were studied using X-ray crystallography; two different electron-donor sites show different coordination numbers for Li(+), Na(+), and K(+) ions. The oxygen triangles have the κ(2) coordination mode with Li(+) and κ(3) coordination mode with Na(+) and K(+) ions, whereas the nitrogen triangles show κ(3) coordination with K(+) only. The different binding affinities of IPtz in the solid were manipulated using multiple metal precursors. A Fe-K-Zn trimetallic complex was constructed by assembly of an IPtz ligand, K, and Zn precursors and characterized using X-ray crystallography. Oxygen donors are coordinated with the K ion via the κ(3) coordination mode, and nitrogen donors are coordinated with Zn metal by κ(3) coordination. The solid-state structure was confirmed to be a honeycomb coordination polymer with a one-dimensional infinite metallic array, i.e., -(K-K-Fe-Zn-Fe-K)n-.

  5. Microfluidic platforms for gallium-based liquid metal alloy

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung

    As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non

  6. Development and fabrication of high strength alloy fibers for use in metal-metal matrix composites

    NASA Technical Reports Server (NTRS)

    King, G. W.; Petrasek, D. W.

    1979-01-01

    Metal fiber reinforced superalloys are being considered for construction of critical components in turbine engines that operate at high temperature. The problems involved in fabricating refractory metal alloys into wire form in such a manner as to maximize their strength properties without developing excessive structural defects are described. The fundamental principles underlying the development of such alloy fibers are also briefly discussed. The progress made to date in developing tungsten, tantalum and columbium base alloys for fiber reinforcement is reported and future prospects for alloy fiber development considered.

  7. 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.

  8. Elastic properties of Pu metal and Pu-Ga alloys

    SciTech Connect

    Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

    2010-01-05

    We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

  9. Fine tuning of graphene-metal adhesion by surface alloying.

    PubMed

    Alfè, D; Pozzo, M; Miniussi, E; Günther, S; Lacovig, P; Lizzit, S; Larciprete, R; Santos Burgos, B; Menteş, T O; Locatelli, A; Baraldi, A

    2013-01-01

    We show that bimetallic surface alloying provides a viable route for governing the interaction between graphene and metal through the selective choice of the elemental composition of the surface alloy. This concept is illustrated by an experimental and theoretical characterization of the properties of graphene on a model PtRu surface alloy on Ru(0001), with a concentration of Pt atoms in the first layer between 0 and 50%. The progressive increase of the Pt content determines the gradual detachment of graphene from the substrate, which results from the modification of the carbon orbital hybridization promoted by Pt. Alloying is also found to affect the morphology of graphene, which is strongly corrugated on bare Ru, but becomes flat at a Pt coverage of 50%. The method here proposed can be readily extended to several supports, thus opening the way to the conformal growth of graphene on metals and to a full tunability of the graphene-substrate interaction. PMID:23938361

  10. A simple approach to metal hydride alloy optimization

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Miller, C.; Landel, R. F.

    1976-01-01

    Certain metals and related alloys can combine with hydrogen in a reversible fashion, so that on being heated, they release a portion of the gas. Such materials may find application in the large scale storage of hydrogen. Metal and alloys which show high dissociation pressure at low temperatures, and low endothermic heat of dissociation, and are therefore desirable for hydrogen storage, give values of the Hildebrand-Scott solubility parameter that lie between 100-118 Hildebrands, (Ref. 1), close to that of dissociated hydrogen. All of the less practical storage systems give much lower values of the solubility parameter. By using the Hildebrand solubility parameter as a criterion, and applying the mixing rule to combinations of known alloys and solid solutions, correlations are made to optimize alloy compositions and maximize hydrogen storage capacity.

  11. Stability of ferromagnetism against doping in half-metallic alloys

    NASA Astrophysics Data System (ADS)

    Galanakis, I.; Şaşıoǧlu, E.

    2011-06-01

    We use a rigid band model to simulate doping in half-metallic NiMnSb and CoMnSb semi-Heusler alloys. Using first-principles calculations we calculate the intrasublattice exchange constants and the Curie temperature for these alloys as a function of the shift of the Fermi level and compare them also with the case of half-metallic CrAs and CrSe zinc-blende alloys. We show for all four compounds that the interactions between Cr-Cr(Mn-Mn) nearest neighbors are sufficient to explain the behavior of the Curie temperature. The interplay between the ferromagnetic RKKY-like and the antiferromagnetic superexchange interactions depends strongly on the details of the density of states around the minority-spin gap and thus it is found to be alloy-dependent.

  12. Elastic properties of Pu metal and Pu-Ga alloys

    NASA Astrophysics Data System (ADS)

    Söderlind, Per; Landa, Alex; Klepeis, J. E.; Suzuki, Y.; Migliori, A.

    2010-06-01

    We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga (δ) alloys together with ab initio equilibrium equation of state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from α→β→γ plutonium, thus suggesting increasing f -electron correlation and a corresponding softening of the elastic moduli. For the δ-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants imply a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

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

    PubMed

    Tretiak, O Yu; Blanchard, J W; Budker, D; Olshin, P K; Smirnov, S N; Balabas, M V

    2016-03-01

    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-resonance 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. PMID:26957176

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

    NASA Astrophysics Data System (ADS)

    Tretiak, O. Yu.; Blanchard, J. W.; Budker, D.; Olshin, P. K.; Smirnov, S. N.; Balabas, M. V.

    2016-03-01

    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-resonance 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.

  15. Plasma assisted spectroscopic monitoring of alkali metals in pressurised combustion and gasification

    SciTech Connect

    Haeyrinen, V.T.; Hernberg, R.G.

    1995-07-01

    The paper describes an instrument for on-line concentration measurement of vaporised alkali compounds in pressurised industrial combustion and gasification processes. The measurement is based on Plasma Excited Alkali Resonance Line Spectroscopy (PEARLS) at the elevated pressure (1-3 MPa) of the process. Results are presented from laboratory calibration measurements and test measurements of sodium and potassium vapours resulting from the combustion of coal powder in a pressurised entrained flow reactor.

  16. Cleavage crystallography of liquid metal embrittled aluminum alloys

    NASA Technical Reports Server (NTRS)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  17. Graded coatings for metallic implant alloys

    SciTech Connect

    Saiz, Eduardo; Tomsia, Antoni P.; Fujino, Shigeru; Gomez-Vega, Jose M.

    2002-08-01

    Graded glass and glass-hydroxyapatite coatings on Ti-based and Co-Cr alloys have been prepared using a simple enameling technique. The composition of the glasses has been tailored to match the thermal expansion of the alloys. By controlling the firing time, and temperature, it has been possible to control the reactivity between the glass and the alloy and to fabricate coatings (25 to 150 mu m thick) with excellent adhesion to the substrate, resistant to corrosion and able to precipitate hydroxyapatite during in vitro tests in simulated body fluid.

  18. 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.

  19. 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.

  20. The energetics of ordered intermetallic alloys (of the transition metals)

    SciTech Connect

    Watson, R.E.; Weinert, M.; Davenport, J.W. ); Fernando, G.W. . Dept. of Physics); Bennett, L.H. . Metallurgy Div.)

    1992-01-01

    The atomically ordered phases in ordered transition metal alloys are discussed. This chapter is divided into: physical parameters controlling phase stability (Hume-Rothery, structural maps, Miedema Hamiltonian), wave functions band theory, comment on entropy terms, cohesive energies (electron promotion energies, Hund's rule on orbital effects), structural energies/stabilities of elemental solids, total energies and atomic positions, charge transfer (Au alloys, charge tailing), heats of formation of ordered compounds.

  1. The energetics of ordered intermetallic alloys (of the transition metals)

    SciTech Connect

    Watson, R.E.; Weinert, M.; Davenport, J.W.; Fernando, G.W.; Bennett, L.H.

    1992-10-01

    The atomically ordered phases in ordered transition metal alloys are discussed. This chapter is divided into: physical parameters controlling phase stability (Hume-Rothery, structural maps, Miedema Hamiltonian), wave functions & band theory, comment on entropy terms, cohesive energies (electron promotion energies, Hund`s rule on orbital effects), structural energies/stabilities of elemental solids, total energies and atomic positions, charge transfer (Au alloys, charge tailing), heats of formation of ordered compounds.

  2. Selectivity and permeation in calcium release channel of cardiac muscle: alkali metal ions.

    PubMed Central

    Chen, D P; Xu, L; Tripathy, A; Meissner, G; Eisenberg, B

    1999-01-01

    Current was measured from single open channels of the calcium release channel (CRC) of cardiac sarcoplasmic reticulum (over the range +/-180 mV) in pure and mixed solutions (e.g., biionic conditions) of the alkali metal ions Li+, K+, Na+, Rb+, Cs+, ranging in concentration from 25 mM to 2 M. The current-voltage (I-V) relations were analyzed by an extension of the Poisson-Nernst-Planck (PNP) formulation of electrodiffusion, which includes local chemical interaction described by an offset in chemical potential, which likely reflects the difference in dehydration/solvation/rehydration energies in the entry/exit steps of permeation. The theory fits all of the data with few adjustable parameters: the diffusion coefficient of each ion species, the average effective charge distribution on the wall of the pore, and an offset in chemical potential for lithium and sodium ions. In particular, the theory explains the discrepancy between "selectivities" defined by conductance sequence and "selectivities" determined by the permeability ratios (i.e., reversal potentials) in biionic conditions. The extended PNP formulation seems to offer a successful combined treatment of selectivity and permeation. Conductance selectivity in this channel arises mostly from friction: different species of ions have different diffusion coefficients in the channel. Permeability selectivity of an ion is determined by its electrochemical potential gradient and local chemical interaction with the channel. Neither selectivity (in CRC) seems to involve different electrostatic interaction of different ions with the channel protein, even though the ions have widely varying diameters. PMID:10049318

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  4. New Alloy for Glass-to-Metal Seals

    NASA Technical Reports Server (NTRS)

    Schmuck, A. J.

    1986-01-01

    Coefficient of thermal expansion approximates that of glass more closely. Alloy composed of about 60 percent iron, 40 percent nickel, and traces of six other elements. Developed as replacement for Kovar Fe/Ni/Co alloy in ferrule-and-tube assembly, new alloy has same strength, solderability, and compatibility with fuel as does Kovar. Used in glass-to-metal seals without excessive residual stresses. Potential for other applications in which low thermal expansion important; mechanical measuring devices and precise sliding parts that must function over wide temperature ranges.

  5. Quantum Chemistry for Surface Segregation in Metal Alloys

    SciTech Connect

    Sholl, David

    2006-08-31

    Metal alloys are vital materials for the fabrication of high-flux, high-selectivity hydrogen separation membranes. A phenomenon that occurs in alloys that does not arise in pure metals is surface segregation, where the composition of the surface differs from the bulk composition. Little is known about the strength of surface segregation in the alloys usually considered for hydrogen membranes. Despite this lack of knowledge, surface segregation may play a decisive role in the ability of appropriately chosen alloys to be resistant to chemical poisoning, since membrane poisoning is controlled by surface chemistry. The aim of this Phase I project is to develop quantum chemistry approaches to assess surface segregation in a prototypical hydrogen membrane alloy, fcc Pd{sub 75}Cu{sub 25}. This alloy is known experimentally to have favorable surface properties as a poison resistant H{sub 2} purification membrane (Kamakoti et al., Science 307 (2005) 569-573), but previous efforts at modeling surfaces of this alloy have ignored the possible role of surface segregation (Alfonso et al., Surf. Sci. 546 (2003) 12-26).

  6. Room temperature creep in metals and alloys

    SciTech Connect

    Deibler, Lisa Anne

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  7. Developing gradient metal alloys through radial deposition additive manufacturing.

    PubMed

    Hofmann, Douglas C; Roberts, Scott; Otis, Richard; Kolodziejska, Joanna; Dillon, R Peter; Suh, Jong-ook; Shapiro, Andrew A; Liu, Zi-Kui; Borgonia, John-Paul

    2014-01-01

    Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to alter their mechanical and physical properties. Using the technique in combination with rotational deposition enables fabrication of compositional gradients radially from the center of a sample. A roadmap for developing gradient alloys is presented that uses multi-component phase diagrams as maps for composition selection so as to avoid unwanted phases. Practical applications for the new technology are demonstrated in low-coefficient of thermal expansion radially graded metal inserts for carbon-fiber spacecraft panels.

  8. Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing

    PubMed Central

    Hofmann, Douglas C.; Roberts, Scott; Otis, Richard; Kolodziejska, Joanna; Dillon, R. Peter; Suh, Jong-ook; Shapiro, Andrew A.; Liu, Zi-Kui; Borgonia, John-Paul

    2014-01-01

    Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to alter their mechanical and physical properties. Using the technique in combination with rotational deposition enables fabrication of compositional gradients radially from the center of a sample. A roadmap for developing gradient alloys is presented that uses multi-component phase diagrams as maps for composition selection so as to avoid unwanted phases. Practical applications for the new technology are demonstrated in low-coefficient of thermal expansion radially graded metal inserts for carbon-fiber spacecraft panels. PMID:24942329

  9. Method for low temperature preparation of a noble metal alloy

    DOEpatents

    Even, Jr., William R.

    2002-01-01

    A method for producing fine, essentially contamination free, noble metal alloys is disclosed. The alloys comprise particles in a size range of 5 to 500 nm. The method comprises 1. A method for preparing a noble metal alloy at low temperature, the method comprising the steps of forming solution of organometallic compounds by dissolving the compounds into a quantity of a compatible solvent medium capable of solvating the organometallic, mixing a portion of each solution to provide a desired molarity ratio of ions in the mixed solution, adding a support material, rapidly quenching droplets of the mixed solution to initiate a solute-solvent phase separation as the solvent freezes, removing said liquid cryogen, collecting and freezing drying the frozen droplets to produce a dry powder, and finally reducing the powder to a metal by flowing dry hydrogen over the powder while warming the powder to a temperature of about 150.degree. C.

  10. Development of new metallic alloys for biomedical applications.

    PubMed

    Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko

    2012-11-01

    New low modulus β-type titanium alloys for biomedical applications are still currently being developed. Strong and enduring β-type titanium alloy with a low Young's modulus are being investigated. A low modulus has been proved to be effective in inhibiting bone atrophy, leading to good bone remodeling in a bone fracture model in the rabbit tibia. Very recently β-type titanium alloys with a self-tunable modulus have been proposed for the construction of removable implants. Nickel-free low modulus β-type titanium alloys showing shape memory and super elastic behavior are also currently being developed. Nickel-free stainless steel and cobalt-chromium alloys for biomedical applications are receiving attention as well. Newly developed zirconium-based alloys for biomedical applications are proving very interesting. Magnesium-based or iron-based biodegradable biomaterials are under development. Further, tantalum, and niobium and its alloys are being investigated for biomedical applications. The development of new metallic alloys for biomedical applications is described in this paper. PMID:22765961

  11. Development of new metallic alloys for biomedical applications.

    PubMed

    Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko

    2012-11-01

    New low modulus β-type titanium alloys for biomedical applications are still currently being developed. Strong and enduring β-type titanium alloy with a low Young's modulus are being investigated. A low modulus has been proved to be effective in inhibiting bone atrophy, leading to good bone remodeling in a bone fracture model in the rabbit tibia. Very recently β-type titanium alloys with a self-tunable modulus have been proposed for the construction of removable implants. Nickel-free low modulus β-type titanium alloys showing shape memory and super elastic behavior are also currently being developed. Nickel-free stainless steel and cobalt-chromium alloys for biomedical applications are receiving attention as well. Newly developed zirconium-based alloys for biomedical applications are proving very interesting. Magnesium-based or iron-based biodegradable biomaterials are under development. Further, tantalum, and niobium and its alloys are being investigated for biomedical applications. The development of new metallic alloys for biomedical applications is described in this paper.

  12. Tandem mass spectrometric study of ciprofloxacin-poly(ethylene glycol) conjugate in the presence of alkali metal ions

    NASA Astrophysics Data System (ADS)

    Kéki, Sándor; Nagy, Lajos; Kuki, Ákos; Pintér, Gábor; Herczegh, Pál; Zsuga, Miklós

    2008-08-01

    The fragmentation and fragmentation behaviors of singly, doubly, and triply charged adducts of ciprofloxacin-poly(ethylene glycol) conjugate (P_Cf) with alkali metal ions, including Li+, Na+ and K+ ions, generated by electrospray (ESI) were studied as a function of collision energy. The product ion spectra of adducts with charge states +1, +2, and +3 are dominated by product ions arising from the loss-neutral moiety (ciprofloxacin) and CO2, and ions formed by dissociation of the precursor ion ([P_Cf + xM]x+) into product ions [P + (x - 1)M](x-1)+ and [Cf + M]+ (where P_Cf, P and Cf represent the ciprofloxacin-poly(ethylene glycol) conjugate, the poly(ethylene glycol) backbone without the endgroups, and the ciprofloxacin moiety, respectively; M is the alkali metal ion and x is the charge). It was found that the metal ions do not significantly alter the fragmentation pattern of ciprofloxacin-poly(ethylene glycol) conjugate. It is also interesting that the run and the shape of the survival yield curves for the singly and doubly charged adduct ions are independent of the cation. However, in the case of triply charged adducts, survival yield curves follow each other in the order K+, Na+, and Li+. Based on the experimental results, a fragmentation mechanism for the singly and multiply charged adducts of P_Cf with alkali metal ions is given. In addition, a tentative description of the signal intensity variations of the product ions with the lab frame collision energy is also reported.

  13. How alkali metal ion binding alters the conformation preferences of gramicidin A: a molecular dynamics and ion mobility study.

    PubMed

    Chen, Liuxi; Gao, Yi Qin; Russell, David H

    2012-01-12

    Here, we present a systematic study combing electrospray ionization-ion mobility experiments and an enhanced sampling molecular dynamics, specifically integrated tempering sampling molecular dynamics simulations (ITS-MDS), to explore the conformations of alkali metal ion (Na, K, and Cs) adducts of gramicidin A (GA) in vacuo. Folding simulation is performed to obtain inherent conformational preferences of neutral GA to provide insights about how the binding of metal ions influences the intrinsic conformations of GA. The comparison between conformations of neutral GA and alkali metal ion adducts reveals a high degree of structural similarity, especially between neutral GA and [GA + Na](+); however, the structural similarities decrease as ionic radius of the metal increases. Collision cross section (CCS) profiles for [GA + Na](+) and [GA + Cs](+) ions obtained from by ITS-MDS compare favorably with the experimental CCS, but there are significant differences from CCS profiles for [GA + K](+) ions. Such discrepancies between the calculated and measured CCS profiles for [GA + K](+) are discussed in terms of limitations in the simulation force field as well as possible size-dependent coordination of the [GA + K](+) ion complex.

  14. Electromagnetic Characterization Of Metallic Sensory Alloy

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Simpson, John; Wallace, Terryl A.; Newman, John A.; Leser, Paul; Lahue, Rob

    2012-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  15. Processing of Refractory Metal Alloys for JOYO Irradiations

    SciTech Connect

    RF Luther; ME Petrichek

    2006-02-21

    This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang.

  16. Ancient Metal Mirror Alloy Revisited: Quasicrystalline Nanoparticles Observed

    NASA Astrophysics Data System (ADS)

    Sekhar, J. A.; Mantri, A. S.; Yamjala, S.; Saha, Sabyasachi; Balamuralikrishnan, R.; Rao, P. Rama

    2015-12-01

    This article presents, for the first time, evidence of nanocrystalline structure, through direct transmission electron microscopy (TEM) observations, in a Cu-32 wt.% Sn alloy that has been made by an age-old, uniquely crafted casting process. This alloy has been used as a metal mirror for centuries. The TEM images also reveal five-sided projections of nano-particles. The convergent beam nano-diffraction patterns obtained from the nano-particles point to the nano-phase being quasicrystalline, a feature that has never before been reported for a copper alloy, although there have been reports of the presence of icosahedral `clusters' within large unit cell intermetallic phases. This observation has been substantiated by x-ray diffraction, wherein the observed peaks could be indexed to an icosahedral quasi-crystalline phase. The mirror alloy casting has been valued for its high hardness and high reflectance properties, both of which result from its unique internal microstructure that include nano-grains as well as quasi-crystallinity. We further postulate that this microstructure is a consequence of the raw materials used and the manufacturing process, including the choice of mold material. While the alloy consists primarily of copper and tin, impurity elements such as zinc, iron, sulfur, aluminum and nickel are also present, in individual amounts not exceeding one wt.%. It is believed that these trace impurities could have influenced the microstructure and, consequently, the properties of the metal mirror alloy.

  17. 49 CFR 173.187 - Pyrophoric solids, metals or alloys, n.o.s.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Pyrophoric solids, metals or alloys, n.o.s. 173... Class 1 and Class 7 § 173.187 Pyrophoric solids, metals or alloys, n.o.s. Packagings for pyrophoric solids, metals, or alloys, n.o.s. must conform to the requirements of part 178 of this subchapter at...

  18. Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking

    DOEpatents

    Steeves, Arthur F.; Stewart, James C.

    1981-01-01

    A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

  19. Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking

    DOEpatents

    Not Available

    1980-05-28

    A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking is described. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

  20. Potential Modulated Intercalation of Alkali Cations into Metal Hexacyanoferrate Coated Electrodes

    SciTech Connect

    Daniel T. Schwartz; Bekki Liu; Marlina Lukman; Kavita M. Jeerage; William A. Steen; Haixia Dai; Qiuming Yu; J. Antonio Medina

    2002-02-18

    Nickel hexacyanoferrate is a polynuclear inorganic ion intercalation material that loads (intercalates) and elutes (deintercalates) alkali cations from its structure when electrochemically reduced and oxidized, respectively. Nickel hexacyanoferrrate (NiHCF) is known to preferentially intercalate cesium over all other alkali cations, thus providing a basis for a separation scheme that can tackle DOE's radiocesium contamination problem. This program studied fundamental issues in alkalization intercalation and deintercalation in nickel hexacyanoferrate compounds, with the goal of (1) quantifying the ion exchange selectivity properties from cation mixtures, (2) enhancing ion exchange capacities, and (3) and understanding the electrochemically-switched ion exchange process (ESIX).

  1. 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

    2016-06-01

    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.

  2. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, J.E.; Kelly, T.F.

    1999-06-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains. 20 figs.

  3. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, John E.; Kelly, Thomas F.

    1999-01-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

  4. High temperature seal for joining ceramics and metal alloys

    DOEpatents

    Maiya, P. Subraya; Picciolo, John J.; Emerson, James E.; Dusek, Joseph T.; Balachandran, Uthamalingam

    1998-01-01

    For a combination of a membrane of SrFeCo.sub.0.5 O.sub.x and an Inconel alloy, a high-temperature seal is formed between the membrane and the alloy. The seal is interposed between the alloy and the membrane, and is a fritted compound of Sr oxide and boric oxide and a fritted compound of Sr, Fe and Co oxides. The fritted compound of SrFeCo.sub.0.50 O.sub.x is present in the range of from about 30 to 70 percent by weight of the total sealant material and the fritted compound of Sr oxide and boric oxide has a mole ratio of 2 moles of the Sr oxide for each mole of boric oxide. A method of sealing a ceramic to an Inconel metal alloy is also disclosed.

  5. High temperature seal for joining ceramics and metal alloys

    DOEpatents

    Maiya, P.S.; Picciolo, J.J.; Emerson, J.E.; Dusek, J.T.; Balachandran, U.

    1998-03-10

    For a combination of a membrane of SrFeCo{sub 0.5}O{sub x} and an Inconel alloy, a high-temperature seal is formed between the membrane and the alloy. The seal is interposed between the alloy and the membrane, and is a fritted compound of Sr oxide and boric oxide and a fritted compound of Sr, Fe and Co oxides. The fritted compound of SrFeCo{sub 0.50}O{sub x} is present in the range of from about 30 to 70 percent by weight of the total sealant material and the fritted compound of Sr oxide and boric oxide has a mole ratio of 2 moles of the Sr oxide for each mole of boric oxide. A method of sealing a ceramic to an Inconel metal alloy is also disclosed. 3 figs.

  6. Molybdenum-A Key Component of Metal Alloys

    USGS Publications Warehouse

    Kropschot, S.J.

    2010-01-01

    Molybdenum, whose chemical symbol is Mo, was first recognized as an element in 1778. Until that time, the mineral molybdenite-the most important source of molybdenum-was believed to be a lead mineral because of its metallic gray color, greasy feel, and softness. In the late 19th century, French metallurgists discovered that molybdenum, when alloyed (mixed) with steel in small quantities, creates a substance that is remarkably tougher than steel alone and is highly resistant to heat. The alloy was found to be ideal for making tools and armor plate. Today, the most common use of molybdenum is as an alloying agent in stainless steel, alloy steels, and superalloys to enhance hardness, strength, and resistance to corrosion.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  8. Alkali metal salts of rutin - Synthesis, spectroscopic (FT-IR, FT-Raman, UV-VIS), antioxidant and antimicrobial studies.

    PubMed

    Samsonowicz, M; Kamińska, I; Kalinowska, M; Lewandowski, W

    2015-12-01

    In this work several metal salts of rutin with lithium, sodium, potassium, rubidium and cesium were synthesized. Their molecular structures were discussed on the basis of spectroscopic (FT-IR, FT-Raman, UV-VIS) studies. Optimized geometrical structure of rutin was calculated by B3LYP/6-311++G(∗∗) method and sodium salt of rutin were calculated by B3LYP/LanL2DZ method. Metal chelation change the biological properties of ligand therefore the antioxidant (FRAP and DPPH) and antimicrobial activities (toward Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida albicans and Saccharomyces cerevisiae) of alkali metal salts were evaluated and compared with the biological properties of rutin. PMID:26184478

  9. Formation and Reduction of Pollutants in CFBC: From Heavy Metals, Particulates, Alkali, NOx, N2O, SOx, HCl

    NASA Astrophysics Data System (ADS)

    Winter, Franz

    Due to the advantages of fluidized bed combustors a wide range of different fuels is utilized. The fuels range from anthracite, medium and low rank coals to peat, wood residues, biomass waste, sewage sludge and other sludges to plastics and municipal solid waste. Because of this wide range of fuels pollutants such as heavy metals, particulates, alkali, NO, NO2, N2O, SO2, SO3 and HCI may be formed during the fuel conversion process depending on the fuel and operating conditions.

  10. Sensitive determination of the spin polarization of optically pumped alkali-metal atoms using near-resonant light

    PubMed Central

    Ding, Zhichao; Long, Xingwu; Yuan, Jie; Fan, Zhenfang; Luo, Hui

    2016-01-01

    A new method to measure the spin polarization of optically pumped alkali-metal atoms is demonstrated. Unlike the conventional method using far-detuned probe light, the near-resonant light with two specific frequencies was chosen. Because the Faraday rotation angle of this approach can be two orders of magnitude greater than that with the conventional method, this approach is more sensitive to the spin polarization. Based on the results of the experimental scheme, the spin polarization measurements are found to be in good agreement with the theoretical predictions, thereby demonstrating the feasibility of this approach. PMID:27595707

  11. Structure of the alkali-metal-atom + strontium molecular ions: Towards photoassociation and formation of cold molecular ions

    SciTech Connect

    Aymar, M.; Dulieu, O.; Guerout, R.

    2011-08-14

    The potential energy curves, permanent and transition dipole moments, and the static dipolar polarizability, of molecular ions composed of one alkali-metal atom and a strontium ion are determined with a quantum chemistry approach. The molecular ions are treated as effective two-electron systems and are treated using effective core potentials including core polarization, large gaussian basis sets, and full configuration interaction. In the perspective of upcoming experiments aiming at merging cold atom and cold ion traps, possible paths for radiative charge exchange, photoassociation of a cold lithium or rubidium atom and a strontium ion are discussed, as well as the formation of stable molecular ions.

  12. Sensitive determination of the spin polarization of optically pumped alkali-metal atoms using near-resonant light.

    PubMed

    Ding, Zhichao; Long, Xingwu; Yuan, Jie; Fan, Zhenfang; Luo, Hui

    2016-01-01

    A new method to measure the spin polarization of optically pumped alkali-metal atoms is demonstrated. Unlike the conventional method using far-detuned probe light, the near-resonant light with two specific frequencies was chosen. Because the Faraday rotation angle of this approach can be two orders of magnitude greater than that with the conventional method, this approach is more sensitive to the spin polarization. Based on the results of the experimental scheme, the spin polarization measurements are found to be in good agreement with the theoretical predictions, thereby demonstrating the feasibility of this approach. PMID:27595707

  13. Metal Alloy Compositions And Process Background Of The Invention

    DOEpatents

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  14. Alloying of metals for corrosion resistance

    SciTech Connect

    McCafferty, E.; Hubler, G.K.; Natishan, P.M.

    1989-09-29

    The corrosion resistance of bulk metals is improved by implanting a corrosion-resistant species into the surface of the bulk metal in a layer beginning at the surface and extending to a depth of at least about 50 angstroms. An amount of corrosion-resistant species is deposited so that the oxide layer that forms on the corrosion-resistant species implanted bulk metal is composed of at least about three percent of the oxide of the corrosion-resistant species.

  15. Transition rates for lithium-like ions, sodium-like ions, and neutral alkali-metal atoms

    SciTech Connect

    Johnson, W.R.; Liu, Z.W.; Sapirstein, J.

    1996-11-01

    Third-order many-body perturbation theory is used to obtain E1 transition amplitudes for ions of the lithium and sodium isoelectronic sequences and for the neutral alkali-metal atoms potassium, rubidium, cesium, and francium. Complete angular reductions of the first, second, and third-order amplitudes are given. Tables of transition energies and rates are given for the 2p{sub {1/2}} {yields} 2s{sub {1/2}}, 2p{sub 3/2} {yields} 2s{sub {1/2}}, 3s{sub {1/2}} {yields} 2p{sub {1/2}}, and 3s{sub {1/2}} {yields} 2p{sub 3/2} transitions in the lithium isoelectronic sequence and for the corresponding 3p{sub 1/2} {yields} 3s{sub 1/2}, 3p{sub 3/2} {yields} 3s{sub {1/2}}, 4s{sub {1/2}} {yields} 3p{sub 1/2}, and 4s{sub {1/2}} {yields} 3p{sub 3/2} transitions in the sodium sequence. For neutral alkali atoms, amplitudes of np{sub {1/2}} {yields} ns{sub {1/2}}, np{sub 3/2} {yields} ns{sub {1/2}}, (n + 1)s{sub {1/2}} {yields} np{sub {1/2}}, and (n + 1)s{sub {1/2}} {yields} np{sub 3/2} transitions are evaluated, where n is the principal quantum number of the valence electron in the atomic ground state, Semi-empirical corrections for the omitted fourth- and higher-order terms in perturbation theory are given for the neutral alkali-metal atoms. Comparisons with previous high-precision calculations and with experiment are made. 42 refs., 1 fig., 12 tabs.

  16. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    DOEpatents

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  17. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

    1995-01-01

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

  18. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

    1995-06-06

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

  19. Superior metallic alloys through rapid solidification processing (RSP) by design

    SciTech Connect

    Flinn, J.E.

    1995-05-01

    Rapid solidification processing using powder atomization methods and the control of minor elements such as oxygen, nitrogen, and carbon can provide metallic alloys with superior properties and performance compared to conventionally processing alloys. Previous studies on nickel- and iron-base superalloys have provided the baseline information to properly couple RSP with alloy composition, and, therefore, enable alloys to be designed for performance improvements. The RSP approach produces powders, which need to be consolidated into suitable monolithic forms. This normally involves canning, consolidation, and decanning of the powders. Canning/decanning is expensive and raises the fabrication cost significantly above that of conventional, ingot metallurgy production methods. The cost differential can be offset by the superior performance of the RSP metallic alloys. However, without the performance database, it is difficult to convince potential users to adopt the RSP approach. Spray casting of the atomized molten droplets into suitable preforms for subsequent fabrication can be cost competitive with conventional processing. If the fine and stable microstructural features observed for the RSP approach are preserved during spray casing, a cost competitive product can be obtained that has superior properties and performance that cannot be obtained by conventional methods.

  20. Study of complexation between two 1,3-alternate calix[4]crown derivatives and alkali metal ions by electrospray ionization mass spectrometry and density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Shamsipur, Mojtaba; Allahyari, Leila; Fasihi, Javad; Taherpour, Avat (Arman); Asfari, Zuhair; Valinejad, Azizollah

    2016-03-01

    Complexation of two 1,3-alternate calix[4]crown ligands with alkali metals (K+, Rb+ and Cs+) has been investigated by electrospray ionization mass spectrometry (ESI-MS) and density functional theory calculations. The binding selectivities of the ligands and the binding constants of their complexes in solution have been determined using the obtained mass spectra. Also the percentage of each formed complex species in the mixture of each ligand and alkali metal has been experimentally evaluated. For both calix[4]crown-5 and calix[4]crown-6 ligands the experimental and theoretical selectivity of their alkali metal complexes found to follow the trend K+ > Rb+ > Cs+. The structures of ligands were optimized by DFT-B3LYP/6-31G method and the structures of complexes were obtained by QM-SCF-MO/PM6 method and discussed in the text.

  1. Method for locating metallic nitride inclusions in metallic alloy ingots

    SciTech Connect

    White, Jack C.; Traut, Davis E.; Oden, Laurance L.; Schmitt, Roman A.

    1992-01-01

    A method of determining the location and history of metallic nitride and/or oxynitride inclusions in metallic melts. The method includes the steps of labeling metallic nitride and/or oxynitride inclusions by making a coreduced metallic-hafnium sponge from a mixture of hafnium chloride and the chloride of a metal, reducing the mixed chlorides with magnesium, nitriding the hafnium-labeled metallic-hafnium sponge, and seeding the sponge to be melted with hafnium-labeled nitride inclusions. The ingots are neutron activated and the hafnium is located by radiometric means. Hafnium possesses exactly the proper metallurgical and radiochemical properties for this use.

  2. Study on electrical properties of metal/GaSb junctions using metal-GaSb alloys

    SciTech Connect

    Nishi, Koichi Yokoyama, Masafumi; Kim, Sanghyeon; Takenaka, Mitsuru; Takagi, Shinichi; Yokoyama, Haruki

    2014-01-21

    We study the metal-GaSb alloy formation, the structural properties and the electrical characteristics of the metal-alloy/GaSb diodes by employing metal materials such as Ni, Pd, Co, Ti, Al, and Ta, in order to clarify metals suitable for GaSb p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) as metal-GaSb alloy source/drain (S/D). It is found that Ni, Pd, Co, and Ti can form alloy with GaSb by rapid thermal annealing at 250, 250, 350, and 450 °C, respectively. The Ni-GaSb and Pd-GaSb alloy formation temperature of 250 °C is lower than the conventional dopant activation annealing for ion implantation, which enable us to lower the process temperature. The alloy layers show lower sheet resistance (R{sub Sheet}) than that of p{sup +}-GaSb layer formed by ion implantation and activation annealing. We also study the electrical characteristics of the metal-alloy/GaSb junctions. The alloy/n-GaSb contact has large Schottky barrier height (ϕ{sub B}) for electrons, ∼0.6 eV, and low ϕ{sub B} for holes, ∼0.2 eV, which enable us to realize high on/off ratio in pMOSFETs. We have found that the Ni-GaSb/GaSb Schottky junction shows the best electrical characteristics with ideal factor (n) of 1.1 and on-current/off-current ratio (I{sub on}/I{sub off}) of ∼10{sup 4} among the metal-GaSb alloy/GaSb junctions evaluated in the present study. These electrical properties are also superior to those of a p{sup +}-n diode fabricated by Be ion implantation with activation annealing at 350 °C. As a result, the Ni-GaSb alloy can be regarded as one of the best materials to realize metal S/D in GaSb pMOSFETs.

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

    PubMed

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

    2015-05-20

    The main theme of this work is to study the influence of ion-exchangeable alkali metal cations, such as: Li(+), Na(+), K(+), and Cs(+) on the thermal, mechanical and morphological properties. In this regard, a set of rectorite/chitosan (REC-CS) bio-nanocomposite films (BNCFs) was prepared by facile reaction of chitosan with ion-exchanged REC clay. The microstructure and morphology of BNCFs were investigated with XRD, TEM, SEM and AFM. Thermal and tensile properties of BNCFs were also investigated. As revealed from TEM and XRD results, the BNCFs featured a mixed morphology. Some intercalated clay sheets, together with nano-sized clay tactoids were obtained in LiREC/CS, NaREC/CS and KREC/CS of the BNCFs. From fractured surface study, via SEM, it was observed that the dispersion of chitosan polymer attaches to (and covers) the clay platelets. FTIR confirmed strong hydrogen bonds between clay and chitosan polymer. In addition, the thermal stabilities significantly varied when alkali metal cations varied from Li(+) to Cs(+). The BNCFs featured high tensile strengths (up to 84 MPa) and tensile moduli (up to 45 GPa). After evaluating these properties of BNCFs, we came to conclusion that these bio-nano composites can be used for packaging applications. PMID:25817663

  4. 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; Bartsch, Richard A.

    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

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

    SciTech Connect

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

    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 group 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.

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

    PubMed

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

    2015-05-20

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

  7. 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. PMID:26661060

  8. XPS studies and photocurrent applications of alkali-metals-doped ZnO nanoparticles under visible illumination conditions

    NASA Astrophysics Data System (ADS)

    Saáedi, Abdolhossein; Yousefi, Ramin; Jamali-Sheini, Farid; Zak, Ali Khorsand; Cheraghizade, Mohsen; Mahmoudian, M. R.; Baghchesara, Mohammad Amin; Dezaki, Abbas Shirmardi

    2016-05-01

    The present work is a study about a relationship between X-ray photoelectron spectrometer (XPS) results and photocurrent intensity of alkali-metals-elements doped ZnO nanoparticles, which is carried out under visible illumination conditions. The nanoparticles were synthesized by a simple sol-gel method. Structure and morphology studies of the NPs were carried out by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The effect of doping on the optical band-gap was investigated by using UV-visible spectrometer. The absorption peak of the doped ZnO NPs was red-shifted with respect to that of the undoped ZnO NPs. After that, the photocurrent application of the products was examined under a white light source at 2 V bias. The photocurrent results showed that, the current intensity of the ZnO NPs was increased by doping materials. However, K-doped ZnO NPs showed the highest photocurrent intensity. Finally, a discussion was carried out about the obtained photocurrent results by the O-1s spectra of the XPS of the samples. Our results suggest that the alkali-metals-doped ZnO NPs exhibit considerable promise for highly sensitive visible-light photodetectors.

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

    PubMed

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

    2016-05-19

    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.

  10. 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.

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

    SciTech Connect

    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-(H2O), X = F, Cl, Br, I, and alkali metal-water, M+(H2O), 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 to the ab initio data that are between one and two orders of magnitude better in the χ2 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.

  12. Exchange Processes in Shibasaki's Rare Earth Alkali Metal BINOLate Frameworks and Their Relevance in Multifunctional Asymmetric Catalysis.

    PubMed

    Robinson, Jerome R; Gu, Jun; Carroll, Patrick J; Schelter, Eric J; Walsh, Patrick J

    2015-06-10

    Shibasaki's rare earth alkali metal BINOLate (REMB) catalysts (REMB; RE = Sc, Y, La - Lu; M = Li, Na, K; B = 1,1-bi-2-naphtholate; RE/M/B = 1/3/3) are among the most successful enantioselective catalysts and have been employed in a broad range of mechanistically diverse reactions. Despite the phenomenal success of these catalysts, several fundamental questions central to their reactivity remain unresolved. Combined reactivity and spectroscopic studies were undertaken to probe the identity of the active catalyst(s) in Lewis-acid (LA) and Lewis-acid/Brønsted-base (LA/BB) catalyzed reactions. Exchange spectroscopy provided a method to obtain rates of ligand and alkali metal self-exchange in the RE/Li frameworks, demonstrating the utility of this technique for probing solution dynamics of REMB catalysts. Isolation of the first crystallographically characterized REMB complex with substrate bound enabled stoichiometric and catalytic reactivity studies, wherein we observed that substrate deprotonation by the catalyst framework was necessary to achieve selectivity. Our spectroscopic observations in LA/BB catalysis are inconsistent with previous mechanistic proposals, which considered only tris(BINOLate) species as active catalysts. These findings significantly expand our understanding of the catalyst structure in these privileged multifunctional frameworks and identify new directions for development of new catalysts. PMID:25968561

  13. Effect of a metal alloy fuel catalyst on bacterial growth.

    PubMed

    Ghosh, Ruma; Koerting, Claudia; Suib, Steven L; Best, Michael H; Berlin, Alvin J

    2005-11-01

    Many microorganisms have been demonstrated to utilize petroleum fuel products to fulfill their nutritional requirement for carbon. As a result, the ability of these microbes to degrade fuel has both a deleterious affect as well as beneficial applications. This study focused on the undesired ability of bacteria to grow on fuel and the potential for some metal alloys to inhibit this biodegradation. The objective of this study was to review the pattern of growth of two reference strains of petroleum-degrading bacteria, Pseudomonas oleovorans and Rhodococcus rhodocrous, in a specific hydrocarbon environment in the presence of a commercially available alloy. The alloy formulated and supplied by Advanced Power Systems International Inc. (APSI) is sold for fuel reformulation and other purposes. The components of the alloy used in the study were antimony, tin, lead, and mercury formulated as pellets. Surface characterization also showed the presence of tin oxide and lead amalgam phases. Hydrocarbon used for the study was primarily 87-octane gasoline. The growth of the bacteria in the water and mineral-supplemented gasoline mixture over 6-8 weeks was monitored by the viable plate count method. While an initial increase in bacteria occurred in the first week, overall bacterial growth was found to be suppressed in the presence of the alloy. Results also indicate that the alloy surface characteristics that convey the catalytic activity may also contribute to the observed antibacterial activity. PMID:16262333

  14. Alloy with metallic glass and quasi-crystalline properties

    DOEpatents

    Xing, Li-Qian; Hufnagel, Todd C.; Ramesh, Kaliat T.

    2004-02-17

    An alloy is described that is capable of forming a metallic glass at moderate cooling rates and exhibits large plastic flow at ambient temperature. Preferably, the alloy has a composition of (Zr, Hf).sub.a Ta.sub.b Ti.sub.c Cu.sub.d Ni.sub.e Al.sub.f, where the composition ranges (in atomic percent) are 45.ltoreq.a.ltoreq.70, 3.ltoreq.b.ltoreq.7.5, 0.ltoreq.c.ltoreq.4, 3.ltoreq.b+c.ltoreq.10, 10.ltoreq.d.ltoreq.30, 0.ltoreq.e.ltoreq.20, 10.ltoreq.d+e.ltoreq.35, and 5.ltoreq.f.ltoreq.15. The alloy may be cast into a bulk solid with disordered atomic-scale structure, i.e., a metallic glass, by a variety of techniques including copper mold die casting and planar flow casting. The as-cast amorphous solid has good ductility while retaining all of the characteristic features of known metallic glasses, including a distinct glass transition, a supercooled liquid region, and an absence of long-range atomic order. The alloy may be used to form a composite structure including quasi-crystals embedded in an amorphous matrix. Such a composite quasi-crystalline structure has much higher mechanical strength than a crystalline structure.

  15. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, Xianghong; Peker, Atakan; Johnson, William L.

    1997-01-01

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

  16. 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.

  17. Coating with overlay metallic-cermet alloy systems

    NASA Technical Reports Server (NTRS)

    Gedwill, M. A.; Levine, S. R.; Glasgow, T. K. (Inventor)

    1984-01-01

    A base layer of an oxide dispersed, metallic alloy (cermet) is arc plasma sprayed onto a substrate, such as a turbine blade, vane, or the like, which is subjected to high temperature use. A top layer of an oxidation, hot corrosion, erosion resistant alloy of nickel, cobalt, or iron is then arc plasma sprayed onto the base layer. A heat treatment is used to improve the bonding. The base layer serves as an inhibitor to interdiffusion between the protective top layer and the substrate. Otherwise, the 10 protective top layer would rapidly interact detrimentally with the substrate and degrade by spalling of the protective oxides formed on the outer surface at elevated temperatures.

  18. Powder and particulate production of metallic alloys

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1982-01-01

    Developments of particulate metallurgy of alloyed materials where the final products is a fully dense body are discussed. Particulates are defined as powders, flakes, foils, silvers, ribbons and strip. Because rapid solidification is an important factor in particulate metallurgy, all of the particulates must have at least one dimension which is very fine, sometimes as fine as 10 to 50 microns, but move typically up to several hundred microns, provided that the dimension permits a minimum solidification rate of at least 100 K/s.

  19. Multiscale model of metal alloy oxidation at grain boundaries.

    PubMed

    Sushko, Maria L; Alexandrov, Vitaly; Schreiber, Daniel K; Rosso, Kevin M; Bruemmer, Stephen M

    2015-06-01

    High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr2O3. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl2O4. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3-10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr2O3 has a plate-like structure with 1.2-1.7 nm wide pores running along the grain boundary, while NiAl2O4 has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular direction providing an additional pathway for oxygen

  20. Multiscale model of metal alloy oxidation at grain boundaries

    SciTech Connect

    Sushko, Maria L. Alexandrov, Vitaly; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-06-07

    High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr{sub 2}O{sub 3}. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl{sub 2}O{sub 4}. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3–10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr{sub 2}O{sub 3} has a plate-like structure with 1.2–1.7 nm wide pores running along the grain boundary, while NiAl{sub 2}O{sub 4} has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular

  1. Multiscale model of metal alloy oxidation at grain boundaries

    NASA Astrophysics Data System (ADS)

    Sushko, Maria L.; Alexandrov, Vitaly; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-06-01

    High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr2O3. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl2O4. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3-10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr2O3 has a plate-like structure with 1.2-1.7 nm wide pores running along the grain boundary, while NiAl2O4 has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular direction providing an additional pathway for oxygen

  2. [Should metal alloy discs be used for patch testing in suspected metal implant intolerance reaction?].

    PubMed

    Thomas, P; Geier, J; Dickel, H; Diepgen, T; Hillen, U; Kreft, B; Schnuch, A; Szliska, C; Mahler, V

    2015-11-01

    Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, patch testing should not be done in a prophylactic-prophetic approach. Pre-implant patch testing should only be performed to verify or exclude metal allergy in patients with a reported respective history. In the case of implant-in particular arthroplasty-related complications like, for example, pain, effusion, skin changes, reduced range of motion, or loosening, orthopedic-surgical differential diagnostics should be performed first. Allergological workup of suspected metal implant allergy should be done with the DKG baseline series which contains nickel-, cobalt- and chromium-preparations. Various studies assessing the usefulness of metal alloy discs for patch testing proved that this approach does not give reliable information about metal allergy. Positive patch test reactions to the discs cannot be assigned to a specific metal within the disc alloy components. Furthermore, availability of such metal discs might be an invitation to uncritical testing. Accordingly, due to lack of benefit in comparison to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

  3. Soldering of Carbon Materials Using Transition Metal Rich Alloys.

    PubMed

    Burda, Marek; Lekawa-Raus, Agnieszka; Gruszczyk, Andrzej; Koziol, Krzysztof K K

    2015-08-25

    Joining of carbon materials via soldering has not been possible up to now due to lack of wetting of carbons by metals at standard soldering temperatures. This issue has been a severely restricting factor for many potential electrical/electronic and mechanical applications of nanostructured and conventional carbon materials. Here we demonstrate the formation of alloys that enable soldering of these structures. By addition of several percent (2.5-5%) of transition metal such as chromium or nickel to a standard lead-free soldering tin based alloy we obtained a solder that can be applied using a commercial soldering iron at typical soldering temperatures of approximately 350 °C and at ambient conditions. The use of this solder enables the formation of mechanically strong and electrically conductive joints between carbon materials and, when supported by a simple two-step technique, can successfully bond carbon structures to any metal terminal. It has been shown using optical and scanning electron microscope images as well as X-ray diffraction patterns and energy dispersive X-ray mapping that the successful formation of carbon-solder bonds is possible, first, thanks to the uniform nonreactive dispersion of transition metals in the tin-based matrix. Further, during the soldering process, these free elements diffuse into the carbon-alloy border with no formation of brazing-like carbides, which would damage the surface of the carbon materials. PMID:26256042

  4. Phase separation of metallic hydrogen-helium alloys

    NASA Technical Reports Server (NTRS)

    Straus, D. M.; Ashcroft, N. W.; Beck, H.

    1976-01-01

    Calculations are presented for the thermodynamic functions and phase separation boundaries of solid metallic hydrogen helium alloys at temperatures between 0 K and 19,000 K and at pressures between 15 and 90 megabars. Expressions for the band structure energy of a randomly disordered alloy (including third order in the electron ion interaction) are derived and evaluated. Short and long range order are included by the quasi-chemical method, and lattice dynamics in the virtual crystal harmonic approximation. We conclude that at temperatures below 4,000 K there is complete phase separation of hydrogen helium alloys, and that a miscibility gap remains at the highest temperatures and pressures considered. The relevance of these results to models of the deep interior of Jupiter is briefly discussed.

  5. PASSIVATION LAYER STABILITY OF A METALLIC ALLOY WASTE FORM

    SciTech Connect

    Williamson, M.; Mickalonis, J.; Fisher, D.; Sindelar, R.

    2010-08-16

    Alloy waste form development under the Waste Forms Campaign of the DOE-NE Fuel Cycle Research & Development program includes the process development and characterization of an alloy system to incorporate metal species from the waste streams generated during nuclear fuel recycling. This report describes the tests and results from the FY10 activities to further investigate an Fe-based waste form that uses 300-series stainless steel as the base alloy in an induction furnace melt process to incorporate the waste species from a closed nuclear fuel recycle separations scheme. This report is focused on the initial activities to investigate the formation of oxyhydroxide layer(s) that would be expected to develop on the Fe-based waste form as it corrodes under aqueous repository conditions. Corrosion tests were used to evaluate the stability of the layer(s) that can act as a passivation layer against further corrosion and would affect waste form durability in a disposal environment.

  6. Comparisons between adsorption and diffusion of alkali, alkaline earth metal atoms on silicene and those on silicane: Insight from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Bo, Xu; Huan-Sheng, Lu; Bo, Liu; Gang, Liu; Mu-Sheng, Wu; Chuying, Ouyang

    2016-06-01

    The adsorption and diffusion behaviors of alkali and alkaline-earth metal atoms on silicane and silicene are both investigated by using a first-principles method within the frame of density functional theory. Silicane is staler against the metal adatoms than silicene. Hydrogenation makes the adsorption energies of various metal atoms considered in our calculations on silicane significantly lower than those on silicene. Similar diffusion energy barriers of alkali metal atoms on silicane and silicene could be observed. However, the diffusion energy barriers of alkali-earth metal atoms on silicane are essentially lower than those on silicene due to the small structural distortion and weak interaction between metal atoms and silicane substrate. Combining the adsorption energy with the diffusion energy barriers, it is found that the clustering would occur when depositing metal atoms on perfect hydrogenated silicene with relative high coverage. In order to avoid forming a metal cluster, we need to remove the hydrogen atoms from the silicane substrate to achieve the defective silicane. Our results are helpful for understanding the interaction between metal atoms and silicene-based two-dimensional materials. Project supported by the Natural Science Foundation of Jiangxi Province, China (Grant Nos. 20152ACB21014, 20151BAB202006, and 20142BAB212002) and the Fund from the Jiangxi Provincial Educational Committee, China (Grant No. GJJ14254). Bo Xu is also supported by the Oversea Returned Project from the Ministry of Education, China.

  7. Infrared multiple photon dissociation spectroscopy of cationized methionine: effects of alkali-metal cation size on gas-phase conformation.

    PubMed

    Carl, Damon R; Cooper, Theresa E; Oomens, Jos; Steill, Jeff D; Armentrout, P B

    2010-04-14

    The gas-phase structures of alkali-metal cation complexes of the amino acid methionine (Met) as well as protonated methionine are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser. Spectra of Li(+)(Met) and Na(+)(Met) are similar and relatively simple, whereas the spectra of K(+)(Met), Rb(+)(Met), and Cs(+)(Met) include distinctive new bands. Measured IRMPD spectra are compared to spectra calculated at the B3LYP/6-311+G(d,p) level of theory to identify the conformations present in the experimental studies. For Li(+) and Na(+) complexes, the only conformation present is a charge-solvated, tridentate structure that binds the metal cation to the amine and carbonyl groups of the amino acid backbone and the sulfur atom of the side chain, [N,CO,S]. In addition to the [N,CO,S] conformer, bands corresponding to alkali-metal cation binding to a bidentate zwitterionic structure, [CO(2)(-)], are clearly present for the K(+), Rb(+), and Cs(+) complexes. Theoretical calculations of the lowest energy conformations of Rb(+) and Cs(+) complexes suggest that the experimental spectra could also include contributions from two additional charge-solvated structures, tridentate [COOH,S] and bidentate [COOH]. For H(+)(Met), the IRMPD action spectrum is reproduced by multiple low-energy [N,CO,S] conformers, in which the protonated amine group hydrogen bonds to the carbonyl oxygen atom and the sulfur atom of the amino acid side chain. These [N,CO,S] conformers only differ in their side-chain orientations.

  8. Thermal interface conductance across metal alloy-dielectric interfaces

    NASA Astrophysics Data System (ADS)

    Freedman, Justin P.; Yu, Xiaoxiao; Davis, Robert F.; Gellman, Andrew J.; Malen, Jonathan A.

    2016-01-01

    We present measurements of thermal interface conductance as a function of metal alloy composition. Composition spread alloy films of A uxC u1 -x and A uxP d1 -x solid solutions were deposited on single crystal sapphire substrates via dual electron-beam evaporation. High throughput measurements of thermal interface conductance across the (metal alloy)-sapphire interfaces were made by positional scanning of frequency domain thermoreflectance measurements to sample a continuum of Au atomic fractions (x ˜0 →1 ) . At a temperature of 300 K, the thermal interface conductance at the A uxC u1 -x -sapphire interfaces monotonically decreased from 197 ±39 MW m-2K-1 to 74 ±11 MW m-2K-1 for x =0 →0.95 ±0.02 and at the A uxP d1 -x -sapphire interfaces from 167 ±35 MW m-2K-1 to 60 ±10 MW m-2K-1 for x =0.03 →0.97 ±0.02 . To shed light on the phonon physics at the interface, a Diffuse Mismatch Model for thermal interface conductance with alloys is presented and agrees reasonably with the thermal interface conductance data.

  9. Quantitative EELS analysis of zirconium alloy metal/oxide interfaces.

    PubMed

    Ni, Na; Lozano-Perez, Sergio; Sykes, John; Grovenor, Chris

    2011-01-01

    Zirconium alloys have been long used for fuel cladding and other structural components in water-cooled nuclear reactors, but waterside corrosion is a primary limitation on both high fuel burn-up and extended fuel cycle operation. Understanding the processes that occur at the metal/oxide interface is crucial for a full mechanistic description of the oxidation process. In this paper we show that reliable quantification of the oxygen content at the metal/oxide interface can be obtained by Electron Energy Loss Spectrometry (EELS) if enough care is taken over both the preparation of Transmission Electron Microscopy (TEM) samples and the methodology for quantification of the EELS data. We have reviewed the accuracy of theoretically calculated inelastic partial scattering cross-sections and effective inelastic mean-free-paths for oxygen and zirconium in oxidized Zr-alloy samples. After careful recalibration against a ZrO₂ powder standard, systematic differences in the local oxygen profile across the interface in different zirconium alloys were found. The presence of a sub-stoichiometric oxide layer (a suboxide) was detected under conditions of slow oxide growth but not where growth was more rapid. This difference could arise from the different corrosion resistances of the alloys or, more likely, as a result of the transition in oxidation behaviour, which refers to a sharp increase in the oxidation rate when the oxide is a few microns thick.

  10. Environmental and alloying effects on corrosion of metals and alloys

    NASA Astrophysics Data System (ADS)

    Liang, Dong

    2009-12-01

    In the first part of this project, corrosion studies were carried out on 304L stainless steel samples welded with Cr-free consumables, which were developed to minimize the concentration of chromate species in the weld fume. The corrosion properties of Ni-Cu and Ni-Cu-Pd Gas Tungsten Arc (GTA) welds and Shielded Metal Arc (SMA) welds are comparable to those of welds fabricated with SS308L consumable, which is the standard consumable for welding 304L. Although the breakdown potentials of the new welds from both welding processes are lower than that of the SS308L weld, the repassivation potential of these new welds is much higher. Generally, the repassivation potential is a more conservative measure of susceptibility to localized corrosion. Our studies showed that the Ni-Cu and Ni-Cu-Pd welds are more resistant to crevice corrosion than SS308L welds, which is related to the high repassivation potential. Also, addition of Pd improved the corrosion resistance of the new welds, which is consistent with previous studies from button samples and bead-on-plate samples. Other corrosion studies such as creviced and uncreviced long time immersion, atmospheric exposure, and slow strain rate testing suggest that Ni-Cu-Pd welds can be a qualified substitute for SS308 weld. In the second part of this project, efforts are put on the connection between lab and field exposure tests because sometimes the correspondence between lab atmospheric corrosion tests (ASTM B117) and field exposures is poor as a result of differences in the critical conditions controlling chemical and electrochemical reactions on surfaces. Recent studies in atmospheric chemistry revealed the formation of extremely reactive species from interactions between UV light, chloride aerosols above oceans and oxidizing agents such as ozone or peroxide. Atmospheric corrosion of metals can be affected by these species which might be transported long distances in the atmosphere to locations far from oceans. However, these

  11. To the theory of Ostwald ripening in metallic alloys

    NASA Astrophysics Data System (ADS)

    Ivanskii, B. V.; Vengrenovich, R. D.

    2016-08-01

    The mechanism of growth (dissolution) of nanoparticles controlled simultaneously by the matrix diffusion, diffusion along dislocations, and the rate of the passage of atoms through the interphase boundary (by the rate of formation of interatomic bonds) has been studied in alloys of CuNiAl and AlLi metallic systems at the stage of Ostwald ripening. An expression for the nanoparticle-size distribution function has been obtained, which was calculated based on the dependence of the rate of growth on three fluxes, i.e., diffusion flux j V, dislocation flux j d, and kinetic flux j i . A comparison of the experimental histograms with the theoretically calculated curves indicates their good agreement, which can indicate the opportunity of the realization in practice of the proposed mechanism of growth of nanoparticles in alloys of metallic systems.

  12. A curious interplay in the films of N-heterocyclic carbene PtII complexes upon deposition of alkali metals

    PubMed Central

    Makarova, Anna A.; Grachova, Elena V.; Niedzialek, Dorota; Solomatina, Anastasia I.; Sonntag, Simon; Fedorov, Alexander V.; Vilkov, Oleg Yu.; Neudachina, Vera S.; Laubschat, Clemens; Tunik, Sergey P.; Vyalikh, Denis V.

    2016-01-01

    The recently synthesized series of PtII complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned PtII complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination PtII centre to Pt0 and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system “Pt complex-alkali metal ion”; the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the PtII complexes for a variety of biomedical, sensing, chemical, and electronic applications. PMID:27151364

  13. A curious interplay in the films of N-heterocyclic carbene Pt(II) complexes upon deposition of alkali metals.

    PubMed

    Makarova, Anna A; Grachova, Elena V; Niedzialek, Dorota; Solomatina, Anastasia I; Sonntag, Simon; Fedorov, Alexander V; Vilkov, Oleg Yu; Neudachina, Vera S; Laubschat, Clemens; Tunik, Sergey P; Vyalikh, Denis V

    2016-01-01

    The recently synthesized series of Pt(II) complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned Pt(II) complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination Pt(II) centre to Pt(0) and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system "Pt complex-alkali metal ion"; the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the Pt(II) complexes for a variety of biomedical, sensing, chemical, and electronic applications. PMID:27151364

  14. A curious interplay in the films of N-heterocyclic carbene PtII complexes upon deposition of alkali metals

    NASA Astrophysics Data System (ADS)

    Makarova, Anna A.; Grachova, Elena V.; Niedzialek, Dorota; Solomatina, Anastasia I.; Sonntag, Simon; Fedorov, Alexander V.; Vilkov, Oleg Yu.; Neudachina, Vera S.; Laubschat, Clemens; Tunik, Sergey P.; Vyalikh, Denis V.

    2016-05-01

    The recently synthesized series of PtII complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned PtII complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination PtII centre to Pt0 and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system “Pt complex-alkali metal ion” the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the PtII complexes for a variety of biomedical, sensing, chemical, and electronic applications.

  15. Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms

    SciTech Connect

    Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; DeMille, D. P.

    2007-03-15

    Weak interactions within a nucleus generate a nuclear spin dependent, parity-violating electromagnetic moment, the anapole moment. We analyze a method to measure the nuclear anapole moment through the electric dipole transition it induces between hyperfine states of the ground level. The method requires tight confinement of the atoms to position them at the antinode of a standing wave Fabry-Perot cavity driving the anapole-induced microwave E1 transition. We explore the necessary limits in the number of atoms, excitation fields, trap type, interrogation method, and systematic tests necessary for such measurements in francium, the heaviest alkali.

  16. Sub-Shot-Noise Magnetometry with a Correlated Spin-Relaxation Dominated Alkali-Metal Vapor

    SciTech Connect

    Kominis, I. K.

    2008-02-22

    Spin noise sets fundamental limits to the precision of measurements using spin-polarized atomic vapors, such as performed with sensitive atomic magnetometers. Spin squeezing offers the possibility to extend the measurement precision beyond the standard quantum limit of uncorrelated atoms. Contrary to current understanding, we show that, even in the presence of spin relaxation, spin squeezing can lead to a significant reduction of spin noise, and hence an increase in magnetometric sensitivity, for a long measurement time. This is the case when correlated spin relaxation due to binary alkali-atom collisions dominates independently acting decoherence processes, a situation realized in thermal high atom-density magnetometers and clocks.

  17. 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.

  18. Formation of amorphous metal alloys by chemical vapor deposition

    DOEpatents

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  19. Formation of amorphous metal alloys by chemical vapor deposition

    DOEpatents

    Mullendore, A.W.

    1988-03-18

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures of organometallic compounds and metalloid hydrides,e.g., transition metal carbonyl, such as nickel carbonyl and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit. 1 fig.

  20. The temperature variation of hydrogen diffusion coefficients in metal alloys

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1990-01-01

    Hydrogen diffusion coefficients were measured as a function of temperature for a few metal alloys using an electrochemical evolution technique. Results from these measurements are compared to those obtained by the time-lag method. In all cases, diffusion coefficients obtained by the electrochemical method are larger than those by the time-lag method by an order of magnitude or more. These differences are attributed mainly to hydrogen trapping.