WorldWideScience

Sample records for alkali metal compounds

  1. Superconductivity of graphite intercalation compounds with alkali-metal amalgams

    International Nuclear Information System (INIS)

    Superconductivity of the alkali-metal amalgam graphite intercalation compounds of stage 1 (C4KHg, C4RbHg) and stage 2 (C8KHg, C8RbHg) has been studied as well as that of the pristine amalgams (KHg, RbHg). The transition temperatures are 0.73, 0.99, 1.90, and 1.40 K for C4KHg, C4RbHg, C8KHg, and C8RbHg, respectively. The critical-field anisotropy ratio H/sup parallel//sub c/2/H/sup perpendicular//sub c/2 is about 10 for the stage 1 and about 15 to 40 for the stage 2. It is argued that electrons in the intercalant bands rather than the graphitic bands play the main role in the superconductivity. An interesting feature is that the stage-2 compound, which has a lower density of states at the Fermi level, has a higher transition temperature than the corresponding state-1 compound

  2. 50 years of superbases made from organolithium compounds and heavier alkali metal alkoxides

    Czech Academy of Sciences Publication Activity Database

    Lochmann, Lubomír; Janata, Miroslav

    2014-01-01

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

  3. Ionic conduction in alkali metal doped ZnFe/sub 2/O/sub 4/ compound

    International Nuclear Information System (INIS)

    Zinc ferric oxide (ZnFe/sub 2/O/sub 4/) has been synthesized by liquid phase chemical reaction from aqueous mixture of zinc chloride and ferric chloride in sodium hydroxide (4N) solution and effect of alkali metal on electrical characteristics was explored. The well characterized powder was pressed into pellets and dried at 80 degree C. Samples with alkali metal concentrations 10-100 ppm have been investigated to I-V measurements. The conductivity of pure compound (10-/sub 2/omega-cm)/sup-1/) lies in the semiconductor range but due to alkali metal doping the compound shows ionic conduction at room temperature. The ionic conduction is found to be increased as the dopant concentration increases.(author)

  4. Hydrothermal alkali metal recovery process

    Science.gov (United States)

    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.

  5. Alkali-doped metal-phthalocyanine and pentacene compounds

    NARCIS (Netherlands)

    Craciun, M.F.

    2006-01-01

    The ability to introduce charge carriers in organic molecular materials and control their concentration is of great relevance for both fundamental research and applications. In this thesis, it has been demonstrated that the electronic properties of Metal Phthalocyanines (MPc) and pentacene (PEN) mol

  6. Diffusion of alkali metals in the first stage graphite intercalation compounds by vdW-DFT calculations

    OpenAIRE

    Wang, Zhaohui; Ratvik, Arne Petter; Grande, Tor; Selbach, Sverre Magnus

    2015-01-01

    Diffusion of alkali metal cations in the first stage graphite intercalation compounds (GIC) LiC6, NaC6, NaC8 and KC8 has been investigated with density functional theory (DFT) calculations using the optPBE-vdW van der Waals functional. The formation energies of alkali vacancies, interstitials and Frenkel defects were calculated and vacancies were found to be the dominating point defects. The diffusion coefficients of the alkali metals in GIC were evaluated by a hopping model of point defects ...

  7. Alkali metal ionization detector

    Science.gov (United States)

    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.

  8. Alkali and transition metal phospholides

    International Nuclear Information System (INIS)

    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

  9. Methods of recovering alkali metals

    Science.gov (United States)

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

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

  10. Rapid and efficient synthesis of alkali metal-C[sub 60] compounds in liquid ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Buffinger, D.R.; Ziebarth, R.P.; Stenger, V.A.; Recchia, C.; Pennington, C.H. (Ohio State Univ., Columbus, OH (United States))

    1993-10-06

    The reaction of stoichiometric amounts of alkali metals with C[sub 60] in liquid ammonia provides a rapid and quantitative route to M[sub x]C[sub 60] superconductors (M[sub x] = K[sub 3]/, Rb[sub 3]/, CsRb[sub 2], RbCs[sub 2], KRbCs). Annealing of the samples for 24-48 h at 375[degrees]C is required to obtain large superconducting fractions. [sup 13]C and [sup 87]Rb NMR line shapes are reported for Rb[sub 3]C[sub 60]. The [sup 13]C line shapes show the degree of rotational motion of the C[sub 60] ions varies considerably from sample to sample and is dependent on the method of preparation and subsequent heat treatment. A correlation between the degree of rotational motion and the superconducting fraction is noted and attributed to the amount of disorder in the sample. [sup 87]Rb NMR shows three peaks indicating that Rb[sub 3]C[sub 60] actually contains three different cation sites, rather than the two suggested by X-ray powder diffraction data. The third site is occupied by approximately 15% of the Rb ions in Rb[sub 3]C[sub 60] and is shown to be a subset of the tetrahedral sites in the cubic close-packed C[sub 60] lattice. Although the exact nature of the distortion required to produce the third site is unknown, it appears to be unrelated to the orientations of the C[sub 60] ions creating the site. 18 refs., 2 figs.

  11. Upgrading platform using alkali metals

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

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

  12. Alkali-metal intercalation in carbon nanotubes

    Science.gov (United States)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  13. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    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. Solubility of some phenolic compounds in aqueous alkali metal nitrate solutions from (293.15 to 318.15) K

    International Nuclear Information System (INIS)

    This paper is continuation of the study concerning the solubility-temperature dependence data for some phenolic compounds (PhC), contained in olive mill wastewater (OMWW), in two nitrate salts (KNO3 and NaNO3) aqueous solutions. The solubilities of PhC were determined in the temperature ranging from (293.15 to 318.15) K. It has been observed that the solubility, in aqueous nitrate solutions, increases with increasing temperature. Results showed that alkali metal nitrate has a salting-out effect on the solubility of PhC. The effect of the anion of the electrolyte on the solubility of PhC is observed by comparing these results with values reported in the previous papers for the effect of LiCl, NaCl and KCl. For each cation, the solubilites of the phenolic compounds are higher with nitrate anion than with chloride anion. Results were interpreted in terms of the salt hydration shells and the ability of the solute to form hydrogen-bond with water. The solubility data were accurately correlated by a semi empirical equation. The standard molar Gibbs free energies of transfer of PhC (ΔtrG0) from pure water to aqueous solutions of the nitrate salts have been calculated from the solubility data. The decrease in solubility is correlated to the positive ΔtrG0 value which is mainly of enthalpic origin

  15. Corrosion by the Alkali Metals

    International Nuclear Information System (INIS)

    This is a review of the state of the art of corrosion testing of materials by the alkali metals, the models proposed to explain the observed corrosion results, and the status of materials selection for application in alkali metal-cooled systems. Corrosion of structural and fuel cladding materials by liquid Na and NaK has been studied intensively, but intermittently for the last 18 years. These studies and the liquid-metal-cooled reactors in operation demonstrate that stainless steels can be considered for structural and cladding applications below 650°C. Above this temperature increased corrosion and radiation-induced embrittlement make them unsatisfactory. Corrosion models are reviewed and their inability to explain all the experimental observations discussed. An alternate model is proposed which qualitatively is in agreement with experimental observations. In this model, the rate-controlling step is either the surface reaction of Fe with ''available oxygen'' (dissolved Na2O) to form an Fe-O-Na complex or the rate at which ''available oxygen'' can reach the surface to form the complex; which process is rate controlling depends on the temperature, Na velocity and oxygen concentration in the Na. The solution chemistry of oxygen, carbon and alkali metal-oxygen-transition metal complexes dissolved in the alkali metals is reviewed. ''Molecular'' complexes appear unlikely to exist in solution in the alkali metals, although the thermodynamic tendencies for them to form suggest that stable bonds exist in solution between oxygen, the transition and the alkali metals. The insolubility of carbon in ''oxygen-free'' sodium indicates that carbon transfer may be associated with oxygen in sodium down to very low oxygen levels, although experimental data do not generally confirm this postulate. Corrosion of refractory metals by boiling alkali metals at temperatures above 1000°C is markedly affected by impurities in either the liquid or refractory metal; the addition of Ti, Zr or

  16. Alkali metal sources for OLED devices

    Science.gov (United States)

    Cattaneo, Lorena; Longoni, Giorgio; Bonucci, Antonio; Tominetti, Stefano

    2005-07-01

    In OLED organic layers electron injection is improved by using alkali metals as cathodes, to lower work function or, as dopants of organic layer at cathode interface. The creation of an alkali metal layer can be accomplished through conventional physical vapor deposition from a heated dispenser. However alkali metals are very reactive and must be handled in inert atmosphere all through the entire process. If a contamination takes place, it reduces the lithium deposition rate and also the lithium total yield in a not controlled way. An innovative alkali metal dispensing technology has been developed to overcome these problems and ensure OLED alkali metal cathode reliability. The alkali Metal dispenser, called Alkamax, will be able to release up to a few grams of alkali metals (in particular Li and Cs) throughout the adoption of a very stable form of the alkali metal. Lithium, for example, can be evaporated "on demand": the evaporation could be stopped and re-activated without losing alkali metal yield because the metal not yet consumed remains in its stable form. A full characterization of dispensing material, dispenser configuration and dispensing process has been carried out in order to optimize the evaporation and deposition dynamics of alkali metals layers. The study has been performed applying also inside developed simulations tools.

  17. Superconductivity in alkali metal intercalated iron selenides.

    Science.gov (United States)

    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

  18. Superconductivity in alkali metal intercalated iron selenides

    Science.gov (United States)

    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.

  19. Recovery of alkali metal constituents from catalytic coal conversion residues

    Science.gov (United States)

    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.

  20. Alkali metals in fungi of forest soil

    International Nuclear Information System (INIS)

    The high affinity of forest soil fungi for alkali metals such as potassium, rubidium, caesium as well as radiocaesium is shown and discussed. Good positive correlation was found between K: Rb concentration ratios in soil and in fungi, when correlation between K: Cs concentration ratios was less pronounced. (LN)

  1. Developments in alkali-metal atomic magnetometry

    Science.gov (United States)

    Seltzer, Scott Jeffrey

    Alkali-metal magnetometers use the coherent precession of polarized atomic spins to detect and measure magnetic fields. Recent advances have enabled magnetometers to become competitive with SQUIDs as the most sensitive magnetic field detectors, and they now find use in a variety of areas ranging from medicine and NMR to explosives detection and fundamental physics research. In this thesis we discuss several developments in alkali-metal atomic magnetometry for both practical and fundamental applications. We present a new method of polarizing the alkali atoms by modulating the optical pumping rate at both the linear and quadratic Zeeman resonance frequencies. We demonstrate experimentally that this method enhances the sensitivity of a potassium magnetometer operating in the Earth's field by a factor of 4, and we calculate that it can reduce the orientation-dependent heading error to less than 0.1 nT. We discuss a radio-frequency magnetometer for detection of oscillating magnetic fields with sensitivity better than 0.2 fT/ Hz , which we apply to the observation of nuclear magnetic resonance (NMR) signals from polarized water, as well as nuclear quadrupole resonance (NQR) signals from ammonium nitrate. We demonstrate that a spin-exchange relaxation-free (SERF) magnetometer can measure all three vector components of the magnetic field in an unshielded environment with comparable sensitivity to other devices. We find that octadecyltrichlorosilane (OTS) acts as an anti-relaxation coating for alkali atoms at temperatures below 170°C, allowing them to collide with a glass surface up to 2,000 times before depolarizing, and we present the first demonstration of high-temperature magnetometry with a coated cell. We also describe a reusable alkali vapor cell intended for the study of interactions between alkali atoms and surface coatings. Finally, we explore the use of a cesium-xenon SERF comagnetometer for a proposed measurement of the permanent electric dipole moments (EDMs

  2. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    The coprecipitation of alkali metal ions Li+, Na+, K+ and Rb+ with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na+ which has approximately the same ionic radius as Ca2+. (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li+, Na+, K+ and Rb+) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li+, K+ and Rb+) into the aragonite. (author)

  3. Cathode architectures for alkali metal / oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Study on alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting β''-alumina solid electrolyte (BASE) is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies (20-40%), high power densities (1 W/cm2), 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. (J.P.N.) 79 refs

  5. High-Order Dispersion Coefficients for Alkali-metal Atoms

    Institute of Scientific and Technical Information of China (English)

    KANG Shuai; DING Chi-Kun; CHEN Chang-Yong; WU Xue-Qing

    2013-01-01

    High-order dispersion coefficients C9,C11,C12,and C13 for the ground-state alkali-metals were calculated by combining the l-dependent model potential of alkali-metal atoms and linear variation method based on B-spline basis functions.The results were compared.

  6. The structure of metallic complexes of polyacetylene with alkali metals

    Science.gov (United States)

    Baughman, R. H.; Murthy, N. S.; Miller, G. G.

    1983-07-01

    The crystal structures of sodium, potassium, rubidium, and cesium doped polyacetylene have been determined using crystal packing and x-ray diffraction analyses. Each of these metallic complexes is tetragonal, with the polyacetylene chains forming a host lattice in which the alkali metal ions are present in channels. Lithium appears to be too small to stabilize the channel structure and an amorphous structure is observed. Predicted unit cell parameters and x-ray diffraction intensities are in agreement with observed values. Similarities with the alkali metal doped graphite suggest that hybridization between carbon pz orbitals and metal s orbitals occurs. Such hybridization is expected to result in a high conductivity component normal to the chain direction. On the other hand, direct overlap between polymer chains appears small, since alkali metal columns separate polymer chains. Compositions calculated for the channel structures (from meridional diffraction spacings, the intensity of equatorial diffraction lines, measured volume expansion, and distances in model complexes) all range from y=0.12 to 0.18 for (CHMy)x, where M is sodium, potassium, rubidium, or cesium.

  7. Saturated vapor pressure above the amalgam of alkali metals in discharge lamps

    Science.gov (United States)

    Gavrish, S. V.

    2011-12-01

    A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

  8. The Alkali Metal Interactions with MgO Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtian, Javad [Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi; Bagheri, Zargham [Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of); Kamfiroozi, M. [Islamic Azad University, Shiraz Branch, Shiraz (Iran, Islamic Republic of)

    2012-06-15

    Adsorption of alkali metals (Li, Na, and K) on the surface of magnesium oxide nanotubes (MgONTs) with different diameters was investigated using density functional theory. According to the obtained results, the most stable adsorption site was found to be atop the oxygen atom of the tube surface with adsorption energies in the range of .0.25 to .0.74 eV. HOMO-LUMO gap (E{sub g}) of the tubes dramatically decreases upon the adsorption of the alkali metals, resulting in enhancement of their electrical conductivity enhancement. The order of E{sub g} decrement caused by the metal adsorption is as follows: K > Na > Li. The results suggest that the MgONTs were transformed from semi-insulator to semiconductor upon the alkali metal adsorption. Increasing the tube diameter, the HOMO/LUMO gap of the pristine tube is enhanced and adsorption energies of the alkali metals are decreased

  9. The 4843 Alkali Metal Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    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

  10. Hall Determination of Atomic Radii of Alkali Metals

    Science.gov (United States)

    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.)

  11. Fundamental study on alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

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

  12. Bioinorganic Chemistry of the Alkali Metal Ions.

    Science.gov (United States)

    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

  13. Phonon Dispersion Relations in Alkali Metals

    International Nuclear Information System (INIS)

    It has been shown in this paper that the phonon dispersion curves of sodium in the [100], [110] and [111] symmetry directions can be explained well on the basis of a simple model, where one has to consider only central force constants between nearest and next nearest neighbours. The tangential force constant between the nearest neighbours is very much smaller as compared to the radial force constant, while for the next nearest neighbours the radial and tangential force constants are comparable. The calculation is carried out on the basis of the model suggested by de Launay, where it is shown that the conduction electrons exert a volume force for longitudinal modes. The stiffness constant of the electron gas is its bulk modulus which in de Launay's model is equal to the Cauchy discrepancy (C12-C14) for the cubic crystals. The three force constants α1, α2 and α1' can be determined from the measured elastic constants and the secular equation can be solved to give the dispersion curves. The dispersion curves have also been obtained using the calculated values of the bulk modulus of the electron gas after considering not only the exchange and correlation energies but also the Fermi kinetic energy. These also agree fairly well with experiment. The measured elastic constants as well as calculated bulk modulus of the electron gas indicate that the Cauchy relation C12 = C44 holds good approximately in alkali metals. This result is rather surprising as it requires that the interaction between the atoms be central in nature in spite of the metallic binding. A justification for this has been given by Cochran. A model with four force constants is being worked out. They can be determined from the three elastic constants and calculated bulk modulus of the electron gas. (author)

  14. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN6), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460–490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches. (paper)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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

  18. Transport properties of alkali metal doped fullerides

    International Nuclear Information System (INIS)

    We have studied the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C60 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, Tc, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C60 phonons as 5 K, which is much lower as compared to reported Tc (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. Transport properties of alkali metal doped fullerides

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Daluram, E-mail: daluramyadav@gmail.com; Yadav, Nishchhal, E-mail: somyadav@gmail.com [School of studies in Physics, Vikram University, Ujjain (M.P) India (India)

    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.

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

    International Nuclear Information System (INIS)

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

  1. Electron Mean-Free Paths in the Alkali Metals

    OpenAIRE

    Wertheim, G.K.; Riffe, D. Mark; Smith, N.V.; Citrin, P. H.

    1992-01-01

    Photoemission data in which the signal from the first atomic layer is well resolved from that of the bulk are used to determine accurately the kinetic-energy dependence of the inelastic-electron mean free path in the alkali metals. At the higher kinetic energies, the data are in very good agreement with the theory of Penn. Below about 10 eV, the mean free path in the heavier alkali metals drops markedly below the theoretical values. This is attributed to electron decay processes involvi...

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

    KAUST Repository

    Alahmary, Fatimah S.

    2014-05-01

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

  3. Alkali layered compounds interfaces for energy conversion and energy storage

    Science.gov (United States)

    Papageorgopoulos, Chris A.

    1996-01-01

    During year one a new ultra-high vacuum, an Ar(+) ion sputterer, a low energy electron diffraction (LEED) system, an Auger electron spectrometer (AES), a work function measurement device with a Kelvin probe, and related accessories were used. The study found a focus in the adsorption of chalcogenides on Si and III-V compound semiconductors. In the second year, a scanning tunneling microscope was obtained along with a quadrapole mass spectrometer, power supplies, a computer, a chart recorder, etc. We started the systematic study on the adsorption of chalcogenides on the compound semiconductor surfaces. The third year saw the mounting of the scanning tunneling microscope (STM) on the existing UHV system. The investigation continued with the adsorption of Cs (alkali) on S-covered Si(100)2x1 surfaces. Then the adsorption of S on Cs-covered Si(100) surfaces was studied.

  4. Aqueous alkali metal hydroxide insoluble cellulose ether membrane

    Science.gov (United States)

    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.

  5. Structural models for alkali-metal complexes of polyacetylene

    Science.gov (United States)

    Murthy, N. S.; Shacklette, L. W.; Baughman, R. H.

    1990-02-01

    Structural models for a stage-2 complex are proposed for polyacetylene doped with less than about 0.1 potassium or rubidium atoms per carbon. These structures utilize as a basic motif an alkali-metal column surrounded by four planar-zig-zag polyacetylene chains, a structure found at the highest dopant levels. In the new stage-2 structures, each polyacetylene chain neighbors only one alkali-metal column, so the phase contains four polymer chains per alkali-metal column. Basic structural aspects for stage-1 and stage-2 structures are now established for both potassium- and rubidium-doped polyacetylene. X-ray-diffraction and electrochemical data show that undoped and doped phases coexist at low dopant concentrations (<0.06 K atom per C). X-ray-diffraction data, down to a Bragg spacing of 1.3 Å, for polyacetylene heavily doped with potassium (0.125-0.167 K atom per C) is fully consistent with our previously proposed stage-1 tetragonal unit cell containing two polyacetylene chains per alkali-metal column. There is no evidence for our samples requiring a distortion to a monoclinic unit cell as reported by others for heavily doped samples. The nature of structural transformations and the relationship between structure and electronic properties are discussed for potassium-doped polyacetylene.

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

    Science.gov (United States)

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

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2 SiMe3 )2 and the heavier alkali-metal alkyls M(CH2 SiMe3 ) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2 SiMe3 )3 ] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2 SiMe3 )3 ⋅C6 H6 }2 ] (2) and [{NaMn(CH2 SiMe3 )3 }2 (dioxane)7 ] (5); and to more complex supramolecular networks [{NaMn(CH2 SiMe3 )3 }∞ ] (1) and [{Na2 Mn2 (CH2 SiMe3 )6 (DABCO)2 }∞ ] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6 K2 Mn2 (CH2 SiMe3 )4 (O(CH2 )2 OCH=CH2 )2 }∞ ] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways. PMID:26916525

  7. Apparatus for use in a liquid alkali metal environment

    International Nuclear Information System (INIS)

    Apparatus is described for use in a liquid alkali metal environment consisting of components having complementary bearing surfaces in which one of the components has a bearing surface of stainless steel and another of the components has an aluminised complementary bearing surface. Examples are given of the use of the invention in heat exchange apparatus in liquid metal cooled fast breeder reactors; one example is in connection with the fuel subassembly in such a reactor. (U.K.)

  8. Active-alkali metal promoted reductive desulfurization of dibenzothiophene and its hindered analogues

    OpenAIRE

    Pittalis, Mario; Azzena, Ugo Gavino; Carraro, Massimo; Pisano, Luisa

    2013-01-01

    Reductive desulfurisation of organic compounds is of importance both in organic synthesis and in industry. Benzo- and dibenzothiophenes are between the most abundant sulphur containing impurities in crude oils, and their desulfurization is a mandatory issue in the production of non polluting fuels. Following our interest in the development of efficient alkali metal-mediated synthetic procedures and alternative protocols for the chemical transformation of widespread environmental contaminants ...

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

    Indian Academy of Sciences (India)

    Prasenjit Sen

    2010-04-01

    Electronic and magnetic structures of (1 0 0) films of K and Cs, having thicknesses of one to seven layers, are calculated within the plane-wave projector augmented wave (PAW) formalism of the density functional theory (DFT), using both local spin density approximation (LSDA) and the PW91 generalized gradient approximation (GGA). Only a six-layer Cs film is found to have a ferromagnetic (FM) state which is degenerate with a paramagnetic (PM) state within the accuracy of these calculations. These results are compared with those obtained from calculations on a finite-thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films and bulk hosts are also discussed.

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

    International Nuclear Information System (INIS)

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

  11. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad; J.; M.; PAPIS; Joerg; F.; LOEFFLER; Peter; J.; UGGOWITZER

    2009-01-01

    Compound casting’simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, ‘compound casting’ of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu- ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and Al12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protective coating to the substrate.

  12. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad J.M.PAPIS; Joerg F.LOEFFLER; Peter J.UGGOWITZER

    2009-01-01

    'Compound casting'simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, 'compound casting' of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu-ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and AI12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protec-tive coating to the substrate.

  13. Chemical compatibility of structural materials in alkali metals

    International Nuclear Information System (INIS)

    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

  14. Chemical compatibility of structural materials in alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L.; Haglund, R. [Argonne National Lab., Chicago, IL (United States)] [and others

    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.

  15. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Science.gov (United States)

    2010-07-01

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

  16. Synthesis, structure peculiarities and electric conductivity of alkali metal-rare earth silicates (germanates)

    International Nuclear Information System (INIS)

    The process of obtaining of rare earth-alkali metal silicates (germanates) is studied. The analysis of possibilities of structural disordering of alkaline cations in these structures is given. The interaction of the structure of different by the composition alkali alkali metal - rare earth silicates with electric conductivity values is shown

  17. Synthesis and Structural Characterization of Alkali Metal Guanidinates

    Institute of Scientific and Technical Information of China (English)

    LUO,Yun-Jie; YAO,Ying-Ming; ZHANG,Yong; SHEN,Qi

    2007-01-01

    Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides,MN(SiMe3)2(M=Li or Na)in hexane or THF produced the alkali metal guanidinates{(j-PrN)2C[N(SiMe3)2]Li}2(1)and{(i-PrN)2C[N(SiMe3)2]Na(THF)}2(2)in nearly quantitative yields.Both complexes 1 and 2 were well characterized by elemental analysis,IR spectra,1H and 13C NMR spectra,and X-ray diffraction.It was found that the guanidinates adopt different coordination modes in these complexes.

  18. Polarizabilities and hyperpolarizabilities of the alkali metal atoms

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-08-14

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

  19. Inner-shell excitation of alkali-metal atoms

    International Nuclear Information System (INIS)

    Inner-shell excitation of alkali-metal atoms, which leads to auto-ionization, is reviewed. The validity of quantum mechanical approximation is analyzed and the importance of exchange and correlation is demonstrated. Basic difficulties in making accurate calculations for inner-shell excitation process are discussed. Suggestions are made for further study of inner-shell process in atoms and ions. (author). 26 refs, 4 figs, 1 tab

  20. Dissolution of metallic uranium in alkalis

    International Nuclear Information System (INIS)

    The dissolution of U metallic foils has been studied in the framework of the development of an improved 99Mo-production process. The best conditions for the dissolution of uranium foils of approximately 150 μm are the following: a) NaClO concentrations of 0.20 and 0.23 M with NaOH of 0.27 and 0.31 M respectively; b) temperature of the solution, 70 C degrees; c) volume of the solution, 15 ml / cm2 of uranium foil; d) dissolution time, 30 minutes. (author)

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

    Science.gov (United States)

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

    Perfluorocarbons (PFCs) are the most potent green house gases that are very recalcitrant at destruction. An effective way of converting PFCs using hot solid reagents into safe products has been recently introduced. By investigating the thermal reductive destruction of tetrafluoromethane (CF4) we provided new insight and more physicochemical consideration on this novel process. The complete destruction of CF4was successfully achieved by flowing the gas through a heated reagent bed (400-950 degrees C) that contained powder mixtures of alkali halides, CaO, and Si. The silicon acted as a reducing agent of alkali halides for the in-situ production of alkali metals, and the calcium oxide played the role of a halide ion acceptor. The absence of any single component in this ternary mixture drastically reduced the destruction efficiency of CF4. The CF4 destruction efficiencies with the solid reagent containing the alkali halide, MX, increased in the order of Li approximately Na < K < Cs for alkali cations and I < Br < Cl < F for halide anions. This trend agreed with the endothermicity of the alkali metal generation reaction: the higher the endothermicity, the lower the destruction efficiency. Alkali metal generation was indirectly detected by monitoring H2 production from its reaction with water. The production of alkali metals increased with NaF, KF, and CsF in this order. The CsF/CaO/Si system exhibited the complete destruction of CF4 at as low as 600 degrees C. The solid product analysis by X-ray diffraction (XRD) showed the formation of CaF2 and the depletion of Si with black carbon particles formed in the solid reagent residue. No CO/CO2 and toxic HF and SiF4 formation were detected in the exhaust gas. PMID:11944694

  2. Behaviour of gaseous alkali compounds in coal gasification; Kaasumaisten alkaliyhdisteiden kaeyttaeytyminen kivihiilien kaasutuksessa

    Energy Technology Data Exchange (ETDEWEB)

    Nykaenen, J. [Imatran Voima Oy, Vantaa (Finland)

    1997-10-01

    In this project the behaviour of alkali compounds emitting from CO{sub 2}/O{sub 2}- and airblown gasification are studied. This research project is closely connected to an EU-project coordinated by the Delft University of Technology (DUT). In that project alkali emissions from a 1.6 MW pilot plant will be measured. The results from those measurements will be compared with the calculations performed in this LIEKKI 2 project. The equilibrium calculations show that the major gaseous alkali compounds emitting from combustion and gasification are chlorides and hydroxides. This applies both to air- and CO{sub 2}/O{sub 2}-blown processes. In all the cases studied the concentration of gaseous alkali compounds is determined mainly by the amount of chlorides. The key parameters, with respect to alkali behaviour, are the temperature of the process and chlorine content of the coal. By cooling the gases down to 600 deg C prior to a ceramic filter the alkali concentration can be kept about at 100 ppbv. In combustion, the addition of calcium carbonate increases the amount of gaseous alkali compounds by decreasing the amount of alkali sulphates. In the case of gasification the importance of limestone is negligible. The difference between air- and CO{sub 2}/O{sub 2}-blown processes, in terms of gaseous alkali emissions, is small. This is because CO{sub 2} concentration of the gas does not have a strong impact on alkali chlorides. Furthermore, the effect of CO{sub 2}/O{sub 2}-ratio of the recirculation process is negligible. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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)

  5. Quasiparticle electronic band structure of the alkali metal chalcogenides

    Directory of Open Access Journals (Sweden)

    S.V. Syrotyuk

    2015-09-01

    Full Text Available The electronic energy band spectra of the alkali metal chalcogenides M2A (M: Li, Na, K, Rb; A: O, S, Se, Te have been evaluated within the projector augmented waves (PAW approach by means of the ABINIT code. The Kohn-Sham single-particle states have been found in the GGA framework. Further, on the basis of these results the quasiparticle energies of electrons as well as the dielectric constants were obtained in the approximation GW. The calculations based on the Green's function have been originally done for all the considered M2A crystals, except Li2O.

  6. Work function of alkali metal-adsorbed molybdenium dichalcogenides

    Science.gov (United States)

    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.

  7. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    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

  8. Freezing of liquid alkali metals as screened ionic plasmas

    International Nuclear Information System (INIS)

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

  9. Alkali Metal Complexes: Mixed Ligand Complexes of Some Alkali Metal Salts of Some Organic Acids with Isonitroso-PMethylace to phenone

    Directory of Open Access Journals (Sweden)

    O.P. Gupta

    2016-02-01

    Full Text Available A number of mixed ligand complexes of alkali metal salts of o-nitrophenol,2,4-dinitrophenol, 2,4,6,- trinitrophenol, 1-nitroso-2- naphthol and 8- hydroxyquinoline with Insoniroso–p methylacetopheone have been synthesized in absolute ethanol & characterized by elemental analysis and I .B. spectral data. Their I.R spectral data indicate the presence of hydrogen bonding in them, which many be one of the dominant factors of their stability. Further appreciable shift in 1650 cm-1 band (possibly vC=O and 1600 cm-1 band (possibly vC=NSuggests their coordination behavior in these mixed ligand complexes The reactions that take place in natural systems are highly specific and selective. Alkali metal ions actively participate in most of the reaction occurring in the biological systems, which are dominated by mixed ligand complexes. Studies of such mixed ligand complexes of alkali metals can threw light in understanding the role and mechanism of selective absorption of alkali metals ions by plants Coordinating ability of alkali metal with isonitrosoacetophenone1-2 and transition metals with isonitrosoacetophenone3 and isonitroso-p-methylacetophenone4 have been reported earlier. In the present paper we report the mixed ligand complexes of alkali metal salts having the general formula ML.HL, ‘ where M=Li, Na & K and L=deprotonated o- nitrophenol, 2,4 dinitrophenol, 2, 4, 6- trinitrophenol, 1-nitroso-2-naphthol or 8- hydroxquinoline; HL’= p -MeHINAP (isonitroso-p-methylacetophenone.

  10. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    Energy Technology Data Exchange (ETDEWEB)

    None

    1991-12-01

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

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

    International Nuclear Information System (INIS)

    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

  12. Density dependence of the diffusion coefficient of alkali metals

    International Nuclear Information System (INIS)

    The effect of density on transport coefficients of liquid Li, Na and K at high temperatures using the method of Molecular Dynamics simulation has been studied. Simulation of these liquid alkali metals were carried out with 800 particles in simulation boxes with periodic boundary conditions imposed. In order to test the reliability of the interatomic potential used in the calculations, experimental data on the structural properties were compared with calculated results. The calculations showed a linear relationship between the density and the diffusion coefficient in all the systems investigated except in lithium, where, due to the small size of the atom, standard molecular dynamics simulation method may not be appropriate for calculating the properties of interest. (author)

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

    International Nuclear Information System (INIS)

    It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from 3Li to 37Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton profile are found to be in good agreement with the results of more detailed configuration-interaction calculations for the atom 3Li. Similar results for 11Na, 19K and 37Rb are compared with the corresponding Hartree-Fock-Roothan values only, for want of data from other realistic calculations. (author)

  14. Alkali metal thermoelectric conversion (AMTEC) technology status review

    International Nuclear Information System (INIS)

    The Alkali Metal Thermoelectric Converter (AMTEC) or sodium heat engine has been the subject of experimental and systems investigations to assess its potential and feasibility for several space and terrestrial power applications. AMTEC is a thermally regenerative electrochemical system operating between a high temperature reservoir at 900-1400K and a sodium condenser at 400-BOOK. Its operation is based on the sodium ion conductor beta-alumina solid electrolyte(BASE), where thermal to electric conversion efficiencies of 20-40% have been predicted for practical systems. Other AMTEC characteristics that make it attractive for space applications are compactness, light weight, no moving parts, modularity and long lifetime potential. This paper reviews AMTEC operating principles and technical challenges, reports on recent electrode research results, and summarizes the status of AMTEC device experiments at JPL and elsewhere. Also, updated projections for AMTEC space nuclear power system characteristics is presented

  15. Relativistic optimized effective potential method-application to alkali metals.

    Science.gov (United States)

    Ködderitzsch, D; Ebert, H; Akai, H; Engel, E

    2009-02-11

    We present a relativistic formulation of the optimized effective potential method (ROEP) and its implementation within the Korringa-Kohn-Rostoker multiple scattering formalism. The scheme is an all-electron approach, treating core and band states formally on the same footing. We use exact exchange (EXX) as an approximation to the exchange correlation functional. Numerical four-component wavefunctions for the description of core and valence electrons and the corresponding ingredients of the ROEP integral equation are employed. The exact exchange expression for the valence states is reformulated in terms of the electronic Green's function that in turn is evaluated by making use of multiple scattering formalism. We present and discuss the application of the formalism to non-magnetic alkali metals. PMID:21715911

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

    International Nuclear Information System (INIS)

    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

  17. Theoretical investigation of the interaction of cytosine and its tautomers with alkali metals

    International Nuclear Information System (INIS)

    Quantum-chemical calculations have been applied in order to explore the interaction of alkali metals (M=Li-Cs) with cytosine and its tautomers. The optimized geometries, harmonic vibrational frequencies, and the energies of cytosine, metallated cytosine, and its tautomers have been calculated. The calculations show that metallated cytosine is more stable than non metallated one. The stability of metallated cytosine decreases with the growth of atomic number of alkali metals. Estimated charge on the metals demonstrates that there is some covalency in the metal-ligand interaction, especially in the Li+ system

  18. Generation and alteration of the defects induced by particle irradiation and electromagnetic radiation in alkali halogen compounds

    International Nuclear Information System (INIS)

    Interactions between electron beams, CO2 - laser radiation and alkali halogen compound have led to interesting results: 1. The development of two types of F-centre respectively in normal lattice or near the dislocations. 2. The beginning of metal colloids development process at low temperature when a thermal treatment is applied. 3. An experimental confirmation of the Pooley-Hersh model for crystal defects has been brought up. 4. The surface penetration is an explosive process. 5. Surface polygonizations were also investigated. A model has been proposed to describe the destructive channels development within alkali halogen crystals with molecular anions impurities of less than 10 ppm. KCl monocrystals of advanced purity level was prepared for building up passive optical components of strong CO2 lasers. (author)

  19. Structural properties of low-density liquid alkali metals

    Indian Academy of Sciences (India)

    A Akande; G A Adebayo; O Akinlade

    2005-12-01

    The static structure factors of liquid alkali metals have been modelled at temperatures close to their melting points and a few higher temperatures using the reverse Monte Carlo (RMC) method. The positions of 5000 atoms in a box, with full periodicity, were altered until the experimental diffraction data of the structure factor agrees with the associated model structure factor within the errors. The model generated is then analysed. The position of the first peak of the pair distribution function () does not show any significant temperature dependence and the mean bond lengths can be approximated within an interval of 3.6–5.3 Å, 4.5–6.6 Å, 4.8–6.7 Å and 5.1–7.3 Å for Na, K, Rb and Cs respectively. The cosine bond distributions show similar trend with the flattening up of the first peak with increase in temperature. In addition, the coordination numbers of these liquid metals are high due to the presence of non-covalent bonding between them. On the average, we surmise that the coordination number decreases with increase in temperature.

  20. Field emission properties of capped carbon nanotubes doped by alkali metals:a theoretical investigation

    Institute of Scientific and Technical Information of China (English)

    Jin Lei; Fu Hong-Gang; Xie Ying; Yu Hai-Tao

    2012-01-01

    The electronic structures and field emission properties of capped CNT55 systems with or without alkali metal atom adsorption were systematically investigated by density functional theory calculation.The results indicate that the adsorption of alkali metal on the center site of a CNT tip is energetically favorable.In addition,the adsorption energies increase with the introduction of the electric field.The excessive negative charges on CNT tips make electron emittance much easier and result in a decrease in work function.Furthermore,the inducing effect by positively charged alkali metal atoms can be reasonably considered as the dominant reason for the improvement in field emission properties.

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

    International Nuclear Information System (INIS)

    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

  2. Sorption selectivity of alkali metal ions in polymer inclusion ion exchange membranes

    International Nuclear Information System (INIS)

    Sorption selectivity of different alkali metal ions in polymer inclusion cation exchange membranes has been studied. The concentration of the metal ions were measured using neutron activation analysis. The results show the selectivity of polymer inclusion membranes for metal ions in the order Na++++. The trend have been explained in terms of the radius of the hydrated metal ion. (author)

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

    Science.gov (United States)

    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.

  4. Study on the electrode characteristics of alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter utilizing the sodium ion conducting β''-alumina is a device to convert directly heat energy to electric energy. It is characterized by high conversion efficiencies, high power densities, no moving parts and low maintenance requirements. Because of these merits, AMTEC is one of the most promising candidate for aerospace power systems, remote power station and dispersed small scale power station. In this paper, the experimental results of the disk type cell and the theoretical considerations about internal resistances have been reported. The film electrode was made with a magnetron sputtering system. The open voltage of 0.98 V and the maximum power density of 0.38 W/cm2 at the sodium temperature of 1,073 K have been obtained. It became clear after the theoretical investigation on the internal resistance that the most largest internal resistance was the resistance of β''-alumina. And so, it is necessary to reduce the thickness of β''-alumina to improve the generating power densities. It was also clarified that the sodium gas flow in the small holes of molybdenum thin film electrode was a free molecular flow and the experimental results became agree well with the theoretical results considering the pressure rise due to this sodium free molecular flow. It was also necessary to develop the more porous and lower resistivity thin film electrodes because this pressure rise were fairly large. (author)

  5. Corrosion in alkali metal/molybdenum heat pipes

    International Nuclear Information System (INIS)

    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

  6. First-principles study of ternary graphite compounds cointercalated with alkali atoms (Li, Na, and K) and alkylamines towards alkali ion battery applications

    Science.gov (United States)

    Ri, Gum-Chol; Yu, Chol-Jun; Kim, Jin-Song; Hong, Song-Nam; Jong, Un-Gi; Ri, Mun-Hyok

    2016-08-01

    First-principles calculations were carried out to investigate the structural, energetic, and electronic properties of ternary graphite compounds cointercalated with alkali atoms (AM = Li, Na, and K) and normal alkylamine molecules (nCx; x = 1, 2, 3, 4), denoted as AM-nCx-GICs. From the optimization of the orthorhombic unit cells for the crystalline compounds, it was found that, with the increase in the atomic number of alkali atoms, the layer separations decrease in contrast to AM-GICs, while the bond lengths between alkali atoms and graphene layer, and nitrogen atom of alkylamine increase. The calculated formation energies and interlayer binding energies of AM-nC3-GICs indicate that the compounds is increasingly stabilized from Li to K, and the energy barriers for migration of alkali atoms suggest that alkali cation with larger ionic radius diffuses more smoothly in graphite, being similar to AM-GICs. Through the analysis of electronic properties, it was established that more extent of electronic charge is transferred from more electropositive alkali atom to the carbon ring of graphene layer, and the hybridization of valence electron orbitals between alkylamine molecules and graphene layer is occurred.

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

    Science.gov (United States)

    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.

  8. The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

    OpenAIRE

    Previdello, B.; E. Machado; Varela, H.

    2014-01-01

    Non-covalent interactions between hydrated alkali metal cations and adsorbed oxygenated species on platinum might considerably inhibit some electrocatalytic reactions. We report in this communication the effect exerted by electrolyte alkali metal cations on the electro-oxidation of formate ions on platinum. The system was investigated by means of cyclic voltammetry and chronoamperometry in the presence of an electrolyte containing Li+, Na+, or K+. As already observed for other systems, the ge...

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-03-21

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

  11. Ab initio studies of structural, electronic, magnetic and mechanical properties of alkali earth metal silicides

    International Nuclear Information System (INIS)

    Alkali earth metal silicides MSi (M = Mg, Ca, Sr, Ba) are multi-phase compound and exist simultaneously in CrB, CsCl, NaCl or rock salt (RS) and zinc blende (zb) structures. In the CrB and CsCl phases, their behavior is metallic in the non-magnetic (NM) as well as the ferromagnetic (FM) structure. The total spin magnetic moment of these compounds in the zb phase is more than that in the corresponding RS phase; therefore, detailed studies for the zb phase are presented in this paper. This study includes structural, electronic and mechanical properties by using the full potential linear augmented plain wave scheme with local orbitals. Ferromagnetic CaSi, SrSi and BaSi show true half-metallic character. For a better understanding of the half-metallicity in the above-mentioned sp-type compounds, their band structures have been calculated and densities of state plots have been produced. The FM structures are more stable and harder than the corresponding NM structures. The magnetic moment corresponding to equilibrium lattice constants is calculated as 2 µB for FM CaSi, SrSi and BaSi, which are in accordance with the earlier work on the sp-type compounds CaC, SrC and BaC. The FM character changes to the paramagnetic character as the lattice parameter decreases. The general trend is that the values of the elastic constants C11, C12 and C44 increase with increasing hydrostatic pressure

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

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, A., E-mail: rrpalanichamy@gmail.com; Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com; Santhosh, M., E-mail: rrpalanichamy@gmail.com; Sudhapriyanga, G., E-mail: rrpalanichamy@gmail.com [Department of Physics, N.M.S.S.V.N College, Madurai, Tamilnadu-625019 (India); Kanagaprabha, S. [Department of Physics, Kamaraj College, Tuticorin, Tamil Nadu-628003 (India)

    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.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-02-01

    The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge. PMID:26650573

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

  16. Behaviour of gaseous alkali compounds from coal gasification; Kaasumaisten alkaliyhdisteiden kaeyttaeytyminen kivihiilen kaasutuksessa

    Energy Technology Data Exchange (ETDEWEB)

    Nykaenen, J. [Imatran Voima Oy, Vantaa (Finland)

    1996-12-01

    In this project the behaviour of alkali compounds has been studied with a chemical equilibrium model. The goal is to evaluate the possibilities to remove the sodium and potassium compounds together with the fly ash particles by using a ceramic honeycomb filter. The studied processes include both CO{sub 2}/O{sub 2}- and air-blown gasification and combustion. The results show that the difference between the processes with flue gas recirculation and air-blown processes is small. This is due to that the equilibrium concentration of the dominant gaseous alkali compound, chloride, is more or less the same in both processes. This research project is closely connected to the EU-project coordinated by the Delft University of Technology (DUT). In that project alkali concentration of the fuel gas from a 1.6 MW pilot plant will be measured. During the next phase of this research the results from DUT will be compared with the results of this presentation. (author)

  17. Lattice-gas model for alkali-metal fullerides: face-centered-cubic structure

    OpenAIRE

    Udvardi, Laszlo; Szabo, Gyorgy

    1995-01-01

    A lattice-gas model is suggested for describing the ordering phenomena in alkali-metal fullerides of face-centered-cubic structure assuming the electric charge of alkali ions residing in either octahedral or tetrahedral interstitial sites is completely screened by the first-neighbor C_60 molecules. This approximation allows us to derive an effective ion-ion interaction. The van der Waals interaction between the ion and C_60 molecule is characterized by introducing an additional energy at the ...

  18. Adsorption of volatile organic compounds in porous metal-organic frameworks functionalized by polyoxometalates

    International Nuclear Information System (INIS)

    The functionalization of porous metal-organic frameworks (Cu3(BTC)2) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N2 and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols (C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies estimated by the modified Clausius-Clapeyron equation provided insight into the impact of POMs and alkali metal cations on the adsorption of VOCs. The introduction of POMs not only improved the stability, but also brought the increase of adsorption capacity by strengthening the interaction with gas molecules. Furthermore, the exchanged alkali metal cations acted as active sites to interact with adsorbates and enhanced the adsorption of VOCs. - Graphical Abstract: The adsorption behavior of volatile organic compounds in porous metal-organic frameworks functionalized by polyoxometalates has been systematically evaluated. Highlights: → Functionalization of MOFs was achieved by incorporating Keggin-type POMs. → Introduction of POMs improved the thermal stability and adsorption capacity. → Alkali metal ion-exchange modified the inclusion state and also enhanced the adsorption. → Adsorption enthalpies were estimated to study the impact of POMs and alkali metal cations.

  19. Enrichment of hydrogen isotopes while decomposition of alkali metal amalgams (Preprint No. CA-11)

    International Nuclear Information System (INIS)

    Sodium amalgam was prepared by electrolyzing caustic soda solution in a cell with flowing mercury as cathode. On decomposition of amalgam with aqueous sodium hydroxide solution in a denuder column packed with graphite pieces, the resultant hydrogen gas was depleted in deuterium. The alkali solution was enriched in deuterium content. The separation of the isotopes of some amalgam forming metals while decomposition of the amalgam of these metals with water has already been described. The separation is due to differential reaction rates of alkali metal amalgams with water containing light and heavy isotopes of hydrogen. However in the present investigation, the separation factor obtained is considerably higher than earlier reported due to possible chemical exchange between resultant hydrogen and the alkali metal hydroxide in presence of graphite surface and/or exchange of water with nascent hydrogen catalysed by OH- ions. (author). 18 refs., 3 tabs., 1 fig

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

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2008-01-01

    In aqueous solutions, the alkali metals ions are associated with a number of H2O molecules. A distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and a secondary (or outer) solvation shell, consisting of...... all other water molecules whose properties are still influenced significantly by the cation. Knowing the hydration number is important when considering, for instance, the transport of Na+ and K+ in biological cell membranes, since their different behavior may depend on the details of ion hydration....... The solvation of alkali metal ions has been discussed for many years without a clear consensus. This work presents a systematic study of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile...

  1. Charge oscillations and structure for alkali-metal-doped polyacetylene

    Science.gov (United States)

    Baughman, R. H.; Murthy, N. S.; Eckhardt, H.; Kertesz, M.

    1992-11-01

    predictions for oligomers, and good agreement is obtained between calculated and observed x-ray photoelectron spectra for sodium-doped polyacetylene. Emphasis is placed on the results of crystallographic studies of alkali-metal-doped polyacetylene and on the relationship between the experimentally derived symmetry breaking in interchain packing and the molecular symmetry breaking predicted by theory. Since presently available experimental data are insufficient for complete determination of structure, the present theoretical results can be useful for refinements in the interpretation of these data, as well as for refined crystal-packing calculations.

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

    Science.gov (United States)

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

    2013-01-01

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

  3. POLARIZATION EFFECTS IN XANES OF LAYERED MATERIALS : ALKALI-GRAPHITE INTERCALATION COMPOUNDS STUDY

    OpenAIRE

    FrÉtigny, C.; Bonnin, D.; Cortès, R.

    1986-01-01

    X-ray absorption spectra in the near edge region of alkali graphite intercalation compounds are reported. MC8 and MC24 (M = K, Rb, Cs) compounds are lamellar and their spectra exhibit a high orientation dependence. At each energy, a linear regression analysis of the absorption for different incidence angles (θ ≤ 40°) permits to obtain the limiting case spectrum θ = 90°. In the case of potassium, where the core hole lifetime is large, implying a small broadening of the spectra, comparison is m...

  4. Elimination technique for alkali metal ion adducts from an electrospray ionization process using an on-line ion suppressor

    OpenAIRE

    NOZAKI, Kazuyoshi; TARUI, Akira; OSAKA, Issey; Kawasaki, Hideya; ARAKAWA, Ryuichi; 荒川, 隆一

    2010-01-01

    The effects of an on-line ion suppressor device on alkali metal ion adduct formations of the model compound tacrolimus were investigated. The base peak ion in the positive ion ESI-MS spectrum of tacrolimus was a sodium ion adduct, [M+Na]+. On the other hand, an ammonium ion adduct, [M+NH4]+, was the base peak ion in the full-scan mass spectrum of tacrolimus with a cation-exchange suppressor resin, and both [M+Na]+ and [M+K]+ were eliminated. These results indicate that the combination of an o...

  5. Synthesis and properties of alkali metal intercalated fullerene-like MS2 (M=W,Mo) nanoparticles

    International Nuclear Information System (INIS)

    Layered metal disulfides - MoS2 and WS2 in the form of fullerene-like (IF) nanoparticles and in the form of platelets (crystallites of the 2H polytype) have been intercalated by exposure to alkali metal (potassium and sodium) vapor using a two-zone transport method. The composition of the intercalated systems was established using X-ray energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). X-ray powder diffraction (XRD) analysis and transmission electron microscopy (TEM) of the samples, which were not exposed to the ambient atmosphere, showed that they suffered little change in their lattice parameters. On the other hand, after exposure to ambient atmosphere, substantial increase in the interplanar spacing (3-5 Aa) was observed for the intercalated phases. Insertion of one to two water molecules per intercalated metal atom was suggested as a possible explanation for this large expansion along the c-axis. The modifications in magnetic and transport properties of the intercalated materials were investigated, and are believed to occur via charge transfer from the alkali metal to the conduction band of the host lattice. Restacking of the MS2 layers after prolonged exposure to the atmosphere and recovery of the pristine compound properties were observed as a result of deintercalation of the metal atoms

  6. From carbanions to organometallic compounds: quantification of metal ion effects on nucleophilic reactivities.

    Science.gov (United States)

    Corral-Bautista, Francisco; Klier, Lydia; Knochel, Paul; Mayr, Herbert

    2015-10-12

    The influence of the metal on the nucleophilic reactivities of indenyl metal compounds was quantitatively determined by kinetic investigations of their reactions with benzhydrylium ions (Ar2 CH(+) ) and structurally related quinone methides. With the correlation equation log k2 =sN (N+E), it can be derived that the ionic indenyl alkali compounds are 10(18) to 10(24) times more reactive (depending on the reference electrophile) than the corresponding indenyltrimethylsilane. PMID:25951612

  7. Thermochemistry of complex oxides of uranium(6), arsenic and alkali metals

    International Nuclear Information System (INIS)

    Standard reaction enthalpies for stoichiometric mixtures of mono-potassium orthoarsenate, uranium(6) and alkali metal nitrate oxides as well as mixtures of complex oxides of the M1AsUO6 (M1 = Li, Na, K, Rb, Cs) general formulas and potassium nitrate with hydrofluoric acid are determined in adiabatic calorimeter at the temperature of 298.15 K. Standard enthalpies for formation of complex oxides of uranium(6), arsenic and alkali metals at the temperature of 298.15 K are calculated by the obtained results. 8 refs., 1 tab

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

    International Nuclear Information System (INIS)

    Volatilities of GaCl3 and alkali metal chlorides over diluted (up to 3 mol %) solutions of GaCl3 in LiCl, NaCl, KCl, RbCl, and CsCl were measured at 1100 K by dynamic and indirect static methods. Chemical composition of saturated vapor over the mixed melts was determined. Partial pressures of the components were calculated. Their values depend essentially on specific alkali metal cation and on concentration of GaCl3; their variation permits altering parameters of GaCl3 distillation from the salt melt in a wide range

  9. Hydration to the poly(oxyethylene) derivative complexes of alkali metal ions and barium ion in 1,2-dichloroethane

    International Nuclear Information System (INIS)

    A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, XH2O,S, and its complex, XH2O,comp, in water saturated with 1,2-DCE was determined by means of aquametry. The XH2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The XH2O,comp value decreases in the order Li+>Na+>K+≅Rb+≅Cs+ in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the XH2O,comp values of barium ion complexes are smaller than those of potassium ion complexes. (author)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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.

  13. Model for H-, D- production by hydrogen backscattering from alkali and alkali/transition-metal surfaces

    International Nuclear Information System (INIS)

    A model for H-, D- production by energetic particles reflecting from metal surfaces is discussed. The model employs the energy and angular distribution data derived from the Marlowe code. The model is applied to particles incident normally upon Cs, Ni, and Cs/Ni surfaces

  14. Phonon dispersion in alkali metals and their equiatomic sodium-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    Aditya M. VORA

    2008-01-01

    In the present article, the theoretical calcula-tions of the phonon dispersion curves (PDCs) of five alkali metals viz. Li, Na, K, Rb, Cs and their four equia-tomic sodium-based binary alloys viz. Na0.5Li0.5,Na0.5K0.5, Na0.5Rb0.5 and Na0.5Cs0.5 to second order in a local model potential is discussed in terms of the real-space sum of the Born yon Karman central force con-stants. Instead of the concentration average of the force constants of pure alkali metals, the pseudo-alloy-atom (PAA) is adopted to directly compute the force constants of the four equiatomic sodium based binary alloys and was successfully applied. The exchange and correlation functions due to the Hartree (H) and Ichimaru-Utsumi (IU) are used to investigate the influence of the screening effects. The phonon frequencies of alkali metals and their four equiatomic sodium-based binary alloys in the longit-udinal branch are more sensitive to the exchange and cor-relation effects in comparison with the transverse branches. The PDCs of pure alkali metals are found in qualitative agreement with the available experimental data. The frequencies in the longitudinal branch are sup-pressed rather due to IU-screening function than those due to static H-screening function.

  15. Modified PVA-CA blend ultrafiltration membrane by alkali metal chloride

    Institute of Scientific and Technical Information of China (English)

    张启修; 邱运仁

    2003-01-01

    The modified PVA-CA blend ultrafiltration membranes were prepared by phase inversion from the casting solutions consisting of polyvinyl alcohol(PVA), cellulose acetate(CA), acetic acid, alkali metal chloride and water. The effects of different concentration of alkali metal chloride on the properties of membranes were investigated. The results show that when the mass fraction of the salt in the casting solution is not greater than 1%, the property of rejection of the alkali metal salt modified ultrafiltration PVA-CA blend membrane has little change compared with that of the unmodified PVA-CA blend membrane, but the permeation flux is much greater than that of the unmodified membrane under the same operation condition. When the mass fraction of the salt is greater than 1.5%, the permeate flux increases much greater than that of the unmodified membrane, but the property of rejection of the modified ultrafiltration membrane decreases greatly. The results also show that the contact angle of the salt modified PVA-CA blend UF membrane decreases but the swelling in water increases with the increment of the mass fraction of alkali metal salts. Furthermore, the NaCl modified PVA-CA blend membrane has a slightly lower swelling and a little smaller contact angle of water than the KCl modified PVA-CA blend membrane does when the mass fraction of salts is the same.

  16. Low-polarity electrolytes on the base of crown ether complexes with alkali metal ions

    International Nuclear Information System (INIS)

    New low-polar electrolytes on the basis of 15-crown-5 complexes with alkali metal (lithium, sodium) ions in solvent characterized by low dielectrical permittivity: benzene, toluene, ethylene glycol dimethyl ether, tetrahydrofuran and methylene chloride, characterized by specific electrical permittivity equal to 10-5-10-2 Ohm-1·cm-1, are suggested and studied. 15 refs., 2 figs.,

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    Science.gov (United States)

    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

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

    KAUST Repository

    Zhang, J.-Y.

    2012-12-03

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

  20. Mechanism of alkali metal insertion into TiO2 polymorphs

    Czech Academy of Sciences Publication Activity Database

    Zukalová, Markéta; Lásková, Barbora; Kavan, Ladislav

    Toulouse: Phantoms Foundation, 2015. s. 139-139. [TNT2015. Trends in Nanotechnology /16./. 07.09.2015-11.09.2015, Toulouse] R&D Projects: GA ČR GA13-07724S; GA ČR(CZ) GA15-06511S Institutional support: RVO:61388955 Keywords : TiO2 * alkali metal insertion Subject RIV: CG - Electrochemistry

  1. Alkali metal insertion into TiO2 polymorphs for battery applications

    Czech Academy of Sciences Publication Activity Database

    Zukalová, Markéta; Pitňa Lásková, Barbora; Kavan, Ladislav

    Dubai: EMN Dubai, 2016. s. 13-14. [EMN Dubai Meeting. Energy Materials Nanotechnology . 01.04.2016-04.04.2016, Dubai] R&D Projects: GA ČR GA15-06511S Institutional support: RVO:61388955 Keywords : TiO2 polymorphs * alkali metal insertion * LTO Subject RIV: CG - Electrochemistry

  2. Liquid metal cooled reactor - alkali metal thermoelectric space power system concept for multi megawatt applications

    International Nuclear Information System (INIS)

    A number of Strategic Defense Initiative missions require space power systems with lifetime on the order of 7 to 10 years and systems with reliabilities greater than 0.95. In addition, power source system mass must be as low as possible, consistent with existing and projected launch capabilities. For steady state power sources greater than tens of kilowatts, nuclear reactor systems would yield the lowest system mass. Among potential power conversion systems, Alkali Metal Thermoelectric (AMTEC) is highly attractive from a number of standpoints: it has the highest conversion efficiencies among the different types of static energy conversion systems at moderate operating temperatures that are reasonably high so that waste heat rejection can be carried out with relatively low system mass

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

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

  5. Adsorption of Alkali, Alkaline Earth and Transition Metal Atoms on Silicene

    OpenAIRE

    Sahin, Hasan; Peeters, Francois M.

    2013-01-01

    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, workfuncti...

  6. Electrohydrodynamic emission of positive and negative ions from alkali-metal halide melts

    International Nuclear Information System (INIS)

    The characteristics of electrohydrodynamic (EHD) emission of positive and negative ions from melts of alkali-metal metals are presented. The angular current density is 3-4 μA/sr with emission currents of 0.1-0.5 μA. The salt EHD sources which have been developed yield stable currents of K+, Rb+, Cs+, F-, Cl-, and I- ions for several tens of hours. 10 refs., 4 figs., 1 tab

  7. Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

    Institute of Scientific and Technical Information of China (English)

    Yan Cao; Yunxia Zhao; Fujiao Song; Qin Zhong

    2014-01-01

    Metal-organic frameworks (MOFs) have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-1(also named Cu-BTC or MOF-199) was chemically reduced by doping it with alkali metals (Li, Na and K) and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction (XRD), thermo-gravimetric analysis (TGA) and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li+, Na+ and K+, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11%increase in adsorption capacity at 298 K and 18 bar as compared with HKUST-1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    In aqueous solutions, the alkali metals ions, Li+, Na+, K+, Rb+ and Cs+ are known to be associated with a number of H2O molecules. Traditionally, a distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and...... a secondary (or outer) solvation shell, consisting of all other water molecules whose properties are still influenced significantly by the cation. Knowing the hydration number is important when considering, for instance, the transport of Na+ and K+ in biological cell membranes, since their different...... necessarily define the same hydration shell. This work presents a systematic study of one special variant of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS-). The technique of...

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

    Science.gov (United States)

    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

  10. Intra-zoned luminescence in alkali earth metal carbonates

    International Nuclear Information System (INIS)

    Full text: The fundamental plasma luminescence of wide band alkali halide crystals has been found out by Vaisburd et al. This broadband luminescence with very short duration of attenuation (∼10-12 s) arises at an irradiations of crystals with electronic beam powerful pulses of nanosecond duration. It is related to radiating 'hot' electrons and holes in a conductivity zone and in a valent zone, accordingly and in later time began to refer to as an intra-zoned luminescence. The data set on revealing features of display of an intra-zoned luminescence in different classes of crystals now proceeds. We investigated a fast luminescence at excitation with pulse electrons (3 nanoseconds) in crystals CaCO3, SrCO3, BaCO3 and MgCO3. In spectra all investigated carbonates it is possible to allocate two areas: area concerning high intensity of a fast luminescence (from 2 eV down 3 eV) and area of low intensity (is higher 4 eV) with slow recession at increase in photon energy. Thus it is typical, that in area concerning high intensity at rise in temperature from 80 up to 300 K a sample intensity of luminescence falls down, whereas in area is higher 5 eV with rise in temperature of a sample increase of intensity is observed. This broadband fast (is shorter than the time sanction of the equipment) should be connected a luminescence poorly dependent on temperature and a modular status of a sample with intra zoned transitions This luminescence reaches from 2 eV down to 7 eV but as for carbonates while is absent the reliable data on structure of a valent zone, division of an intra-zoned luminescence into electronic and hole components is not obviously possible on the basis of spectra of a fast luminescence. The nature of other luminescence processes arising at excitation with pulse electrons is discussed

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

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

    CERN Document Server

    Lutz, Jesse J

    2013-01-01

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH$_{3}X$ ($X$ = F, Cl, Br, I) and alkali-metal atoms $A$ ($A$ = Li, Na, K, Rb) using high-level {\\it 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, ${\\rm CH}_{3}X+A\\rightarrow{\\rm CH}_{3}+AX$. 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.

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

    CERN Multimedia

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, K., E-mail: kazuhiro-matsuda@scphys.kyoto-u.ac.jp; Fukumaru, T.; Kimura, K.; Yao, M. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Tamura, K. [Graduate School of Engineering, Kyoto University, Kyoto 606-8502 (Japan); Katoh, M. [A.L.M.T. Corp., Iwasekoshi-Machi 2, Toyama 931-8543 (Japan); Kajihara, Y.; Inui, M. [Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

    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.

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

    International Nuclear Information System (INIS)

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH3X (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, CH3X + A → CH3 + 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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mousazadeh, M.H., E-mail: mmousazadeh@aeoi.org.ir [Department of Chemistry, Nuclear Science Research School, Nuclear Science and Technology Research Institute (NSTRI), End of North-Karegar Str., 11365-3486 Tehran (Iran, Islamic Republic of); Faramarzi, E. [Department of Physical Chemistry, School of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Maleki, Z. [Department of Chemistry, Nuclear Science Research School, Nuclear Science and Technology Research Institute (NSTRI), End of North-Karegar Str., 11365-3486 Tehran (Iran, Islamic Republic of)

    2010-11-20

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

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

    International Nuclear Information System (INIS)

    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

  19. The 3-Dimensional q-Deformed Harmonic Oscillator and Magic Numbers of Alkali Metal Clusters

    CERN Document Server

    Bonatsos, Dennis; Raychev, P P; Roussev, R P; Terziev, P A; Bonatsos, Dennis

    1999-01-01

    Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3) > SOq(3) symmetry are compared to experimental data for alkali metal clusters, as well as to theoretical predictions of jellium models, Woods--Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. The 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry of systems of alkali metal clusters.

  20. Conductometric determination of dissociation constants of alkali metal monopyrocatechinborates in alcohols

    International Nuclear Information System (INIS)

    Dissociation constants of alkali metal monopyrocatechinborates of Me[(C6H4O2)B(OH)2]xnH2O (Me = Na+, Li+) composition are determined using conductometric method based on equivalent electric conductivity values, in methanol and ethanol at 25 deg C. Dissociation constants of weak electrolytes are calculated by the Fuoss-Kraus method. Conditions of Valden raw action are determined which connects concentrations with permittivity of medium

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

    International Nuclear Information System (INIS)

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

  2. Characterization of the conduction properties of alkali metal ion conducting solid electrolytes using thermoelectric measurements

    OpenAIRE

    Gautam, Devendraprakash

    2006-01-01

    Under certain circumstances the electronic conductivity of the solid electrolyte may play a pivotal role for the behaviour of a solid state galvanic cell. Quantitatively, the extent of the electronic conductivity is expressed by the electronic conduction parameters, a and a, that denote the alkali metal activities at which the n and p-type electronic conductivities, respectively, of the electrolyte are equal to its ionic conductivity. Previous findings demonstrated the existen...

  3. Effect of radiation trapping on the polarization of an optically pumped alkali-metal vapor

    International Nuclear Information System (INIS)

    Calculations are presented of the limitations imposed by radiation trapping on the electron spin polarization produced in an alkali-metal vapor by optical pumping in a large magnetic field. It is found that electron spin polarizations of 90% are possible with Na densities up to 1019 atoms/m3 and ground-level relaxation times of 150 μs in a large magnetic field using a cylindrical geometry of radius 7.5 x 10-3 m

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

    OpenAIRE

    Ashraf Yehia El-Naggar

    2013-01-01

    Modification of the precipitated silica gel was done by treatment with alkali metal (NaCl) before and after calcination. The silica surfaces before and after modification were confirmed by infrared spectroscopy in order to observe the strength and abundance of the acidic surface OH group bands which play an important role in the adsorption properties of polar and nonpolar solutes. The surface-modified silica gels were tested as GC solid stationary phases in terms of the separation efficiency ...

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

    CERN Document Server

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

    2001-01-01

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

  6. A hexagonal structure for alkali-metal doped poly (p-phenylene)

    Science.gov (United States)

    Murthy, N. S.; Baughman, R. H.; Shacklette, L. W.; Fark, H.; Fink, J.

    1991-05-01

    An hexagonal structure (space group p overline62m, a = 8.6 Å) is proposed for sodium-doped poly(p-phenylene), PPP. The diffraction pattern calculated using only one freely adjustable parameter (the distance between the alkali-metal column and the polymer backbone) is in good agreement with the observed electron diffraction patterns. A similar structure ( a = 9.2 Å) is also suggested by diffraction data for potassium-doped PPP. This hexagonal structure is analogous to that reported for sodium-doped poly(p-phenylene vinylene), lithium-doped polyacetylene, and sodium-doped polyacetylene. The three chain per column arrangement provides a fundamental structural motif which maximizes the coordination of the negatively charged carbon atoms with both the alkali metal ions and the hydrogens, and maximizes interchain, intercolumn, and hydrogen to alkali-metal separations. The size of the dopant-ion relative to the cross-sectional dimensions of the host polymer determines whether the dopant-ion columns are formed in triangular (three chain per column) or tetragonal (four chain per column) channels.

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

    Science.gov (United States)

    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.

  8. Interpretation of X-ray diffraction from liquid alkali metals

    International Nuclear Information System (INIS)

    It is known that, near freezing, the peaks in the liquid structure factors of Na and K reflect the ordering of a body-centred cubic lattice. Therefore, we have considered the modifications introduced into the electron distribution of a body-centred cubic, nearly-free electron, metal by destruction of the long-range order. Use of the Wannier representation, as has been pointed out by Matthai et al. leads naturally in a metal to bond charges at the centres of near-neighbour, next-near neighbour, etc. bonds. Because of the absence of long-range order in the nuclei of liquid Na and K, it is argued that only near-neighbour and perhaps next-near neighbour bond charges remain meaningful. Thus, whereas in crystalline Na and K, the totality of the bond charge distributions, including however many longer and longer bonds, adds up to an almost constant electron density of the valence electrons, in the liquid the local angularity of the electron density is significant. We find then that a model which can explain the observed reflections, which are characteristic of a face-centred-cubic lattice, can be built up by: (a) using local sp3 type bonding charges, with Pauling resonance invoked between occupied and unoccupied bonds; (b) assuming, once local electron co-ordination characteristic of such bonds is formed, Wigner-type lattice ordering can propagate the face-centred lattice over distances of 30 to 40 A. The differences to be expected between nearly-free electron metals and tight-binding metals in the liquid state are finally stressed. (author)

  9. N-alkyl pyrrolidone ether podands as versatile alkali metal ion chelants.

    Science.gov (United States)

    Perrin, Andrea; Myers, Dominic; Fucke, Katharina; Musa, Osama M; Steed, Jonathan W

    2014-02-28

    This work explores the coordination chemistry of a bis(pyrrolidone) ether ligand. Pyrrolidones are commercially important functional groups because of the high polarity and hence high hydrophilicity and surface affinity. An array of alkali metal ion complexes of a podand bearing two pendant pyrrolidone functionalities, namely 1-{2-[2-(2-oxo-pyrrolid-1-yl)-ethoxy]-ethyl}-pyrrolid-2-one (1) are reported. Reaction of this ligand with sodium hexafluorophosphate gives two discrete species of formulae [Na(1)2]PF6 (3) and [Na3(H2O)2(μ-1)2](PF6)3 (4), and a coordination polymer {[Na3(μ3-1)3(μ2-1)](PF6)3}n (5). The same reaction in methanol gives a 1 : 1 complex, namely [Na2(μ-1)2(MeOH)2](PF6)2 (6). Use of tetraphenyl borate as a less coordinating counter ion gives [Na2(1)2(H2O)4](BPh4)2 (7) and [Na2(1)4](BPh4)2 (8). Two potassium complexes have also been isolated, a monomer [K(1)2]PF6 (9) and a cyclic tetramer [K4(μ4-H2O)2(μ-1)4](PF6)4 (10). The structures illustrate the highly polar nature of the amide carbonyl moiety within bis(pyrrolidone) ethers with longer interactions to the ether oxygen atom. The zinc complex is also reported and {[ZnCl2(μ-1)]}n (11) exhibits bonding only to the carbonyl moieties. The ether oxygen atom is not necessary for Na(+) complexation as exemplified by the structure of the sodium complex of the analogue 1,3-bis(pyrrolid-2-on-1-yl)butane (2). Reaction of compound 1 with lithium salts results in isolation of the protonated ligand. PMID:24336897

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Christensen, Ole Bøssing; Jacobsen, Karsten Wedel

    1992-01-01

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

  12. Heavy main-group iodometallates hybridized by alkali metal via 1,10-Phenanthroline-5,6-dione

    Indian Academy of Sciences (India)

    Mengfan Yin; Gengxing Cai; Peng Wang; Xihui Chao; Jibo Liu; Haohong Li; Zhirong Chen

    2015-09-01

    Alkali metals were introduced into heavy main-group iodometallates to get two new IA/IVAheterometallic frameworks [PbI3K(pdon)(H2O)2] (1) and {[Pb3I9K2(pdon)2(H3O)]·H2O} (2) (pdon=1,10-phenanthroline-5,6-dione), which were obtained as single phases by hydrothermal method at different pH values. Compounds 1 and 2 are three-dimensional heterometallic frameworks constructed from the linkage of pdon ligand between iodometallate chains and potassium oxides/iodide clusters. Specially, these two heterometallic frameworks exhibit broadened absorption bands at 700 and 750 nm compared with those of bulk PbI2 and pdon ligand. The band gap of 2 is wider than that of 1, which is due to the absence of · · · interaction in 2. Their thermal stabilities are also discussed.

  13. ELECTROHYDRAULIC LEACHING OF ALKALI METALS FROM ZINNWALDITE MICA

    Czech Academy of Sciences Publication Activity Database

    Faltus, M.; Babický, Václav; Botula, J.; Hong Vu, N.; Člupek, Martin

    Bratislava: Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava (Slovakia); Society for Plasma Research and Applications in cooperation with Library and Publishing Centre CU, Bratislava, Slovakia, 2015 - (Papp, P.; Országh, J.; Moravský, L.; Ribar, A.; Matejčík, Š.), s. 234-239 ISBN 978-80-8147-027-1. [Symposium on Application of Plasma Processes COST TD1208 Workshop on Application of Gaseous Plasma with Liquids: SAPP XX /20./. Tatranská Lomnica (SK), 17.01.2015-22.01.2015] R&D Projects: GA MŠk(CZ) LD14080 Grant ostatní: European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : electrical discharge in liquid * leaching of metals Subject RIV: BL - Plasma and Gas Discharge Physics http://is.muni.cz/repo/1219429/SAPP_XX_2015.pdf

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

    International Nuclear Information System (INIS)

    The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C60 and C70 was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C60 and C70 decrease distinctly and vary linearly with the electronegativity of the alkali metal elements, and the positions where the alkali atoms are adsorbed considerably influence the work functions. On the contrary, a vacancy defect elevates the work functions of the fullerenes C60 and C70. The variation in the work functions rests with variation in Fermi level (which are attributed to charge transfer) and variation in vacuum levels (which are attributed to the induced dipole moments). Moreover, alkali-metal adsorption can also improve the electric conductivity of a fullerene mixture of C60 and C70.

  15. Platinum-tungsten electrodes for the alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    Co-sputtered platinum-tungsten AMTEC electrodes have shown high power densities (--0.5 X/cm/sup 2/) after operation at --1180 K for periods up to 93 hours. After a brief period (--20 hours) of power density decline from initial values as high as 0.7 W/cm/sup 2/, power is constant or increases slowly with time. Electrodes before and after AMTEC operation have low porosity, suggesting that mass transport does not depend solely on gas-phase diffusion. Model system studies have included synthesis of a platinum-sodium compound, Pt/sub x/Na; determination of the temperature dependence of the open circuit potential of a test cell Na/sub iota//sodium beta''-alumina/Pt/sub x/Na, Pt; and study of the properties of pure platinum electrodes. These studies show that Pt/sub x/Na is thermodynamically stable up to high temperatures (>900K), but is not generally stable at the low sodium activities calculated for AMTEC electrodes under typical operating conditions. Surface diffusion enhanced transport is suggested by these results

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...... metal atom (M2) plus two to five (BH4)− groups, i.e., M1M2(BH4)2–5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with...

  17. Structure and bonding in metal-rich compounds: pnictides, chalcides and halides

    International Nuclear Information System (INIS)

    The subject is reviewed under the following headings: introduction (compounds included in the review; purpose of the review); MX compounds with M = transition metal and X = O,N,S or P; sulfides and selenides of the transition metals; transition-metal phosphides; alkali oxides; transition-metal oxides and nitrides with X/M < 1; metal-rich halides; conclusion. The references number 238. Compounds of the following principal elements of nuclear interest are included in the tables and text: Am, Ce, Cs, Eu, Gd, Hf, La, Mo, Np, Nb, Pu, Pr, Pa, Re, Ru, Sc, Ta, Tb, Th, W, U, V, Y, Zr. The information in the tables is presented under: structure type, space group, lattice parameters and remarks. (U.K.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  19. Detection of Metallic Compounds in Rocket Plumes

    Science.gov (United States)

    Rogers, Chris; Dunn, Dr. Robert

    1998-04-01

    Recent experiments using metal mixed in hydroxyl-terminated polybutadiene (HTPB) fuel grains in small hybrid rocket indicates ion detectors may be effective in detection of metallic compounds in rocket plumes. We wanted to ascertain the extent to which the presence of metallic compounds in rocket plumes could be detected using ion probes and Gaussian rings. Charges that collide with or pass near the intruding probe are detected. Gaussian rings, short insulated cylindrical Gaussian surfaces, enclose the plume without intruding into the plume. Charges in the plume are detected by currents they induce in the cylinder.

  20. Polymers contamination by heavy metal compounds

    Directory of Open Access Journals (Sweden)

    Jovanić Saša

    2002-01-01

    Full Text Available The contamination of important synthetic (surface unmodified polymers by various heavy metal compounds (such as copper, manganese and lead in aqueous medium was investigated in this study. The influence of the pH of the aqueous medium, temperature and metal type on contamination was investigated during a 10 day period. It was found that increasing pH contributed to higher polymer contamination (at higher pH 100 times for copper and up to 400 times for lead, as well as contact with easily penetrable substances. Increasing temperature decreased contamination by the metal compound for PELD and PET which was not the case for PEHD and PR.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-08-01

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

  2. Intercalation of heavy alkali metals (K, Rb and Cs) in the bundles of single wall nanotubes

    Science.gov (United States)

    Duclaux, L.; Méténier, K.; Lauginie, P.; Salvetat, J. P.; Bonnamy, S.; Beguin, F.

    2000-11-01

    The electric-arc discharge carbon deposits (collaret) containing Single Wall Carbon Nanotubes (SWNTs) were heat treated at 1600 °C during 2 days under N2 flow in order to eliminate the Ni catalyst by sublimation, without modifications of the SWNTs ropes. Sorting this deposit by gravity enabled to obtain in the coarsest particles higher amount of SWNTs ropes than in other particle sizes. The coarser particles of the carbon deposits were reacted with the alkali metals vapor giving intercalated samples with a MC8 composition. The intercalation led to an expansion of the 2D lattice of the SWNTs so that the alkali metals were intercalated in between the tubes within the bundles. Disordered lattices were observed after intercalation of Rb and Cs. The simulations of the X-ray diffractograms of SWNTs reacted with K, gave the best fit for three K ions occupying the inter-tubes triangular cavities. The investigations by EPR, and 13C NMR, showed that doped carbon deposits are metallic.

  3. Thermodynamics and structure of liquid alkali metals from the charged-hard-sphere reference fluid

    International Nuclear Information System (INIS)

    The evaluation of thermodynamic properties of liquid alkali metals is re-examined in the approach based on the Gibbs-Bogoliubov inequality and using the fluid of charged hard spheres in the mean spherical approximation as reference system, with a view to achieving consistency with the liquid structure factor. The perturbative variational calculation of the Helmholtz free energy is based on an ab initio and highly reliable nonlocal pseudopotential. Only limited improvement is found in the calculated thermodynamic functions, even when full advantage is taken of the two variational parameters inherent in this approach. The role of thermodynamic self-consistency between the equations of state of the reference fluid derived from the routes of the internal energy and of the virial theorem is then discussed, using previous results by Hoye and Stell. An approximate evaluation of the corresponding contribution to the free energy of liquid alkali metals yields appreciable improvements in both the thermodynamic functions and the liquid structure factor. It thus appears that an accurate treatment of thermodynamic self-consistency in the charged-hard-sphere system may help to resolve some of the difficulties that are commonly met in the evaluation of thermodynamic and structural properties of liquid metals. (author). 55 refs, 4 figs, 4 tabs

  4. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

  5. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    OpenAIRE

    Martínez, S.; Acción, F.; Puertas, F.

    1992-01-01

    Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide), employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium) allowed us to determine the Lambe...

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

    Indian Academy of Sciences (India)

    Arup Banerjee; Manoj K Harbola

    2006-02-01

    In this paper we employ the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waals coefficients 6 and 8 of alkali metal clusters of various sizes including very large clusters. Such calculations become computationally very demanding in the orbital-based Kohn-Sham formalism, but are quite simple in the hydrodynamic approach. We show that for interactions between the clusters of the same sizes, 6 and 8 scale as the sixth and the eighth power of the cluster radius, respectively, and approach their classically predicted values for the large size clusters.

  7. Conductimetric determination of dissociation constants of alkali metal (bis)pyrocatechol borates in alcohols

    International Nuclear Information System (INIS)

    Dissociation constants of dipyrocatechinborates of the alkali metals of the Me[C6H4O2)2B] composition, where M - Na, K, Rb, Cs in the methanol and ethanol medium at 25 deg C, are determined through conductometric method on the basis of values of equiva lent electroconductivities. The dissociation constants of low power electrolytes are calculated through the Fuoss-Kraus method. The performance conditions of the Valden rule, binding the substances concentrations with dielectric permittivity of the medium, are identified

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

    International Nuclear Information System (INIS)

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

  9. A study of the chemistry of alkali metals in the upper atmosphere

    Science.gov (United States)

    Silver, J. A.; Kolb, C. E.

    1985-01-01

    The reactions of metallic species introduced into the atmosphere by meteor ablation may play a significant role in mesospheric and stratospheric chemistry. During this second year of a three year program to investigate these phenomena, we have completed measurements for the reactions of atomic sodium with ozone, and of NaO with ozone. Preliminary measurements of the rate constant for the reaction of NaO2 + HCl have been done, as well as an initial photodissociation cross section determination for NaCl at 193 nm. We have also begun to investigate the means by which neutral gas phase alkali species may be removed from the mesosphere and stratosphere.

  10. Surface tension of molten alkali metal halides as a function of ion sizes

    International Nuclear Information System (INIS)

    The analysis of the experimental data on the surface tension of the liquid/vapor interphase boundary of the molten alkali metal halides MX (M Li-Cs, X = F-I) near the melting temperature, accounting for the cation and anion dimensional differences, is presented. The main attention is focused at the manifestation of the effects of the interphase boundary of the effects of the interphase boundary thickness and twofold electric layer. It is shown, that the experimental data on the whole MX series may be represented in the form of the electrocapillary curve on the graph of the surface tension dependence on the degree of the halides dimensional asymmetry

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

    OpenAIRE

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

    2014-01-01

    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–N...

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

    International Nuclear Information System (INIS)

    High scintillation efficiency of Eu-doped LiSrAlF6 (LiSAF) and LiCaAlF6 (LiCAF) codoped with alkali metal ions has been reported in our recent studies. Thus in this paper, we demonstrated the scintillation properties of 1% Ce-doped LiSAF crystals with 1% alkali metal ions co-doping to increase the light yield and understand the scintillation mechanism. The crystals showed intense emission band corresponding to the 5d-4f transition of Ce3+, and their light yields under thermal neutron excitation were higher than that of the Ce only doped crystal. Especially, the light yield of Ce–Na co-doped crystal exceeded about two times that of Ce only doped one. -- Highlights: ► Ce-doped and alkali metal co-doped LiSAF crystals were grown by μ-PD method. ► Alkali metal co-doped crystals showed higher light yield than Ce only doped crystal. ► Decay time of alkali metal co-doped LiSAF were longer than that of Ce only doped one

  13. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    Directory of Open Access Journals (Sweden)

    Martínez, S.

    1992-09-01

    Full Text Available Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide, employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium allowed us to determine the Lambert-Beer law slopes for each compound. These values are differents (bearing in mind experimental random errors, so we have could to affirm the nonexistence of solid solution between the nitrate and the alkaline halide médium. The L-B law obtained by us can be used for the Identification differentiation and quantitative analysis of these nitrates in solid phase, even if they are present in a very low concentration.

    Se ha realizado la asignación de los espectros infrarrojo (IR de los nitratos alcalinos, sódico y potásico, y de los alcalinotérreos, magnésico y cálcico, en estado sólido. Se ha visto la influencia del medio dispersante (haluro alcalino, utilizado en la preparación de la muestra sólida. El estudio cuantitativo de la absorbencia de la banda a 1.387 cm-1 (presente en los espectros IR de los cuatro nitratos en medio KBr permite determinar las pendientes de la Ley de Lambert-Beer Se comprueba que dichas pendientes son diferentes lo que conduce a poder afirmar que no se produce disolución sólida entre el KBr y el nitrato alcalino o alcalinotérreo. La determinación de la ley de Lambert-Beer permite la identificación y el análisis cualitativo y cuantitativo por espectroscopia IR de estos nitratos cuando están presentes en bajas concentraciones en muestras sólidas.

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

    Science.gov (United States)

    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

  15. On metal oxide solubilities in some molten alkali metal bromides at T = 973 K

    International Nuclear Information System (INIS)

    Highlights: • Solubility products of MeO oxides in KBr–NaBr and KBr–LiBr eutectics are presented. • Correlation between radius of cation entering in oxide and its solubility is found. • Melt acidity increases in CsBr − KBr → KBr − NaBr → KBr − LiBr sequence. • The common oxoacidity scale of alkali metal chlorides and bromides is constructed. - Abstract: Reactions of Me2+ cations with O2− in molten (KBr + NaBr) (0.5:0.5) and (KBr + LiBr) (0.4:0.6) mixtures at T = 973 K were studied by potentiometric titration method using Pt(O2)|ZrO2(Y2O3) indicator electrode. In the former melt, the set of cations available for investigation was wide enough (Me = Sr, Ca, Mn, Co, Ni and Pb) and the corresponding solubility product indices (pKs,MeO, molalities) were found to be (3.81 ± 0.3) (SrO), (5.00 ± 0.3) (CaO), (7.85 ± 0.3) (MnO), (8.80 ± 0.1) (CoO), (9.72 ± 0.04) (NiO) and (5.20 ± 0.3) (PbO). A correlation between pKs,MeO and the polarisation action of the metal cation by Goldschmidt (ZerMe2+-2) was obtained. The oxide solubilities on the mole fraction scale were shown to be close to those obtained in molten (KCl + NaCl) equimolar mixture. On the basis of the solubility data the oxobasicity index (primary medium effect for oxide ion) for the (KBr + NaBr) melt was estimated as pI{KBr–LiBr} = −0.24. Due to considerable oxoacidic properties of Li+ cation in the molten (KBr + LiBr) eutectic, it was possible to study only three from the above cations (Me = Mn, Co and Ni) and their pKs,MeO values were (4.36 ± 0.2), (5.19 ± 0.05) and (6.25 ± 0.03), respectively. Comparison with the corresponding data for (KBr + NaBr) equimolar mixture showed that the Li+-based melt dissolved all the studied oxides in more extent. On the basis of the data obtained, the oxobasicity index value pI{KBr−LiBr} was estimated as (3.01 ± 0.5), that was close to the similar parameter of the chloride analogue (KCl + LiCl) (3.36). The change of the constituent anion of the

  16. The effects of correlation, relativity, exchange, channels coupling and polarization in scattering of electrons by alkali-metal atoms and alkali-like ions

    International Nuclear Information System (INIS)

    The present review briefly presents the growing experimental as well as theoretical interest in recent years in the effects of correlation, relativity, exchange, channels coupling and polarization on the high precision scattering of electron by alkali-metal atoms and alkali-like ions. Many high precision experiments have been performed which need very high accurate theoretical prediction for correct interpretation and identification of different physical effects involved. Several sophisticated theoretical techniques have been developed for inclusion of the above mentioned effects which play an extremely important role in order to obtain results of high accuracy for understanding experimental observation of high precision. At present, we do not have a comprehensive and practical atomic scattering theory which accounts for all these effects on an equal footing. Future challenges and directions, in reliable electron-atom scattering calculations, have been discussed and suggested. (author). 136 refs, 16 figs

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

    DEFF Research Database (Denmark)

    Lottermoser, L.; Landemark, E.; Smilgies, D.M.; Nielsen, M.; Feidenhans'l, R. Falkenberg; Johnson, R.L.; Gierer, M.; Seitsonen, A.P.; Kleine, H.; Bludau, H.; Over, H.; Kim, S.K.; Jona, F.

    1998-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Rao, B. Narasimha; Suvarna, R. Padma

    2016-05-01

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

  20. A numerical study of spin-dependent organization of alkali-metal atomic clusters using density-functional method

    International Nuclear Information System (INIS)

    We calculate the different geometric isomers of spin clusters composed of a small number of alkali-metal atoms using the UB3LYP density-functional method. The electron density distribution of clusters changes according to the value of total spin. Steric structures as well as planar structures arise when the number of atoms increases. The lowest spin state is the most stable and Lin, Nan, Kn, Rbn, and Csn with n = 2–8 can be formed in higher spin states. In the highest spin state, the preparation of clusters depends on the kind and the number of constituent atoms. The interaction energy between alkali-metal atoms and rare-gas atoms is smaller than the binding energy of spin clusters. Consequently, it is possible to self-organize the alkali-metal-atom clusters on a non-wetting substrate coated with rare-gas atoms.

  1. Higher-order Cn dispersion coefficients for the alkali-metal atoms

    International Nuclear Information System (INIS)

    The van der Waals coefficients, from C11 through to C16 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 Cn/rn 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 C10/r10 results in a dispersion interaction that is accurate to better than 1% whenever the inter-nuclear spacing is larger than 20a0. This level of accuracy is mainly achieved due to the fortuitous cancellation between the repulsive (C11,C13,C15) and attractive (C12,C14,C16) dispersion forces

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1992-11-01

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

  3. Enthalpic Interaction for α-Amino Acid with Alkali Metal Halides in Water

    Institute of Scientific and Technical Information of China (English)

    LU,Yan(卢雁)

    2004-01-01

    The studies of the enthalpic interaction parameters, hxy, hxyy and hxxv, of alkali metal halides with glycine,α-alanine and α-aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the α-amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt's effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxy with the radius of cations is not evident. The value of hxyy will increase with the increase of the radii of the ions. As the increase of the number of carbon atoms of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α-alanine for the ions which have small size. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.

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

    Science.gov (United States)

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

    2014-12-01

    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

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

    Directory of Open Access Journals (Sweden)

    Matthias Leven

    2013-01-01

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

  6. Crossover from metal to insulator in dense lithium-rich compound CLi4.

    Science.gov (United States)

    Jin, Xilian; Chen, Xiao-Jia; Cui, Tian; Mao, Ho-kwang; Zhang, Huadi; Zhuang, Quan; Bao, Kuo; Zhou, Dawei; Liu, Bingbing; Zhou, Qiang; He, Zhi

    2016-03-01

    At room environment, all materials can be classified as insulators or metals or in-between semiconductors, by judging whether they are capable of conducting the flow of electrons. One can expect an insulator to convert into a metal and to remain in this state upon further compression, i.e., pressure-induced metallization. Some exceptions were reported recently in elementary metals such as all of the alkali metals and heavy alkaline earth metals (Ca, Sr, and Ba). Here we show that a compound of CLi4 becomes progressively less conductive and eventually insulating upon compression based on ab initio density-functional theory calculations. An unusual path with pressure is found for the phase transition from metal to semimetal, to semiconductor, and eventually to insulator. The Fermi surface filling parameter is used to describe such an antimetallization process. PMID:26884165

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

    Science.gov (United States)

    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.

  8. Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms - a new hope

    CERN Document Server

    Soldán, Pavel; Hutson, Jeremy M

    2009-01-01

    We explore the potential energy surfaces for NH molecules interacting with alkali-metal and alkaline-earth atoms using highly correlated ab-initio electronic structure calculations. The surfaces for interaction with alkali-metal atoms have deep wells dominated by covalent forces. The resulting strong anisotropies will produce strongly inelastic collisions. The surfaces for interaction with alkaline-earth atoms have shallower wells that are dominated by induction and dispersion forces. For Be and Mg the anisotropy is small compared to the rotational constant of NH, so that collisions will be relatively weakly inelastic. Be and Mg are thus promising coolants for sympathetic cooling of NH to the ultracold regime.

  9. Molecular metal-metal bonds compounds, synthesis, properties

    CERN Document Server

    Liddle, Stephen T

    2015-01-01

    Systematically covering all areas of the Periodic Table, this is a comprehensive and handy introduction to metal-metal bonding. The 15 chapters follow a uniform, coherent structure for a clear overview, allowing readers easy access to the information. The important molecules at the genesis of each area are mentioned but the focus lies principally on research published since 2005. Important topics such as synthesis, properties, structures,notable features, reactivity and examples of applications of the most important compounds in each group with metal-metal bonding throughout the periodic ta

  10. Crystal-structural study of zirconium chelates with alkali metals of composition A2[Zr(Nta)2]·xH2O (A=Li, Na, K, Rb, Cs or CH3H6)

    International Nuclear Information System (INIS)

    Some zirconium complexes with nitrile triacetate and with alkali metal in the external sphere were studied crystalostructurally. Packing of complexes and extra-sphere cations was studied. Plane or slightly corrugated anion layers of two essentially different types arranged according to the principle of trigonal and square grids represent the standard element of crystal structure. Water molecules are located both in anion and cation layers. CN and coordination polyhedron of cations are different even in case of stereotype nature of reasons of their location in the interlayer space. In Cs-, Rb- and K- compounds polyhedrons of alkali metal form specific doubled chains. These compounds are not isomorphous ones and are characterized by a specific way of water molecule location. Structure of sodium compound differs fundamentally from other ones. Ionic conductivity may be expected in crystals. 4 refs., 6 figs., 2 tabs

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

    International Nuclear Information System (INIS)

    The van der Waals coefficients, C6, C8, and C10 for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, D8 and the three-body coefficient, C9 are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution

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

    International Nuclear Information System (INIS)

    The van der Waals coefficients C6, C8, and C10 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 C6 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)

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

    Science.gov (United States)

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

    2016-08-21

    The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li(+), Na(+), K(+), Rb(+), and Cs(+). The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity. PMID:27185388

  14. Electric dipole polarizabilities at imaginary frequencies for the alkali-metal, alkaline-earth, and inert gas atoms

    CERN Document Server

    Derevianko, Andrei; Babb, James F

    2009-01-01

    The electric dipole polarizabilities evaluated at imaginary frequencies for hydrogen, the alkali-metal atoms, the alkaline earth atoms, and the inert gases are tabulated along with the resulting values of the atomic static polarizabilities, the atom-surface interaction constants, and the dispersion (or van der Waals) constants for the homonuclear and the heteronuclear diatomic combinations of the atoms.

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

    Indian Academy of Sciences (India)

    Pranab Sarkar; Anupam Sarkar; S N Roy; B Talukdar

    2003-03-01

    It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from 3Li to 37Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton profile are found to be in good agreement with the results of more detailed configuration-interaction calculations for the atom 3Li. Similar results for 11Na, 19K and 37Rb are compared with the corresponding Hartree–Fock–Roothaan values only, for want of data from other realistic calculations.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-08-01

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

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

    International Nuclear Information System (INIS)

    The coefficient of HfCl4 and ZrCl4 separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl4+HfCl4). HfCl4 and ZrCl4 are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl

  18. Secondary transformation mechanism of paramagnetic centers in irradiated alkali metal perchlorates

    International Nuclear Information System (INIS)

    The EPR method has been used to study thermal transformations of paramagnetic centres (PC) in X-ray irradiated potassium, rubidium and cesium perchlorates. Experimental data make it possible to suppose that diffusion coefficient of O- ion a rather high and this ion is freely diffused already at 262 K. Colliding with [MeClO4]+ centres it is transformed in a molecule of oxygen. Another part of O- is transformed in stable ozonide-ion at 300 K. About room temperature hole centres dissociate with formation of ClO2 radical. It is supposed that part of electron and hole centres is not stabilized but at 77 K it is transformed in stable radiolysis products. This process most effective proceeds in dislocations and on the surface of microcrystals. The suggested model of thermal transformations of primary PC in irradiated perchlorates of alkali metals explains formation of all the finite ion and paramagnetic radiolysis products

  19. Thermal characterization of an AMTEC recirculating test cell. [Alkali Metal ThermoElectric Converter

    Science.gov (United States)

    Underwood, M. L.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Bankston, C. P.

    1990-01-01

    An alkali metal thermoelectric converter (AMTEC) recirculating test cell has been operated in order to determine the magnitudes of the primary heat losses of the cell and the value of the emissivity of the condenser surface. The energy balance included radiation losses, conductive losses, and losses due to the flow of sodium into the cell. The radiative heat flux dominated the heat loss mechanism of the cell at open circuit, and the condenser emissivity was calculated to be about 0.1. It is shown that, if this emissivity can be reduced to 0.02, then parasitic losses in an AMTEC recirculating test cell operating near peak power would be less than 40 percent of the heat required by the cell. The condenser emissivity decreases with elapsed time, resulting in improved thermal performance of the cell.

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

    Science.gov (United States)

    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.

  1. Structural systematic and crystal chemistry of novel borates with REE, Pb, Sr, and alkali metals

    International Nuclear Information System (INIS)

    Crystal structures of novel borates with REE, Pb, Sr and alkali metals were analyzed using classical fundamental buildings blocks approach. It is demonstrated that hexa-, penta-, tetra-, tri- and diborates subdivisions in systematic are real families of structures with the common peculiarities. According to the symmetrical way and the degree of FBB condensation structural-generic rows exist in every of subdivisions. Mega- or polyborates subdivision is valid for the structures with the different types of simplest FBB. In all new complex borates it is possible to separate FBB of equal or different types which are presented in isolated form or are connected into chains, layers or frameworks, and to find unexpected correlation between structures. The possibility to recognize and to visualize in this approach the polarity or non-polarity of the structural units and correspondingly the polarity or nonpolarity of the structures in the whole is very important for the conclusion on structure-properties relation. (orig.)

  2. Reasons for different solubility of alkali metal chlorides in cadmium nitrate solutions

    International Nuclear Information System (INIS)

    Maximum solubility of MCl salts (M=Li, Na, K, Cs) in solutions of cadmium nitrate and perchlorate of different concentration was measured in detail for studying the reason for different solubility of alkali metal chlorides in aqueous solutions of cadmium nitrate with concentration of 0.9 and 4.1 mol/l. It is shown that in the framework of phenomenological model of the solutions concentrated solutions of salts forming several crystallohydrates can be considered as a system of mixed solvents. In this case, preferable interaction of LiCl and CsCl with the Cd(NO3)2·9H2O type solvent, while NaCl and KCl - with the Cd(NO3)2·4H2O type solvent can be mentioned

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

    Science.gov (United States)

    Patki, Gauri Dilip

    mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

  4. Polymers contamination by heavy metal compounds

    OpenAIRE

    Jovanić Saša; Stoiljković Dragoslav M.; Popović Ivanka G.

    2002-01-01

    The contamination of important synthetic (surface unmodified) polymers by various heavy metal compounds (such as copper, manganese and lead) in aqueous medium was investigated in this study. The influence of the pH of the aqueous medium, temperature and metal type on contamination was investigated during a 10 day period. It was found that increasing pH contributed to higher polymer contamination (at higher pH 100 times for copper and up to 400 times for lead), as well as contact with easily p...

  5. FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Khachai, H; Haddou, A; Rached, D; Soudini, B [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-bel-Abbes, Sidi-bel-Abbes 22000 (Algeria); Khenata, R; Amrani, B [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, Mascara 29000 (Algeria); Bouhemadou, A [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, Setif 19000 (Algeria); Reshak, Ali H [Institute of Physical Biology, South Bohemia University, Nove Hrady 373 33 (Czech Republic)], E-mail: khenata_rabah@yahoo.fr, E-mail: a_bouhemadou@yahoo.fr

    2009-03-04

    The electronic and optical properties of M{sub 2}S (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure have been calculated, using a full relativistic version of the full-potential augmented plane-wave plus local orbitals method based on density functional theory, within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism (EV-GGA) is applied so as to optimize the corresponding potential for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with the available data. Band structure, density of states, electron charge density and pressure coefficients of energy gaps are given. Results obtained for band structure using EV-GGA are larger than those with LDA and GGA. It is found that the spin-orbit coupling lifts the triple degeneracy at the {gamma} point and the double degeneracy at the X point. The analysis of the electron charge density shows that the M-S bonds have a significant ionic character. The complex dielectric functions {epsilon}{sub 2}({omega}) for alkali metal sulfides were calculated for radiation up to 30 eV and the assignment of the critical points to the band structure energy differences at various points of the Brillouin zone was made. The pressure and volume dependence of the static dielectric constant and the refractive index are calculated.

  6. FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

    International Nuclear Information System (INIS)

    The electronic and optical properties of M2S (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure have been calculated, using a full relativistic version of the full-potential augmented plane-wave plus local orbitals method based on density functional theory, within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism (EV-GGA) is applied so as to optimize the corresponding potential for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with the available data. Band structure, density of states, electron charge density and pressure coefficients of energy gaps are given. Results obtained for band structure using EV-GGA are larger than those with LDA and GGA. It is found that the spin-orbit coupling lifts the triple degeneracy at the Γ point and the double degeneracy at the X point. The analysis of the electron charge density shows that the M-S bonds have a significant ionic character. The complex dielectric functions ε2(ω) for alkali metal sulfides were calculated for radiation up to 30 eV and the assignment of the critical points to the band structure energy differences at various points of the Brillouin zone was made. The pressure and volume dependence of the static dielectric constant and the refractive index are calculated.

  7. Experience in the Design and Operation of High-Temperature Alkali Metal Systems

    International Nuclear Information System (INIS)

    Our experience with the alkali metals began in 1942, when it became necessary to manufacture potassium as an intermediate step in producing potassium superoxide and oxygen generator chemicals for use in rebreather safety equipment evaluation. Study of the alkali metals has continued to the present with measurement of the physical properties, high temperature heat transfer properties, followed by the development of liquid metal instruments and the design and reliable manufacture of components. The present operation (up to 1200°F) of two sodium systems to study the instream mechanical properties of materials for long periods of time reveals the satisfactory operation of many components and the trouble to be experienced when operation is attempted with impurities added to the sodium. Cold-trap purification of 1200°F sodium systems is sufficient for low-corrosion operation over a 2-yr period in an AISI, Type 316 stainless-steel system. The adding of new specimens always raises the oxygen level, requiring repurification of the sodium. Some carbon was removed by the cold trap when high carbon-sodium conditions prevailed, but removal is not complete enough for satisfactory operation; therefore great care should be taken in preventing the carbon contamination. Plugging indicators were a good tool for normal operation. Under high carbon conditions the initial break in the plugging indicator curve can be related to the carburization potential of the sodium. Inert gas lines in sodium systems need to be heated above the melting point of sodium to prevent plugging. However, under high oxygen-sodium conditions, solids deposit in the cover gas regions under ambient temperatures above the melting point of sodium. It is observed that the main difficulty incurred in running with high oxygen - sodium systems is the oxide plugging of small lines. In high carbon sodium systems, the failure of valve bellows by carburization causes operational difficulties. Stability of magnetic flow

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    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.

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

    Science.gov (United States)

    Chen, Yi-Hsin; Liu, Hsin-Kuan; Chang, Wen-Jung; Tzou, Der-Lii; Lii, Kwang-Hwa

    2016-04-01

    Three mixed-alkali metals uranyl silicates, Na3K3[(UO2)3(Si2O7)2]·2H2O (1), Na3Rb3[(UO2)3(Si2O7)2] (2), and Na6Rb4[(UO2)4Si12O33] (3), have been synthesized by high-temperature, high-pressure hydrothermal reactions at 550 °C and 1440 bar, and characterized by single-crystal X-ray diffraction, photoluminescence, and thermogravimetric analysis. Compound 1 and 2 are isostructural and contain layers of uranyl disilicate. The smaller cation, Na+, is located in the intralayer channels, whereas the larger cations, K+ and Rb+, and water molecule are located in the interlayer region. The absence of lattice water in 2 can be understood according to the valence-matching principle. The structure is related to that of a previously reported mixed-valence uranium(V,VI) silicate. Compound 3 adopts a 3D framework structure and contains a unique unbranched dreier fourfold silicate chain with the structural formula {uB,41∞}[3Si12O33] formed of Q2, Q3, and Q4 Si. The connectivity of the Si atoms in the Si12O3318- anion can be interpreted on the basis of Zintl-Klemm concept. Crystal data for compound 1: triclinic, P-1, a=5.7981(2) Å, b=7.5875(3) Å, c=12.8068(5) Å, α=103.593(2)°, β=102.879(2)°, γ=90.064(2)°, V=533.00(3) Å3, Z=1, R1=0.0278; compound 2: triclinic, P-1, a=5.7993(3) Å, b=7.5745(3) Å, c=12.9369(6) Å, α=78.265(2)°, β=79.137(2)°, γ=89.936(2)°, V=546.02(4) Å3, Z=1, R1=0.0287; compound 3: monoclinic, C2/m, a=23.748(1) Å, b=7.3301(3) Å, c=15.2556(7) Å, β=129.116(2)°, V=2060.4(2) Å3, Z=2, R1=0.0304.

  12. Heavy metal screening in compounds feeds

    Directory of Open Access Journals (Sweden)

    Tomas Toth

    2015-05-01

    Full Text Available Heavy metals are generally classified as basic groups of pollutants that are now a days found in different environmental compartments. This is quite a large group of contaminants, which have different characteristics, effects on the environment and sources of origin. For environment pose the greatest risks, especially heavy metals produced by anthropogenic activities that adversely affect the health and vitality of organisms and natural environmental conditions. Livestock nutrition is among the main factors which affect not only the deficiency of livestock production and quality of food of animal origin, but they are also a factor affecting the safety and wholesomeness and the animal health. Compound feeds is characterized as a mixture of two or more feed grain. Containing organic, inorganic nutrients and specifically active compound feed meet the nutritional requirements of a given kind and age category of animals. They are used mainly in the diet of pigs, poultry, but also the nutrition of cattle, sheep, horses and other animal categories. The basic ingredients are cereals in proportion of 60-70 %. The aim of this thesis was to analyze the content of hazardous elements (copper, zinc, iron, manganese, cobalt, nickel, chromium, lead, cadmium, mercury in 15 samples of compound feeds and then evaluating their content in comparison with maximum limits laid down by Regulation of the Government of the Slovak Republic and Regulation Commission (EC.

  13. DETERMINATION OF POTASH ALKALI AND METAL CONTENTS OF ASHES OBTAINED FROM PEELS OF SOME VARIETIES OF NIGERIA GROWN MUSA SPECIES

    Directory of Open Access Journals (Sweden)

    Joshua Olajiire Babayemi

    2010-05-01

    Full Text Available Potash alkali and metal contents of ashes obtained from peels of six varieties of Nigeria Musa species were investigated. The varieties of Musa species – Musa paradisiaca (plantain, Musa ‘Gross Michel’ (Igbo banana, M.sapientum L. (paranta, Musa ‘Wild Banana’ (omini, Musa ‘Red’ (sweet banana, and Musa ‘Fugamo’ (somupeke, were investigated. The moisture, dry matter, ash and alkali contents; concentration of metals in the ashes and in the contents extracted with water from the ashes; and the ratio of potassium to other metals in the ashes and in the corresponding extracts were determined. Moisture contents ranged from 80.9 to 86.7%; dry matter content, 13.3 to 19.1%; ash content, 6.3 to 12.0%; alkali content, 69.0 to 81.9% of ash and 4.7 to 9.6% of dry sample. Samples ranged between 2.60 and 720mg/kg and in the corresponding extracts, BDL to 500.49mg/kg; ratio of concentration of potassium to other metals in the samples, 0.6 to 395; and in the extracts, 0.5 to 313. Gross michel showed the highest concentration of K (750mg/kg while omini banana gave the lowest average value (112.70mg/kg.

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Thermal Decomposition of Anhydrous Alkali Metal Dodecaborates M2B12H12 (M = Li, Na, K)

    OpenAIRE

    Liqing He; Hai-Wen Li; Etsuo Akiba

    2015-01-01

    Metal dodecaborates M2/nB12H12 are regarded as the dehydrogenation intermediates of metal borohydrides M(BH4)n that are expected to be high density hydrogen storage materials. In this work, thermal decomposition processes of anhydrous alkali metal dodecaborates M2B12H12 (M = Li, Na, K) synthesized by sintering of MBH4 (M = Li, Na, K) and B10H14 have been systematically investigated in order to understand its role in the dehydrogenation of M(BH4)n. Thermal decomposition of M2B12H12 indicates m...

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

    Science.gov (United States)

    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

  17. Hartree-Fock ground-state properties for the group 1 alkali metals and the group 11 noble metals

    International Nuclear Information System (INIS)

    In order to use wavefunction-based correlation methods in solids it is necessary to have reliable Hartree-Fock results for the infinite system of interest. Therefore we performed Hartree-Fock calculations for the group 1 alkali metals (Li to Cs) and group 11 noble metals (Cu, Ag and Au). We optimized a basis set of valence-double-ζ quality for the periodic system. For the lighter atoms all-electron basis sets are applied, whereas for the heavier atoms small-core pseudopotentials with the corresponding basis sets were used to deal with the scalar-relativistic effects. We determine the cohesive energy, the lattice constant and the bulk modulus of the systems at the Hartree-Fock level. We use the counterpoise correction for the free atom to minimize the basis set superposition error occurring for finite basis sets. The effects due to the counterpoise correction not only for the cohesive energy but also for the lattice structure and bulk modulus are discussed in detail

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

    International Nuclear Information System (INIS)

    The present report describes the use of Ion chromatography (IC) methods with spectrophotometric and direct conductivity detection for the determination of transition metal elements and alkali alkaline earth metal ions in UO2 pellets. Transmet analytical column and Metrosep- cation 1-2 column were used for the separation of transition metal elements and alkali and alkaline earth metal elements respectively. Oxalic acid and mixture of pyridine 2,6-dicarboxylic acid (PDCA), Na2SO4 and NaCl were used as mobile phase for the separation of transition metal ions and monitored after post - column reaction with 4,2-pyridylazo resorcinol (PAR) at 520nm spectrophotometrically. In the determination of alkali and alkaline earth metal ions the interference of transition metals are removed by complexing them with PDCA. Mixture of tartaric acid and PDCA employed in the separation of alkali and alkaline earth metal ions and monitored on direct conductivity detector. Mobile phase composition was optimised for the base line separation. Calibration plots of Fe3+, Cu2+, Ni2+, Co2+, Cd2+, Mn2+, Li+, Na+, K+, Mg2+, Ca2+ and Sr2+ were linear over a wide dynamic range with regression coefficient better than 0.999. Detection limit of above ions were between 5-30ppb. To prevent the overloading of the cation exchange column, uranium matrix was removed from UO2 sample by solvent extraction with 30% TBP - TOPO/CCl4. Ten sintered UO2 pellets of same lot were analysed and R.S.D. ±10% was obtained. These methods were validated by analysis of ILCE standards of UO2. (author)

  19. Optical detection of sodium salts of fluoride, acetate and phosphate by a diacylhydrazine ligand by the formation of a colour alkali metal complex

    Indian Academy of Sciences (India)

    Purnandhu Bose; Ranjan Dutta; I Ravikumar; Pradyut Ghosh

    2011-11-01

    A solution of N, N'-diacylhydrazine ligand in organic solvent is potential for colourimetric detection of F−/AcO−/PO$^{3−}_{4}$ via -NH deprotonation, tautomerization and its stabilization as a colour alkali metal complex.

  20. Structure of the Alkali-metal-atom-Strontium molecular ions: towards photoassociation and formation of cold molecular ions

    OpenAIRE

    Aymar, Mireille; Guérout, Romain; Dulieu, Olivier

    2011-01-01

    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 ...

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

    Science.gov (United States)

    Hartmann, S. R.; Happer, W.

    1974-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand). PMID:26860301

  3. Synergistic solvent extraction of crown ether complexes with alkali metal picrates by neutral donor solvents

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y.

    1983-09-01

    The solvent extraction of rubidium and cesium picrates has been studied at 25/sup 0/C with mixtures of crown ether and tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) in benzene, and the adduct-formation constants in the benzene solution have been calculated. The crown ethers used in this work were 12-crown-4 (12C4), 15-crown-5 (15C5), and benzo-15-crown-5 (B15C5). The stoichiometric composition of any extracted complex under the present experimental conditions is alkali metal ion : crown ether : TBP or TOPO : picrate ion = 1 : 1 : 1 : 1. The TOPO complex is more extractable than the corresponding TBP complex. The extractability of the Rb/sup +/ complex is larger than that of the corresponding Cs/sup +/ complex. For both TBP and TOPO, the adduct-formation constant value sequences of Rb/sup +/ and Cs/sup +/ are B15C5 > 12C4 > 15C5 and 12C4 > B15C5 > 15C5, respectively. 2 figures, 1 table.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  6. Luminescence properties of alkali metal ions sensitized CaFCl:Tb3+ nanophosphors

    Institute of Scientific and Technical Information of China (English)

    林林; 林慧; 王哲哲; 郑标; 谌基兴; 徐森元; 冯卓宏; 郑志强

    2015-01-01

    A series of CaFCl:Tb3+ and CaFCl:Tb3+,A+ (A=Li, Na and K) nanophosphors were synthesized by the one-step sol-gel method, which were reported for the first time. The sample consisted of monodisperse particles, the average size of which was 37 nm. The emissions of Tb3+ ions and oxygen defects OF? were demonstrated in the CaFCl:Tb3+ samples. The former was made up of sev-eral peaks at 488, 545, 587 and 623 nm, ascribed to5D4→7FJ (J=6–3) transitions of Tb3+ ions. The latter was shown as a broad band peaked at about 450 nm. Alkali metal ions A+(A=Li, Na and K) were introduced asthe charge compensators to improve the lumines-cence of samples. The influence of charge compensators on the emissions of Tb3+ ions and oxygen defects OF? was investigated by the measurement of fluorescence spectra and luminescence decay curves. The results indicated that all the charge compensators weakened the defects emission. Furthermore, Li+ ion was the best charge compensator, because it not only reduced the defects emis-sion but also increased the emission intensity of Tb3+ significantly. Our results suggested that this nanophosphor sensitized by the charge compensator might broaden potential applications of rare-earth doped CaFCl.

  7. H- and D- production by backscattering from alkali-metal targets

    International Nuclear Information System (INIS)

    Measurements have been made of the total backscattered D- and H- yields from thick, clean targets of Cs, Rb, K, Na, and Li, bombarded with H+2, H+3, D+2, D+3 with incident energies from 0.15 to 4.0 keV/nucleus. All of the measurements were made at background pressures less than 10-9 Torr, and the alkali-metal targets were evaporated onto a cold substrate (Tapprox.77 K) in situ to assure thick, uncontaminated targets. For each target, the H- and D- yields exhibited maxima (as high as 0.08 per incident proton or deuteron) at incident energies between 0.3 and 1.4 keV/nucleus. For both hydrogen and deuterium incident at any energy, the negative-ion yield decreases in going form Cs to Li in the order given above. Also, a definite isotope effect was observed for every target used, with the H- yield peaking at a lower incident energy than the D- yield and in most cases, the maximum H- yield was higher than the maximum D- yield. Measurements of the D- yield as a function of Cs coverage were also made for D3/sup ts+/ bombarding a Ni substrate. The D- yield maximized at or near the coverage at which the surface work function reached a minimum

  8. Study of Spectral Character of Alkali Metals Using Microwave Plasma Torch Simultaneous Spectrometer

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A microwave plasma torch(MPT) simultaneous spectrometer was used to study the spectral character and the matrix effect on alkali metal ions in solution. The main parameters were optimized. The microwave forward power was 100 W. The argon flow rate that was used to sustain the Ar-MPT included the flow rate of carrier gas and the flow rate of support gas, which were 0.8 and 1.0 L/min, respectively. The HCl concentration in the solution was 0.02 mol/L. The observation height was 9.0 mm. The detection limits of Li, Na, K, Rb, and Cs were 0.0003, 0.0004, 0.009, 0.07 and2.4 mg/L, respectively, and the results obtained by the Ar-MPT were compared with those obtained by argon inductively coupled plasma(Ar-ICP) and argon microwave induced plasma(Ar-MIP). The interference effects of several matrix elements were also studied.

  9. Second virial coefficients and viscosity property of monatomic alkali-metal gases

    International Nuclear Information System (INIS)

    In this work, we have calculated the second virial coefficients B2 of monatomic lithium, sodium, and potassium gases by using the most recent 1Σg+ and 3Σu+ Rydberg-Klein-Rees interatomic potentials. We have also determined the viscosity η and thermal conductivity λ coefficients of the alkali-metal vapors as a function of the temperature T. The results we have found of the collision integrals and of the coefficients η and λ agree quite well with some available experimental data. Besides, we have investigated the variation law with temperature T of the above thermophysical quantities. For temperatures ranging from 100 K to 3,000 K, the results can be reproduced by simple formulas η(T)=ATα and λ(T)=BTα, where for T in Kelvin, η in micropoise, and λ in 10-3 W·m-1·K-1, for lithium Li:A=0.314, B=0.1398, and α=0.863; for sodium Na:A=0.624, B=0.0846, and α=0.827; for potassium K:A=0.400, B=0.0320, and α=0.883. (author)

  10. Properties of alkali metal atoms deposited on a MgO surface: a systematic experimental and theoretical study.

    Science.gov (United States)

    Finazzi, Emanuele; Di Valentin, Cristiana; Pacchioni, Gianfranco; Chiesa, Mario; Giamello, Elio; Gao, Hongjun; Lian, Jichun; Risse, Thomas; Freund, Hans-Joachim

    2008-01-01

    The adsorption of small amounts of alkali metal atoms (Li, Na, K, Rb, and Cs) on the surface of MgO powders and thin films has been studied by means of EPR spectroscopy and DFT calculations. From a comparison of the measured and computed g values and hyperfine coupling constants (hfccs), a tentative assignment of the preferred adsorption sites is proposed. All atoms bind preferentially to surface oxide anions, but the location of these anions differs as a function of the deposition temperature and alkali metal. Lithium forms relatively strong bonds with MgO and can be stabilized at low temperatures on terrace sites. Potassium interacts very weakly with MgO and is stabilized only at specific sites, such as at reverse corners where it can interact simultaneously with three surface oxygen atoms (rubidium and cesium presumably behave in the same way). Sodium forms bonds of intermediate strength and could, in principle, populate more than a single site when deposited at room temperature. In all cases, large deviations of the hfccs from the gas-phase values are observed. These reductions in the hfccs are due to polarization effects and are not connected to ionization of the alkali metal, which would lead to the formation of an adsorbed cation and a trapped electron. In this respect, hydrogen atoms behave completely differently. Under similar conditions, they form (H(+))(e(-)) pairs. The reasons for this different behavior are discussed. PMID:18381711

  11. Nano-baskets of Calix[4]-1,3-crown in Emulsion Membranes for Selective Extraction of Alkali Metal Cations

    Institute of Scientific and Technical Information of China (English)

    Bahram Mokhtari; Kobra Pourabdollah

    2013-01-01

    Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclu-sion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of diacid calix[4]-1,3-crowns-4,5 were synthesized, and their inclusion-extraction parameters were optimized including the calixcrown scaffold (4.4%, by mass) as the carrier/demulsifier, the commercial kero-sene as diluent in membrane, sulphonic acid (0.2 mol·L-1) and ammonium carbonate (0.4 mol·L-1) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 r·min-1), and initial solute concen-tration (100 mg·L-1). The selectivity of membrane over more than ten interfering cations was examined and the re-sults reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98%-99%.

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

    OpenAIRE

    Liu, Yuanyue; Merinov, Boris V.; Goddard III, William A.

    2016-01-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same...

  13. Alkali intercalation into layered compounds: UHV in-situ preparation and reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberger, A. (Hahn-Meitner-Inst., Abt. Solare Energetik, Berlin (Germany)); Jaegermann, W. (Hahn-Meitner-Inst., Abt. Solare Energetik, Berlin (Germany)); Pettenkofer, C. (Hahn-Meitner-Inst., Abt. Solare Energetik, Berlin (Germany)); Papageorgopoulos, C.A. (Dept. of Physics, Univ. of Ioannina (Greece)); Kamaratos, M. (Dept. of Physics, Univ. of Ioannina (Greece))

    1992-11-01

    Li was adsorbed at room temperature (RT) onto UHV cleaved 2H WX[sub 2] (X=S, Se) and 1T TaS[sub 2] (0001) van der Waals surfaces. On TaS[sub 2] Li is intercalated in terms of the rigid band model leading to several phase transitions of the charge density waves. On WX[sub 2]Li is intercalated for low concentrations and leads to a decomposition reaction to Li[sub 2]S and W[sup 0] for high concentrations. These experimental results and those of previously studied alkali/layered chalcogenide combinations and their reactivity are discussed in terms of thermodynamic, kinetic and electronic effects. (orig.)

  14. Formation and evolution of point defects created in alkali halogen compounds irradiated by heavy ions

    International Nuclear Information System (INIS)

    The goal of this study was to achieve a better understanding of the heavy-ion material interaction. Alkali halogen crystals were chosen since the color centers produced by heavy ions can be distinguished easier from those generated by X rays. Measurements on KI irradiated at low temperature showed that the usual process of non radiative de-excitation of self-captured exciton is not prevailing. As the main objective of this work was the exact determination of the defects created by accelerated heavy ions, an important effort was dedicated to the spectrum deconvolution. Due to the high quality of the obtained spectra the V band analyse was possible. The defect stability was found to have the same nature in all the cubical alkali halogens and depend essentially on the crystal type. The defect evolution after irradiation is related to the diffusion coefficients corresponding to each mobile species and to the crystal lattice in which they move. Based on measurements made at different temperatures a simple modeling of the recombination kinetics was proposed. This effect was found to be specific to irradiation by heavy ions. It is difficult to determine the initial processes from the fossil defects, so, the defect history must be known as the described investigation methods do not permit to establish the transient aspect of defect creation. The important role of impurities should be stressed as the third intruder in the ion/crystal configuration; it can modify significantly the final state of the irradiated crystal, as it was found in KI, for instance. The open problems underlined in this study will probably be solved by using the atomic force microscopy and diffraction or on-line Raman measurements in ISOC chamber to avoid the passage to ambient conditions of the crystals irradiated at low temperatures

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

    Science.gov (United States)

    Garber, Anne E.; Dickens, Ricky E.

    2011-01-01

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

  16. Effect of alkali metals on the interaction of O2 and CO with some transition-metal surfaces

    International Nuclear Information System (INIS)

    The interactions of O2 and CO with alkali covered Ni, Ru, and Pt are reviewed with emphasis on the author's own studies. It is shown that the presence of alkalis changes the coadsorbates adsorption rates, heats of adsorption, and dissociative propensity, the strength of the effect depending on the alkali nature and coverage. The differences for the three substrates are interpreted comparing the properties of the clean surface. A detailed analysis of the coadsorbate--modifier interactions suggests that they depend on the adsorption state of the alkali species and the coadsorbate--substrate bond strength. Evidence of the formation of patches of ''surface complexes'' coexisting with the unperturbed surface is given and discussed in terms of strong direct alkali--coadsorbate interactions

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

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

  19. Body protective compound-157 enhances alkali-burn wound healing in vivo and promotes proliferation, migration, and angiogenesis in vitro

    Directory of Open Access Journals (Sweden)

    Huang T

    2015-04-01

    Full Text Available Tonglie Huang,1,* Kuo Zhang,2,* Lijuan Sun,3 Xiaochang Xue,1 Cun Zhang,1 Zhen Shu,1 Nan Mu,1 Jintao Gu,1 Wangqian Zhang,1 Yukun Wang,1 Yingqi Zhang,1 Wei Zhang1 1State Key Laboratory of Cancer Biology, Department of Biopharmaceutics, School of Pharmacy, The Fourth Military Medical University, 2National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University, 3Department of Ophthalmology, Xijing Hospital, The Fourth Military Medical University, Xi’an, People’s Republic of China *These authors contributed equally to this work Abstract: Chemical burns take up a high proportion of burns admissions and can penetrate deep into tissues. Various reagents have been applied in the treatment of skin chemical burns; however, no optimal reagent for skin chemical burns currently exists. The present study investigated the effect of topical body protective compound (BPC-157 treatment on skin wound healing, using an alkali burn rat model. Topical treatment with BPC-157 was shown to accelerate wound closure following an alkali burn. Histological examination of skin sections with hematoxylin–eosin and Masson staining showed better granulation tissue formation, reepithelialization, dermal remodeling, and a higher extent of collagen deposition when compared to the model control group on the 18th day postwounding. BPC-157 could promote vascular endothelial growth factor expression in wounded skin tissues. Furthermore, 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide and cell cycle analysis demonstrated that BPC-157 enhanced the proliferation of human umbilical vein endothelial cells (HUVECs. Transwell assay and wound healing assay showed that BPC-157 significantly promoted migration of HUVECs. We also observed that BPC-157 upregulated the expression of VEGF-a and accelerated vascular tube formation in vitro. Moreover, further studies suggested that BPC-157 regulated the phosphorylation level of

  20. Electronic Correlations, Jahn-Teller Distortions and Mott Transition to Superconductivity in Alkali-C60 Compounds

    Directory of Open Access Journals (Sweden)

    Alloul H.

    2012-03-01

    Full Text Available The discovery in 1991 of high temperature superconductivity (SC in A3C60 compounds, where A is an alkali ion, has been rapidly ascribed to a BCS mechanism, in which the pairing is mediated by on ball optical phonon modes. While this has lead to consider that electronic correlations were not important in these compounds, further studies of various AnC60 with n=1, 2, 4 allowed to evidence that their electronic properties cannot be explained by a simple progressive band filling of the C60 six-fold degenerate t1u molecular level. This could only be ascribed to the simultaneous influence of electron correlations and Jahn-Teller Distortions (JTD of the C60 ball, which energetically favour evenly charged C60 molecules. This is underlined by the recent discovery of two expanded fulleride Cs3C60 isomeric phases which are Mott insulators at ambient pressure. Both phases undergo a pressure induced first order Mott transition to SC with a (p, T phase diagram displaying a dome shaped SC, a common situation encountered nowadays in correlated electron systems. NMR experiments allowed us to study the magnetic properties of the Mott phases and to evidence clear deviations from BCS expectations near the Mott transition. So, although SC involves an electron-phonon mechanism, the incidence of electron correlations has an importance on the electronic properties, as had been anticipated from DMFT calculations.

  1. Electronic structure of alkali metal hydrides on data of cluster calculations by LCAO MO SCF CNDO

    International Nuclear Information System (INIS)

    The results of quantum-chemical study in where by M = Li, Na, K, Rb and Cs, are presented. The calculation expresses the expected electron density distributions in hydrides on the hydrogen and metal atoms as well as the energy characteristics: M-H, M-M and compounds binding energies. The latter ones qualitatively correlate with the binding energies of LiH-CsH compounds. The calculated values for the Fermi energy and the width of the forbidden zone at the Fermi level make it possible to suppose that the ideally formed lithium hydride crystal will be characterized by the highest electrical resistance. It is established that quantum-chemical characteristics of the MH hydrides structure change nonmonotonously by transfer from Li to Cs

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

    International Nuclear Information System (INIS)

    Graphical abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. Adsorption of alkali atoms involves a charge transfer process, creating positively-charged alkali atoms and this polarizes the H2 molecules and increases their binding energy. The maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 H2 were adsorbed in molecular form. - Abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. The alkali atom adsorption takes place near the six tetragonal bridge sites available on the cage, thereby avoiding the notorious clustering problem. Adsorption of alkali atoms involves a charge transfer process, creating positively charged alkali atoms and this polarizes the H2 molecules thereby, increasing their binding energy. Li atom has been found to adsorb up to three hydrogen molecules with an average binding energy of 0.189 eV. The fully doped Li6B36N36 cluster has been found to hold up to 18 hydrogen molecules with the average binding energy of 0.146 eV. This corresponds to a gravimetric density of hydrogen storage of 3.7 wt.%. Chemisorption on the Li6B36N36 has been found to be an exothermic reaction, in which 60 hydrogen atoms chemisorbed with an average chemisorption energy of -2.13 eV. Thus, the maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 hydrogen molecules were adsorbed in molecular form.

  3. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    International Nuclear Information System (INIS)

    The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y3+ is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH4 both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A3Y(BH4)6 or c-A2LiY(BH4)6 (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH4)4 crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y3+ is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH4)4 structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH4 (A=K, Rb, Cs) contains nine compounds in total. • Y3+ forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH4)4 crystallize with structure types analogous to metal oxides. • Double-perovskites decompose and form a novel borohydride-closo-borane

  4. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    Energy Technology Data Exchange (ETDEWEB)

    Sadikin, Yolanda [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Stare, Katarina [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Schouwink, Pascal [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Brix Ley, Morten; Jensen, Torben R. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Århus C (Denmark); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Černý, Radovan, E-mail: radovan.cerny@unige.ch [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland)

    2015-05-15

    The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y{sup 3+} is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH{sub 4} both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A{sub 3}Y(BH{sub 4}){sub 6} or c-A{sub 2}LiY(BH{sub 4}){sub 6} (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH{sub 4}){sub 4} crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y{sup 3+} is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH{sub 4}){sub 4} structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH{sub 4} (A=K, Rb, Cs) contains nine compounds in total. • Y{sup 3+} forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH{sub 4}){sub 4} crystallize with

  5. Task-specific ionic liquids for solubilizing metal compounds

    OpenAIRE

    Thijs, Ben

    2007-01-01

    The main goal of this PhD thesis was to design new task-specific ionic liquids with the ability to dissolve metal compounds. Despite the large quantity of papers published on ionic liquids, not much is known about the mechanisms of dissolving metals in ionic liquids or about metal-containing ionic liquids. Additionally, many of the commercially available ionic liquids exhibit a very limited solubilizing power for metal compounds, although this is for many applications like electrodeposition a...

  6. Three Alkali-Metal-Gold-Gallium Systems. Ternary Tunnel Structures and Some Problems with Poorly Ordered Cations

    Energy Technology Data Exchange (ETDEWEB)

    Smetana, Volodymyr; Miller, Gordon J.; Corbett, John D.

    2012-06-27

    Six new intermetallic compounds have been characterized in the alkali metal (A = Na, Rb, Cs)–gold–gallium systems. Three isostructural compounds with the general composition A0.55Au2Ga2, two others of AAu3Ga2 (A = Rb, Cs), and the related Na13Au41.2Ga30.3 were synthesized via typical high-temperature reactions and their crystal structures determined by single-crystal X-ray diffraction analysis: Na0.56(9)Au2Ga2 (I, I4/mcm, a = 8.718(1) Å, c = 4.857(1) Å, Z = 4), Rb0.56(1)Au2Ga2 (II, I4/mcm, a = 8.950(1) Å, c = 4.829(1) Å, Z = 4), Cs0.54(2)Au2Ga2 (III, I4/mcm, a = 9.077(1) Å, c = 4.815(1) Å, Z = 4), RbAu3Ga2 (IV, Pnma, a = 13.384(3) Å, b = 5.577(1) Å, c = 7.017(1) Å, Z = 4), CsAu3Ga2 (V, Pnma, a = 13.511(3) Å, b = 5.614(2) Å, c = 7.146(1) Å, Z = 4), Na13Au41.2(1)Ga30.3(1) (VI, P6 mmm, a = 19.550(3) Å, c = 8.990(2) Å, Z = 2). The first three compounds (I–III) are isostructural with tetragonal K0.55Au2Ga2 and likewise contain planar eight-member Au/Ga rings that stack along c to generate tunnels and that contain varying degrees of disordered Na–Cs cations. The cation dispositions are much more clearly and reasonably defined by electron density mapping than through least-squares refinements with conventional anisotropic ellipsoids. Orthorhombic AAu3Ga2 (IV, V) are ordered ternary Rb and Cs derivatives of the SrZn5 type structure, demonstrating structural variability within the AAu3Ga2 family. All attempts to prepare an isotypic “NaAu3Ga2” were not successful, but yielded only a similar composition Na13Au41.2Ga30.3 (NaAu3.17Ga2.33) (VI) in a very different structure with two types of cation sites. Crystal orbital Hamilton population (COHP) analysis obtained from tight-binding electronic structure calculations for idealized I–IV via linear muffin-tin-orbital (LMTO) methods emphasized the major contributions of heteroatomic Au–Ga bonding to the structural stability of these compounds. The relative minima (pseudogaps) in the DOS curves for IV

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

  8. Explorations of New SHG Materials in the Alkali-Metal-Nb(5+)-Selenite System.

    Science.gov (United States)

    Cao, Xue-Li; Hu, Chun-Li; Kong, Fang; Mao, Jiang-Gao

    2015-11-16

    Standard high-temperature solid-state reactions of NaCl, Nb2O5, and SeO2 resulted in two new sodium selenites containing a second-order Jahn-Teller (SOJT) distorted Nb(5+) cation, namely, Na2Nb4O7(SeO3)4 (P1̅; 1) and NaNbO(SeO3)2 (Cmc21; 2). Compound 1 exhibits an unusual 3D [Nb4O7(SeO3)4](2-) anionic network composed of 2D [Nb4O11(SeO3)2](6-) layers which are further bridged by additional SeO3(2-) anions via corner sharing; the 2D [Nb4O11(SeO3)2](6-) layer is formed by unusual quadruple [Nb4O17](14-) niobium oxide chains of corner-sharing NbO6 octahedra being further interconnected by selenite anions via Nb-O-Se bridges. The polar compound 2 features a 1D [NbO(SeO3)2](-) anionic chain in which two neighboring Nb(5+) cations are bridged by one oxo and two selenite anions. The alignments of the polarizations from the NbO6 octahedra in 2 led to a strong SHG response of ∼7.8 × KDP (∼360 × α-SiO2), which is the largest among all phases found in metal-Nb(5+)-Se(4+)/metal-Nb(5+)-Te(4+)-O systems. Furthermore, the material is also type I phase matchable. The above experimental results are consistent with those based on DFT theoretical calculations. Thermal stabilities and optical properties for both compounds are also reported. PMID:26513233

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

    KAUST Repository

    Liang, Yin

    2014-03-24

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

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

    Science.gov (United States)

    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. PMID:27136376

  11. Estimation of alkali metal mole percent and weight of calcined solids for ICPP calcine

    International Nuclear Information System (INIS)

    An updated method is given for estimation of the weight of calcined solids and volume reduction factor for calcine, and mole percent sodium plus potassium in calcine produced from radioactive waste in a fluidized-bed calciner at the Idaho Chemical Processing Plant (ICPP). It incorporates new information on a calcine chemistry from a study by K. N. Brewer and G. F. Kessinger in which they determined the compounds formed during calcination by both high temperature thermodynamic equilibrium calculations and by analyses of pilot-plant calcines. An explanation of the assumptions made in the calculations, along with several example calculations and comparisons with the previous calculation methods are included. This method allows calculation of the heat generation rate and sodium content of the calcine, which are used to determine the suitability of the calcine for storage in the ICPP bin sets. Although this method accurately predicts the weight of calcine and mole percent Na + K for its intended purpose, the compounds predicted should only be used as a first approximation for other purposes since the calculation does not incorporate all of the compounds, such as mixed-metal oxides, which may form during calcination

  12. Cooper minima in the transitions from low-excited and Rydberg states of alkali-metal atoms

    OpenAIRE

    Beterov, I. I.; Mansell, C. W.; Yakshina, E. A.; Ryabtsev, I. I.; Tretyakov, D. B.; Entin, V. M.; MacCormick, C.; Piotrowicz, M. J.; Kowalczyk, A.; S. Bergamini

    2012-01-01

    The structure of the Cooper minima in the transition probabilities and photoionization cross-sections for low-excited and Rydberg nS, nP, nD and nF states of alkali-metal atoms has been studied using a Coulomb approximation and a quasiclassical model. The range of applicability of the quasiclassical model has been defined from comparison with available experimental and theoretical data on dipole moments, oscillator strengths, and photoionization cross-sections. A new Cooper minimum for transi...

  13. Cooper minima in the transitions from low-excited and Rydberg states of alkali-metal atoms

    CERN Document Server

    Beterov, I I; Yakshina, E A; Ryabtsev, I I; Tretyakov, D B; Entin, V M; MacCormick, C; Piotrowicz, M J; Kowalczyk, A; Bergamini, S

    2012-01-01

    The structure of the Cooper minima in the transition probabilities and photoionization cross-sections for low-excited and Rydberg nS, nP, nD and nF states of alkali-metal atoms has been studied using a Coulomb approximation and a quasiclassical model. The range of applicability of the quasiclassical model has been defined from comparison with available experimental and theoretical data on dipole moments, oscillator strengths, and photoionization cross-sections. A new Cooper minimum for transitions between rubidium Rydberg states has been found.

  14. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca2+, Li+, Na+, NH4+) at concentrations up to 25 mM. This......We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...

  15. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    International Nuclear Information System (INIS)

    We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system

  16. Nuclear Wavepacket Dynamics of Alkali Adsorbates on Metal Surfaces Studied by Time-Resolved Second Harmonic Generation

    Directory of Open Access Journals (Sweden)

    Kazuya Watanabe

    2012-01-01

    Full Text Available This paper reviews recent efforts to understand the dynamics of coherent surface vibrations of alkali atoms adsorbed on metal surfaces. Time-resolved second harmonic generation is used for the coherent excitation and detection of the nuclear wavepacket dynamics of the surface modes. The principles of the measurement and the experimental details are described. The main focus is on coverage and excitation photon energy dependences of the coherent phonon dynamics for Na-, K-, and Cs-covered Cu(111. The excitation mechanism of the coherent phonon has been revealed by the ultrafast time-domain technique and theoretical modelings.

  17. Thermophysical properties of alkali metal vapours. Part II - assessment of experimental data on thermal conductivity and viscosity

    OpenAIRE

    Fialho, Paulo; Ramires, Maria de Lurdes V.; Nieto de Castro, Carlos A.; João M. N. A. Fareleira; Mardolcar, Umesh V.

    1994-01-01

    Copyright © 1994 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Article first published online: 8 MAY 2010. An analysis of the available data on the viscosity and thermal conductivity coefficients of the alkali metal vapours is presented. The analysis is based upon theoretical calculations of the properties of the monatomic systems, described in the preceding parts I and I.A of the present paper, and making use of the kinetic theory of a binary gas reacting mixture. A summary of the measur...

  18. Collimated, single-pass atom source from a pulsed alkali metal dispenser for laser-cooling experiments

    International Nuclear Information System (INIS)

    We have developed an improved scheme for loading atoms into a magneto-optical trap (MOT) from a directed rubidium alkali metal dispenser in -10 Torr ultrahigh vacuum conditions. A current-driven dispenser was surrounded with a cold absorbing 'shroud' held at ≤0 deg. C, pumping rubidium atoms not directed into the MOT. This nearly eliminates background atoms and reduces the detrimental rise in pressure normally associated with these devices. The system can be well-described as a current-controlled, rapidly switched, two-temperature thermal beam, and was used to load a MOT with 3x108 atoms

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Science.gov (United States)

    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

  2. Structural study and properties of the alkali metal, nitrosyl, and ammonium hepta- and octafluorouranates(VI)

    International Nuclear Information System (INIS)

    The thermal decomposition of the heptafluorouranates(VI) of the alkali metals is shown to take place in two steps. The first step gives the octafluorouranates(VI) and UF6, and the decomposition rate is noticeable at temperatures above 100, 130, 150, and 2100C for the Na, K, Rb, and Cs salts, respectively. The second step for Na2UF8 yields pure NaF and UF6 above 3000C, whereas the decomposition temperatures for the K, Rb, and Cs salts are above 300, 350, and 4000C, respectively. Depending on the decomposition conditions, F2 and M2UF7(M = K, Rb, Cs) or F2, UF6, and M3UF8 are formed. The heptafluorouranates(VI) of all the cations studied, except for ammonium, were shown to exhibit dimorphism. The parameters of their cubic form were obtained and are as follows: KUF7; a = 5.22 A; RbUF7; a = 5.385 A; CsUF7; a = 5.517 A; NOUF7; a = 5.334 A; NH4UF7; a = 5.393 A; NaUF7(fccub), a = 8.511 A, Z = 4. The x-ray pattern of the low-symmetry form of CsUF7 just below the solid transition temperature (15 +- 10C) was indexed with a tetragonal cell where a = 5.50 A and c = 5.37 A. The x-ray diagrams of the low symmetry form of the other MUF7 salts were not indexed, whereas those of the octafluorouranates were indexed with orthorhombic cells. The vibrational spectra of the hepta- and octafluorouranates were found to be very dependent on the temperature, and for the same temperature on the cation size. Some trends observed in this study, like the thermal decomposition temperatures or the relative symmetries, are thought to arise from the differences in the cation--anion interaction. This interaction is stronger with smaller cations, which results in more distorted anions, less ionic U--F bonds, and paradoxically less stable complexes

  3. Similarities and differences of alkali metal chlorides applied in organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lue, Zhaoyue [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Deng, Zhenbo [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Hou, Ying [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Xu, Haisheng, E-mail: hsxu@ecust.edu.cn [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Kunshan Hisense Electronics, Co., Ltd., Kunshan, Jiangsu 215300 (China)

    2012-12-15

    The similarities and differences of alkali metal chlorides (sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl) and cesium chloride (CsCl)) applied in organic light-emitting diodes (OLEDs) are investigated. The behavior is similar for the OLEDs with these four chlorides as electron injection layer (EIL). Their maximum luminance and efficiency at 100 mA/cm{sup 2} are within the ranges of 18 550 {+-} 600 (cd/m{sup 2}) with an error of 3.23% and 4.09 {+-} 0.15 (cd/A) within an error of 3.67%, respectively. The similar performance is due to almost identical electron injection barrier for NaCl, KCl, RbCl and CsCl as EIL. Interestingly, the properties are different for devices with chlorides inserted inside tris (8-hydroxyquinoline) aluminum at the position of 20 nm away from aluminum cathode, labeled as NaCl-, KCl-, RbCl- and CsCl- devices. The relation of luminance is CsCl- > RbCl- = KCl- > NaCl-, where '>' and '=' mean 'better than' and 'the same as', respectively. And the device efficiencies are decreased from CsCl to NaCl. That is, the sort order of the efficiencies is CsCl- > RbCl- > KCl- > NaCl-. The mechanism is explained by tunneling model in terms of various energy gaps estimated by optical electronegativity of NaCl, KCl, RbCl and CsCl. - Highlights: Black-Right-Pointing-Pointer Effects of NaCl, KCl, RbCl and CsCl in organic light-emitting diodes are compared. Black-Right-Pointing-Pointer The similar performance is due to almost identical electron injection barrier. Black-Right-Pointing-Pointer The different behavior of chlorides inside Alq{sub 3} is explained by tunneling model. Black-Right-Pointing-Pointer The different behavior is attributed to various energy gaps of different chlorides. Black-Right-Pointing-Pointer The efficiency of device with chlorides inside Alq{sub 3} is decreased from CsCl to NaCl.

  4. Coordination polymers based on diiron tetrakis(dithiolato) bridged by alkali metals, electrical bistability around room temperature, and strong antiferromagnetic coupling.

    Science.gov (United States)

    Benmansour, Samia; Delgado, Esther; Gómez-García, Carlos J; Hernández, Diego; Hernández, Elisa; Martin, Avelino; Perles, Josefina; Zamora, Félix

    2015-03-01

    Coordination polymer chains have been formed by the direct reaction between HSC6H2Cl2SH and FeCl3·6H2O in the presence of an aqueous solution of the corresponding alkali-metal hydroxide (M = Li, Na, and K) or carbonate (M = Rb and Cs). The structures consist of dimeric [Fe2(SC6H2Cl2S)4](2-) entities bridged by [M2(THF)4] [M = K (1), Rb (2), and Cs (3); THF = tetrahydrofuran] or {[Na2(μ-H2O)2(THF)2] (5 and 5') units. The smaller size of the lithium atom yields an anion/cation ion-pair molecule, [Li(THF)4]2[Fe2(SC6H2Cl2S)4] (4), in which the dianionic moieties are held together by Cl···Cl interactions. Electrical characterization of these compounds shows a general semiconductor behavior in which the conductivity and activation energies are mainly determined by the M-Cl and M-S bond distances. Compounds 1 and 5' are interesting examples of bistability showing reversible transitions centered at ca. 350 and 290 K with very large hysteresis of ca. 60 and 35 K, respectively. All of these compounds exhibit intradimer strong antiferromagnetic Fe···Fe interactions. PMID:25667965

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

    International Nuclear Information System (INIS)

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

  6. Phase behaviour and thermodynamics of poly(1,4-phenylene ether sulphone) and poly(ethylene oxide)/alkali-metal salt complex blends: a thermal analysis study

    International Nuclear Information System (INIS)

    The phase behaviour and thermodynamics of poly(1,4-phenylene ether sulfone) (PES) and poly(ethylene oxide) (PEO)/alkali-metal salt complex blends were investigated by means of differential scanning calorimetry (DSC) and modulated DSC (MDSC). Experimental results show that the blend systems remain miscible after incorporating various alkali-metal salts: CF3SO3Li, CF3SO3Na and CF3SO3K. The cloud point temperature strongly depended on the Li (Na or K)/O ratio in the PES-PEO/alkali-metal salt complex blends. With increasing the Li+ (Na+ or K+)/O ratio, the phase diagram of the PES-PEO/alkali-metal salt complex blends tended to be symmetrical. When Li+/O = 0.02, the lower critical solution temperature (LCST) of the PES-PEO/CF3SO3Li complex blends was located at the 30/70 PES/PEO composition. The mixing enthalpy decreased in the PES-PEO/alkali-metal salt complex blends with increasing Li+ (Na+ or K+)/O ratio. The radius of ion has significant influence on the phase behaviour of PES/PEO blends. MDSC results showed that the change of heat capacity at the temperature of the binodal phase separation is similar to that of a melt transition in semi-crystalline polymers, which confirms the mechanism of binodal phase separation: nucleation and growth

  7. Process for forming a metal compound coating on a substrate

    International Nuclear Information System (INIS)

    This patent describes a method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon

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

    CERN Document Server

    Cohen-Adad, R

    1991-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  10. Superconductivity and electrical resistivity in alkali metal doped fullerides: Phonon mechanism

    Indian Academy of Sciences (India)

    Dinesh Varshney; A Dube; K K Choudhary; R K Singh

    2005-04-01

    We consider a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. We first study the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C60 phonons. Electronic parameter as repulsive parameter and the attractive coupling strength are obtained within the random phase approximation. Transition temperature, c, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C60 phonons as 5 K, which is much lower as compared to reported c (≈ 20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. To illustrate the usefulness of the above approach, the carbon isotope exponent and the pressure effect are also estimated. Temperature dependence of electrical resistivity is then analysed within the same model phonon spectrum. It is inferred from the two-peak model for phonon density of states that high frequency intramolecular phonon modes play a major role in pairing mechanism with possibly some contribution from alkali-C60 phonon to describe most of the superconducting and normal state properties of doped fullerides.

  11. 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

    Science.gov (United States)

    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.

  12. XPS studies and photocurrent applications of alkali-metals-doped ZnO nanoparticles under visible illumination conditions

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. PMID:27109698

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

    Science.gov (United States)

    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

  15. Long-range interactions between the alkali-metal atoms and alkaline earth ions

    CERN Document Server

    Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K

    2014-01-01

    Accurate knowledge of interaction potentials among the alkali atoms and alkaline earth ions is very useful in the studies of cold atom physics. Here we carry out theoretical studies of the long-range interactions among the Li, Na, K, and Rb alkali atoms with the Ca$^+$, Ba$^+$, Sr$^+$, and Ra$^+$ alkaline earth ions systematically which are largely motivated by their importance in a number of applications. These interactions are expressed as a power series in the inverse of the internuclear separation $R$. Both the dispersion and induction components of these interactions are determined accurately from the algebraic coefficients corresponding to each power combination in the series. Ultimately, these coefficients are expressed in terms of the electric multipole polarizabilities of the above mentioned systems which are calculated using the matrix elements obtained from a relativistic coupled-cluster method and core contributions to these quantities from the random phase approximation. We also compare our estim...

  16. Characterization of Alkali Metal Dispensers and Non-Evaporable Getter Pumps in Ultra-High Vacuum Systems for Cold Atomic Sensors

    OpenAIRE

    Scherer, David R.; Fenner, David B.; Hensley, Joel M.

    2012-01-01

    A glass ultrahigh vacuum chamber with rubidium alkali metal dispensers and non-evaporable getter pumps has been developed and used to create a cold atomic sample in a chamber that operates with only passive vacuum pumps. The ion-mass spectrum of evaporated gases from the alkali metal dispenser has been recorded as a function of dispenser current. The efficacy of the non-evaporable getter pumps in promoting and maintaining vacuum has been characterized by observation of the Rb vapor optical ab...

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

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael

    2009-07-01

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

  18. Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells

    Science.gov (United States)

    Altamura, Giovanni; Wang, Mingqing; Choy, Kwang-Leong

    2016-02-01

    Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1-xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber|buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells.

  19. Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells.

    Science.gov (United States)

    Altamura, Giovanni; Wang, Mingqing; Choy, Kwang-Leong

    2016-01-01

    Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1-xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber(|)buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells. PMID:26916212

  20. Comparisons between adsorption and diffusion of alkali, alkaline earth metal atoms on silicene and those on silicane: Insight from first-principles calculations

    Science.gov (United States)

    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.

  1. Production of metal powders and compounds, especially of refractory metals

    International Nuclear Information System (INIS)

    Since the invention of filament lamps and hard metals, powder metallurgy has increasingly been used for production of semifinished products and finished products from a multitude of metals, hard metals and composite materials. Methods have been developed by which powders can be made to measured, usually physical methods, chemical-metallurgical methods, or combined methods. Requirements on metal powders are listed as well as suitable methods of fabrication. (orig.)

  2. On-sun test results from second-generation and advanced-concepts alkali-metal pool-boiler receivers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.B.; Andraka, C.E.; Moss, T.A.; Cordeiro, P.G.; Dudley, V.E.; Rawlinson, K.S.

    1994-05-01

    Two 75-kW{sub t} alkali-metal pool-boiler solar receivers have been successfully tested at Sandia National Laboratories` National Solar Thermal Test Facility. The first one, Sandia`s `` second-generation pool-boiler receiver,`` was designed to address commercialization issues identified during post-test assessment of Sandia`s first-generation pool-boiler receiver. It was constructed from Haynes alloy 230 and contained the alkali-metal alloy NaK-78. The absorber`s wetted side had a brazed-on powder-metal coating to stabilize boiling. This receiver was evaluated for boiling stability, hot- and warm-restart behavior, and thermal efficiency. Boiling was stable under all conditions. All of the hot restarts were successful. Mild transient hot spots observed during some hot restarts were eliminated by the addition of 1/3 torr of xenon to the vapor space. All of the warm restarts were also successful. The heat-transfer crisis that damaged the first receiver did not recur. Thermal efficiency was 92.3% at 750{degrees}C with 69.6 kW{sub t} solar input. The second receiver tested, Sandia`s ``advanced-concepts receiver,`` was a replica of the first-generation receiver except that the cavities, which were electric-discharge-machined in the absorber for boiling stability, were eliminated. This step was motivated by bench-scale test results that showed that boiling stability improved with increased heated-surface area, tilt of the heated surface from vertical, and added xenon. The bench-scale results suggested that stable boiling might be possible without heated-surface modification in a 75-kW{sub t} receiver. Boiling in the advanced-concepts receiver with 1/3 torr of xenon added has been stable under all conditions, confirming the bench-scale tests.

  3. Syntheses and characterization of one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

    2015-01-15

    Three new isostructural quaternary antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) have been synthesized by using alkali metal thiosulfate flux and structurally characterized by X-ray diffraction. Their structures contain A{sup +} ions around the [Sb{sub 2}Sn{sub 3}S{sub 10}]{sup 2−} chains, which are built from SbS{sub 3} pyramids, SnS{sub 6} octahedra and SnS{sub 4} tetrahedra. Raman and Mössbauer spectroscopic measurements corroborate the oxidation states and coordination environments of Sb(III) and Sn(IV). All three compounds are wide band gap semiconductors. Potassium compound undergoes partial exchange with strontium, cadmium and lead ions. - Graphical abstract: Syntheses, crystal structure, spectroscopic and partial ion-exchange studies of new one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) are described. - Highlights: • Syntheses of new alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs). • Wide band gap semiconductors with one-dimensional structure. • Topotactic partial exchange of K{sup +} ions of K{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} with Sr{sup 2+}, Cd{sup 2+} and Pb{sup 2+} ions.

  4. Equilibrium electrode U(4)-U and redox U(4)-U(3) potentials in molten alkali metal chlorides medium

    International Nuclear Information System (INIS)

    Conditional standard electrode potentials of uranium are determined for diluted solutions of its tetrachloride in alkali metal chloride melts (LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl) when using U(4) ion activity coefficient values experimentally found by the tensimetric method. These potentials shift to the electronegative side at the temperature decrease and alkali cation radius increase rsub(Msup(+)) according to the empiric ratio E*U(4)-U= -3.06+6.87x10-4 T-(1.67-10-4T-0.44) 1/rsub(Msup(+)) +-0.01. The temperature dependences of formal conditional redox potentials of the U(4)-U(3) system for above melted chlorides are estimated. The E*U(4)-U(3) value also becomes more electronegative in the series LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl. This alternation is satisfactorily described by the empiric expression E*U(4)-U(3)= -1.74+1.74x10-4T-(0.71x10-4T-0.20) 1rsub(Msup(+)) +-0.05. The calculated values Eu*(4)-U(3) are compared with those directly measured for the NaCl-KCl equimolar mixture and 3LiCl-2KCl eutectic mixture. A satisfactory confirmity has been observed

  5. Thermal and optical properties of Nd{sup 3+} doped lead zinc borate glasses—Influence of alkali metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Sasi Kumar, M.V.; Rajesh, D.; Balakrishna, A. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Ratnakaram, Y.C., E-mail: ratnakaramsvu@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2013-04-15

    In the present investigation a new series of six different Nd{sup 3+} doped alkali and mixed alkali (Li, Na, K, Li–Na, Li–K and Na–K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd–Ofelt (J–O) theory has been applied to calculate J–O intensity parameters, Ω{sub λ} (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (A{sub T}), branching ratios (β), radiative lifetimes (τ{sub R}) and integrated absorption cross-sections (Σ) were calculated using J–O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σ{sub P}) are obtained for all the observed emission transitions.

  6. Thermal and optical properties of Nd3+ doped lead zinc borate glasses—Influence of alkali metal ions

    Science.gov (United States)

    Sasi Kumar, M. V.; Rajesh, D.; Balakrishna, A.; Ratnakaram, Y. C.

    2013-04-01

    In the present investigation a new series of six different Nd3+ doped alkali and mixed alkali (Li, Na, K, Li-Na, Li-K and Na-K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd-Ofelt (J-O) theory has been applied to calculate J-O intensity parameters, Ωλ (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (AT), branching ratios (β), radiative lifetimes (τR) and integrated absorption cross-sections (Σ) were calculated using J-O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σP) are obtained for all the observed emission transitions.

  7. Thermal and optical properties of Nd3+ doped lead zinc borate glasses—Influence of alkali metal ions

    International Nuclear Information System (INIS)

    In the present investigation a new series of six different Nd3+ doped alkali and mixed alkali (Li, Na, K, Li–Na, Li–K and Na–K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd–Ofelt (J–O) theory has been applied to calculate J–O intensity parameters, Ωλ (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (AT), branching ratios (β), radiative lifetimes (τR) and integrated absorption cross-sections (Σ) were calculated using J–O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σP) are obtained for all the observed emission transitions

  8. Identification of major metal complexing compounds in Blepharis aspera

    International Nuclear Information System (INIS)

    Verbascoside and isoverbascoside, present at 0.7% and 0.2% (w/w dryweight), were identified to be major compounds that could contribute to the metal complexation in Blepharis aspera collected in Botswana, Africa. The metallophyte B. aspera has high ability to cope with a high level of metal accumulation. The presence of metal complexing compounds and/or antioxidants can prevent oxidative reactions in lipids, proteins and DNA that take place due to the metal accumulation. On-line liquid chromatography-solid phase extraction-nuclear magnetic resonance (LC-SPE-NMR) was applied for the identification, while electrospray-mass spectrometry (ESI-MS) and UV-vis spectroscopy was used to assess whether these compounds can complex with metals. It was found that verbascoside and isoverbascoside may form complexes with nickel, iron (verbascoside only) and copper. Thus, the presence of verbascoside and isoverbascoside can explain the survival of B. aspera in mineral-rich areas

  9. Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

    Institute of Scientific and Technical Information of China (English)

    由芳田; 黄世华; 时秋峰

    2010-01-01

    The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

  10. Heavy metal screening in compounds feeds

    OpenAIRE

    Tomas Toth

    2015-01-01

    Heavy metals are generally classified as basic groups of pollutants that are now a days found in different environmental compartments. This is quite a large group of contaminants, which have different characteristics, effects on the environment and sources of origin. For environment pose the greatest risks, especially heavy metals produced by anthropogenic activities that adversely affect the health and vitality of organisms and natural environmental conditions. Livestock nutrition is among t...

  11. Superconductivity of ternary metal compounds prepared at high pressures

    CERN Document Server

    Shirotani, I

    2003-01-01

    Various ternary metal phosphides, arsenides, antimonides, silicides and germanides have been prepared at high temperatures and high pressures. These ternary metal compounds can be classified into four groups: [1] metal-rich compounds MM' sub 4 X sub 2 and [2] MM'X, [3] non-metal-rich compounds MXX' and [4] MM' sub 4 X sub 1 sub 2 (M and M' = metal element; X and X' = non-metal element). We have studied the electrical and magnetic properties of these materials at low temperatures, and found many new superconductors with the superconducting transition temperature (T sub c) of above 10 K. The metal-rich compound ZrRu sub 4 P sub 2 with a tetragonal structure showed the superconducting transition at around 11 K, and had an upper critical field (H sub c sub 2) of 12.2 tesla (T) at 0 K. Ternary equiatomic compounds ZrRuP and ZrRuSi crystallize in two modifications, a hexagonal Fe sub 2 P-type structure [h-ZrRuP(Si)] and an orthorhombic Co sub 2 P-type structure [o-ZrRuP(Si)]. Both h-ZrRuP and h-ZrRuSi have rather h...

  12. Decomplexing metallic cations from metallo-organic compounds

    OpenAIRE

    Melian, C.I.; Kapteijn F.; Moulijn, J.A.

    2006-01-01

    The invention is directed to a process for liberating metallic cations from metallo-organic compounds, said process comprising contacting an aqueous solution of the metallo-organic compound with an oxidising agent, thereby oxidising the organic component and obtaining the free cation

  13. Viscometric and thermodynamic studies of interactions in ternary solutions containing sucrose and aqueous alkali metal halides at 293.15, 303.15 and 313.15 K

    Indian Academy of Sciences (India)

    Reena Gupta; Mukhtar Singh

    2005-05-01

    Viscosities and densities of sucrose in aqueous alkali metal halide solutions of different concentrations in the temperature range 293.15 to 313.15 K have been measured. Partial molar volumes at infinite dilution ($V_{2}^{0}$) of sucrose determined from apparent molar volume ($\\phi_v$) have been utilized to estimate partial molar volumes of transfer ($V^{0}_{2,tr}$) for sucrose from water to alkali metal halide solutions. The viscosity data of alkali metal halides in purely aqueous solutions and in the presence of sucrose at different temperatures (293.15, 303.15 and 313.5 K) have been analysed by the Jones-Dole equation. The nature and magnitude of solute-solvent and solute-solute interactions have been discussed in terms of the values of limiting apparent molar volume ($\\phi^{0}_{v}$), slope ($S_{v}$) and coefficients of the Jones-Dole equation. The structuremaking and structure-breaking capacities of alkali metal halides in pure aqueous solutions and in the presence of sucrose have been ascertained from temperature dependence of $\\phi^{0}_{v}$.

  14. A new route to the syntheses of alkali metal bis(fluorosulfuryl)imides: Crystal structure of LiN(SO2F)2

    Czech Academy of Sciences Publication Activity Database

    Beran, Martin; Příhoda, J.; Žák, Z.; Černík, M.

    2006-01-01

    Roč. 25, č. 6 (2006), s. 1292-1298. ISSN 0277-5387 Institutional research plan: CEZ:AV0Z40310501 Keywords : imido-bis( sulfuric acid ) difluoride * lithium bis(fluorosulfuryl)imide * alkali metal bis(fluorosulfuryl)imides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.843, year: 2006

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

    Science.gov (United States)

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

    2016-05-01

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

  16. A stochastic optimization method based technique for finding out reaction paths in noble gas clusters perturbed by alkali metal ions

    International Nuclear Information System (INIS)

    Graphical abstract: The structure of a minimum in Ar19K+ cluster. Abstract: In this paper we explore the possibility of using stochastic optimizers, namely simulated annealing (SA) in locating critical points (global minima, local minima and first order saddle points) in Argon noble gas clusters perturbed by alkali metal ions namely sodium and potassium. The atomic interaction potential is the Lennard Jones potential. We also try to see if a continuous transformation in geometry during the search process can lead to a realization of a kind of minimum energy path (MEP) for transformation from one minimum geometry to another through a transition state (first order saddle point). We try our recipe for three sizes of clusters, namely (Ar)16M+, (Ar)19M+ and (Ar)24M+, where M+ is Na+ and K+.

  17. Thermally stimulated luminescence and lattice defects in crystals of alkali metal borate LiB3O5 (LBO)

    International Nuclear Information System (INIS)

    The recombination processes and lattice defects in crystals of alkali metal borate LiB3O5 (LBO) were studied by the means of the thermally stimulated luminescence (TL) and electron spin resonance (ESR) techniques. The glow curves, the spectra of the LBO recombination luminescence, and the angular variations of ESR-spectra of the O- center in three different planes were measured in the temperature range from 80 to 400 K. The luminescence bands were assigned to the electron (Em=4.0 eV) and hole (Em=4.2 eV) recombination processes. The model of the trapped hole center O- was proposed. The processes responsible for the formation of localised electronic excitations in LBO were discussed and compared with those taking place in other wide-gap oxides

  18. Synthesis and X-ray Characterization of Alkali Metal 2-Acyl-1,1,3,3-tetracyanopropenides.

    Science.gov (United States)

    Karpov, Sergey V; Grigor'ev, Arthur A; Kayukov, Yakov S; Karpova, Irina V; Nasakin, Oleg E; Tafeenko, Victor A

    2016-08-01

    A novel route for synthesis of 2-acyl-1,1,3,3-tetracyanopropenides (ATCN) salts in high yields and excellent purities starting from readily available methyl ketones, malononitrile, bromine, and alkali metal acetates is reported. The starting aryl(heteroaryl) methyl ketones were oxidized to the corresponding α-ketoaldehydes by new a DMSO-NaBr-H2SO4 oxidation system in yields up to 90% within a short reaction time of 8-10 min. The subsequent stages of ATCN preparation are realized in aqueous media without use of any toxic solvents, in accordance with principle 5 of "green chemistry". Lithium, sodium, potassium, rubidium, and cesium 2-benzoyl-1,1,3,3-tetracyanopropenides were characterized by X-ray diffraction analysis. These salts show a good potential for synthesis of five- and six-membered heterocycles and may serve as potentially useful ligands in coordination and supramolecular chemistry. PMID:27384963

  19. Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4.

    Directory of Open Access Journals (Sweden)

    Sonica Sondhi

    Full Text Available A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

  20. A series of new phases in the alkali metal-Nb(V)/Ta(V)-Se(IV)/Te(IV)-O systems.

    Science.gov (United States)

    Gu, Qian-Hua; Hu, Chun-Li; Zhang, Jian-Han; Mao, Jiang-Gao

    2011-03-21

    Six new phases in the alkali metal-Nb(V)/Ta(V)-Se(IV)/Te(IV)-O systems have been prepared by solid-state reactions at high-temperatures. Their structures were determined by single-crystal X-ray diffraction studies. AM(3)O(6)(QO(3))(2) (A = K, Rb, M = Nb, Ta, Q = Te; A = K, M = Nb, Q = Se) are isomorphous and their structures feature a 3D network with 1D 4- and 6-MRs tunnels along the a-axis which is composed of 2D layers of corner-sharing MO(6) octahedra bridged by QO(3) groups. The alkali metal ions are located at the above 1D tunnels of 6-MRs. The structure of Cs(3)Nb(9)O(18)(TeO(3))(2)(TeO(4))(2) features a thick Nb-Te-O layer built of corner-sharing NbO(6) octahedra, TeO(3) and TeO(4) groups. The 2D layer of the NbO(6) octahedra with 1D tunnels of 6-MRs along the c-axis are formed by 1D chains of NbO(6) chains along the c-axis and linear Nb(4)O(21) tetramers by corner-sharing. The TeO(3) and TeO(4) groups are grafted on both sides of the niobium-oxide layer via Nb-O-Te or/and Te-O-Te bridges. The caesium(i) ions are located at the above 1D tunnels of 6-MRs. TGA, UV-vis and infrared spectral measurements as well as electronic structure calculations have also been performed. PMID:21293821

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

    Science.gov (United States)

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

    2015-10-01

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

  2. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere

    Indian Academy of Sciences (India)

    Jayeeta Bhattacharjee; Ravi K Kottalanka; Harinath Adimulam; Tarun K Panda

    2014-09-01

    We report the monomeric complexes of magnesium and calcium of composition [M(THF){2-Ph2P(Se)N(CMe3)}2] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)2{Ph2P(Se)N(CMe3)}] (2) and [K(THF)Ba{Ph2P(Se)N(CMe3)}3](5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg2+ (0.72Å) and Ca2+ (0.99Å) ions form the monomeric complex, whereas the larger ions K+ (1.38Å) and Ba2+ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

  3. Elementary boron and metal-boron compounds

    International Nuclear Information System (INIS)

    Elementary boron is of interest for its peculiar and difficult bonding behaviour in solids. Due to its high oxygen affinity we find no elementary boron in nature. For the same reason it is difficult to isolate pure, elementary boron, and much confusion about 'boron crystals' has been the result of more than 100 years of research. The polymorphic forms of elementary boron and its closely related higher carbides and higher metal borides as well as the simple metal borides, B3C and BN are reported. The quantum-mechanical background responsible for structure and stoichiometry of these crystals is given. (orig.)

  4. Phase behaviour and thermodynamics of poly(1,4-phenylene ether sulphone) and poly(ethylene oxide)/alkali-metal salt complex blends: a thermal analysis study

    Energy Technology Data Exchange (ETDEWEB)

    Jin, J. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE113TU (United Kingdom); Song, M. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE113TU (United Kingdom)]. E-mail: m.song@lboro.ac.uk

    2005-02-01

    The phase behaviour and thermodynamics of poly(1,4-phenylene ether sulfone) (PES) and poly(ethylene oxide) (PEO)/alkali-metal salt complex blends were investigated by means of differential scanning calorimetry (DSC) and modulated DSC (MDSC). Experimental results show that the blend systems remain miscible after incorporating various alkali-metal salts: CF{sub 3}SO{sub 3}Li, CF{sub 3}SO{sub 3}Na and CF{sub 3}SO{sub 3}K. The cloud point temperature strongly depended on the Li (Na or K)/O ratio in the PES-PEO/alkali-metal salt complex blends. With increasing the Li{sup +} (Na{sup +} or K{sup +})/O ratio, the phase diagram of the PES-PEO/alkali-metal salt complex blends tended to be symmetrical. When Li{sup +}/O = 0.02, the lower critical solution temperature (LCST) of the PES-PEO/CF{sub 3}SO{sub 3}Li complex blends was located at the 30/70 PES/PEO composition. The mixing enthalpy decreased in the PES-PEO/alkali-metal salt complex blends with increasing Li{sup +} (Na{sup +} or K{sup +})/O ratio. The radius of ion has significant influence on the phase behaviour of PES/PEO blends. MDSC results showed that the change of heat capacity at the temperature of the binodal phase separation is similar to that of a melt transition in semi-crystalline polymers, which confirms the mechanism of binodal phase separation: nucleation and growth.

  5. Dispersion coefficients for the interactions of the alkali-metal and alkaline-earth-metal ions and inert-gas atoms with a graphene layer

    Science.gov (United States)

    Kaur, Kiranpreet; Arora, Bindiya; Sahoo, B. K.

    2015-09-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients C3 of the alkali-metal ions Li+,Na+,K+, and Rb+, the alkaline-earth-metal ions Ca+,Sr+,Ba+, and Ra+, and the inert-gas atoms He, Ne, Ar, and Kr with a graphene layer are determined precisely within the framework of the Dirac model. For these calculations, we evaluate the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at room temperature.

  6. Molecular-orbital theory for the stopping power of atoms in the low velocity regime:the case of helium in alkali metals

    OpenAIRE

    Dorado, Jose J.; Flores, F.

    1993-01-01

    A free-parameter linear-combination-of-atomic-orbitals approach is presented for analyzing the stopping power of slow ions moving in a metal. The method is applied to the case of He moving in alkali metals. Mean stopping powers for He present a good agreement with local-density-approximation calculations. Our results show important variations in the stopping power of channeled atoms with respect to their mean values.

  7. Stabilization of explosive compounds on metallic surfaces

    International Nuclear Information System (INIS)

    Full text: Previous experiments on explosives like RDX, TNT or PETN in gas phase have shown that these molecules decay easily into several fragments upon low-energy electron attachment. These unimolecular decompositions are rather time consuming (several μs) and can be quenched when the molecules are embedded in helium nano droplets. With the use of a variable temperature scanning tunneling microscope, electron induced fragmentation of explosives is investigated for molecules adsorbed on single crystal metal surfaces. (author)

  8. Application of X-ray diffraction technique for determining triclinicity of alkali-feldspar from the rare metal pegmatites of the Pandikimal Area, North Orissa, India

    International Nuclear Information System (INIS)

    The zoned rare metal pegmatites of Archaean age in the Jharsuguda district of north Orissa, eastern India, are well-known for their potentiality for Nb, Ta, and Be minerals. They also contain limited Li, Bi, Th, and U minerals. Because of the economic concentrations of the ore minerals of Nb-Ta and Be, they are being mined for recovering columbite-tantalite and beryl. In this paper, the values of triclinicity of alkali-feldspars, determined by X-ray diffraction, are presented and, based on the same data, the evolutionary history of the rare metal pegmatites is traced. The values of triclinicity range from 0.83 to 0.97 with an average of 0.92. The high values of triclinicity suggest that the investigated alkali-feldspars from the rare metal pegmatites of the Pandikimal area belong to the category of maximum microcline. It would, thus, mean that during the crystallisation of alkali-feldspar, and by implication their host rare metal pegmatites, not only was the rate of cooling slow, the temperature of crystallisation was also falling. Accordingly, it is interpreted that the rare metal pegmatites of the Pandikimal area crystallised slowly under a falling-temperature regime in deep-seated plutonic conditions. The presence of large beryl crystals in the rare metal pegmatites also supports this interpretation. (author)

  9. Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

    International Nuclear Information System (INIS)

    Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-napthyl-phenyl)-1.1′-biphenyl-4.4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq3 layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: ► Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. ► Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. ► The Improved OLED performance was attributed to the possible interfacial chemical reaction. ► Electron-only devices are fabricated to demonstrate the electron injection enhancement.

  10. Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

    Energy Technology Data Exchange (ETDEWEB)

    Zou Ye [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Deng Zhenbo, E-mail: zbdeng@bjtu.edu.cn [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Xu Denghui [Department of Mathematics and Physics, Beijing Technology and Business University, Beijing 100037 (China); Lue Zhaoyue; Yin Yuehong; Du Hailiang; Chen Zheng; Wang Yongsheng [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2012-02-15

    Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N Prime -diphenyl-N,N Prime -bis(1-napthyl-phenyl)-1.1 Prime -biphenyl-4.4 Prime -diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq{sub 3})/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq{sub 3} layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: Black-Right-Pointing-Pointer Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. Black-Right-Pointing-Pointer Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. Black-Right-Pointing-Pointer The Improved OLED performance was attributed to the possible interfacial chemical reaction. Black-Right-Pointing-Pointer Electron-only devices are fabricated to demonstrate the electron injection enhancement.

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

    Science.gov (United States)

    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.

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

    CERN Document Server

    Ginges, J S M

    2016-01-01

    We present a detailed study of the Flambaum-Ginges radiative potential method which enables the accurate inclusion of quantum electrodynamics (QED) radiative corrections in a simple manner in atoms, ions, and molecules 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 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 th...

  13. Van der Waals density functional study of the energetics of alkali metal intercalation in graphite

    OpenAIRE

    Wang, Zhaohui; Selbach, Sverre Magnus; Grande, Tor

    2014-01-01

    We report on the energetics of intercalation of lithium, sodium and potassium in graphite by density functional theory using recently developed van der Waals (vdW) density functionals. First stage intercalation compounds are well described by conventional functionals like GGA, but van der Waals functionals are crucial for higher stage intercalation compounds and graphite, where van der Waals interactions are important. The vdW-optPBE functional gave the best agreement with reported structure ...

  14. Complexing of antimony(3) fluoride with rare alkali metal fluorides in formic acid

    International Nuclear Information System (INIS)

    Using the method of isothermal solubility with the establishment of solid phase compositions according to ''residue method'' the systems HCOOH-SbF3-RbF3 and HCOOH-SbF3-CsF are studied at 15 deg C. The existence of complex compounds of different compositions is established. The individual character of the compounds prepared is confirmed by the data of chemical and X-ray phase analysis

  15. Organometallic compounds of the lanthanides, actinides and early transition metals

    International Nuclear Information System (INIS)

    This book provides a reference compilation of physical and biographical data on over 1500 of the most important and useful organometallic compounds of the lanthanides, actinides and early transition metals representing 38 different elements. The compounds are listed in molecular formula order in a series of entries in dictionary format. Details of structure, physical and chemical properties, reactions and key references are clearly set out. All the data is fully indexed and a structural index is provided. (U.K.)

  16. Excited states and transition metal compounds with quantum Monte Carlo

    OpenAIRE

    Bande, Annika

    2007-01-01

    To the most challenging electron structure calculations belong weak interactions, excited state calculations, transition metals and properties. In this work the performance of variational (VMC) and fixed-node diffusion quantum Monte Carlo (FN-DMC) is tested for challenging electron structure problems using the quantum Monte Carlo amolqc code by Lüchow et al. The transition metal compounds under consideration are vanadium oxides. Here excitation, ionization, oxygen atom and molecule abstractio...

  17. Kinetics and thermodynamics of sorption of alkali metals ions with tin phosphate

    International Nuclear Information System (INIS)

    In order to extract microquantities of potassium from sodium iodide the sorption method with application of tin phosphate as ion exchanger is proposed. The conditions of synthesis of tin phosphate are optimized. Theoretical aspects of sorption process are considered. The kinetics of sorption of alkaline metals with amorphous tin phosphate is studied by means of limited volume method. The activation energies of sorption of alkaline metals ions are defined. Thermodynamic characteristics of process are defined as well.

  18. Release and transformation of alkali metals during co-combustion of coal and sulfur-rich wheat straw

    International Nuclear Information System (INIS)

    Highlights: • Wheat straw rich in sulfur compared to coal was chosen as biomass material. • The behavior of alkali metal species during co-combustion was investigated. • The amount of KCl(g) and NaCl(g) was decreased by adding coal to wheat straw. • Most of fuel K was retained in the bottom ash as K2SO4, KAlSiO4 and KAlSiO6. • The amount of K2SO4 in the bottom ash decreased with temperature increase. - Abstract: Co-combustion of coal and biomass is a low-cost, large-scale, and efficient way to utilize biomass energy, which has a wide range of potential applications. However, biomass, especially herbaceous fuels, contains high levels of volatile K, Na, and Cl, the use of which may result in ash-related operational problems, such as corrosion, fouling, and slagging during thermal utilization. The aim of this study is to investigate the effects of wheat straw and temperature on the release and transformation of alkali metal species during co-combustion of coal and S-rich wheat straw. Results indicate that the amounts of K and Na released during co-combustion could be reduced by the effects of Fe, Ti, S, Si, and Al from blended fuels. At lower wheat straw shares, the release of K decreased due to reactions of KCl with Fe species, and Ti species, forming K2Fe2O4 and K2TiO3. At high wheat straw shares, the release of K could be mainly captured in the form of K2SO4; small amounts of KAlSiO4 were also observed in the bottom ash. When the wheat straw share was 80 wt.%, increasing temperatures enhanced the release of KCl(g) and NaCl(g) at 600–800 °C. By contrast, in the range of 800–1000 °C, the amounts of these gases released exhibited no apparent association with temperature. Compared with the release of K, fuel K was mainly retained in the bottom ash. The K2SO4 content in the bottom ash decreased with increasing temperature in the range of 600–1000 °C, whereas the fraction of K in the form of KAlSiO4 and KAlSiO6 increased with increasing temperature

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

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V.; Goddard, William A., III

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

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

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V; Goddard, William A

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems. PMID:27001855

  1. Raman scattering in transition metal compounds: Titanium and compounds of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, J.; Ederer, D.L.; Shu, T. [Tulane Univ., New Orleans, LA (United States)] [and others

    1997-04-01

    The transition metal compounds form a very interesting and important set of materials. The diversity arises from the many states of ionization the transition elements may take when forming compounds. This variety provides ample opportunity for a large class of materials to have a vast range of electronic and magnetic properties. The x-ray spectroscopy of the transition elements is especially interesting because they have unfilled d bands that are at the bottom of the conduction band with atomic like structure. This group embarked on the systematic study of transition metal sulfides and oxides. As an example of the type of spectra observed in some of these compounds they have chosen to showcase the L{sub II, III} emission and Raman scattering in some titanium compounds obtained by photon excitation.

  2. Chemical compatibility between lithium compounds and transition metals

    International Nuclear Information System (INIS)

    The aim is to investigate the chemical reactions or otherwise of lithium compounds; Li7Pb2 (a tritium breeder), Li2O (breeder and impurity), Li3N and LiH (impurities) with containment and fusion reactor component metals - 316 and austenitic steels, titanium. Experimental details are given and results are summarized. (author)

  3. Optimized random phase approximation for the structure of liquid alkali metals as electron-ion plasmas

    International Nuclear Information System (INIS)

    The purpose of this letter is to stress that the way towards an unconventional optimized-random-phase-approximation (ORPA) approach to the structure of liquid metals is indicated, and in fact already a good first-order solution for such an approach is provided

  4. On thermal lattice dilatation of some transition metal compounds

    International Nuclear Information System (INIS)

    The report deals with the thermal lattice dilatation of cubic transition metal compounds. The thermal dilatation is determined through the variation of the lattice constants. The measurements are carried out 'in situ' by use of a high-temperature X-ray diffractometer chamber. The evaluation relates to both the linear thermal expansion coefficient α and, for some compounds, the specific heat at constant volume Csub(V) and the Grueneisen constant γ. In general a higher thermal dilatation is observed for nitrides than for carbides with the compounds formed by the transition metals belonging to the IVA and VA groups. The influence exerted by vacancies and by the oxygen dissolved in the lattice on the thermal dilatation of carbonitrides of zirconium, hafnium and tantalum is explained by the more pronounced anharmonic character of atomic vibrations in the crystal lattice. (orig.)

  5. Near-infrared luminescence enhancing by introducing alkali metal ions in Sr2CeO4:Yb3+

    International Nuclear Information System (INIS)

    NIR luminescence phosphors Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) were synthesized by conventional solid-state method in the present paper. The prepared phosphors are characterized by XRD and fluorescence spectrometer. Under UV light excitation, the NIR emission intensity of Yb3+:2F5/2→2F7/2 around 1 μm of Sr2CeO4:Yb3+ is strengthened significantly by introducing appropriate alkali metal cations dopants (Li+, Na+, K+) into the crystalline lattice. The relevant mechanisms have been discussed in detail. The peculiar optical properties make Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) promising for potential application in the high efficiency silicon-based solar cells. -- Highlights: • Pure orthorhombic Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) were successfully synthesized. • The structural and photoluminescence of these samples were characterized by XRD and fluorescence spectrometer. • The effect of Li+/Na+/K+ on the properties of samples had been researched and the relevant mechanisms have been discussed in detail. • These NIR materials could have potential application in the high efficiency silicon-based solar cells

  6. Evidence for alkali metal induced intermolecular acetylenic hydrogen atom transfer between hydrogen-bonded alkyne complexes in solid argon

    International Nuclear Information System (INIS)

    Condensation of acetylene, propyne, and 2-butyne/acetylene mixtures with heavy alkali metal atoms (Na, K, Cs) in an argon matrix at 15 K has led to the appearance of infrared absorptions due to ethylene, propylene, and trans-2-butene, respectively. These results stand in sharp contrast with the products obtained with lithium. Isotopic studies have shown that ethylene formation involved three different acetylene molecules and evidenced a difference in the product yield with hydrogen vs. deuterium as well as a preference for trans- vs. cis-C2H2D2 formation, which is discussed and rationalized by differences in the zero point energies for the different mixed deuterium isotopes of the intermediate vinyl radical. This trend is amplified by methyl substitution. Spectroscopic evidence was found in these experiments for cesium acetylide (Cs+C2H-) and a cesium-acetylene π complex, which are involved in the intermolecular acetylenic hydrogen atom transfer process. 26 references, 3 figures, 2 tables

  7. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

    International Nuclear Information System (INIS)

    Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application

  8. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

    Directory of Open Access Journals (Sweden)

    X. D. Li

    2015-05-01

    Full Text Available Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

  9. Optical probes for the detection of protons, and alkali and alkaline earth metal cations.

    Science.gov (United States)

    Hamilton, Graham R C; Sahoo, Suban K; Kamila, Sukanta; Singh, Narinder; Kaur, Navneet; Hyland, Barry W; Callan, John F

    2015-07-01

    Luminescent sensors and switches continue to play a key role in shaping our understanding of key biochemical processes, assist in the diagnosis of disease and contribute to the design of new drugs and therapies. Similarly, their contribution to the environment cannot be understated as they offer a portable means to undertake field testing for hazardous chemicals and pollutants such as heavy metals. From a physiological perspective, the Group I and II metal ions are among the most important in the periodic table with blood plasma levels of H(+), Na(+) and Ca(2+) being indicators of several possible disease states. In this review, we examine the progress that has been made in the development of luminescent probes for Group I and Group II ions as well as protons. The potential applications of these probes and the mechanism involved in controlling their luminescent response upon analyte binding will also be discussed. PMID:25742963

  10. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    Directory of Open Access Journals (Sweden)

    E. Garrone

    2002-07-01

    Full Text Available Abstract: When adsorbed (at a low temperature on alkali-metal-exchanged zeolites, CO forms both M(CO+ and M(OC+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO+ than for M(OC+ carbonyls, although the corresponding difference decreases substantially when going from Li+ to Cs+. By means of variable-temperature FTIR spectroscopy, this energy difference was determined for several alkali-metal cations, and the existence of a thermal equilibrium between M(CO+ and M(OC+ species was established. The current state of research in this field is reviewed here, with a view to gain more insight into the thermal isomerization process.

  11. Synthesis and luminescence of high-brightness Gd2O2SO4:Tb3+ nanopieces and the enhanced luminescence by alkali metal ions co-doping

    International Nuclear Information System (INIS)

    Gd2O2SO4:Tb3+ nanopieces were synthesized by a combined approach of electrospinning and calcination at 1000 °C in mixed gas of sulfur dioxide and air. The nanopieces excited by a 230 nm light showed excellent green luminescence with the strongest emission peak at 545 nm due to the 5D4→7F5 transition of Tb3+. Interestingly, the intensity of emission peak at 545 nm of Gd2O2SO4:Tb3+ nanopieces exhibited about two times stronger than that of the bulk Gd2O2SO4:Tb3+ at the same doping concentrations of Tb3+. Besides, the effects of alkali metal ions doping on the luminescence of the nanopieces have been examined. The emission intensities were further enhanced by alkali metal ions doping, especially for Gd2O2SO4:Tb3+/Li+. The optimal doping concentration of Li+ was 7%. -- Highlights: •Gd2O2SO4:Tb3+ nanopieces were prepared via electrospinning followed by calcination. •A comparison between the nanopieces and the bulk was conducted. •The effects of alkali metal ions on the luminescence of nanopieces are examined. •The content of co-dopant in nanopieces is optimized. •The potential applications of the nanopieces and the facile method are suggested

  12. Magnetometry with millimeter-scale anti-relaxation-coated alkali-metal vapor cells

    CERN Document Server

    Balabas, M V; Kitching, J; Schwindt, P D D; Stalnaker, J E

    2005-01-01

    Dynamic nonlinear magneto-optical-rotation signals with frequency- and amplitude-modulated laser light have been observed and investigated with a spherical glass cell of 3-mm diameter containing Cs metal with inner walls coated with paraffin. Intrinsic Zeeman relaxation rates of $\\gamma/(2\\pi)\\approx 20 $Hz and lower have been observed. Favorable prospects of using millimeter-scale coated cells in portable magnetometers and secondary frequency references are discussed.

  13. X-ray and neutron diffraction studies of some liquid alkali metals and alloys

    International Nuclear Information System (INIS)

    Experimental techniques and correction procedures have been searched for, which allow a reliable and accurate determination of the structure factors of simple liquid metals, particularly in the small-angle region. A study of binary alloys was carried out and showed that clustering of like atoms (a tendency to phase separation) occurs, indicating special structural aspects. The densities of Na-K, Na-Cs, K-Rb alloys were also measured. (C.F.)

  14. Construction of thermionic alkali-ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Ul Haq, F.

    1986-04-01

    A simple technique is described by which singly charged alkali ions of K, Na, Li, Rb and Cs are produced by heating ultra-pure chemical salts of different alkali metals on tungsten filaments without employing a temperature measuring device. The character of alkali-ion currents at different heating powers and the remarkably constant ion emission current for prolonged periods are discussed.

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

    Science.gov (United States)

    Joshi, Ashok V.; Balagopal, Shekar; Pendelton, Justin

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

  16. Thermal decomposition of complex halides of arsenic(3), antimony(3) and bismuth(3) with alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Cyganski, A.; Ptaszynski, B.; Zalewicz, M. (Politechnika Lodzka (Poland))

    1980-01-01

    Thermal analyses of complexes M/sub 3/(As/sub 2/X/sub 9/) (M = Rb, Cs; X = Cl, Br), M/sub 3/(Sb/sub 2/X/sub 9/) (M = Rb, Cs; X = Cl, Br, I), Rb/sub 3/(BiX/sub 6/) (X = Cl, Br) and Cs/sub 3/(Bi/sub 2/X/sub 9/) (X = Cl, Br, I) were performed. From chemical and X-ray analyses of their solid decomposition products the mechanism of thermal decomposition reactions was established. From thermogravimetric curves apparent activation energies were calculated using Coats-Redfern's and Zsako's methods. Thermal stability of complexes increases distinctly in the following order: Ascompounds of the same type.

  17. Exchange reactions in the systems of alkali metal, silver and thallium, sulfates, niobates and tantalates

    International Nuclear Information System (INIS)

    Investigated are exchange interactions in diagonal cross sections of twenty triple mutual systems with A and A' cations and SO4 and MO3 anions where A and A'-Li, Na, K, Ag, Tl, M-Nb, Ta using the methods of X-ray phase, chemical and differential thermal analyses. Exchange reaction between crystal complex oxide and melted salt are effective synthesis method. These reactions in particular permitted to obtain pure AgNbO3, AgTaO3 and their solid solutions at temperatures hundreds degrees lower than in displacement reactions. Equilibrium samples of AMO3-A'MO3 systems, continuous or discontinuous solid solutions, compounds (except NaMO3-KMO3, and also LiTaO3-KTaO3) are formed in exchange reactions when there is sulfate shortage. Thus, exchange reactions can be applied for solid solution synthesis, and also for phase diagram study

  18. IR spectra and structure of di-2-ethylhexyl phosphates of alkali and alkaline earth metals

    International Nuclear Information System (INIS)

    Using the method of IR spectroscopy (25-4000 cm-1) types of di-2-ethylhexylphosphate-anion (X-) coordination to M+ (M = Li, Na, K, Rb, Cs) and Mg2+ have been studied in solid salts and their solutions in CCl4. Analysis of IR spectra has shown that CsX in the CCl4 medium and in the solid phase exists practically only as one compound and it contains two nonequivalent bonds: M-O and M...O, i. e. the POO - group in CsX is bidentate. Besides, a small part of the CsX molecules (+ cation coordination type variation in the series from Li+ to Cs+ are discussed in connection with changes in the M+ charge density and radii. The properties of the salts and corresponding carboxylates studied are compared

  19. Dipole Polarizability of Alkali-Metal (Na, K, Rb) - Alkaline-Earth-Metal (Ca,Sr) Polar molecules - Prospects of Alignment

    CERN Document Server

    Gopakumar, Geetha; Hada, Masahiko; Kajita, Masatoshi

    2014-01-01

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

  20. Ab initio properties of the ground-state polar and paramagnetic europium-alkali-metal-atom and europium-alkaline-earth-metal-atom molecules

    CERN Document Server

    Tomza, Michał

    2014-01-01

    The properties of the electronic ground state of the polar and paramagnetic europium-$S$-state-atom molecules have been investigated. Ab initio techniques have been applied to compute the potential energy curves for the europium-alkali-metal-atom, Eu$X$ ($X$=Li, Na, K, Rb, Cs), europium-alkaline-earth-metal-atom, Eu$Y$ ($Y$=Be, Mg, Ca, Sr, Ba), and europium-ytterbium, EuYb, molecules in the Born-Oppenheimer approximation for the high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within the small-core energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large internuclear distances $C_6$ are also reported. The EuK, EuRb, and EuCs molecules are examples of species poss...

  1. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    DEFF Research Database (Denmark)

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe......, V and oxygen where at least some of the V is in the tetravalent state. USE-(I) is a cathode active material in electric current producing storage cells. ADVANTAGE-Use of (I) in Li or alkali metal batteries gives prolonged life cycles.Storage cells using (I) have improved capacity during charge and...

  2. Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

    Science.gov (United States)

    Kuzmina, O; Bordes, E; Schmauck, J; Hunt, P A; Hallett, J P; Welton, T

    2016-06-28

    The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids. PMID:27264676

  3. Organochlorine compounds in European catfish (Silurus glanis) living in river areas under the influence of a chlor-alkali plant (Ebro River basin).

    Science.gov (United States)

    Huertas, David; Grimalt, Joan O; Benito, Josep; Benejam, Lluís; García-Berthou, Emili

    2016-01-01

    European catfish, Silurus glanis, were used as sentinel organisms of the influence of recent and past discharges of organochlorine compounds (OCs) from a chlor-alkali plant located in the Ebro River. The fish concentrations of hexachlorobenzene (HCB), polychlorobiphenyls (PCBs) and DDTs were very high along the last 100 km of the river, including the irrigation channels, e.g. 1.2-27 ng/g wet weight of HCB, 6.3-100 ng/g ww of PCBs and 1-270 ng/g ww of total DDT compounds. These concentrations were much higher than those found upstream from the chlor-alkali discharge site, 0.2 ng/g ww for HCB, 5.6 ng/g ww for PCBs and 7.5 ng/g for DDT compounds. These concentrations were also standing out among those previously described in this fish species. The European catfish collected in sites under lower water flows, Ribarroja reservoir and irrigation channels, showed higher muscle lipid content, 1.09-7.2%, than those from sites of higher current intensities, river bed, 0.27%-0.67%. In these lower water current areas catfish exhibited OC ww concentrations that were correlated to % lipids. These differences suggest that normalization to lipid content is necessary for comparison of the OC accumulation in specimens from riverine systems living under different flow intensities. Accordingly, OC concentrations referred to lipid content showed more uniform downriver distribution which was consistent with a single focal point as main source of these compounds for the European catfish collected in the last 100 km of river stretch. This geographic distribution was also consistent with the uniform composition of PCB congeners in the studied European catfish. The distribution of DDT compounds was predominated by 4,4'-DDE which is common in most currently examined fish from aquatic environments. However, it included a high proportion of 4,4'-DDD and 2,4'-DDD which was consistent with the high contribution of benthic organisms from anoxic environments in the diet of these fish. PMID:26173852

  4. Complex formation during dissolution of metal oxides in molten alkali carbonates

    DEFF Research Database (Denmark)

    Li, Qingfeng; Borup, Flemming; Petrushina, Irina;

    1999-01-01

    as the partial pressure of carbon dioxide varies. By combination of solubility and electromotive force measurements, a model is constructed assuming the dissolution involves complex formation. The possible species for lead are proposed to be [Pb(CO3)(2)](-2) and/or [Pb(CO3)(3)](-4). A similar complex......Dissolution of metal oxides in molten carbonates relates directly to the stability of materials for electrodes and construction of molten carbonate fuel cells. In the present work the solubilities of PbO, NiO, Fe2O3,and Bi2O3 in molten Li/K carbonates have been measured at 650 degrees C under...... carbon dioxide atmosphere. It is found that the solubilities of NiO and PbO decrease while those of Fe2O3 and Bi2O3 remain approximately constant as the lithium mole fraction increases from 0.43 to 0.62 in the melt. At a fixed composition of the melt, NiO and PbO display both acidic and basic dissolution...

  5. An experimental study of charge exchange process in the energy range 1-30 keV during the passage of alkali metal ions and atoms through cesium and potassium vapour

    International Nuclear Information System (INIS)

    An experimental study is presented of the charge exchange processes in the energy range of about 1-30 keV during the passage of positive alkali ions and alkali atoms through potassium and cesium vapour. The experimental set-up designed for this experiment includes a thermionic source for positive alkali ions with an acceleration stage, a first charge exchange cell to produce fast alkali atoms, a second charge exchange cell with a surface ionisation detector to determine the alkali metal vapor target thickness and a detection system with electrostatic bending of the charged secondary species. The maximum negative ion yield has been determined for the collision systems Li+ + K, Na+ + K, K+ + K, and Rb+ + K, and for another eleven systems the charge transfer cross-sections have been measured too. (orig./GG)

  6. Soil sampling and analysis plan for the 3718-F Alkali Metal Treatment and Storage Facility closure activities

    International Nuclear Information System (INIS)

    Amendment V.13.B.b to the approved closure plan (DOE-RL 1995a) requires that a soil sampling and analysis plan be prepared and submitted to the Washington State Department of Ecology (Ecology) for review and approval. Amendment V.13.B.c requires that a diagram of the 3718-F Alkali Metal Treatment and Storage Facility unit (the treatment, storage, and disposal [TSD] unit) boundary that is to be closed, including the maximum extent of operation, be prepared and submitted as part is of the soil sampling and analysis plan. This document describes the sampling and analysis that is to be performed in response to these requirements and amends the closure plan. Specifically, this document supersedes Section 6.2, lines 43--46, and Section 7.3.6 of the closure plan. Results from the analysis will be compared to cleanup levels identified in the closure plan. These cleanup levels will be established using residential exposure assumptions in accordance with the Model Toxics Control Act (MTCA) Cleanup Regulation (Washington Administrative Code [WAC] 173-340) as required in Amendment V.13.B.I. Results of all sampling, including the raw analytical data, a summary of analytical results, a data validation package, and a narrative summary with conclusions will be provided to Ecology as specified in Amendment V.13.B.e. The results and process used to collect and analyze the soil samples will be certified by a licensed professional engineer. These results and a certificate of closure for the balance of the TSD unit, as outlined in Chapter 7.0 of the approved closure plan (storage shed, concrete pad, burn building, scrubber, and reaction tanks), will provide the basis for a closure determination

  7. Alkali metal Rankine cycle boiler technology challenges and some potential solutions for space nuclear power and propulsion applications

    Energy Technology Data Exchange (ETDEWEB)

    Stone, J.R.

    1994-07-01

    Alkali metal boilers are of interest for application to future space Rankine cycle power conversion systems. Significant progress on such boilers was accomplished in the 1960's and early 1970's, but development was not continued to operational systems since NASA's plans for future space missions were drastically curtailed in the early 1970's. In particular, piloted Mars missions were indefinitely deferred. With the announcement of the Space Exploration Initiative (SEI) in July 1989 by President Bush, interest was rekindled in challenging space missions and, consequently in space nuclear power and propulsion. Nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) were proposed for interplanetary space vehicles, particularly for Mars missions. The potassium Rankine power conversion cycle became of interest to provide electric power for NEP vehicles and for 'dual-mode' NTP vehicles, where the same reactor could be used directly for propulsion and (with an additional coolant loop) for power. Although the boiler is not a major contributor to system mass, it is of critical importance because of its interaction with the rest of the power conversion system; it can cause problems for other components such as excess liquid droplets entering the turbine, thereby reducing its life, or more critically, it can drive instabilities-some severe enough to cause system failure. Funding for the SEI and its associated technology program from 1990 to 1993 was not sufficient to support significant new work on Rankine cycle boilers for space applications. In Fiscal Year 1994, funding for these challenging missions and technologies has again been curtailed, and planning for the future is very uncertain. The purpose of this paper is to review the technologies developed in the 1960's and 1970's in the light of the recent SEI applications. In this way, future Rankine cycle boiler programs may be conducted most efficiently.

  8. Alkali and alkaline metal oxide materials for high temperature CO2 sorption studies

    International Nuclear Information System (INIS)

    In recent years, a number of novel ceramic oxide materials have emerged that are capable of absorbing CO2 at high temperatures (>500OC) while remaining stable over a large number of cycles and a wide range of temperatures. The most promising are been considered for carbon capture applications – specifically, for use in combustion chambers and the smoke stacks of power plants where combustion gases which contain primarily a mixture of CO2 and N2 at high temperature. Compared to other CO2 sequestration technologies, these ceramics have some advantages (eg. chemisorption at high temperatures) and disadvantages (eg. limited kinetics over time). Examples of oxides already known to show significant CO2 absorption include Li5AlO4, Li6Zr2O7, Na2ZrO3 and Ba4Sb2O9. The phase formations and structural evolution of these metal oxides have been studied under environmental conditions mimicking those found in combustion chambers and power plants, over the temperature range 873–1173 K. CO2 absorption by these materials is believed to proceed through a layering effect of the sorbent material, explained through a core-shell model. Each phase is represented as a layer covering a particle, with the outermost layer exposed and allowed to react with the environment. Detailed studies into the mechanism of CO2 absorption and the material layers will shed more information that can be used to fine tune the materials to increase their CO2 absorption capacity. Previous work has focused on the identification of phases ex situ and studies of their practical absorption capacity and kinetics. The new work we will present here uses a combination of a xray spectroscopy, x-ray and neutron diffraction, to understand both how the sorption process works and how the structural evolution of the phases affects the CO2 sorption of the materials over time in-situ.

  9. Alkaline-earth metal compounds. Oddities and applications

    International Nuclear Information System (INIS)

    This book contains the following six topics: heavy alkaline-earth metal organometallic and metal organic chemistry: synthetic methods and properties (Ana Torvisco, Karin Ruhlandt-Senge); Heavier group 2 Grignard reagents of the type aryl-ae(l)n-x post-Grignard reagents (Matthias Westerhausen, Jens Langer, Sven Krieck, Reinald Fischer, Helmar Goerls, Mathias Koehler); stable molecular magnesium(I) dimers: A fundamentally appealing yet synthetically versatile compound class (Cameron Jones, Andreas Stasch); Modern developments in magnesium reagent chemistry for synthesis (Robert E. Mulvey, Stuart D. Robertson); Alkaline-earth metal complexes in homogeneous polymerization catalysis (Jean-Francois Carpentier, Yann Sarazin); homogeneous catalysis with organometallic complexes of group 2 (Mark R. Crimmin, Michael S. Hill); Chiral Ca, Sr and Ba-catalyzed asymmetric direct-type aldol, Michael, and Mannich and related reactions (Tetsu Tsubogo, Yasuhiro Yamashita, Shu- Kobayashi).

  10. Rare Earth Metal/semiconductor Interfaces and Compounds

    Science.gov (United States)

    Nogami, Jun

    Interfaces formed at room temperature by incremental deposition of rare earth metals onto semiconductor substrates have been studied with surface sensitive soft X-ray photoelectron spectroscopy. The trends in core level lineshape and intensity with increasing metal coverage have been used to deduce an outline of the evolution and the final morphology of the interfacial region on a microscopic scale. Measurements were taken for Ytterbium (Yb) on Silicon (Si), Germanium, and Gallium Arsenide, and for Gadolinium (Gd) and Europium (Eu) on Silicon. The Yb/Si interface work was supported by comparable measurements of bulk Yb silicide samples of known composition and crystal structure. In a general sense, the behavior of all the systems studied is similar. At very low metal coverages, the metal atoms chemisorb and are weakly bonded to the substrate. The 4f core levels indicate that the metal-metal atom coordination is relatively low at this stage. The interaction with the substrate strengthens with increasing coverage, culminating in the formation of a strongly reacted phase at between 1 and 3 monolayers (ML). The strong reaction is limited to a narrow region at room temperature. At less than 10 ML coverage, the surface of the sample is almost indistinguishable from the pure metal. Details of the behavior such as the reactivity at low coverage, the compounds formed at the interface, the morphology at the surface at intermediate coverages, the final interfacial width, and the amount of substrate atom outdiffusion and surface segregation can all vary from system to system. It is in explaining the causes of some of these differences that insight about what governs the behavior of all of these rare earth metal/semiconductor systems has been obtained. The divalent metals (Yb, Eu) are significantly less reactive than trivalent Gd at sub-monolayer coverages. For the divalent metals the formation of a metal-rich phase is strongly favored in the reaction at the interface, whereas

  11. CO2 Extraction from Ambient Air Using Alkali-Metal Hydroxide Solutions Derived from Concrete Waste and Steel Slag

    Science.gov (United States)

    Stolaroff, J. K.; Lowry, G. V.; Keith, D. W.

    2003-12-01

    To mitigate global climate change, deep reductions in CO2 emissions are required in the coming decades. Carbon sequestration will play a crucial role in this reduction. Early adoption of carbon sequestration in low-cost niche markets will help develop the technology and experience required for large-scale deployment. One such niche may be the use of alkali metals from industrial waste streams to form carbonate minerals, a safe and stable means of sequestering carbon. In this research, the potential of using two industrial waste streams---concrete and steel slag---for sequestering carbon is assessed. The scheme is outlined as follows: Ca and Mg are leached with water from a finely ground bed of steel slag or concrete. The resulting solution is sprayed through air, capturing CO2 and forming solid carbonates, and collected. The feasibility of this scheme is explored with a combination of experiments, theoretical calculations, cost accounting, and literature review. The dissolution kinetics of steel slag and concrete as a function of particle size and pH is examined. In stirred batch reactors, the majority of Ca which dissolved did so within the first hour, yielding between 50 and 250 (mg; Ca)/(g; slag) and between 10 and 30 (mg; Ca)/(g; concrete). The kinetics of dissolution are thus taken to be sufficiently fast to support the type of scheme described above. As proof-of-concept, further experiments were performed where water was dripped slowly through a stagnant column of slag or concrete and collected at the bottom. Leachate Ca concentrations in the range of 15 mM were achieved --- sufficient to support the scheme. Using basic physical principles and numerical methods, the quantity of CO2 captured by falling droplets is estimated. Proportion of water loss and required pumping energy is similarly estimated. The results indicate that sprays are capable of capturing CO2 from the air and that the water and energy requirements are tractable. An example system for

  12. Calculated electronic and magnetic properties of the half-metallic, transition metal based Heusler compounds

    OpenAIRE

    Kandpal, Hem C.; FECHER, GERHARD H.; Felser, Claudia

    2006-01-01

    In this work, results of {\\it ab-initio} band structure calculations for $A_2BC$ Heusler compounds that have $A$ and $B$ sites occupied by transition metals and $C$ by a main group element are presented. This class of materials includes some interesting half-metallic and ferromagnetic properties. The calculations have been performed in order to understand the properties of the minority band gap and the peculiar magnetic behavior found in these materials. Among the interesting aspects of the e...

  13. Activation analysis for measurements of silicon, phosphorus, alkali metals and other elements in high-purity metals

    International Nuclear Information System (INIS)

    In the present thesis, methods of activation analysis were developed for the determination of the elements silicon, phosphorus, potassium, sodium, i.a. in the high-purity metals vanadium, niobium, tantalum, tungsten, molybdenum and iron. The determination of silicon is based on the activation of samples with reactor neutrons, on a subsequent radiochemical separation of the tracer radionuclide 31Si resulting from the reaction 30Si(n,γ), and on the measurement of β activity with the help of a liquid scintillation measuring desk. Since the tracer radionuclide 31Si almost exclusively emits β rays which are not sufficiently nuclide-specific, silicon was selectively separated from the other sample elements by being distilled as silicon tetrafluoride. The processing of the residue following the separation of silicon permits a complementary gamma-spectroscopic determination of a whole lot of additional elements. Thus, the separation of the nuclide 182Ta with the anion exchanger Dowex 1X8 from HF/H2SO4 medium permits the determination of 22 elements in vanadium, niobium and tantalum. Phosphorus content is determined by activating the samples with rapid neutrons (cyclotrons) via the reaction 31P(n,p)31Si. (orig./MM)

  14. Electrochemical decontamination of metallic waste contaminated with uranium compounds

    International Nuclear Information System (INIS)

    A study on the electrolytic dissolution of SUS-304 and Inconel-600 specimen was carried out in neutral salt electrolyte to evaluate the applicability of electrochemical decontamination process for recycle ro self disposal with authorization of large amount of metallic wastes contamination with uranium compounds generated by dismantling a retired uranium conversion plant in Korea. Although the best electrolytic dissolution performance for the specimens was observed in a Na2SO4 electrolyte, a Na3NO3 neutral salt electrolyte, in which about 30% for SUS-304 and the same for Inconel-600 in the weight loss was shown in comparison with that in Na2 SO4 solution, was selected as an electrolyte for the electrochemical decontamination of metallic wastes with the consideration on the surface of system components contacted with nitric acid and the compatibility with lagoon wastes generated during the facility operation. The effects of current density, electrolytic dissolution time, and concentration of NaNO3 on the electrolytic dissolution of the specimens were investigated. On the basis of the results obtained through the basic inactive experiments, electrochemical decontamination tests using the specimens contaminated with uranium compounds such as UO2, AUC (ammonium uranyl carbonate) and ADU (ammonium diuranate) taken from an uranium conversion facility were performed in 1M NaNO3 solution with the current density of 100 mA/cm2. It was verified that the electrochemical decontamination of the metallic wastes contaminated uranium compounds was quite successful in a NaNO3 neutral salt electrolyte by reducing α and β radioactivities below the level of self disposal within 10 minutes regardless of the type of contaminants and the degree of contamination.

  15. Calculation of van der Walls coefficients of alkali metal clusters by hydrodynamic approach to time-dependent density-functional theory

    CERN Document Server

    Banerjee, A; Banerjee, Arup; Harbola, Manoj K.

    2004-01-01

    In this paper we employ the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waal coefficients $C_{6}$ and $C_{8}$ of alkali-metal clusters of various sizes including very large clusters. Such calculation becomes computationally very demanding in the orbital-based Kohn-Sham formalism, but quite simple in the hydrodynamic approach. We show that for interactions between the clusters of same sizes, $C_{6}$ and $C_{8}$ sale as the sixth and the eighth power of the cluster radius rsepectively, and approach the respective classically predicted values for the large size clusters.

  16. Caracterización de nitratos alcalinos y alcalinoterreos por espectroscopia vibracional Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    OpenAIRE

    Martínez, S; Acción, F.; Puertas, F.

    1992-01-01

    [EN] Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide), employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1.387 cm~^ (present in the I.R. spectra of the four nitrates in KBr médium) allowed us to determine th...

  17. Ab initio study of the adsorption, diffusion, and intercalation of alkali metal atoms on the (0001) surface of the topological insulator Bi2Se3

    International Nuclear Information System (INIS)

    Ab initio study of the adsorption, diffusion, and intercalation of alkali metal adatoms on the (0001) step surface of the topological insulator Bi2Se3 has been performed for the case of low coverage. The calculations of the activation energies of diffusion of adatoms on the surface and in van der Waals gaps near steps, as well as the estimate of diffusion lengths, have shown that efficient intercalation through steps is possible only for Li and Na. Data obtained for K, Rb, and Cs atoms indicate that their thermal desorption at high temperatures can occur before intercalation. The results have been discussed in the context of existing experimental data

  18. Formation and properties of metallic nanoparticles on compound semiconductor surfaces

    Science.gov (United States)

    Kang, Myungkoo

    When electromagnetic radiation is incident upon metallic nanoparticles (NPs), a collective oscillation, termed a surface plasmon resonance (SPR), is generated. Recently, metallic NPs on semiconductor surfaces have enabled the generation of SPR, promising for enhanced light emission, efficient solar energy harvesting, biosensing, and metamaterials. Metallic NPs have been fabricated by focused ion beam (FIB) which has an advantage of cost-effectiveness over conventional lithography process requiring multi-step processes. Here, we report formation and properties of FIB-induced metallic NPs on compound semiconductor surfaces. Results presented in this thesis study suggest that FIB-induced Ga NPs can be a promising alternative plasmonic material. In particular, using a combined experimental-computational approach, we discovered a universal mechanism for ion-induced NP formation, which is governed by the sputtering yield of semiconductor surfaces. We also discovered a governing mechanism for ion-induced NP motion, which is driven by thermal fluctuation and anisotropic mass transport. Furthermore, we demonstrated Ga NP arrays with plasmon resonances with performance comparable to those of traditionally-used silver and gold NPs. We then finally demonstrated the Ga NP plasmoninduced enhancement of light emission from GaAs, which is the first ever combination of a new plasmonic material (Ga) and a new fabrication method (FIB) for the plasmon-enhanced light emission.

  19. Investigations on organogermanium compounds XII. Reactions of trialkylgermylalkalimetal compounds in hexamethylphosphoric triamide (HMPT) with some inorganic and organic compounds

    NARCIS (Netherlands)

    Bulten, E.J.; Noltes, J.G.

    1971-01-01

    Trialkylgermyl alkali metal compounds in HMPT have been found to be highly reactive nucleophiles. Reactions with some inorganic and organic compounds, such as oxygen, carbon dioxide, inorganic and orgaanic halides, aldehydes, ketones, epoxides and lactones are described. Several new carbon-functiona

  20. Electron and nuclear magnetic resonances in compounds and metallic hydrides

    International Nuclear Information System (INIS)

    Proton pulsed Nuclear Magnetic Resonance measurements were performed on the metallic hydrides ZrCr2Hx (x = 2, 3, 4) and ZrV2Hy (y = 2, 3, 4, 5) as a function of temperature between 180 and 400K. The ultimate aim was the investigation of the relaxation mechanisms in these systems by means of the measurement of both the proton (1H) spin-lattice (T1) and spin-spin (T2) relaxation times and to use these data to obtain information about the diffusive motion of the hydrogen atoms. The diffusional activation energies, the jump frequencies and the Korringa constant, Ck, related with the conduction electron contribution to the 1H relaxation were determined for the above hydrides as a function of hydrogen concentration. Our results were analysed in terms of the relaxation models described by Bloembergen, Purcell and Pound (BPP model) and by Torrey. The Korringa type relaxation due to the conduction electrons in metallic systems was also used to interpret the experimental results. We also present the Electron Paramagnetic Ressonance (EPR) study of Gd3+, Nd3+ and Er3+ ions as impurities in several AB3 intermetallic compounds where A = LA, Ce, Y, Sc, Th, Zr and B = Rh, Ir, Pt. The results were analysed in terms of the multiband model previously suggested to explain the behaviour of the resonance parameter in AB2 Laves Phase compounds. (author)

  1. From T2,2@Bmmim to Alkali@T2,2@Bmmim Ivory Ball-like Clusters: Ionothermal Syntheses, Precise Doping, and Photocatalytic Properties.

    Science.gov (United States)

    Du, Cheng-Feng; Li, Jian-Rong; Zhang, Bo; Shen, Nan-Nan; Huang, Xiao-Ying

    2015-06-15

    Presented here are the syntheses, structures, and properties of an In-Sn-Se compound based on a ternary super-supertetrahedral T2,2 cluster nested by Bmmim cations and two of its alkali-doped quaternary analogues. By means of a one-pot ionothermal method, an alkali metal ion (Cs(+) or Rb(+)) could be precisely doped into the central cavity of the cluster, forming an alkali@T2,2@Bmmim quaternary cluster. Remarkably, the undoped compound exhibited excellent stability and visible light photodegradation ability over a wide range of pH, especially in acidic conditions. PMID:26034842

  2. Atomic arrangement and electron band structure of Si(1 1 1)-ß-√3 x √3-Bi reconstruction modified by alkali-metal adsorption: ab initio study.

    Science.gov (United States)

    Eremeev, S V; Chukurov, E N; Gruznev, D V; Zotov, A V; Saranin, A A

    2015-08-01

    Using ab initio calculations, atomic structure and electronic properties of Si(1 1 1)[Formula: see text]-Bi surface modified by adsorption of 1/3 monolayer of alkali metals, Li, Na, K, Rb and Cs, have been explored. Upon adsorption of all metals, a similar atomic structure develops at the surface where twisted chained Bi trimers are arranged into a honeycomb network and alkali metal atoms occupy the [Formula: see text] sites in the center of each honeycomb unit. Among other structural characteristics, the greatest variation concerns the relative heights at which alkali metals reside with respect to Bi-trimer layer. Except for Li, the other metals reside higher than Bi layer and their heights increase with atomic number. All adsorbed surface structures display similar electron band structures of which the most essential feature is metallic surface-state band with a giant spin splitting. This electronic property allows one to consider the Si(1 1 1)[Formula: see text]-Bi surfaces modified by alkali metal adsorption as a set of material systems showing promise for spintronic applications. PMID:26151642

  3. Adsorption of humic acid by bi-functional resin JN-10 and the effect of alkali-earth metal ions on the adsorption

    International Nuclear Information System (INIS)

    This study investigated the adsorption of humic acid (HA) by bi-functional resin JN-10, which removed the HA more effectively than the commercial resins D-301, D-201, XAD-7, and globe active carbon F-400. The difference between the FT-IR spectroscopy and 13C NMR analysis of JN-10 before and after it adsorbing the HA revealed that both hydrophobic interaction and electric attraction were the adsorption force for the HA. The related thermodynamic parameters exhibited that the adsorption of the HA by JN-10 was an endothermic process. The occurring of adsorption was due to the increase of entropy, and the electric attraction was also a main adsorption force. In order to investigate the influence of the molecule weight (MW) of the HA on its removal by JN-10, the HA with the MWs ranging from 2000 to 100,000 Da was divided into six fractions by ultra-filtration. The HA with a medium MW (6000-10,000 Da) was preferentially removed by JN-10 due to the synergistic effect of hydrophilicity, molecular size, and aromaticity of the HA. The adsorption capacity of JN-10 for the HA increased in the presence of low concentration of alkali-earth metal ions Ca2+ and Mg2+, which neutralized the negative charges of the HA, but it decreased as the concentration of these ions increased because the hydrates formed by the alkali-earth metal ions occupied the adsorption sites of the resin.

  4. Crystal growth and evaluation of scintillation properties of Eu and alkali-metal co-doped LiSrAlF6 single crystals for thermal neutron detector

    International Nuclear Information System (INIS)

    In recent work, Na co-doping have found to improve the light output of Eu doped LiCaAlF6 (Eu:LiCAF) for thermal neutron scintillator. We grew Eu 2% and alkali metal 1% co-doped LiSAF crystals by Micro-Pulling down method to understand the effect of alkali metal co-doping on scintillation properties and mechanism compared with LiCAF. In photo- and α-ray induced radio-luminescence spectra of the all grown crystals, the emissions from d-f transition of Eu2+ were observed. Without relation to excitation source, decay times of co-doped LiSAF were longer than Eu only doped one. The light yield of Na, K and Cs co-doped LiSAF under 252Cf neutron excitation were improved. Especially, K co-doped Eu:LiSAF reached 33200 ph/n, which outperformed Eu only doped one by approximately 20% (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Production of Synthesis Gas via Methane Reforming with CO2 on Ni/SiO2 Catalysts Promoted by Alkali and Alkaline Earth Metals

    Institute of Scientific and Technical Information of China (English)

    陈平; 侯昭胤; 郑小明

    2005-01-01

    Ni/SiO2 catalysts promoted by alkali metals K and Cs or alkaline earth metals Mg, Ca, Sr and Ba were prepared, characterized by H2-TPR and XRD, and used for the production of synthesis gas via methane reforming with CO2. Though K and Cs promoted Ni catalysts could eliminate coke deposition, the reforming activity of these promoted catalysts was decreased heavily. Mg and Ca promoted Ni/SiO2 catalysts exhibited excellent coke resistance ability with minor loss of the reforming activity of Ni/SiO2. Ba showed poor coke resistance ability and small amount of Sr increased the formation of coke. The possible mechanism of these promoters was discussed.

  6. Electrocatalysis of the oxidations of some organic compounds on noble-metal electrodes by foreign-metal ad-atoms

    International Nuclear Information System (INIS)

    Electrochemical oxidation of formic acid was studied on Pt electrodes in acid, and that of dextrose was studied on Pt and Au in alkali. Poisoning was observed on Pt but not on Au. Several heavy-metal ad-atoms (Pb, Bi, Tl) enhance greatly the anodic currents on Pt, while transition metals (Cu, Zn) inhibit the oxidation on Pt. The enhancement effect of the metal ad-atoms is correlated with electron structure. All metal ad-atoms showed an inhibitory effect on Au. Amperometry showed that Pt electrodes are completely deactivated within 10 s during dextrose oxidation without ad-atoms, while Au retains much of its activity even after 10 min. Ad-atoms maintains the Pt activity over much more than 10 s. 50 figures, 38 tables

  7. Bonding in transition-metal cluster compounds. 2. The metal cluster-borane analogy

    International Nuclear Information System (INIS)

    Following the detailed discussion of the transition-metal cluster moiety M6(μ3-X)8 in the preceding paper, a more general account of the importance of the d electrons in transition-metal cluster chemistry is presented. The putative analogy with borane clusters (and their derivatives) is examined critically. Although an isolobal relationship exists between, e.g., BH and appropriate ML/sub n/ fragments (e.g. conical Fe(CO)3), this does not imply that the BH and ML/sub n/ fragments behave in electronically similar ways when cluster formation occurs, even when structurally related clusters are formed. Nonidentical isolobal fragments have orbital differences that manifest themselves in interfragment resonance integrals and require a qualitative distinction to be drawn between the bonding modes and detailed electronic structures of (i) transition-metal cluster compounds and (ii) boranes, carboranes, and their metalla derivatives; an analysis developed in the electronic structure theory of transition-metal systems shows why this is the case. The isolobal principle and Wade's rule owe their generality and utility to being symmetry-based statements; the energetics and details of the electronic structure of cluster compounds however are a separate matter requiring appropriate methods of theoretical chemistry. 39 references, 3 figures

  8. HPIC separation and quantification of Ca and Fe in uranium metal and alloy compounds

    International Nuclear Information System (INIS)

    The paper describes the separation and quantification of Ca and Fe from uranium metal and uranium based alloy fuels employing ion chromatography (IC). Ca separation from other metal ions of alkali and alkaline groups was carried out on a cation exchange column and the same was detected and quantified by means of conductivity detector. In case of Fe, it was separated from other transition elements using chelation ion chromatography where detection and quantification was carried out photometrically after the addition of PAR as post column reagent. For both the analyses a preliminary column chromatography separation for eliminating the bulk matrix uranium was performed. (author)

  9. Catalytic mechanism of transition-metal compounds on Mg hydrogen sorption reaction.

    Science.gov (United States)

    Barkhordarian, Gagik; Klassen, Thomas; Bormann, Rüdiger

    2006-06-01

    The catalytic mechanisms of transition-metal compounds during the hydrogen sorption reaction of magnesium-based hydrides were investigated through relevant experiments. Catalytic activity was found to be influenced by four distinct physico-thermodynamic properties of the transition-metal compound: a high number of structural defects, a low stability of the compound, which however has to be high enough to avoid complete reduction of the transition metal under operating conditions, a high valence state of the transition-metal ion within the compound, and a high affinity of the transition-metal ion to hydrogen. On the basis of these results, further optimization of the selection of catalysts for improving sorption properties of magnesium-based hydrides is possible. In addition, utilization of transition-metal compounds as catalysts for other hydrogen storage materials is considered. PMID:16771356

  10. QED radiative corrections and many-body effects in atoms: the Uehling potential and shifts in alkali metals

    CERN Document Server

    Ginges, J S M

    2015-01-01

    We consider the largest (Uehling) contribution to the one-loop vacuum polarization correction to the binding energies in neutral alkali atoms, from Na through to the superheavy element E119. We use the relativistic Hartree-Fock method to demonstrate the importance of core relaxation effects. These effects are sizeable everywhere, though particularly important for orbitals with angular momentum quantum number l > 0. For d waves, the Uehling shift is enhanced by many orders of magnitude: for Cs the enhancement is more than four orders of magnitude and for the lighter alkali atoms it is even larger. We also study the effects of second- and higher-order many-body perturbation theory on the valence level shifts through inclusion of the correlation potential. The many-body enhancement mechanisms that operate in the case of the Uehling potential apply also to the case of the larger QED self-energy radiative corrections. The huge enhancement for d level shifts makes high-precision studies of transition frequencies in...

  11. Improved thermoelectric performance in polycrystalline p-type Bi2Te3 via an alkali metal salt hydrothermal nanocoating treatment approach

    Science.gov (United States)

    Ji, Xiaohua; He, Jian; Su, Zhe; Gothard, Nick; Tritt, Terry M.

    2008-08-01

    We report herein a proof-of-principle study of grain boundary engineering in the polycrystalline p-type Bi2Te3 system. Utilizing the recently developed hydrothermal nanocoating treatment technique, we fabricated an alkali-metal(s)-containing surface layer on the p-Bi2Te3 bulk grain, which in turn became part of the grain boundary upon hot pressing densification. Compared to the untreated bulk reference, the dimensionless figure of merit ZT has been improved by ˜30% in the Na-treated sample chiefly due to the reduced thermal conductivity, and ˜38% in the Rb-treated sample mainly owing to the improved power factor. The grain boundary phase provides a new avenue by which one can potentially decouple the otherwise inter-related electrical resistivity, Seebeck coefficient, and thermal conductivity within one thermoelectric material.

  12. "XA6" octahedra influencing the arrangement of anionic groups and optical properties in inverse-perovskite [B6O10]XA3 (X = Cl, Br; A = alkali metal).

    Science.gov (United States)

    Yang, Zhihua; Lei, Bing-Hua; Yang, Bin; Pan, Shilie

    2016-06-01

    Exploring the effect of microscopic units, which set up the perovsikte framework, is of importance for material design. In this study, a series of borate halides with inverse-perovskite structures [B6O10]XA3 (X = Cl, Br; A = alkali metal) have been studied. It was revealed that the distortion and volume of XA6 octahedra influence the arrangement of anionic groups, which leads to the flexibility of the perovskite-related framework and differences in optical properties. Under the structural control scheme, the structure of Rb3B6O10Cl was predicted. The stability of the predicted structure was confirmed by an ab initio density functional theory-based method. The calculation shows Rb3B6O10Cl has a short UV cutoff edge of less than 200 nm, a moderate birefringence and a large second harmonic generation response. PMID:27211304

  13. On-line alkali monitoring - Part 1

    International Nuclear Information System (INIS)

    As a consequence of the increased knowledge of the environmental impact of combustion based heat and power generation, the use of renewable biofuels will be increased. An obstacle associated to biofuel combustion compared to other fuels is the large release of alkali. Alkali compounds in flue gases are known to cause severe operational problems. Three of the major problems are; fouling of superheating tubes (causing reduced heat transfer and possibly corrosion), agglomeration of the bed material in fluidized beds, and poisoning of SCR catalysts. Yet another alkali related problem arises when, in order to increase the electric efficiency of combustion power plants, combined-cycle technology is used. Alkali vapour present in the fuel gas for the gas turbine is condensed to particles which increase corrosion and erosion of the turbine blades. The research on ash related operational problems has to be extended in order to ensure future use of biofuels in heat and power generation. In all successful research, adequate tools are necessary. To investigate ash related problems the key issue is to be able to perform continuous alkali measurements. This pilot study has investigated the need of continuous alkali measurements, which alkali species are harmful in the different applications and also available instrumentation capable of measuring the specific alkali species. The report gives a short summary presenting alkali related operational problems. In addition a schematic overview is given, showing the alkali species that possibly can exist in various parts of the power plant. 48 refs, 13 figs, 4 tabs

  14. Alkali metal ion-proton exchange equilibria and water sorption studies on nafon 117 membrane and dowex 50 W exchange resins: effect of long storage or aging

    International Nuclear Information System (INIS)

    Alkali metal ion -H+ exchanges on Nafion 117 membrane treated differently, Dowex 50 W x 4 and Dowex 50 W x 8 resins have been studied at a total ionic strength of 0.1 mol dm-3. The water sorption isotherms of these exchangers in different ionic forms generated over the entire range of water activity, have been analysed by the D'Arcy and Watt equation (DWE). Water sorption studies have shown that the physical structure of the exchangers have changed due to long -storage or aging, resulting in poorer water sorption and even formation of pores in the case of Dowex 50 W x 8 resin. As a result, the counter ions in the exchangers are not hydrated and the water is present in a free form, albeit structured, in the resin phase. The selectivity sequence for the alkali metal ions with reference to the H+ (Li+++) for the exchangers used in the present study is in accordance with that reported in the literature for the ionomers having sulphonic acid as the functional group. In view of the absence of hydration of the cations in the resin phase, the driving force for the selectivity of the cation, namely, the net gain in entropy, is expected to come from the loss of structured water during the exchange process. Pre treating the Nafion 117 membrane with boiling acid solution activates the clustered region of the membrane in the H+ form, while pretreatment with boiling water expands the non-ionic domain (the region connecting the clusters). These modifications influence the state of water present in the Nafion 117 membrane and the ion exchange equilibria. As a result of long storage or aging, the ion exchangers lose their elasticity or swelling characteristics. The results obtained in the present study indicate that in aged materials, the ionogenic groups are existing as isolated ion -pairs rather than in a clustered morphology. (author)

  15. Design study of a 200 MW(e) alkali metal/steam binary power plant using a coal-fired fluidized bed furnace

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, G.; Graves, R. L.; Lackey, M. E.; Tudor, J. J.; Zimmerman, G. P.

    1978-04-01

    The results of a study of 200 MW(e) alkali metal/steam binary power plant using a coal-fired fluidized bed furnace are described. Both cesium and potassium were evaluated for the topping cycle working fluid and cesium was selected. The fuel used was Illinois No. 6 coal, and limestone was used as the bed sorbent material. For the reference design, the furnace operated at atmospheric pressure and the cycle conditions for the power conversion system were 1500/sup 0/F to 900/sup 0/F for the topping cycle and 2400 psi 1000/sup 0/F to 1/sup 1///sub 2/ in. Hg for the steam system. Several variations of the plant were briefly evaluated. These variations included using a supercritical steam system and using a pressurized furnace. The principal conclusions of the study are as follows: a satisfactory design of an atmospheric pressure fluidized bed furnace binary power plant was evolved which uses a variation of the conventional binary cycle which permits utilizing the full potential of the alkali metal topping cycle; the net plant efficiency (coal to busbar) of the reference system was 44.6%; the net plant efficiency of a larger system with a 3500 psi 1000/sup 0/F steam system was 46.8%; an intermediate pressure turbocharged system with a furnace pressure of 4 atm (0.4 MPa) would have many advantages in comparison to the atmospheric pressure system, including a plant efficiency about one percentage point higher than the reference design, reduced limestone requirement and potential capital cost saving; and although cost estimates were not a part of the design study, a comparison of the design of this study to that of the Energy Conversion Alternative Study (ECAS) indicates plant costs 20 to 25% less than that of the final ECAS design.

  16. Alkali metal ions transfer across a water/1,2-dichloroethane interface facilitated by a novel monoaza-B15C5 derivative

    Energy Technology Data Exchange (ETDEWEB)

    Zhan Dongping; Yuan Yi; Xiao Yanjing; Wu Bingliang; Shao Yuanhua

    2002-10-30

    In this paper, a novel monoaza-B15C5 derivative, N-(2-tosylamino)-isopentyl-monoaza-15-crown-5 (L), is used as an ionophore to facilitate alkali metal cations transfer across a water/1,2-dichloroethane (W/DCE) interface. Well-defined voltammetric behaviors are observed at the polarized W/DCE interfaces supported at micro- and nano-pipets except Cs{sup +}. The diffusion coefficient of this ionophore in the DCE phase is calculated to be equal to (3.3{+-}0.2)x10{sup -6} cm{sup 2} s{sup -1}. The experimental results indicate that a 1:1 (metal:ionophore) complex is formed at the interface with a TIC/TID mechanism. The selectivity of this ionophore towards alkali ions follows the sequence Na{sup +}>Li{sup +}>K{sup +}>Rb{sup +}>Cs{sup +}. The logarithm of the association constants (log {beta}{sub 1}{sup o}) of the LiL{sup +}, NaL{sup +}, KL{sup +} and RbL{sup +} complexes in the DCE phase are calculated to be 10.6, 11.6, 9.0 and 7.1, respectively. The kinetic parameters are determined by steady-state voltammograms using nanopipets. The standard rate constants (k{sup 0}) for Li{sup +}, Na{sup +}, K{sup +} and Rb{sup +} transfers facilitated by L are 0.54{+-}0.05, 0.63{+-}0.09, 0.51{+-}0.04 and 0.46{+-}0.06 cm s{sup -1}, respectively. The pH values of aqueous solution have little effect on the electrochemical behaviors of these facilitated processes. The results predicate that this new type of ionophore might be useful to fabricate electrochemical sensor of sodium ion.

  17. Insertion compounds of uranium oxides

    International Nuclear Information System (INIS)

    Insertion compounds are formed by the intercalation of an electropositive species, such as hydrogen or an alkali metal, with minimal structural rearrangement of the host oxide. In this report a review of the measured structural, thermodynamic and transport properties of the insertion compounds of α-U3O8, α-UO3, γ-UO3, δ-UO3 and related systems is given. (author)

  18. Reclamation of reactive metal oxides from complex minerals using alkali roasting and leaching- an improved approach to process engineering

    OpenAIRE

    Sanchez Segado, S; Makanyire, T; Escudero-Castejon, L; Hara, Y.; Jha, A.

    2015-01-01

    In nature, the commonly occurring reactive metal oxides of titanium, chromium, aluminium, and vanadium often chemically combine with the transition metal oxides such as iron oxides and form complex minerals. Physico-chemical separation of transition metal oxides from the remaining reactive metal oxides is therefore an important step in the purification of reactive oxide constituents. Each purification step has quite a high energy requirement at present. Current practice in industry yields sul...

  19. QED radiative corrections and many-body effects in atoms: vacuum polarization and binding energy shifts in alkali metals

    Science.gov (United States)

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

    2016-05-01

    We calculate vacuum polarization corrections to the binding energies in neutral alkali atoms Na through to the superheavy element E119. We employ the relativistic Hartree–Fock method to demonstrate the importance of relaxation of the electronic core and the correlation potential method to study the effects of second and higher orders of perturbation theory. These many-body effects are sizeable for all orbitals, though particularly important for orbitals with angular momentum quantum number l\\gt 0. The orders of magnitude enhancement for d waves produces shifts that, for Rb and the heavier elements, are larger than those for p waves and only an order of magnitude smaller than the s-wave shifts. The many-body enhancement mechanisms that operate for vacuum polarization apply also to the larger self-energy corrections.

  20. Lifetime studies of high power rhodium/tungsten and molybdenum electrodes for application to AMTEC (alkali metal thermal-to-electric converter)

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter (AMTEC) is a passive, direct energy conversion device potentially capable of near-Carnot efficiencies and demonstrated to perform to 19% efficiency and up to 1.0 W/cm2 power densities. It utilizes a high sodium activity gradient across a beta alumina solid electrolyte (BASE) and the properties of the porous metal electrode (PME) on the low pressure side of the electrolyte is critical to device performance. Sintering of the electrode, reaction between its constituents and BASE at their common interface, and metal migration within the electrode structure are all potential routes to long term degradation of electrode performance. Evaluation of these processes, which often may be measured at levels far below those affecting overall electrode performance, is necessary to construction of a valid lifetime performance model for AMTEC electrodes. Results of modeling with the limited available data indicate that thin Mo electrodes may show significant performance degradation for extended operation (>10,000 hrs) at higher operating temperatures (>1150K), while W/Rh and W/Pt electrodes are expected to show adequate performance at 1200K for lifetimes >10,000 hrs

  1. Structural phase stability, electronic structure and mechanical properties of alkali metal hydrides AMH4 (A=Li, Na; M=B, AL)

    Science.gov (United States)

    Santhosh, M.; Rajeswarapalanichamy, R.

    2016-01-01

    The structural stability of Alkali metal hydrides AMH4 (A=Li, Na; M=B, Al) is analyzed among the various crystal structures, namely hexagonal (P63mc), tetragonal (P42/nmc), tetragonal (P-421c), tetragonal (I41/a), orthorhombic (Pnma) and monoclinic (P21/c). It is observed that, orthorhombic (Pnma) phase is the most stable structure for LiBH4, monoclinic (P21/c) for LiAlH4, tetragonal (P42/nmc) for NaBH4 and tetragonal (I41/a) for NaAlH4 at normal pressure. Pressure induced structural phase transitions are observed in LiBH4, LiAlH4, NaBH4 and NaAlH4 at the pressures of 4 GPa, 36.1 GPa, 26.5 GPa and 46 GPa respectively. The electronic structure reveals that these metal hydrides are wide band gap insulators. The calculated elastic constants indicate that these metal hydrides are mechanically stable at normal pressure.

  2. Thermodynamic and structural properties of ball-milled mixtures composed of nano-structural graphite and alkali(-earth) metal hydride

    International Nuclear Information System (INIS)

    Hydrogen desorption properties of mechanically milled materials composed of nano-structural hydrogenated-graphite (CnanoH x) and alkali(-earth) metal hydride (MH; M = Na, Mg and Ca) were investigated from the thermodynamic and structural points of view. The hydrogen desorption temperature for all the CnanoH x and MH composites was obviously lower than that of the corresponding each hydride. In addition, the desorption of hydrocarbons from CnanoH x was significantly suppressed by making composite of CnanoH x with MH, even though CnanoH x itself thermally desorbs a considerably large amount of hydrocarbons. These results indicate that an interaction exists between CnanoH x and MH, and hydrogen in both the phases is destabilized by a close contact between polar C-H groups in CnanoH x and the MH solid phase. Moreover, a new type of chemical bonding between the nano-structural carbon (Cnano) and the Li, Ca, or Mg metal atoms may be formed after hydrogen desorption. Thus, the above metal-C-H system would be recognized as a new family of H-storage materials

  3. Attaching an alkali metal atom to an alkaline earth metal oxide (BeO, MgO, or CaO) yields a triatomic metal oxide with reduced ionization potential and redirected polarity.

    Science.gov (United States)

    Nowiak, Grzegorz; Skurski, Piotr; Anusiewicz, Iwona

    2016-04-01

    The existence of a series of neutral triatomic metal oxides MON and their corresponding cations MON (+) (M = Be, Mg, Ca; N = Li, Na, K) was postulated and verified theoretically using ab initio methods at the CCSD(T)/6-311+G(3df)//MP2/6-311+G(3df) level of theory. The calculations revealed that the vertical ionization potentials (IPs) of the MON radicals (calculated using the outer-valence Green's function technique (OVGF) with the 6-311+G(3df) basis set) were ca. 2-3 eV smaller than the IPs of the corresponding MO and NO systems or that of the isolated M atom. Population analysis of the neutral triatomic MON molecules and their corresponding MO counterparts indicated that the attachment of an alkali metal atom to any oxide MO (BeO, MgO, CaO) reverses its polarity, which manifests itself as the redirection of the dipole moment vector. PMID:26994021

  4. Structural changes of polyacids initiated by their neutralization with various alkali metal hydroxides. Diffusion studies in poly(acrylic acid)s.

    Science.gov (United States)

    Masiak, Michal; Hyk, Wojciech; Stojek, Zbigniew; Ciszkowska, Malgorzata

    2007-09-27

    The changes in the three-dimensional structure of the poly(acrylic acid), PAA, induced by incorporation of various alkali-metal counterions have been evaluated by studying diffusion of an uncharged probe (1,1'-ferrocenedimethanol) in the polymeric media. The studies are supported by the measurements of conductivity and viscosity of the polymeric media. Solutions of linear PAA of four different sizes (molecular weights: 450,000, 750,000, 1,250,000, 4,000,000) were neutralized with hydroxides of alkali metals of group 1 of the periodic table (Li, Na, K, Rb, Cs) to the desired neutralization degree. The transport properties of the obtained polyacrylates were monitored by measuring the changes in the probe diffusion coefficient during the titration of the polyacids. The probe diffusivity was determined from the steady-state current of the probe voltammetric oxidation at disk microelectrodes. Diffusivity of the probe increases with the increase in the degree of neutralization and with the increase in viscosity. It reaches the maximum value at about 60-80% of the polyacid neutralization. The way the probe diffusion coefficients change is similar in all polyacid solutions and gels. The increase in the size of a metal cation causes, in general, an enhancement in the transport of probe molecules. The biggest differences in the probe diffusivities are between lithium and cesium polyacrylates. The differences between the results obtained for cesium and rubidium are not statistically significant due to lack of good precision of the voltammetric measurements. The measurements of the electric conductivity of polyacrylates and the theoretical predictions supplemented the picture of electrostatic interactions between the polyanionic chains and the metal cations of increasing size. In all instances of the PAAs, the viscosity of the solutions rapidly increases in the 0-60% range of neutralization and then becomes constant in the 60-100% region. With the exception of the shortest

  5. Coordination compounds of transition metal chlorides with tetrazoles

    International Nuclear Information System (INIS)

    Coordination compounds (CC) of Co(2), Ni(2), Cu(2), Cd(2) chlorides with tetrazole and Ni(2) and Cd(2) chloride CC with tetrazolylhydrazone benzaldehyde are synthesized. The compounds are characterized by electron- and IR-spectroscopy, magnetic measurements (78-300 K), radiography. Conclusions are made on polynuclear structure of coordination compounds and Msup((2)) octahedron coordination

  6. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    International Nuclear Information System (INIS)

    In this paper, we systematically investigate the electronic structure for the 2Σ+ ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained

  7. Theoretical study on the ground state of the polar alkali-metal-barium molecules: potential energy curve and permanent dipole moment.

    Science.gov (United States)

    Gou, Dezhi; Kuang, Xiaoyu; Gao, Yufeng; Huo, Dongming

    2015-01-21

    In this paper, we systematically investigate the electronic structure for the (2)Σ(+) ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained. PMID:25612710

  8. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Dezhi; Kuang, Xiaoyu, E-mail: scu-kuang@163.com; Gao, Yufeng; Huo, Dongming [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)

    2015-01-21

    In this paper, we systematically investigate the electronic structure for the {sup 2}Σ{sup +} ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained.

  9. Towards new molecular superconductors: a first study of alkali metal reduced aromatic cryptands as 'pseudo-fullerides'

    International Nuclear Information System (INIS)

    The search for new molecular superconductors based upon concepts derived from the interpretation of alkali fullerides superconductivity led to the study of an aromatic cryptand (IHIC) considered as 'pseudo-fullerene'. New solids made of IHIC mono or di-reduced by potassium, rubidium and cesium were investigated. Low field microwave absorption (LFMA) signals appeared at 20 K for IHIC-Rb and IHIC-K (1:1), although these observations could not be confirmed by AC susceptibility or SQUID magnetometry. IR spectroscopy was used to probe the integrity of the final solid. EPR spectra consisted of a single symmetric line, combination of a Gaussian and of a Lorentzian lineshape, down to 4.2 K. However, the paramagnetic contribution of the reduced molecular species was too high to allow the observation of any transition at low temperature. Although two samples had a semiconductor like conductivity behavior as a function of temperature at high temperature, no indication of the presence of conduction electrons could be observed on the EPR spectrum. The LFMA measurements obtained can be considered as hints of superconductivity, thus opening the route towards new materials. (orig.)

  10. Transformation of Heavy Metal Compounds during the Remediation of Contaminated Soils

    Directory of Open Access Journals (Sweden)

    Tatiana Minkina

    2011-03-01

    Full Text Available The effect of ameliorants, chalk, glauconite and semidecomposed cattle manure, on ordinary chernozem contaminated with Zn and Pb was studied in a long-term field experiment. The application of ameliorants significantly decreased the mobility of metals. Their effect depended on the ameliorant and was most significant at the simultaneous application of chalk and manure. This effect was presumably due to the strong binding of metals by carbonates through chemisorption and formation of lowsoluble Zn and Pb compounds and to the additional fixation in the form of complexes at the addition of organic material. The share of loosely bound metal compounds in the contaminated soils decreased to the level typical for the clean soils or even below. The general evolution of the transformation of metal compounds (from less to more firmly bound compounds accelerated by ameliorants remained for both metals.

  11. Binding energy referencing for XPS in alkali metal-based battery materials research (I): Basic model investigations

    International Nuclear Information System (INIS)

    Highlights: • We point to a not seriously solved conflict in energy scale referencing of Li metal samples in XPS. • Model experiments at Li-, Na-metal and Li-doped HOPG samples were used to classify the effects. • Binding energy shifts up to 3 eV are observed when the alkaline metal is present in metallic state. • A phenomenological explanation based on an electrostatic interaction is suggested. • Consequences for energy scale correction depending on the kind of surface species are followed. - Abstract: For the investigation of chemical changes in Li- and Na-ion battery electrode systems, X-ray photoelectron spectroscopy (XPS) is a well-accepted method. Charge compensation and referencing of the binding energy (BE) scale is necessary to account for the involved mostly non-conducting species. Motivated by a conflict in energy scale referencing of Li-metal samples discussed earlier by several authors, further clarifying experimental results on several Li containing reference materials are presented and extended by similar experiments for Na. When correlating the peak positions of characteristic chemical species in all the different prepared model sample states, there seems to be a systematic deviation in characteristic binding energies of several eV if lithium is present in its metallic state. Similar results were found for sodium. The observations are furthermore confirmed by the implementation of inert artificial energy reference material, such as implanted argon or deposited gold. The behavior is associated with the high reactivity of metallic lithium and a phenomenological explanation is proposed for the understanding of the observations. Consequences for data interpretation in Li-ion battery research will be discussed for various applications in part (II)

  12. Binding energy referencing for XPS in alkali metal-based battery materials research (I): Basic model investigations

    Energy Technology Data Exchange (ETDEWEB)

    Oswald, S., E-mail: s.oswald@ifw-dresden.de

    2015-10-01

    Highlights: • We point to a not seriously solved conflict in energy scale referencing of Li metal samples in XPS. • Model experiments at Li-, Na-metal and Li-doped HOPG samples were used to classify the effects. • Binding energy shifts up to 3 eV are observed when the alkaline metal is present in metallic state. • A phenomenological explanation based on an electrostatic interaction is suggested. • Consequences for energy scale correction depending on the kind of surface species are followed. - Abstract: For the investigation of chemical changes in Li- and Na-ion battery electrode systems, X-ray photoelectron spectroscopy (XPS) is a well-accepted method. Charge compensation and referencing of the binding energy (BE) scale is necessary to account for the involved mostly non-conducting species. Motivated by a conflict in energy scale referencing of Li-metal samples discussed earlier by several authors, further clarifying experimental results on several Li containing reference materials are presented and extended by similar experiments for Na. When correlating the peak positions of characteristic chemical species in all the different prepared model sample states, there seems to be a systematic deviation in characteristic binding energies of several eV if lithium is present in its metallic state. Similar results were found for sodium. The observations are furthermore confirmed by the implementation of inert artificial energy reference material, such as implanted argon or deposited gold. The behavior is associated with the high reactivity of metallic lithium and a phenomenological explanation is proposed for the understanding of the observations. Consequences for data interpretation in Li-ion battery research will be discussed for various applications in part (II)

  13. Experimental and theoretical determinations of the absolute ionization cross section of alkali metals by electron impact in the energy range from 100 to 2000 eV

    International Nuclear Information System (INIS)

    The absolute electron impact ionization cross sections for the alkali metals in the energy range between 100 eV and 2000 eV were measured by the non-modulated crossed beam technique. The neutral beam of alkali atoms is produced by a Knudsen cell and crossed at right angles with the electron beam. The ions formed are collected on a plate and their intensity determined with a D.C. amplifier. The neutral beam is condensed on a cold trap cooled with liquid nitrogen, this temperature being much lower than that required to obtain total condensation. The amount of metal deposited is measured by the isotopic dilution technique and by atomic absorption, and the density of the atoms in the neutral beam is calculated. The total absolute ionization cross sections can then be determined. All possible errors have been carefully analyzed and their magnitudes estimated. The absolute ionization cross section for Li at an energy of 500 eV is: QLi = 0,358 x 10-16 cm2. This value is half of that obtained by Mac Farland and Kinney. The partial ionization cross sections for the singly and multiply charged ions is determined with a mass spectrometer attached to this apparatus. For the singly charged ions, the variation of the cross section with the energy of the ionizing electrons is in agreement with the optically allowed transition law: Q = A log BE/E. From the variation of Q with E, the squared matrix elements of the transition moment (|Mi|)2 are determined for all the elements studied. New calculations of the ionization cross section of Li and Na were performed in the framework of the Born-Bethe approximation as modified by Gaudin and Botter to take into account collisions with large momentum variation of the incident electron. Hartree-Fock type wave functions for the ground state atom (tabulated by Clementi) were used. The calculated values are in good agreement with our experimental results and with the former theoretical results calculated by various methods. This work also

  14. Half-metallic ferromagnetism in the CsSe compound by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Karaca, Mustafa; Kervan, Selçuk; Kervan, Nazmiye, E-mail: nkervan@gazi.edu.tr

    2015-08-05

    Graphical abstract: The ferromagnetic ground state of the CsSe compound is the most stable with CsCl-type structure with a total magnetic moment of 1 μ{sub B}/f.u. although this compound does not include transition metal atoms. The CsSe compound is half-metallic ferromagnet with a half-metallic band gap of 3.75 eV. The half-metallicity is also found to be robust with respect to the lattice distortion in the CsCl-type structure. The Curie temperature is estimated to be 390 K in the mean field approximation (MFA). - Highlights: • The CsSe compound is the most stable with CsCl-type structure. • The half-metallic band gap is about 3.5 eV for all types of structure. • The total magnetic moment is of 1 μ{sub B}/f.u. • The Curie temperature is estimated to be 390 K. - Abstract: The full-potential linearized augmented plane wave (FPLAPW) method based on the density functional theory is used to investigate the structural, magnetic and half-metallic properties of the CsSe compound in the CsCl-type, NaCl-type, ZnS-type, NiAs-type and wurtzite structures. The results show that the ferromagnetic ground state of the CsSe compound is the most stable with CsCl-type structure with a total magnetic moment of 1 μ{sub B}/f.u. although this compound does not include transition metal atoms. The CsSe compound is half-metallic ferromagnet for all types of structure. The half-metallic band gap is about 3.5 eV for all types of structure. The Curie temperature is estimated to be 390 K in the mean field approximation (MFA)

  15. Half-metallic ferromagnetism in the CsSe compound by density functional theory

    International Nuclear Information System (INIS)

    Graphical abstract: The ferromagnetic ground state of the CsSe compound is the most stable with CsCl-type structure with a total magnetic moment of 1 μB/f.u. although this compound does not include transition metal atoms. The CsSe compound is half-metallic ferromagnet with a half-metallic band gap of 3.75 eV. The half-metallicity is also found to be robust with respect to the lattice distortion in the CsCl-type structure. The Curie temperature is estimated to be 390 K in the mean field approximation (MFA). - Highlights: • The CsSe compound is the most stable with CsCl-type structure. • The half-metallic band gap is about 3.5 eV for all types of structure. • The total magnetic moment is of 1 μB/f.u. • The Curie temperature is estimated to be 390 K. - Abstract: The full-potential linearized augmented plane wave (FPLAPW) method based on the density functional theory is used to investigate the structural, magnetic and half-metallic properties of the CsSe compound in the CsCl-type, NaCl-type, ZnS-type, NiAs-type and wurtzite structures. The results show that the ferromagnetic ground state of the CsSe compound is the most stable with CsCl-type structure with a total magnetic moment of 1 μB/f.u. although this compound does not include transition metal atoms. The CsSe compound is half-metallic ferromagnet for all types of structure. The half-metallic band gap is about 3.5 eV for all types of structure. The Curie temperature is estimated to be 390 K in the mean field approximation (MFA)

  16. NEXAFS investigations of transition metal oxides, nitrides, carbides, sulfides and other interstitial compounds

    Science.gov (United States)

    Chen, J. G.

    Owing to their unique physical and chemical properties, transition metal compounds, especially transition metal oxides, nitrides, carbides and sulfides, have been the subject of many surface science investigations. In this article we will review applications of the near-edge X-ray absorption fine structure (NEXAFS) technique in the investigations of electronic and structural properties of transition metal compounds. This review covers NEXAFS studies of compounds in various physical forms, including bulk single crystals, well-characterized overlayers on surfaces of corresponding parent metals, and amorphous powder materials. In addition to transition metal oxides, nitrides, carbides and sulfides, we will also briefly discuss NEXAFS studies of interstitial compounds containing other 2p and 3p non-metal components, namely boron, fluorine, silicon, phosphorus and chlorine. We will discuss the correlation between experimental NEXAFS spectra and the local bonding environment of these compounds, such as the number of d-electrons, spin configurations, ligand-field splitting, coordination numbers, local symmetries, and crystal structures. In addition, NEXAFS investigations of the adsorption and reaction of probing molecules will also be discussed to reveal the underlying chemical reactivities of these materials. We will use many examples to demonstrate the importance of NEXAFS studies in the overall understanding of the physical and chemical properties of transition metal compounds. Finally, we will conclude this review by summarizing the current applications, as well as potential research opportunities, of NEXAFS in several technologically important research areas, including materials science, catalysis, biological science, earth science and environmental science.

  17. Alkali and alkaline earth metal salts of boron anionic complexes with o-hydroxy-benzyl alcohols (saligenin)

    International Nuclear Information System (INIS)

    Salts of two anionic boron complexes with 2 hydroxy-benzyl alcohol-[BA2- and [B(OH)2A]- - were synthesized. The first complex was separated in the form of anhydrous potassium and cesium salts, the second one - in the form of sodium (dihydrate), calcium (dihydrate) and barium (tetrahydrate and anhydrous salt) salts. Conditions of formation are discussed. Solubility in water and organic solvents, interplanar distances of crystal lattice were determined. The compounds were studied by the methods of infrared spectroscopy, thermal analysis. Hypothetical composition of the compounds is given

  18. Superconductivity in ternary iron pnictides: AFe2As2 (A = alkali metal) and LiFeAs

    International Nuclear Information System (INIS)

    Superconductivity is observed in AFe2As2 (A = Cs, Rb, K) at temperatures below 4 K. The metastable compound NaFe2As2 displays superconductivity with a high Tc=25K. These compounds are considered to be strongly hole-overdoped. The stoichiometric LiFeAs is superconducting below 18 K. The origin of superconductivity in LiFeAs is critically investigated and we show that Li deficiency cannot explain the experimental results. We propose that superconducting LiFeAs is stoichiometric and it is equivalent to the high-pressure state of other undoped iron pnictides.

  19. Superconductivity in ferromagnetic metals and in compounds without inversion centre

    OpenAIRE

    Mineev, V. P.

    2004-01-01

    The symmetry properties and the general overview of the superconductivity theory in the itinerant ferromagnets and in materials without space parity are presented. The basic notions of unconventional superconductivity are introduced in broad context of multiband superconductivity which is inherent property of ferromagnetic metals or metals without centre of inversion.

  20. Methods for synthesizing metal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-09

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

  1. Diode laser spectroscopy of NaD, KD, RbD, and CsD: determination of the mass independent parameters and mass scaling coefficients of the alkali metal hydrides

    International Nuclear Information System (INIS)

    The infrared spectrum of the monodeuterides of the alkali metals, sodium, potassium, rubidium, and cesium have been measured with a nominal accuracy of ±0.001 cm-1 using a diode laser spectrometer. Spectral lines of both the fundamental and the first hot band were observed for all the deuterides except RbD where only the fundamental was measured. The accuracy of previously published data on KH was also improved. Combination of these new data with similar results obtained previously for the equivalent monohydrides allowed the determination of a set of mass-independent parameters and mass-scaling coefficients for the hydrides of all of the alkali metals. This has allowed the relative magnitudes of the parameters to be compared for the first time. The results indicate that non-adiabatic effects are most prevalent in CsH. (orig.)

  2. Phosphorus-containing podands. 9. Synthesis of oligoethylene glycol bis(diphenylphospinylethyl) esters and their complexing properties with respect to alkali metal cations in a low-polarity solvent

    International Nuclear Information System (INIS)

    The complexing ability of phosphoryl-containing monopodands with the general formula Ph2P(O)CH2CH2O(CH2CH2O)nCH2CH2P(O)Ph2 (n = 0-5, 6.4, 8.7, 13.2) with respect to alkali metal cations was investigated conductometrically in tetrahydrofuran:chloroform mixed solvent (4:1, vol.) at 25 degrees C. It was found that ligands of this type are efficient complexing agents relative to all alkali metal cations, and the monopodand with n = 0 also exhibits elevated Li/Na and Li/K selectivity. The effect of the structure, particularly the rigidity of the terminal fragments of the monopodands, on their complexing capacity was discussed. The method of synthesis of this type of ligand was described. 12 refs., 1 fig., 3 tabs

  3. A Case Study of In Silico Modelling of Ciprofloxacin Hydrochloride/Metallic Compound Interactions

    OpenAIRE

    Stojkovic, Aleksandra; Parojcic, Jelena; Djuric, Zorica; Corrigan, Owen I.

    2013-01-01

    With the development of physiologically based absorption models, there is an increased scientific and regulatory interest in in silico modelling and simulation of drug–drug and drug–food interactions. Clinically significant interactions between ciprofloxacin and metallic compounds are widely documented. In the current study, a previously developed ciprofloxacin-specific in silico absorption model was employed in order to simulate ciprofloxacin/metallic compound interaction observed in vivo. C...

  4. Efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated ITO substrate and an electron-injection layer of alkali-metal carbonates

    International Nuclear Information System (INIS)

    The efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated substrate and an electron-injection layer of alkali-metal carbonates (Li2CO3 and Cs2CO3) was studied. The Li2CO3 and the Cs2CO3 carbonates were thermally evaporated to a thickness of 1 nm. For the device with a Li2CO3 layer, the luminance at 9.25 V of the device with the plasma-treated ITO substrate was found to be improved by approximately 10% compared to that of the device with the plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.0 V. For the device with a Cs2CO3 layer, the luminance at 11.25 V of the device with the oxygen plasma-treated ITO substrate was found to be improved by approximately 42.3% compared to that of the device with plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.25 V. Especially, the luminous efficiencies of the devices with the Li2CO3 and the Cs2CO3 layers were confirmed to have been increased by 50.0% and 78.1%, respectively, when the oxygen-plasma-treated ITO substrate was used.

  5. Milk-alkali syndrome

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000332.htm Milk-alkali syndrome To use the sharing features on this page, please enable JavaScript. Milk-alkali syndrome is a condition in which there ...

  6. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  7. Volatile Metals Coordination Compounds as Precursors for Functional Materials Synthesis by CVD-Method

    OpenAIRE

    Mazurenko, E.; Gerasimchuk, A.

    1995-01-01

    The applications of such coordination compounds (chelates) as metal β-diketonates in different CVD techniques were examined. It was shown that high chemical and physical characteristics of these compounds allow their favourable use comparatively with other volatile compounds. The general rules in volatility and thermal stability of β-diketonates and their fluorine derivatives were discussed. The ways of preparation of various functional materials with specific properties were determined.

  8. Composites for removing metals and volatile organic compounds and method thereof

    Science.gov (United States)

    Coronado, Paul R.; Coleman, Sabre J.; Reynolds, John G.

    2006-12-12

    Functionalized hydrophobic aerogel/solid support structure composites have been developed to remove metals and organic compounds from aqueous and vapor media. The targeted metals and organics are removed by passing the aqueous or vapor phase through the composite which can be in molded, granular, or powder form. The composites adsorb the metals and the organics leaving a purified aqueous or vapor stream. The species-specific adsorption occurs through specific functionalization of the aerogels tailored towards specific metals and/or organics. After adsorption, the composites can be disposed of or the targeted metals and/or organics can be reclaimed or removed and the composites recycled.

  9. Physicochemical aspects of inhibition of acid corrosion of metals by unsaturated organic compounds

    Science.gov (United States)

    Avdeev, Ya G.; Kuznetsov, Yurii I.

    2012-12-01

    The state-of-the-art in the development and improvement of methods for protecting metals from corrosion in mineral acid solutions using unsaturated organic compounds is considered. Characteristic features of the mechanism of their protective action on metal corrosion in acidic media are discussed. The bibliography includes 203 references.

  10. Metal fluorides

    International Nuclear Information System (INIS)

    Systems formed by fluorides of alkali, alkali earth, rare earth elements, yttrium, zirconium, hafnium, bismuth, antimony are investigated with the aim of preparing new fluoride materials and studying their thermodynamic and other physical and chemical properties. The respective phase diagrams are plotted. On the basis of the research fluoroberyllate glasses with rare earth additions of improved qualities (moisture resistance, crystallization resistance, resistance against radiation up to 100 Mrad) are prepared. The rho-T-x phase diagrams of the systems studied show that many compounds are sublimated congruently at certain temperatures and incongruently - above them. The existence of congruently sublimated compounds and azeotropically sublimated compositions provides for the preparation of uniform optical films. In connection with the search for new materials-luminophores and matrices of optical quantum generators - the fluoride systems of alkali metals and lanthanides are studied; the formation of binary fluorides of M3LnF6, M2LnF5, MLnF4, MLn2F7, MLn3F10 compositions is established. To search for new solid electrolytes, the solid-phase interaction of Sb-and Bi trifluorides with their oxides and alakali metal fluorides is studied. The electric conductivity of the compounds obtained is studied

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

    Czech Academy of Sciences Publication Activity Database

    Elicharová, Hana; Sychrová, Hana

    2014-01-01

    Roč. 160, č. 8 (2014), s. 1705-1713. ISSN 1350-0872 R&D Projects: GA ČR GAP302/12/1151; GA MŠk(CZ) ED1.1.00/02.0109 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : Candida glabrata * fluconazole * membrane potential Subject RIV: EE - Microbiology, Virology Impact factor: 2.557, year: 2014

  12. Single crystal growth of europium and ytterbium based intermetallic compounds using metal flux technique

    Indian Academy of Sciences (India)

    Sumanta Sarkar; Sebastian C Peter

    2012-11-01

    This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3 and Yb2AuGe3 compounds were obtained in high yield from the reactions of the elements in liquid indium. The results presented here demonstrate that considerable advances in the discovery of single crystal growth of complex phases are achievable utilizing molten metals as solvents.

  13. Electron dynamics of transition metal compounds studied with resonant soft X-ray scattering

    International Nuclear Information System (INIS)

    High resolution experimental data for resonant soft x-ray scattering of transition metal compounds are shown. The compounds studied are the ionic transition metal di-fluorides, ionic and covalent ortho vanadates and members of the La1-xSrxCoO3 perovskite family. In all compounds we studied the transition metal L2,3 edge and also the ligand (oxygen or fluorine) K edge. For the ionic compounds the transition metal data are in good agreement with atomic multiplet ligand field calculations that include charge transfer effects. Density functional calculations give very useful information to interpret the ligand x-ray emission data. The experimental metal Lα emission data show that the region between valence and conduction bands in the di-fluorides has several d-excited states. At the L2 edge of the ionic ortho vanadates we found the signature of a fast Coster-Kronig decay process that results in a very localized emission peak. Changes in the oxidation states in the La1-xSrxCoO3 compounds are observed at both the metal L2,3 edge and the oxygen K edge absorption spectra. (Author)

  14. Separation of stable isotopes of alkali and alkaline earth metals in chemical exchange systems with crown ethers

    International Nuclear Information System (INIS)

    Chemical isotope exchange in two-phase water - organic systems Men+ (water) - MeLn+ (org), where Me = Li, Ca, K, Mg; L = crown ethers with 5 to 6 oxygen atoms in macrocyclic ring; org = CHCl3, CH2Cl2 has been studied. The process of isotope separation has been realized by extraction chromatography. The chromatographic column contained a fixed aqueous phase. The organic solution of metal complex with crown ether was eluted through the column. On contact with the fixed aqueous phase in the course of chromatography, metal salt reextraction occurred and interphase isotope exchange between aqueous and organic phases resulted. Isotope separation factors in these systems were in the range of: 1.0032 - 1.020 (6Li/7Li), 1.0016 - 1.0038 (40Ca/44Ca), 1.0007 - 1.0011 (39K/41K), 1.0014 - 1.0044 (24Mg/26Mg). The theoretical model has been proposed to interpret the high separation factors in crown ether extraction systems. According to this model, the potential in such systems has a very flat bottom. This type of potential results in weakening the force field and decreasing of β-factor (i.e., (s/s')f) in spite of comparatively high energy of complexation. This model can interpret both high separation factors and their strong dependence on the type of crown ether. (author)

  15. The Systematic Study of the Organotransition Metal Compounds.

    Science.gov (United States)

    Carriedo, Gabino A.

    1990-01-01

    Discussed is an extension of the conventional method for studying the organometallic chemistry of transition metals that may be useful to show how the various existing types of low-valence complexes can be constructed. This method allows students to design new types of complexes that may still be nonexistent. (CW)

  16. Analysis on Alkali Metal Migration Law in Process of Eucalyptus Branches Direct Combustion%桉树枝直燃利用过程中碱金属迁移规律分析

    Institute of Scientific and Technical Information of China (English)

    韦威; 廖艳芬; 陈拓; 马晓茜; 杨云金; 余勇强

    2014-01-01

    For knowing alkali metal migration law in eucalyptus branches burned in some biomass power plant,this paper studies it by combustion experiment.The experimental sample is eucalyptus branch particle with grain size of 1 80μm which is used for repeat combustion experiment in pipe burner in order to get residual samples under different temperatures and with different combustion time.By proximate analysis on residual samples,it is able to get combustion laws of volatiles and fixed carbon.The experimental result shows that volatility of alkali metal in eucalyptus branches is very strong and there is 87%potassium released into gas phase in process of high temperature burning.Meanwhile,precipitation of alkali metal is speeding up with increase of temperature and precipitation volume dose is increasing with temperature and stop time.In addition,tak-ing kaolin as additive,it conducts quantitative analysis on its impact on retention rate of alkali metal in ash.The analysis re-sult indicates that kaolin has very good retention role for alkali metal in eucalyptus branches and retention effect of 5% kao-lin is the best.%为了解某生物质电厂燃用的桉树枝的碱金属迁移规律,对其进行了燃烧实验研究。实验样品为粒径180μm的桉树枝颗粒,在管式燃烧器中进行燃烧重复实验,获得不同温度和燃烧时间下的残留物样品,然后对残留物进行工业分析,获得挥发分、固定碳的燃烧规律;实验结果表明桉树枝碱金属挥发性很强,高温燃尽时有87%的钾释放进入气相,碱金属的析出随温度的增高而加快,析出总量也随温度和停留时间而增加。另外,以高岭土作为添加剂,定量分析了其对桉树枝碱金属在灰渣中的固留率的影响,分析结果表明高岭土对桉树枝的碱金属有很好固留作用,5%的高岭土添加量固留效果最佳。

  17. Electronic and thermodynamic properties of transition metal elements and compounds

    International Nuclear Information System (INIS)

    This thesis focuses on the use of band-structure calculations for studying thermodynamic properties of solids. We discuss 3d-, 4d- and 5d-transition metal carbides and nitrides. Through a detailed comparison between theoretical and experimental results, we draw conclusions on the character of the atomic bonds in these materials. We show how electronic structure calculations can be used to give accurate predictions for bonding energies. Part of the thesis is devoted to the application of the generalized gradient approximation in electronic structure calculations on transition metals. For structures with vibrational disorder, we present a method for calculating averaged phonon frequencies without using empirical information. For magnetic excitations, we show how a combined use of theoretical results and experimental data can yield information on magnetic fluctuations at high temperatures. The main results in the thesis are: Apart for an almost constant shift, theoretically calculated bonding energies for transition metal carbides and nitrides agree with experimental data or with values from analysis of thermochemical information. The electronic spectrum of transition metal carbides and nitrides can be separated into bonding, antibonding and nonbonding electronic states. The lowest enthalpy of formation for substoichiometric vanadium carbide VC1-X at zero temperature and pressure occurs for a structure containing vacancies (x not equal to 0). The generalized gradient approximation improves theoretical calculated cohesive energies for 3d-transition metals. Magnetic phase transitions are sensitive to the description of exchange-correlation effects in electronic structure calculations. Trends in Debye temperatures can be successfully analysed in electronic structure calculations on disordered lattices. For the elements, there is a clear dependence on the crystal structure (e.g., bcc, fcc or hcp). Chromium has fluctuating local magnetic moments at temperatures well above

  18. Synthesis and crystal structure of alkali metal uranium sulfides, Li2US3 and Na2US3

    International Nuclear Information System (INIS)

    New mixed uranium sulfides, A2US3 (A=Li,Na), in which uranium is in a tetravalent state, have been synthesized. In the disordered state, the compounds are written as A(A1/3,U2/3)S2 which have a hexagonal (R anti 3m) structure the same as the lanthanide homologue, ALnS2 (Ln=trivalent lanthanides). In the ordered state, the compounds take on a monoclinic (C2/m) structure in which the atom arrangement is very close to the above hexagonal structure. The partial ordering is realized by the coexistence of the two phases. The lattice parameters of hexagonal Li2US3 are a=3.898 and c=18.391 A, while those of monoclinic Li2US3 are a=6.747, b=11.679, c=6.537 A and β=110.2 . The lattice parameters of hexagonal Na2US3 are a=4.036 and c=19.780 A. Those of monoclinic Na2US3 are a=6.990, b=12.105, c=6.992 A and β=109.5 . The molar ratios of the hexagonal and monoclinic phases are 52.2:47.8 for Li2US3 and 68.0:32.0 for Na2US3, respectively. The atom parameters of uranium and sulfur were obtained by Rietveld calculation of the observed X-ray peaks. The atom separations are discussed in relation to the crystal radii of the component ions. (orig.)

  19. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites. PMID:20937860

  20. A structural investigation of the alkali metal site distribution within bioactive glass using neutron diffraction and multinuclear solid state NMR.

    Science.gov (United States)

    Martin, Richard A; Twyman, Helen L; Rees, Gregory J; Smith, Jodie M; Barney, Emma R; Smith, Mark E; Hanna, John V; Newport, Robert J

    2012-09-21

    The atomic-scale structure of Bioglass and the effect of substituting lithium for sodium within these glasses have been investigated using neutron diffraction and solid state magic angle spinning (MAS) NMR. Applying an effective isomorphic substitution difference function to the neutron diffraction data has enabled the Na-O and Li-O nearest-neighbour correlations to be isolated from the overlapping Ca-O, O-(P)-O and O-(Si)-O correlations. These results reveal that Na and Li behave in a similar manner within the glassy matrix and do not disrupt the short range order of the network former. Residual differences are attributed solely to the variation in ionic radius between the two species. Successful simplification of the 2 bioactive glasses, and an analogous splitting of the Li-O correlations. The observed correlations are attributed to the metal ions bonded either to bridging or to non-bridging oxygen atoms. (23)Na triple quantum MAS (3QMAS) NMR data corroborates the split Na-O correlations. The structural sites present will be intimately related to the release properties of the glass system in physiological fluids such as plasma and saliva, and hence to the bioactivity of the material. Detailed structural knowledge is therefore a prerequisite for optimizing material design. PMID:22868255

  1. Metal(loid)organic compounds in contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Hirner, A.V.; Grueter, U.M.; Kresimon, J. [Univ. of Essen (Germany). Inst. of Environmental Analytical Chemistry

    2000-10-01

    13 samples of soils contaminated with petrol, coaly residues, shredder and domestic waste have been investigated by low temperature gas chromatography with plasma mass spectrometry detection after sample derivatisation by hydride generation (HG/LT-GC/ICP-MS). 24 organic compounds of 9 elements could be analysed, one fifth of them exceeding the concentration of 1 {mu}g/kg. These results are roughly comparable with those on harbour and river sediments, and are discussed in respect to a preliminary evaluation of the emission potential of solid waste and contaminated soil as well as waste treatment processes. (orig.)

  2. Thermodynamic properties of two mixed alkali metal borates with NLO behaviour: Li6Rb5B11O22 and Li4Cs3B7O14

    International Nuclear Information System (INIS)

    Highlights: • Li6Rb5B11O22 and Li4Cs3B7O14 have been synthesized and characterized. • The enthalpies of solution of title two borates were measured. • The enthalpies of solution of LiCl·H2O(s) were measured. • ΔfHmo for title two borates were obtained by the thermochemical cycles. -- Abstract: Two pure mixed alkali metal borates with Non-Linear Optical (NLO) properties, Li6Rb5B11O22 and Li4Cs3B7O14, have been synthesized by a high-temperature solid state reaction, and characterized by XRD, FT-IR, DTA-TG techniques and chemical analysis. The molar enthalpies of solution of Li6Rb5B11O22 and Li4Cs3B7O14 in 1 mol · dm−3 HCl (aq), and of LiCl·H2O(s) in (1 mol · dm−3 HCl + H3BO3 + RbCl/CsCl) (aq) have been determined by microcalorimeter at T = 298.15 K, respectively. From these data and with the incorporation of the previously determined enthalpy of solution of H3BO3(s) in 1 mol · dm−3 HCl (aq), together with the use of the standard molar enthalpies of formation for LiCl·H2O(s), RbCl(s)/CsCl(s), H3BO3(s), HCl(aq) and H2O(l), the standard molar enthalpies of formation of −(11173.1 ± 9.5) kJ · mol−1 for Li6Rb5B11O22 and −(7145.1 ± 5.9) kJ · mol−1 for Li4Cs3B7O14 were obtained on the basis of the appropriate thermochemical cycles

  3. Crystalline and amorphous rare-earth metallic compounds

    International Nuclear Information System (INIS)

    During the last years the study of magnetic behaviour of rare-earth (or yttrium) compounds with cobalt and iron has growth of interest. This interest of justified by a large area of experimental and theoretical problems coming into being in the study of some rare-earth materials as well as in their technical applications. In the last three years a great number of new rare earth materials were studied and also new models explaining the magnetic behaviour of these systems have been used. In this paper we refer especially to some typical systems in order to analyse the magnetic behaviour of iron and cobalt and also the part played by the magnetic interactions in the values of the cobalt or iron moments. The model used will be generally the molecular field model. In the second chapter we present comparatively the structure of crystalline and amorphous compounds for further correlation with the magnetic properties. In chapter III we analyse the magnetic interactions in some crystalline and amorphous rare-earth alloys. Finally, we exemplify the ways in which we ensure better requried characteristics by the technical utilizations of these materials. These have in view the modifications of the magnetic interactions and are closely related with the analysis made in chapter III

  4. METALLIC COMPOUNDS IN THE PHASE OF THE RETICULATED IONIC POLYMERS

    Directory of Open Access Journals (Sweden)

    Vasilii Gutsanu

    2010-12-01

    Full Text Available Using the Mossbauer spectroscopy and other physical methods it was demonstrated the presence of different iron compounds like β-FeOOH, α-Fe2O3, and jarosite mineral type compounds: (R4N,H3O[Fe3(OH6(SO42] or coordination modes: {RCOO-Fe(L4-OOCR}1+, {R-CO2=Fe(X2=O2C-R}n, {R-COO-Fe(X4-OOC-R}n, and {(-NCH2CH2N-= Fe(X2 =(-NCH2CH2N-}, where X= H2O, OH-, SO42-., n= from 3- to 1+ in the ion-exchange resins (KU-2, AN-31, AV-17, Varian – AD, EDE-10P after the contact with sulphate of iron(III solutions at different conditions: type of solvent, temperature, air atmosphere. In special conditions the ultrafine superparamagnetic particles of Fe2O3 have been obtained

  5. New hypodiphosphates of the alkali metals: Synthesis, crystal structure and vibrational spectra of the hypodiphosphates(IV) M{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (M=Rb and Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Peng [Institut fuer Anorganische und Analytische Chemie der TU Clausthal, Paul-Ernst-Strasse 4, D-38678 Clausthal-Zellerfeld (Germany); Wiegand, Thomas; Eckert, Hellmut [Institut fuer Physikalische Chemie and Graduate School of Chemistry, Westfaelische Wilhelms-Universitaet Muenster, Corrensstr. 28/30, D-48149 Muenster (Germany); Gjikaj, Mimoza, E-mail: mimoza.gjikaj@tu-clausthal.de [Institut fuer Anorganische und Analytische Chemie der TU Clausthal, Paul-Ernst-Strasse 4, D-38678 Clausthal-Zellerfeld (Germany)

    2012-10-15

    The new hypodiphosphates(IV) Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (1) and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (2) were synthesized by soft chemistry reactions from aqueous solutions of hypophosphoric acid and the corresponding heavy alkali-metal carbonates. Their crystal structures were determined by single crystal X-ray diffraction. Both compounds crystallize isotypic in the triclinic space group P-1 with one formula unit in the unit cell. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units in staggered conformation for the P{sub 2}O{sub 6} skeleton and the corresponding alkali-metal cations. In the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} ion the hydrogen atoms are in a 'trans-trans' conformation. O{center_dot}H-O hydrogen bonds between the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups consolidate the structures into a three-dimensional network. The FT-Raman and {sup 31}P and {sup 1}H and MAS NMR spectra of the title compounds have been recorded and interpreted, especially with respect to their assignment to the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups. Thermogravimetric data of 2 have been interpreted in terms of a thermal decomposition model. - Graphical Abstract: The layered compounds Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] have been synthesized and investigated. Both crystallize isotypic. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units and the corresponding alkali-metal cations. Highlights: Black-Right-Pointing-Pointer Synthesis and single-crystal structure of new alkali hypodiphosphates. Black-Right-Pointing-Pointer Structures are characterized by [(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})]{sup 2-} units and M

  6. Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

    Science.gov (United States)

    Gauslaa, Yngvar; Yemets, Olena A; Asplund, Johan; Solhaug, Knut Asbjørn

    2016-01-15

    Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio. PMID:26437350

  7. Studies on unusually reactive metal powders. Preparation of new organometallic and organic compounds including potential new catalysts. Final report, July 1, 1980-December 31, 1984

    International Nuclear Information System (INIS)

    This research project was involved with the preparation and study of highly reactive metal powders prepared by the reduction of metal salts with alkali metals. Studies concentrated on nickel, copper, cadmium, uranium, iron, and magnesium. The nickel powders have been found to react rapidly with benzylic halides, and the resulting organonickel complexes yield dibenzyl. Aryl halides react rapidly with the nickel powders to produce biaryl compounds in high yields. Benzylic halides react with the nickel powders in the presence of acylhalides to produce benzyl ketones in high yields. Reactions of ROCOCOC1 and benzylic halides with nickel powders yield benzyl ketones. These reactions proceed with a wide variety of substituents on the phenyl ring of the benzylic halides. Highly reactive uranium has been prepared, and found to react with a variety of oxygen containing substrates, such as nitrobenzene to yield azo benzene. Highly reactive magnesium has opened up a totally new area of low temperature Grignard chemistry. The preparation of highly reactive copper has allowed the direct preparation of organocopper species directly from organic halides. 16 refs., 6 tabs

  8. Modeling of Intermetallic Compounds Growth Between Dissimilar Metals

    Science.gov (United States)

    Wang, Li; Wang, Yin; Prangnell, Philip; Robson, Joseph

    2015-09-01

    A model has been developed to predict growth kinetics of the intermetallic phases (IMCs) formed in a reactive diffusion couple between two metals for the case where multiple IMC phases are observed. The model explicitly accounts for the effect of grain boundary diffusion through the IMC layer, and can thus be used to explore the effect of IMC grain size on the thickening of the reaction layer. The model has been applied to the industrially important case of aluminum to magnesium alloy diffusion couples in which several different IMC phases are possible. It is demonstrated that there is a transition from grain boundary-dominated diffusion to lattice-dominated diffusion at a critical grain size, which is different for each IMC phase. The varying contribution of grain boundary diffusion to the overall thickening kinetics with changing grain size helps explain the large scatter in thickening kinetics reported for diffusion couples produced under different conditions.

  9. Heavy metal ion extraction of crownether compounds with supercritical CO2 fluid

    International Nuclear Information System (INIS)

    Benzocrownether-diarylethene derivatives (5BCD, 6BCD) were synthesized and utilized to extract metal ions into supercritical CO2. In order to enhance the CO2-phillicity and the extraction capability, synthesized compounds have both perfluoro unit and benzocrown moiety and were compared with dicyclohexano 18-crown-6(DC18C6). With minimal amount of water and counter ions such as perfluorooctanesulphonic acid or perfluorooctanic acid, their metal ion(Sr2+, Co+2, Na+) extraction efficiency was investigated. 5BCD, 6BCD showed more than 50% extraction for Sr+2, Na+ions and their extraction efficiency was better than that of DC18C6 compound

  10. Soft X-Ray Spectroscopic Study of Fullerene Based Transition-Metal Compounds and Related Systems

    OpenAIRE

    Qian, Limin

    2001-01-01

    This thesis addresses the electronic and geometric structures of fullerene based transition-metal compounds and other related systems. The formation of TixC60, VxC60 and NbxC60 compounds has been examined by X-ray photoelectron, soft X-ray absorption and emission and spectroscopy techniques, including resonant inelastic X-ray scattering (RIXS). The symmetry and character of the chemical bond of transition metal-fulleride has been determined. A related study of single-walled carbon nanotubes i...

  11. Development of an experimental protocol for uptake studies of metal compounds in adherent tumor cells

    OpenAIRE

    Egger, Alexander E.; Rappel, Christina; Jakupec, Michael A.; Hartinger, Christian G.; Heffeter, Petra; Keppler, Bernhard K.

    2009-01-01

    Cellular uptake is being widely investigated in the context of diverse biological activities of metal compounds on the cellular level. However, the applied techniques differ considerably, and a validated methodology is not at hand. Therefore, we have varied numerous aspects of sample preparation of the human colon carcinoma cell line SW480 exposed in vitro to the tumor-inhibiting metal complexes cisplatin and indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(iii)] (KP1019) prior to analy...

  12. Oligomer and mixed-metal compounds potential multielectron transfer catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rillema, D.P.

    1992-03-30

    Projects related to the design and characterization of multimetallic complexes has proceeded forward with a number of achievements. First, photoprocesses in hydrogel matrices lead to the conclusion that cationic metallochromophores could be ion exchanged into a hydrogel matrix ({kappa}-carageenan) and substantial photocurrents could be generated. Second, X-ray structures of Ru(bpy){sub 3}{sup 2+}, Ru(bpm){sub 3}{sup 2+} and Ru(bpz){sub 3}{sup 2+}, where bpy is 2,2{prime}-bipyridine, bpm is 2,2{prime}-bipyrimidine and bpz is 2,2{prime}-bipyrizine, were obtained and revealed similar Ru-N bond distances in each complex even though their {sigma}-donor and {pi}-acceptor character differ markedly. The structure parameters are expected to provide theoreticians with the information needed to probe the electronic character of the molecular systems and provide us with direction in our synthetic strategies. Third, a copper(I) complex was synthesized with a dimeric-ethane-bridged, 1,10-phenanthroline ligand that resulted in isolation of a bimetallic species. The copper(I) complex did luminesce weakly, suggesting that the dimer possesses potential electron transfer capability. Fourth, the photophysical properties of (Re(CO){sub 4}(L-L)){sup +}, where L-L = heterocyclic diimine ligands, and Pt(bph)X{sub 2}, where bph = the dianion of biphenyl and X = CH{sub 3}CN, py or ethylendiamine, displayed luminescence at high energy and underwent excited-state electron transfer. Such high energy emitters provide high driving forces for undergoing excited-state electron transfer. Fifth, both energy and electron transfer were observed in mixed-metal complexes bridged by 1,2-bis(2,2{prime}-bipyridyl-4{prime}-yl) ethane.

  13. The role of a solvent in synthesis of organometallic and metal-containing compounds by direct oxidation of metal

    International Nuclear Information System (INIS)

    Solubility of magnesium, zinc and cadmium iodides in some organic solvents at 293 K was determined to study the role of solvent in the synthesis of organometallic and metal-containing compounds by direct oxidation of metal in the medium of polar solvent. On the basis of comparison of the experimental data on solubility and published data on oxidation rate of magnesium, zinc and cadmium by halogenated hydrocarbons in polar solvents it was shown that solubility of the reaction products in the reactive mixture is not responsible for the process rate in the systems studied

  14. Influence of the alkali metal cation on the fragmentation of monensin in ESI-MS/MS Influência de cátions de metais alcalinos sobre a fragmentação de monensina em ESI-MS/MS

    OpenAIRE

    Norberto Peporine Lopes; Filipe Alexandre Almeida-Paz; Paul Jonathan Gates

    2006-01-01

    The MS/MS fragmentation of the alkali metal complexes of monensin A are studied. The increase in alkali metal ionic radii decreases the ability of the Grob-Wharton fragmentation mechanism to occur and reduces the overall degree of fragmentation. Conversely, the electronegativity of the metal cation is related to the number of fragment ions observed.O presente trabalho relata os estudos de fragmentação por espectrometria de massas seqüencial de complexos formados pela monensina A e uma série d...

  15. Structure and catalytic properties of metal β-diketonate complexes with oxygen-containing compounds

    International Nuclear Information System (INIS)

    The results of researches published in recent 15-20 years of complexes of metal β-diketonates (including Cr3+, VO2+, MoOΛ22+, Co3+, Mn3+, Ni2+, Fe3+) with oxygen-containing compounds (alcohols, glycols, phenols, hydroperoxides, aldehydes, esters, etc.) playing an important role in catalytic processes of oxidation, addition, polymerization and copolymerization are reviewed. Data on the nature of chemical bond of oxygen-containing reacting agents with metal β-diketonates, on structure of metal β-diketonate complexes with oxygen-containing reacting agents and thermodynamics of complexing as well as on activation of reacting agents in complexes and catalytic properties of metal β-diketonates are discussed. Stored materials make it possible to exercise directed control of metal β-diketonate activity

  16. Evidence of Production of Neutral Cl35 Atoms by the Cl35 (n, p)S35 Process in Alkali Metal Chlorides

    International Nuclear Information System (INIS)

    A number of investigations reported in the literature have shown that S35 produced by the Cl35 (n, p)S35 process in neutron-irradiated alkali metal halides may be separated as S= , SO=3 and SO=4 after the irradiated crystals are dissolved in aqueous solutions of the appropriate carriers. The relative amounts of the three chemical forms depend on the purity of the sample and the conditions of irradiation and analysis. Attempts to identify neutral S35 atoms among the products of the neutron irradiation have been limited by the fact that elemental sulphur is too insoluble to use as a carrier in aqueous solution and by the exchange and adsorption processes which interfere when heterogeneous extraction processes are used. However, we have observed chemical evidence for an S35 species with properties which might be expected for neutral monatomic sulphur. When vacuum-sublimed, neutron-irradiated KCl is dissolved in degassed 0.3N aqueous NaOH containing S=, SO=3 and SO=4 , analysis for the three species typically shows 90% of the S35 activity as S=, 7% as SO=3 and 3% as SO=4 . When an identical experiment is done in which the carriers are added to the 0.3N NaOH solution after adding the KCl the typical S35 yields are 30% S=, 30% SO3 and 40% SO=4. Thus some 60% of the S35 species found in the S=3 fraction when the KCl is dissolved in the presence of carriers is found as SO=4 and SO=3 when the carriers are added after dissolution of the KCl. Since monatomic sulphur is thermodynamically unstable in H2O with respect to oxidation (ΔF = -5900 kcal/mole for S + 4H2O → 3H2O → 3H2 + H2SO4), and since it would also be expected to exchange readily with S= carrier these results suggest that some 60% of the S35 may be present in the irradiated KCl crystals as neutral monatomic S. Similar evidence for neutral S35 atoms has been obtained from neutron-irradiated crystals of NaCl, RbCl and CsCl. The effects of S= carrier concentration at the time of dissolution and of gamma

  17. Structure, production and properties of high-melting compounds and systems (hard materials and hard metals)

    International Nuclear Information System (INIS)

    The report contains contributions by various authors to the research project on the production, structure, and physical properties of high-melting compounds and systems (hard metals and hard materials), in particular WC-, TaC-, and MoC-base materials. (GSCH)

  18. Technologies for Extracting Valuable Metals and Compounds from Geothermal Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Stephen [SIMBOL Materials

    2014-04-30

    Executive Summary Simbol Materials studied various methods of extracting valuable minerals from geothermal brines in the Imperial Valley of California, focusing on the extraction of lithium, manganese, zinc and potassium. New methods were explored for managing the potential impact of silica fouling on mineral extraction equipment, and for converting silica management by-products into commercial products.` Studies at the laboratory and bench scale focused on manganese, zinc and potassium extraction and the conversion of silica management by-products into valuable commercial products. The processes for extracting lithium and producing lithium carbonate and lithium hydroxide products were developed at the laboratory scale and scaled up to pilot-scale. Several sorbents designed to extract lithium as lithium chloride from geothermal brine were developed at the laboratory scale and subsequently scaled-up for testing in the lithium extraction pilot plant. Lithium The results of the lithium studies generated the confidence for Simbol to scale its process to commercial operation. The key steps of the process were demonstrated during its development at pilot scale: 1. Silica management. 2. Lithium extraction. 3. Purification. 4. Concentration. 5. Conversion into lithium hydroxide and lithium carbonate products. Results show that greater than 95% of the lithium can be extracted from geothermal brine as lithium chloride, and that the chemical yield in converting lithium chloride to lithium hydroxide and lithium carbonate products is greater than 90%. The product purity produced from the process is consistent with battery grade lithium carbonate and lithium hydroxide. Manganese and zinc Processes for the extraction of zinc and manganese from geothermal brine were developed. It was shown that they could be converted into zinc metal and electrolytic manganese dioxide after purification. These processes were evaluated for their economic potential, and at the present time Simbol

  19. A Initio Lcao Electronic Structure Calculations of Layered Transition Metal Compounds.

    Science.gov (United States)

    Dawson, William G.

    1987-09-01

    Available from UMI in association with The British Library. In this work the electronic structure of three systems of layered transition metal compounds are examined using an ab initio tight binding (LCAO) method using the Xalpha exchange/correlation approximation: group VI ditellurides, group IV trichalcogenides and quaternary copper oxide defect-perovskites. A chemical pseudopotential argument is presented in order to justify the use of a small basis set of atomic orbitals. The group VI transition metal compounds MoTe_2 and WTe _2 show strong metal-metal interactions and MoTe_2 undergoes an unusual phase transition with the lattice parameter perpendicular to the layers decreasing with increasing temperature. The group IV transition metal trichalcogenides provide a useful series for study due to their quasi-1-dimensional character and the occurrence of two closely related structural variants. The atypical compound ZrTe_3 is given special attention because of its apparent semimetallic nature. The final group of compounds studied are the high Tc superconducting ceramics Ba-La-Cu-O and Ba-Y-Cu-O. The technological importance of compounds with zero resistance and showing the Meissner effect (expelling magnetic fields) above liquid nitrogen temperatures and the, as yet, undefined nature of the mechanism of superconductivity stresses the need to carefully examine the electronic structure of these materials. The role of oxygen vacancies, the charge state of the copper ions and the possibility of structural phase transitions are some of the topics considered here. The use of an atomic-orbital basis allows a comparatively straightforward description of the chemical bonding in a crystal--especially useful when the unit cell contains a large number of atoms.

  20. New spintronic superlattices composed of half-metallic compounds with zinc-blende structure

    Science.gov (United States)

    Fong, C. Y.; Qian, M. C.

    2004-12-01

    The successful growth of zinc-blende half-metallic compounds, namely CrAs and CrSb, in thin film forms offers a new direction to search for novel spintronic materials. By using a well documented first-principles algorithm, the VASP code, we predict the electronic and magnetic properties of superlattices made of these exciting half-metallic materials. Not only are the superlattices constructed with two of the half-metallic compounds (CrAs/MnAs) but also they are modelled to combine with both a III-V (GaAs-MnAs/CrAs/GaAs) and a IV-IV (MnC/SiC) semiconductor. We investigate variable thicknesses for the combinations. For every case, we find the equilibrium lattice constant as well as the lattice constant at which the superlattice exhibits the half-metallic properties. For CrAs/MnAs, the half-metallic properties are presented and the magnetic moments are shown to be the sum of the moments for MnAs and CrAs. The half-metallic properties of GaAs-MnAs/CrAs/GaAs are found to be crucially dependent on the completion of the d-p hybridization. The magnetic properties of MnC/SiC are discussed with respect to the properties of MnC.

  1. New spintronic superlattices composed of half-metallic compounds with zinc-blende structure

    Energy Technology Data Exchange (ETDEWEB)

    Fong, C Y; Qian, M C [Department of Physics, University of California, Davis, CA 95616-8677 (United States)

    2004-12-08

    The successful growth of zinc-blende half-metallic compounds, namely CrAs and CrSb, in thin film forms offers a new direction to search for novel spintronic materials. By using a well documented first-principles algorithm, the VASP code, we predict the electronic and magnetic properties of superlattices made of these exciting half-metallic materials. Not only are the superlattices constructed with two of the half-metallic compounds (CrAs/MnAs) but also they are modelled to combine with both a III-V (GaAs-MnAs/CrAs/GaAs) and a IV-IV (MnC/SiC) semiconductor. We investigate variable thicknesses for the combinations. For every case, we find the equilibrium lattice constant as well as the lattice constant at which the superlattice exhibits the half-metallic properties. For CrAs/MnAs, the half-metallic properties are presented and the magnetic moments are shown to be the sum of the moments for MnAs and CrAs. The half-metallic properties of GaAs-MnAs/CrAs/GaAs are found to be crucially dependent on the completion of the d-p hybridization. The magnetic properties of MnC/SiC are discussed with respect to the properties of MnC.

  2. Hydrolytic stability of heavy metal compounds in fly ash of a heat power plant

    International Nuclear Information System (INIS)

    Ash and slag from solid fuels are utilized widely in building materials and road surfaces, and in agriculture for soil acidulation. For all these uses it is important to know the amount and form of heavy metal compounds contained in ash and their likely behavior when ash and slag wastes are utilized. Studying the behavior of heavy metals in ash residues at contact with water media is important also because, for most trace elements, the authors lack experimental data that would enable us to predict their behavior after prolonged storage and industrial utilization. The present paper describes a study of lixiviation (at various pH in static conditions) of heavy metals form fly ash obtained by burning Azeisk coal. Homogenized ash selected from electric filter sections 1-4 was used, which has the following composition (%): SiO2 59.8; Al2O3; Fe23O3 7.1; CaO 4.1; MgO 1.3; other 2.8. In a neutral medium, Ni, Cu, Zn, Pb, and Mn lixiviation was slight, amounting to 0.01-0.4%. During coal combustion, these elements apparently form compounds that are slightly soluble in water, although it is also possible that ash retains high adsorptivity for heavy metals. As a result, in these conditions the reverse process of sorption of heavy metals from the solution by fly ash is also possible, which would reduce the heavy metal concentration in the solution

  3. New spintronic superlattices composed of half-metallic compounds with zinc-blende structure

    International Nuclear Information System (INIS)

    The successful growth of zinc-blende half-metallic compounds, namely CrAs and CrSb, in thin film forms offers a new direction to search for novel spintronic materials. By using a well documented first-principles algorithm, the VASP code, we predict the electronic and magnetic properties of superlattices made of these exciting half-metallic materials. Not only are the superlattices constructed with two of the half-metallic compounds (CrAs/MnAs) but also they are modelled to combine with both a III-V (GaAs-MnAs/CrAs/GaAs) and a IV-IV (MnC/SiC) semiconductor. We investigate variable thicknesses for the combinations. For every case, we find the equilibrium lattice constant as well as the lattice constant at which the superlattice exhibits the half-metallic properties. For CrAs/MnAs, the half-metallic properties are presented and the magnetic moments are shown to be the sum of the moments for MnAs and CrAs. The half-metallic properties of GaAs-MnAs/CrAs/GaAs are found to be crucially dependent on the completion of the d-p hybridization. The magnetic properties of MnC/SiC are discussed with respect to the properties of MnC

  4. Influence of Magnetic Field on Properties of Cement Compound on the Base of Boron-Containing LRW

    Energy Technology Data Exchange (ETDEWEB)

    Varlakov, A. P.; Gorbunova, O. A.; Barinov, A. S.; Dmitriev, S. A.; Fedora, O. V.

    2003-02-25

    At present boron-containing LRW cementation is an actual objective. At traditional cementing the grout on the base of boron containing LRW does not only harden, but also even does not stiffen. To obtain a cement compound with satisfactory regulated properties, a number of additives, for example, alkali (to correct pH), hydroxide or calcium salts, alkali metal hydrosilicates are applied, which complicates technology and requires LRW chemical continuous composition control.

  5. Heavy-metal compounds in the environment of the Zagorsk pumped-storage station region

    International Nuclear Information System (INIS)

    The Zagorsk pumped-storage station (ZPSS) is being constructed in a rather developed area. Pollution of the environment by compounds of metals is, in particular, a consequence. The tasks of this investigation included: the establishment of the main sources of pollution of terrestrial and aquatic ecosystems by metal compounds in the region of construction of the ZPSS; determination of the level of content of these substances in various components of the landscape; and evaluation of the effect of regulating the Kun'ya River on processes of migration and accumulation of heavy metals in aquatic ecosystems. In conformity with these tasks, a comprehensive geochemical study was performed in 1990-1991 of the drainage basin of the Kun'ya River, the results of which are presented here. Samples were collected of soil, forest litter, snow, bottom sediments, and surface waters. The investigation showed that the main sources of pollution of the aquatic environment in the ZPSS construction region by heavy-metal compounds were surface runoff from developed territories and insufficiently treated industrial wastewaters. 5 refs., 2 figs., 4 tabs

  6. Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N-(2-Pyridylethyl)-N'-(2,6-diisopropylphenyl)pivalamidine.

    Science.gov (United States)

    Kalden, Diana; Oberheide, Ansgar; Loh, Claas; Görls, Helmar; Krieck, Sven; Westerhausen, Matthias

    2016-07-25

    N-(2,6-Diisopropylphenyl)-N'-(2-pyridylethyl)pivalamidine (Dipp-N=C(tBu)-N(H)-C2 H4 -Py) (1), reacts with metalation reagents of lithium, magnesium, calcium, and strontium to give the corresponding pivalamidinates [(tmeda)Li{Dipp-N=C(tBu)-N-C2 H4 -Py}] (6), [Mg{Dipp-N=C(tBu)-N-C2 H4 -Py}2 ] (3), and heteroleptic [{(Me3 Si)2 N}Ae{Dipp-N=C(tBu)-N-C2 H4 -Py}], with Ae being Ca (2 a) and Sr (2 b). In contrast to this straightforward deprotonation of the amidine units, the reaction of 1 with the bis(trimethylsilyl)amides of sodium or potassium unexpectedly leads to a β-metalation and an immediate deamidation reaction yielding [(thf)2 Na{Dipp-N=C(tBu)-N(H)}] (4 a) or [(thf)2 K{Dipp-N=C(tBu)-N(H)}] (4 b), respectively, as well as 2-vinylpyridine in both cases. The lithium derivative shows a similar reaction behavior to the alkaline earth metal congeners, underlining the diagonal relationship in the periodic table. Protonation of 4 a or the metathesis reaction of 4 b with CaI2 in tetrahydrofuran yields N-(2,6-diisopropylphenyl)pivalamidine (Dipp-N=C(tBu)-NH2 ) (5), or [(thf)4 Ca{Dipp-N=C(tBu)-N(H)}2 ] (7), respectively. The reaction of AN(SiMe3 )2 (A=Na, K) with less bulky formamidine Dipp-N=C(H)-N(H)-C2 H4 -Py (8) leads to deprotonation of the amidine functionality, and [(thf)Na{Dipp-N=C(H)-N-C2 H4 -Py}]2 (9 a) or [(thf)K{Dipp-N=C(H)-N-C2 H4 -Py}]2 (9 b), respectively, are isolated as dinuclear complexes. From these experiments it is obvious, that β-metalation/deamidation of N-(2-pyridylethyl)amidines requires bases with soft metal ions and also steric pressure. The isomeric forms of all compounds are verified by single-crystal X-ray structure analysis and are maintained in solution. PMID:27355970

  7. Crystal growth and evaluation of scintillation properties of Eu and alkali-metal co-doped LiSrAlF{sub 6} single crystals for thermal neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Wakahara, Shingo; Yokota, Yuui; Yamaji, Akihiro; Fujimoto, Yutaka; Sugiyama, Makoto; Kurosawa, Shunsuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Pejchal, Jan [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Kawaguchi, Noriaki [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fukuda, Kentaro [Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2012-12-15

    In recent work, Na co-doping have found to improve the light output of Eu doped LiCaAlF{sub 6} (Eu:LiCAF) for thermal neutron scintillator. We grew Eu 2% and alkali metal 1% co-doped LiSAF crystals by Micro-Pulling down method to understand the effect of alkali metal co-doping on scintillation properties and mechanism compared with LiCAF. In photo- and {alpha}-ray induced radio-luminescence spectra of the all grown crystals, the emissions from d-f transition of Eu{sup 2+} were observed. Without relation to excitation source, decay times of co-doped LiSAF were longer than Eu only doped one. The light yield of Na, K and Cs co-doped LiSAF under {sup 252}Cf neutron excitation were improved. Especially, K co-doped Eu:LiSAF reached 33200 ph/n, which outperformed Eu only doped one by approximately 20% (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Silica enigma and ignorance in alkali

    International Nuclear Information System (INIS)

    Si migration and K, Na alterations are two key problems for understanding the whole process of hydrothermal metallogenesis, but they have not attracted sufficient attention of geologists for a long time. It is impossible for us to know hydrothermal metallogenetic regularity actually without studying dequartzfication and alkali-introduction. Being distinct from common habitual thinking, it is considered that ore-forming elements are micro-amount, passive subordinate components in the flow of hydrothermal matter movement, and there is no metallogenesis for a certain element in nature. Except that the ore source is controlled by the uneven distribution ore-forming elements in the mantle and crust the same metallogenesis may almost lead to the formation of deposits of all elements. Principal active components in the hydrothermal matter system include alkali, silica and acid volatiles. The ternary system has determined the fate of release, activation, migration, precipitaion and concentration of ore-forming elements. Each member of the ternary system plays a different role in metallogenesis, having marvellous functional division of work. of these three members main control factor is alkali metal, whereas silica and acid are constrained by alkali. Acidic matter (including silica) and ore-forming elements are derivatives from activities of alkali metals

  9. New compounds of dysprosium. Some structural and gamma resonance characteristics

    International Nuclear Information System (INIS)

    Dysprosium compounds of different groups are synthesized. About ten phases undescribed in literature interpreted as double oxophosphates, oxosilicates, oxoborates and oxotungstates of dysprosium-alkali metal are registered according to X ray diffraction analysis data. NGR spectroscopy investigation into the compounds produced on 161Dy confirms the interpretation proposed and allows one to select the most perspective substances to conduct experiments on the search for spatial parity violation on dysprosium-161 nuclei. 13 refs., 1 fig., 2 tabs

  10. Oxidation of oil sulfur compounds to sulfones under foam-emulsion conditions in presence of metals

    International Nuclear Information System (INIS)

    Oxidation of sulfur compounds in diesel fraction, as well as of sulfoxide concentrate, by hydrogen peroxide to sulfones under foam-emulsion conditions in the presence of variable valency metal (V, Mo, W, Ti, Cr) compounds has been studied. It is ascertained that organic derivatives of molybdenum and vanadium are effective catalysts of sulfides to sulfones. The best results are obtained in the presence of water soluble ethylene glycolate of molybdenum. The mechanisms of chemical reactions occurring in the process is considered. Refs. 10

  11. Optical properties across the insulator to metal transitions in vanadium oxide compounds

    Energy Technology Data Exchange (ETDEWEB)

    Perucchi, A; Baldassarre, L [Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste (Italy); Postorino, P; Lupi, S, E-mail: andrea.perucchi@elettra.trieste.i [CNR-INFM Coherentia and Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Piazzale Aldo Moro 2, I-00185 Roma (Italy)

    2009-08-12

    We review the optical properties of three vanadium oxide compounds V{sub 2}O{sub 3}, VO{sub 2} and V{sub 3}O{sub 5}, belonging to the so-called Magneli phase. Their electrodynamics across a metal to insulator transition is investigated as a function of both temperature and pressure. We analyse thoroughly the optical results, with a special emphasis on the infrared spectral weight. This allows us to discuss the nature of the mechanisms driving the phase transitions in the three compounds, pointing out the role of electron-electron and electron-phonon interactions in the various cases. (topical review)

  12. Optical properties across the insulator to metal transitions in vanadium oxide compounds

    International Nuclear Information System (INIS)

    We review the optical properties of three vanadium oxide compounds V2O3, VO2 and V3O5, belonging to the so-called Magneli phase. Their electrodynamics across a metal to insulator transition is investigated as a function of both temperature and pressure. We analyse thoroughly the optical results, with a special emphasis on the infrared spectral weight. This allows us to discuss the nature of the mechanisms driving the phase transitions in the three compounds, pointing out the role of electron-electron and electron-phonon interactions in the various cases. (topical review)

  13. Optical properties across the insulator to metal transitions in vanadium oxide compounds.

    Science.gov (United States)

    Perucchi, A; Baldassarre, L; Postorino, P; Lupi, S

    2009-08-12

    We review the optical properties of three vanadium oxide compounds V(2)O(3), VO(2) and V(3)O(5), belonging to the so-called Magnéli phase. Their electrodynamics across a metal to insulator transition is investigated as a function of both temperature and pressure. We analyse thoroughly the optical results, with a special emphasis on the infrared spectral weight. This allows us to discuss the nature of the mechanisms driving the phase transitions in the three compounds, pointing out the role of electron-electron and electron-phonon interactions in the various cases. PMID:21693963

  14. Stability and electronic structure of Zr-based ternary metallic glasses and relevant compounds

    International Nuclear Information System (INIS)

    The electronic structure of the Zr-based metallic glasses has been investigated by theoretical and experimental approaches. One approach is band calculations of the Zr2Ni (Zr66.7Ni33.3) compound to investigate the electronic structure of the Zr66.7Ni33.3 metallic glass (ΔT x = 0 K) of which the local atomic structure is similar to that of the Zr2Ni compound. The other is photoemission spectroscopy of the Zr50Cu35Al15 bulk metallic glass (BMG) (ΔT x = 69 K). Here ΔT x = T x - T g where T x and T g are crystallization and glass transition temperature, respectively. Both results and previous ones on the Zr55Cu30Ni5Al10 BMG indicate that there is a pseudogap at the Fermi level in the electronic structure of these Zr-based metallic glasses, independent of the value of the ΔT x. This implies that the pseudogap at the Fermi level is one of the factors that stabilize the glass phase of Zr-based metallic glasses

  15. Generation, detection and characterization of gas-phase transition metal aggregates and compounds

    International Nuclear Information System (INIS)

    The goal of our research is to employ spectroscopic techniques to characterize the bound portions of the potential energy surface (PES) for chemical systems involving diatomic and triatomic transition metal molecules. The approach incorporates the generation and isolation of new metal compounds via supersonic laser ablation molecular beam techniques. Detection and characterization is achieved using high resolution dye laser induced fluorescence spectroscopy. A major objective is to produce information which can be compared to theoretical predictions and thereby provide guidelines and insight into the development of reaction models

  16. New quaternary compounds resulting from the reaction of copper and f-block metals in molten polychalcogenide salts at intermediate temperatures. Valence fluctuations in the layered CsCuCeS3

    International Nuclear Information System (INIS)

    From the reaction of elemental copper and either lanthanides or actinides in molten alkali metal/polychalcogenide salts, several new quaternary phases have been discovered. Specifically, these phases are ACuM2Q6(where A = K, M = La, Q =S: A = Cs, M = Ce, Q = S; or A = K, M = Ce, Q = Se) and ACuMQ3 (where A = Cs, M = Ce, Q = S; or A = K, M = U, Q = Se). The CsCuCe2S6 crystallizes in the orthorhombic space group Immm with a = 5.500-(1) Angstrom, b = 22.45(1) Angstrom, c = 4.205(4) Angstrom. The KCuCe2Se6 is isostructural. The CsCuCeS3 crystallizes in the orthorhombic space group Cmcm with a = 4.024(2) Angstrom, b = 15.154(2) Angstrom, c = 10.353(3) Angstrom. The KCuUSe3 is isostructural. In ACuM2Q6, the lanthanides bond to a mixture of mono- and disulfides in a bicapped trigonal prismatic geometry; these polyhedra subsequently connect in two dimensions, forming layers equivalent to those seen in the ZrSe3 structure type with Cu+ atoms residing in tetrahedral sites within the layers and alkali cations in the interlayer gallery. The compounds of the formula ACuMQ3 also possess a layered structure. Here the [MQ6] octahedral units form corrugated, two-dimensional sheets via edge-sharing in the first dimension and corner-sharing in the second. Copper cations are coordinated to tetrahedral sites in the folds of the corrugations, and alkali cations are again in the intergallery region. Detailed of the synthesis, structure, and properties of these compounds are discussed. 42 refs., 14 figs., 8 tabs

  17. Li2Sr4B12O23: A new alkali and alkaline-earth metal mixed borate with [B10O18]6− network and isolated [B2O5]4− unit

    International Nuclear Information System (INIS)

    A novel ternary lithium strontium borate Li2Sr4B12O23 crystal with size up to 20 mm×10 mm×4 mm has been grown via the top-seeded solution growth method below 730 °C. Single-crystal XRD analyses showed that Li2Sr4B12O23 crystallizes in the monoclinic space group P21/c with a=6.4664(4) Å, b=8.4878(4) Å, c=15.3337(8) Å, β=102.02(3)°, Z=2. The crystal structure is composed of [B10O18]6− network and isolated [B2O5]4− unit. The IR spectrum further confirmed the presence of both BO3 and BO4 groups. TG-DSC and Transmission spectrum were reported. Band structures and density of states were calculated. - Graphical abstract: A new phase, Li2Sr4B12O23, has been discovered in the ternary M2O–M′O–B2O3 (M=alkali-metal, M′=alkalineearth metal) system. The crystal structure consists of [B10O18]6− network and isolated [B2O5]4− unit. Highlights: ► Li2Sr4B12O23 is a a novel borate discovered in the M2O–M′O–B2O3 (M=alkali-metal, M′=alkaline-earth metal) system. ► Li2Sr4B12O23 crystal structure has a three-dimensional crystal structure with [B10O18]6− network and isolated [B2O5]4− unit. ► Sr1 and Sr2 are located in two different channels constructed by 3∞[B10O18] network.

  18. Simultaneous Synthesis of Dimethyl Carbonate and Poly(ethylene terephthalate) Using Alkali Metals as Catalysts%碱金属化合物催化同时合成碳酸二甲酯和聚对苯二甲酸乙二醇酯

    Institute of Scientific and Technical Information of China (English)

    张丹; 王庆印; 姚洁; 王越; 曾毅; 王公应

    2007-01-01

    Dimethyl carbonate (DMC) and poly(ethylene terephthalate) was simultaneously synthesized by the transesterification of ethylene carbonate (EC) with dimethyl terephthalate (DMT) in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carried out under the following conditions: the reaction temperature 250℃, molar ratio of EC to DMT 3: 1, reaction time 3h, and catalyst amount 0.004 (molar ratio to DMT), the yield of DMC was 68.9%.

  19. Directed reflectivity, long life AMTEC condenser (DRC). Final report of Phase II SBIR program[Alkali Metal ThermoElectric Converter

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, Thomas K.

    2001-09-10

    The Alkali Metal Thermal to Electric Converter (AMTEC) is a static energy conversion device that operates at high thermal to electric conversion efficiencies that are essentially independent of size, have reached 19% and are expected to reach 25% to 30% in 1997. AMTEC systems have been chosen by NASA and DOE for spacecraft applications and have considerable promise for a wide variety of terrestrial applications. Reduction of parasitic heat losses in AMTEC systems related to radiative heat transfer from the hot side to the condenser can make a substantial contribution to system efficiency. Through design, analysis and the fabrication and testing of cells and systems, the proposed program to develop a Directed Reflectivity Condenser (DRC) has investigated the feasibility of an improved AMTEC condenser component. Phase 1 work showed the potential for adding from 4% to 7% to overall system efficiency for identical operating conditions using the concept. A detailed thermal analysis of several DRC capped cell designs was carried out and some of the conditions under which a DRC, used as the condenser at an end cap of a cylindrical converter, can reduce thermal radiation related losses were determined. A model experimental converter was built and tested to compare DRC and planar condenser surfaces. The results of both analysis and experiment indicate that for moderate aspect ratios of a cylindrical, end condensed converter, the DRC can reduce overall thermal losses by up to 4%. The initial effort in Phase 2 extended the analysis to a novel 150 watt radial AMTEC cell design. This analysis indicated that for the effective aspect ratio of this new converter design, the system performance at the 100+ watt level was not significantly improved by use of a DRC type condenser surface. Further analyses however showed that for cylindrical, end-condensed converters, optimized for use with internal radiation shields, the use of DRC surfaces on the side walls of the converter could be

  20. Electrochemical decontamination of metallic wastes contaminated with uranium compounds in a neutral salt electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Choi, W. K.; Yang, Y. M.; Jung, C. H.; Won, H. J.; Oh, W. Z.; Park, J. H. [KAERI, Taejon (Korea, Republic of)

    2003-07-01

    Electrochemical decontamination process has been applied for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds such as UO{sub 2}, ammonium uranyl carbonate (AUC), ammonium di-uranate (ADU), and uranyl nitrate (UN) with tributylphosphate (TBP) and dodecane, which are generated by dismantling the contaminated system components and equipment of a retired uranium conversion plant in Korea Atomic Energy Research Institute (KAERI). Electrochemical decontamination for metallic wastes contaminated with uranium compounds was evaluated through the experiments on the electrolytic dissolution of stainless steel as the material of the system components in neutral concentration of electrolyte on the dissolution of the materials were evaluated. Decontamination performance tests using the specimens taken from a uranium conversion plant were quite successful with the application electrochemical decontamination conditions obtained through the basic studies on the electrolytic dissolution of structural material of the system components.

  1. Technology Development and Production of Certain Chemical Platinum Metals Compounds at JSC "Krastsvetmet"

    Institute of Scientific and Technical Information of China (English)

    ILYASHEVICH V.D.; PAVLOVA E.I.; KORITSKAYA N.G.; MAMONOV S.N.; SHULGIN D.R.; MALTSEV E.V.

    2012-01-01

    In recent years JSC "Krastsvetmet" has successfully developed the production of chemically pure compounds of precious metals.Currently methods have been developed and facilities have been provided for industrial production of the following platinum metals compounds:- Rhodium (Ⅲ) chloride hydrate,rhodium (Ⅲ) chloride solution,rhodium ( Ⅲ) nitrate solution,rhodium ( Ⅲ)iodide,rhodium ( Ⅲ) sulfate,hydrated rhodium ( Ⅲ) oxide,ammonium hexachlororodiate,rhodium ( Ⅲ)phosphate solution,rhodium electrolytes;Iridium (Ⅳ) chloride hydrate,iridium (Ⅲ) chloride hydrate,ammonium hexachloroiridate (Ⅳ),hexachloriridium acid solution,hexachloriridium crystalline acid;- Ruthenium (Ⅲ) chloride hydrate,ruthenium (Ⅳ) hydroxide chloride,ruthenium (Ⅳ) hydroxide chloride solution,ammonium hexachlororuthenate,ruthenium (Ⅲ) chloride solution,potassium,diaquaoctachloronitrido diruthenate.The quality of the production meets the requirements of Russian and foreign consumers.

  2. A standardized evaluation of artifacts from metallic compounds during fast MR imaging

    DEFF Research Database (Denmark)

    Murakami, Shumei; Verdonschot, Rinus G; Kataoka, Miyoshi;

    2016-01-01

    OBJECTIVE: Metallic compounds present in the oral and maxillofacial regions (OMR) cause large artifacts during MR scanning. We quantitatively assessed these artifacts embedded within a phantom according to standards set by the American Society for Testing and Materials (ASTM). MATERIALS AND METHODS...... according to the ASTM-F2119 standard and artifact volumes were assessed using OsiriX MD software Results: Tukey-Kramer post-hoc tests were used for statistical comparisons. For most materials, scanning sequences eliciting artifact volumes in the following (ascending) order FSE-T1/FSE-T2 ... plane (i.e. a circular pattern for axial plane and a "clover-like" pattern for sagittal plane). CONCLUSION: The availability of standardized information on artifact size and configuration during MR imaging will enhance diagnosis when faced with metallic compounds in the OMR....

  3. Electrochemical decontamination of metallic wastes contaminated with uranium compounds in a neutral salt electrolyte

    International Nuclear Information System (INIS)

    Electrochemical decontamination process has been applied for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds such as UO2, ammonium uranyl carbonate (AUC), ammonium di-uranate (ADU), and uranyl nitrate (UN) with tributylphosphate (TBP) and dodecane, which are generated by dismantling the contaminated system components and equipment of a retired uranium conversion plant in Korea Atomic Energy Research Institute (KAERI). Electrochemical decontamination for metallic wastes contaminated with uranium compounds was evaluated through the experiments on the electrolytic dissolution of stainless steel as the material of the system components in neutral concentration of electrolyte on the dissolution of the materials were evaluated. Decontamination performance tests using the specimens taken from a uranium conversion plant were quite successful with the application electrochemical decontamination conditions obtained through the basic studies on the electrolytic dissolution of structural material of the system components

  4. X-ray absorption to determine the metal oxidation state of transition metal compounds

    Science.gov (United States)

    Jiménez-Mier, J.; Olalde-Velasco, P.; Carabalí-Sandoval, G.; Herrera-Pérez, G.; Chavira, E.; Yang, W.-L.; Denlinger, J.

    2013-07-01

    We present three examples where x-ray absorption at the transition metal L2,3 edges is used to investigate the valence states of various strongly correlated (SC) and technological relevant materials. Comparison with ligand field multiplet calculations is needed to determine the metal oxidation states. The examples are CrF2, the La1-xSrxCoO3 family and YVO3. For CrF2 the results indicate a disproportionation reaction that generates Cr+, Cr2+ and Cr3+ in different proportions that can be quantified directly from the x-ray spectra. Additionally, it is shown that Co2+ is present in the catalytic La1-xSrxCoO3 perovskite family. Finally, surface effects that change the vanadium valence are also found in YVO3 nanocrystals.

  5. Apoptosis induction in human lymphocytes after in vitro exposure to cobalt/hard metal compounds

    International Nuclear Information System (INIS)

    Full text: An increased risk of lung cancer is associated with occupational exposure to mixtures of cobalt metal (Co) and tungsten carbide (WC) particles, but apparently not when exposure is to cobalt alone. The mechanism for this increased cancer risk is not fully understood. The evaluation of the in vitro genotoxic effects in lymphocytes exposed to varying cobalt species demonstrated that the WC-Co hard metal mixture is more genotoxic (DNA damage, chromosome/genome mutations) than metallic Co alone. WC alone was not genotoxic. Thus, WC-Co represents a specific (geno)toxic entity. In order to assess the survival of human lymphocytes after in vitro exposure to metallic Co, CoCl2, WC and the WC-Co mixture, two apoptosis/necrosis detection methods were applied (annexin V staining and flow cytometry). Annexin-V staining of early apoptotic cells demonstrated a dose- and time dependent induction of apoptosis by metallic Co, CoCl2, WC and the WC-Co mixture. The time course of the process varied according to the metal species tested. Metallic Co and CoCl2 caused a gradually increasing frequency of apoptotic cells with time (up to 24 h). WC-induced apoptosis displayed a typical 6 hour peak, which was not the case for the WC-Co mixture or for Co. Apoptosis induction by the WC-Co mixture was intermediate between that induced by Co and WC separately. Analysis of propidium iodide stained cells by flow cytometry was performed as a later marker for apoptosis induction. Preliminary data indicate similar tendencies of apoptosis induction as those detected by annexin-V. Identification of the apoptotic pathway triggered by the metal compounds was studied by inhibition of the ceramide-apoptosis pathway by fumonisin causing reduction of apoptosis induction for all compounds, but strongest after 6 hour exposure to WC. The use of specific caspase inhibitors will allow to further elucidate the different pathways involved. The current data demonstrating in vitro the apoptosis induction by

  6. Thermodynamic Properties and Mixing Thermodynamic Parameter of Binary Metallic Melt Involving Compound Formation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian

    2005-01-01

    Based on the coexistence theory of metallic melts involving compound formation,the theoretical cal culation equations of mixing thermodynamic parameters are established by giving up some empirical parameters in the associated solution model.For Fe-Al,Mn-Al and Ni-Al,the calculated results agree well with the experimental values,testifying that these equations can exactly embody mixing thermodynamic characteristics of these melts.

  7. μSR-studies of magnetic properties of metallic rare earth compounds

    International Nuclear Information System (INIS)

    Positive muons can probe the magnitude and the time dependence of the magnetic field at interstitial sites in condensed matter. Thus the relatively new techniques of muons spin rotation and muon spin relaxation have become unique tools for studying magnetism. After a brief introduction into the experimental method we then discuss measurements on the elemental rare earth metals and on intermetallic compounds, in particular on the cubic Laves phases REAl2

  8. Calculations of hyperfine interactions in transition metal compounds in the local density approximation

    International Nuclear Information System (INIS)

    A survey is made of some theoretical calculations of electrostatic and magnetic hyperfine interactions in transition metal compounds and complex irons. The molecular orbital methods considered are the Multiple Scattering and Discrete Variational, in which the local Xα approximation for the exchange interaction is employed. Emphasis is given to the qualitative informations, derived from the calculations, relating the hyperfine parameters to characteristics of the chemical bonds. (Author)

  9. Chemical shifts and EXAFS in some rare-earth metals and compounds

    International Nuclear Information System (INIS)

    The positions of the Lsub(111) absorption edge and accompanying Kossel and EXAFS oscillations of terbium, dysprosium and holmium in metals and compounds (acetate, carbonate, chloride, fluoride, nitrate, oxalate, oxide, phosphate and sulphate) have been measured. The chemical shifts of the main edge range from about 1 eV to about 10 eV and the EXAFS are observed up to about 150 eV. (author)

  10. Corrosion behavior of Zr(Fe, Cr)2 metallic compounds in 500 degree C superheated steam

    International Nuclear Information System (INIS)

    Zr(Fe, Cr)2 metallic compounds with different Fe/Cr ratio of 1.75 and 4.50 were prepared by non-consumable arc melting. X-ray diffraction, electron microprobe and transmission electron microscopy were employed for analyzing the corrosion products, the composition distribution and structure morphology after corrosion test of Zr(Fe, Cr)2 metallic compound powder at 500 degree C superheated steam with different exposure time. The corrosion products are the same for Zr(Fe, Cr)2 with different Fe/Cr ratio, but the corrosion resistant is better for Fe/Cr ratio of 1.75 than that of 4.50. Cubic ZrO2 and alpha Fe(Cr) are formed at the beginning of Zr(Fe, Cr)2 oxidation, then monoclinic ZrO2 transformed from cubic ZrO2 and (Fe, Cr)3O4 are observed at the late stage of oxidation. When the segregation of iron and chromium atoms occurs during the oxidation of Zr(Fe, Cr)2 metallic compounds, the diffusion rate of iron atoms is faster than that of chromium atoms. Based on the results obtained in present work, the effect of second phase particles on the corrosion behavior of Zircaloy-4 has been discussed

  11. Trivalent metal ions based on inorganic compounds with in vitro inhibitory activity of matrix metalloproteinase 13.

    Science.gov (United States)

    Wen, Hanyu; Qin, Yuan; Zhong, Weilong; Li, Cong; Liu, Xiang; Shen, Yehua

    2016-10-01

    Collagenase-3 (MMP-13) inhibitors have attracted considerable attention in recent years and have been developed as a therapeutic target for a variety of diseases, including cancer. Matrix metalloproteinases (MMPs) can be inhibited by a multitude of compounds, including hydroxamic acids. Studies have shown that materials and compounds containing trivalent metal ions, particularly potassium hexacyanoferrate (III) (K3[Fe(CN)6]), exhibit cdMMP-13 inhibitory potential with a half maximal inhibitory concentration (IC50) of 1.3μM. The target protein was obtained by refolding the recombinant histidine-tagged cdMMP-13 using size exclusion chromatography (SEC). The secondary structures of the refolded cdMMP-13 with or without metal ions were further analyzed via circular dichroism and the results indicate that upon binding with metal ions, an altered structure with increased domain stability was obtained. Furthermore, isothermal titration calorimetry (ITC) experiments demonstrated that K3[Fe(CN)6]is able to bind to MMP-13 and endothelial cell tube formation tests provide further evidence for this interaction to exhibit anti-angiogenesis potential. To the best of our knowledge, no previous report of an inorganic compound featuring a MMP-13 inhibitory activity has ever been reported in the literature. Our results demonstrate that K3[Fe(CN)6] is useful as a new effective and specific inhibitor for cdMMP-13 which may be of great potential for future drug screening applications. PMID:27542739

  12. Strongly correlated transition metal compounds investigated by soft X-ray spectroscopies and multiplet calculations

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez-Mier, J., E-mail: jimenez@nucleares.unam.mx [Instituto de Ciencias Nucleares, UNAM, 04510 México, DF (Mexico); Olalde-Velasco, P. [Instituto de Ciencias Nucleares, UNAM, 04510 México, DF (Mexico); The Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (United States); Herrera-Pérez, G.; Carabalí -Sandoval, G. [Instituto de Ciencias Nucleares, UNAM, 04510 México, DF (Mexico); Chavira, E. [Instituto de Investigaciones en Materiales, UNAM, 04510 México, DF (Mexico); Yang, W.-L.; Denlinger, J. [The Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (United States)

    2014-10-15

    Direct probe of Mott–Hubbard (MH) to charge-transfer (CT) insulator transition in the MF{sub 2} (M = Cr–Zn) family of compounds was observed by combining F K and M L X-ray emission spectra (XES). This transition is evident as a crossover of the F-2p and M-3d occupied states. By combining F K XES data with F K edge X-ray absorption (XAS) data we directly obtained values for the M-3d Hubbard energy (U{sub dd}) and the F-2p to M-3d charge-transfer energy (Δ{sub CT}). Our results are in good agreement with the Zaanen–Sawatzky–Allen theory. We also present three examples where X-ray absorption at the transition metal L{sub 2,3} edges is used to study the oxidation state of various strongly correlated transition metal compounds. The metal oxidation state is obtained by direct comparison with crystal field multiplet calculations. The compounds are CrF{sub 2}, members of the La{sub 1−x}Sr{sub x}CoO{sub 3} family, and the MVO{sub 3} (M = La and Y) perovskites.

  13. APPLICABILITY OF THE MASS ACTION LAW IN COMBINATION WITH THE COEXISTENCE THEORY OF METALLIC MELTS INVOLVING COMPOUND TO BINARY METALLIC MELTS

    Institute of Scientific and Technical Information of China (English)

    J. Zhang

    2002-01-01

    Based on the atomicity and molecularity as well as the consistency of thermodynamicproperties and activities of metallic melts with their structures, the coexistence the-ory of metallic melts structure involving compound has been suggested. According tothis theory, the calculating models of mass action concentrations for different binarymetallic melts have been formulated. The calculated mass action concentrations agreewell with corresponding measured activities, which confirms that the suggested theorycan reflect the structural characteristics of metallic melts involving compound and thatthe mass action law is widely applicable to this kind of metallic melts.

  14. Evolution of phenolic compounds and metal content of wine during alcoholic fermentation and storage.

    Science.gov (United States)

    Bimpilas, Andreas; Tsimogiannis, Dimitrios; Balta-Brouma, Kalliopi; Lymperopoulou, Theopisti; Oreopoulou, Vassiliki

    2015-07-01

    Changes in the principal phenolic compounds and metal content during the vinification process and storage under modified atmosphere (50% N2, 50% CO2) of Merlot and Syrah wines, from grapes cultivated in Greece, have been investigated. Comparing the variation of metals at maceration process, with the variation of monomeric anthocyanins and flavonols, an inverse relationship was noticed, that can be attributed to complexing reactions of polyphenols with particular trace elements. Cu decreased rapidly, whereas a similar behavior that could be expected for Fe and Mn was not confirmed. Differences in the profile of anthocyanins and flavonols in the fresh Merlot and Syrah wines are reported. During 1 year of storage monomeric anthocyanins declined almost tenfold, probably due to polymerization reactions and copigmentation. Also, a decrease in flavonol glycosides and increase in the respective aglycones was observed, attributed to enzymatic hydrolysis. The concentration of total phenols and all metals remained practically constant. PMID:25704697

  15. Safety Evaluation of Osun River Water Containing Heavy Metals and Volatile Organic Compounds (VOCs) in Rats.

    Science.gov (United States)

    Azeez, L; Salau, A K; Adewuyi, S O; Osineye, S O; Tijani, K O; Balogun, R O

    2015-01-01

    This study evaluated the pH, heavy metals and volatile organic compounds (VOCs) in Osun river water. It also evaluated its safety in rats. Heavy metals were determined by atomic absorption spectrophotometry (AAS) while VOCs were determined by gas chromatography coupled with flame ionization detector (GC-FID). Male and female rats were exposed to Osun river water for three weeks and then sacrificed. The abundance of heavy metals in Osun river followed the trend Pb > Cd > Zn > Fe > Cr > Cu while VOCs followed the trend benzene water for three weeks had increased WBC, thiobarbituric acid reactive substances (TBARS), serum proteins and serum aminotransferases. There were also significant decreases in HCT, PLT, liver aminotransferases and liver glutathione compared to the control. These results show that the pollutants in Osun river water are capable of inducing hematological imbalance and liver cell injury. The toxicity induced in blood was sex-dependent affecting female rats more than male rats. PMID:27506174

  16. Studies about interaction of hydrogen isotopes with metals and intermetallic compounds

    International Nuclear Information System (INIS)

    Hydrogen is a nontoxic but highly inflammable gas. Compared to other inflammable gasses, its range of inflammability in air is much broader (4-74.5%) but it also vaporizes much more easily. Handling of hydrogen in form of hydrides enhances safety. Experiments with gaseous and liquid hydrogen should be performed in rooms with good ventilation. The interaction of hydrogen with metals and intermetallic compounds is a major field within physical chemistry. The essential feature of hydrogen-element system consists in the formation of chemical bond between hydrogen and metal atoms. The study of the interactions of hydride-forming metals and intermetallic compounds with heavy hydrogen isotopes -deuterium and tritium- offers new possibilities for investigating hydrogen behavior on surfaces and in a solid matrix. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing systems, can solve many problems arising in the nuclear-fuel cycle. The Nuclear Power Plant Cernavoda is equipped with a Canadian reactor of CANDU type. In the long term, Cernavoda area will be contaminated with on increasing quantity of tritium. In addition, the continuous contamination of heavy water from the reactor reduces the moderator's efficiency. For these reasons, ICSI - Rm. Valcea has developed a detritiation technology, based on catalytic isotopic exchange and cryogenic distillation. Tritium should be removed from the tritiated heavy water, and this will require the storage of tritium in a special vessel that can provide a high level of protection and safety of environment and personnel. Several metals have been studied as storage beds for hydrogen isotopes. One of the reference materials used for storing of hydrogen isotopes is uranium, a material with a great storage capacity, but unfortunately it is a radioactive metal and can react with the impurities in the stored gas. Other metals and alloys as ZrCo, Ti

  17. Impact of metal-induced degradation on the determination of pharmaceutical compound purity and a strategy for mitigation.

    Science.gov (United States)

    Dotterer, Sally K; Forbes, Robert A; Hammill, Cynthia L

    2011-04-01

    Case studies are presented demonstrating how exposure to traces of transition metals such as copper and/or iron during sample preparation or analysis can impact the accuracy of purity analysis of pharmaceuticals. Some compounds, such as phenols and indoles, react with metals in the presence of oxygen to produce metal-induced oxidative decomposition products. Compounds susceptible to metal-induced decomposition can degrade following preparation for purity analysis leading to falsely high impurity results. Our work has shown even metals at levels below 0.1 ppm can negatively impact susceptible compounds. Falsely low results are also possible when the impurities themselves react with metals and degrade prior to analysis. Traces of metals in the HPLC mobile phase can lead to chromatographic artifacts, affecting the reproducibility of purity results. To understand and mitigate the impact of metal induced decomposition, a proactive strategy is presented. The pharmaceutical would first be tested for reactivity with specific transition metals in the sample solvent/diluents and in the HPLC mobile phase. If found to be reactive, alternative sample diluents and/or mobile phases with less reactive solvents or addition of a metal chelator would be explored. If unsuccessful, glassware cleaning or sample solution refrigeration could be investigated. By employing this strategy during method development, robust purity methods would be delivered to the quality control laboratories, preventing future problems from potential sporadic contamination of glassware with metals. PMID:21163601

  18. Alternative alkali resistant deNO{sub x} technologies. Appendix 1

    Energy Technology Data Exchange (ETDEWEB)

    Putluru, S.S.R.; Degn Jensen, A.

    2011-07-01

    The increased use of biomass as fuel has created some new challenges to establish SCR flue gas treatment technology. One of these challenges comes from biomass complex chemical composition, which includes potassium shown to have a negative impact on the SCR catalyst. Studies have shown that potassium deactivates SCR catalyst and reduces its ability to reduce NO to N{sub 2}. An attempt was made to protect the SCR catalyst from alkali poisoning by the imposition of a coating on the catalyst surface. Various compounds were coated on a commercial catalyst supplied by Haldor Topsoee A/S and tested for alkali poisoning resistance. These materials were broadly divided as metal oxides, zeolites and other materials. The coated catalysts were exposed to potassium chloride aerosols at 350 deg. C for 650-1200 h. SCR activity, SEM and EDX measurements were performed to analyze the coated catalysts resistance to potassium poisoning. Coated catalysts (Mg, Mg containing compounds and Zeolites) showed appreciable alkali resistivity compared to the uncoated reference catalyst. Coated catalysts showed high potassium concentration at the surface of the coating and low potassium concentration across the cross section when compared to the uncoated reference catalyst. Thus, it is assumed that the coating layer accumulates the potassium at the surface and prevents to penetrate through the catalyst. The overall assessment is that it is possible to protect an SCR catalyst from potassium poisoning by the imposition of coating layer. (Author)

  19. Study of reactions of metals with sulphur and phosphorus compounds by pulsed temperatures

    International Nuclear Information System (INIS)

    The anti-wear action of sulphur and phosphorus compounds which are usually added to gear-oils depends on chemical reactions with the metallic surfaces of the gears. These reactions occur both at the bulk oil temperature (approx. 100°C) and during high temperatures (approx. 600°C) of short duration when the gearteeth come into contact under lead. The temperature flashes were simulated in an apparatus in which short pulses of electric current were used to heat metal wires immersed in mineral oil containing S35 and P32 labelled compounds in solution. The radioactivity acquired by the wires was measured. The extent of the reactions was determined as a function of temperature and time and the results were interpreted in terms of conventional kinetic laws. The modification of the reaction rates by the presence of other compounds in the solution was studied. The effect of pre-formed surface films containing sulphur phosphorus, chlorine and/or oxygen was also determined. In explaining the results, the structure of the materials used and the diffusion processes whereby the reactions occur beyond the initial stages were considered. (author)

  20. Thermochemistry of some binary lead and transition metal compounds by high temperature direct synthesis calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Meschel, S.V., E-mail: meschel@jfi.uchicago.edu [Illinois Institute of Technology,Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, Illinois 60615 (United States); Gordon Center for Integrated Science, 929 E. 57th Street, Chicago, Illinois 60637 (United States); Nash, P. [Illinois Institute of Technology,Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, Illinois 60615 (United States); Chen, X.Q.; Wei, P. [Materials processing Modeling Division, Shenyang National Laboratory for Materials Science, Institute of Metals Research, 72 Wenhua Road, Shenyang City (China)

    2015-06-05

    Highlights: • Studied binary lead-transition metal alloys by high temperature calorimetry. • Determined the enthalpies of formation of 8 alloys. • Compared the measurements with predictions by the model of Miedema and by the ab initio method. - Abstract: The standard enthalpies of formation of some binary lead and transition metal compounds have been measured by high temperature direct synthesis calorimetry. The reported results are: Pb{sub 3}Sc{sub 5}(−61.3 ± 2.9); PbTi{sub 4}(−16.6 ± 2.4); Pb{sub 3}Y{sub 5}(−64.8 ± 3.6); Pb{sub 3}Zr{sub 5}(−50.6 ± 3.1); PbNb{sub 3}(−10.4 ± 3.4); PbRh(−16.5 ± 3.3); PbPd{sub 3}(−29.6 ± 3.1); PbPt(−34.7 ± 3.3) kJ/mole of atoms. We will compare our results with previously published measurements. We will also compare the experimental measurements with enthalpies of formation of transition metal compounds with elements in the same vertical column in the periodic table. We will compare our measurements with predicted values on the basis of the semi empirical model of Miedema and coworkers and with ab initio values when available.

  1. Photo-induced charge-orbital switching in transition-metal compounds probed by photoemission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Takubo, K; Mizokawa, T [Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, Kashiwa, Chiba 277-8561 (Japan); Takubo, N; Miyano, K [Research Center for Advanced Science and Technology (RCAST), University of Tokyo, Tokyo 153-8904 (Japan); Matsumoto, N; Nagata, S, E-mail: takubo@sces.k.u-tokyo.ac.j [Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido, 050-8585 Japan (Japan)

    2009-02-01

    Transition-metal compounds with spin, charge, and orbital degrees of freedom tend to have frustrated electronic states coupled with local lattice distortions and to show drastic response to external stimuli such as photo-excitation. We have studied the charge-orbital states in perovskite-type Pr{sub 0.55}(Ca{sub 1-y}Sr{sub y}){sub 0.45}MnO{sub 3} thin films (PCSMO) and spinel-type CuIr{sub 2}S{sub 4} using photoemission spectroscopy combined with additional laser illumination. PCSMO and CuIr{sub 2}S{sub 4} are clear-cut examples of transition-metal compounds showing photo-induced metallic conductivities but the charge-orbital states in the two systems show contrasting responses to the photo-excitation. The charge-orbital states in PCSMO are stabilized by Jahn-Teller or Breathing-type lattice distortions and can be destroyed by photo-excitation. On the other hand, the charge-orbital states in CuIr{sub 2}S{sub 4} are stabilized by dimer formation and tend to be robust against photo-excitation.

  2. Thermochemistry of some binary lead and transition metal compounds by high temperature direct synthesis calorimetry

    International Nuclear Information System (INIS)

    Highlights: • Studied binary lead-transition metal alloys by high temperature calorimetry. • Determined the enthalpies of formation of 8 alloys. • Compared the measurements with predictions by the model of Miedema and by the ab initio method. - Abstract: The standard enthalpies of formation of some binary lead and transition metal compounds have been measured by high temperature direct synthesis calorimetry. The reported results are: Pb3Sc5(−61.3 ± 2.9); PbTi4(−16.6 ± 2.4); Pb3Y5(−64.8 ± 3.6); Pb3Zr5(−50.6 ± 3.1); PbNb3(−10.4 ± 3.4); PbRh(−16.5 ± 3.3); PbPd3(−29.6 ± 3.1); PbPt(−34.7 ± 3.3) kJ/mole of atoms. We will compare our results with previously published measurements. We will also compare the experimental measurements with enthalpies of formation of transition metal compounds with elements in the same vertical column in the periodic table. We will compare our measurements with predicted values on the basis of the semi empirical model of Miedema and coworkers and with ab initio values when available

  3. Theoretical assessment of the electro-optical features of the group III nitrides (B12N12, Al12N12 and Ga12N12) and group IV carbides (C24, Si12C12 and Ge12C12) nanoclusters encapsulated with alkali metals (Li, Na and K)

    Science.gov (United States)

    Tahmasebi, Elham; Shakerzadeh, Ehsan; Biglari, Zeinab

    2016-02-01

    Density functional theory (DFT) calculations have been carried out to study the influence of alkali metals (Li, Na and K) encapsulation within the group III nitrides (B12N12, Al12N12 and Ga12N12) and the group IV carbides (C24, Si12C12and Ge12C12) nanoclusters. The encapsulation of Li, Na and K atoms is found to narrow the HOMO-LUMO gaps of the considered clusters. The electronic properties of these clusters, especially the group III nitrides nanoclusters, are strongly sensitive to interaction with the alkali metals. Moreover it is observed that the encapsulation of alkali metals enhances the first hyperpolarizabilities of B12N12 nanocluster. Surprisingly, due to the alkali metals encapsulation within B12N12 nanocluster, the first hyperpolarizability values are remarkably increased to 8505.49 and 122,503.76 a.u. for Na@B12N12 and K@B12N12, respectively. Also the TD-DFT calculations at both CAM-B3LYP/6-311+G(d) and PBE0/6-311+G(d) levels of theory are also performed to investigate the origin of first hyperpolarizabilities.

  4. Effects of alkali treatments on Ag nanowire transparent conductive films

    Science.gov (United States)

    Kim, Sunho; Kang, Jun-gu; Eom, Tae-yil; Moon, Bongjin; Lee, Hoo-Jeong

    2016-06-01

    In this study, we employ various alkali materials (alkali metals with different base strengths, and ammonia gas and solution) to improve the conductivity of silver nanowire (Ag NW)-networked films. The alkali treatment appears to remove the surface oxide and improve the conductivity. When applied with TiO2 nanoparticles, the treatment appears more effective as the alkalis gather around wire junctions and help them weld to each other via heat emitted from the reduction reaction. The ammonia solution treatment is found to be quick and aggressive, damaging the wires severely in the case of excessive treatment. On the other hand, the ammonia gas treatment seems much less aggressive and does not damage the wires even after a long exposure. The results of this study highlight the effectiveness of the alkali treatment in improving of the conductivity of Ag NW-networked transparent conductive films.

  5. Ab initio study of the adsorption, diffusion, and intercalation of alkali metal atoms on the (0001) surface of the topological insulator Bi{sub 2}Se{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ryabishchenkova, A. G., E-mail: ryaange@gmail.com; Otrokov, M. M.; Kuznetsov, V. M.; Chulkov, E. V. [Tomsk State University (Russian Federation)

    2015-09-15

    Ab initio study of the adsorption, diffusion, and intercalation of alkali metal adatoms on the (0001) step surface of the topological insulator Bi{sub 2}Se{sub 3} has been performed for the case of low coverage. The calculations of the activation energies of diffusion of adatoms on the surface and in van der Waals gaps near steps, as well as the estimate of diffusion lengths, have shown that efficient intercalation through steps is possible only for Li and Na. Data obtained for K, Rb, and Cs atoms indicate that their thermal desorption at high temperatures can occur before intercalation. The results have been discussed in the context of existing experimental data.

  6. Influence of the alkali metal cation on the fragmentation of monensin in ESI-MS/MS Influência de cátions de metais alcalinos sobre a fragmentação de monensina em ESI-MS/MS

    Directory of Open Access Journals (Sweden)

    Norberto Peporine Lopes

    2006-09-01

    Full Text Available The MS/MS fragmentation of the alkali metal complexes of monensin A are studied. The increase in alkali metal ionic radii decreases the ability of the Grob-Wharton fragmentation mechanism to occur and reduces the overall degree of fragmentation. Conversely, the electronegativity of the metal cation is related to the number of fragment ions observed.O presente trabalho relata os estudos de fragmentação por espectrometria de massas seqüencial de complexos formados pela monensina A e uma série de metais alcalinos. Foi observado que o aumento do raio iônico do metal alcalino levou a uma diminuição do mecanismo de fragmentação do tipo Grob-Wharton e ao grau de fragmentação. Por outro lado, a maior eletronegatividade mostrou estar relacionada ao número de fragmentos observados.

  7. Ballmilling of metal borohydrides for hydrogen storage

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    ’s dehydrogenated state. Specifically, the research undertaken targets CaB6 whose boron is in a octahedral network, or AlB2 whose boron is layered. These compounds were then reactive ball milled with alkali and alkaline earth metal under hydrogen pressure, with the intention of forming metal borohydrides. For CaB6...... investigation is to hydrogenate simple compounds such as metalborides and hydrides with the intention of forming a new and more hydrogen rich borohydride. In contrast to mainstream research, the method of synthesis has been based on reactants that are expected to be found in the metal borohydride...

  8. Optical Parameters and Absorption of Azo Dye and Its Metal-Substituted Compound Thin Films

    Institute of Scientific and Technical Information of China (English)

    魏斌; 吴谊群; 顾冬红; 干福熹

    2003-01-01

    We determine the complex refractive indices N ( N = n - ik), dielectric constants ε(ε = ε1 - iε2), and absorption coefficients α of a new azo dye [2-(6-methyl-2-benzothiazolyazo)-5-diethylaminophenol(MBADP)]-doped polymer and its nickel- and zinc-substituted compounds(Ni-MBADP and Zn-MBADP) spin-coated thin films from a scanning ellipsometer in the wavelength 400-700 nm region. Metal chelation strongly (about one times) enhances the optical and dielectric parameters at the peaks and results in a large bathochromic shift (50-60nm) of absorption band. Bathochromic shift of Ni-MBADP is about 10nm larger than that of Zn-MBADP due to different spatial configurations formed in the metal-azo complexes.

  9. Influence of main-group element on half-metallic properties in half-Heusler compound

    Science.gov (United States)

    Liu, Hongyan; Li, Yushan; Tian, Fuyang; Li, Getian

    2016-04-01

    We investigate the band structure, magnetism and density of states of half-Heusler compounds CoCrZ (Z = Si,Ge,P,As) based on the first-principle calculations. Combined with molecular orbital hybridization theory, we discuss the influence of the main-group element on half-metallic properties of CoCrZ. It is found that the replacement of Ge for Si in CoCrSi can adjust the position of the Fermi level, and while it has no impact on the energy gap width and magnetic structure. However, the substitution of P for Si can effectively adjust the magnetism without disrupting its half-metallicity. Our results demonstrate that the electronic structure of CoCrZ is mainly dependent on the number of valence electrons of the main-group element.

  10. Enhancement of nonlinear optical properties of compounds of silica glass and metallic nanoparticle

    Indian Academy of Sciences (India)

    GHARAATI A; KAMALDAR A

    2016-06-01

    The aim of this paper is to introduce a method for enhancing the nonlinear optical properties in silica glass by using metallic nanoparticles. First, the T-matrix method is developed to calculate the effective dielectric constant for the compound of silica glass and metallic nanoparticles, both of which possess nonlinear dielectric constants. In the second step, the Maxwell–Garnetttheory is exploited to replace the spherical nanoparticles with cylindrical and ellipsoidal ones, facilitating the calculation of the third-order nonlinear effective susceptibility for a degenerate four-wave mixing case. The results are followed by numerical computations for silver, copper and gold nanoparticles. It is shown, graphically, that the maximum and minimum of the real part of thereflection coefficient for nanoparticles of silver occurs in smaller wavelengths compared to that of copper and gold. Further, it is found that spherical nanoparticles exhibit greater figure-of-merit compared to those with cylindrical or ellipsoidal geometries.

  11. Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

    Science.gov (United States)

    Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

    2016-01-01

    In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

  12. Alkalis and Skin.

    Science.gov (United States)

    Greenwood, John E; Tan, Jin Lin; Ming, Justin Choong Tzen; Abell, Andrew D

    2016-01-01

    The aim of this editorial is to provide an overview of the chemical interactions occurring in the skin of our patients on contact with alkaline agents. Strongly basic alkali is highly aggressive and will readily hydrolyze (or cleave) key biological molecules such as lipids and proteins. This phenomenon is known as saponification in the case of lipids and liquefactive denaturation for peptides and proteins. A short section on current first-aid concepts is included. A better understanding of the basic science behind alkali burns will make us better teachers and provide an insight into the urgency needed in treating these common and dangerous chemical injuries. PMID:26182072

  13. Incorporating functional groups on the structure of Acrylic fibers for adsorption of metal ionic compounds

    International Nuclear Information System (INIS)

    Common commercial acrylic fibers were modified by incorporating different suitable ion adsorbing functional groups into their structures. To study the ion adsorption ability of modified fibers against ionic compounds, the raw fibers were treated with hydroxylamine, hydrazine and urea. The new incorporated functional groups were characterized and appropriate formula for each reaction was suggested. In order to evaluate the ion adsorption capacity of the system, the modified fibers were immersed in separated metal salt solutions. The results show that the samples modified by hydroxylamine, have higher adsorption capacity than others, however, by pretreatment with hydrazine or urea not only the functional groups were increased but also the efficiency of the adsorption was improved

  14. On features of metal and binary compound sputtering by low-energy ions

    International Nuclear Information System (INIS)

    Molecular dynamic simulation has been used to study how the characteristics of metal and binary compound sputtering change under the bombardment by different low-energy ions. The influence of the target parameters on the anomalous mass dependence of sputtering yield has been investigated, both for targets with similar and very different values of density, the lattice constant and the surface binding energy. Together with the ratio of the target atoms' mass to the mass of the ions, the density of the target and the binding energy turn out to be the important parameters that determine the unusual shape of the mass dependence of sputtering by low-energy ions.

  15. On features of metal and binary compound sputtering by low-energy ions

    Energy Technology Data Exchange (ETDEWEB)

    Zykova, E.Yu. [Physics Faculty, Moscow State University, 119992 Moscow (Russian Federation)], E-mail: zykova@rambler.ru; Yurasova, V.E.; Elovikov, S.S. [Physics Faculty, Moscow State University, 119992 Moscow (Russian Federation)

    2009-08-15

    Molecular dynamic simulation has been used to study how the characteristics of metal and binary compound sputtering change under the bombardment by different low-energy ions. The influence of the target parameters on the anomalous mass dependence of sputtering yield has been investigated, both for targets with similar and very different values of density, the lattice constant and the surface binding energy. Together with the ratio of the target atoms' mass to the mass of the ions, the density of the target and the binding energy turn out to be the important parameters that determine the unusual shape of the mass dependence of sputtering by low-energy ions.

  16. Micro- and Nanostructured Metal Oxide Chemical Sensors for Volatile Organic Compounds

    Science.gov (United States)

    Alim, M. A.; Penn, B. G.; Currie, J. R., Jr.; Batra, A. K.; Aggarwal, M. D.

    2008-01-01

    Aeronautic and space applications warrant the development of chemical sensors which operate in a variety of environments. This technical memorandum incorporates various kinds of chemical sensors and ways to improve their performance. The results of exploratory investigation of the binary composite polycrystalline thick-films such as SnO2-WO3, SnO2-In2O3, SnO2-ZnO for the detection of volatile organic compound (isopropanol) are reported. A short review of the present status of the new types of nanostructured sensors such as nanobelts, nanorods, nanotube, etc. based on metal oxides is presented.

  17. Non-traditional metal electrode materials in electrochemical nvironmental analysis of biologically active compounds

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Šestáková, Ivana

    Tenerife: WSEAS, 2007 - (Otesteanu, M.; Celikyay, S.; Mastorakis, N.; Lache, S.; Benra, F.), s. 181-185 ISBN 978-960-6766-20-6. [WSEAS International Conference on ENVIRONMENT, ECOSYSTEMS and DEVELOPMENT (EED'07) /5./. Tenerife (ES), 14.12.2007-16.12.2007] R&D Projects: GA ČR GA203/07/1195; GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : metal electrode materials * biologically actove compounds * electrochemistry Subject RIV: CG - Electrochemistry

  18. Evolution of metal-compound residues on the walls of plasma etching reactor and their effect on critical dimensions of high-k/metal gate

    International Nuclear Information System (INIS)

    It was found that critical dimensions of high-k/metal gates obey the multivariate linear approximation with the precision of 3σ=±0.86 nm, whose explanatory variables are amounts of metal compounds remaining on the plasma reactor walls. To measure their amounts, the authors assumed they are proportional to amounts of atoms sputtered out by Ar plasma and falling onto a Si wafers placed on a wafer stage. In this study, effects of metal compounds of W, Ti, Ta, and Hf, which are used to construct full-metal/high-k gates, were measured. It was found that Ti and Ta compounds dominate the fluctuation of critical dimensions and the dependency of their amount on wafer numbers being etched obeys a simple difference equation. From these results, they can estimate and minimize the fluctuations of critical dimensions in mass fabrications.

  19. Some reduced ternary and quaternary oxides of molybdenum. A family of compounds with strong metal-metal bonds

    International Nuclear Information System (INIS)

    Several new, reduced ternary and quaternary oxides of molybdenum are reported, each containing molybdenum in an average oxidation state 2 sealed in Mo tubes held at 11000C for ca. 7 days. Refinement of the substructure of the new compound Ba062Mo4O6 was based on an orthorhombic cells, with a = 9.509(2), b = 9.825(2), c = 2.853(1) A, Z = 2 in space group Pbam; weak supercell reflections indicate the true structure has c = 8(2.853) A. The chief structural feature is closely related to that of NaMo4O6 which consists of infinite chains of Mo6 octahedral clusters fused on opposite edges, bridged on the outer edges by O atoms and crosslinked by Mo-O-Mo bonding to create four-sided tunnels in which the Ba2+ ions are located. The structure of Ba113Mo8O16 is triclinic, a = 7.311(1), b = 7.453(1), c = 5.726(1) A, α = 101.49(2), β = 99.60(2), γ = 89.31(2)0, Z = 1, space group P1. It is a low-symmetry, metal-metal bonded variant of the hollandite structure, in which two different infinite chains, built up from Mo4O82- and Mo4O8026- cluster units, respectively, are interlinked via Mo-O-Mo bridge bonding to create again four-sided tunnels in which the Ba2+ ions reside. Other compounds prepared and characterized by analyses and x-ray powder diffraction data are Pb/sub x/Mo4O6 (x approx. 0.6), LiZn2Mo3O8, , CaMo5O8, K2Mo12O19, and Na2Mo12O19

  20. Rydberg Matter clusters of alkali metal atoms: the link between meteoritic matter, polar mesosphere summer echoes (PMSE), sporadic sodium layers, polar mesospheric clouds (PMCs, NLCs), and ion chemistry

    CERN Document Server

    Olofson, Frans; Holmlid, Leif

    2010-01-01

    A material exists which links together the influx of meteoritic matter from interplanetary space, the polar mesosphere summer echoes (PMSE), the sporadic sodium layers, the polar mesospheric clouds (PMCs, NLCs), and the observed ion chemistry in the mesosphere. The evidence in these research fields is here analyzed and found to agree well with the properties of Rydberg Matter (RM). This material has been studied with numerous methods in the laboratory. Alkali atoms, mainly Na, reach the mesosphere in the form of interplanetary (meteoritic, cometary) dust. The planar RM clusters NaN usually contain N = 19, 37 or 61 atoms, and have the density of air at 90 km altitude where they float. The diameters of the clusters are 10-100 nm from laboratory high precision radio frequency spectroscopic studies. Such experiments show that RM clusters interact strongly with radar frequencies: this explains the radio frequency heating and reflection studies of PMSE layers. The clusters give the low temperature in the mesosphere...