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Sample records for lithium fluoride crystals

  1. Luminescence from Edge Fracture in Shocked Lithium Fluoride Crystals

    SciTech Connect

    Turley, W. D.; Stevens, G. D.; Capelle, G. A.; Grover, M.; Holtkamp, D. B.; LaLone, B. M.; Veeser, L. R.

    2013-01-01

    Light emitted from a [100] lithium fluoride crystal was characterized under shock wave compression to 28GPa followed by complete stress release at the edges. The light was examined using time-gated optical spectrometry and imaging, time-resolved optical emission measurements, and hydrodynamic modeling. The shock arrival at the circumference of the crystal was delayed relative to the center so that the two regions could be studied at different times. The majority of the light emission originated when the shock waves released at the circumference of the crystal. Unlike previously reported results for shocked lithium fluoride, we found that the light spectrum is not strictly broad band, but has spectral lines associated with atomic lithium in addition to a broad band background. Also, the emission spectrum depends strongly on the gas surrounding the sample. Based on our observations, the line emission appears to be related to fracture of the lithium fluoride crystal from the shock wave releasing at the edges. Experimenters frequently utilize lithium fluoride crystals as transparent windows for observing shock compressed samples. Because of the experimental geometries used, the shock wave in such cases often reaches the circumference of the window at nearly the same moment as when it reaches the center of the sample-window interface. Light generated at the circumference could contaminate the measurement at the interface when this light scatters into the observed region. This background light may be reduced or avoided using experimental geometries which delay the arrival of the shock wave at the edges of the crystal.

  2. Void control in the crystallization of lithium fluoride

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Perry, William D.

    1991-01-01

    The effect of tungsten-coated graphite fibers on the radiant heat transfer characteristics of salt-fiber composites was studied by measuring the onset of melting as a function of applied furnace power. As the fiber concentration was increased from 0 to 5.40 percent fiber by weight, the furnace temperature required to melt the lithium fluoride also increased. Upon cooling, each of the crystalline salt-fiber composites were cut open with a diamond saw to expose the void. Optical photographs of the voids revealed a trend in void location and size, with the largest void, and the least change in the outer dimension of the boule upon cooling, occurring in the sample with the most fiber.

  3. Shock Induced Birefringence in Lithium Fluoride

    SciTech Connect

    Holmes, N C

    2001-06-01

    We have used an ellipsometer to measure the birefringence of lithium fluoride in shock compression experiments. In previous x-ray diffraction experiments, single crystal [100] LiF has been reported to remain cubic at moderate pressures.

  4. Factors Affecting the Plasticity of Sodium Chloride, Lithium Fluoride, and Magnesium Oxide Single Crystals. 1

    NASA Technical Reports Server (NTRS)

    Stearns, Carl A.; Pack, Ann E.; Lad, Robert A.

    1959-01-01

    A study was made of the relative magnitude of the effects of various factors on the ductility of single crystals of sodium chloride (NaCl), lithium fluoride (LiF), and magnesium oxide (MgO). Specimen treatments included water-polishing, varying cleavage rate, annealing, quenching, X-irradiation, surface coating, aging, and combinations of some of these treatments. The mechanical behavior of the crystals was studied in flexure and in compression, the latter study being performed at both constant strain rate and constant load. Etch-pit studies were carried out to provide some pertinent information on the results of pretreatment on the dislocation concentration and distribution in the vicinity of the surface. The load deformation curves for these ionic single crystals show an initial region of very low slope which proved to be due to anelastic deformation. The extent of initial anelastic deformation is modified by specimen pretreatment in a way that suggests that this deformation is the result of expansion of cleaved-in dislocation loops, which can contract on the removal of the stress. The effects of the various pretreatments on the load and deflection at fracture are in accord with the prediction one might make with regard to their effect on the nucleation of fatal surface cracks. For NaCl, increases in ductility are always accompanied by increases in strength. The creep constants for NaCl are a function of treatments which affect the bulk structure but are not a function of treatments which only affect the surface.

  5. Studies of the optical spectra and spin-Hamiltonian parameters for the trivalent ytterbium ions in lithium yttrium fluoride crystals

    NASA Astrophysics Data System (ADS)

    Feng, W. L.; Han, Z.; Zhong, Y. C.

    In this paper, the crystal field (CF) levels and spin-Hamiltonian (SH) parameters (g factors g∥ and g⊥ and hyperfine structure constants A∥ and A⊥) of the rare-earth ion Yb3+ in lithium yttrium fluoride crystals are calculated under D2d point symmetry assumption. Two main methods are used in the calculation to study the SH parameters: one is the perturbation theory method and the other is the complete diagonalization (energy matrix) method (CDM). Comparing the calculated results with the experimental data, we can see that the CDM is more effective to calculate the SH parameters. In addition, the CF J-mixing of all excited-state multiplets into the ground-state multiplet 2F7/2 is considered. The validity of the calculated results is discussed.

  6. Fabrication of Optoelectronic Devices in Lithium Fluoride Crystals by Interfering Femtosecond Laser Pulses

    NASA Astrophysics Data System (ADS)

    Kurobori, Toshio; Obayashi, Yoshihiro; Suzuki, Kenji; Hirose, Yukio; Sakai, Toshiaki; Aoshima, Shin-ichiro

    2008-01-01

    Fine-pitched microgratings either on or beneath surface of bulk lithium fluoride (LiF) are holographically fabricated by interfering with the second harmonic (400 nm) of a mode-locked Ti:sapphire oscillator-amplifier laser. The laser-active F2 and F3+ color centers in LiF are excellent candidates for producing visible laser action from the green-to-red spectral range when excited with a single wavelength. Here a green distributed feedback (DFB) laser action with a narrower oscillating linewidth is demonstrated by utilizing simultaneous formation of the F3+ color centers and waveguide with the microgratings encoded by interference of 400 nm femtosecond laser pulses. In addition, the possibility of a dual-beam DFB laser based on these color centers in LiF is discussed.

  7. Optical spectroscopy and microscopy of radiation-induced light-emitting point defects in lithium fluoride crystals and films

    NASA Astrophysics Data System (ADS)

    Montereali, R. M.; Bonfigli, F.; Menchini, F.; Vincenti, M. A.

    2012-08-01

    Broad-band light-emitting radiation-induced F2 and F3+ electronic point defects, which are stable and laser-active at room temperature in lithium fluoride crystals and films, are used in dosimeters, tuneable color-center lasers, broad-band miniaturized light sources and novel radiation imaging detectors. A brief review of their photoemission properties is presented, and their behavior at liquid nitrogen temperatures is discussed. Some experimental data from optical spectroscopy and fluorescence microscopy of these radiation-induced point defects in LiF crystals and thin films are used to obtain information about the coloration curves, the efficiency of point defect formation, the effects of photo-bleaching processes, etc. Control of the local formation, stabilization, and transformation of radiation-induced light-emitting defect centers is crucial for the development of optically active micro-components and nanostructures. Some of the advantages of low temperature measurements for novel confocal laser scanning fluorescence microscopy techniques, widely used for spatial mapping of these point defects through the optical reading of their visible photoluminescence, are highlighted.

  8. Optical characterization of femtosecond laser induced active channel waveguides in lithium fluoride crystals

    SciTech Connect

    Chiamenti, I.; Kalinowski, H. J.; Bonfigli, F.; Montereali, R. M.; Gomes, A. S. L.; Michelotti, F.

    2014-01-14

    We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10{sup −3} to 10{sup −4} depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths.

  9. Fabrication of nanoscale patterns in lithium fluoride crystal using a 13.5 nm Schwarzschild objective and a laser produced plasma source

    SciTech Connect

    Wang Xin; Mu Baozhong; Jiang Li; Zhu Jingtao; Yi Shengzhen; Wang Zhanshan; He Pengfei

    2011-12-15

    Lithium fluoride (LiF) crystal is a radiation sensitive material widely used as EUV and soft x-ray detector. The LiF-based detector has high resolution, in principle limited by the point defect size, large field of view, and wide dynamic range. Using LiF crystal as an imaging detector, a resolution of 900 nm was achieved by a projection imaging of test meshes with a Schwarzschild objective operating at 13.5 nm. In addition, by imaging of a pinhole illuminated by the plasma, an EUV spot of 1.5 {mu}m diameter in the image plane of the objective was generated, which accomplished direct writing of color centers with resolution of 800 nm. In order to avoid sample damage and contamination due to the influence of huge debris flux produced by the plasma source, a spherical normal-incidence condenser was used to collect EUV radiation. Together with a description of experimental results, the development of the Schwarzschild objective, the influence of condenser on energy density and the alignment of the imaging system are also reported.

  10. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

    Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.

  11. Glycine lithium nitrate crystals

    NASA Astrophysics Data System (ADS)

    González-Valenzuela, R.; Hernández-Paredes, J.; Medrano-Pesqueira, T.; Esparza-Ponce, H. E.; Jesús-Castillo, S.; Rodriguez-Mijangos, R.; Terpugov, V. S.; Alvarez-Ramos, M. E.; Duarte-Möller, A.

    Crystals of glycine lithium nitrate with non-linear optical properties have been grown in a solution by slow evaporation at room temperature. The crystal shows a good thermal stability from room temperature to 175 °C where the crystal begins to degrade. This property is desirable for future technological applications. Also, a good performance on the second harmonic generation was found, characterizing the emitted dominant wavelength by a customized indirect procedure using luminance and chromaticity measured data based on the CIE-1931 standard. Additionally, the 532 nm signal was detected by using a variant to the Kurtz and Perry method.

  12. Fluoride laser crystals: old and new

    NASA Astrophysics Data System (ADS)

    Jenssen, Hans P.; Cassanho, Arlete

    2006-02-01

    The development of oxide and fluoride materials as gain materials of choice for solid state lasers ranges from early materials such as Calcium Fluoride and Calcium Tungstate crystals to the now ubiquitous Nd hosts YLF, YAG and Vanadate. Among Tunable laser materials, MgF II - an early favorite, gave way to superior oxides such as Alexandrite and Ti:Sapphire only to be followed by development of still newer tunable fluoride media, notably, fluoride colquiriites such as Cr-doped LiSAF and LiCaF. Newer fluoride crystals, such as Barium Yttrium Fluoride BaY II F 8 (BYF), KY 3F 10 (KYF) and the tunable Cr doped LiCaGaF 6 are attractive laser materials, but their growth has not been optimized. Key advantages of two of these new crystals are discussed. Crystal growth results for BYF and Cr:LiCaGaF 6 as well as some material characterization are presented.

  13. Compression of lithium fluoride to 92 GPa

    NASA Astrophysics Data System (ADS)

    Dong, Haini; Dorfman, Susannah M.; Holl, Christopher M.; Meng, Yue; Prakapenka, Vitali B.; He, Duanwei; Duffy, Thomas S.

    2014-01-01

    The equation of state and compression behavior of lithium fluoride, LiF, have been determined to 92 GPa by X-ray diffraction in a diamond anvil cell. A neon pressure-transmitting medium was used to minimize the effect of differential stress on the sample. Consistent results using multiple pressure standards were obtained. By fitting the pressure-volume data to a Birch-Murnaghan equation of state, the isothermal bulk modulus and its corresponding pressure derivative at zero pressure were determined to be K0=70.1±0.7 GPa, and K‧0=4.3±0.1. If the bulk modulus is fixed at 66.2 GPa, a value well constrained by independent elasticity measurements, we obtain K‧0=4.6±0.1. The bulk modulus and its pressure derivative obtained from this work resolve the large discrepancy in previously reported values of K0 and K‧0 for this material. Consequently, the equation of state of LiF is now sufficiently well constrained to allow its use as a pressure calibrant in high pressure experiments.

  14. Surface crystallization of a fluoride glass

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Doremus, Robert H.

    1983-01-01

    Growth of crystals on the surface of a Zr-Ba-La fluoride glass was observed by optical and scanning electron microscopy. Small, dark crystal nucleated rapidly and grew to a size of about 10 microns; then they stopped growing, and wrinkled regions emerged, covering the entire crystal surface.

  15. Anodic oxidation of sulfide ions in molten lithium fluoride

    SciTech Connect

    Lloyd, C.L.; Gilbert, J.B. II . Applied Research Lab.)

    1994-10-01

    The study of sulfur and sulfide oxidation in molten salt systems is of current interest in high energy battery, and metallurgical applications. Cyclic voltammetry experiments have been performed on lithium sulfide in a lithium fluoride electrolyte at 1,161 K using a graphite working electrode and a platinum quasi-reference electrode. Two distinct oxidation mechanisms are observed for the sulfide ions. The first oxidation produces sulfur and at a higher potential a disulfide species is proposed to have formed. Both oxidations appear to be reversible and diffusion controlled.

  16. Crystallization of lithium borate glasses

    NASA Technical Reports Server (NTRS)

    Goktas, A. A.; Neilson, G. F.; Weinberg, M. C.

    1992-01-01

    The glass-forming ability and crystallization behavior of lithium borate compositions, in the diborate-to-metaborate-range, were studied. In particular, the nature and sequence of formation of crystalline phases and the tendency toward devitrification were investigated as functions of temperature, thermal history and batch composition. It was found that the sequence of crystalline phase formation was sensitive to all of the three latter factors, and it was observed that under certain conditions metastable defect structures of the metaborate can appear.

  17. Optical Restoration of Lead Fluoride Crystals

    SciTech Connect

    Spilker, A.; Cole, P. L.; Forest, T. A.; Mestari, M.; Naeem, S.; LeBaron, N.; Bertin, P.; Camacho, C. Munoz; Roche, J.

    2009-03-10

    Due to its relatively high resistance to high radiation, lead fluoride (PbF{sub 2}) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF{sub 2} crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF{sub 2} samples with 1.1 and 1.3 MeV gammas from {sup 60}Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410-450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF{sub 2} samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching.

  18. Effects of Systemic Fluoride and in vitro Fluoride Treatment on Enamel Crystals

    PubMed Central

    Chen, H.; Czajka-Jakubowska, A.; Spencer, N.J.; Mansfield, J.F.; Robinson, C.; Clarkson, B.H.

    2008-01-01

    Systemically administered fluoride at a concentration of 75 ppm increases the surface roughness of developing enamel crystals in rats, which may be significant in advancing our understanding of the biological mechanism of fluorosis. Thus, the aim of this study was to investigate whether the increased surface roughness may be a result of surface restructuring by the direct action of fluoride at the crystal surface. We examined the fluoride dose-dependent roughening of enamel crystal surfaces in vivo, in the rat, and whether this roughening could be mimicked by the in vitro treatment of rat enamel crystals with neutral pH fluoride solutions. Our results showed that enamel crystal surface roughness increased after treatment with increasing fluoride ion concentrations, whether applied in vitro or administered systemically. This suggests a mechanism, alongside others, for the increased surface roughness of crystals in fluorotic enamel. PMID:17062747

  19. Formation of lithium fluoride/metal nanocomposites for energy storage through solid state reduction of metal fluorides

    SciTech Connect

    Amatucci, GG; Pereira, N; Badway, F; Sina, M; Cosandey, F; Ruotolo, M; Cao, C

    2011-12-01

    In order to utilize high energy metal fluoride electrode materials as direct replacement electrode materials for lithium ion batteries in the future, a methodology to prelithiate the cathode or anode must be developed. Herein, we introduce the use of a solid state Li(3)N route to achieve the lithiation and mechanoreduction of metal fluoride based nanocomposites. The resulting prelithiation was found to be effective with the formation of xLiF:Me structures of very fine nanodimensions analogous to what is found by electrochemical lithiation. Physical and electrochemical properties of these nanocomposites for the bismuth and iron lithium fluoride systems are reported. (C) 2011 Elsevier B.V. All rights reserved.

  20. Crystallization of heavy metal fluoride glasses

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Bruce, Allan J.; Doremus, R. H.; Moynihan, C. T.

    1984-01-01

    The kinetics of crystallization of a number of fluorozirconate glasses were studied using isothermal and dynamic differential scanning calorimetry and X-ray diffraction. The addition of the fluorides LiF, NaF, AlF3, LaF3 to a base glass composition of ZrF4-BaF2 reduced the tendency to crystallize, probably by modifying the viscosity-temperature relation. ZrF4-BaF2-LaF3-AlF3-NaF glass was the most stable against devitrification and perhaps is the best composition for optical fibers with low scattering loss. Some glasses first crystallize out into metastable beta-BaZr2F10 and beta-BaZrF6 phases, which transform into the most stable alpha-phases when heated to higher temperatures. The size of the crystallites was estimated to be about 600 A from X-ray diffraction.

  1. Zirconium fluoride glass - Surface crystals formed by reaction with water

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

    1984-01-01

    The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

  2. Radiation and phase change of lithium fluoride in an annulus

    NASA Technical Reports Server (NTRS)

    Lund, Kurt O.

    1993-01-01

    A one-dimensional thermal model is developed to evaluate the effect of radiation on the phase change of lithium-fluoride (LiF) in an annular canister under gravitational and microgravitational conditions. Specified heat flux at the outer wall of the canister models focused solar flux; adiabatic and convective conditions are considered for the inner wall. A two-band radiation model is used for the combined-mode heat transfer within the canister, and LiF optical properties relate metal surface properties in vacuum to those in LiF. For axial gravitational conditions, the liquid LiF remains in contact with the two bounding walls, whereas a void gap is used at the outer wall to model possible microgravitational conditions. For the adiabatic cases, exact integrals are obtained for the time required for complete melting of the LiF. Melting was found to occur primarily from the outer wall in the 1-g model, whereas it occurred primarily from the inner wall in the mu-g model. For the convective cases, partially melted steady-state conditions and fully melted conditions are determined to depend on the source flux level, with radiation extending the melting times.

  3. Vapor liquid equilibria on the ternary lithium fluoride-sodium fluoride-beryllium fluoride system

    NASA Astrophysics Data System (ADS)

    Fukuda, Grant Takeshi

    Molten mixtures of LiF, NaF, and BeF2 (FLiNaBe) have been proposed as a liquid first wall for selected fusion reactor designs. Because currently envisaged reactor technologies for igniting and/or sustaining a, fusion reaction require vacuum conditions, the volatility of these liquids is an issue for concern. Many physical properties of the ternary LiF-NaF-BeF 2 (FLiNaBe) system have already been studied as part of the molten salt reactor program, but the vapor pressure has not been measured. A study of the vapor liquid equilibrium of FLiNaBe by Thermogravimetric Analysis (TGA) and Knudsen Cell Mass Spectrometry (KCMS) is presented. The ternary system is treated as a pseudo-binary system by fixing the ratio of LiF:NaF and varying the amount of BeF2. Measurements have been performed over a composition range of 0.3--0.8 mole fraction BeF2 and from 875--975K. Experimental data, are correlated in terms of the BeF 2 activity coefficient. Measurements were also carried out on the binary systems LiF-BeF2 and NaF-BeF2. Measured values of the BeF2 activity coefficient in the binary LiF-BeF2 and NaF-BeF2 systems compare satisfactorily with previous results published in the research literature. The vapor phase of FLiNaBe was found to consist of primarily the species BeF2, LiBeF3, and NaBeF 3 over the temperature and composition range studied. Mixtures of BeF2-containing fluoride salts are highly non-ideal; the BeF2 activity coefficient exhibits both positive and negative deviations from ideality over the composition range studied. An associated solution model with 3 adjustable parameters is used to fit the BeF2 activity coefficient data of the LiF-BeF2 and NaF-BeF2 systems. The parameters obtained from fitting binary data are then used to fit the ternary system. The extension of the model to the ternary system results in a single additional parameter that can only be determined from fitting ternary data. Overall the agreement between the model and experimental data is within

  4. Hot filament technique for measuring the thermal conductivity of molten lithium fluoride

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Perry, William D.

    1990-01-01

    Molten salts, such as lithium fluoride, are attractive candidates for thermal energy storage in solar dynamic space power systems because of their high latent heat of fusion. However, these same salts have poor thermal conductivities which inhibit the transfer of heat into the solid phase and out of the liquid phase. One concept for improving the thermal conductivity of the thermal energy storage system is to add a conductive filler material to the molten salt. High thermal conductivity pitch-based graphite fibers are being considered for this application. Although there is some information available on the thermal conductivity of lithium fluoride solid, there is very little information on lithium fluoride liquid, and no information on molten salt graphite fiber composites. This paper describes a hot filament technique for determining the thermal conductivity of molten salts. The hot filament technique was used to find the thermal conductivity of molten lithium fluoride at 930 C, and the thermal conductivity values ranged from 1.2 to 1.6 W/mK. These values are comparable to the slightly larger value of 5.0 W/mK for lithium fluoride solid. In addition, two molten salt graphite fiber composites were characterized with the hot filament technique and these results are also presented.

  5. Crystallization, Optical and Chemical Properties of Fluoride Glasses

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1985-01-01

    Fluoride glasses have great promise as infrared optical components, especially fibers, because they are transparent to 8 micrometers and higher. In order to optimize properties, different glass compositions are needed. Some are hard to form in a container, and may possibly be formable in a containerless furnace. Understanding of crystallization with and without a container could lead to glasses with optimum properties. Chemical durability (attack by water) can limit or extend the applicability of fluoride glasses. Progress to date is given.

  6. Nuclear quantum effects in water exchange around lithium and fluoride ions

    SciTech Connect

    Wilkins, David M.; Manolopoulos, David E.; Dang, Liem X.

    2015-02-14

    We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the exchange processes are unaffected by quantization, so a classical description of these reactions gives qualitatively correct and quantitatively reasonable results. We also find that the quantum effects in solutions of lithium are larger than in solutions of fluoride. This is partly due to the stronger interaction of lithium with water molecules, partly due to the lighter mass of lithium and partly due to competing quantum effects in the hydration of fluoride, which are absent in the hydration of lithium.

  7. Nuclear quantum effects in water exchange around lithium and fluoride ions

    SciTech Connect

    Wilkins, David M.; Manolopoulos, David; Dang, Liem X.

    2015-02-14

    We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the water exchange reactions are unaffected by quantization, so a classical description of these reactions gives qualitatively correct and quantitatively reasonable results. We also find that the quantum effects in solutions of lithium are larger than in solutions of fluoride. This is partly due to the stronger interaction of lithium with water molecules, partly due to the lighter mass of lithium, and partly due to competing quantum effects in the hydration of fluoride, which are absent in the hydration of lithium. LXD was supported by US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.

  8. Nuclear quantum effects in water exchange around lithium and fluoride ions.

    PubMed

    Wilkins, David M; Manolopoulos, David E; Dang, Liem X

    2015-02-14

    We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the exchange processes are unaffected by quantization, so a classical description of these reactions gives qualitatively correct and quantitatively reasonable results. We also find that the quantum effects in solutions of lithium are larger than in solutions of fluoride. This is partly due to the stronger interaction of lithium with water molecules, partly due to the lighter mass of lithium and partly due to competing quantum effects in the hydration of fluoride, which are absent in the hydration of lithium.

  9. Observations of the freeze/thaw performance of lithium fluoride by motion picture photography

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Perry, W. D.

    1991-01-01

    To gain direct observation of the molten salt phase change, a novel containerless technique was developed where the high surface tension of lithium fluoride was used to suspend a bead of the molten salt inside a specially designed wire cage. By varying the current passing through the wire, the cage also served as a variable heat source. In this way, the freeze/thaw performance of the lithium fluoride could be photographed by motion picture photography without the influence of container walls. The motion picture photography of the lithium fluoride sample revealed several zones during the phase change, a solid zone and a liquid zone, as expected, and a slush zone that was predicted by thermal analysis modeling.

  10. Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture

    NASA Technical Reports Server (NTRS)

    Yue, A. S.; Yeh, C. W.; Yue, B. K.

    1982-01-01

    Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

  11. Effects of light exposure on irradiated barium fluoride crystals

    SciTech Connect

    Wuest, C.R.; Mauger, G.J.

    1993-04-20

    Small barium fluoride crystals have been irradiated using cobalt-60 gamma rays under various illumination conditions to establish the effect of photo-bleaching of the radiation-induced color centers. This paper describes results of a few different experiments conducted at LLNL over the past few weeks.

  12. Surface tension of molten mixtures of fluorides of lithium, beryllium, and thorium

    SciTech Connect

    Klimenkov, A.A.; Chevinskii, Y.F.; Kurbatov, N.N.; Raspopin, S.P.

    1984-12-01

    Melts of mixtures of fluorides of lithium, beryllium, thorium and uranium satisfy most completely the many requirements imposed on fuel composites and breeder-zone materials in a liquid-salt nuclear reactor, and therefore there is a need for information on the physicochemical properties of such melts. This paper reports on a study in which the surface tension of three-component melts containing fluorides of thorium, beryllium and lithium were measured by the maximum-pressure method in a gas bubble. The salts investigated were placed in glass carbon crucibles. The material used for the capillaries was nickel, which is resistant to the action of fluoride melts. As the working gas, the authors used argon from which the traces of moisture and oxygen had been removed. The surface tension was calculated by the Cantor-Schrodinger method and in the investigations close attention was paid to the preparation of the appropriate anhydrous salts.

  13. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

    1997-10-14

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

  14. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, Kathleen I.; DeLoach, Laura D.; Payne, Stephen A.; Keszler, Douglas A.

    1997-01-01

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

  15. Electron emission from polycrystalline lithium fluoride bombarded by slow multicharged ions

    NASA Astrophysics Data System (ADS)

    Vana, M.; Aumayr, F.; Varga, P.; Winter, H. P.

    1995-06-01

    Total electron yields have been determined from electron emission statistics measured for impact of H +, N q+ ( q = 1, 5, 6) and Ar q+ ( q = 1, 3, 6, 9) on clean, polycrystalline lithium fluoride. Ion impact energies have been varied from almost zero up to 10 × q keV. The obtained total electron yields deviate considerably from available data derived via ion- and electron current measurements for LiF single crystal targets. Our results are explained by comparison with a recent model for MCI induced potential electron emission from clean metal surfaces, which has been properly adapted, available theory for kinetic electron emission from alkalihalide surfaces, and by considering also measured secondary electron yields for LiF. Dependences of the electron emission statistics and -yields on projectile impact energy and -charge differ strongly from corresponding properties for clean metal surfaces, which can be explained from the different roles of potential- and kinetic emission and, in particular, a relatively stronger contribution from secondary electron emission induced by fast electrons from finally neutralising projectiles inside the LiF bulk.

  16. Quantum monte carlo study of the energetics of small hydrogenated and fluoride lithium clusters.

    PubMed

    Moreira, N L; Brito, B G A; Rabelo, J N Teixeira; Cândido, Ladir

    2016-06-30

    An investigation of the energetics of small lithium clusters doped either with a hydrogen or with a fluorine atom as a function of the number of lithium atoms using fixed-node diffusion quantum Monte Carlo (DMC) simulation is reported. It is found that the binding energy (BE) for the doped clusters increases in absolute values leading to a more stable system than for the pure ones in excellent agreement with available experimental measurements. The BE increases for pure, remains almost constant for hydrogenated, and decreases rapidly toward the bulk lithium for the fluoride as a function of the number of lithium atoms in the clusters. The BE, dissociation energy as well as the second difference in energy display a pronounced odd-even oscillation with the number of lithium atoms. The electron correlation inverts the odd-even oscillation pattern for the doped in comparison with the pure clusters and has an impact of 29%-83% to the BE being higher in the pure cluster followed by the hydrogenated and then by the fluoride. The dissociation energy and the second difference in energy indicate that the doped cluster Li3 H is the most stable whereas among the pure ones the more stable are Li2 , Li4 , and Li6 . The electron correlation energy is crucial for the stabilization of Li3 H. © 2016 Wiley Periodicals, Inc. PMID:26992447

  17. Spectroscopic Investigation of Ce(3+) Doped Fluoride Crystals

    NASA Technical Reports Server (NTRS)

    Reinhart, Donald H.; Armagan, Guzin; Marsh, Waverly; Barnes, James; Chai, B. H. T.

    1995-01-01

    Doping of the trivalent rare-earth cerium ion into fluoride crystals is of interest in producing turnable ultra-violet solid state lasers. These lasers are desirable for many applications in medicine, industry, and scientific research, including remote sensing. High absorption and stimulated emission cross sections of the dipole allowed 4f-5d transitions show promise in cerium as a laser ion in crystals. Several research groups have already reported the observation of stimulated emission of cerium in LiYF4, LiSrAlF6, and LiCaAlF6. However, the color center formation in the crystals due to the excited state absorption of ultra-violet pump light adds difficulty to achieving laser action. We have investigated the spectroscopic properties of cerium such as absorption and emission spectra, and lifetimes in four different fluoride crystals, including LiCaAlF6, LiSrAlF6, KyF4 and LiYF4. We have derived the polarized absorption and stimulated emission cross sections from transmission and fluorescence emission measurements for each of the host crystals. we have measured the lifetime of the lowest 5d level; moreover, investigated the temperature dependence of this lifetime and color center formation. Our results on absorption and stimulated emission cross sections for LiCaAlF6 and LiSrAlF6 are similar to the results already published.

  18. Magnesium oxide doping reduces acoustic wave attenuation in lithium metatantalate and lithium metaniobate crystals

    NASA Technical Reports Server (NTRS)

    Croft, W.; Damon, R.; Kedzie, R.; Kestigian, M.; Smith, A.; Worley, J.

    1970-01-01

    Single crystals of lithium metatantalate and lithium metaniobate, grown from melts having different stoichiometries and different amounts of magnesium oxide, show that doping lowers temperature-independent portion of attenuation of acoustic waves. Doped crystals possess optical properties well suited for electro-optical and photoelastic applications.

  19. Shrinkage void formation and its effect on freeze and thaw processes of lithium and lithium-fluoride for space applications

    NASA Technical Reports Server (NTRS)

    Yang, Jae Y.; El-Genk, Mohamed S.

    1991-01-01

    The effects of shrinkage void forming during freezing of lithium and lithium fluoride on subsequent thaw processes are investigated using a numerical scheme that is based on a single (solid/liquid) cell approach. Results show that a void forming at the wall appreciably reduces the solid-liquid interface velocity, during both freeze and thaw, and causes a substantial rise in the wall temperature during thaw. However, in the case of Li, the maximum wall temperature was much lower than the melting temperature of PWC-11, which is used as the structure material in the SP-100 system. Hence, it is concluded that a formation of hot spots is unlikely during the startup or restart of the SP-100 system.

  20. An investigation of voids formation mechanisms and their effects on freeze and thaw processes of lithium and lithium fluoride

    NASA Technical Reports Server (NTRS)

    El-Genk, Mohamed S.; Yang, Jae-Young

    1991-01-01

    The mechanisms of void formation during the cooldown and freezing of lithium coolant within the primary loop of SP-100 type systems are investigated. These mechanisms are: (1) homogeneous nucleation; (2) heterogeneous nucleation; (3) normal segregation of helium gas dissolved in liquid lithium; and (4) shrinkage of lithium during freezing. To evaluate the void formation potential due to segregation, a numerical scheme that couples the freezing and mass diffusion processes in both the solid and liquid regions is developed. The results indicated that the formation of He bubbles is unlikely by either homogeneous or heterogeneous nucleation during the cooldown process. However, homogeneous nucleation of He bubbles following the segregation of dissolved He in liquid lithium ahead of the solid-liquid interface is likely to occur. Results also show that total volume of He void is insignificant when compared to that of shrinkage voids. In viewing this, the subsequent research focuses on the effects of shrinkage void forming during freezing of lithium on subsequent thaw processes are investigated using a numerical scheme that is based on a single (solid/liquid) cell approach. The cases of lithium-fluoride are also investigated to show the effect of larger volume shrinkage upon freezing on the freeze and thaw processes. Results show that a void forming at the wall appreciably reduces the solid-liquid interface velocity, during both freeze and thaw, and causes a substantial rise in the wall temperature during thaw. However, in the case of Li, the maximum wall temperature was much lower than the melting temperature of PWC-11, which is used as the structure material in the SP-100 system. Hence, it is included that a formation of hot spots is unlikely during the startup or restart of the SP-100 system.

  1. Carbon Nanohorns Carried Iron Fluoride Nanocomposite with ultrahigh rate lithium ion storage properties

    PubMed Central

    Fan, Lishuang; Li, Bingjiang; Zhang, Naiqing; Sun, Kening

    2015-01-01

    Novel hierarchical carbon nanohorns (CNHs) carried iron fluoride nanocomposites have been constructed by direct growth of FeF3·0.33H2O nanoparticles on CNHs. In the FeF3·0.33H2O@CNHs nanocomposite, the mesopore CNHs play the role as conductive matrix and robust carrier to support the FeF3·0.33H2O nanoparticles. The intimate conductive contact between the two components can build up an express way of electron transfer for rapid Li+ insertion/extraction. The CNHs can not only suppress the growth and agglomeration of FeF3·0.33H2O during the crystallization process, but also sever as an “elastic confinement” to support FeF3·0.33H2O. As was to be expected, the hierarchical FeF3·0.33H2O@CNHs nanocomposite exhibits impressive rate capability and excellent cycle performance. Markedly, the nanocomposite proves stable, ultrahigh rate lithium ion storage properties of 81 mAh g−1 at charge/discharge rate of 50 C (a discharge/charge process only takes 72 s). The integration of high electron conductivity, confined nano sized FeF3·0.33H2O (~5 nm), hierarchical mesopores CNHs and the “elastic confinement” support, the FeF3·0.33H2O@CNHs nanocomposite demonstrates excellent ultrahigh rate capability and good cycling properties. PMID:26173994

  2. Viscosity of molten lithium, thorium and beryllium fluorides mixtures

    NASA Astrophysics Data System (ADS)

    Merzlyakov, Alexander V.; Ignatiev, Victor V.; Abalin, Sergei S.

    2011-12-01

    Considering development of Molten Salt Fast Reactor (MSFR) concept, following Molten Salt fluorides mixtures have been chosen as an object for viscosity studies in this work (in mol%): 78LiF-22ThF 4; 71LiF-27ThF 4-2BeF 2 and 75LiF-20ThF 4-5BeF 2. Additionally, the effect of the 3 mol% CeF 3 additives on viscosity of the molten 75LiF-20ThF 4-5BeF 2 (mol%) salt mixture has been investigated experimentally. The method of torsional oscillations of cylindrical crucible filled by molten fluorides mixture has been chosen for kinematic viscosity measurement at temperatures up to 800-850 °C. In temperature ranges, where melts behave as normal liquids, dependences on viscosity vs. temperature are received: ν = А exp [B/T(K)], where ν - kinematic viscosity, m 2/s; T - temperature, K. The kinematic viscosity Rout mean squares (RMS) estimated in the assumption about dispersion homoscedasticity is (0.04-0.12) × 10 -6 (m 2/s). Discrepancies left in the data of viscosity for molten mixtures of LiF, BeF 2 and ThF 4 received by different researchers need further investigations in this area to be continued.

  3. Crystal structure of advanced lithium titanate with lithium oxide additives

    NASA Astrophysics Data System (ADS)

    Hoshino, Tsuyoshi; Sasaki, Kazuya; Tsuchiya, Kunihiko; Hayashi, Kimio; Suzuki, Akihiro; Hashimoto, Takuya; Terai, Takayuki

    2009-04-01

    Li 2TiO 3 is one of the most promising candidates among solid breeder materials proposed for fusion reactors. However, the mass of Li 2TiO 3 was found to decrease with time in the sweep gas mixed with hydrogen. This mass change indicates that the oxygen content of the sample decreased, suggesting the change from Ti 4+ to Ti 3+. In the present paper, the crystal structure and the non-stoichiometry of Li 2TiO 3 added with Li 2O have been extensively investigated by means of X-ray diffraction (XRD) and thermogravimetry. In the case of the Li 2TiO 3 samples used in the present study, LiO-C 2H 5 or LiO-i-C 3H 7 and Ti(O-i-C 3H 7) 4 were mixed in the proportion corresponding to the molar ratio Li 2O/TiO 2 of either 2.00 or 1.00. In thermogravimetry, the mass of this sample decreased with time due to lithium deficiency, where no presence of oxygen deficiency was indicated.

  4. Efficient holmium:yttrium lithium fluoride laser longitudinally pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1987-01-01

    Optical pumping of a holmium:yttrium lithium floride (Ho:YLF) crystal with a 790-nm continuous-wave diode-laser array has generated 56 mW of 2.1-micron laser radiation with an optical-to-optical conversion slope efficiency of 33 percent while the crystal temperature is held at 77 K. The lasing threshold occurs at 7 mW of input power, and laser operation continues up to a crystal temperature of 124 K.

  5. An experimental analysis of a doped lithium fluoride direct absorption solar receiver

    NASA Technical Reports Server (NTRS)

    Kesseli, James; Pollak, Tom; Lacy, Dovie

    1988-01-01

    An experimental analysis of two key elements of a direct absorption solar receiver for use with Brayton solar dynamic systems was conducted. Experimental data are presented on LiF crystals doped with dysprosium, samarium, and cobalt fluorides. In addition, a simulation of the cavity/window environment was performed and a posttest inspection was conducted to evaluate chemical reactivity, transmissivity, and condensation rate.

  6. Role of ammonium fluoride in crystallization process of beta zeolite

    NASA Astrophysics Data System (ADS)

    Jon, Hery; Oumi, Yasunori; Itabashi, Keiji; Sano, Tsuneji

    2007-09-01

    The addition of Na + cations to the starting gel prepared using NH 4F significantly prolonged the crystallization time of beta zeolite. However, in the case of pure silica beta zeolite an addition of more NH 4F reduced the crystallization time by one-half. From 29Si MAS NMR measurements, the signal attributed to pentacoordinated silicon was found to be more pronounced for pure silica beta zeolite in the presence of Na + cations even in the solid phase with low crystallinity, as compared to that in the absence of Na + cations. Considering the results of theoretical calculation, because of more energetically stable state of Na +[SiO 4/2F] - species, it could be presumed that Na +[SiO 4/2F] - species might exist in pure silica beta zeolite. Furthermore, as confirmed by 19F MAS NMR measurements tetraethylammonium fluoride (TEAF) species were enclathrated intact in solid phase during the initial crystallization stage. This suggests that TEAF species are required for the formation of beta zeolite framework, in other words, as "SDA" which conditions the formation of kinetically favored phase, i.e., beta zeolite. Moreover, since part of TEA + cations is replaced by sodium cations, forming Na +[SiO 4/2F] - species, the amount of TEA +[SiO 4/2F] - species involved in either nucleation or crystal growth decreases and thus the crystallization time becomes longer.

  7. Fluoride Inhibition of Enolase: Crystal Structure and Thermodynamics

    SciTech Connect

    Qin, Jie; Chai, Geqing; Brewer, John M.; Lovelace, Leslie L.; Lebioda, Lukasz

    2010-12-03

    Enolase is a dimeric metal-activated metalloenzyme which uses two magnesium ions per subunit: the strongly bound conformational ion and the catalytic ion that binds to the enzyme-substrate complex inducing catalysis. The crystal structure of the human neuronal enolase-Mg{sub 2}F{sub 2}P{sub i} complex (enolase fluoride/phosphate inhibitory complex, EFPIC) determined at 1.36 {angstrom} resolution shows that the combination of anions effectively mimics an intermediate state in catalysis. The phosphate ion binds in the same site as the phosphate group of the substrate/product, 2-phospho-d-glycerate/phosphoenolpyruvate, and induces binding of the catalytic Mg{sup 2+} ion. One fluoride ion bridges the structural and catalytic magnesium ions while the other interacts with the structural magnesium ion and the ammonio groups of Lys 342 and Lys 393. These fluoride ion positions correspond closely to the positions of the oxygen atoms of the substrate's carboxylate moiety. To relate structural changes resulting from fluoride, phosphate, and magnesium ions binding to those that are induced by phosphate and magnesium ions alone, we also determined the structure of the human neuronal enolase-Mg{sub 2}Pi complex (enolase phosphate inhibitory complex, EPIC) at 1.92 {angstrom} resolution. It shows the closed conformation in one subunit and a mixture of open and semiclosed conformations in the other. The EPFIC dimer is essentially symmetric while the EPIC dimer is asymmetric. Isothermal titration calorimetry data confirmed binding of four fluoride ions per dimer and yielded K{sub b} values of 7.5 x 10{sup 5} {+-} 1.3 x 10{sup 5}, 1.2 x 10{sup 5} {+-} 0.2 x 10{sup 5}, 8.6 x 10{sup 4} {+-} 1.6 x 10{sup 4}, and 1.6 x 10{sup 4} {+-} 0.7 x 10{sup 4} M{sup -1}. The different binding constants indicate negative cooperativity between the subunits; the asymmetry of EPIC supports such an interpretation.

  8. Fluoride

    MedlinePlus

    Fluoride is used to prevent tooth decay. It is taken up by teeth and helps to strengthen ... and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose ...

  9. Polyethylene-supported polyvinylidene fluoride-cellulose acetate butyrate blended polymer electrolyte for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Liu, Jiansheng; Li, Weishan; Zuo, Xiaoxi; Liu, Shengqi; Li, Zhao

    2013-03-01

    The polyethylene (PE)-supported polymer membranes based on the blended polyvinylidene fluoride (PVDF) and cellulose acetate butyrate (CAB) are prepared for gel polymer electrolyte (GPE) of lithium ion battery. The performances of the prepared membranes and the resulting GPEs are investigated by scanning electron microscopy, electrochemical impedance spectroscopy, linear potential sweep, and charge-discharge test. The effect of the ratio of PVDF to CAB on the performance of the prepared membranes is considered. It is found that the GPE based on the blended polymer with PVDF:CAB = 2:1 (in weight) has the largest ionic conductivity (2.48 × 10-3 S cm-1) and shows good compatibility with anode and cathode of lithium ion battery. The LiCoO2/graphite battery using this GPE exhibits superior cyclic stability at room temperature, storage performance at elevated temperature, and rate performance.

  10. Crystal chemistry of hydrothermally grown ternary alkali rare earth fluorides.

    PubMed

    McMillen, Colin D; Comer, Sara; Fulle, Kyle; Sanjeewa, Liurukara D; Kolis, Joseph W

    2015-12-01

    The structural variations of several alkali metal rare earth fluoride single crystals are summarized. Two different stoichiometric formulations are considered, namely those of ARE2F7 and ARE3F10 (A = K, Rb, Cs; RE = Y, La-Lu), over a wide range of ionic radii of both the alkali and rare earth (RE) ions. Previously reported and several new single-crystal structures are considered. The new single crystals are grown using hydrothermal methods and the structures are compared with literature reports of structures grown from both melts and hydrothermal fluids. The data reported here are combined with the literature data to gain a greater understanding of structural subtleties surrounding these systems. The work underscores the importance of the size of the cations to the observed structure type and also introduces synthetic technique as a contributor to the same. New insights based on single-crystal structure analysis in the work introduce a new disordered structure type in the case of ARE2F7, and examine the trends and boundaries of the ARE3F10 stoichiometry. Such fundamental structural information is useful in understanding the potential applications of these compounds as optical materials. PMID:26634734

  11. Crystal chemistry of hydrothermally grown ternary alkali rare earth fluorides.

    PubMed

    McMillen, Colin D; Comer, Sara; Fulle, Kyle; Sanjeewa, Liurukara D; Kolis, Joseph W

    2015-12-01

    The structural variations of several alkali metal rare earth fluoride single crystals are summarized. Two different stoichiometric formulations are considered, namely those of ARE2F7 and ARE3F10 (A = K, Rb, Cs; RE = Y, La-Lu), over a wide range of ionic radii of both the alkali and rare earth (RE) ions. Previously reported and several new single-crystal structures are considered. The new single crystals are grown using hydrothermal methods and the structures are compared with literature reports of structures grown from both melts and hydrothermal fluids. The data reported here are combined with the literature data to gain a greater understanding of structural subtleties surrounding these systems. The work underscores the importance of the size of the cations to the observed structure type and also introduces synthetic technique as a contributor to the same. New insights based on single-crystal structure analysis in the work introduce a new disordered structure type in the case of ARE2F7, and examine the trends and boundaries of the ARE3F10 stoichiometry. Such fundamental structural information is useful in understanding the potential applications of these compounds as optical materials.

  12. Measurement of the Melting Point Temperature of Several Lithium-Sodium-Beryllium Fluoride Salt (Flinabe) Mixtures

    SciTech Connect

    McDonald, J.M; Nygren, R.E.; Lutz, T.J.; Tanaka, T.J; Ulrickson, M.A.; Boyle, T.J.; Troncosa, K.P.

    2005-04-15

    The molten salt Flibe, a combination of lithium and beryllium fluorides studied for molten salt fission reactors, has been proposed as a breeder and coolant for fusion applications. The melting points of 2LiF-BeF{sub 2} and LiF-BeF{sub 2} are 460 deg. C and 363 deg. C, but LiF-BeF{sub 2} is rather viscous and has less lithium for breeding. In the Advanced Power Extraction (APEX) Program, concepts with a free flowing liquid for the first wall and blanket were investigated. Flinabe (a mixture of LiF, BeF{sub 2} and NaF) was selected for a molten salt design because a melting temperature below 350 deg. C appeared possible and this provided an attractive operating temperature window for a reactor. To confirm that a ternary salt with a low melting temperature existed, several combinations of the fluoride salts, LiF, NaF and BeF{sub 2}, were melted in a stainless steel crucible under vacuum. One had an apparent melting temperature of 305 deg. C. The test system, preparation of the mixtures, melting procedures and temperature curves for the melting and cooling are presented along with the apparent melting points. Thermal modeling of the salt pool and crucible is reported in an accompanying paper.

  13. Broadband X-ray edge-enhancement imaging of a boron fibre on lithium fluoride thin film detector

    NASA Astrophysics Data System (ADS)

    Nichelatti, E.; Bonfigli, F.; Vincenti, M. A.; Cecilia, A.; Vagovič, P.; Baumbach, T.; Montereali, R. M.

    2016-10-01

    The white beam (∼6-80 keV) available at the TopoTomo X-ray beamline of the ANKA synchrotron facility (KIT, Karlsruhe, Germany) was used to perform edge-enhancement imaging tests on lithium fluoride radiation detectors. The diffracted X-ray image of a microscopic boron fibre, consisting of tungsten wire wrapped by boron cladding, was projected onto lithium fluoride thin films placed at several distances, from contact to 1 m . X-ray photons cause the local formation of primary and aggregate colour centres in lithium fluoride; these latter, once illuminated under blue light, luminesce forming visible-light patterns-acquired by a confocal laser scanning microscope-that reproduce the intensity of the X-ray diffracted images. The tests demonstrated the excellent performances of lithium fluoride films as radiation detectors at the investigated photon energies. The experimental results are here discussed and compared with those calculated with a model that takes into account all the processes that concern image formation, storing and readout.

  14. Birefringence simulation of annealed ingot of calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Ogino, H.; Miyazaki, N.; Mabuchi, T.; Nawata, T.

    2008-01-01

    We developed a method for simulating birefringence of an annealed ingot of calcium fluoride single crystal caused by the residual stress after annealing process. The method comprises the heat conduction analysis that provides the temperature distribution during the ingot annealing, the elastic thermal stress analysis using the assumption of the stress-free temperature that provides the residual stress after annealing, and the birefringence analysis of an annealed ingot induced by the residual stress. The finite element method was applied to the heat conduction analysis and the elastic thermal stress analysis. In these analyses, the temperature dependence of material properties and the crystal anisotropy were taken into account. In the birefringence analysis, the photoelastic effect gives the change of refractive indices, from which the optical path difference in the annealed ingot is calculated by the Jones calculus. The relation between the Jones calculus and the approximate method using the stress components averaged along the optical path is discussed theoretically. It is found that the result of the approximate method agrees very well with that of the Jones calculus in birefringence analysis. The distribution pattern of the optical path difference in the annealed ingot obtained from the present birefringence calculation methods agrees reasonably well with that of the experiment. The calculated values also agree reasonably well with those of the experiment, when a stress-free temperature is adequately selected.

  15. Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes

    SciTech Connect

    Wang, Feng; Robert, Rosa; Chernova, Natasha A.; Pereira, Nathalie; Omenya, Fredrick; Badway, Fadwa; Hua, Xiao; Ruotolo, Michael; Zhang, Ruigang; Wu, Lijun; Volkov, Vyacheslav; Su, Dong; Key, Baris; Whittingham, M. Stanley; Grey, Clare P.; Amatucci, Glenn G.; Zhu, Yimei; Graetz, Jason

    2015-10-15

    Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast

  16. Effect of Copper Oxide, Titanium Dioxide, and Lithium Fluoride on the Thermal Behavior and Decomposition Kinetics of Ammonium Nitrate

    NASA Astrophysics Data System (ADS)

    Vargeese, Anuj A.; Mija, S. J.; Muralidharan, Krishnamurthi

    2014-07-01

    Ammonium nitrate (AN) is crystallized along with copper oxide, titanium dioxide, and lithium fluoride. Thermal kinetic constants for the decomposition reaction of the samples were calculated by model-free (Friedman's differential and Vyzovkins nonlinear integral) and model-fitting (Coats-Redfern) methods. To determine the decomposition mechanisms, 12 solid-state mechanisms were tested using the Coats-Redfern method. The results of the Coats-Redfern method show that the decomposition mechanism for all samples is the contracting cylinder mechanism. The phase behavior of the obtained samples was evaluated by differential scanning calorimetry (DSC), and structural properties were determined by X-ray powder diffraction (XRPD). The results indicate that copper oxide modifies the phase transition behavior and can catalyze AN decomposition, whereas LiF inhibits AN decomposition, and TiO2 shows no influence on the rate of decomposition. Possible explanations for these results are discussed. Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Energetic Materials to view the free supplemental file.

  17. New UV instrumentation enabled by enhanced broadband reflectivity lithium fluoride coatings

    NASA Astrophysics Data System (ADS)

    Fleming, Brian T.; Quijada, Manuel A.; France, Kevin; Hoadley, Keri; Del Hoyo, Javier; Kruczek, Nicholas

    2015-08-01

    We present the results of a preliminary aging study of new enhanced broadband reflectivity lithium fluoride mirror coatings under development at the thin films laboratory at GSFC. These coatings have demonstrated greater than 80% reflectivity from the Lyman ultraviolet (~1020 Å) to the optical, and have the potential to revolutionize far-ultraviolet instrument design and capabilities. This work is part of a concept study in preparation for the fight qualification of these new coatings in a working astronomical environment. We outline the goals for TRL advancement, and discuss the instrument capabilities enabled by these high reflectivity broadband coatings on potential future space missions. We also present the early design of the first space experiment to utilize these coatings, the proposed University of Colorado sounding rocket payload SISTINE, and show how these new coatings make the science goals of SISTINE attainable on a suborbital platform.

  18. Surface-modified separators prepared with conductive polymer and aluminum fluoride for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Shin, Won-Kyung; Yoo, Ji-Hyun; Kim, Dong-Won

    2015-04-01

    Conventional polyethylene (PE) separators are surface-modified by thin coating with conductive poly(3,4-ethylenedioxythiophen)-co-poly(ethylene glycol) (PEDOT-co-PEG) copolymer and aluminum fluoride particles. The surface-modified separators exhibit a significant reduction in thermal shrinkage and an improved electrolyte uptake. By using these separators, the lithium-ion cells composed of carbon negative electrodes and LiNi1/3Co1/3Mn1/3O2 positive electrodes are assembled and their cycling performances are evaluated. The cells assembled with the surface-modified separators demonstrate superior cycling performance compared to cells prepared with pristine PE separator, both at ambient temperatures and at elevated temperature.

  19. Stoichiometry issues in single-crystal lithium tantalate

    NASA Astrophysics Data System (ADS)

    Bordui, P. F.; Norwood, R. G.; Bird, C. D.; Carella, J. T.

    1995-10-01

    Stoichiometry issues in lithium tantalate were studied through Czochralski growth of single crystals and vapor transport equilibration (VTE) of crystalline samples to specified Li/Ta compositions. Crystals were characterized through measurement of the ferroelectric Curie temperature Tc. The VTE experiments indicated a linear variation of Tc with Li/Ta ratio across the investigated range of 47.5-49.5 mol % Li2O. By control of initial melt stoichiometry, crystals representing melt fractions ≳90% were grown having compositional uniformity within ±0.015 mol % Li2O. Growth of the compositionally uniform crystals was determined to take place through incongruent solidification, with lithium rejection from the growth interface compensating for lithium volatilization from the melt surface. With the growth process applied, a melt composition of 48.39 mol % Li2O yielded grown crystals of a uniform 47.85 mol % Li2O solid composition. The lithium tantalate congruent composition was determined to lie at a value less than or equal to 47.70 mol % Li2O.

  20. Crystal structures of a double-barrelled fluoride ion channel

    PubMed Central

    Stockbridge, Randy B.; Kolmakova-Partensky, Ludmila; Shane, Tania; Koide, Akiko; Koide, Shohei; Miller, Christopher; Newstead, Simon

    2016-01-01

    To contend with hazards posed by environmental fluoride, microorganisms export this anion through F--specific ion channels of the Fluc family1–4. Since the recent discovery of Fluc channels, numerous idiosyncratic features of these proteins have been unearthed, including extreme selectivity for F- over Cl- and dual-topology dimeric assembly5–6. To understand the chemical basis for F- permeation and how the antiparallel subunits convene to form a F--selective pore, we solved crystal structures of two bacterial Fluc homologues in complex with three different monobody inhibitors, with and without F- present, to a maximum resolution of 2.1 Å. The structures reveal a surprising “double-barrelled” channel architecture in which two F- ion pathways span the membrane and the dual-topology arrangement includes a centrally coordinated cation, most likely Na+. F- selectivity is proposed to arise from the very narrow pores and an unusual anion coordination that exploits the quadrupolar edges of conserved phenylalanine rings. PMID:26344196

  1. New zirconium phosphate fluorides: Hydrothermal synthesis and crystal structures

    SciTech Connect

    Wloka, M.; Troyanov, S.I.; Kemnitz, E.

    1998-02-01

    A series of zirconium phosphate fluorides were synthesized and structurally characterized using different amines as templates. The compounds have the general formulas [amH{sub n}]{sub 1/n}[Zr{sub 2}(HPO{sub 4})(PO{sub 4}){sub 2}F]{center_dot}H{sub 2}O (1, am = ethylenediamine, n = 2; 2. am = N-methylethylenediamine, n = 2; 3, am = 1,3-diaminopropane, n = 2; 4, am = diethylenetriamine, n = 3) and [amH{sub 2}]{sub 0.5}[Zr{sub 2}(HPO{sub 4}){sub 2}(PO{sub 4})F{sub 2}]{center_dot}0.5H{sub 2}O (5, am = N,N,N{prime},N{prime}-tetramethylethylenediamine). In the structures of 2--4 with a Zr:F ratio of 2:1, there exists a three-dimensional arrangement of zirconium octahedra (one ZrO{sub 6} and one ZrO{sub 5}F) and phosphate tetrahedra (two PO{sub 4} and one HPO{sub 4}) connected via common oxygen atoms, whereas fluorine atoms and OH groups are terminal. These compounds crystallize in the ZrPO-1 structure type, which contains channels along the b axis formed by eight-membered rings of alternating PO{sub 4} tetrahedra and ZrO{sub 6} or ZrO{sub 5}F octahedra, respectively. The protonated disordered templates occupy the channels. Half the water molecules are situated in the positions alternatively left free by the disordered templates and the other half are bonded via hydrogen bridges to the terminal OH groups of the HPO{sub 4} tetrahedra. In contrast, the structure of 5 reveals a Zr:F ratio of 1:1, consequently forming a layer structure. The layers formed by ZrO{sub 5}F octahedra and PO{sub 4} or HPO{sub 4} tetrahedra, respectively, are linked by hydrogen bridges of type O{single_bond}H{hor_ellipsis}F and by weak H bonds over the protonated template. The similarities in connectivity pattern between Zr octahedra and P tetrahedra in all known zirconium phosphate fluorides and some zirconium phosphates are discussed.

  2. The influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate-pMMA composite cement.

    PubMed

    Oh, S H; Choi, S Y; Choi, S H; Lee, Y K; Kim, K N

    2004-01-01

    The objective of this study is to assess the influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate (CA)-polymethylmethacrylate (PMMA) composite cement exhibiting quick setting time ( < 15 min), low exothermic temperature (< 47 degrees C), and high compressive strength (> 100 MPa). The biocompatibility was measured by examining cytotoxicity tests such as the agar diffusion test with L929 cell line and the hemolysis test with fresh rabbit blood. To estimate the bioactivity of CA-PMMA composite cement, we determined hydroxyapatite (HAp) formation on the surface of composite cement in the simulated body (SBF) solution by using thin-film XRD, XPS, SEM, EPMA and ICP-AES. The results of biocompatibility tests indicated that all experimental compositions of this study had no cytotoxicity and no hemolysis so that there was no cytotoxicity with regard to non-reacted monomers (MMA and TEGDMA) and lithium fluoride. The results of bioactivity tests revealed that CA-PMMA composite cement without lithium fluoride did not form HAp on its surface after 60 days of soaking in the SBF. On the other hand, LiAl2(OH)7 . 2H2O and HAp were formed on the surface of CA-PMMA composite cement including 1.0% by weight of lithium fluoride after 7 and 15 days of soaking in the SBF, respectively. The 5 microm of LiAl2(OH)7 . 2H2O and HAp mixed layers were formed on the surface of specimen after 60 days of soaking in the SBF.

  3. A theoretical study of fluorides scintillating crystals: Methodology and application

    NASA Astrophysics Data System (ADS)

    Jiang, Huitian

    Theoretical computation and simulation study has been performed on important scintillating fluorides crystal BaF2 and PbF2. The structural, electronic, transport and defects properties are investigated under different methodology schemes. The thesis provide accurate and detailed understandings of fundamental electronic structures of them in different phases for the very first time. A new expanded module for which provide the CRYSTAL program package with full capability in ECP (effective pseudo-potential) method calculation is developed and successfully applied into the this study. We present the results of an all-electron first principles study on BaF 2 in its stable (cubic) and high-pressure phases. A LCAO (linear combination of atomic orbitals) approach in the framework of DFT is employed for total energy calculations in cubic, orthorhombic and hexagonal phases of BaF 2. A fitting of the energy surface to the equation of state yields the lattice constant and the bulk modulus of these phases at zero pressure which are in good agreement with the corresponding experimental values. Analysis of band structure determines the high-pressure phases to be direct-gap materials and no metallization of BaF2 is predicted to occur for pressures up to 50 GPa. Furthermore, several peaks observed in the spectroscopic experiments have been identified with interband transitions in the cubic BaF2. We also performed the small-core ECP first principles calculation on Pb2 in its cubic, orthorhombic and hexagonal phases. For cubic phase, the accurate theoretical band data now are available with the structural properties were very well generated. It is predicted with direct band gap at X. The band structures of orthorhombic and hexagonal phases are first time calculated. We predict the orthorhombic and hexagonal phase PbF2 has indirect band gap. These results may help to clarify some doubts and controversies in the experiments and promote the application studies. At last, a discussion on

  4. Precise, reproducible nano-domain engineering in lithium niobate crystals

    SciTech Connect

    Boes, Andreas Sivan, Vijay; Ren, Guanghui; Yudistira, Didit; Mitchell, Arnan; Mailis, Sakellaris; Soergel, Elisabeth

    2015-07-13

    We present a technique for domain engineering the surface of lithium niobate crystals with features as small as 100 nm. A film of chromium (Cr) is deposited on the lithium niobate surface and patterned using electron beam lithography and lift-off and then irradiated with a wide diameter beam of intense visible laser light. The regions patterned with chromium are domain inverted while the uncoated regions are not affected by the irradiation. With the ability to realize nanoscale surface domains, this technique could offer an avenue for fabrication of nano-photonic and phononic devices.

  5. Precise, reproducible nano-domain engineering in lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Boes, Andreas; Sivan, Vijay; Ren, Guanghui; Yudistira, Didit; Mailis, Sakellaris; Soergel, Elisabeth; Mitchell, Arnan

    2015-07-01

    We present a technique for domain engineering the surface of lithium niobate crystals with features as small as 100 nm. A film of chromium (Cr) is deposited on the lithium niobate surface and patterned using electron beam lithography and lift-off and then irradiated with a wide diameter beam of intense visible laser light. The regions patterned with chromium are domain inverted while the uncoated regions are not affected by the irradiation. With the ability to realize nanoscale surface domains, this technique could offer an avenue for fabrication of nano-photonic and phononic devices.

  6. In situ AFM crystal growth and dissolution study of calcite in the presence of aqueous fluoride

    NASA Astrophysics Data System (ADS)

    Vavouraki, A.; Putnis, C. V.; Putnis, A.; Koutsoukos, P. G.

    2009-04-01

    Fluoride is naturally abundant, encountered in rocks, soil and fresh and ocean water. Calcite crystals, during crystal growth may incorporate fluoride ions into their lattice (Okumura et al., 1983). In situ atomic force microscopy (AFM) has been used to study the growth and dissolution of calcite {104} surfaces in aqueous solutions in the presence of fluoride, using a fluid cell in which the supersaturated and the understaturated solutions respectively, flow over a freshly cleaved calcite crystal. For growth experiments, supersaturation index (S.I.) with respect to calcite was equal to 0.89 and the initial solution pH 10.2. The crystal growth rates were measured from the closure of the rhombohedral etch pits along the [010] direction induced by an initial dissolution step using pure water. The spreading rate of 2-dimensional nuclei was also measured along the same direction. In the presence of low fluoride concentrations (≤0.33 mM), the crystal growth rate of calcite was unaffected. At higher concentrations (up to 5 mM) growth rate decreased substantially to 50% of the rate in the absence of fluoride. Potential fluoride sorption over the calcite surface may ascribe the decrease of growth rates. Dissolution experiments were conducted at pH= 7.2 and dissolution rates of calcite were measured from the spreading of rhombohedral etch pits along both [010] and [42] directions. The presence of low concentrations of fluoride (≤1.1 mM) in the undersaturated solutions enhanced the dissolution rate along the [42] direction by 50% in comparison with pure water. The morphology of rhombohedral etch pits changed to hexagonal in the presence of fluoride in the undersaturated solutions. The AFM dissolution experiments suggested that the fluoride ions adsorbed onto the calcite surface. Further increase of fluoride concentrations (up to 1.6 mM) resulted in the decrease of the calcite dissolution rate by 60% in both [010] and [42] directions. Reference: Okumura, M, Kitano, Y

  7. Lithium niobate single-crystal and photo-functional device

    DOEpatents

    Gopalan, Venkatraman; Mitchell, Terrence E.; Kitamura, Kenji; Furukawa, Yasunori

    2001-01-01

    Provided are lithium niobate single-crystal that requires a low voltage of not larger than 10 kV/nm for its ferroelectric polarization inversion and of which the polarization can be periodically inverted with accuracy even at such a low voltage, and a photo-functional device comprising the crystal. The crystal has a molar fraction of Li.sub.2 O/(Nb.sub.2 O.sub.5 +Li.sub.2 O) of falling between 0.49 and 0.52. The photo-functional device can convert a laser ray being incident thereon.

  8. Note: Accuracy of velocity correction for impact of a laser-accelerated miniature flyer with lithium fluoride shock-compressed along the [100] axis

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Kunihiko; Matsumura, Tomoharu; Nakayama, Yoshio; Koshi, Mitsuo

    2011-02-01

    We performed miniature flyer impact experiments to investigate the relationship between the apparent (ua) and actual (uA) particle velocities measured by a velocity interferometer in single-crystal lithium fluoride (LiF) that was shock-compressed along the [100] axis. The miniature flyer was accelerated to velocities in the range 652.5-1937.6 m/s by a tabletop pulsed laser. An empirical relationship of ua = (1.2749 ± 0.0102)uA was obtained. The obtained relationship agreed well with the results of a previous study within the experimental errors and its uncertainty was less than ±1%. This result indicates that the present experimental technique is effective for measuring the relationship between ua and uA of shocked transparent materials with a comparable accuracy to conventional methods.

  9. Note: Accuracy of velocity correction for impact of a laser-accelerated miniature flyer with lithium fluoride shock-compressed along the [100] axis.

    PubMed

    Wakabayashi, Kunihiko; Matsumura, Tomoharu; Nakayama, Yoshio; Koshi, Mitsuo

    2011-02-01

    We performed miniature flyer impact experiments to investigate the relationship between the apparent (u(a)) and actual (u(A)) particle velocities measured by a velocity interferometer in single-crystal lithium fluoride (LiF) that was shock-compressed along the [100] axis. The miniature flyer was accelerated to velocities in the range 652.5-1937.6 m/s by a tabletop pulsed laser. An empirical relationship of u(a) = (1.2749 ± 0.0102)u(A) was obtained. The obtained relationship agreed well with the results of a previous study within the experimental errors and its uncertainty was less than ±1%. This result indicates that the present experimental technique is effective for measuring the relationship between u(a) and u(A) of shocked transparent materials with a comparable accuracy to conventional methods.

  10. Note: Accuracy of velocity correction for impact of a laser-accelerated miniature flyer with lithium fluoride shock-compressed along the [100] axis

    SciTech Connect

    Wakabayashi, Kunihiko; Matsumura, Tomoharu; Nakayama, Yoshio; Koshi, Mitsuo

    2011-02-15

    We performed miniature flyer impact experiments to investigate the relationship between the apparent (u{sub a}) and actual (u{sub A}) particle velocities measured by a velocity interferometer in single-crystal lithium fluoride (LiF) that was shock-compressed along the [100] axis. The miniature flyer was accelerated to velocities in the range 652.5-1937.6 m/s by a tabletop pulsed laser. An empirical relationship of u{sub a}= (1.2749 {+-} 0.0102)u{sub A} was obtained. The obtained relationship agreed well with the results of a previous study within the experimental errors and its uncertainty was less than {+-}1%. This result indicates that the present experimental technique is effective for measuring the relationship between u{sub a} and u{sub A} of shocked transparent materials with a comparable accuracy to conventional methods.

  11. Origin of electronic transport of lithium phthalocyanine iodine crystal

    SciTech Connect

    Koike, Noritake; Oda, Masato; Shinozuka, Yuzo

    2013-12-04

    The electronic structures of Lithium Phthalocyanine Iodine are investigated using density functional theory. Comparing the band structures of several model crystals, the metallic conductivity of highly doped LiPcI{sub x} can be explained by the band of doped iodine. These results reveal that there is a new mechanism for electronic transport of doped organic semiconductors that the dopant band plays the main role.

  12. Fluoride incorporation into apatite crystals delays amelogenin hydrolysis

    PubMed Central

    DenBesten, Pamela; Zhu, Li; Li, Wu; Tanimoto, Kotaro; Liu, Haichuan; Witkowska, Halina Ewa

    2012-01-01

    Enamel fluorosis has been related to an increase in the amount of amelogenin in fluorosed enamel as compared to normal enamel in the maturation stage. In this study we tested the hypothesis that fluoride incorporated into carbonated apatite alters amelogenin hydrolysis. Recombinant human amelogenin (rh174) was allowed to bind to 0.15 mg of carbonated hydroxyapatite (CAP) or fluoride-containing carbonated hydroxyapatite (F-CAP) synthesized to contain 100, 1000 or 4000 ppm F-. After 3 h digestion with recombinant human MMP20 or KLK4, bound protein was characterized by reverse-phase HPLC. Proteolytic fragments formed after 24 h digestion of amelogenin, were identified by LC tandem mass spectrometry (LCMS/MS). The hydrolysis of amelogenin bound to F100-CAP by both MMP20 and KLK4 was significantly reduced in a dose dependent manner as compared to CAP. After 24 h hydrolysis, the number of cleavage sites in bound amelogenin by MMP20 were similar in CAP and F100-CAP, whereas there were 24 fewer cleavage sites identified for the KLK4 hydrolysis on F100-CAP as compared to CAP. These results suggest that the reduced hydrolysis of amelogenins in fluorosed enamel may be partially due to the increased fluoride content in fluoride containing apatite, contributing to the hypomineralized enamel matrix phenotype observed in fluorosed enamel. PMID:22243219

  13. Origins of Large Voltage Hysteresis in High-Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes.

    PubMed

    Li, Linsen; Jacobs, Ryan; Gao, Peng; Gan, Liyang; Wang, Feng; Morgan, Dane; Jin, Song

    2016-03-01

    Metal fluorides and oxides can store multiple lithium ions through conversion chemistry to enable high-energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage profiles and the consequent low-energy efficiency (<80%). The physical origins of such hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy, transmission electron microscopy, density functional theory calculations, and galvanostatic intermittent titration technique to first correlate the voltage profile of iron fluoride (FeF3), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the FeF3 electrode is kinetic in nature. It is the result of ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically active phases (i.e., compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry.

  14. Effect of chloride incorporation on the crystallization of zirconium-barium-lanthanum-aluminum fluoride glass

    NASA Technical Reports Server (NTRS)

    Neilson, G. F.; Smith, G. L.; Weinberg, M. C.

    1985-01-01

    One aspect of the influence of preparation procedure on the crystallization behavior of a zirconium-barium-lanthanum-aluminum fluoride glass was studied. The crystallization pattern of this glass may be affected by the chlorine concentration within it. In particular, when such glasses are heated at low temperatures, the alpha-Ba-Zr-F6 crystalline phase forms only in those glasses which contain chloride.

  15. Characterization of the terbium-doped calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Zheleznov, Dmitry S.; Starobor, Aleksey V.; Palashov, Oleg V.

    2015-08-01

    Optical, thermo-optical and magneto-optical characteristics of the terbium-doped (10 at.%) calcium fluoride sample were investigated. It was made the analysis, confirmed the possibility of development of a Faraday isolator and a cryogenic Faraday isolator based on the studied medium, which will provide more than 30 dB isolation ratio of laser radiation in the "eye-safe" wavelength range (1530-1620 nm) at the 5 and 20 kW power, respectively.

  16. Measurement of the melting point temperature of several lithium-sodium-beryllium fluoride salt (FLINABE) mixtures.

    SciTech Connect

    Boyle, Timothy J.; Troncosa, Kenneth P.; Nygren, Richard Einar; Lutz, Thomas Joseph; McDonald, Jimmie M.; Tanaka, Tina Joan; Ulrickson, Michael Andrew

    2004-09-01

    The molten salt Flibe, a combination of lithium and beryllium flourides, was studied for molten salt fission reactors and has been proposed as a breeder and coolant for the fusion applications. 2LiF-BeF{sub 2} melts at 460 C. LiF-BeF{sub 2} melts at a lower temperature, 363 C, but is rather viscous and has less lithium breeder. In the Advanced Power Extraction (APEX) Program, concepts with a free flowing ternary molten salt for the first wall surface and blanket were investigated. The molten salt (FLiNaBe, a ternary mixture of LiF, BeF2 and NaF) salt was selected because a melting temperature below 350 C that would provide an attractive operating temperature window for a reactor application appeared possible. This information came from a Russian binary phase diagram and a US ternary phase diagram in the 1960's that were not wholly consistent. To confirm that a ternary salt with a low melting temperature existed, several combinations of the fluoride salts, LiF, NaF and, BeF{sub 2}, were melted in a small stainless steel crucible under vacuum. The proportions of the three salts were selected to yield conglomerate salts with as low a melting temperature as possible. The temperature of the salts and the crucible were recorded during the melting and subsequent re-solidification using a thermocouple directly in the salt pool and two thermocouples embedded in the crucible. One mixture had an apparent melting temperature of 305 C. Particular attention was paid to the cooling curve of the salt temperature to observe evidence of any mixed intermediate phases between the fully liquid and fully solid states. The clarity, texture, and thickness were observed and noted as well. The test system, preparation of the mixtures, and the melting procedure are described. The temperature curves for the melting and cooling of each of the mixtures are presented along with the apparent melting points. Thermal modeling of the salt pool and crucible was also done and is reported in a separate

  17. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  18. Determining the refractive index of shocked [100] lithium fluoride to the limit of transmissibility

    SciTech Connect

    Rigg, P. A. Scharff, R. J.; Hixson, R. S.; Knudson, M. D.

    2014-07-21

    Lithium fluoride (LiF) is a common window material used in shock- and ramp-compression experiments because it displays a host of positive attributes in these applications. Most commonly, it is used to maintain stress at an interface and velocimetry techniques are used to record the particle velocity at that interface. In this application, LiF remains transparent to stresses up to 200 GPa. In this stress range, LiF has an elastic-plastic response with a very low (<0.5 GPa) elastic precursor and exhibits no known solid-solid phase transformations. However, because the density dependence of the refractive index of LiF does not follow the Gladstone-Dale relation, the measured particle velocity at this interface is not the true particle velocity and must be corrected. For that reason, the measured velocity is often referred to as the apparent velocity in these types of experiments. In this article, we describe a series of shock-compression experiments that have been performed to determine the refractive index of LiF at the two most commonly used wavelengths (532 nm and 1550 nm) between 35 and 200 GPa to high precision. A modified form of the Gladstone-Dale relation was found to work best to fit the determined values of refractive index. In addition, we provide a direct relationship between the apparent and true particle velocity to correct experimentally obtained wave profiles by others using these velocimetry techniques.

  19. Crystal growth and characterization of γ-glycine grown from potassium fluoride for photonic applications

    NASA Astrophysics Data System (ADS)

    Dillip, G. R.; Raghavaiah, P.; Mallikarjuna, K.; Reddy, C. Madhukar; Bhagavannarayana, G.; Kumar, V. Ramesh; Raju, B. Deva Prasad

    2011-09-01

    Single crystals of γ-glycine, an organic nonlinear optical material have been synthesized in the presence of potassium fluoride (KF) by slow evaporation technique at ambient temperature. The size of the grown crystal is up to the dimension of 12 mm × 10 mm × 8 mm. The γ-phase was confirmed by single crystal X-ray diffraction, powder XRD and the FTIR analysis. Optical absorption spectrum reveals that the grown crystal has good optical transparency in the entire visible region with an energy band gap of 5.09 eV, which is an essential requirement for a nonlinear optical crystal. Thermal stability of the grown γ-glycine crystal was determined using the thermo gravimetric and differential thermal analyses. The NLO activity of γ-glycine was confirmed by the Kurtz powder technique using Nd:YAG laser and the grown crystal exhibits high relative conversion efficiency when compared to potassium dihydrogen phosphate (KDP).

  20. Isotope effects in lithium hydride and lithium deuteride crystals by molecular dynamics simulations.

    PubMed

    Dammak, Hichem; Antoshchenkova, Ekaterina; Hayoun, Marc; Finocchi, Fabio

    2012-10-31

    Molecular dynamics (MD) simulations have been carried out to study isotope effects in lithium hydride and lithium deuteride crystals. Quantum effects on nuclear motion have been included through a quantum thermal bath (QTB). The interatomic forces were described either within the density functional theory (DFT) in the generalized gradient approximation (GGA) or by the phenomenological approach using the shell model. For both models, the isotopic shift in the lattice parameter can be successfully predicted by QTB-MD simulations. The slope of the experimental isotopic shift in pressure is satisfactorily reproduced by QTB-MD within DFT-GGA, in contrast to both density functional perturbation theory and QTB-MD with the shell model. We have analyzed the reasons for these discrepancies through the vibrational densities of states and the isotopic shifts in bulk modulus. The results illustrate the importance of anharmonic contributions to vibrations and to the isotopic pressure shift between LiH and LiD.

  1. Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

    SciTech Connect

    None, None

    1999-10-04

    A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.

  2. Crystallization of lithium disilicate glass using variable frequency microwave processing

    NASA Astrophysics Data System (ADS)

    Mahmoud, Morsi Mohamed

    The lithium disilicate (LS2) glass system provides the basis for a large number of useful glass-ceramic products. Microwave processing of materials such as glass-ceramics offers unique benefits over conventional processing techniques. Variable frequency microwave (VFM) processing is an advanced processing technique developed to overcome the hot spot and the arcing problems in microwave processing. In general, two main questions are addressed in this dissertation: (1) How does microwave energy couple with a ceramic material to create heat? and, (2) Is there a "microwave effect" and if so what are the possible explanations for the existence of that effect? The results of the present study show that VFM processing was successfully used to crystallize LS2 glass at a frequency other than 2.45 GHz and without the aid of other forms of energy (hybrid heating). Crystallization of LS2 glass using VFM heating occurred in a significantly shorter time and at a lower temperature as compared to conventional heating. Furthermore, the crystallization mechanism of LS2 glass in VFM heating was not exactly the same as in conventional heating. Although LS2 crystal phase (Orthorhombic Ccc2) was developed in the VFM crystallized samples as well as in the conventionally crystallized samples as x-ray diffraction (XRD) confirmed, the structural units of SiO4 tetrahedra (Q species) in the VFM crystallized samples were slightly different than the ones in conventionally crystallized samples as the Raman spectroscopy revealed. Moreover, the observed reduction in the crystallization time and apparent temperature in addition to the different crystallization mechanism observed in the VFM process both provided experimental evidence to support the presence of the microwave effect in the LS2 crystallization process. Also, the molecular orbital model was successfully used to predict the microwave absorption in LS2 glass and glass-ceramic. This model was consistent with experiments and indicated that

  3. Effect of Fluoride on the Morphology of Calcium Phosphate Crystals Grown on Acid-Etched Human Enamel

    PubMed Central

    Fan, Y.; Sun, Z.; Moradian-Oldak, J.

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2–10 μm wide) were formed. With 1–10 mg/l fluoride, arrays of denser needle-like nanocrystals (20–30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro. PMID:19321991

  4. Neutron beam test of barium fluoride crystal for dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Guo, C.; Ma, X. H.; Wang, Z. M.; Bao, J.; Dai, C. J.; Guan, M. Y.; Liu, J. C.; Li, Z. H.; Ren, J.; Ruan, X. C.; Yang, C. G.; Yu, Z. Y.; Zhong, W. L.

    2016-10-01

    In order to test the capabilities of Barium Fluoride (BaF2) crystal for dark matter direct detection, nuclear recoils are studied with mono-energetic neutron beam. The energy spectra of nuclear recoils, quenching factors for elastic scattering neutrons and discrimination capability between neutron inelastic scattering events and γ events are obtained for various recoil energies of the F content in BaF2.

  5. Conductivity degradation of polyvinylidene fluoride composite binder during cycling: Measurements and simulations for lithium-ion batteries

    DOE PAGES

    Grillet, Anne M.; Humplik, Thomas; Stirrup, Emily K.; Roberts, Scott A.; Barringer, David A.; Snyder, Chelsea M.; Janvrin, Madison R.; Apblett, Christopher A.

    2016-07-02

    The polymer-composite binder used in lithium-ion battery electrodes must both hold the electrodes together and augment their electrical conductivity while subjected to mechanical stresses caused by active material volume changes due to lithiation and delithiation. We have discovered that cyclic mechanical stresses cause significant degradation in the binder electrical conductivity. After just 160 mechanical cycles, the conductivity of polyvinylidene fluoride (PVDF):carbon black binder dropped between 45–75%. This degradation in binder conductivity has been shown to be quite general, occurring over a range of carbon black concentrations, with and without absorbed electrolyte solvent and for different polymer manufacturers. Mechanical cycling ofmore » lithium cobalt oxide (LiCoO2) cathodes caused a similar degradation, reducing the effective electrical conductivity by 30–40%. Mesoscale simulations on a reconstructed experimental cathode geometry predicted the binder conductivity degradation will have a proportional impact on cathode electrical conductivity, in qualitative agreement with the experimental measurements. Lastly, ohmic resistance measurements were made on complete batteries. Direct comparisons between electrochemical cycling and mechanical cycling show consistent trends in the conductivity decline. This evidence supports a new mechanism for performance decline of rechargeable lithium-ion batteries during operation – electrochemically-induced mechanical stresses that degrade binder conductivity, increasing the internal resistance of the battery with cycling.« less

  6. Photorefractive properties of near-stoichiometric lithium niobate crystals doped with iron

    NASA Astrophysics Data System (ADS)

    Liu, Hongde; Xie, Xiang; Kong, Yongfa; Yan, Wenbo; Li, Xiaochun; Shi, Lihong; Xu, Jingjun; Zhang, Guangyin

    2006-02-01

    Near-stoichiometric lithium niobate crystals doped with iron were prepared by vapor transport equilibration (VTE) method. The gain coefficient of these samples were measured and compared to the near-stoichiometric lithium niobate crystals prepared by double-crucible method, and the diffraction efficiency, recording time and erasing time were also done. The dynamic range coefficient (M/#) and homogeneity of the composition in the crystals were investigated too.

  7. Single crystal structures of thallium (I) thorium fluorides and crystal chemistry of monovalent tetravalent cation pentafluorides

    NASA Astrophysics Data System (ADS)

    Oudahmane, Abdelghani; El-Ghozzi, Malika; Jouffret, Laurent; Avignant, Daniel

    2015-12-01

    Two thallium (I) thorium (IV) fluorides, TlTh3F13 and TlThF5 were obtained by solid state synthesis and their crystal structures determined from single crystal X-ray diffraction data recorded at room temperature with an APEX-II CCD diffractometer. TlTh3F13 is orthorhombic, space group Pmc21, with a=8.1801(2) Å, b=7.4479(2) Å, c=8.6375(2) Å, V=526.24(2) Å3, Z=2 and TlThF5 is monoclinic, space group P21/n, with a=8.1128(5) Å, b=7.2250(4) Å, c=8.8493(6) Å, β=116.683(3)°, V=463.46(5) Å3, Z=4. The structure of TlTh3F13 comprises layers of corner and edge-sharing ThF9 polyhedra further linked by chains of trans connected tricapped trigonal prisms ThF9 through corners and edges. The three dimensional thorium frameworks delimits channels parallel to [0 0 1] where the 11-coordinated Tl+ ions are arranged into double columns located in mirror planes of the structure. TlTh3F13 is isotypic with RbTh3F13, RbU3F13 and with one of the two polymorphs of CsTh3F13. The structure of TlThF5 may be regarded as a layer structure built up from the regular succession of 2∞[ M ‧F5 ] - corrugated layers further held by the Tl+ ions along the [1 0 1 ̅] direction. The layers are built up from edge and corner-sharing thorium polyhedra where each (ThF9)5- monocapped square antiprism is connected to five others by sharing three edges and two corners. TlThF5 is isostructural with β-NH4UF5 and with one of the polymorphs of CsThF5. A comparison of the different structural types of MM‧F5 pentafluorides is presented and a diagram of repartition of their structures is given. From the comparison of the Tl structures with their Rb or Cs homologs, where very similar monovalent cation environments are observed it should be concluded to a stereochemically inactivity of the 6s2 lone pair of Tl(I) in both TlTh3F13 and TlThF5, contrary to what is observed in richer Tl(I) content Tl3ThF7 fluorothorate.

  8. Electrical conduction in nanodomains in congruent lithium tantalate single crystal

    SciTech Connect

    Cho, Yasuo

    2014-01-27

    The electrical current flow behavior was investigated for nanodomains formed in a thin congruent lithium tantalate (LiTaO{sub 3}) single-crystal plate. When the nanodomains were relatively large, with diameters of about 100 nm, current flow was detected along the domain wall. However, when they were about 40 nm or smaller, the current flowed through the entire nanodomain. Schottky-like rectifying behavior was observed. Unlike the case of LiNbO{sub 3}, optical illumination was not required for current conduction in LiTaO{sub 3}. A clear temperature dependence of the current was found indicating that the conduction mechanism for nanodomains in LiTaO{sub 3} may involve thermally activated carrier hopping.

  9. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect

    Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  10. Nanofiller incorporated poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) composite electrolytes for lithium batteries

    NASA Astrophysics Data System (ADS)

    Manuel Stephan, A.; Nahm, Kee Suk; Prem Kumar, T.; Kulandainathan, M. Anbu; Ravi, G.; Wilson, J.

    Composite polymer electrolyte (CPE) membranes, comprising poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), aluminum oxyhydroxide (AlO[OH] n) of two different sizes 7 μm/14 nm and LiN(C 2F 5SO 2) 2 as the lithium salt were prepared using a solution casting technique. The prepared membranes were subjected to XRD, impedance spectroscopy, compatibility and transport number studies. Also Li Cr 0.01Mn 1.99O 4/CPE/Li cells were assembled and their charge-discharge profiles made at 70 °C. The incorporation of nanofiller greatly enhanced the ionic conductivity and the compatibility of the composite polymer electrolyte. The film which possesses a nanosized filler offered better electrochemical properties than a film with micron sized fillers. The results are discussed based on Lewis acid-base theory.

  11. Mode-locking optimization with a real-time feedback system in a Nd:yttrium lithium fluoride laser cavity.

    PubMed

    Marengoni, C; Canova, F; Batani, D; Benocci, R; Librizzi, M; Narayanan, V; Gomareschi, M; Lucchini, G; Kilpio, A; Shashkov, E; Stuchebrukhov, I; Vovchenko, V; Chernomyrdin, V; Krasuyk, I; Hall, T; Bittanti, S

    2007-01-01

    We present a control system, which allows an automatic optimization of the pulse train stability in a mode-locked laser cavity. In order to obtain real-time corrections, we chose a closed loop approach. The control variable is the cavity length, mechanically adjusted by gear system acting on the rear cavity mirror, and the controlled variable is the envelope modulation of the mode-locked pulse train. Such automatic control system maintains the amplitude of the mode-locking pulse train stable within a few percent rms during the working time of the laser. Full implementation of the system on an Nd:yttrium lithium fluoride actively mode-locked laser is presented.

  12. Interatomic radiative transition rates for the sodium fluoride crystal

    SciTech Connect

    Green, T.A.; Jennison, D.R.

    1988-03-15

    Interatomic electric-dipole radiative transition rates for the NaF crystal are calculated for initial 1s, 2s, and 2p holes in the Na/sup +/ ion. The crystal is simulated by a (NaF/sub 6/)/sup 5 -/ cluster embedded in a large number of point ions, and the one-electron molecular orbitals are obtained from open-shell restricted-Hartree-Fock calculations of the initial state and final states. This allows the transition matrix element to be calculated in the self-consistent-field (..delta..SCF) formalism where both initial- and final-state determinantal wave functions are used, and the nonorthogonality of the two sets of molecular orbitals is taken into account. One interatomic radiative transition, the K..beta../sub 1/ satellite line, has been observed as a high-energy satellite of the Na K..cap alpha../sub 1/..cap alpha../sub 2/ line. The measured intensity ratio ..beta../sub 1/..cap alpha../sub 1/..cap alpha../sub 2/ is 1.2 x 10/sup -2/;our theoretical ratio is 1.13 x 10/sup -2/. This level of agreement between theory and experiment is similar to, but somewhat better than, that recently obtained by us for interatomic Auger transitions in NaF, using molecular orbitals from the same calculations. The other interatomic radiative transitions in NaF have considerably smaller transition energies and unobservably small transition rates. The sensitivity of the rates to the choice of Hartree-Fock Gaussian basis set is explored. Rates based on a single determinantal wave function are compared with the ..delta..SCF rates. The one-center approximation for the K..beta../sub 1/ rate was found to account for 82% of the rate

  13. [Study on Spectral Characteristics of Two Kinds of Home-Made Novel Yb-Doped Fluoride Laser Crystals].

    PubMed

    Xu, Wen-bin; Chai, Lu; Shi, Jun-kai; Song, You-jian; Hu, Ming-lie; Wang, Qing-yue; Su, Liang-bi; Jiang, Da-peng; Xu, Jun

    2015-09-01

    Yb-doped fluoride crystals are of important another Yb-doped laser materials besides Yb-doped oxide, which are becoming one of interests for developing tunable lasers and ultrafast lasers. In this paper, the systematic and contrastive experiments of the optical spectral characteristics are presented for two types of home-made novel Yb-doped fluoride laser crystals, namely, Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal. The fluorescent features of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal are apparently different by the fluorescence experiment. The physical mechanism of these fluorescence spectra were analyzed and proposed. The influence of doping concentrations of active Yb(3+) ions or co-doping Y ions on the absorption of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal was experimentally investigated, and the optimal values of doping concentrations of active Yb(3+) ions or co-doping Y ions in the two types of fluoride laser crystals were obtained. Continuous-wave laser operation for the two novel fluoride laser crystals has been achieved in three-mirror-folded resonator using a laser diode as the pump source. Therein, the laser operation for the co-doped Yb, Y:CaF2 crystal is demonstrated for the first time. For the two types of fluoride laser crystals (four samples), the input-output power relational curves, the optical slope efficiencies and the laser spectra were demonstrated by the laser experiments. By comparisons between the two types of fluoride laser crystals in the absorbability, fluorescence and laser spectra, laser threshold and slope efficiency of the continuous-wave laser operation, the results show that the best one of the four samples in spectral and laser characteristics is co-doped 3at%Yb, 6at% Y:CaF2 single crystal, which has an expected potential in the application. The research results provide available references for improving further laser performance of Yb

  14. In-Situ Crystallization of a Lithium Disilicate Glass--Effect of Pressure on Crystal Growth Rate

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Ray, C. S.; Lesher, C. E.; Day, D. E.

    2006-01-01

    Crystallization of a Li2O.2SiO2 (LS2) glass subjected to a uniform hydrostatic pressure of 4.5 GPa and 6 GPa was investigated up to a temperature of 750 C. The density of the compressed glass is about 2% greater at 4.5 GPa than at 1 atm and, depending upon the processing temperature, up to 10% greater at 6 GPa. Crystal growth rates investigated as a function of temperature and pressure show that lithium disilicate crystal growth is an order of magnitude slower at 4.5 GPa than 1 atm resulting in a shift of +45 C (plus or minus 10 C) in the growth rate curve at high pressure compared to 1 atm condition. At 6 GPa lithium disilicate crystallization is suppressed entirely, while a new high pressure lithium metasilicate crystallizes at temperatures 95 C (plus or minus 10 C) higher than those reported for lithium disilicate crystallization at 1 atm. The decrease in crystal growth rate with increasing pressure for lithium disilicate glass up to 750 C is related to an increase in viscosity with pressure associated with fundamental changes in glass structure accommodating densification.

  15. Refinement of the crystal structure of lithium-bearing uvite

    SciTech Connect

    Rozhdestvenskaya, I. V. Frank-Kamenetskaya, O. V.; Kuznetsova, L. G.; Bannova, I. I.; Bronzova, Yu. M.

    2007-03-15

    The crystal structure of a natural calcium tourmaline, i.e., uvite with a high lithium content (0.51 au per formula (aupf) at the Y site, is refined to R = 0.019, R{sub w} = 0.020, and S = 1.11. It is shown that, in nature, there exist uvites in which the charge balance in the case where the Z site is occupied by trivalent cations is provided by the replacement of part of the divalent magnesium cations at the Y site by univalent cations, divalent calcium cations at the X site by sodium cations, and univalent anions at the W site by oxygen anions. The W site is found to be split into two sites, namely, the W1 and W11 sites (the W1-W11 distance is 0.14 A), which are partially occupied by the fluorine and oxygen anions, respectively. An analysis of the results obtained in this study and the data available in the literature on the crystal structure of uvites allows the conclusion that uvite can be considered a superspecies and that the nomenclature of this mineral group needs refinement with the use of structural data.

  16. On the existence of "L-threonine formate", "L-alanine lithium chloride" and "bis L-alanine lithium chloride" crystals.

    PubMed

    Petrosyan, A M; Ghazaryan, V V; Fleck, M

    2013-03-15

    We argue that the recently reported crystals "L-threonine formate" as well as "L-alanine lithium chloride" and "bis L-alanine lithium chloride" actually are the well-known crystals L-threonine and L-alanine, respectively.

  17. Growth and characterization of Cu (II) doped negatively soluble lithium sulfate monohydrate crystals

    NASA Astrophysics Data System (ADS)

    Boopathi, K.; Ramasamy, P.; Bhagavannarayana, G.

    2014-01-01

    Single crystals of pure and Cu (II) doped negatively soluble lithium sulfate monohydrate have been grown by slow evaporation solution technique. In the present work, to improve the crystalline quality of lithium sulfate monohydrate crystal, metal dopant was incorporated into the pure crystals. The as grown crystals are clear, transparent and the sizes of the crystals were up to 18×12×3 mm3 and 50×15×5 mm3. The presence of metal dopant has been confirmed by energy dispersive spectroscopy, atomic absorption spectroscopy analysis. Single crystal and powder X-ray diffraction studies were carried out to ascertain lattice parameters and identify different phase nature. Optical transmission spectrum of the grown crystals was recorded. FT-IR and thermal analysis were carried out to investigate the functional group and thermal behavior of the grown crystals respectively. The grown crystal was subjected to Vickers micro hardness, HRXRD, piezoelectric, laser damage threshold measurements and second harmonic generation efficiency studies.

  18. The Effects of Gravity on the Crystallization Behavior of Heavy Metal Fluoride Glasses

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Smith, Guy A.

    2004-01-01

    Heavy metal fluoride glasses are used in such applications as fiber lasers and laser amplifiers. ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) is one of the more commonly used heavy metal fluoride glasses. ZBLAN is an infrared transmitter and has a theoretical attenuation coefficient of 0.002 db/km. However, due to impurities and small crystallites this attenuation coefficient has not been achieved to date. ZBLAN is a fragile glass which can lead to rapid crystallization, if the glass is not cooled rapidly to below the glass transition temperature or if the glass is reheated near the crystallization temperature for any period of time. Studies carried on at Marshall Space Flight Center and the University of Alabama in Huntsville since 1993 have shown that heating ZBLAN glass at the crystallization temperature in reduced gravity results in a suppression of crystallization when compared to ZBLAN processed in unit gravity. These studies utilized NASA's KC-135 aircraft and the Conquest sounding rocket. In the first series of experiments, short lengths of ZBLAN fiber were heated to the crystallization temperature in reduced gravity on board the KC- 135 and the Conquest sounding rocket and compared with fibers heated in unit gravity. The fibers processed in reduced gravity showed no evidence of crystallization when studied with x-ray diffraction and scanning electron microscopy. However, the fibers processed in unit gravity were completely crystallized. Subsequent experiments included heating small pieces of ZBLAN glass at the crystallization temperature while viewing with a video camera to follow the crystallization phenomenon. In this experiment crystallization was observed in reduced gravity, however, it was suppressed when compared to heating in unit gravity. In the most recent experiment on board the KC-135, rapid thermal analysis of ZBLAN was performed. A mechanism to explain the observations has been proposed. This mechanism is based on shear thinning whereby, the glass

  19. Fluoride Binding and Crystal-Field Analysis of Lanthanide Complexes of Tetrapicolyl-Appended Cyclen.

    PubMed

    Blackburn, Octavia A; Kenwright, Alan M; Jupp, Andrew R; Goicoechea, Jose M; Beer, Paul D; Faulkner, Stephen

    2016-06-20

    Lanthanide complexes of tetrapicolyl cyclen displayed remarkably high affinities for fluoride (log K≈5) in water, and were shown to form 1:1 complexes. The behaviour of these systems can be rationalised by changes to the magnitude of the crystal-field parameter, B20 . However, such changes are not invariably accompanied by a change in sign of this parameter: for early lanthanides, the N8 donor set with a coordinated axial water molecule ensures that the magnetic anisotropy has the opposite sense to that observed in the analogous dehydrated lanthanide complexes. PMID:27167830

  20. Twin defects in thick stoichiometric lithium tantalate crystals prepared by a vapor transport equilibration method

    NASA Astrophysics Data System (ADS)

    Yang, Jinfeng; Sun, Jun; Xu, Jingjun; Li, Qinglian; Shang, Jifang; Zhang, Ling; Liu, Shiguo; Huang, Cunxin

    2016-01-01

    The twins were observed and investigated in vapor transport equilibration (VTE) treated lithium tantalate crystals by burying congruent lithium tantalate crystals (CLT) in a Li-rich polycrystalline powder. Twins and their etched patterns were observed under an optical polarizing microscope, and the geometry of the twins was discussed. Twin composition planes were the { 01 1 bar 2 } planes. The cause of twinning was analyzed and verified by experiment. The results indicate that the emergence of twins is due to sintering stress, which arises from sintered Li-rich polycrystalline powders at high temperature. 3.2 mm thick stoichiometric lithium tantalate (SLT) crystals without twins were obtained by setting corundum crucibles over the top of the crystals to make crystals free from the sintering stress. In addition, cracks were observed at the intersection of twin bands, and the stress caused by the dislocation pile-up was considered to be the reason for the formation of cracks.

  1. Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range.

    PubMed

    Wu, Xiaojun; Zhou, Chun; Huang, Wenqian Ronny; Ahr, Frederike; Kärtner, Franz X

    2015-11-16

    Optical rectification with tilted pulse fronts in lithium niobate crystals is one of the most promising methods to generate terahertz (THz) radiation. In order to achieve higher optical-to-THz energy efficiency, it is necessary to cryogenically cool the crystal not only to decrease the linear phonon absorption for the generated THz wave but also to lengthen the effective interaction length between infrared pump pulses and THz waves. However, the refractive index of lithium niobate crystal at lower temperature is not the same as that at room temperature, resulting in the necessity to re-optimize or even re-build the tilted pulse front setup. Here, we performed a temperature dependent measurement of refractive index and absorption coefficient on a 6.0 mol% MgO-doped congruent lithium niobate wafer by using a THz time-domain spectrometer (THz-TDS). When the crystal temperature was decreased from 300 K to 50 K, the refractive index of the crystal in the extraordinary polarization decreased from 5.05 to 4.88 at 0.4 THz, resulting in ~1° change for the tilt angle inside the lithium niobate crystal. The angle of incidence on the grating for the tilted pulse front setup at 1030 nm with demagnification factor of -0.5 needs to be changed by 3°. The absorption coefficient decreased by 60% at 0.4 THz. These results are crucial for designing an optimum tilted pulse front setup based on lithium niobate crystals.

  2. Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

    NASA Astrophysics Data System (ADS)

    Silambarasan, A.; Rajesh, P.; Ramasamy, P.

    2015-06-01

    The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

  3. Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

    SciTech Connect

    Silambarasan, A.; Rajesh, P. Ramasamy, P.

    2015-06-24

    The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

  4. Impact of Nanosilicates on Poly(vinylidene fluoride) Crystal Polymorphism: Part 1. Melt-crystallization at High Supercooling

    SciTech Connect

    Ince-Gunduz, B.; Alpern, R; Amare, D; Crawford, J; Dolan, B; Jones, S; Kobylarz, R; Reveley, M; Cebe, P

    2010-01-01

    Polymorphism of poly(vinylidene fluoride), PVDF, in the presence of Lucentite STN organically modified silicate (OMS) is investigated for PVDF nanocomposites melt-crystallized at high supercooling temperatures where neat PVDF crystallizes exclusively in the alpha crystalline phase. Nanocomposites were prepared from solution with 0-1.0 wt% OMS composition. Here we observed that clay addition promotes gamma phase formation in nanocomposites melt-crystallized at high supercooling (i.e., at low crystallization temperature), whereas previously we showed that even small amount of nanosilicates resulted in beta phase formation in cold-crystallized PVDF nanocomposites. Wide-angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) studies showed that {alpha}- and {gamma}-phases co-existed in nanocomposites containing up to 0.1 wt% OMS, and the amount of {alpha}-crystals substantially diminished for higher OMS content. Formation of {gamma}-crystal phase was confirmed with morphologic observation of spherulites of low-birefringence using polarizing optical and atomic force microscopies, and their crystalline structures were verified by FTIR and Raman microscopic spectroscopy. We also address in this work the ambiguities in assessing PVDF crystallographic phases, and correct the phase identification errors which have persisted up to this point in the literature based on melting point confusion. The crystal phase identification for PVDF nanocomposites is discussed and clarified, based on X-ray scattering, vibrational spectra, and thermal analysis. For reference, we provide a vibrational band list, indicating the close, or overlapping bands, of the three phases of PVDF: {alpha}, {beta} and {gamma}.

  5. Hydrothermal Synthesis and Crystal Structure of a New Sodium Yttrium Fluoride Phosphate NaYFPO

    SciTech Connect

    Zhizhin, M. G.; Olenev, A. V.; Spiridonov, F. M.; Komissarova, L. N.; D'yachenko, O. G.

    2001-02-15

    The new compound NaYFPO{sub 4} has been synthesized by the hydrothermal method (T=200 C, p=20 bar, {tau}=300 h). It crystallizes in the monoclinic system (space group C2/m (No. 12)) with the unit cell parameters a=8.944(2) {angstrom}, b=6.930(1) {angstrom}, c=6.469(1) {angstrom}, {beta}=106.11(3){degree}, Z=4. Its structure has been determined from single-crystal X-ray diffraction data and refined to a conventional R{sub I}=0.0244 (wR{sub 2}=0.0629) for 358 reflections, with F{sub o}>4{sigma}(F{sub o}). The new fluoride phosphate NaYFPO{sub 4} has an original structure with its own structure type. The YO{sub 6}F{sub 2} polyhedra form infinite chains along [010] by sharing two oxygen atoms, which is the unique crystallographic feature of this fluoride phosphated compound. The chains are further linked by the fluorine edges of the YO{sub 6}F{sub 2} polyhedra in such a way that, within each chain, the polyhedra alternately have common fluorine atoms with the neighboring chains to their left and right.

  6. Ferroelectric properties of vinylidene fluoride/tetrafluoroethylene copolymer thin films consisting of needle-like crystals

    NASA Astrophysics Data System (ADS)

    Nakagawa, Yuuta; Hashizume, Yoichiro; Nakajima, Takashi; Okamura, Soichiro

    2016-05-01

    Unique ferroelectric vinylidene fluoride (VDF)/tetrafluoroethylene (TeFE) copolymer thin films consisting of needle-like crystals were formed using Au-sputtered substrates. The VDF/TeFE films with a mixing ratio of 80:20 mol % were melted at 170 °C for 30 min and then recrystallized at 116 °C for 300 min. The molecules in the resultant needle-like crystals had a β-phase form and showed 200/110 orientation, while the direction of each needle-like crystal was random in-plane. The remanent polarization of the 450-nm-thick VDF/TeFE films consisting of the needle-like crystals were estimated to be 62 mC/m2 from the electric displacement vs electric field (D–E) hysteresis measurement at the applied field of 156 MV/m and the frequency of 10 Hz. The remanent polarization of 62 mC/m2 was approximately 50% larger than that of conventional VDF/TeFE films consisting of plate-like crystals.

  7. Positioning Vise for Crystal Cleavage

    NASA Technical Reports Server (NTRS)

    Hallberg, F. C.; Morgan, C. J.

    1984-01-01

    Vise manipulates brittle crystals, such as lithium fluoride, so they are in proper position for cleaving. Vise allows crystals as thin as 2 millimeters or less positioned so that cleaved without breakage. Vise holds workpiece firmly but gently. Bushings, shafts and adjusting screw designed to move jaws smoothly and uniformly with great tactile sensitivity.

  8. Sulfonic Acid- and Lithium Sulfonate-Grafted Poly(Vinylidene Fluoride) Electrospun Mats As Ionic Liquid Host for Electrochromic Device and Lithium-Ion Battery.

    PubMed

    Zhou, Rui; Liu, Wanshuang; Leong, Yew Wei; Xu, Jianwei; Lu, Xuehong

    2015-08-01

    Electrospun polymer nanofibrous mats loaded with ionic liquids (ILs) are promising nonvolatile electrolytes with high ionic conductivity. The large cations of ILs are, however, difficult to diffuse into solid electrodes, making them unappealing for application in some electrochemical devices. To address this issue, a new strategy is used to introduce proton conduction into an IL-based electrolyte. Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) copolymer is functionalized with sulfonic acid through covalent attachment of taurine. The sulfonic acid-grafted P(VDF-HFP) electrospun mats consist of interconnected nanofibers, leading to remarkable improvement in dimensional stability of the mats. IL-based polymer electrolytes are prepared by immersing the modified mats in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)). It is found that the SO3(-) groups can have Lewis acid-base interactions with the cations (BMIM(+)) of IL to promote the dissociation of ILs, and provide additional proton conduction, resulting in significantly improved ionic conductivity. Using this novel electrolyte, polyaniline-based electrochromic devices show higher transmittance contrast and faster switching behavior. Furthermore, the sulfonic acid-grafted P(VDF-HFP) electrospun mats can also be lithiated, giving additional lithium ion conduction for the IL-based electrolyte, with which Li/LiCoO2 batteries display enhanced C-rate performance.

  9. Etching study of poled lithium tantalate crystal using wet etching technique with ultrasonic assistance

    NASA Astrophysics Data System (ADS)

    Gao, Z. D.; Wang, Q. J.; Zhang, Y.; Zhu, S. N.

    2008-02-01

    Utilizing the difference in etching rates of the positive and negative domains in an acid solution, domain pattern can be fabricated on the polarity surface of a congruent lithium tantalate crystal. Our results show that the ultrasonic agitation can improve the etching rate. An enhanced factor up to six was realized under a 50 W of ultrasonic power in a mixture with volumetric ratio of HF to H 2SO 4 at 1:2. The dependences of etching morphology on etching time and etching etchant for congruent lithium tantalate crystal were studied. The technique is applicable to fabricating three-dimensional microstructures on the surface of ferroelectric crystals.

  10. Mesoporous NiO crystals with dominantly exposed {110} reactive facets for ultrafast lithium storage

    PubMed Central

    Su, Dawei; Ford, Mike; Wang, Guoxiu

    2012-01-01

    Faceted crystals with exposed highly reactive planes have attracted intensive investigations for applications such as hydrogen production, enhanced catalytic activity, and electrochemical energy storage and conversion. Herein, we report the synthesis of mesoporous NiO crystals with dominantly exposed {110} reactive facets by the thermal conversion of hexagonal Ni(OH)2 nanoplatelets. When applied as anode materials in lithium-ion batteries, mesoporous NiO crystals exhibit a high reversible lithium storage capacity of 700 mAh g−1 at 1 C rate in 100 cycles and an excellent cyclability. In particular, the dominantly exposed {110} reactive facets and mesoporous nanostructure of NiO crystals lead to ultrafast lithium storage, which mimics the high power delivery of supercapacitors. PMID:23226591

  11. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2010-01-01

    In 2009, lithium consumption in the United States was estimated to have been about 1.2 kt (1,300 st) of contained lithium, a 40-percent decrease from 2008. The United States was estimated to be the fourth largest consumer of lithium, and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. Only one company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic resources. In 2009, world lithium consumption was estimated to have been about 18.7 kt (20,600 st) of lithium contained in minerals and compounds.

  12. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2011-01-01

    In 2010, lithium consumption in the United States was estimated to have been about 1 kt (1,100 st) of contained lithium, a 23-percent decrease from 2009. The United States was estimated to be the fourth largest consumer of lithium. It remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. Only one company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic resources. In 2010, world lithium consumption was estimated to have been about 21 kt (22,000 st) of lithium contained in minerals and compounds, a 12-percent increase from 2009.

  13. Instability of Polyvinylidene Fluoride-Based Polymeric Binder in Lithium-Ion Cells: Final Report

    SciTech Connect

    Garcia, M.; Nagasubramanian, G.; Tallant, D.R.; Roth, E.P.

    1999-05-01

    Thermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100 degree C involving the solid electrolyte interface (SEI) layer and the LiPF(6) salt in the electrolyte (EC-PC:DEC/IM LiPF(6)). These reactions could account for the thermal runaway observed in these cells beginning at 100 degree C. Exothermic reactions were also observed in the 200 degree C to 300 degree C region between the intercalated lithium anodes, the LiPF(6) salt, and the PVDF. These reactions were followed by a high-temperature reaction region, 300 degree C to 400 degree C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medium. Cathode exothermic reactions with the PVDF binder were observed above 200 degree C and increased with the state of charge (decreasing Li content). The stability of the PVDF binder as a function of electrochemical cycling was studied using FTIR. The infrared spectra from the extracts of both electrodes indicate that PVDF is chemically modified by exposure to the lithium cell electrolyte (as well as electrochemical cycling) in conjunction with NMP extraction. Preconditioning of PVDF to dehydrohalogenation, which may be occurring by reaction with LiPf(6), makes the PVDF susceptible to attack by a range of nucleophiles.

  14. Crystal and electronic structures of neptunium nitrides synthesized using a fluoride route.

    PubMed

    Silva, G W Chinthaka; Weck, Philippe F; Kim, Eunja; Yeamans, Charles B; Cerefice, Gary S; Sattelberger, Alfred P; Czerwinski, Kenneth R

    2012-02-15

    A low-temperature fluoride route was utilized to synthesize neptunium mononitride, NpN. Through the development of this process, two new neptunium nitride species, NpN(2) and Np(2)N(3), were identified. The NpN(2) and Np(2)N(3) have crystal structures isomorphous to those of UN(2) and U(2)N(3), respectively. NpN(2) crystallizes in a face-centered cubic CaF(2)-type structure with a space group of Fm3m and a refined lattice parameter of 5.3236(1) Å. The Np(2)N(3) adopts the body-centered cubic Mn(2)O(3)-type structure with a space group of Ia3. Its refined lattice parameter is 10.6513(4) Å. The NpN synthesis at temperatures ≤900 °C using the fluoride route discussed here was also demonstrated. Previous computational studies of the neptunium nitride system have focused exclusively on the NpN phase because no evidence was reported experimentally on the presence of NpN(x) systems. Here, the crystal structures of NpN(2) and Np(2)N(3) are discussed for the first time, confirming the experimental results by density functional calculations (DFT). These DFT calculations were performed within the local-density approximation (LDA+U) and the generalized-gradient approximation (GGA+U) corrected with an effective Hubbard parameter to account for the strong on-site Coulomb repulsion between Np 5f electrons. The effects of the spin-orbit coupling in the GGA+U calculations have also been investigated for NpN(2) and NpN.

  15. Crystal and Electronic Structures of Neptunium Nitrides Synthesized Using a Fluoride Route

    SciTech Connect

    Silva, G W Chinthaka M; Weck, Dr. Phil F.; Eunja, Dr. Kim; Yeamans, Dr. Charles B.; Cerefice, Gary S.; Sattelberger, Alfred P; Czerwinski, Ken R.

    2012-01-01

    A low-temperature fluoride route was utilized to synthesize neptunium mononitride, NpN. Through the development of this process, two new neptunium nitride species, NpN{sub 2} and Np{sub 2}N{sub 3}, were identified. The NpN{sub 2} and Np{sub 2}N{sub 3} have crystal structures isomorphous to those of UN{sub 2} and U{sub 2}N{sub 3}, respectively. NpN{sub 2} crystallizes in a face-centered cubic CaF{sub 2}-type structure with a space group of Fm3m and a refined lattice parameter of 5.3236(1) {angstrom}. The Np{sub 2}N{sub 3} adopts the body-centered cubic Mn{sub 2}O{sub 3}-type structure with a space group of Ia{bar 3}. Its refined lattice parameter is 10.6513(4) {angstrom}. The NpN synthesis at temperatures {le} 900 C using the fluoride route discussed here was also demonstrated. Previous computational studies of the neptunium nitride system have focused exclusively on the NpN phase because no evidence was reported experimentally on the presence of NpN{sub x} systems. Here, the crystal structures of NpN{sub 2} and Np{sub 2}N{sub 3} are discussed for the first time, confirming the experimental results by density functional calculations (DFT). These DFT calculations were performed within the local-density approximation (LDA+U) and the generalized-gradient approximation (GGA+U) corrected with an effective Hubbard parameter to account for the strong on-site Coulomb repulsion between Np 5f electrons. The effects of the spin-orbit coupling in the GGA+U calculations have also been investigated for NpN{sub 2} and NpN.

  16. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

    PubMed Central

    Liu, Jie; Lu, Xiaolong; Wu, Chunrui

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

  17. Low operating voltage n-channel organic field effect transistors using lithium fluoride/PMMA bilayer gate dielectric

    SciTech Connect

    Kumar, S.; Dhar, A.

    2015-10-15

    Highlights: • Alternative to chemically crosslinking of PMMA to achieve low leakage in provided. • Effect of LiF in reducing gate leakage through the OFET device is studied. • Effect of gate leakage on transistor performance has been investigated. • Low voltage operable and low temperature processed n-channel OFETs were fabricated. - Abstract: We report low temperature processed, low voltage operable n-channel organic field effect transistors (OFETs) using N,N′-Dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C{sub 8}) organic semiconductor and poly(methylmethacrylate) (PMMA)/lithium fluoride (LiF) bilayer gate dielectric. We have studied the role of LiF buffer dielectric in effectively reducing the gate leakage through the device and thus obtaining superior performance in contrast to the single layer PMMA dielectric devices. The bilayer OFET devices had a low threshold voltage (V{sub t}) of the order of 5.3 V. The typical values of saturation electron mobility (μ{sub s}), on/off ratio and inverse sub-threshold slope (S) for the range of devices made were estimated to be 2.8 × 10{sup −3} cm{sup 2}/V s, 385, and 3.8 V/decade respectively. Our work thus provides a potential substitution for much complicated process of chemically crosslinking PMMA to achieve low leakage, high capacitance, and thus low operating voltage OFETs.

  18. Photoluminescence of radiation-induced color centers in lithium fluoride thin films for advanced diagnostics of proton beams

    SciTech Connect

    Piccinini, M. Ampollini, A.; Picardi, L.; Ronsivalle, C.; Bonfigli, F.; Libera, S.; Vincenti, M. A.; Montereali, R. M.; Ambrosini, F.; Nichelatti, E.

    2015-06-29

    Systematic irradiation of thermally evaporated 0.8 μm thick polycrystalline lithium fluoride films on glass was performed by proton beams of 3 and 7 MeV energies, produced by a linear accelerator, in a fluence range from 10{sup 11} to 10{sup 15} protons/cm{sup 2}. The visible photoluminescence spectra of radiation-induced F{sub 2} and F{sub 3}{sup +} laser active color centers, which possess almost overlapping absorption bands at about 450 nm, were measured under laser pumping at 458 nm. On the basis of simulations of the linear energy transfer with proton penetration depth in LiF, it was possible to obtain the behavior of the measured integrated photoluminescence intensity of proton irradiated LiF films as a function of the deposited dose. The photoluminescence signal is linearly dependent on the deposited dose in the interval from 10{sup 3} to about 10{sup 6 }Gy, independently from the used proton energies. This behavior is very encouraging for the development of advanced solid state radiation detectors based on optically transparent LiF thin films for proton beam diagnostics and two-dimensional dose mapping.

  19. Photoluminescence of radiation-induced color centers in lithium fluoride thin films for advanced diagnostics of proton beams

    NASA Astrophysics Data System (ADS)

    Piccinini, M.; Ambrosini, F.; Ampollini, A.; Picardi, L.; Ronsivalle, C.; Bonfigli, F.; Libera, S.; Nichelatti, E.; Vincenti, M. A.; Montereali, R. M.

    2015-06-01

    Systematic irradiation of thermally evaporated 0.8 μm thick polycrystalline lithium fluoride films on glass was performed by proton beams of 3 and 7 MeV energies, produced by a linear accelerator, in a fluence range from 1011 to 1015 protons/cm2. The visible photoluminescence spectra of radiation-induced F2 and F3+ laser active color centers, which possess almost overlapping absorption bands at about 450 nm, were measured under laser pumping at 458 nm. On the basis of simulations of the linear energy transfer with proton penetration depth in LiF, it was possible to obtain the behavior of the measured integrated photoluminescence intensity of proton irradiated LiF films as a function of the deposited dose. The photoluminescence signal is linearly dependent on the deposited dose in the interval from 103 to about 106 Gy, independently from the used proton energies. This behavior is very encouraging for the development of advanced solid state radiation detectors based on optically transparent LiF thin films for proton beam diagnostics and two-dimensional dose mapping.

  20. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2012-01-01

    In 2011, world lithium consumption was estimated to have been about 25 kt (25,000 st) of lithium contained in minerals and compounds, a 10-percent increase from 2010. U.S. consumption was estimated to have been about 2 kt (2,200 st) of contained lithium, a 100-percent increase from 2010. The United States was estimated to be the fourth-ranked consumer of lithium and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. One company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic brine resources near Silver Peak, NV.

  1. Lithium

    USGS Publications Warehouse

    Ober, J.A.

    2006-01-01

    In 2005, lithium consumption in the United States was at 2.5 kt of contained lithium, nearly 32% more than the estimate for 2004. World consumption was 14.1 kt of lithium contained in minerals and compounds in 2003. Exports from the US increased slightly compared with 2004. Due to strong demand for lithium compounds in 2005, both lithium carbonate plants in Chile were operating at or near capacity.

  2. Radiation Induced Optical Absorption of Cubic Lead Fluoride Crystals and the Effect of Annealing

    NASA Astrophysics Data System (ADS)

    Ren, Guo-Hao; Chen, Xiao-Feng; Li, Huan-Ying; Wu, Yun-Tao; Shi, Hong-Sheng; Qin, Lai-Shun

    2014-08-01

    Transparent and colorless lead fluoride crystals with sizes of 20 × 20 × 20 (mm3) are irradiated with several doses of γ-rays from a 60 Co source. Their transmittance spectra before and after irradiation are measured, and a new parameter ΔT = Tb - Ta is defined to evaluate the irradiation damage. Three optical absorption bands peaking at 270 nm, 370 nm and 500 nm are found in the plots of ΔT versus wavelength, and their intensities increase with the irradiation dose. These optical absorption bands, except the one at 270 nm, can recover spontaneously with time. Thermal annealing treatment can enhance this recovery of the transmittance, while the optimum annealing temperature for different samples depends on the irradiation dose.

  3. Elastic properties of poly(vinyldene fluoride) (PVDF) crystals: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Pei, Yong; Zeng, Xiao Cheng

    2011-05-01

    We computed structural and elastic properties of totally nine phases of poly(vinyldene fluoride) (PVDF) crystals using the density-functional theory (DFT) method with and without inclusion of the dispersion corrections. In addition to the four known crystalline forms, mechanic properties of five theoretically predicted crystalline forms of PVDF are also investigated. The all-trans form Ip exhibits the largest cohesive energy, bulk, and Young's modulus among the nine crystalline forms. The DFT calculations suggest that the δ crystalline forms (IIIau, IIIpu, IIIpd, and IIIad) possess poor chain rigidity among the nine PVDF crystalline forms. In contrast, a change of relative orientation of PVDF chains does not lead to significant change in cohesive energy and mechanic properties. A comparison of the cohesive energies of nine crystalline forms of PVDF suggests that the theoretically proposed crystalline forms of PVDF are quite stable.

  4. Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

    SciTech Connect

    Thiede, Christian Schmidt, Anke B.; Donath, Markus

    2015-08-15

    Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination, temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters.

  5. Properties of Ru-doped near-stoichiometric lithium niobate crystals produced by vapor transport equilibration

    NASA Astrophysics Data System (ADS)

    Chiang, Chang-Hung; Chen, Jyh-Chen; Huang, Tzu-Ming; Hu, Chieh

    2008-05-01

    Ruthenium (Ru)-doped near-stoichiometric lithium niobate crystals (Ru:SLN) were prepared by the vapor transport equilibration (VTE) technique from Ru-doped congruent lithium niobate (CLN) grown using the Czochralski method. Increasing the duration time of the VTE treatment caused the ratio of [Li]/[Nb] in the crystal to increase, which in turn caused the absorption edges to shift to violet. The absorption coefficient in the UV/VIS absorption spectra at 530 nm decreased because of the change in the valence of the Ru ions cause by the VTE treatment. The OH - absorption spectra showed that the broad band located at 3482 cm -1 gradually decreased while another band located at 3466 cm -1 gradually increased and the shape became sharper as the VTE treatment time increased. When the VTE treatment time reached 200 h, Ru-doped near-stoichiometric lithium niobate crystals were obtained. Two-beam coupling examination with a 532 nm laser showed that the Ru-doped near-stoichiometric lithium niobate crystals had a larger exponential gain coefficient, lower diffraction efficiency, faster response time, and higher sensitivity than did the Ru-doped CLN crystals.

  6. Growth, Structural And Optical Studies On Bis L-alanine Lithium Chloride (BLALC) Single Crystal

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Bis L-alanine Lithium Chloride (BLALC) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 15 x 9 x 4 mm3 have been obtained in 28 days. The grown crystals were colourless and transparent. Single crystal X-ray diffraction (XRD) study showed that BLALC belongs to orthorhombic system with a non-centro-symmetric space group P212121. The crystallinity of BLALC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. The functional groups of the grown crystals have been identified by FTIR studies. UV-visible transmittance spectrum was recorded to study the optical transparency of BLALC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique.

  7. Lithium

    USGS Publications Warehouse

    Ober, J.

    1998-01-01

    The lithium industry can be divided into two sectors: ore concentrate producers and chemical producers. Ore concentrate producers mine lithium minerals. They beneficiate the ores to produce material for use in ceramics and glass manufacturing.

  8. Non-Isothermal Calorimetric Studies of the Crystallization of Lithium Disilicate Glass

    NASA Technical Reports Server (NTRS)

    Ray, C. S.; Day, D. E.; Huang, W.; Narayan, K. Lakshmi; Cull, T. S.; Kelton, K. F.

    1996-01-01

    The influence of preannealing treatments on the polymorphic crystallization of lithium disilicate glasses is examined. As expected, glasses heated at different rates through the temperature range where there is significant nucleation develop widely different numbers of nuclei. This can dramatically influence the stability and transformation characteristics of the annealed glass. Non-isothermal differential scanning calorimetry (DSC) and differential thermal analysis (DTA) measurements are demonstrated to be useful to probe the nucleation behavior. The first systematic investigations of particle size effects on the non-isothermal transformation behavior are presented and discussed. Based on DTA and microscopy experiments, we show that small particles of lithium disilicate glasses crystallize primarily by surface crystallization. The relative importance of surface versus volume crystallization is examined by varying particle size, by introducing nucleating agents and by exposing glasses to atmospheres of different water content. These data are analyzed quantitatively using a numerical model developed in a second paper following in this volume.

  9. Development of a fast radiation detector based on barium fluoride scintillation crystal

    SciTech Connect

    Han, Hetong; Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Zhang, Kan; Li, Gang; Guan, Xingyin

    2013-07-15

    Barium fluoride (BaF{sub 2}) is an inorganic scintillation material used for the detection of X/gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF{sub 2} has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF{sub 2} has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF{sub 2} scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands.

  10. Study on effect of poly (ethylene oxide) addition and in-situ porosity generation on poly (vinylidene fluoride)-glass ceramic composite membranes for lithium polymer batteries

    NASA Astrophysics Data System (ADS)

    Shubha, Nageswaran; Prasanth, Raghavan; Hng, Huey Hoon; Srinivasan, Madhavi

    2014-12-01

    The effect of blending polyethylene oxide with poly (vinylidene fluoride)-lithium aluminum germanium phosphate (LAGP) composite and in-situ porosity generation on the electrochemical performance of polymer electrolytes based on non-woven fibrous mats is studied. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, multilayered, three dimensional network structure of ultrafine fibers. The electrospun membranes are subjected to a preferential polymer dissolution process to prepare a highly porous structure. The membranes show high surface roughness with uniformly sized and distributed pores on the fibers. The membranes with good mechanical strength, thermal stability and high porosity exhibit high swelling when activated with liquid electrolyte. The prepared composite polymer electrolytes show high ionic conductivity. The addition of the glass ceramic improves the mechanical and thermal stability, while blending and in-situ porosity generation improves the ionic conductivity, charge-discharge performance, cycling stability, interface properties and compatibility with lithium electrode.

  11. Method of forming single crystals of beta silicon carbide using liquid lithium as a solvent

    DOEpatents

    Lundberg, Lynn B.

    1982-01-01

    A method of growing single crystals of beta SiC from solution using molten lithium as a solvent for polycrystalline SiC feed material. Reasonable growth rates are accomplished at temperatures in the range of about 1330.degree. C. to about 1500.degree. C.

  12. Influence of sodium fluoride (NaF) on the crystallization and spectral properties of L-tyrosine

    NASA Astrophysics Data System (ADS)

    Thenmozhi, M.; Suguna, K.; Sekar, C.

    2011-12-01

    L-Tyrosine (C 9H 11NO 3) is an essential amino acid in living organisms. It is also a building unit in protein, takes part in bio-synthesis of hormones, neurotransmitters, pigments and one of the organic chemical constituents of urinary stones. L-Tyrosine has been crystallized in silica gel by double diffusion technique with and without the addition of NaF. The crystals had rosette-like shape. In case of fluoride addition, two types of crystals have formed: rosette like crystallites, at the gel-solution interface and reticulate type crystallites beneath the interface. XRD results confirmed that both the products are of L-tyrosine with identical crystal structures. Crystal structure, morphology, thermal and spectral properties are analyzed using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR) and UV-vis transmittance studies. The TG-DTA results suggest that the thermal stability of L-tyrosine has markedly improved due to fluoride doping. Optical band gap energy of NaF grown L-tyrosine crystallite is estimated as 4.28 eV. Second harmonic generation efficiency test indicates that L-tyrosine crystals can be used for application in nonlinear optical devices.

  13. [Lithium].

    PubMed

    Sparsa, A; Bonnetblanc, J-M

    2004-03-01

    The mode of action of the cation lithium is not well known. It is at present used as a topical drug in dermatology. Lithium inhibits many enzymes: Na/K ATPase, adenylcyclase, enzymes of the prostaglandines E1 synthesis, inositol-1-phosphatase. It is active on neutrophils et T lymphocytes, explaining in part its anti-inflammatory activity. It has a dose-dependent action on levures. It has possibly a direct inhibitory activity on DNA synthesis of herpes viruses. Lithium has a good local safety. Percutaneous penetration is weak and plasma concentrations are very much lower than that observed after oral intake. Lithium has been studied in seborrhoeic dermatitis. Its efficacy was primarily observed in psychotic patients. An assay with oral lithium did not confirmed the first observations. Topical lithium was found more efficient. Topical lithium succinate associated with zinc sulfate and lithium gluconate had a greater efficacy than placebo. Comparison with topical ketoconazole showed a non inferiority of lithium gluconate. Oral lithium also showed a reduction of symptoms' duration of herpes simplex. Cutaneous side-effects of oral lithium are frequent and numerous. Some of them may be explained by a lithium pharmacological cell activity (such as psoriasis). Teratogenicity is observed in mice and rats. Drug interactions are not expected after topical application. Irritants side effects are mainly observed after topical application; they are moderate and transitory. Lithium gluconate treatment of seborrhoeic dermatitis is a bid application during at least 8 weeks. It may be used in renal insufficiency. It is not recommended in the first trimester of pregnancy.

  14. Photonic crystal structures in ion-sliced lithium niobate thin films.

    PubMed

    Sulser, Frederik; Poberaj, Gorazd; Koechlin, Manuel; Günter, Peter

    2009-10-26

    We report on the first realization of photonic crystal structures in 600-nm thick ion-sliced, single-crystalline lithium niobate thin films bonded on a lithium niobate substrate using adhesive polymer benzocyclobutene (BCB). Focused ion beam (FIB) milling is used for fast prototyping of photonic crystal structures with regular cylindrical holes. Unwanted redeposition effects leading to conically shaped holes in lithium niobate are minimized due to the soft BCB layer underneath. A high refractive index contrast of 0.65 between the lithium niobate thin film and the BCB underlayer enables strong light confinement in the vertical direction. For TE polarized light a triangular photonic crystal lattice of air holes with a diameter of 240 nm and a separation of 500 nm has a photonic bandgap in the wavelength range from 1390 to 1500 nm. Experimentally measured transmission spectra show a spectral power dip for the GK direction of the reci ocal lattice with an extinction ratio of up to 15 dB. This is in good agreement with numerical simulations based on the three-dimensional plane wave expansion (PWE) and the finite-difference time-domain (FDTD) method.

  15. Photonic crystal slab fabricated on the platform of lithium niobate-on-insulator.

    PubMed

    Cai, Lutong; Han, Huangpu; Zhang, Shaomei; Hu, Hui; Wang, Keming

    2014-04-01

    We report on a photonic crystal slab patterned on a 690 nm thick LiNbO3 thin film bonded to SiO2 on lithium niobate substrate. The transmission spectrum is measured and a broad and clear photonic bandgap ranging from 1335 to 1535 nm with a maximum extinction ratio of more than 20 dB is observed. The bandgap is simulated by plane wave expansion and 3D finite-difference time-domain methods. Such a deep and broad bandgap structure can be used to form high-performance photonic devices and circuits on the platform of lithium niobate-on-insulator.

  16. Shape of isolated domains in lithium tantalate single crystals at elevated temperatures

    SciTech Connect

    Shur, V. Ya. Akhmatkhanov, A. R.; Baturin, I. S.; Chezganov, D. S.; Lobov, A. I.; Smirnov, M. M.

    2013-12-09

    The shape of isolated domains has been investigated in congruent lithium tantalate (CLT) single crystals at elevated temperatures and analyzed in terms of kinetic approach. The obtained temperature dependence of the growing domain shape in CLT including circular shape at temperatures above 190 °C has been attributed to increase of relative input of isotropic ionic conductivity. The observed nonstop wall motion and independent domain growth after merging in CLT as opposed to stoichiometric lithium tantalate have been attributed to difference in wall orientation. The computer simulation has confirmed applicability of the kinetic approach to the domain shape explanation.

  17. Crystal reduction in TA-23 glass-to-metal seals. [For lithium ambient-temperature batteries

    SciTech Connect

    Kovacic, L.; Watkins, R.D.

    1987-05-01

    TA-23 glass is used in the fabrication of headers for lithium ambient-temperature batteries. The glass was observed to crystallize during processing at the sealing temperature originally specified. Thermal expansion characteristics of the crystal phase suggested potential problems from residual stresses in the glass seal. Two methods are presented to reduce or eliminate the crystallization: improvement of the glass preform surface finish and lower temperature sealing. Both methods were successful in reducing crystallization in the glass during sealing. Sealed headers were characterized for seal integrity by acoustic emission pressure testing and pin-pull testing. Seals without the crystals were found to be stronger than those with the crystals present. Details of the process development and mechanical testing are presented.

  18. Change in the structural imperfection of lithium niobate crystals doped with zinc

    SciTech Connect

    Litvinova, V. A. Litvinova, M. N.

    2015-01-15

    The changes in the degree of structural imperfection of lithium niobate (LiNbO{sub 3}) single crystals with an increase in the Li content and doping with zinc (to 1 wt %) have been investigated by the nonlinear optics methods and Raman spectroscopy. The conversion of broadband IR radiation in LiNbO{sub 3} crystals under noncritical (90°) phase-matching condition with vector interactions implemented is investigated. It is shown that the conversion efficiency, spectral width, and the position of maximum in the converted radiation spectrum depend on the ratio R = Li/Nb in LiNbO{sub 3} crystal and the impurity concentration.

  19. Effects of fluorine on crystallization, structure and performances of lithium aluminosilcate glass ceramic

    SciTech Connect

    Guo Xingzhong . E-mail: gxzh_zju@163.com; Yang Hui

    2006-02-02

    The effects of fluorine on the nucleation, crystallization, structure and performances of low-expansion lithium aluminosilcate glass ceramic are investigated by the differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and other measuring technologies. The introduction of fluorine promotes the nucleation and crystallization of LAS glass, lowers the crystallizing temperature, allows a direct formation of {beta}-spodumene without the transformation from {beta}-quartz into {beta}-spodumene and as a result, refines the microstructure and improves the physical and mechanical properties of the glass ceramics.

  20. The crystal structure of phase IV of poly(vinylidene fluoride)

    NASA Astrophysics Data System (ADS)

    Bachmann, M.; Gordon, W. L.; Weinhold, S.; Lando, J. B.

    1980-10-01

    The crystal structure of phase IV (polar α or δ phase) poly(vinylidene fluoride) was studied by x-ray diffraction. Oriented phase IV was obtained by orienting phase II (α phase) and then corona poling at approximately 2 MV/cm. The resulting material is a mixture of phases I, II, and IV. Infrared spectra indicate that phase IV has the same chain conformation (TGTG') as phase II. The reflections of phase IV can be indexed to an orthorhombic unit cell with lattice constants similar to the phase II lattice constants, a=0.496 nm, b=0.964 nm, and c (chain axis)=0.462 nm. There are two chains in this unit cell. The two chains pack with the chain dipole moments parallel. Three different ways of packing the chains were investigated: both chains up, one up and one down, and a statistical up-down packing. It was found that to within a 97% confidence level, the chains pack with a statistical up-down packing.

  1. Comment on the paper: "Crystal growth and spectroscopic characterization of Aloevera amino acid added lithium sulfate monohydrate: a non-linear optical crystal".

    PubMed

    Srinivasan, Bikshandarkoil R

    2015-01-01

    The title paper (Manimekalai et al., 2014) reports a slow evaporation solution growth of a so called 'Aloevera amino acid added lithium sulfate monohydrate' (AALSMH) crystal. In this communication, many points of criticism, concerning the crystal growth, NMR spectrum and X-ray powder pattern of this so called AALSMH nonlinear optical crystal are highlighted.

  2. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-10-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g-1 at 25 mA g-1 up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g-1 at 250 mA g-1 up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g-1 was maintained at 25 mA g-1 after 115 cycles in the potential range of 2.9-0.5 V.

  3. Growth and characterization of new semiorganic nonlinear optical and piezoelectric lithium sulfate monohydrate oxalate single crystals

    SciTech Connect

    Yadav, Harsh; Sinha, Nidhi; Kumar, Binay

    2015-04-15

    Highlights: • A new semiorganic single crystal of LSO grown by slow evaporation technique. • Morphological studies of the LSO crystal deduced by BFDH law. • In the UV–vis spectrum wide transparent region and large band gap were found. • SHG is equal to KDP crystal and d{sub 33} was found to be equal to 6pC/N. • Grown crystal belongs to softer category. - Abstract: New semiorganic crystal of lithium sulfate monohydrate oxalate (LSO) for nonlinear application was synthesized by controlled slow evaporation method. The growth rate of various planes of the grown crystal was estimated by morphological study. Single crystal XRD analysis confirmed that the crystal belongs to triclinic lattice with space group P1. High transparency (∼95%) with large band gap (4.57 eV) was analyzed by UV–vis studies. FTIR and Raman spectroscopy were used to identify various functional groups present in the LSO crystal. SHG efficiency was found to be equal to the KDP crystal. Thermal stability (up to 117.54 °C) and melting point (242 °C) of the crystal were studied by TG-DTA. In dielectric measurements, the value of dielectric constant decreases with increase in frequency. Hardness studies confirmed soft nature of crystals. The piezoelectric coefficient was found to be 6pC/N along [0 0 1].

  4. Zirconium dioxide nanofilled poly(vinylidene fluoride-hexafluoropropylene) complexed with lithium trifluoromethanesulfonate as composite polymer electrolyte for electrochromic devices

    SciTech Connect

    Puguan, John Marc C.; Chinnappan, Amutha; Kostjuk, Sergei V.; Kim, Hern

    2015-09-15

    Highlights: • Successful synthesis of electrolyte by blending PVdF-HFP, ZrO{sub 2} and LiCF{sub 3}SO{sub 3}. • ZrO{sub 2} increased electrolyte conductivity by two orders of magnitude. • ZrO{sub 2} doubled bulk mechanical strength of electrolyte in terms of Young’s modulus. • Electrolytes gave a optimum optical transmittance of 52.6%. - Abstract: Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) polymer electrolyte containing zirconium dioxide nanocrystals (ZrO{sub 2}-NC) and lithium trifluoromethanesulfonate (LiCF{sub 3}SO{sub 3}) has been synthesized using the conventional solution casting method. The addition of ZrO2-NC into the polymeric substrate gave remarkable properties in terms of the electrolyte’s ionic conductivity as well as its bulk mechanical strength. The enhanced amorphicity of the polymeric substrate due to ZrO{sub 2} and the nanofiller’s high dielectric constant make an excellent combination to increase the ionic conductivity (above 10{sup −4} S cm{sup −1}). Increasing the nanofiller content raises the ionic conductivity of the electrolyte by two orders of magnitude of which the optimum is 2.65 × 10{sup −4} S cm{sup −1} at 13.04 wt% ZrO{sub 2}-NC loading. Also, the Young’s modulus, an indicator of electrolyte’s mechanical stability, dramatically increased to 207 MPa upon loading 13.04 wt% ZrO{sub 2}-NC. Using UV–vis spectroscopy, the electrolytes with 13.04% ZrO{sub 2}-NC scanned from 200–800 nm wavelengths exhibited a maximum optical transmittance of 52.6% at 10 μm film thickness. The enhanced conductivity, high mechanical strength and reasonable optical transmittance shown by our composite polymer electrolyte make an excellent electrolyte for future energy saving smart windows such as electrochromic devices.

  5. Raman spectroscopy study of compositional inhomogeneity in lithium tantalate crystals

    NASA Astrophysics Data System (ADS)

    Kostritskii, S. M.; Aillerie, M.; Bourson, P.; Kip, D.

    2009-04-01

    Raman spectra of LiTaO3 single crystals with various stoichiometries were measured to investigate the compositional uniformity of these crystals. Raman spectra mapping demonstrates a spatial variation of the widths of the phonon bands for stoichiometric, congruent, and quasi-congruent samples. A significant radial compositional inhomogeneity is found to be a common feature of commercially available wafers having a near-congruent crystal composition (i.e., x c ={[Li2O]/([Li2O]+[Ta2O5])}×100%=47.85-48.50%) grown by the single-crucible Czochralski method. A maximum value of the composition gradient ∇ x c for a radial inhomogeneity of 0.163 and 0.036%/cm is measured for thin wafers diced from so-called congruent (vendors’ value of x c =48.50%) and quasi-congruent ( x c =47.88%) crystals, respectively. In crystals grown from highly Li-rich melts (starting composition 54.5 mol% Li2O), a drastic spatial dependence of Raman bandwidths, indicating a significant gradual compositional inhomogeneity throughout the crystal, is found, which is due to a change of the melt composition during crystal growth. In contrast, the Raman bandwidths of near-stoichiometric crystals fabricated by a vapor transport equilibrium (VTE) technique are found to be constant, i.e. these crystals are practically compositionally uniform. This conclusion has been confirmed by mapping the photoluminescence intensity, evidencing ∇ x c ≤0.006%/cm in near-stoichiometric VTE-treated crystals.

  6. Ultrathin two-dimensional atomic crystals as stable interfacial layer for improvement of lithium metal anode.

    PubMed

    Yan, Kai; Lee, Hyun-Wook; Gao, Teng; Zheng, Guangyuan; Yao, Hongbin; Wang, Haotian; Lu, Zhenda; Zhou, Yu; Liang, Zheng; Liu, Zhongfan; Chu, Steven; Cui, Yi

    2014-10-01

    Stable cycling of lithium metal anode is challenging due to the dendritic lithium formation and high chemical reactivity of lithium with electrolyte and nearly all the materials. Here, we demonstrate a promising novel electrode design by growing two-dimensional (2D) atomic crystal layers including hexagonal boron nitride (h-BN) and graphene directly on Cu metal current collectors. Lithium ions were able to penetrate through the point and line defects of the 2D layers during the electrochemical deposition, leading to sandwiched lithium metal between ultrathin 2D layers and Cu. The 2D layers afford an excellent interfacial protection of Li metal due to their remarkable chemical stability as well as mechanical strength and flexibility, resulting from the strong intralayer bonds and ultrathin thickness. Smooth Li metal deposition without dendritic and mossy Li formation was realized. We showed stable cycling over 50 cycles with Coulombic efficiency ∼97% in organic carbonate electrolyte with current density and areal capacity up to the practical value of 2.0 mA/cm(2)and 5.0 mAh/cm(2), respectively, which is a significant improvement over the unprotected electrodes in the same electrolyte.

  7. A computer study and photoelectric property analysis of potassium-doped lithium niobate single crystals.

    PubMed

    Wang, Wei; Wang, Rui; Zhang, Wen; Xing, Lili; Xu, Yanling; Wu, Xiaohong

    2013-09-14

    First-principles theory was used to design a potassium-doped lithium niobate single crystal. The structural, electronic, optical and ferroelectric properties of the potassium-doped LiNbO3 single crystal model have been investigated using a generalized gradient approximation within density functional theory. It was found that substitution with potassium drastically changed the optical and electronic nature of the crystal and that the band gap slightly decreases. A series of LiNbO3 single crystals doped with x mol% K (x = 0, 3, 6, 9, 12 mol%) were successfully grown using the Czochralski method. The crystals were characterized using powder X-ray diffraction, UV-vis-infrared absorption spectroscopy and a ferroelectric property test. The experimental test results were consistent with the calculated predictions.

  8. Induced Li-site vacancies and non-linear optical behavior of doped lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Xue, D.; Betzler, K.; Hesse, H.

    2001-04-01

    Second-order non-linear optical (NLO) properties of doped lithium niobate (LN) crystals (abbreviated as M:LN, where M=Mg 2+,Zn 2+, and In 3+, respectively) have been quantitatively studied from the chemical bond viewpoint. Our results show that the second-order NLO response of doped LN crystals decreases remarkably with increasing dopant concentration in the crystal. The approximately linear composition-property correlation in these doped LN crystals is quantitatively expressed in the current work. A comparison of the different influences of Mg, Zn and In dopants, respectively, shows that these dopants affect the NLO properties of LN crystals mainly via the number of Li-site vacancies induced.

  9. Synthesis, structure, crystal growth and characterization of a novel semiorganic nonlinear optical L-proline lithium bromide monohydrate single crystal

    NASA Astrophysics Data System (ADS)

    Sathiskumar, S.; Balakrishnan, T.; Ramamurthi, K.; Thamotharan, S.

    2015-03-01

    L-Proline lithium bromide monohydrate (LPLBM), a promising semiorganic nonlinear optical material, was synthesized and single crystals of LPLBM were grown from solution by slow evaporation technique. Single crystal X-ray structure solution reveals that the grown crystal belongs to monoclinic system with space group P21. Presence of various functional groups was identified by FT-IR and FT-Raman spectral analyses. UV-Vis-NIR spectroscopic study shows that the LPLBM crystal possesses 90% of transmittance in the range of 250-1100 nm. Vickers microhardness values, the dielectric constant and dielectric loss of the LPLBM crystal were reported. Elemental analysis by energy dispersive X-ray analysis shows the presence of carbon, nitrogen, oxygen and bromine. The surface morphology of the crystal was investigated using scanning electron microscopic study. The thermal stability of the LPLBM crystal was studied from TGA and DSC analysis. Second harmonic generation efficiency of the LPLBM crystal measured by Kurtz and Perry powder technique using Nd:YAG laser is about 0.3 times that of urea.

  10. Preparation of room temperature terahertz detector with lithium tantalate crystal and thin film

    SciTech Connect

    Wang, Jun Gou, Jun; Li, Weizhi

    2014-02-15

    Research on room temperature terahertz (THz) detector is essential for promoting the application of THz science and technology. Both lithium tantalate crystal (LiTaO{sub 3}) and lithium tantalate thin film were used to fabricate the THz detector in this paper. Polishing process were used to reduce the thickness of LiTaO{sub 3} crystal slice by chemical mechanical polishing techniques and an improved sol-gel process was used to obtain high concentration LiTaO{sub 3} precursor solution to fabricate LiTaO{sub 3} thin film. Three dimension models of two THz detectors were set up and the temperature increasing map of two devices were simulated using finite element method. The lowest noise equivalent power value for terahertz detector using pyroelectric material reaches 6.8 × 10{sup −9} W at 30 Hz operating frequency, which is suitable for THz imaging application.

  11. Growth and characterization of lithium yttrium borate single crystals

    SciTech Connect

    Singh, A. K.; Singh, S. G.; Tyagi, M.; Desai, D. G.; Sen, Shashwati

    2014-04-24

    Single crystals of 0.1% Ce doped Li{sub 6}Y(BO{sub 3}){sub 3} have been grown using the Czochralski technique. The photoluminescence study of these crystals shows a broad emission at ∼ 420 nm corresponding to Ce{sub 3+} emission from 5d→4f energy levels. The decay profile of this emission shows a fast response of ∼ 28 ns which is highly desirable for detector applications.

  12. Interdomain region in single-crystal lithium niobate bimorph actuators produced by light annealing

    SciTech Connect

    Kubasov, I. V. Timshina, M. S.; Kiselev, D. A.; Malinkovich, M. D.; Bykov, A. S.; Parkhomenko, Yu. N.

    2015-09-15

    The interdomain region of a bidomain strucrture formed in 127°-cut lithium niobate single crystals using light annealing has been studied by optical and scanning probe microscopies. A periodic subdomain structure on the 180° macrodomain wall is visualized by piezoresponse force microscopy. The piezoresponse signal (polarization) is shown to be a power-law function of the domain width with an exponent n = 0.53.

  13. Theoretical study of the anisotropic diffraction of light waves by acoustic waves in lithium niobate crystals.

    PubMed

    Rouvaen, J M; Waxin, G; Gazalet, M G; Bridoux, E

    1990-03-20

    The anisotropic diffraction of light by high frequency longitudinal ultrasonic waves in the tangential phase matching configuration may present some definite advantages over the same interaction using transverse acoustic waves. A systematic search for favorable crystal cuts in lithium niobate was worked out. The main results of this study are reported here; they enable the choice of the best configuration for a given operating center frequency.

  14. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  15. Pyroelectric field assisted ion migration induced by ultraviolet laser irradiation and its impact on ferroelectric domain inversion in lithium niobate crystals

    SciTech Connect

    Ying, C. Y. J.; Mailis, S.; Daniell, G. J.; Steigerwald, H.; Soergel, E.

    2013-08-28

    The impact of UV laser irradiation on the distribution of lithium ions in ferroelectric lithium niobate single crystals has been numerically modelled. Strongly absorbed UV radiation at wavelengths of 244–305 nm produces steep temperature gradients which cause lithium ions to migrate and result in a local variation of the lithium concentration. In addition to the diffusion, here the pyroelectric effect is also taken into account which predicts a complex distribution of lithium concentration along the c-axis of the crystal: two separated lithium deficient regions on the surface and in depth. The modelling on the local lithium concentration and the subsequent variation of the coercive field are used to explain experimental results on the domain inversion of such UV treated lithium niobate crystals.

  16. Low-voltage nanodomain writing in He-implanted lithium niobate crystals

    SciTech Connect

    Lilienblum, M.; Hoffmann, A.; Soergel, E.; Ofan, A.; Gaathon, O.; Osgood, R. M. Jr.; Vanamurthy, L.; Bakhru, S.; Bakhru, H.

    2010-02-22

    A scanning force microscope tip is used to write ferroelectric domains in He-implanted single-crystal lithium niobate and subsequently probe them by piezoresponse force microscopy. Investigation of cross-sections of the samples showed that the buried implanted layer, approx1 mum below the surface, is nonferroelectric and can thus act as a barrier to domain growth. This barrier enabled stable surface domains of <1 mum size to be written in 500 mum thick crystal substrates with voltage pulses of only 10 V applied to the tip.

  17. Inhibition of microbial growth, study of solution stability, growth and characterization of potassium fluoride mixed ?-arginine phosphate single crystals

    NASA Astrophysics Data System (ADS)

    Haja Hameed, A. S.; Ravi, G.; Ramasamy, P.

    2001-07-01

    In order to alleviate the major problem of microbial growth and colouration in L-arginine phosphate (LAP), the use of potassium fluoride (KF), a new additive having higher dipole moment, has been proposed. The stabilities of the pure and KF mixed LAP solution at different temperatures have been determined. Pure and KF mixed LAP crystals were grown by the temperature lowering technique. The presence of potassium in the crystal was identified by inductively coupled plasma analysis (ICP). The lattice parameters for the grown crystals were determined from X-ray powder diffraction. The molecular vibration and thermal behaviour of KF mixed LAP were found from Fourier transform infrared (FTIR) spectroscopy and thermal analysis (DTA &TGA) respectively.

  18. Lithium

    MedlinePlus

    ... depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Lithium is in a class of medications called antimanic agents. It works by decreasing abnormal activity in the brain.

  19. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    NASA Astrophysics Data System (ADS)

    Radzhabov, E.

    2002-06-01

    Defects in Ce 3+- and Eu 2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF 2:Eu 2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce 3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF 2:Ce 3+ and SrF 2:Ce 3+ crystals. Creation of Ce 2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce 3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce 2+ or Eu + ions.

  20. Decomposition of the fluoroethylene carbonate additive and the glue effect of lithium fluoride products for the solid electrolyte interphase: an ab initio study.

    PubMed

    Okuno, Yukihiro; Ushirogata, Keisuke; Sodeyama, Keitaro; Tateyama, Yoshitaka

    2016-03-28

    Additives in the electrolyte solution of lithium-ion batteries (LIBs) have a large impact on the performance of the solid electrolyte interphase (SEI) that forms on the anode and is a key to the stability and durability of LIBs. We theoretically investigated effects of fluoroethylene carbonate (FEC), a representative additive, that has recently attracted considerable attention for the enhancement of cycling stability of silicon electrodes and the improvement of reversibility of sodium-ion batteries. First, we intensively examined the reductive decompositions by ring-opening, hydrogen fluoride (HF) elimination to form a vinylene carbonate (VC) additive and intermolecular chemical reactions of FEC in the ethylene carbonate (EC) electrolyte, by using density functional theory (DFT) based molecular dynamics and the blue-moon ensemble technique for the free energy profile. The results show that the most plausible product of the FEC reductive decomposition is lithium fluoride (LiF), and that the reactivity of FEC to anion radicals is found to be inert compared to the VC additive. We also investigated the effects of the generated LiF on the SEI by using two model systems; (1) LiF molecules distributed in a model aggregate of organic SEI film components (SFCs) and (2) a LiF aggregate interfaced with the SFC aggregate. DFT calculations of the former system show that F atoms form strong bindings with the Li atoms of multiple organic SFC molecules and play as a joint connecting them. In the latter interface system, the LiF aggregate adsorbs the organic SFCs through the F-Li bindings. These results suggest that LiF moieties play the role of glue in the organic SFC within the SEI film. We also examined the interface structure between a LiF aggregate and a lithiated silicon anode, and found that they are strongly bound. This strong binding is likely to be related to the effectiveness of the FEC additive in the electrolyte for the silicon anode.

  1. Decomposition of the fluoroethylene carbonate additive and the glue effect of lithium fluoride products for the solid electrolyte interphase: an ab initio study.

    PubMed

    Okuno, Yukihiro; Ushirogata, Keisuke; Sodeyama, Keitaro; Tateyama, Yoshitaka

    2016-03-28

    Additives in the electrolyte solution of lithium-ion batteries (LIBs) have a large impact on the performance of the solid electrolyte interphase (SEI) that forms on the anode and is a key to the stability and durability of LIBs. We theoretically investigated effects of fluoroethylene carbonate (FEC), a representative additive, that has recently attracted considerable attention for the enhancement of cycling stability of silicon electrodes and the improvement of reversibility of sodium-ion batteries. First, we intensively examined the reductive decompositions by ring-opening, hydrogen fluoride (HF) elimination to form a vinylene carbonate (VC) additive and intermolecular chemical reactions of FEC in the ethylene carbonate (EC) electrolyte, by using density functional theory (DFT) based molecular dynamics and the blue-moon ensemble technique for the free energy profile. The results show that the most plausible product of the FEC reductive decomposition is lithium fluoride (LiF), and that the reactivity of FEC to anion radicals is found to be inert compared to the VC additive. We also investigated the effects of the generated LiF on the SEI by using two model systems; (1) LiF molecules distributed in a model aggregate of organic SEI film components (SFCs) and (2) a LiF aggregate interfaced with the SFC aggregate. DFT calculations of the former system show that F atoms form strong bindings with the Li atoms of multiple organic SFC molecules and play as a joint connecting them. In the latter interface system, the LiF aggregate adsorbs the organic SFCs through the F-Li bindings. These results suggest that LiF moieties play the role of glue in the organic SFC within the SEI film. We also examined the interface structure between a LiF aggregate and a lithiated silicon anode, and found that they are strongly bound. This strong binding is likely to be related to the effectiveness of the FEC additive in the electrolyte for the silicon anode. PMID:26948716

  2. Growth and properties of Lithium Salicylate single crystals

    SciTech Connect

    Zaitseva, N; Newby, J; Hull, G; Saw, C; Carman, L; Cherepy, N; Payne, S

    2009-02-13

    An attractive feature of {sup 6}Li containing fluorescence materials that determines their potential application in radiation detection is the capture reaction with slow ({approx}< 100 keV) neutrons: {sup 6}Li + n = {sup 4}He + {sup 3}H + 4.8MeV. The use of {sup 6}Li-salicylate (LiSal, LiC{sub 6}H{sub 5}O{sub 3}) for thermal neutron detection was previously studied in liquid and polycrystalline scintillators. The studies showed that both liquid and polycrystalline LiSal scintillators could be utilized in pulse shape discrimination (PSD) techniques that enable separation of neutrons from the background gamma radiation. However, it was found that the efficiency of neutron detection using LiSal in liquid solutions was severely limited by its low solubility in commonly used organic solvents like, for example, toluene or xylene. Better results were obtained with neutron detectors containing the compound in its crystalline form, such as pressed pellets, or microscopic-scale (7-14 micron) crystals dispersed in various media. The expectation drown from these studies was that further improvement of pulse height, PSD, and efficiency characteristics could be reached with larger and more transparent LiSal crystals, growth of which has not been reported so far. In this paper, we present the first results on growth and characterization of relatively large, a cm-scale size, single crystals of LiSal with good optical quality. The crystals were grown both from aqueous and anhydrous (methanol) media, mainly for neutron detection studies. However, the results on growth and structural characterization may be interesting for other fields where LiSal, together with other alkali metal salicylates, is used for biological, medical, and chemical (as catalyst) applications.

  3. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries.

    PubMed

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-12-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g(-1) at 25 mA g(-1) up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g(-1) at 250 mA g(-1) up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g(-1) was maintained at 25 mA g(-1) after 115 cycles in the potential range of 2.9-0.5 V. PMID:26474890

  4. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries.

    PubMed

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-12-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g(-1) at 25 mA g(-1) up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g(-1) at 250 mA g(-1) up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g(-1) was maintained at 25 mA g(-1) after 115 cycles in the potential range of 2.9-0.5 V.

  5. Effects of Nanoporous Anodic Alumina Oxide on the Crystallization and Melting Behavior of Poly(vinylidene fluoride).

    PubMed

    Dai, Xiying; Niu, Jiali; Ren, Zhongjie; Sun, Xiaoli; Yan, Shouke

    2016-02-01

    Poly(vinylidene fluoride) (PVDF) nanotubes were fabricated by melt-wetting into porous anodic aluminum oxide (AAO) templates with two different interfacial properties: one is pristine AAO, and the other is modified by FOTS (AAO-F). Their crystallization and melting behaviors are compared with those of a bulk sample. For the PVDF in AAO-F, the nonisothermal crystallization temperature is slightly lower than that of bulk, and the melting temperature is similar to that of bulk. For the PVDF in pristine AAO, when the pore diameter is 200 nm, the crystallization is induced by two kinds of nucleation: heterogeneous nucleation and interface-induced nucleation. On the contrary, in the AAO template with pore diameter smaller than 200 nm, only interface-induced nucleation occurs. The melting temperature of PVDF crystals in the pristine AAO is much higher than that of bulk which can be attributed to the presence of an interfacial layer of PVDF on the template inner surface. The interaction between PVDF and AAO template produces the interfacial layer. Such an interfacial layer plays an important role in enhancing the melting temperature of PVDF crystals. The higher melting peak is always observed when the PVDF is nonisothermally crystallized in the AAO template irrespective of the thermal erasing temperature suggesting the interfacial layer is very stable on the AAO template surface. If the PVDF nanostructures are released from AAO template, the higher melting peak disappears with the enhancement of thermal erasing temperature.

  6. Structural, optical and dielectric studies of novel non-linear Bisglycine Lithium Nitrate piezoelectric single crystal

    NASA Astrophysics Data System (ADS)

    Dalal, Jyoti; Sinha, Nidhi; Kumar, Binay

    2014-11-01

    The novel non-linear semiorganic Bisglycine Lithium Nitrate (BGLiN) single crystals were grown by slow evaporation technique. The structural analysis revealed that it belongs to non-centrosymmetric orthorhombic structure. The presence of various functional groups in the grown crystal was confirmed by FTIR and Raman analysis. Surface morphology of the grown crystal was studied by scanning electron microscopy. The optical studies show that crystal has good transmittance (more than 80%) in the entire visible region and a wide band gap (5.17 eV). The optical constants such as extinction coefficient (K), the reflectance (R) and refractive index (n) as a function of photon energy were calculated from the optical measurements. With the help of these optical constants the electric susceptibility (χc) and both the real (εr) and imaginary (εi) parts of the dielectric constants were also calculated which are required to develop optoelectronic devices. In photoluminescence studies, a broad emission band centered at 404 nm was found in addition to a small band at 352 nm. A broad transition (from 29 to 33 °C) was observed with low dielectric constant value. A high piezoelectric charge coefficient (d33) of 14 pC/N was measured at room temperature which implies its usefulness for various sensor applications. The second harmonic generation efficiency of crystal was found to be 1.5 times to that of KDP. From thermo gravimetric analysis and differential thermal analysis, thermal stability and melting point (246 °C) were investigated. The dielectric behavior, optical characterization, piezoelectric behavior and the non-linear optical properties of the Bisglycine Lithium Nitrate single crystals were reported for the first time which established the usefulness of these crystals for various piezo- and opto-electronics applications.

  7. Novel electrospun poly(vinylidene fluoride- co-hexafluoropropylene)-in situ SiO 2 composite membrane-based polymer electrolyte for lithium batteries

    NASA Astrophysics Data System (ADS)

    Raghavan, Prasanth; Choi, Jae-Won; Ahn, Jou-Hyeon; Cheruvally, Gouri; Chauhan, Ghanshyam S.; Ahn, Hyo-Jun; Nah, Changwoon

    Composite membranes of poly(vinylidene fluoride- co-hexafluoropropylene) {P(VdF-HFP)} and different composition of silica have been prepared by electrospinning polymer solution containing in situ generated silica. These membranes are made up of fibers of 1-2 μm diameters. These fibers are stacked in layers to produce fully interconnected pores that results in high porosity. Polymer electrolytes were prepared by immobilizing 1 M LiPF 6 in ethylene carbonate (EC)/dimethyl carbonate (DMC) in the membranes. The composite membranes exhibit a high electrolyte uptake of 550-600%. The optimum electrochemical properties have been observed for the polymer electrolyte containing 6% in situ silica to show ionic conductivity of 8.06 mS cm -1 at 20 °C, electrolyte retention ratio of 0.85, anodic stability up to 4.6 V versus Li/Li +, and a good compatibility with lithium metal resulting in low interfacial resistance. A first cycle specific capacity of 170 mAh g -1 was obtained when the polymer electrolyte was evaluated in a Li/lithium iron phosphate (LiFePO 4) cell at 0.1 C-rate at 25 °C, corresponding to 100% utilization of the cathode material. The properties of composite membrane prepared with in situ silica were observed to be comparatively better than the one prepared by direct addition of silica.

  8. Closely packed x-poly(ethylene glycol diacrylate) coated polyetherimide/poly(vinylidene fluoride) fiber separators for lithium ion batteries with enhanced thermostability and improved electrolyte wettability

    NASA Astrophysics Data System (ADS)

    Zhai, Yunyun; Xiao, Ke; Yu, Jianyong; Ding, Bin

    2016-09-01

    The x-polyethylene glycol diacrylate (x-PEGDA) coated polyetherimide/polyvinylidene fluoride (PEI/PVdF) membranes are obtained by the facile combination of dip-coating and free radical polymerization of PEGDA on the electrospun PEI/PVdF fiber membranes. Successful cross-linking of PEGDA increases the average fibers diameter from 553 to 817 nm and reduces the packing density, which not only increases the tensile strength of x-PEGDA coated PEI/PVdF membranes, but also decreases the average pore diameter. Besides, the x-PEGDA coated PEI/PVdF membranes are endowed with good wettability, high electrolyte uptake, high ionic conductivity and improved electrochemical stability window because of the good affinity of PEI and PEGDA with liquid electrolyte. Benefiting from the synergetic effect of PEI and PVdF, the x-PEGDA coated PEI/PVdF membranes exhibit excellent thermal stability and nonflammability, which are beneficial for enhancing the safety of lithium ion batteries. More importantly, the x-PEGDA coated PEI/PVdF membranes based Li/LiFePO4 cell exhibits comparable cycling stability with capacity retention of 95.9% after 70 cycles and better rate capability compared with the Celgard membrane based cell. The results clearly demonstrate that the x-PEGDA coated PEI/PVdF membranes are the promising separator candidate with improved wettability and safety for next-generation lithium ion batteries.

  9. Kagomé lattices as cathode: Effect of particle size and fluoride substitution on electrochemical lithium insertion in sodium- and ammonium Jarosites

    NASA Astrophysics Data System (ADS)

    Sandineni, Prashanth; Yaghoobnejad Asl, Hooman; Choudhury, Amitava

    2016-10-01

    Highly crystalline sodium and ammonium Jarosites, NaFe3(SO4)2(OH)6 and NH4Fe3(SO4)2(OH)6, have been synthesized employing hydrothermal synthesis routes. The structures consist of anionic layers of vertex-sharing FeO6 octahedra and SO4 tetrahedral units with interlayer space occupied by Na and ammonium ions, respectively. The corner-sharing FeO6 octahedral units form six and three rings similar to hexagonal tungsten bronze sheets also known as kagomé lattice. These sodium and ammonium Jarosites are thermally stable up to 400 °C and undergo facile electrochemical lithium insertion through the reduction of Fe3+ to Fe2+. Galvanostatic charge-discharge indicates that up to 2.25 and 2 lithium ions per formula unit can be inserted at an average voltage of 2.49 and 2.26 V to the sodium and the ammonium Jarosites, respectively, under slow discharge rate of C/50. The cycle-life and experimental achievable capacity show strong dependence on particle sizes and synthesis conditions. A small amount of fluoride substitution improves both achievable capacity and average voltage.

  10. Scintillation characterization of thallium-doped lithium iodide crystals

    NASA Astrophysics Data System (ADS)

    Khan, Sajid; Kim, H. J.; Kim, Y. D.

    2015-09-01

    The paper discusses scintillation and luminescence properties of thallium-doped LiI crystals, grown by the Bridgman technique. X-ray induced emission spectrum is obtained between 380 nm and 600 nm, and is attributed to the Tl+ ion. The photoluminescence measurement with the excitation wavelength of 305 nm revealed a similar emission spectrum. Light yield, energy resolution and scintillation decay time profiles were studied under 662 keV (137Cs) γ-ray excitation. A maximum light yield of 14,000±1400 ph/MeV and two exponential decay time components were obtained.

  11. Piezo-optic surfaces of lithium niobate crystals

    SciTech Connect

    Mytsyk, B. G. Dem'yanyshyn, N. M.

    2006-07-15

    A method of construction of the spatial distribution of the piezo-optic effect in crystals is proposed. A particular case of this method is the known technique of construction of indicator surfaces of the piezo-optic effect. The essence of the proposed method consists in determining the difference in the radius vectors of the optical indicatrix perturbed by stress and the free optical indicatrix. It is shown that this difference in the radius vectors is mathematically identical to the law of transformation of the piezo-optic tensor during the rotation of the coordinate system.

  12. Single crystal growth from separated educts and its application to lithium transition-metal oxides

    PubMed Central

    Freund, F.; Williams, S. C.; Johnson, R. D.; Coldea, R.; Gegenwart, P.; Jesche, A.

    2016-01-01

    Thorough mixing of the starting materials is the first step of a crystal growth procedure. This holds true for almost any standard technique, whereas the intentional separation of educts is considered to be restricted to a very limited number of cases. Here we show that single crystals of α-Li2IrO3 can be grown from separated educts in an open crucible in air. Elemental lithium and iridium are oxidized and transported over a distance of typically one centimeter. In contrast to classical vapor transport, the process is essentially isothermal and a temperature gradient of minor importance. Single crystals grow from an exposed condensation point placed in between the educts. The method has also been applied to the growth of Li2RuO3, Li2PtO3 and β-Li2IrO3. A successful use of this simple and low cost technique for various other materials is anticipated. PMID:27748402

  13. Single crystal growth from separated educts and its application to lithium transition-metal oxides

    NASA Astrophysics Data System (ADS)

    Freund, F.; Williams, S. C.; Johnson, R. D.; Coldea, R.; Gegenwart, P.; Jesche, A.

    2016-10-01

    Thorough mixing of the starting materials is the first step of a crystal growth procedure. This holds true for almost any standard technique, whereas the intentional separation of educts is considered to be restricted to a very limited number of cases. Here we show that single crystals of α-Li2IrO3 can be grown from separated educts in an open crucible in air. Elemental lithium and iridium are oxidized and transported over a distance of typically one centimeter. In contrast to classical vapor transport, the process is essentially isothermal and a temperature gradient of minor importance. Single crystals grow from an exposed condensation point placed in between the educts. The method has also been applied to the growth of Li2RuO3, Li2PtO3 and β-Li2IrO3. A successful use of this simple and low cost technique for various other materials is anticipated.

  14. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    SciTech Connect

    Zheng, Dahuai; Yao, Jiaying; Kong, Yongfa; Liu, Shiguo; Zhang, Ling; Chen, Shaolin; Xu, Jingjun

    2015-01-15

    Bismuth-doped lithium niobate (LN:Bi) crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi) reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm{sup 2}). An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  15. Strong tendency of homeotropic alignment and anisotropic lithium ion conductivity of sulfonate functionalized zwitterionic imidazolium ionic liquid crystals.

    PubMed

    Rondla, Rohini; Lin, Joseph C Y; Yang, C T; Lin, Ivan J B

    2013-09-17

    Here, we report the first attempt to investigate the liquid crystal (LC) behavior of SO3(-) functionalized imidazolium zwitterionic (SO3(-)ImZI) salts, which display homeotropic alignment on a glass slide without the aid of any aligning approach. Doping lithium salt to ImZI salts lowers the melting temperatures and raises the clearing temperatures substantially to form room temperature ImZILCs. Excellent anisotropic lithium ion conductivity is achieved; which is strengthened by their tendency for homeotropic alignment. PMID:24010889

  16. EPR and optical absorption study of Cu2+ doped lithium sulphate monohydrate (LSMH) single crystals

    NASA Astrophysics Data System (ADS)

    Sheela, K. Juliet; Krishnan, S. Radha; Shanmugam, V. M.; Subramanian, P.

    2016-05-01

    EPR study of Cu2+ doped NLO active Lithium Sulphate monohydrate (Li2SO4.H2O) single crystals were grown successfully by slow evaporation method at room temperature. The principal values of g and A tensors indicate existence of orthorhombic symmetry around the Cu2+ ion. From the direction cosines of g and A tensors, the locations of Cu2+ in the lattice have been identified as interstitial site. Optical absorption confirms the rhombic symmetry and ground state wave function of the Cu2+ ion in a lattice as dx2-y2.

  17. Mode analysis of photonic crystal L3 cavities in self-suspended lithium niobate membranes

    SciTech Connect

    Diziain, Séverine Geiss, Reinhard; Zilk, Matthias; Schrempel, Frank; Kley, Ernst-Bernhard; Pertsch, Thomas; Tünnermann, Andreas

    2013-12-16

    We report on a multimodal analysis of photonic crystal L3 cavities milled in lithium niobate free-standing membranes. The classical L3 cavity geometry is compared to an L3 cavity containing a second lattice superimposed on the primary one. Those two different geometries are investigated in terms of vertical radiation and quality (Q) factor for each mode of the cavities. Depending on the cavity geometry, some modes undergo an enhancement of their vertical radiation into small angles while other modes experience a higher Q factor. Experimental characterizations are corroborated by three-dimensional finite difference time domain simulations.

  18. Absorption spectra and optical parameters of lithium-potassium sulphate single crystals

    NASA Astrophysics Data System (ADS)

    El-Fadl, A. Abu; Gaffar, M. A.; Omar, M. H.

    1999-09-01

    The optical transmittance and reflectance near the fundamental absorption region along the c- and a-axes of lithium potassium sulphate single crystal (LKS) are measured at room temperature. From the data the absorption coefficient ( α) and the optical band gap ( Eopt.g) were deduced. The type of transition was determined. The steepness parameter ( σ), the temperature dependence of the energy gap and the exciton energy ( E0) were also calculated. The extinction coefficient, the refractive index and both the real and imaginary parts of the dielectric permittivity were calculated as functions of the photon energy.

  19. Reflection measurement technique of electro-optic coefficients in lithium niobate crystals and poled polymer films

    NASA Astrophysics Data System (ADS)

    Shuto, Yoshito; Amano, Michiyuki

    1995-05-01

    An experimental arrangement for linear electro-optic (EO) measurements at wavelength 1.31 micron was described, the principle of which was the comparative determination of the phase-modulation indices by a reflection method. This method was used to measure the r(sub 33) values of both lithium niobate crystal and diazo-dye substituted poled polymers. Second harmonic generation (SHG) and EO effects were both depicted by a second-order susceptibility tensor. Finally, a comparison between the SHG and EO coefficients of the diazo-dye-substituted poled polymer films was presented.

  20. Isothermal Analysis of the Crystallization Kinetics in Lithium Disilicate Glass using Trans Temp Furnace

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Ray, C. S.; Day, D. E.

    2006-01-01

    Crystallization kinetics for lithium disilicate, Li2O2SiO2, (LS2) glass has been studied extensively by nonisothermal methods, but only a few studies on the isothermal crystallization kinetics of LS2 are available. In the present research, isothermal crystallization experiments or the LS2 glass were conducted in a Trans Temp furnace between 600 and 635 C, and selected properties such as the activation energy for crystallization (E), crystal growth index or Avrami parameter (n), the concentration of quenched-in nuclei in the starting glass (Ni) and the crystal nucleation rate (I) were measured. The crystal nucleation rate (I) was measured at only one selected temperature of 452 C, at this time. This commercial furnace has a 13 cm long isothermal heating zone (+/- 1 C) that allows precise heat treatment of relatively large samples. By placing a thermocouple within approx. 2 mm of the sample, it was possible to detect the heat of crystallization in the form of an isothermal crystallization exotherm during isothermal heat treatment of the sample. The values of E (318 plus or minus 10 kJ/mol), n (3.6 plus or minus 0.l), and N(sub i) (1.6 x 10(exp l2) m(sup -3)) calculated by analyzing these isotherms using the standard Johnson-Mehl-Avrami (JMA) equation were reproducible and in agreement with the literature values. The value of I, 1.9 x 10(exp 10) m(sup -3) s(sup -1) at 452 C, is an order of magnitude higher than the reported value for LS2.

  1. Crystal field splitting of the 4f 5d electronic configuration of Pr 3+ ions in wide band gap fluoride dielectric crystals

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, E.; Kollia, Z.; Cefalas, A. C.; Semashko, V. V.; Yu. Abdulsabirov, R.; Naumov, A. K.; Korableva, S. L.; Szczurek, T.; Kobe, S.; McGuiness, P. J.

    2002-07-01

    The absorption and the laser-induced fluorescence spectra of Pr 3+ ion in YF 3, LaF 3, KY 3 F 10 and LiLuF 4, single crystal hosts were obtained in the vacuum ultraviolet region of the spectrum. The energy position and the spacing of the levels of the 4f 5d electronic configuration depend on the host matrix. In addition, strong vacuum ultraviolet emission bands were observed, following crystal excitation at 157 nm with the molecular fluorine laser. The emission bands were due to the interconfigurational 4 f 5 d→4 f2 dipole-allowed transitions in Pr 3+ ions, and they were assigned to the transitions between the edge of the lowest Stark component of the 4f 5d electronic configuration and the levels of the 4f 2 electronic configuration. The VUV spectra can be interpreted by applying the crystal field model, and taking into consideration that lanthanide contraction of the 4f n-1 5d electronic configurations of the rare earth ions, and shielding of the positive ion charge from the electrons in the 4f n electronic configuration is taking place. Finally, a new method for monitoring the concentration of the rare earth ions in wide band gap fluoride dielectric crystals in a non-destructive way, by measuring magnetic dipole moments with the vibrating sample magnetometer (VSM) method, is presented for the first time to our knowledge for this type of crystals.

  2. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Shi, Feifei; Song, Zhichao; Ross, Philip N.; Somorjai, Gabor A.; Ritchie, Robert O.; Komvopoulos, Kyriakos

    2016-06-01

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives.

  3. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries

    PubMed Central

    Shi, Feifei; Song, Zhichao; Ross, Philip N.; Somorjai, Gabor A.; Ritchie, Robert O.; Komvopoulos, Kyriakos

    2016-01-01

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives. PMID:27297565

  4. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries.

    PubMed

    Shi, Feifei; Song, Zhichao; Ross, Philip N; Somorjai, Gabor A; Ritchie, Robert O; Komvopoulos, Kyriakos

    2016-06-14

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives.

  5. Polymeric ionic liquid-plastic crystal composite electrolytes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Zhang, Zhengxi; Li, Sijian; Yang, Li; Hirano, Shin-ichi

    2016-03-01

    In this work, composite polymer electrolytes (CPEs), that is, 80%[(1-x)PIL-(x)SN]-20%LiTFSI, are successfully prepared by using a pyrrolidinium-based polymeric ionic liquid (P(DADMA)TFSI) as a polymer host, succinonitrile (SN) as a plastic crystal, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt. XRD and DSC measurements confirm that the as-obtained CPEs have amorphous structures. The 80%[50%PIL-50%SN]-20%LiTFSI (50% SN) electrolyte reveals a high room temperature ionic conductivity of 5.74 × 10-4 S cm-1, a wide electrochemical window of 5.5 V, as well as good mechanical strength with a Young's modulus of 4.9 MPa. Li/LiFePO4 cells assembled with the 50% SN electrolyte at 0.1C rate can deliver a discharge capacity of about 150 mAh g-1 at 25 °C, with excellent capacity retention. Furthermore, such cells are able to achieve stable discharge capacities of 131.8 and 121.2 mAh g-1 at 0.5C and 1.0C rate, respectively. The impressive findings demonstrate that the electrolyte system prepared in this work has great potential for application in lithium ion batteries.

  6. Resonance laser-plasma excitation of coherent terahertz phonons in the bulk of fluorine-bearing crystals under high-intensity femtosecond laser irradiation

    SciTech Connect

    Potemkin, F V; Mareev, E I; Khodakovskii, N G; Mikheev, P M

    2013-08-31

    The dynamics of coherent phonons in fluorine-containing crystals was investigated by pump-probe technique in the plasma production regime. Several phonon modes, whose frequencies are overtones of the 0.38-THz fundamental frequency, were simultaneously observed in a lithium fluoride crystal. Phonons with frequencies of 1 and 0.1 THz were discovered in a calcium fluoride crystal and coherent phonons with frequencies of 1 THz and 67 GHz were observed in a barium fluoride crystal. Furthermore, in the latter case the amplitudes of phonon mode oscillations were found to significantly increase 15 ps after laser irradiation. (interaction of laser radiation with matter)

  7. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns.

    PubMed

    Kim, Jae-Hong; Oh, Seunghan; Uhm, Soo-Hyuk

    2016-01-01

    The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM) system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice-before and after crystallization-using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α = 0.05). Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P < 0.05). None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold. PMID:27123453

  8. A Novel Coupled Resonator Photonic Crystal Design in Lithium Niobate for Electrooptic Applications

    DOE PAGES

    Ozturk, Birol; Yavuzcetin, Ozgur; Sridhar, Srinivas

    2015-01-01

    High-aspect-ratio photonic crystal air-hole fabrication on bulk Lithium Niobate (LN) substrates is extremely difficult due to its inherent resistance to etching, resulting in conical structures and high insertion losses. Here, we propose a novel coupled resonator photonic crystal (CRPC) design, combining a coupled resonator approach with that of Bragg gratings. CRPC design parameters were optimized by analytical calculations and FDTD simulations. CRPC structures with optimized parameters were fabricated and electrooptically tested on bulk LN annealed proton exchange waveguides. Low insertion loss and large electrooptic effect were observed with the fabricated devices, making the CRPC design a promising structure for electroopticmore » device applications.« less

  9. Lithium vanadyl oxalatophosphite: Influence of the water content on the crystal structures and the dehydration scheme

    NASA Astrophysics Data System (ADS)

    Auguste, S.; Alonzo, V.; Bataille, T.; Le Pollès, L.; Cañón-Mancisidor, W.; Venegas-Yazigi, D.; Le Fur, E.

    2014-03-01

    Two new lithium vanadyl oxalatophosphites have been synthesized by hydrothermal treatment. The respective formula are Li2(VOHPO3)2C2O4 6H2O (1) and Li2(VOHPO3)2C2O4 4H2O (2). The structures of the compounds have been determined by single crystal X-ray diffraction. Compound 1 crystallizes in triclinic symmetry in space group P-1, a=6.3592(2) Å, b=8.0789(3) Å, c=9.1692(3) Å, α=64.390(2), β=87.277(2)°, γ=67.624(2) and, compound 2 in monoclinic symmetry, space group P21/a, a=6.3555(2) Å b=12.6368(7) Å c=9.0242(4) Å β=105.167(3)°. The vanadium phosphite framework consists of infinite chains of corner-sharing vanadium octahedra and hydrogenophosphite tetrahedra. The oxalate groups ensure the connection between the chains. The lithium ions and the water molecules are located between the anionic [(VO)2(HPO3)2C2O4]2- layers. Thermal behavior of both compounds was carefully studied by combining thermogravimetric analyses and thermal dependant X-ray diffraction in order to study the thermal stability of the layered oxalatophosphites and to see the influence of the decomposition of the carbon-based anions into the final lithium vanadyl phosphate. Various intermediate phases were evidenced and for both compounds the final product was LiVOPO4.

  10. Bending waveguides made in x-cut lithium niobate crystals for technological applications

    NASA Astrophysics Data System (ADS)

    Guarepi, V.; Perrone, C.; Aveni, M.; Videla, F.; Torchia, GA

    2015-12-01

    In this paper we analyse the performance of several designs of integrated optical deviators made in x-cut lithium niobate crystals by means of femtosecond laser writing using the double line approach. Straight and bent guiding structures have been designed and implemented using this technique. Well-confined propagation modes at communication wavelengths (1.55 μm) were conducted in these structures with acceptable overall losses (less than 2 dB cm-1). Further, a discussion about the optical propagation losses for curved and straight deviators devices is included in this work. At a low aperture angle (less than 0.2°), as expected, low losses were determined for both structures; however, a weak output light was observed for large angles (greater than 0.2°) in the straight optical circuits. In contrast, a smooth variation of the output was measured for the bent structures. The results presented in this paper support the possibility of the technological implementation of integrated optical circuits for optical communications fabricated with ultrashort laser writing in lithium niobate crystals. In addition, some hypotheses of loss mechanisms that are normally not considered are discussed in order to explain the differences between the measured values and predictions obtained by calculating with the usual models.

  11. Fluoridation Basics

    MedlinePlus

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Water Fluoridation Basics Recommend on Facebook Tweet Share Compartir ... because of tooth decay. History of Fluoride in Water In the 1930s, scientists examined the relationship between ...

  12. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns

    PubMed Central

    Kim, Jae-Hong; Oh, Seunghan; Uhm, Soo-Hyuk

    2016-01-01

    The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM) system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice—before and after crystallization—using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α = 0.05). Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P < 0.05). None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold. PMID:27123453

  13. The comparison of calculated transition probabilities with luminescence characteristics of erbium(III) in fluoride glasses and in the mixed yttrium-zirconium oxide crystal

    NASA Astrophysics Data System (ADS)

    Reisfeld, R.; Katz, G.; Jacoboni, C.; De Pape, R.; Drexhage, M. G.; Brown, R. N.; Jørgensen, C. K.

    1983-07-01

    Fluorozirconate glasses containing 2 mole% ErF 3 were prepared by melting the binary fluorides with ammonium bifluoride under an atmosphere of carbon tetrachloride and argon at 850°C. Absorption spectra of these glasses were obtained and the Judd-Ofelt parameters were calculated. Emission spectra and lifetimes of erbium in fluorozirconate glass, in lead-gallium-zinc fluoride glass, and in yttrium-zirconium oxide crystal were measured and compared with the theoretical calculations. Laser emission lines in these materials are deduced from these measurements. It is suggested that materials doped with erbium may serve as light sources for fiber optic waveguides made from the undoped materials.

  14. Crystal structure of a lithium salt of a glucosyl derivative of lithocholic acid.

    PubMed

    Gubitosi, Marta; Meijide, Francisco; D'Annibale, Andrea; Vázquez Tato, José; Jover, Aida; Galantini, Luciano; Travaglini, Leana; di Gregorio, Maria Chiara; Pavel, Nicolae V

    2016-09-01

    The crystal structure of a Li(+) salt of a glucosyl derivative of lithocholic acid (lithium 3α-(α-d-glucopyranosyl)-5β-cholan-24-oate) has been solved. The crystal belongs to the orthorhombic system, P212121 spatial group, and includes acetone and water in the structure with a 1:1:2 stoichiometry. Monolayers, having a hydrophobic interior and hydrophilic edges, are recognized in the crystal structure. Li(+) is coordinated to three hydroxyl groups of three different glucose residues, with two of them belonging to the same monolayer. A fourth molecule, located in this monolayer, is involved in the coordination of the cation through the carboxylate ion by an electrostatic interaction, thus completing a distorted tetrahedron. All Li(+)-oxygen distances values are very close to the sum of the ionic radius of Li(+) and van der Waals radius of oxygen. Each steroid molecule is linked to other five steroid molecules through hydrogen bonds. Water and acetone are also involved in the hydrogen bond network. A hierarchical organization can be recognized in the crystal, the helical assembly along 21 screw axes being left-handed. PMID:27394960

  15. Development of a versatile high temperature top seeded solution growth unit for growing cesium lithium borate crystals.

    PubMed

    Reddy, Babu; Elizabeth, Suja; Bhat, H L; Karnal, A K

    2009-01-01

    The design and fabrication of a state of the art high temperature top seeded solution growth (HTTSSG) unit with seed and crucible rotation options is discussed. Crystals from solid solutions of high viscosity could be grown using the setup. The fabricated setup is used to grow high optical quality single crystals of cesium lithium borate with dimensions 50x40x40 mm(3) for frequency conversion of ir to UV laser through harmonic generation.

  16. Bis(glycine) lithium nitrate - A new non-centrosymmetric crystal: X-ray structure, vibrational spectra and DSC investigations

    NASA Astrophysics Data System (ADS)

    Baran, J.; Drozd, M.; Ratajczak, H.; Pietraszko, A.

    2009-06-01

    A new complex of glycine with lithium nitrate in the molecular ratio 2:1 (bis(glycine) lithium nitrate; abbreviated as BGLiN) was obtained. Its crystal belongs to the Pca2 1 space group of the orthorhombic system; Z = 4. The lattice parameters are as follows: a = 10.224(12), b = 5.0343(6) and c = 17.051(2) Å. The structure is built up of the layers being parallel to the ab crystallographic plane. The lithium cations are surrounded by four oxygen atoms deriving from the glycine zwitterions. The structure and vibrational spectra (IR and Raman) of the title crystal are discussed with respect to one other and to those of glycine lithium nitrate (GLiN) and glycine sodium nitrate (GNaN) crystals. The DSC investigations do not show any low temperature phase transition (till ca. 110 K) neither for the BGLiN nor the GLiN crystals. At high temperatures the discontinuous weak phase transition followed by the melting is observed for both these complexes.

  17. The structural and electrochemical dynamics of the electrode-electrolyte interphase of metal fluoride nanocomposite positive electrodes for lithium batteries

    NASA Astrophysics Data System (ADS)

    Gmitter, Andrew John

    Metal fluorides are attractive for use as positive electrodes in Li and Li-ion batteries because of their high gravimetric and volumetric energy densities. When synthesized into nanocomposites, these materials undergo conversion reactions and exhibit near theoretical specific capacity and good rate capability. Despite these positive attributes, metal fluorides nanocomposites generally exhibit unacceptable rates of capacity loss during cycling. This stands as a significant barrier to their realization as a viable battery technology. This thesis explored a candidate material, BiF3, and for the first time, the mechanisms by which metal fluoride nanocomposite positive electrode materials fail during cycling have been investigated. The chemistry of the electrode / electrolyte interface and its influence on the BiF3 material were of greatest interest. Early in the course of study, it was discovered that the Bi0 metal produced through the discharge reaction of BiF3 was a catalytically active site for the electrochemical reduction of ethylene carbonate (EC) at potentials exceeding 2 V vs. Li/Li+. This potential range is well above the values typically observed on carbonaceous negative electrodes on which preferential reduction of electrolyte species yields insoluble phases. These ionically conducting layers are deemed solid-electrolyte interphases (SEI), and in the case of carbonaceous materials, they are necessary for enabling functionality of the electrode and preventing deleterious interactions with the electrolyte. Thorough electrochemical and spectroscopic examinations identified Li2CO3 as the predominant SEI species formed on Bi0 from EC. In stark contrast to carbonaceous materials, the presence of SEI on Bi0 was detrimental to the cycling performance of BiF3. Elaboration of this topic identified instability of the SEI during the charging process of the BiF3 and the formation of BiOxF3-2x in the fully charged state. Electrolytes composed of linear

  18. Preparation and characterization of lithium ion conducting polymer electrolytes based on a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and poly(methyl methacrylate).

    PubMed

    Gebreyesus, Merhawi Abreha; Purushotham, Y; Kumar, J Siva

    2016-07-01

    Ion conducting polymer electrolytes composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), poly(methyl methacrylate) (PMMA) and lithium triflate (LiTf) were prepared using the solution casting method. Structural change and complex formation in the blend electrolyte systems were confirmed from the X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) studies. Thermal properties of the samples were investigated by the differential scanning calorimetry (DSC) technique. The ionic conductivity of these polymer electrolytes was studied by impedance spectroscopy at various temperatures ranging from 303-393 K. The results reveal that the ionic conductivity of the polymer blend electrolytes depends on the PVdF-HFP:PMMA composition as well as the temperature. Maximum room temperature conductivity of [Formula: see text] S cm(-1) was achieved with 22.5 wt.% PMMA. The blending of PVdF-HFP with PMMA improved the thermal stability and ionic conductivity of the polymer electrolyte. Estimated transference numbers suggest the charge transport is predominantly ionic. PMID:27512728

  19. Electro-Spun Poly(vinylidene fluoride) Nanofiber Web as Separator for Lithium Ion Batteries: Effect of Pore Structure and Thickness.

    PubMed

    Lim, Seung-Gyu; Jo, Hye-Dam; Kim, Chan; Kim, Hee-Tak; Chang, Duck-Rye

    2016-01-01

    Electro-spun nanofiber web is highly attractive as a separator for lithium ion batteries because of its high electrical properties. In moving toward wider battery applications of the nanofiber separators, a deeper understanding on the structure and property relationship is highly meaningful. In this regard, we prepared electro-spun poly(vinylidene fluoride) (PVdF) webs with various thicknesses (10.5~100 µm) and investigated their structures and electrochemical performances. As the thickness of the web is decreased, a decrease of porosity and an increase of pore size are resulted in. For the 10.5 µm-thick separator, a minor short-circuit was detected, stressing the importance of reducing pore-size on prevention of short-circuit. However, above the thickness of 21 µm, well-connected, submicron-sized pores are generated, and, with lowering the separator thickness, discharge capacity and rate capability are enhanced owing to the lowered area-specific resistance. PMID:27398553

  20. Some Lower Valence Vanadium Fluorides: Their Crystal Distortions, Domain Structures, Modulated Structures, Ferrimagnetism, and Composition Dependence.

    ERIC Educational Resources Information Center

    Hong, Y. S.; And Others

    1980-01-01

    Describes some contemporary concepts unique to the structure of advanced solids, i.e., their crystal distortions, domain structures, modulated structures, ferrimagnetism, and composition dependence. (Author/CS)

  1. Lithium vanadyl oxalatophosphite: Influence of the water content on the crystal structures and the dehydration scheme

    SciTech Connect

    Auguste, S.; Alonzo, V.; Bataille, T.; Le Pollès, L.; Cañón-Mancisidor, W.; Venegas-Yazigi, D.; Le Fur, E.

    2014-03-15

    Two new lithium vanadyl oxalatophosphites have been synthesized by hydrothermal treatment. The respective formula are Li{sub 2}(VOHPO{sub 3}){sub 2}C{sub 2}O{sub 4} 6H{sub 2}O (1) and Li{sub 2}(VOHPO{sub 3}){sub 2}C{sub 2}O{sub 4} 4H{sub 2}O (2). The structures of the compounds have been determined by single crystal X-ray diffraction. Compound 1 crystallizes in triclinic symmetry in space group P-1, a=6.3592(2) Å, b=8.0789(3) Å, c=9.1692(3) Å, α=64.390(2), β=87.277(2)°, γ=67.624(2) and, compound 2 in monoclinic symmetry, space group P2{sub 1}/a, a=6.3555(2) Å b=12.6368(7) Å c=9.0242(4) Å β=105.167(3)°. The vanadium phosphite framework consists of infinite chains of corner-sharing vanadium octahedra and hydrogenophosphite tetrahedra. The oxalate groups ensure the connection between the chains. The lithium ions and the water molecules are located between the anionic [(VO){sub 2}(HPO{sub 3}){sub 2}C{sub 2}O{sub 4}]{sup 2−} layers. Thermal behavior of both compounds was carefully studied by combining thermogravimetric analyses and thermal dependant X-ray diffraction in order to study the thermal stability of the layered oxalatophosphites and to see the influence of the decomposition of the carbon-based anions into the final lithium vanadyl phosphate. Various intermediate phases were evidenced and for both compounds the final product was LiVOPO{sub 4}. -- Graphical abstract: Two new lithium vanadyl oxalatophosphites layered compounds, Li{sub 2} (VOHPO{sub 3}){sub 2}C{sub 2}O{sub 4} 6H{sub 2}O (1) and Li{sub 2} (VOHPO{sub 3}){sub 2}C{sub 2}O{sub 4} 4H{sub 2}O (2) have been hydrothermally synthesized. Lithium ions and water molecules are located between the anionic [(VO){sub 2}(HPO{sub 3}){sub 2}C{sub 2}O{sub 4}]{sup 2−} layers. Thermal behaviors were carefully studied by thermogravimetric and thermal dependant X-ray diffraction. Various intermediate phases were evidenced and for both compounds the final product was LiVOPO{sub 4}. Highlights: • The first

  2. [Study on the vacuum ultraviolet transmittance of barium fluoride crystals at different temperature].

    PubMed

    Peng, Ru-Yi; Fu, Li-Ping; Tao, Ye

    2014-03-01

    Two VUV-grade BaF2 windows with 0.5 mm-thick and 1 mm-thick respectively were selected to study the transmittance variety with the temperature. The results show that the cutoff wavelength of BaF2 crystals will shift towards the long wave with the increase in temperature. In a certain temperature range, BaF2 crystals can depress 130.4 nm radiation well, and also has a high transmittance at 135.6 nm. Compared with the reported method in which SrF2 crystals can be applied to suppress 130.4 nm stray light by heating, BaF2 crystal can inhibit the 130. 4 nm emission line completely, and thus reduce the power consumption of the device at the same time. This indicates that BaF2 crystals can play an important role in the ionosphere optical remote sensing detection. PMID:25208398

  3. Low-Temperature Fluorination of Soft-Templated Mesoporous Carbons for a High-Power Lithium/Carbon Fluoride Battery

    SciTech Connect

    Fulvio, Pasquale F; Dai, Sheng; Guo, Bingkun; Mahurin, Shannon Mark; Mayes, Richard T; Sun, Xiao-Guang; Veith, Gabriel M; Brown, Suree; Adcock, Jamie

    2011-01-01

    Soft-templated mesoporous carbons and activated mesoporous carbons were fluorinated using elemental fluorine between room temperature and 235 C. The mesoporous carbons were prepared via self-assembly synthesis of phloroglucinol formaldehyde as a carbon precursor in the presence of triblock ethylene oxide propylene oxide ethylene oxide copolymer BASF Pluronic F127 as the template. The F/C ratios ranged from 0.15 to 0.75 according to gravimetric, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. Materials have mesopore diameters up to 11 nm and specific surface areas as high as 850 m2 g 1 after fluorination as calculated from nitrogen adsorption isotherms at 196 C. Furthermore, the materials exhibit higher discharge potentials and energy and power densities as well as faster reaction kinetics under high current densities than commercial carbon fluorides with similar fluorine contents when tested as cathodes for Li/CFx batteries.

  4. Crystal structure and chemistry of lithium-bearing trioctahedral micas-3T

    USGS Publications Warehouse

    Brigatti, M.F.; Kile, D.E.; Poppi, L.

    2003-01-01

    Chemical analyses and crystal structure refinements were performed on lithian siderophyllite-3T crystals from granitic pegmatites of the anorogenic Pikes Peak batholith (Colorado) to characterize the crystal chemistry and relations with trioctahedral lithium-bearing micas showing different stacking sequences. Chemical data show that the studied samples fall on the siderophyllite-polylithionite join, closer to the siderophyllite end-member. Single-crystal X-ray refinements were carried out on three samples (two of which were taken from core and rim of the same crystal) in space-group P31 12 (the agreement factor, Robs, varies between 0.034 and 0.036). Mean bond distances and mean electron counts of M1, M2 and M3 octahedral sites indicate an ordered cation distribution with M1 and M3 positions substantially larger than M2. In the sample with the largest iron content, the M2 mean electron count increases as well as the mean distance, whereas remains smaller than or . The tetrahedral cation-oxygen atom mean distances range from 1.614 to 1.638 A?? and from 1.663 to 1.678 A?? for T1 and T2 sites, respectively, being consistent with Al3+ enrichment in the T2 sites. The tetrahedral rotation angle, ??, is generally small (3.1 ??? ?? ??? 4.6??) and decreases with siderophyllite content. As Fe increases, the T1 tetrahedron becomes flatter (112.4 ??? t??1 ??? 110.5??), whereas T2 tetrahedron distortion appears unchanged (110.7 ??? t??T2 ??? 110.9).

  5. Fabrication and Characterization of Linear Terahertz Detector Arrays Based on Lithium Tantalate Crystal

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Wang, Jun; Gou, Jun; Huang, Zehua; Jiang, Yadong

    2015-01-01

    Two samples of 30-pixel linear terahertz detector arrays (TDAs) were fabricated based on lithium tantalate (LT) crystals. Pixel readout circuit (ROC) was designed to extract the weak current signal of TDAs. A test platform was established for performance evaluation of TDA+ROC components. By using a 2.52THz laser as radiation source, the test results reveal that average voltage responsivities of the components were larger than 7000V/W and non-uniformity no more than 2.1%. Average noise equivalent power ( NEP) of one sample was measured to be 1.5×10-9 W/Hz1/2, which is low enough and desirable for high performance THz detector.

  6. Formation of snowflake domains during fast cooling of lithium tantalate crystals

    NASA Astrophysics Data System (ADS)

    Shur, V. Ya.; Kosobokov, M. S.; Mingaliev, E. A.; Kuznetsov, D. K.; Zelenovskiy, P. S.

    2016-04-01

    Formation of the original dendrite snowflake-shape domains during fast cooling after heating above phase transition temperature by pulse laser irradiation was revealed in congruent lithium tantalate crystals. The effect was attributed to polarization reversal under the action of spatially nonuniform pyroelectric field. Two stages of the domain shape evolution at the surface were separated: (1) growth of circular domains by sideways motion of the domain walls and (2) backswitching leading to formation of the snowflake domains. The simulated spatial distribution of the pyroelectric field in regular two-dimensional structure was used for an explanation of the obtained results. The backswitching process in the surface layer has been attributed to change of the sign of the pyroelectric field at the domain wall. The snowflake domain shape is caused by the formation of isolated nanodomain fingers and hampering of their merging.

  7. High-capacity lithium-ion battery conversion cathodes based on iron fluoride nanowires and insights into the conversion mechanism.

    PubMed

    Li, Linsen; Meng, Fei; Jin, Song

    2012-11-14

    The increasing demands from large-scale energy applications call for the development of lithium-ion battery (LIB) electrode materials with high energy density. Earth abundant conversion cathode material iron trifluoride (FeF(3)) has a high theoretical capacity (712 mAh g(-1)) and the potential to double the energy density of the current cathode material based on lithium cobalt oxide. Such promise has not been fulfilled due to the nonoptimal material properties and poor kinetics of the electrochemical conversion reactions. Here, we report for the first time a high-capacity LIB cathode that is based on networks of FeF(3) nanowires (NWs) made via an inexpensive and scalable synthesis. The FeF(3) NW cathode yielded a discharge capacity as high as 543 mAh g(-1) at the first cycle and retained a capacity of 223 mAh g(-1) after 50 cycles at room temperature under the current of 50 mA g(-1). Moreover, high-resolution transmission electron microscopy revealed the existence of continuous networks of Fe in the lithiated FeF(3) NWs after discharging, which is likely an important factor for the observed improved electrochemical performance. The loss of active material (FeF(3)) caused by the increasingly ineffective reconversion process during charging was found to be a major factor responsible for the capacity loss upon cycling. With the advantages of low cost, large quantity, and ease of processing, these FeF(3) NWs are not only promising battery cathode materials but also provide a convenient platform for fundamental studies and further improving conversion cathodes in general.

  8. Effects of copper, iron and fluoride co-crystallized with sugar on caries development and acid formation in deslivated rats.

    PubMed

    Rosalen, P L; Pearson, S K; Bowen, W H

    1996-11-01

    The purpose was to explore the effects of combinations of copper, iron and fluoride (Cu, Fe and F) incorporated in sucrose by co-crystallization on caries development in the deslivated rat model and to examine acid formation by bacteria in the rat mouth. Ninety-six Sprague-Dawley rats were infected with Streptococcus sobrinus 6715 and desalivated when aged 26 days. Eight groups were placed in a König-Höfer programmed feeder and received 17 meals daily at hourly intervals, and essential nutrition (NCP No. 2) by gavage twice daily for 21 days. The groups received (1) plain sucrose, (2) F (8 parts/10(6)) co-crystallized with sucrose, (3) Fe (88 parts/10(6)) sucrose, (4) Cu (75 parts/10(6)) sucrose, (5) Cu + F sucrose, (6) Cu + L Fe sucrose, (7) F + Fe sucrose, and (8) Cu + Fe + F sucrose. At death the jaws were removed and sonicated in 0.9% saline solution for microbial assessment. In addition, organic acid assays were performed for each animal. Keyes smooth-surface and sulcal caries scores were lowest in the Cu + Fe + F sucrose group, but not statistically significantly different from those of the other Cu groups. The numbers of Strep. sobrinus found in the groups that received Cu, Cu + Fe, Cu + F, F + Fe and Cu + Fe + F sugar were lower than in the control group. Lactic acid was found in lower concentrations in Fe, Cu, Cu + F, Cu + Fe and F + Fe groups than in the other groups. It appears that combinations of Cu; Fe and F co-crystallized with sugar may have an additive effect in reducing the cariogenic potential of sugar by affecting lactic acid formation and reducing bacterial colonization.

  9. Low-Temperature Fluorination of Soft-Templated Mesoporous Carbons for a High-Power Lithium/Carbon Fluoride Battery

    SciTech Connect

    Fulvio, Pasquale F.; Brown, Suree S.; Adcock, Jamie; Mayes, Richard T.; Guo, Bingkun; Sun, Xiao-Guang; Mahurin, Shannon M.; Veith, Gabriel M.; Dai, Sheng

    2011-09-29

    Soft-templated mesoporous carbons and activated mesoporous carbons were fluorinated using elemental fluorine between room temperature and 235 °C. The mesoporous carbons were prepared via self-assembly synthesis of phloroglucinol–formaldehyde as a carbon precursor in the presence of triblock ethylene oxide–propylene oxide–ethylene oxide copolymer BASF Pluronic F127 as the template. The F/C ratios ranged from ~0.15 to 0.75 according to gravimetric, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. Materials have mesopore diameters up to 11 nm and specific surface areas as high as 850 m² g⁻¹ after fluorination as calculated from nitrogen adsorption isotherms at -196 °C. Furthermore, the materials exhibit higher discharge potentials and energy and power densities as well as faster reaction kinetics under high current densities than commercial carbon fluorides with similar fluorine contents when tested as cathodes for Li/CFx batteries.

  10. New luminescent systems based on fluoride crystals doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Ryba-Romanowski, W.; Solarz, P.; Dominiak-Dzik, G.; Gusowski, M.

    2006-01-01

    Results of recent investigation aimed at finding new efficient laser active materials and converters of VUV radiation into visible emission are summarised. Representatives of two families of compounds with general chemical formulae: K 5Li 2LnF 10 (Ln 3+ = Ce, La-Gd) and M 3LnF 6 (M + = K +, Cs +, Rb +; Ln 3+ = La-Yb) as well as a new compound Na 2K 2NdF 7 have been synthesised by a solid state reaction and next obtained in a single crystal form by the Bridgman method. Crystal structures of compounds have been ascertained based on X-ray measurement on single crystal samples. Spectroscopic properties of crystals have been determined based on optical absorption spectra, emission spectra and luminescence decay curves recorded at temperatures between 4.2 and 300 K in the UV-VIS-NIR spectral region. Optical properties and material parameters relevant to application of the crystals will be presented and discussed.

  11. Dynamics recording of holographic gratings in a photochromic crystal of calcium fluoride

    NASA Astrophysics Data System (ADS)

    Borisov, Vladimir N.; Barausova, Ekaterina V.; Veniaminov, Andrey V.; Andervaks, Alexandr E.; Shcheulin, Alexandr S.; Ryskin, Alexandr I.

    2016-08-01

    Dynamics of diffraction efficiency was monitored during recording a holographic grating in additively coloured CaF2 photochromic crystal at 180-200°C. Reciprocity failure revealed in the study was attributed to diffusion playing the crucial role in grating formation: recording at larger laser power goes faster but requires more energy. The efficiency of a recorded hologram is found to depend on the temperature; maximum diffraction is measured at the temperature far below that of recording, supposedly because of dramatic distortions suffered by the crystal along with exposure.

  12. Complex extraordinary dielectric function of Mg-doped lithium niobate crystals at terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Kuznetsov, K. A.; Kitaeva, G. Kh.; Kovalev, S. P.; Germansky, S. A.; Buryakov, A. M.; Tuchak, A. N.; Penin, A. N.

    2016-08-01

    We study the dispersion of the extraordinary dielectric function real and imaginary parts in the wide terahertz-frequency range of the lowest polariton branch for bulk LiNbO3 and Mg:LiNbO3 crystals. At frequencies 0.1-2.5 THz, both dispersion parts are measured by means of standard time-domain terahertz spectroscopy, and at higher frequencies up to 5.5 THz, the dielectric function real part is determined using a common scheme of spontaneous parametric down-conversion under near-forward Raman scattering by phonon polaritons. A special approach is applied for measuring of the dielectric function imaginary part at frequencies 1-3 THz, based on the analysis of visibility of three-wave second-order interference under spontaneous parametric down-conversion. The generalized approximate expressions are obtained for complex dielectric function dispersion within the lower polariton branches of LiNbO3 and Mg:LiNbO3. It is shown that the well-known decrease in terahertz-wave absorption of lithium niobate crystals under Mg-doping is caused by changes in the defect structure and reduction of coupling of the terahertz-frequency polaritons with Debye relaxational mode.

  13. Optimal Fluoridation

    PubMed Central

    Lee, John R.

    1975-01-01

    Optimal fluoridation has been defined as that fluoride exposure which confers maximal cariostasis with minimal toxicity and its values have been previously determined to be 0.5 to 1 mg per day for infants and 1 to 1.5 mg per day for an average child. Total fluoride ingestion and urine excretion were studied in Marin County, California, children in 1973 before municipal water fluoridation. Results showed fluoride exposure to be higher than anticipated and fulfilled previously accepted criteria for optimal fluoridation. Present and future water fluoridation plans need to be reevaluated in light of total environmental fluoride exposure. PMID:1130041

  14. Lithium in-diffusion treatment of thick LiNbO 3 crystals by the vapor transport equilibration method

    NASA Astrophysics Data System (ADS)

    Liang, Xinan; Xuewu, Xu; Tow-Chong, Chong; Shaoning, Yuan; Fengliang, Yu; Soon, Tay Yong

    2004-01-01

    Congruent LiNbO 3 (CLN) crystals with various orientations ( X-, Y- and Z-cut) and thickness (1-3.2 mm) were treated by the vapor transport equilibration (VTE) method in lithium-rich environment at 1100°C. Homogeneous and crack-free crystals with nearly stoichiometric composition (>49.9 mol% Li 2O) were obtained for different orientations. The cracking problem of X- and Y-cut samples was studied and solved by decreasing the cooling rate after the VTE treatment. The Li 2O content in the crystal was determined by the cutoff UV absorption edge of the crystal sample. For thick samples, the diffusion of lithium atoms from side faces had influenced the composition homogeneity of the VTE-treated crystals. The CLN crystal plates with thicknesses of around 2 mm were converted into stoichiometric LiNbO 3 (SLN) by the VTE method within 200 h. Thicker CLN samples would need longer time to be converted into SLN.

  15. Domain wall kinetics of lithium niobate single crystals near the hexagonal corner

    SciTech Connect

    Choi, Ju Won; Ko, Do-Kyeong; Yu, Nan Ei E-mail: jhro@pnu.edu; Kitamura, Kenji; Ro, Jung Hoon E-mail: jhro@pnu.edu

    2015-03-09

    A mesospheric approach based on a simple microscopic 2D Ising model in a hexagonal lattice plane is proposed to explain macroscopic “asymmetric in-out domain wall motion” observation in the (0001) plane of MgO-doped stoichiometric lithium niobate. Under application of an electric field that was higher than the conventional coercive field (E{sub c}) to the ferroelectric crystal, a natural hexagonal domain was obtained with walls that were parallel to the Y-axis of the crystal. When a fraction of the coercive field of around 0.1E{sub c} is applied in the reverse direction, this hexagonal domain is shrunk (moved inward) from the corner site into a shape with a corner angle of around 150° and 15° wall slopes to the Y-axis. A flipped electric field of 0.15E{sub c} is then applied to recover the natural hexagonal shape, and the 150° corner shape changes into a flat wall with 30° slope (moved outward). The differences in corner domain shapes between inward and outward domain motion were analyzed theoretically in terms of corner and wall site energies, which are described using the domain corner angle and wall slope with respect to the crystal Y-axis, respectively. In the inward domain wall motion case, the energy levels of the evolving 150° domain corner and 15° slope walls are most competitive, and could co-exist. In the outward case, the energy levels of corners with angles >180° are highly stable when compared with the possible domain walls; only a flat wall with 30° slope to the Y-axis is possible during outward motion.

  16. Quasicharacteristic radiation of relativistic electrons at orientation motion in lithium halides crystals along charged planes and axes

    NASA Astrophysics Data System (ADS)

    Maksyuta, N. V.; Vysotskii, V. I.; Efimenko, S. V.

    2016-07-01

    The paper deals with the investigation of the orientation motion of relativistic electrons in charged (111) planes and charged [110] axes of lithium halides ionic crystals of LiF, LiCl, LiBr and LiI. On the basis of these investigations the spectra of quasicharacteristic radiation for the electron beams with various Lorentz-factors both in planar and axial cases have been calculated numerically.

  17. Formation Dynamics of Transmission Holograms in Lithium Niobate Crystals Doped by Copper Through High-Temperature Diffusion

    NASA Astrophysics Data System (ADS)

    Mambetova, K. M.; Smal', N. N.; Shandarov, S. M.; Orlikov, L. N.; Arestov, S. I.; Smirnov, S. V.

    2015-01-01

    The results of experimental realization of the technology of diffusion doping of X-cut congruent lithium niobate crystals by copper and the results of studying their photorefractive and photovoltaic properties are presented. The latter was done by using the Bragg diffraction of the reading beam with a wavelength of 655 nm on the dynamic transmission volume-phase holograms recorded by laser beams having a wavelength of 532 nm. It is shown that by their photogalvanic properties the created samples, which are 1.8 mm thick, are similar to the single crystals grown by the conventional method from melt containing copper monooxide as a supplement.

  18. Development of fluorides for high power laser optics

    SciTech Connect

    Ready, J.F.; Vora, H.

    1980-07-01

    The laser-assisted thermonuclear fusion program has significant needs for improved optical materials with high transmission in the ultraviolet, and with low values of nonlinear index of refraction. Lithium fluoride (LiF) possesses a combination of optical properties which are of potential use. Single-crystalline LiF is limited by low mechanical strength. In this program, we investigated the technique of press-forging to increase the mechanical strength. LiF single crystals were press-forged over the temperature range 300 to 600/sup 0/C to produce fine-grained polycrystalline material.

  19. The mechanism of deceleration of nucleation and crystal growth by the small addition of transition metals to lithium disilicate glasses

    NASA Astrophysics Data System (ADS)

    Thieme, Katrin; Avramov, Isak; Rüssel, Christian

    2016-05-01

    The addition of small amounts of niobium or tantalum oxide to lithium disilicate glass provokes a drastic decrease of the steady-state nucleation rates and the crystal growth velocities. The viscosity of the residual glassy matrix is considered as a function of the crystallization degree in the course of a non-isothermal crystallization. For simplification, a homogeneous distribution of the added oxides in the glass matrix is assumed. While the viscosity initially decreases, it significantly increases again for higher crystallization degrees hindering crystal growth. However, it was shown that the additives are enriched at the crystal interface. Several possible reasons for the inhibition of nucleation and growth kinetics such as viscosity, interfacial energy crystal/glassy phase, thermodynamic driving force or impingement rate are discussed. Since the crystallization front is blocked by the additives the impingement rate is decreased with increasing additive concentration. Since small concentrations of Nb2O5 and Ta2O5 have a drastic effect on the nucleation, these components should be enriched at the interface crystal/glass. This will only take place, if it leads to a decrease in the interfacial energy. Since this effect alone should result in an increase of the nucleation rate, it must be overcompensated by kinetic effects.

  20. The mechanism of deceleration of nucleation and crystal growth by the small addition of transition metals to lithium disilicate glasses

    PubMed Central

    Thieme, Katrin; Avramov, Isak; Rüssel, Christian

    2016-01-01

    The addition of small amounts of niobium or tantalum oxide to lithium disilicate glass provokes a drastic decrease of the steady-state nucleation rates and the crystal growth velocities. The viscosity of the residual glassy matrix is considered as a function of the crystallization degree in the course of a non-isothermal crystallization. For simplification, a homogeneous distribution of the added oxides in the glass matrix is assumed. While the viscosity initially decreases, it significantly increases again for higher crystallization degrees hindering crystal growth. However, it was shown that the additives are enriched at the crystal interface. Several possible reasons for the inhibition of nucleation and growth kinetics such as viscosity, interfacial energy crystal/glassy phase, thermodynamic driving force or impingement rate are discussed. Since the crystallization front is blocked by the additives the impingement rate is decreased with increasing additive concentration. Since small concentrations of Nb2O5 and Ta2O5 have a drastic effect on the nucleation, these components should be enriched at the interface crystal/glass. This will only take place, if it leads to a decrease in the interfacial energy. Since this effect alone should result in an increase of the nucleation rate, it must be overcompensated by kinetic effects. PMID:27150844

  1. The mechanism of deceleration of nucleation and crystal growth by the small addition of transition metals to lithium disilicate glasses.

    PubMed

    Thieme, Katrin; Avramov, Isak; Rüssel, Christian

    2016-01-01

    The addition of small amounts of niobium or tantalum oxide to lithium disilicate glass provokes a drastic decrease of the steady-state nucleation rates and the crystal growth velocities. The viscosity of the residual glassy matrix is considered as a function of the crystallization degree in the course of a non-isothermal crystallization. For simplification, a homogeneous distribution of the added oxides in the glass matrix is assumed. While the viscosity initially decreases, it significantly increases again for higher crystallization degrees hindering crystal growth. However, it was shown that the additives are enriched at the crystal interface. Several possible reasons for the inhibition of nucleation and growth kinetics such as viscosity, interfacial energy crystal/glassy phase, thermodynamic driving force or impingement rate are discussed. Since the crystallization front is blocked by the additives the impingement rate is decreased with increasing additive concentration. Since small concentrations of Nb2O5 and Ta2O5 have a drastic effect on the nucleation, these components should be enriched at the interface crystal/glass. This will only take place, if it leads to a decrease in the interfacial energy. Since this effect alone should result in an increase of the nucleation rate, it must be overcompensated by kinetic effects. PMID:27150844

  2. Thermodynamic and kinetic characteristics of variations in shapes of ridges formed on l brace 100 r brace lithium fluoride surfaces

    SciTech Connect

    Bullard, J.W.; Glaeser, A.M.; Searcy, A.W.

    1991-12-01

    channels with widths in the range form 5 {mu}m were formed in {l brace}100{r brace} surfaces of LiF single crystals by a photolithographic technique. Specimens annealed at or above 0.90 T{mu}m, where T{mu} is the melting point, and then quenched showed the channels and the ridges between them develop rounded profiles. Evolution of these profiles was evaluated for the various channel widths and for interchannel ridge spacings of 5 to 100 {mu}m in terms of: (a) an accepted theoretical model for a surface diffusion controlled process, and (b) a model which assumes that shape changes depend only on the relative energies of attachment of atoms in surface sites with various surface curvatures. Either model is consistent with the experimental observations to within the reproducibility in measurements.

  3. Optical properties of Eu{sup 2+} doped antipervoskite fluoride single crystals

    SciTech Connect

    Daniel, D. Joseph; Ramasamy, P.; Nithya, R.; Madhusoodanan, U.

    2013-02-05

    Single crystals of pure and Eu{sup 2+} doped LiBaF{sub 3} have been grown from melt by using a vertical Bridgman-Stockbarger method. Absorption and luminescence spectra for pure and rare-earth-doped LiBaF{sub 3} were studied. At ambient conditions the photoluminescence spectra consisted of sharp lines peaked at {approx}359 nm attributed to the {sup 6}P7/2{yields}{sup 8}S7/2 transitions in the 4f{sub 7} electronic configuration of Eu{sup 2+} and a broad band extending between 370 and 450 nm attributed to Eu{sup 2+} trapped exciton recombination. The effect of {sup 60}Co gamma irradiation has also been investigated.

  4. Models of tetrahedral rare-earth clusters in cadmium fluoride crystals and paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Vazhenin, V. A.; Chernyshev, V. A.; Guseva, V. B.; Potapov, A. P.; Artyomov, M. Yu.

    2008-03-01

    The parameters of the zero-field level splitting of Gd3+ ions localized in three kinds of tetrahedral clusters are estimated within the superposition approximation. The structure of a cluster is determined by minimizing the energy of the crystal with the embedded cluster. As a result, the strong monoclinic EPR spectrum with b 20 = -345 MHz is attributed to the [CdY2CdF26] cluster and a weaker spectrum with b 20 ≈ -600 MHz is attributed to [Cd2YGdF26]. The difference between the absolute values of the calculated and experimental parameters b 20 is explained by the fact that the experimental spectrum is due to gadolinium ions located in clusters that are part of associations.

  5. Polymorphic Crystallization and Crystalline Reorganization of Poly(l-lactic acid)/Poly(d-lactic acid) Racemic Mixture Influenced by Blending with Poly(vinylidene fluoride).

    PubMed

    Yu, Chengtao; Han, Lili; Bao, Jianna; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

    2016-08-18

    The effects of poly(vinylidene fluoride) (PVDF) on the crystallization kinetics, competing formations of homocrystallites (HCs) and stereocomplexes (SCs), polymorphic crystalline structure, and HC-to-SC crystalline reorganization of the poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic mixture were investigated. Even though the PLLA/PDLA/PVDF blends are immiscible, blending with PVDF enhances the crystallization rate and SC formation of PLLA/PDLA components at different temperatures that are higher or lower than the melting temperature of the PVDF component; it also facilitates the HC-to-SC melt reorganization upon heating. The crystallization rate and degree of SC crystallinity (Xc,SC) of PLLA/PDLA components in nonisothermal crystallization increase after immiscible blending with PVDF. At different isothermal crystallization temperatures, the crystallization half-time of PLLA/PDLA components decreases; its spherulitic growth rate and Xc,SC increase as the mass fraction of PVDF increases from 0 to 0.5 in the presence of either a solidified or a molten PVDF phase. The HCs formed in primary crystallization of PLLA/PDLA components melt and recrystallize into SCs upon heating; the HC-to-SC melt reorganization is promoted after blending with PVDF. We proposed that the PVDF-promoted crystallization, SC formation, and HC-to-SC melt reorganization of PLLA/PDLA components in PLLA/PDLA/PVDF blends stem from the enhanced diffusion ability of PLLA and PDLA chains. PMID:27414064

  6. Preparation and Crystal Structure of Ordered and Disordered Lithium Nitride Dichloride, Li 5NCl 2

    NASA Astrophysics Data System (ADS)

    Marx, Rupert; Mayer, Hans-Michael

    1997-04-01

    A previosly unknown ordered low-temperature phase Li5NCl2-II has been obtained from the disordered high-temperature phase Li5NCl2-I by slow cooling (100°/h), while prolonged annealing at 400°C resulted in a decomposition to Li4NCl and LiCl. Neutron powder diffraction data were collected for both compounds and analyzed by the Rietveld method of profile refinement. Li5NCl2-II crystallizes in the hexagonal rhombohedral space groupRoverline3m,a=366.10 (3),c=2851.6 (3) pm with three formula units per unit cell. Its structure may be regarded as composed of lithium nitride-like [Li4N]+layers and rock-salt-like [LiCl2]-double-layers, stacked along the hexagonalcaxis. A redetermination of the Li2O-type structure of Li5NCl2-I indicates the presence of N-Cl short-range order.

  7. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods.

  8. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods. PMID:21701196

  9. Study of structural and ferromagnetic resonance properties of spinel lithium ferrite (LiFe5O8) single crystals

    NASA Astrophysics Data System (ADS)

    Pachauri, Neha; Khodadadi, Behrouz; Althammer, Matthias; Singh, Amit V.; Loukya, B.; Datta, Ranjan; Iliev, Milko; Bezmaternykh, Leonard; Gudim, Irina; Mewes, Tim; Gupta, Arunava

    2015-06-01

    The effect of B-site cation ordering on the room temperature structural and ferromagnetic resonance (FMR) properties of single crystal spinel lithium ferrite (LiFe5O8, LFO) have been investigated. A detailed microstructural analysis is done through X-ray diffraction, polarized Raman spectroscopy, and transmission electron microscopy (TEM) to examine the effect of post-annealing on the B-site cation ordering. The X-ray diffraction pattern of the as-grown crystal indicates a disordered state of the crystal. However, the annealed sample shows additional superlattice reflections corresponding to the ordered phase. This ordering is further confirmed by Raman spectra and TEM images, which reveal ordering of Li and Fe ions at the octahedral sites contrasting with the relatively high degree of octahedral site disorder in the as-grown crystal. To study the effect of B-site ordering on the magnetic properties and FMR linewidth, vibrating sample magnetometry and broadband FMR measurements have been performed for both the ordered and disordered phases of lithium ferrite. The value of saturation magnetization for both phases is ˜290 emu/cm3. A single mode FMR profile is observed for both phases with little distortion. The linewidth characteristics of the ordered and disordered phases of lithium ferrite phases are compared, and it is observed that the linewidth is independent of the cation ordering. Both the phases exhibit a low linewidth (˜26 Oe at 30 GHz) and the effective damping parameter for the as-grown and annealed samples is determined to be 0.0021 ± 0.0001.

  10. Luminescence spectroscopy from the vacuum ultra-violet to the visible for Er 3+ and Tm 3+ in complex fluoride crystals

    NASA Astrophysics Data System (ADS)

    Khaidukov, N. M.; Lam, S. K.; Lo, D.; Makhov, V. N.; Suetin, N. V.

    2002-05-01

    Spectra and decay kinetics of luminescence from several complex fluorides of alkali elements and yttrium or gadolinium doped with Er 3+ or Tm 3+ have been studied in the vacuum ultra-violet (VUV), ultra-violet (UV) and visible spectral ranges under excitation by the 157 nm radiation from a pulsed molecular F 2-laser. It has been found that yttrium crystals have intense VUV luminescence due to interconfiguration 5d-4f transitions in the rare earth ions. On the other hand, the 5d-4f luminescence from Er 3+ or Tm 3+ in gadolinium crystals is completely absent and the nonradiative decay as a result of cross-relaxation is the dominant decay channel from the 5d level of the doping rare earth ion in these crystals. This process leads to complete conversion of absorbed VUV radiation into the lower energy part of the spectrum. These gadolinium fluorides appear to be promising materials for VUV-excited phosphors with high-quantum efficiency.

  11. Test beam results with a sampling calorimeter of cerium fluoride scintillating crystals and tungsten absorber plates for calorimetry at the HL-LHC

    NASA Astrophysics Data System (ADS)

    Becker, R.; Dissertori, G.; Djambazov, L.; Donegà, M.; Dröge, M.; Haller, C.; Horisberger, U.; Lustermann, W.; Nessi-Tedaldi, F.; Quittnat, M.; Pandolfi, F.; Peruzzi, M.; Schönenberger, M.; Cavallari, F.; Dafinei, I.; Diemoz, M.; D`Imperio, G.; del Re, D.; Gelli, S.; Jorda Lope, C.; Meridiani, P.; Micheli, F.; Nuccetelli, M.; Organtini, G.; Paramatti, R.; Pellegrino, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Soffi, L.; Tabarelli de Fatis, T.; Martelli, A.; Monti, V.; Pastrone, N.; Trapani, P. P.; Candelise, V.; Della Ricca, G.

    2016-07-01

    A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (< 10 % /√{ E }). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors' forward regions during the high luminosity phase of LHC.

  12. Fluoride evaporation and crystallization behavior of CaF2-CaO-Al2O3-(TiO2) slag for electroslag remelting of Ti-containing steels

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-bin; Cho, Jung-wook; Zheng, Ding-li; Li, Jing

    2016-06-01

    To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2-CaO-Al2O3-(TiO2) slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite (CaTiO3) crystals instead of CaO crystals in the slag. The crystallization of perovskite (CaTiO3) occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

  13. Microstructure and defects probed by Raman spectroscopy in lithium niobate crystals and devices

    SciTech Connect

    Fontana, Marc D.; Bourson, Patrice

    2015-12-15

    Raman microprobe applied on LiNbO{sub 3} (LN) crystals and derived materials or devices is shown to be a tool to detect either local variations or changes of the whole structure. Position, width, or intensity of one Raman line can be used as markers of a structural change. Indeed, each Raman line can be assigned to a peculiar ionic motion and is differently sensitive to application of strain, temperature change, and electric field. Some vibrational modes are especially associated to the site of Li ion, or Nb ion, or still oxygen octahedron, so that they can be affected by the introduction of dopant ion on one or another site. Therefore, Raman Spectroscopy (RS) can be used as a site spectroscopy to describe the mechanism of doping incorporation in the LN lattice, allowing the optimization of some linear and non-linear optical properties according to the dopant concentration and substitution site. The composition or the content of non-stoichiometry related defects could be derived from the width of some lines. Any damage or local disorder can be detected by a line broadening. The quality or preservation of the structure after chemical treatment, or laser pulses, can be thus checked. The structure of ion-implanted or proton-exchanged wave-guides and periodically poled lithium niobate as well can be imaged from frequency shift or intensity change of some lines. RS is thus a useful way to control the structure of LN and/or to optimize the preparation parameters and its properties.

  14. Microstructure and defects probed by Raman spectroscopy in lithium niobate crystals and devices

    NASA Astrophysics Data System (ADS)

    Fontana, Marc D.; Bourson, Patrice

    2015-12-01

    Raman microprobe applied on LiNbO3 (LN) crystals and derived materials or devices is shown to be a tool to detect either local variations or changes of the whole structure. Position, width, or intensity of one Raman line can be used as markers of a structural change. Indeed, each Raman line can be assigned to a peculiar ionic motion and is differently sensitive to application of strain, temperature change, and electric field. Some vibrational modes are especially associated to the site of Li ion, or Nb ion, or still oxygen octahedron, so that they can be affected by the introduction of dopant ion on one or another site. Therefore, Raman Spectroscopy (RS) can be used as a site spectroscopy to describe the mechanism of doping incorporation in the LN lattice, allowing the optimization of some linear and non-linear optical properties according to the dopant concentration and substitution site. The composition or the content of non-stoichiometry related defects could be derived from the width of some lines. Any damage or local disorder can be detected by a line broadening. The quality or preservation of the structure after chemical treatment, or laser pulses, can be thus checked. The structure of ion-implanted or proton-exchanged wave-guides and periodically poled lithium niobate as well can be imaged from frequency shift or intensity change of some lines. RS is thus a useful way to control the structure of LN and/or to optimize the preparation parameters and its properties.

  15. Eurolaser. High power excimer laser: Optical crystals

    NASA Astrophysics Data System (ADS)

    Gaenswein, Bernhard

    1987-09-01

    The crystals used in excimer lasers because of their excellent optical properties in the ultra violet spectrum are described. The crystals are fluorides of the alkaline earth metals magnesium, calcium and barium and the alkaline fluorides of lithium and sodium. It is possible to grow optical monocrystals of these compounds up to weights of 15 kg with a diameter of 180 mm. Some problems develop in growing crystals larger than this. To do so greater plants and improved automatic temperature monitoring and regulation are required. Special tools are needed for handling such large and heavy monocrystals. Understanding of the interaction between laser radiation and crystal must be improved upon in order to meet all the requirements to be placed on optical components in the future.

  16. Optical constants and related electronic energy bands of lithium triborate crystal in the 6{endash}12-eV region

    SciTech Connect

    Chen, T.; Tao, R.; Rife, J.C.; Hunter, W.R.

    1998-01-01

    Reflectance of lithium triborate crystal in the 6{endash}12-eV region is measured with synchrotron radiation, and the principal values of optical constants are derived. Six absorption peaks are found in both X- and Y-polarized spectra. Among them the five transitions of the Y-polarized peaks and three of the X-polarized peaks are identified. The measurement suggests that the energy of the lowest conducting band 4A{sub 2} is 7.3 eV rather than 7.57 eV, as previously reported. {copyright} 1998 Optical Society of America

  17. Effects of crystallization temperature of poly(vinylidene fluoride) on crystal modification and phase transition of poly(butylene adipate) in their blends: a novel approach for polymorphic control.

    PubMed

    Yang, Jinjun; Pan, Pengju; Hua, Lei; Feng, Xin; Yue, Junjie; Ge, Yanhui; Inoue, Yoshio

    2012-02-01

    Effects of the isothermal crystallization temperatures of poly(vinylidene fluoride), T(IC,PVDF), on polymorphic crystalline structure, phase transition, fractional crystallization, and enzymatic degradation of poly(butylene adipate) (PBA) in crystalline/crystalline blends have been investigated. The crystal modifications of PBA can be regulated by T(IC,PVDF). Lower T(IC,PVDF) (e.g., 80 °C) facilitates the formation of PBA α crystals in both the isothermal and nonisothermal melt crystallizations and also favors the β-to-α phase transition of PBA upon annealing at elevated temperatures. This might be attributable to the decreased equilibrium melting temperature of PBA when T(IC,PVDF) is decreased. Higher T(IC,PVDF) is favorable for the fractional crystallization of PBA, which tends to segregate in the interlamellar regions of the PVDF matrix under these conditions. PBA shows faster enzymatic degradation in the blends with a lower T(IC,PVDF) than those with a higher T(IC,PVDF), attributable to the preferential formation of α crystals at a lower T(IC,PVDF). This study provides a new method to control the crystal modification and physical properties of polymorphic polymers in their blend systems.

  18. Study of beryllium and beryllium-lithium complexes in single-crystal silicon.

    NASA Technical Reports Server (NTRS)

    Crouch, R. K.; Robertson, J. B.; Gilmer, T. E., Jr.

    1972-01-01

    When beryllium is thermally diffused into silicon, it gives rise to acceptor levels 191 and 145 meV above the valence band. Quenching and annealing studies indicate that the 145-meV level is due to a more complex beryllium configuration than the 191-meV level. When lithium is thermally diffused into a beryllium-doped silicon sample, it produces two new acceptor levels at 106 and 81 meV. Quenching and annealing studies indicate that these new levels are due to lithium forming a complex with the defects responsible for the 191- and 145-meV beryllium levels, respectively. Electrical measurements imply that the lithium impurity ions are physically close to the beryllium impurity atoms. The ground state of the 106-meV beryllium-lithium level is split into two levels, presumably by internal strains. Tentative models are proposed to explain these results.

  19. Bulk crystal growth, optical, mechanical and ferroelectric properties of new semiorganic nonlinear optical and piezoelectric Lithium nitrate monohydrate oxalate single crystal

    NASA Astrophysics Data System (ADS)

    Dalal, Jyoti; Kumar, Binay

    2016-01-01

    New semiorganic nonlinear optical single crystals of Lithium nitrate oxalate monohydrate (LNO) were grown by slow evaporation solution technique. Single crystal X-ray diffraction study indicated that LNO crystal belongs to the triclinic system with space group P1. Various functional groups present in the material were identified by FTIR and Raman analysis. UV-vis study showed the high transparency of crystals with a wide band gap 5.01 eV. Various Optical constants i.e. Urbach energy (Eu), extinction coefficient (K), refractive index, optical conductivity, electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. A sharp emission peak was found at 438 nm in photoluminescence measurement, which revealed suitability of crystal for fabricating violet lasers. In dielectric studies, a peak has been observed at 33 °C which is due to ferroelectric to paraelectric phase transition. Piezoelectric charge coefficients (d33 = 9.2 pC/N and g33) have been calculated, which make it a suitable for piezoelectric devices applications. In ferroelectric studies, a saturated loop was found in which the values of coercive field and remnant polarization were found to be 2.18 kV/cm and 0.39 μC/cm2, respectively. Thermal behavior was studied by TGA and DSC studies. The relative SHG efficiency of LNO was found to be 1.2 times that of KDP crystal. In microhardness study, Meyer's index value was found to be 1.78 which revealed its soft nature. These optical, dielectric, piezoelectric, ferroelectric, mechanical and non-linear optical properties of grown crystal establish the usefulness of this material for optoelectronics, non-volatile memory and piezoelectric devices applications.

  20. A study of beryllium and beryllium-lithium complexes in single crystal silicon

    NASA Technical Reports Server (NTRS)

    Crouch, R. K.; Robertson, J. B.; Gilmer, T. E., Jr.

    1972-01-01

    When beryllium is thermally diffused into silicon, it gives rise to acceptor levels 191 MeV and 145 meV above the valence band. Quenching and annealing studies indicate that the 145-MeV level is due to a more complex beryllium configuration than the 191-MeV level. When lithium is thermally diffused into a beryllium-doped silicon sample, it produces two acceptor levels at 106 MeV and 81 MeV. Quenching and annealing studies indicate that these levels are due to lithium forming a complex with the defects responsible for the 191-MeV and 145-MeV beryllium levels, respectively. Electrical measurements imply that the lithium impurity ions are physically close to the beryllium impurity atoms. The ground state of the 106-MeV beryllium level is split into two levels, presumably by internal strains. Tentative models are proposed.

  1. Nano-domains and related phenomena in congruent lithium tantalate single crystals studied by scanning nonlinear dielectric microscopy.

    PubMed

    Cho, Yasuo

    2014-08-01

    Nanodomains and their related phenomena in congruent lithium tantalate (CLT) single crystals are studied using scanning nonlinear dielectric microscopy (SNDM). We carried out two specific investigations: super higher order nonlinear dielectric spectroscopy studies on thick multi-domain congruent CLT single crystals and electrical conduction in nanodomains in thin CLT single crystals. First, without using a special sharp tip, we achieve improved lateral resolution in SNDM through the measurement of super higher order nonlinearity up to the fourth order. We also found a marked enhancement of nonlinear dielectric constants when the applied tip-sample voltage exceeded a particular threshold value. This is due to domain nucleation activated by a huge electric field under the tip. Low frequencies (less than a few hundred hertz) do not enhance nonlinearity. An effectively lower electric field caused by ion conduction in the sample under the tip is a possible reason for the frequency-dependent characteristics of the enhanced nonlinearity for the applied voltage. Finally, electrical current flow behavior was investigated for nanodomains formed in a thin CLT single-crystal plate. When the nanodomains are relatively large, with diameters of about 100 nm, current flow is detected along the domain wall. However, when the nanodomains were about 40 nm or smaller in size, current flowed through the entire nanodomain. Schottky-like rectifying behavior was observed. A clear temperature dependence of the current is found, indicating that the conduction mechanism for nanodomains in CLT may involve thermally activated carrier hopping.

  2. Bottled Water and Fluoride

    MedlinePlus

    ... Fluoridation Journal Articles for Community Water Fluoridation Bottled Water Recommend on Facebook Tweet Share Compartir Consumers drink ... questions about bottled water and fluoride. Does bottled water contain fluoride? Bottled water products may contain fluoride, ...

  3. Crystallinity and solubility behavior of iron-containing fluoridated hydroxyapatites.

    PubMed

    Okazaki, M; Takahashi, J; Kimura, H

    1986-09-01

    Iron-containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80 degrees C and pH 7.4 using FeCl2 X nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites at low fluoride content.

  4. Effect of different conventional melt quenching technique on purity of lithium niobate (LiNbO3) nano crystal phase formed in lithium borate glass

    NASA Astrophysics Data System (ADS)

    Kashif, Ismail; Soliman, Ashia A.; Sakr, Elham M.; Ratep, Asmaa

    2012-01-01

    The glass system (45Li2O + 45B2O3 + 10Nb2O5) was fabricated by the conventional melt quenching technique poured in water, at air, between two hot plates and droplets at the cooled surface. The glass and glass ceramics were studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). The as quenched samples poured in water and between two hot plates were amorphous. The samples poured at air and on cooled surface were crystalline as established via X-ray powder diffraction (XRD) studies. Differential thermal analysis was measured. The glass transition temperature (Tg) and the crystallization temperatures were calculated. Lithium niobate (LiNbO3) was the main phase in glass ceramic poured at air, droplets at the cooled surface and the heat treated glass sample at 500, 540 and 580 °C in addition to traces from LiNb3O8. Crystallite size of the main phases determined from the X-ray diffraction peaks is in the range of <100 nm. The fraction of crystalline (LiNbO3) phase decreases with increase in the heat treatment temperature.

  5. Enhanced electroactive and mechanical properties of poly(vinylidene fluoride) by controlling crystallization and interfacial interactions with low loading polydopamine coated BaTiO₃.

    PubMed

    Jia, Nan; Xing, Qian; Liu, Xu; Sun, Jing; Xia, Guangmei; Huang, Wei; Song, Rui

    2015-09-01

    Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer and the polar β-phase of PVDF shows superb electroactive properties. In order to enhance the β-phase of PVDF, extreme low content of BaTiO3 nanoparticles (BT-NPs) coated with polydopamine (Pdop) were incorporated into PVDF matrix by solution casting. The β-phase of the resulting PVDF nanocomposites film was dramatically increased and the d33 value reached 34.3±0.4 pCN(-1). It is found that the Pdop layer could improve the dispersibility and stability of the BT NPs in solution and endow the BT NPs good dispersity in the PVDF matrix. Moreover, the interfacial interaction between PVDF chains and the surface of BT-Pdop nanoparticles (BT-Pdop NPs) were revealed, in which the CF2 groups on PVDF could interact with the electron-rich plane of aromatic ring of Pdop moiety. This interaction, led to the increase of the crystallization activation energy as derived from the DSC nonisothermal crystallization measurement. The α-β crystal transformation, organization of interfacial interactions as well as the prevention of agglomeration of BT-NPs confer the improvement of mechanical and thermal properties of PVDF, such as toughness, tensile strength, elongation at break, and thermal conductivity. PMID:25985420

  6. Phase selection during the crystallization of metal-organic frameworks; thermodynamic and kinetic factors in the lithium tartrate system.

    PubMed

    Yeung, Hamish Hei-Man; Cheetham, Anthony Kevin

    2014-01-01

    We report the phase behaviour of chiral, racemic and meso-lithium tartrate frameworks, which was examined as a function of solvent system, temperature and ligand isomer. Through our comprehensive investigation of this system of 14 diverse phases, we have gained detailed insight into the effect of synthesis conditions on product structure, and elucidated the thermodynamic and kinetic factors involved in phase selection. Reactions in ethanol between lithium acetate and chiral, racemic and meso-tartaric acids give rise to anhydrous kinetic products; polymorphs with higher entropy tend to appear at high temperatures. Reactions at room temperature in water-ethanol mixtures give rise to hydrated kinetic products, including two new crystal structures, [Li2(D,L-tartrate)(H2O)2]n in P1 and [Li2(meso-tartrate)(H2O)(0.5)]n in C222(1), whose structures are contrasted with known anhydrous products. Reactions at elevated temperatures in water-ethanol mixtures result in the formation of low enthalpy, anhydrous products and, furthermore, the global minimum energy structure appears at high temperatures in all cases owing to in situ ligand isomerization.

  7. Crystal modification of iron oxide scale by potassium addition and its application to lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Jung, Dong-Won; Han, Sang-Wook; Kong, Byung-Seon; Oh, Eun-Suok

    2013-11-01

    This paper proposes a valuable method to reuse the iron oxide scale (IOS) often produced in the steel industry as an anode active material in lithium-ion batteries (LIBs). The IOS samples are prepared via quenching of carbon steel and simple oxidation at a high temperature with or without sequential treatment by potassium hydroxide. Morphological and physical characterizations confirm the formation of a lamellar structure of orthorhombic KFeO2 with a high degree of crystallinity in the potassium-added IOSs. Additionally, the potassium addition decreases the particle size of the crystals and increases the d-spacing between crystal layers. Electrochemical performance tests show that the discharge capacities of the IOS samples monotonically increased with increasing number of charge/discharge cycles regardless of the existence of potassium. In addition, the rate of increase is larger in the potassium-added IOS samples containing the lamellar KFeO2 structure. Consequently, after prolonged cycling (more than 500 cycles), the potassium-added IOS sample retains a discharge capacity of 1020 mAh g-1 with good cycling stability, while the IOS quenched sample only exhibits a capacity of 956 mAh g-1. This result is attributed to the unique structure of the KFeO2 crystals formed in the potassium-added IOS particles.

  8. Lithium ion diffusion in Li β-alumina single crystals measured by pulsed field gradient NMR spectroscopy

    SciTech Connect

    Chowdhury, Mohammed Tareque Takekawa, Reiji; Iwai, Yoshiki; Kuwata, Naoaki; Kawamura, Junichi

    2014-03-28

    The lithium ion diffusion coefficient of a 93% Li β-alumina single crystal was measured for the first time using pulsed field gradient (PFG) NMR spectroscopy with two different crystal orientations. The diffusion coefficient was found to be 1.2 × 10{sup −11} m{sup 2}/s in the direction perpendicular to the c axis at room temperature. The Li ion diffusion coefficient along the c axis direction was found to be very small (6.4 × 10{sup −13} m{sup 2}/s at 333 K), which suggests that the macroscopic diffusion of the Li ion in the β-alumina crystal is mainly two-dimensional. The diffusion coefficient for the same sample was also estimated using NMR line narrowing data and impedance measurements. The impedance data show reasonable agreement with PFG-NMR data, while the line narrowing measurements provided a lower value for the diffusion coefficient. Line narrowing measurements also provided a relatively low value for the activation energy and pre-exponential factor. The temperature dependent diffusion coefficient was obtained in the temperature range 297–333 K by PFG-NMR, from which the activation energy for diffusion of the Li ion was estimated. The activation energy obtained by PFG-NMR was smaller than that obtained by impedance measurements, which suggests that thermally activated defect formation energy exists for 93% Li β-alumina single crystals. The diffusion time dependence of the diffusion coefficient was observed for the Li ion in the 93% Li β-alumina single crystal by means of PFG-NMR experiments. Motion of Li ion in fractal dimension might be a possible explanation for the observed diffusion time dependence of the diffusion coefficient in the 93% Li β–alumina system.

  9. Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

    NASA Astrophysics Data System (ADS)

    Tao, Chen; Rong, Shu; Ye, Ge; Zhuo, Chen

    2016-01-01

    We present the numerical results for the optimization of the pump-to-idler conversion efficiencies of nanosecond idler wavelength tunable cascaded optical parametric oscillators (OPO) in different wavelength tuning ranges, where the primary signals from the OPO process are recycled to enhance the pump-to-idler conversion efficiencies via the simultaneous difference frequency generation (DFG) process by monolithic aperiodically poled, magnesium oxide doped lithium niobate (APMgLN) crystals. The APMgLN crystals are designed with different chirp parameters for the DFG process to broaden their thermal acceptance bandwidths to different extents. The idler wavelength tuning of the cascaded OPO is realized by changing the temperature of the designed APMgLN crystal and the cascaded oscillation is achieved in a single pump pass singly resonant linear cavity. The pump-to-idler conversion efficiencies with respect to the pump pulse duration and ratio of OPO coefficient to DFG coefficient are calculated by numerically solving the coupled wave equations. The optimal working conditions of the tunable cascaded OPOs pumped by pulses with energies of 350 μJ and 700 μJ are compared to obtain the general rules of optimization. It is concluded that the optimization becomes the interplay between the ratio of OPO coefficient to DFG coefficient and the pump pulse duration when the idler wavelength tuning range and the pump pulse energy are fixed. Besides, higher pump pulse energy is beneficial for reaching higher optimal pump-to-idler conversion efficiency as long as the APMgLN crystal is optimized according to this pump condition. To the best of our knowledge, this is the first numerical analysis of idler wavelength tunable cascaded OPOs based on chirp-assisted APMgLN crystals. Project supported by the National Natural Science Foundation of China (Grant No. 61505236), the Innovation Program of Shanghai Institute of Technical Physics, China (Grant No. CX-2), and the Program of Shanghai

  10. Laser-writing inside uniaxially birefringent crystals: fine morphology of ultrashort pulse-induced changes in lithium niobate.

    PubMed

    Karpinski, P; Shvedov, V; Krolikowski, W; Hnatovsky, C

    2016-04-01

    This work presents a detailed analysis of the morphology of femtosecond laser-induced changes in bulk lithium niobate (LiNbO3) - one of the most common host materials in photonics - using second-harmonic generation microscopy and scanning electron microscopy. It is shown that focused linearly polarized near-infrared pulses can produce two or three distinct axially separated regions of modified material, depending on whether the pulse propagation is along or perpendicular to the optical axis. When laser writing in LiNbO3 is conducted in multi-shot irradiation mode and the focused light intensity is kept near the bulk damage threshold, periodic planar nanostructures aligned perpendicular to the laser polarization are produced inside the focal volume. These results provide a new perspective to laser writing in crystalline materials, including the fabrication of passive and active waveguides, photonic crystals, and optical data storage devices. PMID:27137036

  11. Predicted performance of the lithium scattering and graphite crystal polarimeter for the Spectrum-X-Gamma mission

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.; Elsner, R. F.; Novick, R.; Kaaret, P.; Silver, E.

    1991-01-01

    X-ray scattering from a lithium disk and Bragg reflection from a mosaic graphite crystal can be exploited to measure the linear polarization of radiation emitted from cosmic X-ray sources. The sensitivity is greatly enhanced if these polarimeters are placed at the focus of an X-ray telescope. Such devices form two of the three components of the Stellar X-Ray Polarimeter experiment scheduled to fly on the Spectrum-X-Gamma mission. The experiment will reside at the focus of one of the SODART X-ray telescopes. The expected on-axis performance of these two components of the Stellar X-Ray Polarimeter experiment based on detailed Monte-Carlo simulation is described. Various systematic effects, both external and internal to the experiment, that must be considered in order to properly design and utilize the experiment are also discussed.

  12. The Effect of Chain Structures on the Crystallization Behavior and Membrane Formation of Poly(Vinylidene Fluoride) Copolymers

    PubMed Central

    Ma, Wenzhong; Yuan, Haoge; Wang, Xiaolin

    2014-01-01

    The crystallization behaviors of two copolymers of PVDF were studied, and the effect of copolymerized chains on the crystallization behavior was investigated. The results indicated that both copolymers had a lowered crystallization temperature and crystallinity. The crystallization rate was improved by the copolymer with symmetrical units in PVDF chains, but hindered by asymmetrical units, compared with the neat PVDF. The symmetrical units in PVDF chains favored the β-crystals with fiber-like structures. According to the solubility parameter rule, methyl salicylate (MS) can be chosen as a diluent for PVDF copolymers. Both diluted systems had liquid-liquid (L-L) regions in the phase diagrams, which was due to the lowered crystallization temperature. PMID:24957175

  13. Crystallization kinetics of lithium niobate glass: determination of the Johnson-Mehl-Avrami-Kolmogorov parameters.

    PubMed

    Choi, H W; Kim, Y H; Rim, Y H; Yang, Y S

    2013-06-28

    The formation of crystalline LiNbO3 (LN) from LN glass has been studied by means of differential scanning calorimetry and in situ synchrotron X-ray diffraction. The LN glass with no glass former was prepared by the polymerized complex method. The isothermal kinetics of the crystallization process is described using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and the Avrami exponent n is found to be ~2.0, indicating that the crystallization mechanism is diffusion-controlled growth with a decreasing nucleation rate. The effective activation energy of crystallization calculated from isothermal measurements is 6.51 eV. It is found that the LN glass directly transforms into a rhombohedral LN crystal without any intermediate crystalline phase and most crystal grains are confined within the size of ~40 nm irrespective of different isothermal temperatures. Application of JMAK theory to the non-isothermal thermoanalytical study of crystallization of LN glass is discussed.

  14. Functionalized guanidinium chloride based colourimetric sensors for fluoride and acetate: single crystal X-ray structural evidence of -NH deprotonation and complexation.

    PubMed

    Bose, Purnandhu; Ahamed, B Nisar; Ghosh, Pradyut

    2011-03-21

    A series of new symmetrically functionalized guanidinium chlorides (S1-S10) are synthesized in good yields and their sensing ability toward anions is studied in MeCN-DMF (24 : 1) (v/v). The absorption bands of these molecules in the presence of anions are tuned by varying the functional groups attached to the guanidinium moiety (which resembles urea) with respect to (i) aromaticity (S1-S4), (ii) electron induction effect (S1, S5-S9), (iii) positional isomeric effect (S7-S9), (iv) indole functionality (S10) of the conjugated aryl units. Anions that are above Cl(-) in the Hofmeister series (F(-), AcO(-), H(2)PO(4)(-)) are eligible as an analyte in this series of molecules whereas less basic anions than Cl(-) do not cause any interference. Thus, this series of molecules are suitable for the detection of anions in the narrow window of the Hofmeister series. Out of all the anions, only fluoride causes vivid colour changes from yellow to red to reddish orange and finally to blue, irrespective of the increasing aromaticity, induction and positional isomeric effect of the substituent that is attached to the guanidinium moiety. Interestingly, S9 has shown the ability to sense distinctly both F(-) and AcO(-) colourimetrically. Further S10, a sensor attached with indole functionality shows selective sensing of F(-) colourimetrically with a NIR signature at ∼930 nm though both these outputs are very unstable in nature. Stability constants for complex formation of S1-S10 (except S5) with F(-), AcO(-) are calculated by UV-vis titration experiments. Finally single crystal X-ray structural studies on the species 1 formed upon treating S6 with sodium fluoride confirms -NH deprotonation, whereas the reaction of S6 and S2 with sodium benzoate shows 1:1 host:guest binding that results in complexes 2 and 3 respectively.

  15. Tip-induced domain growth on the non-polar cuts of lithium niobate single-crystals

    SciTech Connect

    Alikin, D. O.; Turygin, A. P.; Lobov, A. I.; Shur, V. Ya.; Ievlev, A. V.; Kalinin, S. V.

    2015-05-04

    Currently, ferroelectric materials with designed domain structures are considered as a perspective material for new generation of photonic, data storage, and data processing devices. Application of external electric field is the most convenient way of the domain structure formation. Lots of papers are devoted to the investigation of domain kinetics on polar surface of crystals while the forward growth remains one of the most mysterious stages due to lack of experimental methods allowing to study it. Here, we performed tip-induced polarization reversal on X- and Y-non-polar cuts in single-crystal of congruent lithium niobate which allows us to study the forward growth with high spatial resolution. The revealed difference in the shape and length of domains induced on X- and Y-cuts is beyond previously developed theoretical approaches used for the theoretical consideration of the domains growth at non-polar ferroelectric surfaces. To explain experimental results, we used kinetic approach with anisotropy of screening efficiency along different crystallographic directions.

  16. Electrical conductivity and pyroelectricity of lithium-potassium sulphate single crystal in the temperature range 300-950 K

    NASA Astrophysics Data System (ADS)

    Abu El-Fadl, A.; Gaffar, M. A.; Omar, M. H.

    1999-09-01

    The DC electrical conductivity ( σ) along the a- and c-axes and the pyroelectric coefficient ( p) along the pyroelectric c-axis of lithium-potassium sulphate (LKS) single crystal are measured in the temperature range 300-950 K. The measurements of σ show anomalous behaviour at the transition point around 705 K. The σ- T relationship reveals an activation energy of conduction along the c-axis of 0.85 eV above and 0.37 eV below the transition temperature, respectively. The effect of thermal recycling on the electric conduction is discussed. A maximum signal at about 720 K and a variation in the sign of p at about 704 K have been observed. The phase transition reported in the literature at 333 K was not confirmed by our measurements. The current density ( J) is measured as a function of the applied electric field ( E) below and above the phase transition temperature along the c- and a-axes in order to estimate the type of conduction dominated and the effect of E upon the conductivity measurements of this crystal.

  17. Determination of trace elements in lithium niobate crystals by solid sampling and solution-based spectrometry methods.

    PubMed

    Bencs, László; György, Krisztina; Kardos, Márta; Osán, János; Alföldy, Bálint; Varga, Imre; Ajtony, Zsolt; Szoboszlai, Norbert; Stefánka, Zsolt; Széles, Eva; Kovács, László

    2012-05-13

    Solid sampling (SS) graphite furnace atomic absorption spectrometry (GFAAS) and solution-based (SB) methods of GFAAS, flame atomic absorption spectrometry (FAAS), inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) were elaborated and/or optimized for the determination of Cr, Fe and Mn trace elements used as dopants in lithium niobate optical crystals. The calibration of the SS-GFAAS analysis was possible with the application of the three-point-estimation standard addition method, while the SB methods were mostly calibrated against matrix-matched and/or acidic standards. Spectral and non-spectral interferences were studied in SB-GFAAS after digestion of the samples. The SS-GFAAS method required the use of less sensitive spectral lines of the analytes and a higher internal furnace gas (Ar) flow rate to decrease the sensitivity for crystal samples of higher (doped) analyte content. The chemical forms of the matrix produced at various stages of the graphite furnace heating cycle, dispensed either as a solid sample or a solution (after digestion), were studied by means of the X-ray near-edge absorption structure (XANES). These results revealed that the solid matrix vaporized/deposited in the graphite furnace is mostly present in the metallic form, while the dry residue from the solution form mostly vaporized/deposited as the oxide of niobium. PMID:22541007

  18. Functionalization of borate networks by the incorporation of fluoride: Syntheses, crystal structures; and nonlinear optical properties of novel actinide fluoroborates

    SciTech Connect

    Wang, Shuao; Alekseev, Evgeny V.; Diwu, Juan; Miller, Hannah M.; Oliver, Allen G.; Liu, Guokui; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.

    2011-06-14

    The boric acid flux reactions of uranyl nitrate with sodium, potassium, rubidium, or thallium fluoride result in the formation of a novel family of uranyl(VI) fluoroborate materials. These compounds are Na[(UO₂)B₅O₈(OH)F]·H₂O (NaUBOF-1), K[(UO₂)B₅O₈(OH)F] (KUBOF-1), K₁₁[(UO₂)₆B₂₄O₃₆F₂₂)](H₂BO₃) (KUBOF-2), Rb[(UO₂)B₅O₈(OH)F] (RbUBOF-1), and Tl[(UO₂)B₅O₈(OH)F] (TlUBOF-1). A new neptunium(VI) fluoroborate that is isotypic with NaUBOF-1, Na[(NpO₂)B₅O₈(OH)F]·H₂O (NaNpBOF-1), was synthesized via the boric acid flux reaction of neptunium(VI) nitrate with sodium fluoride. These new actinide fluoroborates share a common structural motif consisting of a linear actinyl (U(Np)O₂2+) cation surrounded by BO₃ triangles and BO₄ tetrahedra to create an U(Np)O₈ hexagonal bipyramidal environment around uranium or neptunium. The borate anions bridge between actinyl units to create layers. B–F bonds were formed during the reactions to yield BO₃F tetrahedral units. The BO3F tetrahedra and additional BO₃ triangles extend from the actinyl polyborate layers and are directed approximately perpendicular to the layers. A novel actinyl borate layered topology was found in K₁₁[(UO₂)₆B₂₄O₃₆F₂₂)](H₂BO₃) (KUBOF-2). Except for K[(UO₂)B₅O₈(OH)F] (KUBOF-1) and K₁₁[(UO₂)₆B₂₄O₃₆F₂₂)](H₂BO₃) (KUBOF-2), all of the other actinide fluoroborate phases adopt noncentrosymmetric space groups. Tl[(UO₂)B₅O₈(OH)F] (TlUBOF-1), which can be obtained as a pure phase, displays second-harmonic generation of 532-nm light from 1064-nm light.

  19. Lithium batteries. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Cavagnaro, D. M.

    1980-07-01

    Federally funded research on design, development, components, testing corrosion, electrolytes, sealing, hazards of lithium cells are presented. Batteries studied include lithium organic cells, lithium sulfur cells, lithium water air cells, and lithium nickel fluoride cells. Applications cover use in spacecraft, electric vehicles, off peak energy storage, and forklift trucks. This updated bibliography contains 151 citations, 57 of which are new entries to the previous edition.

  20. Investigations on synthesis, growth, electrical and defect studies of lithium selenoindate single crystals

    NASA Astrophysics Data System (ADS)

    Vijayakumar, P.; Magesh, M.; Arunkumar, A.; Anandha Babu, G.; Ramasamy, P.; Abhaya, S.

    2014-02-01

    LiInSe2 polycrystalline material was successfully synthesized from melt and temperature oscillation method (MTOM). The crystalline phase was confirmed by powder X-ray diffraction pattern. Crack free LiInSe2 single crystal of size 12 mm diameter and 32 mm length was grown using two zone tubular resistive heated furnace by modified vertical Bridgman-Stockbarger method with steady ampoule rotation. The grown LiInSe2 crystal was subjected to single crystal XRD, inductively coupled plasma-optical emission spectroscopy (ICP-OES), positron annihilation spectroscopy (PAS), Hall effect and dielectric measurements. Single crystal XRD measurement confirms the orthorhombic crystal system. ICP-OES analysis gives the crystal composition as Li0.81In1.01Se2.18. The average lifetime 278.03 ps in PAS measurements corresponds to vacancy clusters present in LiInSe2 crystal. Hall effect measurement confirms the n-type semiconductor nature. The dielectric permittivity and dielectric loss were obtained to be 9.8 and 0.108 respectively by capacitance measurements at room temperature for the frequency of 2 MHz.

  1. Periodic domain inversion in x-cut single-crystal lithium niobate thin film

    NASA Astrophysics Data System (ADS)

    Mackwitz, P.; Rüsing, M.; Berth, G.; Widhalm, A.; Müller, K.; Zrenner, A.

    2016-04-01

    We report the fabrication of periodically poled domain patterns in x-cut lithium niobate thin-film. Here, thin films on insulator have drawn particular attention due to their intrinsic waveguiding properties offering high mode confinement and smaller devices compared to in-diffused waveguides in bulk material. In contrast to z-cut thin film lithium niobate, the x-cut geometry does not require back electrodes for poling. Further, the x-cut geometry grants direct access to the largest nonlinear and electro-optical tensor element, which overall promises smaller devices. The domain inversion was realized via electric field poling utilizing deposited aluminum top electrodes on a stack of LN thin film/SiO2 layer/Bulk LN, which were patterned by optical lithography. The periodic domain inversion was verified by non-invasive confocal second harmonic microscopy. Our results show domain patterns in accordance to the electrode mask layout. The second harmonic signatures can be interpreted in terms of spatially, overlapping domain filaments which start their growth on the +z side.

  2. Structure, ion transport, and relaxation dynamics of polyethylene oxide/poly (vinylidene fluoride co-hexafluoropropylene)—lithium bis(trifluoromethane sulfonyl) imide blend polymer electrolyte embedded with ionic liquid

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, A.

    2016-03-01

    We have studied structure, ion transport, and relaxation dynamics in polyethylene oxide/poly (vinylidene fluoride-hexafluoropropylene)-lithium bis(trifluoromethane)sulfonimide blend polymer electrolytes embedded with 1-propyl-3-methyleimidazoliuum bis(trifluromethyle-sulfonyl)imide ionic liquid. Structural property and ion-polymer interaction of polymer electrolytes have been studied using X-ray diffraction and Raman spectroscopy. The addition of ionic liquid decreases glass transition temperature and reduces crystalline phase in the polymer matrix. It is also observed that surface becomes smooth with increase of ionic liquid content. The temperature dependence of the Li ion conductivity follows Vogel-Tammann-Fulcher type behaviour when a sufficient amount of ionic liquid is added to polymer matrix. The electric modulus has been studied using Havriliak-Negami function for the understanding of ion dynamics. The modulus data have been analyzed using non-exponential Kohlrausch-Williams-Watts function. It is observed that the non-exponential parameter β is quite lower than unity, suggesting existence of a non-exponential relaxation. The temperature dependence of the relaxation time also follows Vogel-Tammann-Fulcher relation for compositions with higher ionic liquid content.

  3. Molecular packing and magnetic properties of lithium naphthalocyanine crystals: hollow channels enabling permeability and paramagnetic sensitivity to molecular oxygen.

    PubMed

    Pandian, Ramasamy P; Dolgos, Michelle; Marginean, Camelia; Woodward, Patrick M; Hammel, P Chris; Manoharan, Periakaruppan T; Kuppusamy, Periannan

    2009-01-01

    The synthesis, structural framework, magnetic and oxygen-sensing properties of a lithium naphthalocyanine (LiNc) radical probe are presented. LiNc was synthesized in the form of a microcrystalline powder using a chemical method and characterized by electron paramagnetic resonance (EPR) spectroscopy, magnetic susceptibility, powder X-ray diffraction analysis, and mass spectrometry. X-Ray powder diffraction studies revealed a structural framework that possesses long, hollow channels running parallel to the packing direction. The channels measured approximately 5.0 × 5.4 Å(2) in the two-dimensional plane perpendicular to the length of the channel, enabling diffusion of oxygen molecules (2.9 × 3.9 Å(2)) through the channel. The powdered LiNc exhibited a single, sharp EPR line under anoxic conditions, with a peak-to-peak linewidth of 630 mG at room temperature. The linewidth was sensitive to surrounding molecular oxygen, showing a linear increase in pO(2) with an oxygen sensitivity of 31.2 mG per mmHg. The LiNc microcrystals can be further prepared as nano-sized crystals without the loss of its high oxygen-sensing properties. The thermal variation of the magnetic properties of LiNc, such as the EPR linewidth, EPR intensity and magnetic susceptibility revealed the existence of two different temperature regimes of magnetic coupling and hence differing columnar packing, both being one-dimensional antiferromagnetic chains but with differing magnitudes of exchange coupling constants. At a temperature of ∼50 K, LiNc crystals undergo a reversible phase transition. The high degree of oxygen-sensitivity of micro- and nano-sized crystals of LiNc, combined with excellent stability, should enable precise and accurate measurements of oxygen concentration in biological systems using EPR spectroscopy.

  4. Deformation, Stress Relaxation, and Crystallization of Lithium Silicate Glass Fibers Below the Glass Transition Temperature

    NASA Technical Reports Server (NTRS)

    Ray, Chandra S.; Brow, Richard K.; Kim, Cheol W.; Reis, Signo T.

    2004-01-01

    The deformation and crystallization of Li(sub 2)O (center dot) 2SiO2 and Li(sub 2)O (center dot) 1.6SiO2 glass fibers subjected to a bending stress were measured as a function of time over the temperature range -50 to -150 C below the glass transition temperature (Tg). The glass fibers can be permanently deformed at temperatures about 100 C below T (sub)g, and they crystallize significantly at temperatures close to, but below T,, about 150 C lower than the onset temperature for crystallization for these glasses in the no-stress condition. The crystallization was found to occur only on the surface of the glass fibers with no detectable difference in the extent of crystallization in tensile and compressive stress regions. The relaxation mechanism for fiber deformation can be best described by a stretched exponential (Kohlrausch-Williams-Watt (KWW) approximation), rather than a single exponential model.The activation energy for stress relaxation, Es, for the glass fibers ranges between 175 and 195 kJ/mol, which is considerably smaller than the activation energy for viscous flow, E, (about 400 kJ/mol) near T, for these glasses at normal, stress-free condition. It is suspected that a viscosity relaxation mechanism could be responsible for permanent deformation and crystallization of the glass fibers below T,

  5. Study on the Photorefractive Properties of Sc, in Co-Doped Lithium Niobate Crystals

    NASA Astrophysics Data System (ADS)

    Xu, Zhaopeng; Xu, Shiwen; Xu, Yuheng; Wang, Rui

    The Sc:In:LiNbO3 crystals co-doped with 0.5 mol% Sc2O3 and 0, 0.5, 0.75 and 1 mol% In2O3 were grown by the Czochralski method. The structure of the crystals was measured by infrared spectra. The mechanism of the shift of OH- absorption peak was investigated. The photo-damage resistance ability of Sc:In:LiNbO3 crystals was observed by the straightly observing transmission facula distortion method. The Sc:In:LiNbO3 waveguide substrates were fabricated by the proton exchange technique using benzoic acid as the proton source. The photo-damage thresholds of these y-cut waveguide substrates were measured by the m-line method. The results measured by the two methods above all show that the photo-damage resistance ability of Sc:In:LiNbO3 crystals increases two orders of magnitude in comparison with that of pure LiNbO3 crystals. The mechanism of the enhancement of the photo-damage resistance ability of Sc:In:LiNbO3 crystals is discussed by Li-vacancy model.

  6. Impact of crystal structure singularity on transport and electrochemical properties of Lix(LiyFezV1-y-z)O2 — electrode material for lithium batteries

    NASA Astrophysics Data System (ADS)

    Gędziorowski, Bartłomiej; Tobola, Janusz; Braun, Artur; Molenda, Janina

    2016-07-01

    Lithium vanadium oxide (LiVO2) and its substituted derivatives are a distinctive group of materials that may act both, as cathode and anode materials for Li-ion batteries. This paper presents influence of crystal structure singularity of Li(LiyFezV1-y-z)O2 (y=0, 0.03, 0.07, z=0, 0.05, 0.1) on transport and electrochemical properties of the compounds.

  7. A study of the piezoelectric resonance in metal organic NLO single crystals: Sodium D-isoascorbate monohydrate and Lithium L-ascorbate dihydrate

    NASA Astrophysics Data System (ADS)

    Saripalli, Ravi Kiran; Raghavendra Rao, K.; Sanath Kumar, R.; Bhat, H. L.; Elizabeth, Suja

    2016-05-01

    Large single crystals of Sodium D-isoacsorbate monohydrate and Lithium L-ascorbate dehydrate were grown using solution growth technique. Dielectric constant and dielectric loss were monitored as a function of frequency at different temperatures. These are typically characterized by strong resonance peaks. The piezoelectric coefficients d31, elastic coefficient (S11) and electromechanical coupling coefficient (k31) were estimated by resonance-antiresonance method. The temperature dependence of the resonance-peaks frequencies was studied.

  8. Growth of hollow nickel fluoride whiskers

    SciTech Connect

    Petrov, S. V.; Orekhov, Yu. F.; Fedorov, P. P.

    2009-07-15

    Hollow nickel fluoride whiskers have been obtained by condensation from the vapor phase onto a platinum substrate in a flow of hydrogen fluoride. Crystals up to 5 mm in length have a square cross section with a 300 {+-} 30-{mu}m side. The wall thickness is 85 {+-} 20 {mu}m.

  9. Theoretical exploration of various lithium peroxide crystal structures in a Li-air battery

    DOE PAGES

    Lau, Kah; Qiu, Dantong; Luo, Xiangyi; Greeley, Jeffrey; Curtiss, Larry; Lu, Jun; Amine, Khalil

    2015-01-14

    We describe a series of metastable Li₂O₂ crystal structures involving different orientations and displacements of the O₂²⁻ peroxy ions based on the known Li₂O₂ crystal structure. Within the vicinity of the chemical potential ΔG ~ 0.20 eV/Li from the thermodynamic ground state of the Li₂O₂ crystal structure (i.e., Föppl structure), all of these newly found metastable Li₂O₂ crystal structures are found to be insulating and high-k materials, and they have a common unique signature of an O₂²⁻ O-O vibration mode (ω ~ 799–865 cm⁻¹), which is in the range of that commonly observed in Li-air battery experiments, regardless of themore » random O₂²⁻ orientations and the symmetry in the crystal lattice. From XRD patterns analysis, the commercially available Li₂O₂ powder is confirmed to be the thermodynamic ground state Föppl-like structure. However, for Li₂O₂ compounds that are grown electrochemically under the environment of Li-O₂ cells, we found that the XRD patterns alone are not sufficient for structural identification of these metastable Li₂O₂ crystalline phases due to the poor crystallinity of the sample. In addition, the commonly known Raman signal of O₂²⁻ vibration mode is also found to be insufficient to validate the possible existence of these newly predicted Li₂O₂ crystal structures, as all of them similarly share the similar O₂²⁻ vibration mode. However considering that the discharge voltage in most Li-O₂ cells are typically several tenths of an eV below the thermodynamic equilibrium for the formation of ground state Föppl structure, the formation of these metastable Li₂O₂ crystal structures appears to be thermodynamically feasible.« less

  10. Theoretical exploration of various lithium peroxide crystal structures in a Li-air battery

    SciTech Connect

    Lau, Kah; Qiu, Dantong; Luo, Xiangyi; Greeley, Jeffrey; Curtiss, Larry; Lu, Jun; Amine, Khalil

    2015-01-14

    We describe a series of metastable Li₂O₂ crystal structures involving different orientations and displacements of the O₂²⁻ peroxy ions based on the known Li₂O₂ crystal structure. Within the vicinity of the chemical potential ΔG ~ 0.20 eV/Li from the thermodynamic ground state of the Li₂O₂ crystal structure (i.e., Föppl structure), all of these newly found metastable Li₂O₂ crystal structures are found to be insulating and high-k materials, and they have a common unique signature of an O₂²⁻ O-O vibration mode (ω ~ 799–865 cm⁻¹), which is in the range of that commonly observed in Li-air battery experiments, regardless of the random O₂²⁻ orientations and the symmetry in the crystal lattice. From XRD patterns analysis, the commercially available Li₂O₂ powder is confirmed to be the thermodynamic ground state Föppl-like structure. However, for Li₂O₂ compounds that are grown electrochemically under the environment of Li-O₂ cells, we found that the XRD patterns alone are not sufficient for structural identification of these metastable Li₂O₂ crystalline phases due to the poor crystallinity of the sample. In addition, the commonly known Raman signal of O₂²⁻ vibration mode is also found to be insufficient to validate the possible existence of these newly predicted Li₂O₂ crystal structures, as all of them similarly share the similar O₂²⁻ vibration mode. However considering that the discharge voltage in most Li-O₂ cells are typically several tenths of an eV below the thermodynamic equilibrium for the formation of ground state Föppl structure, the formation of these metastable Li₂O₂ crystal structures appears to be thermodynamically feasible.

  11. Photoreduction of metal nanostructures on periodically proton exchanged MgO-doped lithium niobate crystals

    SciTech Connect

    Balobaid, Laila; Craig Carville, N.; Collins, Liam; Rodriguez, Brian J.; Manzo, Michele; Gallo, Katia

    2013-10-28

    Local reactivity on periodically proton exchanged lithium niobate (PPE:LN) surfaces is a promising route for the fabrication of regularly spaced nanostructures. Here, using MgO-doped PPE:LN templates, we investigate the influence of the doping on the nanostructure formation as a function of the proton exchange (PE) depth. The deposition is found to occur preferentially along the boundary between MgO-doped LN and the PE region when the PE depth is at least 1.73 μm, however, for shallower depths, deposition occurs across the entire PE region. The results are found to be consistent with an increased photoconductivity of the MgO-doped LN.

  12. The dependence of the switching field on the intrinsic defects in lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Yan, Wenbo; Kong, Yongfa; Shi, Lihong; Li, Xiaochun; Xie, Xiang; Xu, Jingjun; Lou, Cibo; Liu, Hongde; Zhang, Guangyin

    2005-01-01

    Several near-stoichiometric lithium niobate (LiNbO3) plates for Periodically poled lithium niobate (PPLN) were prepared by vapor transport equilibrium (VTE) technique. External electric field poling was carried out on these samples. A linear dependence of the switching field on the concentration of anti-site niobium ions was observed. This linear relationship was explained by a two-dimensional model based on the dynamics of domain wall. In this model, the bowing of domain wall and the pinning role of anti-site niobium ions to the movement of domain wall were considered. The pinning-depinning transition of domain wall was attributed to the movement of anti-site niobium ions through the oxygen plane, which is due to the change of domain environment round anti-site niobium ions . A parameter of θ, denoting the ratio between the negative and positive domains round anti-site niobium ions , was introduced. The interaction between anti-site niobium ions and rounding domain environment was analyzed associating with the parameter θ. With the help of the shell-model theory, the force needed for anti-site niobium ions to pass through the oxygen plant was given as 1.696×10-9 N and the critical θc corresponding to domain reversal was calculated to be about 67° in degree. Using the fitting result of experiment data, the domain wall energy per unit area for LiNbO3 was also roughly calculated as 0.41 J/m2.

  13. High-rate lithium storage capability of cupric-cobaltous oxalate induced by unavoidable crystal water and functionalized graphene oxide

    NASA Astrophysics Data System (ADS)

    Feng, Fan; Kang, Wenpei; Yu, Faqi; Zhang, He; Shen, Qiang

    2015-05-01

    The combination of co-precipitation and dehydration is used to prepare hydrated and dehydrated cupric-cobaltous oxalates (Cu1/3Co2/3C2O4·xH2O, x = 1.4; Cu1/3Co2/3C2O4). Then, the hydrothermal treatment of these binary oxalates with freshly prepared graphene oxide (GO) and then dehydration are subsequently adopted to combine the hydrated or dehydrated oxalate with functionalized graphene oxide (FGO), resulting in another two targets of Cu1/3Co2/3C2O4·xH2O/FGO and Cu1/3Co2/3C2O4/FGO composites. These facilitate the comparative studies on the lithium storage capability of cupric oxalate-containing anode materials enhanced by unavoidable crystal water. As a lithium-ion battery anode, Cu1/3Co2/3C2O4·xH2O possesses a reversible capacity of 565.0 mAh g-1 at 1000 mA g-1 over 200 discharge-charge cycles, higher than that of the dehydrated counterpart (246.1 mAh g-1) but lower than those of FGO-based composites (Cu1/3Co2/3C2O4/FGO ∼ 951.2 mAh g-1; Cu1/3Co2/3C2O4·xH2O/FGO ∼ 1134.9 mAh g-1) continuously cycled at the exactly same conditions. At an ultra-high current density of 2000 or 5000 mA g-1, anode Cu1/3Co2/3C2O4·xH2O/FGO delivers a constant discharge capacity of 935.6 mAh g-1 in the 100th cycle or 388.9 mAh g-1 in the 1000th cycle, indicating a jointly positive effect of crystal water and FGO on the high-rate electrochemical performance of cupric-cobaltous oxalate for the first time.

  14. Effect of phase inversion on microporous structure development of Al 2O 3/poly(vinylidene fluoride-hexafluoropropylene)-based ceramic composite separators for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Jeong, Hyun-Seok; Kim, Dong-Won; Jeong, Yeon Uk; Lee, Sang-Young

    To improve the thermal shrinkage of the separators that are essential to securing the electrical isolation between electrodes in lithium-ion batteries, we develop a new separator based on a ceramic composite membrane. Introduction of microporous, ceramic coating layers onto both sides of a polyethylene (PE) separator allows such a progress. The ceramic coating layers consist of nano-sized alumina (Al 2O 3) powders and polymeric binders (PVdF-HFP). The microporous structure of the ceramic coating layers is observed to be crucial to governing the thermal shrinkage as well as the ionic transport of the ceramic composite separators. This microporous structure is determined by controlling the phase inversion, more specifically, nonsolvent (water) contents in the coating solutions. To provide a theoretical basis for this approach, a pre-investigation on the phase diagram for a ternary mixture comprising PVdF-HFP, acetone, and water is conducted. On the basis of this observation, the effect of phase inversion on the morphology and air permeability (i.e. Gurley value) of ceramic coating layers is systematically discussed. In addition, to explore the application of ceramic composite separators to lithium-ion batteries, the influence of the structural change in the coating layers on the thermal shrinkage and electrochemical performance of the separators is quantitatively identified.

  15. Structural disorder and optical properties of congruent lithium niobate crystals doped with zink and boron

    NASA Astrophysics Data System (ADS)

    Sidorov, N. V.; Palatnikov, M. N.; Yanichev, A. A.; Titov, R. A.; Teplyakova, N. A.

    2016-07-01

    From the concentration dependence of the widths and intensities of Raman lines and from the patterns of photoinduced light scattering, it is found that the mechanism of incorporation of Zn2+ cations into the LiNbO3 crystal structure changes with increasing concentration of zinc in the melt, which leads to an abrupt anisotropic expansion of oxygen octahedra along the polar axis. In this case, the number of kinks in the concentration dependence of linewidths (5) considerably exceeds the number of concentration threshold (2) known from the literature. It is shown that B3+ ions almost do not enter the cationic sublattice of the LiNbO3 crystal but changes the melt structure, so that the LiNbO3:B crystal is characterized by a high structural and optical homogeneity and a low photorefractive effect.

  16. Crystal field disorder effects in the optical spectra of Nd{sup 3+} and Yb{sup 3+}-doped calcium lithium niobium gallium garnets laser crystals and ceramics

    SciTech Connect

    Lupei, V.; Lupei, A.; Gheorghe, C.; Gheorghe, L.; Achim, A.; Ikesue, A.

    2012-09-15

    The optical spectroscopic properties of RE{sup 3+} (Nd, 1 at. % or Yb, 1 to 10 at. %)-doped calcium-lithium-niobium-gallium garnet (CLNGG) single crystals and ceramics in the 10 K-300 K range are analyzed. In these compositionally disordered materials, RE{sup 3+} substitute Ca{sup 2+} in dodecahedral sites and the charge compensation is accomplished by adjusting the proportion of Li{sup +}, Nb{sup 5+}, and Ga{sup 3+} to the doping concentration. The crystals and ceramics show similar optical spectra, with broad and structured (especially at low temperatures) bands whose shape depends on temperature and doping concentration. At 10 K, the Nd{sup 3+4}I{sub 9/2}{yields}{sup 4}F{sub 3/2,5/2} and Yb{sup 3+2}F{sub 7/2}{yields}{sup 2}F{sub 5/2} absorption bands, which show prospect for diode laser pumping, can be decomposed in several lines that can be attributed to centers with large differences in the crystal field. The positions of these components are the same, but the relative intensity depends on the doping concentration and two main centers dominate the spectra. Non-selective excitation evidences broad emission bands, of prospect for short-pulse laser emission, whereas the selective excitation reveals the particular emission spectra of the various centers. The modeling reveals that the nonequivalent centers correspond to RE{sup 3+} ions with different cationic combinations in the nearest octahedral and tetrahedral coordination spheres, and the most abundant two centers have 4Nb and, respectively, 3Nb1Li in the nearest octahedral sphere. At 300 K, the spectral resolution is lost. It is then inferred that the observed optical bands are envelopes of the spectra of various structural centers, whose resolution is determined by the relative contribution of the temperature-dependent homogeneous broadening and the effects of crystal field disordering (multicenter structure, inhomogeneous broadening). The relevance of spectroscopic properties for selection of pumping

  17. Piezoelectric and ferroelectric properties of lead-free niobium-rich potassium lithium tantalate niobate single crystals

    SciTech Connect

    Li, Jun; Li, Yang; Zhou, Zhongxiang; Guo, Ruyan; Bhalla, Amar S.

    2014-01-01

    Graphical abstract: - Highlights: • Lead-free K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} single crystals were grown using the top-seeded melt growth method. • The piezoelectric and ferroelectric properties of as-grown crystals were systematically investigated. • The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N. • The coercive fields of P–E hysteresis loops are quite small, about or less than 1 kV/mm. - Abstract: Lead-free potassium lithium tantalate niobate single crystals with the composition of K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} (abbreviated as KLTN, x = 0.51, 0.60, 0.69, 0.78) were grown using the top-seeded melt growth method. Their piezoelectric and ferroelectric properties in as-grown crystals have been systematically investigated. The phase transitions and Curie temperatures were determined from dielectric and pyroelectric measurements. Piezoelectric coefficients and electromechanical coupling factors in thickness mode, length-extensional mode and longitudinal mode were obtained. The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N are comparable to the lead-based PZT composition. The polarization versus electric field hysteresis loops show saturated shapes. In short, lead-free niobium-rich KLTN system possesses comparable properties to those in important lead-based piezoelectric material nowadays.

  18. Scintillation properties of the silver doped lithium iodide single crystals at room and low temperature

    NASA Astrophysics Data System (ADS)

    Khan, Sajid; Kim, H. J.; Lee, M. H.

    2016-06-01

    This study presents luminescence and scintillation properties of Silver doped LiI crystals. Single crystals of LiI: x% Ag (x=0.02, 0.05, 0.1 and 0.5) were grown by using the Bridgman technique. X-ray induced luminescence spectra show emission bands spanning from 275 nm to 675 nm, dominated by Ag+ band having a peak at 300 nm. Under UV-luminescence, a similar emission band was observed with the peak excitation wavelength of 265 nm. Energy resolution, light yield and decay time profiles of the samples were measured under a 137Cs γ-ray irradiation. The LiI(0.1%Ag) showed the highest light yield and the best energy resolution among the samples. The light yield of LiI(0.1%Ag) is higher than commercially available LiI(Eu) crystal (15,000±1500 ph/MeV). The LiI(Ag) samples exhibit three exponential decay time components except the LiI(0.02%Ag), where the fitting found two decay time components. Temperature dependences of emission spectra, light yield and decay time were studied from 300 K to 10 K. The LiI(0.1%Ag) crystal showed an increase in the light yield and a shortening of decay time with a decrease in temperature..

  19. High-pressure synthesis, crystal structure, and structural relationship of the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}

    SciTech Connect

    Haberer, Almut; Huppertz, Hubert

    2009-04-15

    Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} was synthesized under high-pressure/high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C, representing the first known ytterbium fluoride borate. The compound exhibits isolated BO{sub 3}-groups next to ytterbium cations and fluoride anions, showing a structure closely related to the other known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}. Monoclinic Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} crystallizes in space group C2/c with the lattice parameters a=2028.2(4) pm, b=602.5(2) pm, c=820.4(2) pm, and beta=100.63(3){sup o} (Z=4). Three different ytterbium cations can be identified in the crystal structure, each coordinated by nine fluoride and oxygen anions. None of the five crystallographically independent fluoride ions is coordinated by boron atoms, solely by trigonally-planar arranged ytterbium cations. In close proximity to the above mentioned compounds RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}, Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} can be described via alternating layers with the formal compositions 'YbBO{sub 3}' and 'YbF{sub 3}' in the bc-plane. - Graphical abstract: High-pressure/high-temperature synthesis (multianvil technique) led to the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}, built up from isolated BO{sub 3}-groups. The compound shows structural relations to the known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}.

  20. Lithium-bearing fluor-arfvedsonite from Hurricane Mountain, New Hampshire: A crystal-chemical study

    USGS Publications Warehouse

    Hawthorne, F.C.; Oberti, R.; Ottolini, L.; Foord, E.E.

    1996-01-01

    The structures of two crystals of Li-bearing fluor-arfvedsonite (1) (K0.32Na0.68)Na2(Li0.48Fe 2+2.83Mn2+0.10Zn 0.06Fe3+1.46Ti0.07) (Si7.88Al0.12)O22[Fu1.15(OH) 0.85] and (2) (K0.25Na0.75)Na2(Li0.48Fe 2+2.84Mn2+0.11Zn 0.05Fe3+1.45Ti0.07)(Si 7.89Al0.11)O22[F1.35(OH) 0.65] from a granitic pegmatite, Hurricane Mountain, New Hampshire, have been refined to R indices of 1.5(1.6)% based on 1380(1387) reflections measured with MoK?? X-radiation. The unit cell parameters are (1) a 9.838(4), b 17.991(6), c 5.315(2) A??, 103.78(3)??, V 913.7 A??3 and (2) a 9.832(3), b 17.990(7), c 5.316(3) A??, ?? 103.79(3)??, V 913.2 A??3. Site-scattering refinement shows Li to be completely ordered at the M(3) site in these crystals. The amphibole composition is intermediate between fluor-arfvedsonite and fluor-ferro-leakeite with a small component (???10%) of fluor-ferro-ferri-nybo??ite. These amphibole crystals project into miarolitic cavities in a pegmatitic phase of a riebeckite granite. The early-crystallizing amphibole is close to fluor-ferro-leakeite in composition, but becomes progressively depleted in Li and F as crystals project out into miarolitic cavities; the final amphibole to crystallize is a fibrous Li-poor riebeckite. Li plays a significant role in late-stage fractionation involving the crystallization of alkali amphibole in peralkaline granitic environments.

  1. Synthesis and Crystal Structures of Zirconium Phosphate Fluorides with New 2D and 3D Structure Types

    NASA Astrophysics Data System (ADS)

    Wloka, Martin; Troyanov, Sergei I.; Kemnitz, Erhard

    2000-01-01

    Three new zirconium phosphate fluorides, [amH2]0.5 [Zr2(PO4)(HPO4)2F2]·0.5H2O (1), [amH2]1.5[Zr3(PO4)3F6]·1.5H2O (2) (am=trans-1,4-diaminocyclohexane for 1 and 2), and [amH2]0.5[Zr3(PO4)3(HPO4)F2]·1.5H2O (am=2,2-dimethyl-1,3-diaminopropane) (3), were synthesized under hydrothermal conditions and structurally characterized. Zr is octahedrally coordinated in all three structures. In 1, the octahedra consist of ZrO6 and ZrO4F2 units. Compound 2 is made exclusively of ZrO4F2. In 3, there are three different types of Zr-octahedra, namely, ZrO6, ZrO5F, and ZrO4F2. The Zr octahedra and PO4 tetrahedra are connected via non-OH oxygen atoms. In 1 and 2, all F atoms are terminal, whereas in 3, one of the two F atoms bridges between the ZrO5F and ZrO4F2 octahedra. In structures 1 and 2 with higher F/Zr ratios, two-dimensional inorganic networks exist. The inorganic sheets are connected by the protonated templates via N-H···F and in 1 additionally by O-H···F hydrogen bonds. In 3, the lower F/Zr ratio results in the formation of a three-dimensional inorganic framework with characteristic 'double' channels in which the highly disordered templates are located. The existence of several structure types in the ZrPOF-n family is discussed on the basis of different template geometry and F/Zr ratios.

  2. Synthesis and crystal structure of the lithium perrhenate monohydrate LiReO 4·H 2O

    NASA Astrophysics Data System (ADS)

    Abakumov, Artem M.; Rozova, Marina G.; Shpanchenko, Roman V.; Mironov, Andrei V.; Antipov, Evgeny V.; Bramnik, Kirill G.

    2001-07-01

    A new monohydrate of lithium perrhenate LiReO 4·H 2O was prepared by dehydration of LiReO 4·1.5H 2O at room temperature. The single crystals of LiReO 4·H 2O were obtained by crystallisation from the isoamyl acetate solution of LiReO 4·1.5H 2O. The structure of monohydrate ( a=5.6674(4), b=10.771(1), c=7.4738(7) Å, β=102.422(7)°, R1=0.0414, space group P2 1/ a, Z=4) is built up from LiO 3(H 2O) 2 trigonal bipyramids and ReO 4 tetrahedra sharing common edges and corners inside the layers. The layers are connected together by hydrogen bonds. The relationships between the structures of sesquihydrate, monohydrate and anhydrous LiReO 4 are discussed.

  3. Nucleation and Crystallization as Induced by Bending Stress in Lithium Silicate Glass Fibers

    NASA Technical Reports Server (NTRS)

    Reis, Signo T.; Kim, Cheol W.; Brow, Richard K.; Ray, Chandra S.

    2003-01-01

    Glass Fibers of Li2O.2SiO2 (LS2) and Li2O.1.6SiO2 (LS1.6) compositions were heated near, but below, the glass transition temperature for different times while subjected to a constant bending stress of about 1.2 GPa. The nucleation density and the crystallization tendency estimated by differential thermal analysis (DTA) of a glass sample in the vicinity of the maximum of the bending stress increased relative to that of stress-free glass fibers. LS2 glass fibers were found more resistant to nucleation and crystallization than the Ls1.6 glass fibers. These results are discussed in regards to shear thinning effects on glass stability.

  4. Femtosecond-induced micostructures in Magnesium- doped Lithium Niobate crystals with high repetition rate

    NASA Astrophysics Data System (ADS)

    Kan, Hongli; Zhang, Shuanggen; Zhai, Kaili; Ma, Xiurong; Luo, Yiming; Hu, Minglie; Wang, Qingyue

    2016-02-01

    In this paper, heat accumulation effect of MgO: LN crystal irradiated by femtosecond pulses was analyzed by a developed thermal conduction model in terms of the spatial and temporal distribution of the absorbed laser energy. Using the focused femtosecond pulses about 61 fs at 1040 nm with a repetition rate of 52 MHz, ablation morphologies under different exposure time and average power were obtained experimentally. The measured laser-induced damage threshold of X-, Y- and Z-cut MgO: LN crystals are 0.82 mJ/cm2, 0.74 mJ/cm2 and 0.76 mJ/cm2, respectively, and based on the measurement achieved in the Lab the differences in the ablation morphologies were analyzed in detail.

  5. Study of structural and ferromagnetic resonance properties of spinel lithium ferrite (LiFe{sub 5}O{sub 8}) single crystals

    SciTech Connect

    Pachauri, Neha; Khodadadi, Behrouz; Mewes, Tim; Althammer, Matthias; Singh, Amit V.; Gupta, Arunava; Loukya, B.; Datta, Ranjan; Iliev, Milko; Bezmaternykh, Leonard; Gudim, Irina

    2015-06-21

    The effect of B-site cation ordering on the room temperature structural and ferromagnetic resonance (FMR) properties of single crystal spinel lithium ferrite (LiFe{sub 5}O{sub 8}, LFO) have been investigated. A detailed microstructural analysis is done through X-ray diffraction, polarized Raman spectroscopy, and transmission electron microscopy (TEM) to examine the effect of post-annealing on the B-site cation ordering. The X-ray diffraction pattern of the as-grown crystal indicates a disordered state of the crystal. However, the annealed sample shows additional superlattice reflections corresponding to the ordered phase. This ordering is further confirmed by Raman spectra and TEM images, which reveal ordering of Li and Fe ions at the octahedral sites contrasting with the relatively high degree of octahedral site disorder in the as-grown crystal. To study the effect of B-site ordering on the magnetic properties and FMR linewidth, vibrating sample magnetometry and broadband FMR measurements have been performed for both the ordered and disordered phases of lithium ferrite. The value of saturation magnetization for both phases is ∼290 emu/cm{sup 3}. A single mode FMR profile is observed for both phases with little distortion. The linewidth characteristics of the ordered and disordered phases of lithium ferrite phases are compared, and it is observed that the linewidth is independent of the cation ordering. Both the phases exhibit a low linewidth (∼26 Oe at 30 GHz) and the effective damping parameter for the as-grown and annealed samples is determined to be 0.0021 ± 0.0001.

  6. Patterning of silver nanoparticles on visible light-sensitive Mn-doped lithium niobate photogalvanic crystals

    SciTech Connect

    Liu Xiaoyan; Ohuchi, Fumio; Hatano, Hideki; Takekawa, Shunji; Kitamura, Kenji

    2011-08-01

    Visible light-induced polarization-dependent photochemical deposition of silver nanoparticles (AgNPs) has been demonstrated using Mn-doped congruent LiNbO{sub 3} (CLN) single crystals. Mn-doped CLN has a strong absorption over a wide region of the visible spectrum that allowed effective visible light irradiation for photochemical deposition. The AgNPs deposition on Mn-doped CLN was compared with that on non-doped congruent LiNbO{sub 3}, and together these further confirmed that the photochemical deposition on LiNbO{sub 3} is caused by the strong photogalvanic effect.

  7. Crystal structure of a dinuclear Co(II) complex with bridging fluoride ligands: di-μ-fluorido-bis-{tris-[(6-methyl-pyridin-2-yl)meth-yl]amine}-dicobalt(II) bis-(tetra-fluorido-borate).

    PubMed

    Inomata, Masataka; Suenaga, Yusaku

    2014-11-01

    Reaction of Co(BF4)2·6H2O with tris-[(6-methyl-pyridin-2-yl)meth-yl]amiine in methanol results in a fluoride abstraction from BF4 (-), yielding the unexpected title compound, [Co2F2(C21H24N4)2](BF4)2. The complex cation consists of two inversion-related [Co(C21H24N4)](2+) moieties bridged by a pair of fluoride ligands. The Co(II) cation is six-coordinated in a distorted octa-hedral geometry and forms a +II high-spin state. In the crystal, the complex cation and the BF4 (-) anion are connected by C-H⋯F hydrogen bonds, forming a three-dimensional network. An intra-molecular C-H⋯F hydrogen bond is also observed. PMID:25484774

  8. Preparation and stress evolution of sol-gel SiO2 antireflective coatings for small-size anisotropic lithium triborate crystals

    NASA Astrophysics Data System (ADS)

    Tian, Bingtao; Wang, Xiaodong; Niu, Yanyan; Zhang, Jinlong; Zhang, Qinghua; Zhang, Zhihua; Wu, Guangming; Zhou, Bin; Shen, Jun

    2016-04-01

    Lithium triborate (LiB3O5, LBO) crystal is now one of the most useful nonlinear optical materials for frequency conversion of high power lasers. The use of the crystal, however, has been hampered by the unavailability of antireflective (AR) coatings with high laser damage resistance. In this work, a "point contact" dip-coating method is developed to prepare sol-gel SiO2 AR coatings on small-size LBO crystals. Using this approach, we obtain a homogenous coating surface on an 8 mm×8 mm×3 mm LBO crystal. The stress measurements show that the stresses in sol-gel SiO2 coatings vary with the time of natural drying, which is beyond our expectation. The anisotropic Young's modulus of the LBO crystal and the different evolution tendency of the stress in the different SiO2 coating layers are found to be responsible for the crack of the double-layer AR coatings on anisotropic LBO crystal. Meanwhile, the resulting coatings on LBO crystal achieve a LIDT of over 15 J/cm2 (532 nm, 3ns) and the coated LBO is expected to have a transmittance of over 99% at 800 nm.

  9. Synthesis, crystal structure and properties of a new lead fluoride borate, Pb{sub 3}OBO{sub 3}F

    SciTech Connect

    Zhao, Wenwu; Pan, Shilie; Dong, Xiaoyu; Li, Junjie; Tian, Xuelin; Fan, Xiaoyun; Chen, Zhaohui; Zhang, Fangfang

    2012-04-15

    Graphical abstract: The structure of Pb{sub 3}OBO{sub 3}F consists of two distortional Pb-centered tetrahedra and BO{sub 3} triangles which are all symmetrical with each other respectively in the gestalt structure to the extent that the Pb{sub 3}OBO{sub 3}F compound crystallizes in the symmetrical space group. Highlights: Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F has been grown from PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. Black-Right-Pointing-Pointer It crystallizes in the orthorhombic system, space group Pbcm. Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles. -- Abstract: A new compound, Pb{sub 3}OBO{sub 3}F, has been grown by the high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system. It crystallizes in the orthorhombic system, space group Pbcm with unit-cell parameters a = 7.6313(14) Angstrom-Sign , b = 6.5229(12) Angstrom-Sign , c = 11.906(2) Angstrom-Sign , Z = 4, volume = 592.66(19) Angstrom-Sign {sup 3}. The structure of the compound is solved by the direct methods and refined to R{sub 1} = 0.0528 and wR{sub 2} = 0.1400. Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles which build up the symmetrical chains extended along the c-axis. The powder X-ray diffraction pattern of the Pb{sub 3}OBO{sub 3}F has been measured. Functional groups presented in the sample were identified by Fourier transform infrared spectrum.

  10. Face-centered-cubic lithium crystals formed in mesopores of carbon nanofiber electrodes.

    PubMed

    Lee, Byoung-Sun; Seo, Jong-Hyun; Son, Seoung-Bum; Kim, Seul Cham; Choi, In-Suk; Ahn, Jae-Pyoung; Oh, Kyu Hwan; Lee, Se-Hee; Yu, Woong-Ryeol

    2013-07-23

    In the foreseeable future, there will be a sharp increase in the demand for flexible Li-ion batteries. One of the most important components of such batteries will be a freestanding electrode, because the traditional electrodes are easily damaged by repeated deformations. The mechanical sustainability of carbon-based freestanding electrodes subjected to repeated electrochemical reactions with Li ions is investigated via nanotensile tests of individual hollow carbon nanofibers (HCNFs). Surprisingly, the mechanical properties of such electrodes are improved by repeated electrochemical reactions with Li ions, which is contrary to the conventional wisdom that the mechanical sustainability of carbon-based electrodes should be degraded by repeated electrochemical reactions. Microscopic studies reveal a reinforcing mechanism behind this improvement, namely, that inserted Li ions form irreversible face-centered-cubic (FCC) crystals within HCNF cavities, which can reinforce the carbonaceous matrix as strong second-phase particles. These FCC Li crystals formed within the carbon matrix create tremendous potential for HCNFs as freestanding electrodes for flexible batteries, but they also contribute to the irreversible (and thus low) capacity of HCNFs.

  11. Frequency non-degenerate sequential excitation of the impurity trapped exciton in strontium fluoride crystals doped with ytterbium

    SciTech Connect

    Senanayake, Pubudu S.; Hughes-Currie, Rosa B.; Wells, Jon-Paul R.; Reid, Michael F.; Berden, Giel; Reeves, Roger J.; Meijerink, Andries

    2015-04-07

    We model the dynamic behaviour observed for impurity-trapped excitons in SrF{sub 2}:Yb{sup 2+} using transient photoluminescence enhancement induced via a two-frequency, sequential excitation process employing an UV optical parametric amplifier synchronized to an IR free electron laser (FEL). We observe sharp transitions interpreted as a change of state of the localized hole and broad bands interpreted as a change of state of the delocalized electron. Our modeling indicates that the 4f crystal-field interaction is 25% smaller than in CaF{sub 2}. The photoluminescence enhancement transients are analyzed across a range of excitation frequencies using a system of rate equations. The temporal behavior is explained in terms of intra-excitonic relaxation, local lattice heating by the FEL, and liberation of electrons from trap states.

  12. The missing hydrate AlF3·6H2Odbnd [Al(H2O)6]F3: Ionothermal synthesis, crystal structure and characterization of aluminum fluoride hexahydrate

    NASA Astrophysics Data System (ADS)

    Wang, Guangmei; Mudring, Anja-Verena

    2016-11-01

    AlF3 is a strong Lewis acid and several hydrates of it are known, namely the monohydrate, the trihydrate (of which two polymorphs have been described) and the nonohydrate, which forms in the abundance of water, as well as a more complex fluoride of composition Al0.82□0.18F2.46(H2O)0.54 whose structure has been related to the ReO3 type. The monohydrate features edge connected [AlF6] octahedra, in the tri- and nonahydrate mixed F/O coordination of aluminum is observed. Here we report on a new aluminium fluoride hydrate, AlF3·6H2O, which could be obtained via ionothermal synthesis in the ionic liquid n-hexyl-pyridinium tetrafluoroborate. The ionic liquid serves in the synthesis of AlF3·6H2O as the reaction partner (fluoride source) and solvent. Overmore it controls the water activity allowing access to the missing AlF3·6H2O. Single-crystal X-ray diffraction analysis of AlF3·6H2O shows that it crystallizes in the anti-Li3Bi-type of structure according to F3[Al(H2O)6] (Fm-3m, a = 893.1(2) pm, Z = 4) featuring hexaaqua aluminium(III) cations and isolated fluoride anions. The compound was further characterized by powder X-ray diffraction, TG/DTA, IR analyses.

  13. Composite Gel Polymer Electrolyte Based on Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) with Modified Aluminum-Doped Lithium Lanthanum Titanate (A-LLTO) for High-Performance Lithium Rechargeable Batteries.

    PubMed

    Le, Hang T T; Ngo, Duc Tung; Kalubarme, Ramchandra S; Cao, Guozhong; Park, Choong-Nyeon; Park, Chan-Jin

    2016-08-17

    A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites. PMID:27463563

  14. Nonlinear Elastic Behavior of Piezoelectric Trigonal Crystals: Measurements on Quartz and Lithium-Niobate

    NASA Astrophysics Data System (ADS)

    Latimer, Paul Jerry

    The ultrasonic harmonic generation technique previously used to measure third-order elastic (TOE) constants of crystals of cubic symmetry has been extended to measurement of crystals of trigonal symmetry. The theory for nonpiezoelectric trigonal crystals of J. Philip {Technical Report No. 22, Office of Naval Research, Contract No. N00014 -81-K-0229 (to be published in 1983)} has been combined with the piezoelectric theory of McMahon {J. Acoust. Soc. Am. 44, 1007 (1968)} to determine the effective TOE constants in a piezoelectric solid, and correction has been made in McMahon's expression. Measurements in weakly piezoelectric quartz have produced values of C(,111) and C(,333) which agree within experimental uncertainty with values of R. N. Thurston, H. J. McSkimin and P. Andreatch, Jr. {J. Appl. Phys. 37, 267 (1966)} and R. Stern and R. T. Smith {J. Acoust. Soc. Am. 44, 640 (1968)} after corrections have been made for the effect of diffraction on the data. Measurements in strongly piezoelectric LiNbO(,3) have resulted in values which agree reasonably well with those of J. Philip and M. A. Breazeale {Proc. IEEE Ultrasonics Symposium, Vol. 2 (1982) } but disagree with those of C. Y. Nakagawa, K. Yamanouchi and K. Shibayama {J. Appl. Phys. 44, 3969 (1973) }. There is indication of some sample dependence of the values of both the second-order elastic constants as well as the third-order elastic constants of LiNbO(,3) samples currently available. In the course of measurement of the TOE constants a negative nonlinearity parameter was observed for the Piezoelectric {100} direction in quartz. This peculiarity is impossible for thermodynamic reasons in fluids, but has been observed once previously in fused silica {J. Bains and M. A. Breazeale, J. Acoust, Soc. Am. 57, 745 (1975)}. The nonlinearity parameter appears to be positive for the piezoelectric {001 } direction in LiNbO(,3). The data presented are for the "piezoelectrically stiffened" TOE constants; however, there are

  15. Effect of lithium on the properties of a liquid crystal formed by sodium dodecylsulphate and decanol in aqueous solution.

    PubMed

    Bahamonde-Padilla, V E; Espinoza, Javier; Weiss-López, B E; Cascales, J J López; Montecinos, R; Araya-Maturana, R

    2013-07-01

    Understanding the molecular interactions that rule the physicochemical properties of molecular assemblies is of particular interest when trying to explain the behavior of much more complicated systems, such as the cell membranes. This work was devoted to study a discotic nematic lyotropic liquid crystal, formed by sodium dodecylsulphate (3% SDS-d25) and decanol (20% DeOH-α-d2), dissolved in aqueous solutions (0.1% D2O) of Na2SO4 or Li2SO4. The average size of the aggregates was estimated using fluorescence quenching experiments, and their dynamics were studied by measuring the (2)H-NMR quadrupole splitting (ΔνQ) and the longitudinal relaxation times (T1) of the deuterated species. To provide an atomic insight into these assemblies, molecular dynamics simulations of the systems were carried out with atomic detail. As a previous step in this study, a reparameterization of the standard GROMOS 87 force field was required to perform the equilibrated simulations and to prevent instabilities emerging during the simulations. Finally, an excellent agreement between simulation and experimental data was obtained. In addition, variations in the long range electrostatic interactions at the aggregate/solution interface, the orientation and the reorientational relaxation time of the water dipole, the translational diffusion coefficient of sodium ions, and the amphiphile-counterion coordination associated with the presence of Li(+) in the solution were other key aspects investigated to explain the variation in the quadrupole splittings (ΔνQ) in the presence of lithium in solution.

  16. Optical properties of trigonal single crystals (Yb,Tm)Al{sub 3}(BO{sub 3}){sub 4} grown from fluxes based on the bismuth and lithium molybdates

    SciTech Connect

    Temerov, V. L. Sokolov, A. E.; Sukhachev, A. L.; Bovina, A. F.; Edel'man, I. S.; Malakhovskii, A. V.

    2008-12-15

    The conditions for synthesis of Yb{sub x}Tm{sub 1-x}Al{sub 3}(BO{sub 3}){sub 4} (x = 0, 0.1, 0.2, 1.0) single crystals from fluxes based on bismuth trimolybdate Bi{sub 2}Mo{sub 3}O{sub 12} and lithium molybdate Li{sub 2}MoO{sub 4} are investigated. It is proposed to grow them by the group method on seeds. The polarized optical absorption spectra are measured for two mutually orthogonal linear polarizations at temperatures of 100 and 300 K.

  17. Gd{sub 4}B{sub 4}O{sub 11}F{sub 2}: Synthesis and crystal structure of a rare-earth fluoride borate exhibiting a new 'fundamental building block' in borate chemistry

    SciTech Connect

    Haberer, Almut; Kaindl, Reinhard; Huppertz, Hubert

    2010-02-15

    A new gadolinium fluoride borate Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} was yielded in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C. Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} crystallizes monoclinically in the space group C2/c with the lattice parameters a=1361.3(3) pm, b=464.2(2) pm, c=1374.1(3) pm, and beta=91.32(3){sup o} (Z=4). The crystal structure exhibits a structural motif not yet reported from borate chemistry: two BO{sub 4}-tetrahedra (square) and two BO{sub 3}-groups (DELTA) are connected via common corners, leading to the fundamental building block 2DELTA2square:DELTAsquaresquareDELTA. In the two crystallographically identical BO{sub 4}-tetrahedra, a distortion resulting in a very long B-O-bond is found. - Graphical abstract: A new gadolinium fluoride borate Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} could be synthesized via high-pressure/high-temperature synthesis (multianvil technique). The crystal structure exhibits a structural motif not yet reported from borate chemistry: two BO{sub 4}-tetrahedra (square) and two BO{sub 3}-groups (DELTA) are connected via common corners, leading to the fundamental building block 2DELTA2square:DELTAsquaresquareDELTA.

  18. Graphite Fluoride Fiber Composites For Heat Sinking

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Long, Martin; Stahl, Mark

    1989-01-01

    Graphite fluoride fiber/polymer composite materials consist of graphite fluoride fibers in epoxy, polytetrafluoroethylene, or polyimide resin. Combines high electrical resistivity with high thermal conductivity and solves heat-transfer problems of many electrical systems. Commercially available in powder form, for use as dry lubricant or cathode material in lithium batteries. Produced by direct fluorination of graphite powder at temperature of 400 to 650 degree C. Applications include printed-circuit boards for high-density power electronics, insulators for magnetic-field cores like those found in alternators and transformers, substrates for thin-film resistors, and electrical-protection layers in aircraft de-icers.

  19. Thermodynamic and kinetic characteristics of variations in shapes of ridges formed on {l_brace}100{r_brace} lithium fluoride surfaces

    SciTech Connect

    Bullard, J.W.; Glaeser, A.M.; Searcy, A.W.

    1991-12-01

    channels with widths in the range form 5 {mu}m were formed in {l_brace}100{r_brace} surfaces of LiF single crystals by a photolithographic technique. Specimens annealed at or above 0.90 T{mu}m, where T{mu} is the melting point, and then quenched showed the channels and the ridges between them develop rounded profiles. Evolution of these profiles was evaluated for the various channel widths and for interchannel ridge spacings of 5 to 100 {mu}m in terms of: (a) an accepted theoretical model for a surface diffusion controlled process, and (b) a model which assumes that shape changes depend only on the relative energies of attachment of atoms in surface sites with various surface curvatures. Either model is consistent with the experimental observations to within the reproducibility in measurements.

  20. Investigation on crystalline perfection, optical transmittance, birefringence, temperature-dependent refractive index, laser damage threshold and pyroelectric characteristics of inversely soluble lithium sulfate monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Silambarasan, A.; Rajesh, P.; Bhatt, Rajeev; Bhaumik, Indranil; Karnal, A. K.; Ramasamy, P.; Gupta, P. K.

    2016-08-01

    Bulk prismatic lithium sulfate monohydrate (LSMH) single crystals were grown by seed rotation with slow heating method from aqueous solution. Small FWHM obtained from high-resolution X-ray diffraction spectrum shows that the crystals grown by this method have less defects and absence of low-angle grain boundaries. The high transmittance and low reflectance nature of the grown crystal was observed using UV-Vis-NIR spectrometer. The principal refractive indices of a LSMH crystal have been measured by a prism coupling method for the wavelengths of 0.407, 0.532, 0.828, 1.064 and 1.551 µm at room temperature, and Sellmeier equations are determined from the fitting of the data point. The refractive index data confirm that LSMH crystal is negative biaxial and the optic axis lies in YZ plane with an angle (2 V y ) of 51.74° with respect to y axis at 532 nm wavelength. The thermo-optic coefficients were determined from the temperature-dependent refractive indices measured in the range of 30-125 °C for the wavelengths of 532 and 1064 nm. The surface laser damage threshold studies reveal the higher optical radiation stability against 532-nm laser. The pyroelectric coefficients and pyroelectric figure of merit were determined from the pyroelectric current measurement by the Byer and Roundy method.

  1. Three-Dimensional (3D) Bicontinuous Hierarchically Porous Mn2O3 Single Crystals for High Performance Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Huang, Shao-Zhuan; Jin, Jun; Cai, Yi; Li, Yu; Deng, Zhao; Zeng, Jun-Yang; Liu, Jing; Wang, Chao; Hasan, Tawfique; Su, Bao-Lian

    2015-10-01

    Bicontinuous hierarchically porous Mn2O3 single crystals (BHP-Mn2O3-SCs) with uniform parallelepiped geometry and tunable sizes have been synthesized and used as anode materials for lithium-ion batteries (LIBs). The monodispersed BHP-Mn2O3-SCs exhibit high specific surface area and three dimensional interconnected bimodal mesoporosity throughout the entire crystal. Such hierarchical interpenetrating porous framework can not only provide a large number of active sites for Li ion insertion, but also good conductivity and short diffusion length for Li ions, leading to a high lithium storage capacity and enhanced rate capability. Furthermore, owing to their specific porosity, these BHP-Mn2O3-SCs as anode materials can accommodate the volume expansion/contraction that occurs with lithium insertion/extraction during discharge/charge processes, resulting in their good cycling performance. Our synthesized BHP-Mn2O3-SCs with a size of ~700 nm display the best electrochemical performance, with a large reversible capacity (845 mA h g-1 at 100 mA g-1 after 50 cycles), high coulombic efficiency (>95%), excellent cycling stability and superior rate capability (410 mA h g-1 at 1 Ag-1). These values are among the highest reported for Mn2O3-based bulk solids and nanostructures. Also, electrochemical impedance spectroscopy study demonstrates that the BHP-Mn2O3-SCs are suitable for charge transfer at the electrode/electrolyte interface.

  2. How Does Fluoride Work?

    MedlinePlus

    ... Help White House Lunch Recipes How Does Fluoride Work? KidsHealth > For Kids > How Does Fluoride Work? Print A A A Text Size There's fluoride ... even in your water. But how does it work to keep teeth healthy? Let's find out. Fluoride ...

  3. A5RE4X[TO4]4 crystal growth: Fluoride flux synthesis of Na5Ln4F[GeO4]4 (Ln=Pr, Nd), the first quaternary germanate oxyfluorides

    NASA Astrophysics Data System (ADS)

    Latshaw, Allison M.; Wilkins, Branford O.; Morrison, Gregory; Smith, Mark D.; zur Loye, Hans-Conrad

    2016-07-01

    Crystals of Na5Pr4F[GeO4]4 and Na5Nd4F[GeO4]4 were synthesized using a eutectic sodium fluoride, sodium chloride flux. Both compounds crystallize in the tetragonal space group I-4 with lattice parameters of a=12.1173(4) Å and c=5.6795(2) Å (Pr) and of a=12.0642(17) Å and c=5.6674(11) Å (Nd). The structure of the reported compounds is three-dimensional with face and corner sharing lanthanide polyhedra which edge and corner share with isolated germanium tetrahedra. These novel compositions represent the first example of quaternary germanium containing oxyfluorides.

  4. Inheritance of Crystallographic Orientation during Lithiation/Delithiation Processes of Single-Crystal α-Fe2O3 Nanocubes in Lithium-Ion Batteries.

    PubMed

    Ma, Xiaowei; Zhang, Manyu; Liang, Chongyun; Li, Yuesheng; Wu, Jingjing; Che, Renchao

    2015-11-01

    Iron oxides are very promising anode materials based on conversion reactions for lithium-ion batteries (LIBs). During conversion processes, the crystal structure and composition of the electrode material are drastically changed. Surprisingly, in our study, inheritance of a crystallographic orientation was found during lithiation/delithiation processes of single-crystal α-Fe2O3 nanocubes by ex situ transmission electron microscopy. Single-crystal α-Fe2O3 was first transformed into numerous Fe nanograins embedded in a Li2O matrix, and then the conversion between Fe and FeO nanograins became the main reversible electrochemical reaction for energy storage. Interestingly, these Fe/FeO nanograins had almost the same crystallographic orientation, indicating that the lithiated/delithiated products can inherit the crystallographic orientation of single-crystal α-Fe2O3. This finding is important for understanding the detailed electrochemical conversion processes of iron oxides, and this feature may also exist during lithiation/delithiation processes of other transition-metal oxides.

  5. Fluoride and Water (For Parents)

    MedlinePlus

    ... Things to Know About Zika & Pregnancy Fluoride and Water KidsHealth > For Parents > Fluoride and Water Print A ... to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

  6. Lithium niobate explosion monitor

    DOEpatents

    Bundy, Charles H.; Graham, Robert A.; Kuehn, Stephen F.; Precit, Richard R.; Rogers, Michael S.

    1990-01-01

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier.

  7. Lithium niobate explosion monitor

    DOEpatents

    Bundy, C.H.; Graham, R.A.; Kuehn, S.F.; Precit, R.R.; Rogers, M.S.

    1990-01-09

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier. 8 figs.

  8. Ferroelectric nanocomposites of polyvinylidene fluoride/polymethyl methacrylate blend and BaTiO3 particles: Fabrication of β-crystal polymorph rich matrix through mechanical activation of the filler

    NASA Astrophysics Data System (ADS)

    Mofokeng, Tladi G.; Luyt, Adriaan S.; Pavlović, Vera P.; Pavlović, Vladimir B.; Dudić, Duško; Vlahović, Branislav; Djoković, Vladimir

    2014-02-01

    Nanocomposites of polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) blend and mechanically activated barium titanate (BaTiO3) particles were prepared by melt mixing. Modification of filler by means of mechanical activation has a profound effect on the crystallization of PVDF in the blend matrix. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form. The introduction of activated particles reduces the overall crystallinity but slightly affects the crystallization and melting temperatures of the matrix. Dielectric spectroscopy revealed that at fixed filler content the dielectric constant of the blend increases with decreasing of the particle size (increasing of the activation time). A similar trend was observed for the storage moduli in dynamic mechanical analysis; the stiffness of the composite was higher when mechanically activated particles were used.

  9. Unique 1D Co3O4 crystallized nanofibers with (220) oriented facets as high-performance lithium ion battery anode material

    NASA Astrophysics Data System (ADS)

    Tan, Yanli; Gao, Qiuming; Li, Zeyu; Tian, Weiqian; Qian, Weiwei; Yang, Chunxiao; Zhang, Hang

    2016-05-01

    A novel one-step hydrothermal and calcination strategy was developed to synthesize the unique 1D oriented Co3O4 crystal nanofibers with (220) facets on the carbon matrix derived from the natural, abundant and low cost wool fibers acting as both carbon precursor and template reagent. The resultant W2@Co3O4 nanocomposite exhibited very high specific capacity and favorable high-rate capability when used as anode material of lithium ion battery. The high reversible Li+ ion storage capacity of 986 mAh g‑1 was obtained at 100 mA g‑1 after 150 cycles, higher than the theoretical capacity of Co3O4 (890 mAh g‑1). Even at the higher current density of 1 A g‑1, the electrode could still deliver a remarkable discharge capacity of 720 mAh g‑1 over 150 cycles.

  10. Unique 1D Co3O4 crystallized nanofibers with (220) oriented facets as high-performance lithium ion battery anode material

    PubMed Central

    Tan, Yanli; Gao, Qiuming; Li, Zeyu; Tian, Weiqian; Qian, Weiwei; Yang, Chunxiao; Zhang, Hang

    2016-01-01

    A novel one-step hydrothermal and calcination strategy was developed to synthesize the unique 1D oriented Co3O4 crystal nanofibers with (220) facets on the carbon matrix derived from the natural, abundant and low cost wool fibers acting as both carbon precursor and template reagent. The resultant W2@Co3O4 nanocomposite exhibited very high specific capacity and favorable high-rate capability when used as anode material of lithium ion battery. The high reversible Li+ ion storage capacity of 986 mAh g−1 was obtained at 100 mA g−1 after 150 cycles, higher than the theoretical capacity of Co3O4 (890 mAh g−1). Even at the higher current density of 1 A g−1, the electrode could still deliver a remarkable discharge capacity of 720 mAh g−1 over 150 cycles. PMID:27217201

  11. High-pressure synthesis and crystal structure of the lithium borate HP-LiB{sub 3}O{sub 5}

    SciTech Connect

    Neumair, Stephanie C.; Vanicek, Stefan; Kaindl, Reinhard; Toebbens, Daniel M.; Wurst, Klaus; Huppertz, Hubert

    2011-09-15

    The new lithium borate HP-LiB{sub 3}O{sub 5} was synthesized under high-pressure/high-temperature conditions of 6 GPa and 1050 deg. C in a multianvil press with a Walker-type module. The compound crystallizes in the space group Pnma (no. 62) with the lattice parameters a=829.7(2), b=759.6(2), and c=1726.8(4) pm (Z=16). The high-pressure compound HP-LiB{sub 3}O{sub 5} is built up from a three-dimensional network of BO{sub 4} tetrahedra and BO{sub 3} groups, which incorporates Li{sup +} ions in channels along the b-axis. Band assignments of measured IR- and Raman spectra were done via quantum-mechanical calculations. Additionally, the thermal behavior of HP-LiB{sub 3}O{sub 5} was investigated. - Graphical abstract: The new high-pressure compound HP-LiB{sub 3}O{sub 5} is built up from a three-dimensional network of BO4 tetrahedra and BO{sub 3} groups, which incorporates Li{sup +} ions in channels along the b-axis. In this paper, the synthesis, the crystal structure, and the properties of HP-LiB{sub 3}O{sub 5} are described. Highlights: > Synthesis of a new lithium borate with the composition HP-LiB{sub 3}O{sub 5} at high pressure. > In contrast to the non-centrosymmetric phase LiB{sub 3}O{sub 5}, this high-pressure phase is centrosymmetric. > First example of ternary alkali borates exhibiting threefold bridging oxygen atoms.

  12. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  13. The crystal structure, thermal behaviour and ionic conductivity of a novel lithium gadolinium polyphosphate LiGd(PO{sub 3}){sub 4}

    SciTech Connect

    Ettis, Hasna; Naili, Houcine . E-mail: houcine_naili@yahoo.com; Mhiri, Tahar

    2006-10-15

    Crystal structure and ionic conductivity of lithium gadolinium polyphosphate, LiGd(PO{sub 3}){sub 4}, were investigated. Single crystals of the title compound have been grown by a flux technique. The structure of this novel phosphate was determined by single crystal X-ray diffraction techniques. LiGd(PO{sub 3}){sub 4} is isotypic with LiNd(PO{sub 3}){sub 4}. It crystallizes in the monoclinic space group C2/c with the unit cell parameters a=16.386(2), b=7.059(3), c=9.677(2) A, {beta}=126.12(1){sup o}, V=904.2(4) A{sup 3} and Z=4. The structure refined from 967 independent reflections leads to R {sub 1}=0.0167 and wR {sub 2}=0.0458. The lattice of LiGd(PO{sub 3}){sub 4} is built of twisted zig-zag chains running along with the b direction and make up of PO{sub 4} tetrahedra sharing two corners, connected to the GdO{sub 8} and LiO{sub 4} polyhedra by common oxygen atoms to form a three-dimensional framework. Differential and thermogravimetric thermal analysis are given. The thermal curve of this compound was recorded and interpreted in agreement with impedance measurements. The ionic conductivity has been measured on pellet of the polycrystalline powder and evaluated as a function of temperature. This phase showed the conductivity of 2x10{sup -6} and 2x10{sup -4} {omega}{sup -1} cm{sup -1} at 682 and 951 K, respectively. - Graphical abstract: The structural arrangement of LiGd(PO{sub 3}){sub 4} viewed in the (0 1 0) plane.

  14. Crystal structure of [bis-(2,6-diiso-propyl-phen-yl) phosphato-κO]tris-(methanol-κO)lithium methanol monosolvate.

    PubMed

    Minyaev, Mikhail E; Nifant'ev, Ilya E; Tavtorkin, Alexander N; Korchagina, Sof'ya A; Zeynalova, Shadana Sh

    2015-05-01

    Crystals of the title compound, [Li{OOP(O-2,6-(i)Pr2C6H3)2}(CH3OH)3]·CH3OH or [Li(C24H34O4P)(CH3OH)3]·CH3OH, have been formed in the reaction between HOOP(O-2,6-(i)Pr2C6H3)2 and LiOH in methanol. The title compound is of inter-est as it represents the first reported crystal structure of the family of lithium phosphate diesters. The {Li(CH3OH)3[O2P(O-(i)Pr2C6H3)2]} unit displays the Li atom in a slightly distorted tetra-hedral coordination environment and exhibits one intra-molecular O-H⋯O hydrogen bond between a coordinating methanol mol-ecule and the terminal non-coordinating O atom of the phosphate group. The unit is connected with two non-coordinating methanol mol-ecules through two inter-molecular O-H⋯O hydrogen bonds, and with a neighbouring unit through two other O-H⋯O inter-actions. These inter-molecular hydrogen bonds lead to the formation of infinite chains along [100]. There are no significant inter-actions between the chains.

  15. Accurate determination of the anisotropy factors and the phase differences of Raman polarizabilities in some uniaxial crystals: the case of lithium niobate.

    PubMed

    Djiedeu, N; Mohamadou, B; Bourson, P; Aillerie, M

    2009-01-01

    The present study highlights self-consistently helpful improvements dedicated to overcoming the difficulty resulting from the fitting procedure of integrated Raman intensities recorded according to the rotation crystal method described earlier. To this end, the anisotropy factors of Raman polarizabilities and the corresponding relative phases are determined within the framework of the exact mathematical derivation of the phase factors. These are the relevant parameters of the Raman efficiency relations which are numerically difficult to obtain from the fitting of the integrated areas. The present theoretical approach is then applied to the modes of the A(1) and Ey symmetry species of the lithium niobate (LN) crystal point group. All the expressions of the Raman absolute intensities of the A(1) and Ey irreducible representations initially imply three parameters to be determined from the fitting computations. However, from the derived analytical expressions of the phase differences, the number of parameters involved in the fitting procedure is reduced from 3 to 2, thus improving the statistics of the numerical treatment.

  16. Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor.

    PubMed

    Aldaco, R; Garea, A; Irabien, A

    2007-02-01

    In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.

  17. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method

    SciTech Connect

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-02-05

    Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

  18. Solvothermal indium fluoride chemistry: Syntheses and crystal structures of K{sub 5}In{sub 3}F{sub 14}, beta-(NH{sub 4}){sub 3}InF{sub 6} and [NH{sub 4}]{sub 3}[C{sub 6}H{sub 21}N{sub 4}]{sub 2}[In{sub 4}F{sub 21}

    SciTech Connect

    Jayasundera, Anil C.A.; Goff, Richard J.; Li Yang; Finch, Adrian A.; Lightfoot, Philip

    2010-02-15

    The solvothermal syntheses and crystal structures of three indium fluorides are presented. K{sub 5}In{sub 3}F{sub 14} (1) and beta-(NH{sub 4}){sub 3}InF{sub 6} (2) are variants on known inorganic structure types chiolite and cryolite, respectively, with the latter exhibiting a complex and apparently novel structural distortion. [NH{sub 4}]{sub 3}[C{sub 6}H{sub 21}N{sub 4}]{sub 2}[In{sub 4}F{sub 21}] (3) represents a new hybrid composition displaying a unique trimeric metal fluoride building unit. - Graphical abstract: Solvothermal synthesis has been used to prepare three indium fluorides, including a novel hybrid material containing a unique [In{sub 3}F{sub 15}] trimer templated by tren.

  19. Containerless processing of fluoride glass

    NASA Technical Reports Server (NTRS)

    Doremus, Robert H.

    1990-01-01

    Ground-based experiments on glass formation, crystallization, surface tension, vaporization, and chemical durability of a zirconium-barium-lanthanum (ZBL) fluoride glass are summarized. In a container large, columnar grains grew out from the container-glass interface during cooling. The main crystalline phase was alpha BaZrF6. A ZBL glass sphere was levitated acoustically during Shuttle flight STS-11. The glass was melted and then cooled while being levitated (containerless). Crystallization in the recovered sample was very fine and mainly beta BaZr2F10, showing the influence of the container on the nucleation and microstructure of crystallization in the glass. Glass formation should be easier for a containerless glass than in a container.

  20. Crystal structure of bis­(propane-1,3-di­ammonium) hexa­fluorido­aluminate fluoride trihydrate

    PubMed Central

    Abdi, I.; Al-Sadhan, K. A.; Ben Ali, A.

    2014-01-01

    The title compound, (C3H10N2)2[AlF6]F·3H2O, was obtained using the solvothermal method with aluminium hydroxide, HF and propane-1,3-di­amine as precursors in ethanol as solvent. The structure consists of isolated [AlF6]3− octa­hedra, diprotonated propane-1,3-di­amine cations [(H2dap)2+], free fluoride ions and water mol­ecules of solvation. The Al—F bond lengths in the octa­hedral [AlF6]3− anions range from 1.7690 (19) to 1.8130 (19) Å, with an average value of 1.794 Å. Each [AlF6]3− anion is surrounded by three water mol­ecules and by six diprotonated amine cations. The ‘free’ fluoride ion is hydrogen bonded to four H atoms belonging to four dications and has a distorted tetra­hedral geometry. The three water mol­ecules are connected by hydrogen bonds, forming trimers that connect the AlF6 octa­hedra and dications into a three-dimensional framework. PMID:25309188

  1. Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

    NASA Astrophysics Data System (ADS)

    Komori, Yuichi; Ishii, Yukihiro

    2010-08-01

    A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

  2. Impact of crystal structure singularity on transport and electrochemical properties of Lix(LiyFezV1‑y‑z)O2 — electrode material for lithium batteries

    NASA Astrophysics Data System (ADS)

    Gędziorowski, Bartłomiej; Tobola, Janusz; Braun, Artur; Molenda, Janina

    2016-07-01

    Lithium vanadium oxide (LiVO2) and its substituted derivatives are a distinctive group of materials that may act both, as cathode and anode materials for Li-ion batteries. This paper presents influence of crystal structure singularity of Li(LiyFezV1‑y‑z)O2 (y=0, 0.03, 0.07, z=0, 0.05, 0.1) on transport and electrochemical properties of the compounds.

  3. Preferential growth orientation of laser-patterned LiNbO{sub 3} crystals in lithium niobium silicate glass

    SciTech Connect

    Komatsu, T.; Koshiba, K.; Honma, T.

    2011-02-15

    Dots and lines consisting of LiNbO{sub 3} crystals are patterned on the surface of 1CuO-40Li{sub 2}O-32Nb{sub 2}O{sub 5}-28SiO{sub 2} (mole ratio) glass by irradiations of continuous-wave Nd:YAG laser (wavelength: {lambda}=1064 nm), diode laser ({lambda}=795 nm), and Yb:YVO{sub 4} fiber laser ({lambda}=1080 nm), and the feature of laser-patterned LiNbO{sub 3} crystal growth is examined from linearly polarized micro-Raman scattering spectrum measurements. LiNbO{sub 3} crystals with the c-axis orientation are formed at the edge parts of the surface and cross-section of dots. The growth direction of an LiNbO{sub 3} along the laser scanning direction is the c-axis. It is proposed that the profile of the temperature distribution in the laser-irradiated region and its change along laser scanning would be one of the most important conditions for the patterning of crystals with a preferential growth orientation. Laser irradiation giving a narrow width is also proposed to be one of the important factors for the patterning of LiNbO{sub 3} crystal lines with homogeneous surface morphologies. -- Graphical abstract: Polarized optical microscope observations for the surface and cross-section of the dot obtained by LD laser ({lambda}=795 nm) irradiations of P=1.4 W and t=20 s in Cu-LNS glass. Schematic model for the orientation of LiNbO{sub 3} crystals at the edge parts of the surface and cross-section of the dot is also shown. Display Omitted Research highlights: > Dots and lines with LiNbO{sub 3} crystals are patterned on the glass surface by laser irradiations. > LiNbO{sub 3} crystals with the c-axis orientation are formed at the edge parts of the surface and cross-section of dots. > The profile of the temperature distribution in the laser-irradiated region is one of the most important conditions for the patterning of highly oriented crystals.

  4. Fluoride and Oral Health.

    PubMed

    O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

  5. Fluoride and Oral Health.

    PubMed

    O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature. PMID:27352462

  6. Structural and photoluminescence studies on europium-doped lithium tetraborate (Eu:Li2B4O7) single crystal grown by microtube Czochralski (μT-Cz) technique

    NASA Astrophysics Data System (ADS)

    A, Kumaresh; R, Arun Kumar; N, Ravikumar; U, Madhusoodanan; B, S. Panigrahi; K, Marimuthu; M, Anuradha

    2016-05-01

    Rare earth europium (Eu3+)-doped lithium tetraborate (Eu:Li2B4O7) crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique (μT-Cz) for the first time. The grown crystals are subjected to powder x-ray diffraction (PXRD) analysis which reveals the tetragonal crystal structure of the crystals. UV–vis–NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO3 and BO4 bonding structure and the molecular associations are analyzed by Fourier transform infrared (FTIR) spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate (LTB) single crystal reveal that the observations of peaks at 258, 297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra. The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931 (Commission International d’Eclairage) color chromaticity diagram. Project supported by the Department of Science and Technology–Science and Engineering Research Board (Grant No. SR/S2/LOP-0012/2011), the Government of India for Awarding Major Research Project, the University Grants Commission–Department of Atomic Research–Consortium for Scientific Research (Grant No. CSR–KN/CSR–63/2014–2015/503), and the Kalpakkam and Indore, India.

  7. Structural and photoluminescence studies on europium-doped lithium tetraborate (Eu:Li2B4O7) single crystal grown by microtube Czochralski (μT-Cz) technique

    NASA Astrophysics Data System (ADS)

    A, Kumaresh; R, Arun Kumar; N, Ravikumar; U, Madhusoodanan; B, S. Panigrahi; K, Marimuthu; M, Anuradha

    2016-05-01

    Rare earth europium (Eu3+)-doped lithium tetraborate (Eu:Li2B4O7) crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique (μT-Cz) for the first time. The grown crystals are subjected to powder x-ray diffraction (PXRD) analysis which reveals the tetragonal crystal structure of the crystals. UV-vis-NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO3 and BO4 bonding structure and the molecular associations are analyzed by Fourier transform infrared (FTIR) spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate (LTB) single crystal reveal that the observations of peaks at 258, 297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra. The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931 (Commission International d’Eclairage) color chromaticity diagram. Project supported by the Department of Science and Technology-Science and Engineering Research Board (Grant No. SR/S2/LOP-0012/2011), the Government of India for Awarding Major Research Project, the University Grants Commission-Department of Atomic Research-Consortium for Scientific Research (Grant No. CSR-KN/CSR-63/2014-2015/503), and the Kalpakkam and Indore, India.

  8. Ionic conductivity in single-crystal LiAlSi2O6: influence of structure on lithium mobility

    NASA Astrophysics Data System (ADS)

    Welsch, A.-M.; Murawski, D.; Prekajski, M.; Vulic, P.; Kremenovic, A.

    2015-05-01

    With the increased interest in application of Li aluminosilicate materials as solid electrolytes, this study focuses on investigating the influence of structure on conductivity properties in single-crystal LiAlSi2O6 which is characterized by three crystal polymorphs where only structural arrangements differ while the amount of mobile carriers is identical. Two single-crystal polymorphic phases produced at ambient pressure are with tetragonal P41212 symmetry and hexagonal P6222 symmetry, also referred to as β- and γ-spodumene in the older literature. For this study, flux-grown hexagonal spodumene single-crystals were measured for conductivity parallel to the crystallographic c-axis and the results were compared with previously published results for tetragonal spodumene, both as single-crystal and polycrystalline aggregate, monoclinic spodumene ( α-spodumene) and LiAlSi2O6 glass. The activation energy E a of 79.69 ± 0.38 kJ/mol for hexagonal phase is very similar to the other crystalline polymorphs with the same orientation. However, the σ DC in hexagonal spodumene was determined to be higher than other crystalline phases and about 1.5 orders of magnitude lower than the conductivity in glass LiAlSi2O6 phase. Additionally, the densities of atomic packing were compared between phases, and the differences in the openness of the structures indicate that the more dominant effect on the Li mobility lies with the actual spatial arrangement of Li sites and the Si/Al sublattice.

  9. Characterization of pore and crystal structure of synthesized LiBOB with varying quality of raw materials as electrolyte for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Lestariningsih, Titik; Ratri, Christin Rina; Wigayati, Etty Marty; Sabrina, Qolby

    2016-02-01

    Characterization of pore structure and crystal structure of the LiB(C2O4)2H2O or LIBOB compound has been performed in this study. These recent years, research regarding LiBOB electrolyte salt have been performed using analytical-grade raw materials, therefore this research was aimed to synthesized LiBOB electrolyte salt using the cheaper and abundant technical-grade raw materials. Lithium hydroxide (LiOH), oxalic acid dihydrate (H2C2O4.2H2O), and boric acid (H3BO3) both in technical-grade and analytical-grade quality were used as raw materials for the synthesis of LiBOB. Crystal structure characterization results of synthesized LiBOB from both technical-grade and analytical-grade raw materials have shown the existence of LiBOB and LiBOB hydrate phase with orthorombic structure. These results were also confirmed by FT-IR analysis, which showed the functional groups of LiBOB compounds. SEM analysis results showed that synthesized LiBOB has spherical structure, while commercial LiBOB has cylindrical structure. Synthesized LiBOB has a similar pore size of commercial LiBOB, i.e. 19 nm (mesoporous material). Surface area of synthesized LiBOB from analytical-grade raw materials and technical-grade materials as well as commercial LIBOB were 88.556 m2/g, 41.524 m2/g, and 108.776 m2/g, respectively. EIS analysis results showed that synthesized LiBOB from technical-grade raw materials has lower conductivity than synthesized LiBOB from analytical-grade raw materials.

  10. A theoretical study on the second-order nonlinear optical susceptibilities of lithium formate monohydrate crystal, HCOOLi·H 2O

    NASA Astrophysics Data System (ADS)

    Mang, Chaoyong; Wu, Kechen; Lin, Chensheng; Sa, Rongjian; Liu, Ping; Zhuang, Botao

    2003-06-01

    Ab initio calculations of the first hyperpolarizabilities of (HCOOLi·H 2O) 2 n supermolecules, as the building-blocks of lithium formate monohydrate (LFM) crystal with extended system, were performed for the first time. The dependence of the static βijk0 values on chain length was explored, and the frequency dependence of βijk(-2 ω; ω, ω) was measured, and the influences of electron correlation and basis set on βijk0 were evaluated. Finally, we predicted the second-order nonlinear optical coefficients of LFM crystal. The βijk0 value of (HCOOLi·H 2O) 2 n is linearly dependent on the chain length of supermolecule, which is quite unusual for an extended system connected by the O-Li bonds with ionic characters. Although the static component of βzzz0 tensor is the static largest in these three components under study, the absolute value of frequency-dependent βzyy(-2 ω; ω, ω) element, transforming the smallest into the largest, is the most sensitive to frequency. After the fundamental wavelength is smaller than 500 nm, it is found that the βijk(-2 ω; ω, ω) value is resonantly enhanced to a great extent due to the double frequency lies in the region of resonance. In addition, the βzxx0 value goes from negative to positive with changes of electron correlation and basis set. Obviously, it is very necessary to take into account the effect of electron correlation, if the hyperpolarizability tensor components must be accurately calculated. Moreover, it is also very important whether it is adopted a complete basis set with diffuse and polarization functions. The calculated nonlinear coefficients at high level suggest that the scaled set reported by Robert seem more reasonable.

  11. Refinement of the crystal structure of calcium-lithium-aluminum tourmaline from the pegmatite vein in the Sangilen Upland (Tuva Republic)

    SciTech Connect

    Rozhdestvenskaya, I. V. Bronzova, Yu. M.; Frank-Kamenetskaya, O. V.; Zolotarev, A. A.; Kuznetsova, L. G.; Bannova, I. I.

    2008-03-15

    The crystal structure of a natural calcium-lithium-aluminum tourmaline, which has the unique composition (Ca{sub 0.62}Na{sub 0.32}{open_square}{sub 0.06})(Al{sub 1.08}Li{sub 0.99}Fe{sub 0.66}{sup 2+} Mg{sub 0.24}Ti{sub 0.03})Al{sub 6}[Si{sub 6}O{sub 18}](BO{sub 3}){sub 3}(OH{sub 2.28}O{sub 0.72}) {center_dot} (F{sub 0.84}O{sub 0.16}), is refined (R = 0.019, R{sub w} = 0.022, S = 1.47). It is found that the O(1)(W) site is split into two sites, O(1) and O(11), which are incompletely occupied by fluorine and oxygen anions, respectively, and that the O(3)(V) site contains bivalent oxygen anions. The solid solution studied is close in composition to the liddicoatite mineral species and differs from the latter one by the Li: Al ratio in the Y octahedra and the presence of bivalent oxygen anions in the O(3) site. The tourmaline studied differs from the hypothetical oxyliddicoatite by the population of the O(1)(W) site by fluorine and accommodation of additional oxygen anions in the O(3)(V) site.

  12. Refinement of the crystal structure of calcium-lithium-aluminum tourmaline from the pegmatite vein in the Sangilen Upland (Tuva Republic)

    SciTech Connect

    Rozhdestvenskaya, I. V. Bronzova, Yu. M.; Frank-Kamenetskaya, O. V.; Zolotarev, A. A.; Kuznetsova, L. G.; Bannova, I. I.

    2008-03-15

    The crystal structure of a natural calcium-lithium-aluminum tourmaline, which has the unique composition (Ca{sub 0.62}Na{sub 0.32}{open_square}{sub 0.06})(Al{sub 1.08}Li{sub 0.99}Fe{sub 0.66}{sup 2+} Mg{sub 0.24}Ti{sub 0.03})Al{sub 6}[Si{sub 6}O{sub 18}](BO{sub 3}){sub 3}(OH{sub 2.28}O{sub 0.72}) . (F{sub 0.84}O{sub 0.16}), is refined (R = 0.019, R{sub w} = 0.022, S = 1.47). It is found that the O(1)(W) site is split into two sites, O(1) and O(11), which are incompletely occupied by fluorine and oxygen anions, respectively, and that the O(3)(V) site contains bivalent oxygen anions. The solid solution studied is close in composition to the liddicoatite mineral species and differs from the latter one by the Li: Al ratio in the Y octahedra and the presence of bivalent oxygen anions in the O(3) site. The tourmaline studied differs from the hypothetical oxyliddicoatite by the population of the O(1)(W) site by fluorine and accommodation of additional oxygen anions in the O(3)(V) site.

  13. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  14. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  15. The Effect of Crystal Face of Fe2O3 on the Electrochemical Performance for Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Chen, Minmin; Zhao, Enyue; Yan, Qingbo; Hu, Zhongbo; Xiao, Xiaoling; Chen, Dongfeng

    2016-07-01

    Fe2O3 nanorods exposing (001) and (010) plane as well as Fe2O3 nanosheets exposing (001) plane have been successfully synthesized. Fe2O3 nanosheets exhibit better cycle performance and rate capabilities than that of Fe2O3 nanorods. The discharge capacity of Fe2O3 nanosheets can stabilize at 865 mAh/g at the rate of 0.2 C (1C = 1000 mA/g) and 570 mAh/g at the rate of 1.2 C after 80 cycles, which increased by 90% and 79% compared with 456 mAh/g and 318 mAh/g of Fe2O3 nanorods. In comparison with (010) plane, the (001) plane of hematite possesses larger packing density of Fe3+ and O2-, which is responsible for the superior electrochemical performances of Fe2O3 nanosheets than that of Fe2O3 nanorods. In addition, potentiostatic intermittent titration (PITT) results show the diffusion coefficients of Li+ (DLi) of Fe2O3 nanosheets is higher than that of Fe2O3 nanorods. The higher diffusion coefficients of Li+ is favorable for the excellent lithium-storage capabilities and rate capability of Fe2O3 nanosheets. Inspired by our results, we can design and synthesize Fe2O3 or other electrodes with high performances according to their structure features in future.

  16. The Effect of Crystal Face of Fe2O3 on the Electrochemical Performance for Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Chen, Minmin; Zhao, Enyue; Yan, Qingbo; Hu, Zhongbo; Xiao, Xiaoling; Chen, Dongfeng

    2016-07-01

    Fe2O3 nanorods exposing (001) and (010) plane as well as Fe2O3 nanosheets exposing (001) plane have been successfully synthesized. Fe2O3 nanosheets exhibit better cycle performance and rate capabilities than that of Fe2O3 nanorods. The discharge capacity of Fe2O3 nanosheets can stabilize at 865 mAh/g at the rate of 0.2 C (1C = 1000 mA/g) and 570 mAh/g at the rate of 1.2 C after 80 cycles, which increased by 90% and 79% compared with 456 mAh/g and 318 mAh/g of Fe2O3 nanorods. In comparison with (010) plane, the (001) plane of hematite possesses larger packing density of Fe3+ and O2‑, which is responsible for the superior electrochemical performances of Fe2O3 nanosheets than that of Fe2O3 nanorods. In addition, potentiostatic intermittent titration (PITT) results show the diffusion coefficients of Li+ (DLi) of Fe2O3 nanosheets is higher than that of Fe2O3 nanorods. The higher diffusion coefficients of Li+ is favorable for the excellent lithium-storage capabilities and rate capability of Fe2O3 nanosheets. Inspired by our results, we can design and synthesize Fe2O3 or other electrodes with high performances according to their structure features in future.

  17. The Effect of Crystal Face of Fe2O3 on the Electrochemical Performance for Lithium-ion Batteries

    PubMed Central

    Chen, Minmin; Zhao, Enyue; Yan, Qingbo; Hu, Zhongbo; Xiao, Xiaoling; Chen, Dongfeng

    2016-01-01

    Fe2O3 nanorods exposing (001) and (010) plane as well as Fe2O3 nanosheets exposing (001) plane have been successfully synthesized. Fe2O3 nanosheets exhibit better cycle performance and rate capabilities than that of Fe2O3 nanorods. The discharge capacity of Fe2O3 nanosheets can stabilize at 865 mAh/g at the rate of 0.2 C (1C = 1000 mA/g) and 570 mAh/g at the rate of 1.2 C after 80 cycles, which increased by 90% and 79% compared with 456 mAh/g and 318 mAh/g of Fe2O3 nanorods. In comparison with (010) plane, the (001) plane of hematite possesses larger packing density of Fe3+ and O2−, which is responsible for the superior electrochemical performances of Fe2O3 nanosheets than that of Fe2O3 nanorods. In addition, potentiostatic intermittent titration (PITT) results show the diffusion coefficients of Li+ (DLi) of Fe2O3 nanosheets is higher than that of Fe2O3 nanorods. The higher diffusion coefficients of Li+ is favorable for the excellent lithium-storage capabilities and rate capability of Fe2O3 nanosheets. Inspired by our results, we can design and synthesize Fe2O3 or other electrodes with high performances according to their structure features in future. PMID:27380891

  18. Effects of Gravity on Processing Heavy Metal Fluoride Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

    1997-01-01

    The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

  19. Laser Crystal

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Lightning Optical Corporation, under an SBIR (Small Business Innovative Research) agreement with Langley Research Center, manufactures oxide and fluoride laser gain crystals, as well as various nonlinear materials. The ultimate result of this research program is the commercial availability in the marketplace of a reliable source of high-quality, damage resistant laser material, primarily for diode-pumping applications.

  20. Crystal Structures of Beryllium Fluoride-Free and Beryllium Fluoride-Bound CheY in Complex with the Conserved C-Terminal Peptide of CheZ Reveal Dual Binding Modes Specific to CheY Conformation

    SciTech Connect

    Guhaniyogi,J.; Robinson, V.; Stock, A.

    2006-01-01

    Chemotaxis, the environment-specific swimming behavior of a bacterial cell is controlled by flagellar rotation. The steady-state level of the phosphorylated or activated form of the response regulator CheY dictates the direction of flagellar rotation. CheY phosphorylation is regulated by a fine equilibrium of three phosphotransfer activities: phosphorylation by the kinase CheA, its auto-dephosphorylation and dephosphorylation by its phosphatase CheZ. Efficient dephosphorylation of CheY by CheZ requires two spatially distinct protein-protein contacts: tethering of the two proteins to each other and formation of an active site for dephosphorylation. The former involves interaction of phosphorylated CheY with the small highly conserved C-terminal helix of CheZ (CheZ{sub C}), an indispensable structural component of the functional CheZ protein. To understand how the CheZ{sub C} helix, representing less than 10% of the full-length protein, ascertains molecular specificity of binding to CheY, we have determined crystal structures of CheY in complex with a synthetic peptide corresponding to 15 C-terminal residues of CheZ (CheZ{sub 200-214}) at resolutions ranging from 2.0 Angstroms to 2.3 Angstroms. These structures provide a detailed view of the CheZC peptide interaction both in the presence and absence of the phosphoryl analog, BeF{sub 3}{sup -}. Our studies reveal that two different modes of binding the CheZ{sub 200-214} peptide are dictated by the conformational state of CheY in the complex. Our structures suggest that the CheZ{sub C} helix binds to a 'meta-active' conformation of inactive CheY and it does so in an orientation that is distinct from the one in which it binds activated CheY. Our dual binding mode hypothesis provides implications for reverse information flow in CheY and extends previous observations on inherent resilience in CheY-like signaling domains.

  1. Crystal Structures of Beryllium Fluoride-Free and Beryllium Fluoride-Bound CheY in Complex with the Conserved C-Terminal Peptide of CheZ Reveal Dual Binding Modes Specific to CheY Conformation

    PubMed Central

    Guhaniyogi, Jayita; Robinson, Victoria L.; Stock, Ann M.

    2013-01-01

    Summary Chemotaxis, the environment-specific swimming behavior of a bacterial cell is controlled by flagellar rotation. The steady-state level of the phosphorylated or activated form of the response regulator CheY dictates the direction of flagellar rotation. CheY phosphorylation is regulated by a fine equilibrium of three phosphotransfer activities: phosphorylation by the kinase CheA, its auto-dephosphorylation and dephosphorylation by its phosphatase CheZ. Efficient dephosphorylation of CheY by CheZ requires two spatially distinct protein-protein contacts: tethering of the two proteins to each other and formation of an active site for dephosphorylation. The latter involves interaction of phosphorylated CheY with the small highly conserved C-terminal helix of CheZ (CheZC), an indispensable structural component of the functional CheZ protein. To understand how the CheZC helix, representing less than 1% of the full-length protein, ascertains molecular specificity of binding to CheY, we have determined crystal structures of CheY in complex with a synthetic peptide corresponding to 15 C-terminal residues of CheZ (CheZ200-214) at resolutions ranging from 2.0 Å to 2.3 Å. These structures provide a detailed view of the CheZC peptide interaction both in the presence and absence of the phosphoryl analog, BeF3−. Our studies reveal that two different modes of binding the CheZ200-214 peptide are dictated by the conformational state of CheY in the complex. Our structures suggest that the CheZC helix binds to a “meta-active” conformation of inactive CheY and it does so in an orientation that is distinct from the one in which it binds activated CheY. Our dual binding mode hypothesis provides implications for reverse information flow in CheY and extends previous observations on inherent resilience in CheY-like signaling domains. PMID:16674976

  2. PRODUCTION OF THORIUM FLUORIDE

    DOEpatents

    Zachariasen, W.H.

    1959-08-11

    A process is presented for producing anhydrous thorium fluoride comprising the step of contacting a saturated aqueous solution of thorium nitrate with an aqueous solution of hydrofluoric acid having a concentration of about 45 to 50% by weight at a temperature above 70 deg C whereby anhydrous thorium fluoride precipitates.

  3. Controlled synthesis of series NixCo3-xO4 products: Morphological evolution towards quasi-single-crystal structure for high-performance and stable lithium-ion batteries

    PubMed Central

    Zhou, Yu; Liu, Yong; Zhao, Wenxia; Wang, Hai; Li, Baojun; Zhou, Xiang; Shen, Hui

    2015-01-01

    Transition metal oxides are very promising alternative anode materials for high-performance lithium-ion batteries (LIBs). However, their conversion reactions and concomitant volume expansion cause the pulverization, leading to poor cycling stability, which limit their applications. Here, we present the quasi-single-crystal NixCo3-xO4 hexagonal microtube (QNHM) composed of continuously twinned single crystal submicron-cubes as anode materials for LIBs with high energy density and long cycle life. At the current density of 0.8 A g−1, it can deliver a high discharge capacities of 1470 mAh g−1 over 100 cycles (105% of the 2nd cycle) and 590 mAh g−1 even after 1000 cycles. To better understand what underlying factors lead our QNHMs to achieve excellent electrochemical performance, a series of NixCo3-xO4 products with systematic shape evolution from spherical to polyhedral, and cubic particles as well as circular microtubes consisted of spheres and square microtubes composed of polyhedra have been synthesized. The excellent electrochemical performance of QNHMs is attributed to the unique stable quasi-single-crystal structure, which can both provide efficient electrical transport pathway and suppress the electrode pulverization. It is important to note that such quasi-single-crystal structure would be helpful to explore other high-energy lithium storage materials based on alloying or conversion reactions. PMID:26103885

  4. Controlled synthesis of series NixCo3-xO4 products: Morphological evolution towards quasi-single-crystal structure for high-performance and stable lithium-ion batteries.

    PubMed

    Zhou, Yu; Liu, Yong; Zhao, Wenxia; Wang, Hai; Li, Baojun; Zhou, Xiang; Shen, Hui

    2015-06-24

    Transition metal oxides are very promising alternative anode materials for high-performance lithium-ion batteries (LIBs). However, their conversion reactions and concomitant volume expansion cause the pulverization, leading to poor cycling stability, which limit their applications. Here, we present the quasi-single-crystal Ni(x)Co(3-x)O4 hexagonal microtube (QNHM) composed of continuously twinned single crystal submicron-cubes as anode materials for LIBs with high energy density and long cycle life. At the current density of 0.8 A g(-1), it can deliver a high discharge capacities of 1470 mAh g(-1) over 100 cycles (105% of the 2nd cycle) and 590 mAh g(-1) even after 1000 cycles. To better understand what underlying factors lead our QNHMs to achieve excellent electrochemical performance, a series of Ni(x)Co(3-x)O4 products with systematic shape evolution from spherical to polyhedral, and cubic particles as well as circular microtubes consisted of spheres and square microtubes composed of polyhedra have been synthesized. The excellent electrochemical performance of QNHMs is attributed to the unique stable quasi-single-crystal structure, which can both provide efficient electrical transport pathway and suppress the electrode pulverization. It is important to note that such quasi-single-crystal structure would be helpful to explore other high-energy lithium storage materials based on alloying or conversion reactions.

  5. MAS-NMR investigations of the crystallization behaviour of lithium aluminum silicate (LAS) glasses containing P{sub 2}O{sub 5} and TiO{sub 2} nucleants

    SciTech Connect

    Ananthanarayanan, A.; Kothiyal, G.P.; Montagne, L.; Revel, B.

    2010-06-15

    Lithium aluminum silicate (LAS) glass of composition (mol%) 20.4Li{sub 2}O-4.0Al{sub 2}O{sub 3}-68.6SiO{sub 2}-3.0K{sub 2}O-2.6B{sub 2}O{sub 3}-0.5P{sub 2}O{sub 5}-0.9TiO{sub 2} was prepared by melt quenching. The glass was then nucleated and crystallized based on differential thermal analysis (DTA) data and was characterized by {sup 29}Si, {sup 31}P, {sup 11}B and {sup 27}Al MAS-NMR. XRD and {sup 29}Si NMR showed that lithium metasilicate (Li{sub 2}SiO{sub 3}) is the first phase to c form followed by cristobalite (SiO{sub 2}) and lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}). {sup 29}Si MAS-NMR revealed a change in the network structure already for the glasses nucleated at 550 {sup o}C. Since crystalline Li{sub 3}PO{sub 4}, as observed by {sup 31}P MAS-NMR, forms concurrently with the silicate phases, we conclude that crystalline Li{sub 3}PO{sub 4} does not act as a nucleating agent for lithium silicate phases. Moreover, {sup 31}P NMR indicates the formation of M-PO{sub 4} (M=B, Al or Ti) complexes. The presence of BO{sub 3} and BO{sub 4} structural units in all the glass/glass-ceramic samples is revealed through {sup 11}B MAS-NMR. B remains in the residual glass and the crystallization of silicate phases causes a reduction in the number of alkali ions available for charge compensation. As a result, the number of trigonally coordinated B (BO{sub 3}) increases at the expense of tetrahedrally coordinated B (BO{sub 4}). The {sup 27}Al MAS-NMR spectra indicate the presence of tetrahedrally coordinated Al species, which are only slightly perturbed by the crystallization. - Graphical abstract: {sup 11}B MAS-NMR spectra of LAS glass heat treated at different temperatures, showing the evolution of the residual glass matrix during the crystallization treatment. High-field (18.8 T) NMR enables us to record high resolution spectra, from which the glass network modifications could be related to the formation of intermediate lithium silicate crystalline phases.

  6. Solid electrolytes for fluoride ion batteries: ionic conductivity in polycrystalline tysonite-type fluorides.

    PubMed

    Rongeat, Carine; Reddy, M Anji; Witter, Raiker; Fichtner, Maximilian

    2014-02-12

    Batteries based on a fluoride shuttle (fluoride ion battery, FIB) can theoretically provide high energy densities and can thus be considered as an interesting alternative to Li-ion batteries. Large improvements are still needed regarding their actual performance, in particular for the ionic conductivity of the solid electrolyte. At the current state of the art, two types of fluoride families can be considered for electrolyte applications: alkaline-earth fluorides having a fluorite-type structure and rare-earth fluorides having a tysonite-type structure. As regard to the latter, high ionic conductivities have been reported for doped LaF3 single crystals. However, polycrystalline materials would be easier to implement in a FIB due to practical reasons in the cell manufacturing. Hence, we have analyzed in detail the ionic conductivity of La(1-y)Ba(y)F(3-y) (0 ≤ y ≤ 0.15) solid solutions prepared by ball milling. The combination of DC and AC conductivity analyses provides a better understanding of the conduction mechanism in tysonite-type fluorides with a blocking effect of the grain boundaries. Heat treatment of the electrolyte material was performed and leads to an improvement of the ionic conductivity. This confirms the detrimental effect of grain boundaries and opens new route for the development of solid electrolytes for FIB with high ionic conductivities. PMID:24444763

  7. Crystal structure of μ-fluorido-bis-{(η(4)-cyclo-octa-diene)[hexa-fluorido-anti-monato(V)]platinum(II)} hexa-fluorido-anti-monate(V) hydrogen fluoride 0.75-solvate.

    PubMed

    Seppelt, Konrad; Friedemann, Roland

    2016-01-01

    In the complex cation of the binuclear solvated title salt, [Pt2F(SbF6)2(C8H12)2]SbF6·0.75HF, an F atom bridges the two platinum(II) atoms with a bond angle of 123.3 (2)°. The corresponding Pt-F bond lengths are in the range of other fluorine-bridged binuclear platinum(II) complexes. Two of the three SbF6 (-) anions each coordinate with one F atom to one platinum(II) atom. Including the η(4)-bound cyclo-octa-diene (COD) ligands, the overall coordination sphere of each platinum(II) atom is square-planar. The third SbF6 (-) anion is not bound to the complex. Hydrogen fluoride is present in the crystal structure as a solvent disordered over three positions, each with an occupancy of 0.25. F⋯F distances of 2.5512 (7), 2.6076 (8) and 3.2215 (10) Å to surrounding SbF6 (-) anions are indicative of F-H⋯F hydrogen-bonding inter-actions although no H atoms could be localized for the disordered solvent mol-ecules. The resulting hydrogen-bonded network is three-dimensional. PMID:26870575

  8. Quantitative determination of lattice fluoride effects on the solubility and crystallinity of carbonated apatites with incorporated fluoride.

    PubMed

    Yan, G; Moribe, K; Otsuka, M; Papangkorn, K; Higuchi, W I

    2013-01-01

    The purpose of this study was to evaluate quantitatively the effects of fluoride on the solubility and crystallinity of carbonated apatites (CAPs) after its incorporation into the crystal lattice using the metastable equilibrium solubility (MES) distribution method. Fluoride-incorporated CAPs (F-CAPs) of two different carbonate levels (3 and 5%) and fluoride contents from 0 to 20,000 µg/g were synthesized. X-ray diffraction experiments and Rietveld analysis were conducted to obtain crystallite microstrain and unit cell parameters. Acetate buffer MES solution media were prepared at two solution fluoride concentrations (0.2 and 2.0 mg/l) and at two pHs (5.0 and 5.7). The unit cell a-axis values of the F-CAPs were found to decrease as the fluoride content increased, consistent with the fluoride being incorporated into the crystal lattice. The fluoride concentrations in the MES solution media were high enough to provide a 'swamping' effect such that the fluoride released from the F-CAPs during dissolution was minimal in changing the solution fluoride concentration. Employing the MES distribution superposition method, it was shown that the surface complex possessing the fluorapatite (FAP) stoichiometry [Ca10(PO4)6F2] accounted for the MES distribution behavior of all experiments. In addition, the mean pIFAP [the value of -log(aCa(10)aPO4(6)aF(2)) calculated from the ionic activity product based on FAP stoichiometry of the MES dissolution media in which 50% of the F-CAPs had dissolved] correlated well with the crystallite microstrain parameters of the F-CAPs. The incorporated fluoride in the F-CAPs showed only modest effects on F-CAP crystallinity and solubility.

  9. Hydrolysis of iron and chromium fluorides: mechanism and kinetics.

    PubMed

    Gálvez, José L; Dufour, Javier; Negro, Carlos; López-Mateos, Federico

    2008-06-15

    Fluoride complexes of metallic ions are one of the main problems when processing industrial effluents with high content of fluoride anion. The most important case is derived from pickling treatment of stainless steel, which is performed with HNO3/HF mixtures to remove oxides scale formed over the metal surface. Waste from this process, spent pickling liquor, must be treated for recovering metallic and acid content. Conventional treatments produce a final effluent with high quantity of fluoride complexes of iron and chromium. This work proposes a hydrolysis treatment of these solid metal fluorides by reacting them with a basic agent. Metal oxides are obtained, while fluoride is released to solution as a solved salt, which can be easily recovered as hydrofluoric acid. Solid iron and chromium fluorides, mainly K2FeF5(s) and CrF3(s), obtained in the UCM treatment process, were employed in this work. Optimal hydrolysis operating conditions were obtained by means of a factorial design: media must be basic but pH cannot be higher than 9.5, temperature from 40 to 70 degrees C and alkali concentration (potassium hydroxide) below 1.1 mol L(-1). Secondary reactions have been detected, which are probably due to fluoride adsorption onto obtained oxides surface. Mechanism of reaction consists of several stages, involving solid fluoride dissolution and complexes decomposition. Hydrolysis kinetics has been modeled with classical crystal dissolution kinetics, based on mass transfer phenomena. PMID:17988794

  10. Hydrogen, lithium, and lithium hydride production

    DOEpatents

    Brown, Sam W; Spencer, Larry S; Phillips, Michael R; Powell, G. Louis; Campbell, Peggy J

    2014-03-25

    A method of producing high purity lithium metal is provided, where gaseous-phase lithium metal is extracted from lithium hydride and condensed to form solid high purity lithium metal. The high purity lithium metal may be hydrided to provide high purity lithium hydride.

  11. Surfactant-assisted hydrothermal crystallization of nanostructured lithium metasilicate (Li{sub 2}SiO{sub 3}) hollow spheres: (I) Synthesis, structural and microstructural characterization

    SciTech Connect

    Ortiz-Landeros, J.

    2011-05-15

    Lithium metasilicate (Li{sub 2}SiO{sub 3}) was successfully synthesized using a hydrothermal process in the presence of different surfactants with cationic, non-ionic and anionic characters. The samples obtained were compared to a sample prepared by the conventional solid-state reaction method. The structural and microstructural characterizations of different Li{sub 2}SiO{sub 3} powders were performed using various techniques. Diffraction analyses revealed the successful crystallization of pure Li{sub 2}SiO{sub 3} single phase by hydrothermal technique, even without further heat-treatments and independent of the surfactant used. Electron microscopy analyses revealed that Li{sub 2}SiO{sub 3} powders were composed of uniform micrometric particles with a hollow sphere morphology and nanostructured walls. Finally, different thermal analyses showed that Li{sub 2}SiO{sub 3} samples preserved their structure and microstructure after further thermal treatments. Specific aspects regarding the formation mechanism of the spherical aggregates under hydrothermal conditions are discussed, and there is a special emphasis on the effect of the synthesis pathway on the morphological characteristics. -- Graphical abstract: Li{sub 2}SiO{sub 3} was synthesized using a hydrothermal process in the presence of different surfactants. Li{sub 2}SiO{sub 3} powders were composed of uniform micrometric particles with a hollow sphere morphology and nanostructured walls. Display Omitted Highlights: {yields} Pure Li{sub 2}SiO{sub 3} was synthesized by the hydrothermal method. {yields} Surfactant addition produced microstructural and morphological variations. {yields} TEM reveled the generation of nanostructured hollow spheres.

  12. Growth kinetics of calcium fluoride at high supersaturation in a fluidized bed reactor.

    PubMed

    Jiang, K; Zhou, K G; Yang, Y C; Du, H

    2014-01-01

    Crystallization process in a fluidized bed reactor (FBR) has been regarded as an environmentally friendly technology for the removal and recovery of fluoride from industrial wastewater. The growth kinetics of calcium fluoride at high supersaturation was studied for design, control, and operation of an FBR. The main variables, including supersaturation, superficial velocity, pH value, and particle size of seed that influenced the crystal growth were investigated. Then, a growth model was used to predict the linear growth rate of calcium fluoride at a high influent concentration of fluoride. The pressure difference in the FBR was used as a feature to characterize the growth rate of calcium fluoride. The aggregation and adsorption between seeds and fine particles were proven to be a possible mechanism for growth of calcium fluoride.

  13. Eu{sub 3}F{sub 4}S{sub 2}: Synthesis, crystal structure, and magnetic properties of the mixed-valent europium(II,III) fluoride sulfide EuF{sub 2}.(EuFS){sub 2}

    SciTech Connect

    Grossholz, Hagen; Hartenbach, Ingo; Kotzyba, Gunter; Poettgen, Rainer; Trill, Henning; Mosel, Bernd D.; Schleid, Thomas

    2009-11-15

    Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS (M=Y, La, Ce-Lu), in some cases we were able to obtain mixed-valent compounds such as Yb{sub 3}F{sub 4}S{sub 2} instead. With Eu{sub 3}F{sub 4}S{sub 2} another isotypic representative has now been synthesized. Eu{sub 3}F{sub 4}S{sub 2} (tetragonal, I4/mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 deg. C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an intergrowth structure, in which one layer of CaF{sub 2}-type EuF{sub 2} is followed by two layers of PbFCl-type EuFS when sheeted parallel to the (001) plane. Accordingly there are two chemically and crystallographically different europium cations present. One of them (Eu{sup 2+}) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu{sup 3+}) exhibits a monocapped square antiprismatic coordination sphere with four F{sup -} and five S{sup 2-} anions. Although the structural ordering of the different charged europium cations is plausible, a certain amount of charge delocalization with some polaron activity has to take place, which is suggested by the black color of the title compound. Temperature dependent magnetic susceptibility measurements of Eu{sub 3}F{sub 4}S{sub 2} show Curie-Weiss behavior with an experimental magnetic moment of 8.19(5) mu{sub B} per formula unit and a paramagnetic Curie temperature of 0.3(2) K. No magnetic ordering is observed down to 4.2 K. In accordance with an ionic formula splitting like (Eu{sup II})(Eu{sup III}){sub 2}F{sub 4}S{sub 2} only one third of the europium centers in Eu{sub 3}F{sub 4}S{sub 2} carry permanent

  14. Dosimetric properties of activated lithium tetraborate

    NASA Astrophysics Data System (ADS)

    Majchrowski, Andrzej; Malecki, M.; Zmija, Jozef; Warkocki, Stanislaw; Warkocki, Wodzislaw

    1993-10-01

    This paper describes preliminary investigations of Li2B4O7 thermoluminescent phosphors as candidates for gamma radiation dosimetry materials. Single crystals, glasses, and polycrystals of lithium tetraborate activated with different dopants have been investigated.

  15. Inverse temperature dependence of electrical conductivity of solutions of lithium salts in aprotic media

    SciTech Connect

    Plakhotnik, V.N.; Tovmash, N.F.; Kovtum, Yu.V.

    1987-08-01

    Solutions of lithium salts in aprotic dipolar solvents are studied in this paper for their use as electrolytes in lithium batteries. The temperature dependence and isotherms of the electric conductivity of molten salts of lithium fluorides with arsenic and boron are assessed against a range of solvents including tetrahydrofuran, propylene carbonate, 1,3-dioxolane, gamma-butyrolactone, water, hydrogen, and dimethoxyethane. Ionization potentials are given and molar ratios for the salts and solvents are tabulated.

  16. Fluoride in diet

    MedlinePlus

    ... broken through the gums have changes in the enamel that covers the teeth. Faint white lines or streaks may appear, but ... regarding fluoride intake from reconstituted infant formula and ... Dental Association Council on Scientific Affairs. J Am Dent ...

  17. Synthesis, crystal structure and optical properties of the new lead fluoride borate-Pb{sub 2}BO{sub 3}F

    SciTech Connect

    Zhao Wenwu; Pan Shilie; Han Jian; Yao Jiyong; Yang Yun; Li Junjie; Zhang Min; Zhang Lianhan; Hang Yin

    2011-11-15

    A new compound, Pb{sub 2}BO{sub 3}F, has been grown by high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. The crystal structure of this compound has been identified by single crystal X-ray diffraction analysis. It crystallizes in the hexagonal system, space group P6{sub 3}/m (No. 176) with unit-cell parameters a=7.2460(3) A, c=14.5521(17) A, Z=6, V=661.69(9) A{sup 3}. Its structure was solved by the direct methods and refined to R{sub 1}=0.0163 and wR{sub 2}=0.0367. The structure of Pb{sub 2}BO{sub 3}F consists of the distorted PbO{sub 3}F{sub 2} groups and BO{sub 3} triangles, which are all symmetric with each other in the gestalt structure to the extent that the Pb{sub 2}BO{sub 3}F compound crystallizes in the symmetric space group. The powder X-ray diffraction pattern of the Pb{sub 2}BO{sub 3}F has been measured. The BO{sub 3} functional groups presented in the sample were identified by FTIR spectrum. The DTA curve of Pb{sub 2}BO{sub 3}F suggests that Pb{sub 2}BO{sub 3}F melts congruently at 448 deg. C. - Graphical Abstract: The Pb atoms are in the five coordination environments bonded to three O atoms and two F atoms to make up the distortional PbO{sub 3}F{sub 2} polyhedra. Every six PbO{sub 3}F{sub 2} polyhedra are connected by one F(1) atom to form the symmetrical structure, and then the distortion of the PbO{sub 3}F{sub 2} polyhedra is offset. Highlights: > A new compound, Pb{sub 2}BO{sub 3}F, has been grown by high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. > It crystallizes in the hexagonal system, space group P6{sub 3}/m (No. 176) with unit-cell parameters a=7.2460(3) A, c=14.5521(17) A, Z=6, V=661.69(9) A{sup 3}. > UV-vis-NIR Diffuse-Reflectance spectrum shows that its ultraviolet cutoff edge is about 288 nm. > DTA curve of Pb{sub 2}BO{sub 3}F suggests that Pb{sub 2}BO{sub 3}F melts congruently at 448 deg. C.

  18. Process for converting magnesium fluoride to calcium fluoride

    DOEpatents

    Kreuzmann, A.B.; Palmer, D.A.

    1984-12-21

    This invention is a process for the conversion of magnesium fluoride to calcium fluoride whereby magnesium fluoride is decomposed by heating in the presence of calcium carbonate, calcium oxide or calcium hydroxide. Magnesium fluoride is a by-product of the reduction of uranium tetrafluoride to form uranium metal and has no known commercial use, thus its production creates a significant storage problem. The advantage of this invention is that the quality of calcium fluoride produced is sufficient to be used in the industrial manufacture of anhydrous hydrogen fluoride, steel mill flux or ceramic applications.

  19. Fluorides in the new millennium.

    PubMed

    Padilla, O; Davis, M J

    2001-02-01

    Water fluoridation is known to be the most successful public health measure of the 20th century. More than half a century later, we are still reaping the benefits of fluoridation. We now know that the most important mechanism of fluoride action occurs through daily low-dose exposures. The battle between demineralization and remineralization occurs constantly, and fluoride shifts the balance to the latter. This dynamic, daily process far supersedes the pre-eruptive fluoride incorporation in importance. Fluoride, however, is now available in a variety of very different forms, useful in waging the war on caries. Nevertheless, opponents of this therapeutic agent maintain that its widespread use should be curtailed. Although the benefits of fluoride can no longer be disputed, fluoride supplementation must be supported and approached with consideration of total fluoride exposure. PMID:11280144

  20. Pseudotetragonal structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50): the first mixed valence cerium fluoride.

    PubMed

    Renaudin, Guillaume; Dieudonné, Belto; Avignant, Daniel; Mapemba, Elise; El-Ghozzi, Malika; Fleutot, Solène; Martinez, Hervé; Cerný, Radovan; Dubois, Marc

    2010-01-18

    The crystal structure of the new Li(5.5)Ce(12)F(50) compound has been fully characterized by single-crystal and synchrotron powder X-ray diffraction. An accurate pseudotetragonal structure was described in the monoclinic P2(1) space group with 68 independent crystallographic sites. The Li(5.5)Ce(12)F(50) composition belongs to the Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) solid solution. Its structure consists of an opened fluorine framework where a channel network allows the intercalation of relatively mobile lithium cations, inducing the formation of the mixed-valence cerium (the intercalation of Li(+) leads to the reduction of a part of Ce(4+) to Ce(3+)). One part of the lithium ions, necessary for the electroneutrality of the tetravalent equivalent cerium fluoride (Li(2)Ce(12)F(50) composition), is in a locked fluorine polyhedron. Only the supplementary x amount of lithium is able to be exchanged in Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50). The structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) is a rearrangement, due to lithium intercalation, of the base CeF(4) structure. Bond valence calculation on Ce sites, Ce coordination polyhedra volumes, and a calculated Ce cationic radius give the indication of a partial long-range ordering of trivalent and tetravalent cerium cations in specific slabs of the structure. (7)Li NMR spectroscopy and XPS analyses have confirmed all of the structure details.

  1. The preparation and characterization of iron fluorides polymorphs FeF{sub 3}·0.33H{sub 2}O and β-FeF{sub 3}∙3H{sub 2}O as cathode materials for lithium-ion batteries

    SciTech Connect

    Chen, Chao; Xu, Xiaoping; Chen, Shu; Zheng, Bin; Shui, Miao Xu, Lingxia; Zheng, Weidong; Shu, Jie Cheng, Liangliang; Feng, Lin; Ren, Yuanlong

    2015-04-15

    Graphical abstract: Better rate capability and cycling performance were observed for β-FeF{sub 3}·3H{sub 2}O/C prepared by mechano-chemical synthesis. - Highlights: • A novel mechano-chemical preparation method. • The use of NH{sub 4}F as starting material. • Better electro-chemical performance in the case of β-FeF{sub 3}·3H{sub 2}O/C. - Abstract: Two kinds of iron fluorides, FeF{sub 3}·0.33H{sub 2}O and β-FeF{sub 3}∙3H{sub 2}O, have been synthesized by different chemical routes using Fe(NO{sub 3}){sub 3}·9H{sub 2}O and NH{sub 4}F as precursors and investigated as cathode materials for secondary lithium batteries. β-FeF{sub 3}·3H{sub 2}O was obtained via a mechano-chemical process and FeF{sub 3}·0.33H{sub 2}O was obtained by a precipitation reaction from ethanol solution. To further improve their electrochemical properties, a ball milling process with carbon has been used to form composites. The fluorides were characterized by X-ray diffraction (XRD), thermal analysis, FTIR spectroscopy, galvanostatic charge/discharge and cyclic voltammetry measurements. The results showed that the as-prepared β-FeF{sub 3}·3H{sub 2}O/C exhibited better rate performance and cycling stability. It exhibited an initial discharge capacity of 199.6 mA h g{sup −1} at a current density of 20 mA g{sup −1} in a voltage range of 1.8–4.5 V and still reserved a discharge capacity of about 146.5 mA h g{sup −1} after 10 cycles. Only a capacity loss of 15 mA h g{sup −1} and 7 mA h g{sup −1} was observed when the current density was at 40 mA g{sup −1} and 80 mA g{sup −1}, respectively.

  2. Polymer gel electrolytes for lithium batteries

    NASA Astrophysics Data System (ADS)

    Baskakova, Yu V.; Yarmolenko, Ol'ga V.; Efimov, Oleg N.

    2012-04-01

    The data on the most promising polymer gel electrolytes for lithium batteries published in the past decade are surveyed and described systematically. Gel electrolytes with matrices of polyethylene oxide, poly(vinylidene fluoride) and its copolymer with hexafluoropropylene, poly(methyl methacrylate), polyacrylonitrile, poly(vinyl chloride) and polyacrylates are discussed. A special section is devoted to gel electrolytes with ionic liquids as the solvents. The bibliography includes 160 references.

  3. The effect of fluoride on the developing tooth.

    PubMed

    Robinson, C; Connell, S; Kirkham, J; Brookes, S J; Shore, R C; Smith, A M

    2004-01-01

    This review aims to outline the effects of fluoride on the biological processes involved in the formation of tooth tissues, particularly dental enamel. Attention has been focused on mechanisms which, if compromised, could give rise to dental fluorosis. The literature is extensive and often confusing but a much clearer picture is emerging based on recent more detailed knowledge of odontogenesis. Opacity, characteristic of fluorotic enamel, results from incomplete apatite crystal growth. How this occurs is suggested by other changes brought about by fluoride. Matrix proteins, associated with the mineral phase, normally degraded and removed to permit final crystal growth, are to some extent retained in fluorotic tissue. Fluoride and magnesium concentrations increase while carbonate is reduced. Crystal surface morphology at the nano-scale is altered and functional ameloblast morphology at the maturation stage also changes. Fluoride incorporation into enamel apatite produces more stable crystals. Local supersaturation levels with regard to the fluoridated mineral will also be elevated facilitating crystal growth. Such changes in crystal chemistry and morphology, involving stronger ionic and hydrogen bonds, also lead to greater binding of modulating matrix proteins and proteolytic enzymes. This results in reduced degradation and enhanced retention of protein components in mature tissue. This is most likely responsible for porous fluorotic tissue, since matrix protein removal is necessary for unimpaired crystal growth. To resolve the outstanding problems of the role of cell changes and the precise reasons for protein retention more detailed studies will be required of alterations to cell function, effect on specific protein species and the nano-chemistry of the apatite crystal surfaces.

  4. Mechanistic understanding of enamel mineralization under fluoride regime.

    PubMed

    Aoba, T; Taya, Y; Sato, A; Shimada, T; Mura-Galelli, M J

    1995-01-01

    In order to learn more about how the microenvironment for enamel mineralization is modified by fluoride at low concentrations (0 through 1 ppm) and how excess fluoride retards the degradation and removal of amelogenins, we studied precipitation reactions in an in vitro model utilizing a dialysis chamber. The results showed that, with the limited supply of Ca ions through the ultrafiltration membrane, the solution composition surrounding the seed crystals showed a proximity to the steady-state condition after 12-24 h equilibration. Major findings were that (a) fluoride overcame partially the inhibition of precipitation and growth reactions by enamel proteins and (b), with this accelerating effect of fluoride, the steady-state Ca concentrations in the media surrounding the seed crystals decreased substantially as a function of fluoride concentration. The overall results support the concept that the presence of fluoride in the mineralizing milieu can modify markedly the steady-state concentrations of mineral lattice ions, particularly decreasing free Ca2+ concentrations, which in turn may modulate protease activities in situ. PMID:7554946

  5. Efficient, green laser based on a blue-diode pumped rare-earth-doped fluoride crystal in an extremely short resonator

    NASA Astrophysics Data System (ADS)

    Strotkamp, Michael; Schwarz, Thomas; Jungbluth, Bernd; Faidel, Heinrich; Leers, Michael

    2010-02-01

    The green cw laser presented in this work is realized by means of a Pr:YLF crystal emitting at 523 nm that is pumped by a blue GaN laser diode in an extremely short resonator. With a 500 mW-diode a laser has been achieved with M2 = 1, a slope of 40 % and an output power of 140mW with an absorbed pump power of 410 mW which results in an electrooptical efficiency of 6.5 %. Despite the reduced overlap with a 1 W-diode the output power rises to 290 mW with an absorbed pump power of 850 mW and the M2 increases only slightly. Based on these results a compact laser package has been accomplished using a monolithic micro optics for the beam shaping of the diode light and joining all components with a low-shrinkage adhesive on a common base plate. In a first test of the alignment strategy a laser with an output power of 92 mW has been achieved by means of the 500 mW pump power.

  6. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients. PMID:25095960

  7. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients.

  8. Private Well Water and Fluoride

    MedlinePlus

    ... from my well has less than the recommended level of fluoride for preventing tooth decay? The recommended ... if the water from my well has fluoride levels that are higher than the recommended level for ...

  9. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    DOEpatents

    Barton, C.J.; Grimes, W.R.

    1960-01-01

    Molten-salt reactor fuel compositions consisting of mixtures of fluoride salts are reported. In its broadest form, the composition contains an alkali fluoride such as sodium fluoride, zirconium tetrafluoride, and a uranium fluoride, the latter being the tetrafluoride or trifluoride or a mixture of the two. An outstanding property of these fuel compositions is a high coeffieient of thermal expansion which provides a negative temperature coefficient of reactivity in reactors in which they are used.

  10. In situ TEM observation of lithium nanoparticle growth and morphological cycling.

    PubMed

    Ghatak, Jay; Guan, Wei; Möbus, Günter

    2012-03-01

    Lithium fluoride crystals were subjected to electron beam irradiation at 200 and 300 keV using transmission electron microscopy in order to study in situ fabrication of Li nanostructures. We observed that LiF crystals decompose in a unique way different to all other metal halides: Fluorine ablation and salt-to-metal conversion is non-local and due to a rapid lateral diffusion of Li, the life cycle from nucleation to annihilation of fresh Li nano-crystals can be observed at a distance from the Li-source, the irradiated salt. Growth, shape transition and annihilation of Li nanostructures follow at slow enough speed for live video recording with resolution of 25 frames per second. The equilibrium shapes of pure Li nano-crystals range from cubic to rod-shaped and ball-shaped and up to 300 nm size. By varying the e-beam flux of irradiation, transitions from cube to spherical shape can be induced cyclically.

  11. Lithium toxicity

    MedlinePlus

    ... dialysis (machine) Medicines to treat symptoms Whole bowel irrigation with a special solution taken by mouth or through a tube through the nose into the stomach (to flush sustained-release lithium quickly through the stomach and intestines)

  12. Synthesis of SnO2versus Sn crystals within N-doped porous carbon nanofibers via electrospinning towards high-performance lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Hongkang; Lu, Xuan; Li, Longchao; Li, Beibei; Cao, Daxian; Wu, Qizhen; Li, Zhihui; Yang, Guang; Guo, Baolin; Niu, Chunming

    2016-03-01

    The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent characteristics. Herein, particulate SnO2 or Sn crystals coupled with porous N-doped carbon nanofibers (denoted as SnO2/PCNFs and Sn/PCNFs, respectively) are fabricated via the electrospinning method. The electrochemical behaviors of both SnO2/PCNFs and Sn/PCNFs are systematically investigated as anodes for LIBs. When coupled with porous carbon nanofibers, both SnO2 nanoparticles and Sn micro/nanoparticles display superior cycling and rate performances. SnO2/PCNFs and Sn/PCNFs deliver discharge capacities of 998 and 710 mA h g-1 after 140 cycles (at 100, 200, 500 and 1000 mA g-1 each for 10 cycles and then 100 cycles at 100 mA g-1), respectively. However, the Sn/PCNF electrodes show better cycling stability at higher current densities, delivering higher discharge capacities of 700 and 550 mA h g-1 than that of SnO2/PCNFs (685 and 424 mA h g-1) after 160 cycles at 200 and 500 mA g-1, respectively. The different superior electrochemical performance is attributed to the introduction of porous N-doped carbon nanofibers and their self-constructed networks, which, on the one hand, greatly decrease the charge-transfer resistance due to the high conductivity of N-doped carbon fibers; on the other hand, the porous carbon nanofibers with numerous voids and flexible one-dimensional (1D) structures efficiently alleviate the volume changes of SnO2 and Sn during the Li-Sn alloying-dealloying processes. Moreover, the discussion of the electrochemical behaviors of SnO2vs. Sn would provide new insights into the design of tin-based anode materials for practical applications, and the current strategy demonstrates great potential in the rational design of metallic tin-based anode materials.The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent

  13. Second order nonlinear optical properties of In-doped lithium niobate

    NASA Astrophysics Data System (ADS)

    Xue, D.; Betzler, K.; Hesse, H.

    2001-01-01

    Second order nonlinear optical properties of In-doped lithium niobate crystals have been quantitatively studied from the chemical bond viewpoint. The results show that the second order nonlinear optical response of In-doped lithium niobate crystals at 1079 nm decreases remarkably with increasing In concentration in the crystal. This approximately linear composition-property correlation in In-doped lithium niobate crystals is quantitatively expressed in the current work. Furthermore, the different influences of Mg, Zn, and In dopants, respectively, on the nonlinear susceptibility of lithium niobate single crystals are also compared in the present work.

  14. Barium solubility in colquiriite fluorides

    SciTech Connect

    Yaobo Yin; Keszler, D.A. )

    1993-12-01

    Several crystals in the family of Colquiriite fluorides LiAEMF[sub 6] (AE = Ca, Sr; M = Al, Ga, Cr) have been reported to function as efficient, broadly tunable laser materials when doped with the ion Cr[sup 3+]. The optical characteristics of the Cr[sup 3+] ion are considerably affected by the specific AE atom in the crystal. In this paper the systems LiSr[sub 1[minus]x]Ba[sub x]MF[sub 6](M = Al, Ga) have been studied by powder and single-crystal X-ray diffraction methods. Solubility limits of x = 0.06 for the Al compound and x = 0.20 for the Ga compound have been established. The structures of LiSr[sub 0.94(1)]Ba[sub 0.06]AlF[sub 6] and LiSr[sub 0.80(1)]Ba[sub 0.20]GaF[sub 6] corresponding to these limits are isotypic to the mineral Colquiriite. Each crystallizes in space group P[bar 3]1c: LiSr[sub 0.94]Ba[sub 0.06]AlF[sub 6]: a = 5.096(1) [angstrom], c = 10.269(2) [angstrom], R = 0.034, R[sub w] = 0.041; and LiSr[sub 0.80]Ba[sub 0.20]GaF[sub 6]: a = 5.173(1) [angstrom], c = 10.415(1) [angstrom], R = 0.028, R[sub w] = 0.033. The trigonal F planes about the Al and Ga atoms are rotated, one relative to the other, by 68.0 and 69.0[degrees], respectively.

  15. X-ray diffraction studies of phase transformations in heavy-metal fluoride glasses

    NASA Technical Reports Server (NTRS)

    Bansal, N. P.; Doremus, R. H.

    1985-01-01

    Powder X-ray diffraction and differential scanning calorimetry studies of the crystallization properties of five ZrF4-based glass compositions have indicated that the crystalline phase in Zr-Ba-La-Pb fluoride glass is beta-BaZrF6; no such identification of crystal phases was obtainable, however, for the other glasses. Reversible polymorphic phase transformations occur in Zr-Ba-La-Li and Zr-Ba-La-Na fluoride glasses, upon heating to higher temperatures.

  16. Direct measurements of stratospheric fluoride

    NASA Technical Reports Server (NTRS)

    Mroz, E. J.; Lazrus, A. L.; Bonelli, J. E.

    1977-01-01

    Stratospheric fluoride mass mixing ratios were measured by passing stratospheric air through filters half of which is impregnated in a base. Measurements of stratospheric fluoride were obtained at altitudes from 15 to 40 km at latitude 30-33 N and longitude 95-105 W at different months of the year. The significant amount of fluoride collected on the base-impregnated portion of the filters suggests that fluoride is present in the stratosphere as an acid gas. The mixing ratios decrease markedly at altitudes less than 20-25 km, suggesting the troposphere as the major sink for stratospheric fluoride.

  17. Stabilization of Th{sup 3+} ions into mixed-valence thorium fluoride

    SciTech Connect

    Dubois, Marc; Dieudonne, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-15

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li{sub 2+x}Th{sub 12}F{sub 50} (0crystal X-ray diffraction and high resolution synchrotron powder diffraction. In these phases, the Li{sup +} ions can be divided into two groups and are located either in locked positions or in open channels of the three dimensional framework. The amount of Li{sup +} ions in open channels can be variable, so that the afore mentioned single phase may be considered as an insertion compound. The Li{sup +} insertion is accompanied by the simultaneous reduction of a part of the Th{sup 4+} ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li{sup +} ions into the open channels of the host matrix has been carried out at 60 {sup o}C, using an alkylcarbonate PC-LiClO{sub 4} 1 M electrolyte. The Li{sup +} and Th{sup 3+} contents, both in the starting composition and the Li{sup +} inserted ones, were investigated by high resolution solid state {sup 7}Li NMR and EPR, respectively. -- Graphical abstract: Electrochemical insertion of Li{sup +} ions into mixed-valence III/IV thorium fluoride and EPR spectra for the raw and inserted compounds. Display Omitted

  18. Fluorine (soluble fluoride)

    Integrated Risk Information System (IRIS)

    Fluorine ( soluble fluoride ) ; CASRN 7782 - 41 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for No

  19. Other Fluoride Products

    MedlinePlus

    ... in preventing tooth decay in people of all ages. Use the information listed below to compare the other fluoride products ... even among children younger than 6 years of age. Proper application technique ... cleared for marketing by the Food and Drug Administration (FDA) as ...

  20. Ferrimyoglobin-Fluoride.

    ERIC Educational Resources Information Center

    Russo, Steven O.; Hanania, George I. H.

    1990-01-01

    Described is an experiment which is designed to investigate the reaction of the protein ferrimyoglobin with fluoride. The activity uses readily available apparatus and the technique of optical absorbance for measurement of concentrations. Experimental design, procedures, and treatment of the equilibrium data are detailed. (CW)

  1. Advantages of liquid fluoride thorium reactor in comparison with light water reactor

    SciTech Connect

    Bahri, Che Nor Aniza Che Zainul Majid, Amran Ab.; Al-Areqi, Wadeeah M.

    2015-04-29

    Liquid Fluoride Thorium Reactor (LFTR) is an innovative design for the thermal breeder reactor that has important potential benefits over the traditional reactor design. LFTR is fluoride based liquid fuel, that use the thorium dissolved in salt mixture of lithium fluoride and beryllium fluoride. Therefore, LFTR technology is fundamentally different from the solid fuel technology currently in use. Although the traditional nuclear reactor technology has been proven, it has perceptual problems with safety and nuclear waste products. The aim of this paper is to discuss the potential advantages of LFTR in three aspects such as safety, fuel efficiency and nuclear waste as an alternative energy generator in the future. Comparisons between LFTR and Light Water Reactor (LWR), on general principles of fuel cycle, resource availability, radiotoxicity and nuclear weapon proliferation shall be elaborated.

  2. Advantages of liquid fluoride thorium reactor in comparison with light water reactor

    NASA Astrophysics Data System (ADS)

    Bahri, Che Nor Aniza Che Zainul; Majid, Amran Ab.; Al-Areqi, Wadeeah M.

    2015-04-01

    Liquid Fluoride Thorium Reactor (LFTR) is an innovative design for the thermal breeder reactor that has important potential benefits over the traditional reactor design. LFTR is fluoride based liquid fuel, that use the thorium dissolved in salt mixture of lithium fluoride and beryllium fluoride. Therefore, LFTR technology is fundamentally different from the solid fuel technology currently in use. Although the traditional nuclear reactor technology has been proven, it has perceptual problems with safety and nuclear waste products. The aim of this paper is to discuss the potential advantages of LFTR in three aspects such as safety, fuel efficiency and nuclear waste as an alternative energy generator in the future. Comparisons between LFTR and Light Water Reactor (LWR), on general principles of fuel cycle, resource availability, radiotoxicity and nuclear weapon proliferation shall be elaborated.

  3. The value of self-applied fluorides at home.

    PubMed

    Holloway, P J; Levine, R S

    1981-09-01

    Dental research workers from several scientific disciplines have combined over the years to give much greater insight into the basic mechanisms whereby fluoride protects the teeth against dental decay. These basic investigations have enabled clinical research workers to test new fluoride delivery systems rationally rather than empirically, and it now seems that two entirely different modes need to be combined to form maximum protection. First, fluoride ions need to be introduced at the correct level into the forming enamel crystals during tooth development; secondly, fluoride ions need to be present at optimal concentrations at the plague-enamel interface during active carious attack. Both these situations require low levels of fluoride concentration to be delivered to the subject at very regular intervals. Water fluoridation is the best method of achieving this situation, but in the absence of this important public health measure, dental scientists have developed a battery of other vehicles which, when used on a daily basis at home, will have a considerable impact on caries activity. While further work continues to improve the effectiveness of these techniques, enough has been achieved already to encourage their use by the general public. What are required now are the necessary skills in health politics and behavioral science to gain public acceptance and application of these endeavours.

  4. Health Effects Associated with Water Fluoridation.

    ERIC Educational Resources Information Center

    Richmond, Virginia L.

    1979-01-01

    Discussion is presented concerning fluoridation of water supplies. Correlation between fluoride in drinking water and improved dental health is reviewed. Relationship is expressed between fluoridation and reduced tooth decay. Use of fluoride in treating skeletal disorders is discussed. Author advocates fluoridating water supplies. (SA)

  5. Crystal growth of a series of lithium garnets Ln3Li 5Ta 2O 12 ( Ln=La, Pr, Nd): Structural properties, Alexandrite effect and unusual ionic conductivity

    NASA Astrophysics Data System (ADS)

    Roof, Irina P.; Smith, Mark D.; Cussen, Edmund J.; zur Loye, Hans-Conrad

    2009-02-01

    We report the single crystal structures of a series of lanthanide containing tantalates, Ln3Li 5Ta 2O 12 ( Ln=La, Pr, Nd) that were obtained out of a reactive lithium hydroxide flux. The structures of Ln3Li 5Ta 2O 12 were determined by single crystal X-ray diffraction, where the Li + positions and Li + site occupancies were fixed based on previously reported neutron diffraction data for isostructural compounds. All three oxides crystallize in the cubic space group Ia3¯d (No. 230) with lattice parameters a=12.7735(1), 12.6527(1), and 12.5967(1) Å for La 3Li 5Ta 2O 12, Pr 3Li 5Ta 2O 12, and Nd 3Li 5Ta 2O 12, respectively. A UV-Vis diffuse reflectance spectrum of Nd 3Li 5Ta 2O 12 was collected to explain its unusual Alexandrite-like optical behavior. To evaluate the transport properties of Nd 3Li 5Ta 2O 12, the impedance data were collected in air in the temperature range 300⩽ T(°C)⩽500.

  6. Biomarkers of fluoride in children exposed to different sources of systemic fluoride.

    PubMed

    Buzalaf, M A R; Rodrigues, M H C; Pessan, J P; Leite, A L; Arana, A; Villena, R S; Forte, F D S; Sampaio, F C

    2011-02-01

    There has been no comparison between fluoride concentrations in urine and nails of children exposed to different sources of systemic fluoride. The aim of this study was to compare the relationship between fluoride intake with urinary fluoride excretion and fluoride concentrations in fingernails and toenails of children receiving fluoride from artificially fluoridated water (0.6-0.8 mg F/L, n = 25), naturally fluoridated water (0.6-0.9 mg F/L, n = 21), fluoridated salt (180-200 mg F/Kg, n = 26), and fluoridated milk (0.25 mg F, n = 25). A control population was included (no systemic fluoride, n = 24). Fluoride intake from diet and dentifrice, urinary fluoride excretion, and fluoride concentrations in fingernails/toenails were evaluated. Fluoride was analyzed with an ion-selective electrode. Urinary fluoride excretion in the control community was significantly lower when compared with that in the fluoridated cities, except for the naturally fluoridated community. However, the same pattern was not as evident for nails. Both urinary fluoride output and fluoride concentrations in fingernails/toenails were significantly correlated to total fluoride intake. However, the correlation coefficients for fluoride intake and urinary fluoride output were lower (r = 0.28, p < 0.01) than those observed for fingernails/toenails (r = 0.36, p < 0.001), suggesting that nails might be slightly better indicators of fluoride intake at the individual level.

  7. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    NASA Technical Reports Server (NTRS)

    West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

    2007-01-01

    We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

  8. Stabilization of Th 3+ ions into mixed-valence thorium fluoride

    NASA Astrophysics Data System (ADS)

    Dubois, Marc; Dieudonné, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-01

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li 2+ xTh 12F 50 (0< x<1.8). This phase is closely related to the Li 5.5Ce 12F 50 one, the structure of which has been determined from the combined single-crystal X-ray diffraction and high resolution synchrotron powder diffraction. In these phases, the Li + ions can be divided into two groups and are located either in locked positions or in open channels of the three dimensional framework. The amount of Li + ions in open channels can be variable, so that the afore mentioned single phase may be considered as an insertion compound. The Li + insertion is accompanied by the simultaneous reduction of a part of the Th 4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li + ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO 4 1 M electrolyte. The Li + and Th 3+ contents, both in the starting composition and the Li + inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively.

  9. Transition Metal-Substituted Lithium Pnictogenide phases. Synthesis and Crystal Structure Determinations of Novel Phases in the Li-M-X Systems (M=V, Nb, Ta; X=P, As)

    SciTech Connect

    Monconduit, Laure; Tillard-Charbonnel, Monique; Belin, Claude

    2001-01-01

    Li-M-X systems have been investigated and crystal structures of several phases determined. Li{sub 7}NbP{sub 4} crystallizes in the antifluorite-type structure (cubic, Fm{ovr 3}m, a=5.996(1) {angstrom}, Z=1, R (F)=3.02%). LiNbAs{sub 2} and Li{sub 4.54}V{sub 1.22}As{sub 4} display the blende-type structure, cubic F{ovr 4}3m space group (LiNbAs{sub 2}: a= 6.309(1) {angstrom}, Z=2, R(F)=2.12%; Li{sub 4.54}V{sub 1.22}As{sub 4}: a=6.167(1) {angstrom}, Z=1, R(F)=1.49%). In all compounds, the transition metal statistically occupies some of the tetrahedral sites with lithium. For Li{sub 4.54}V{sub 1.22}As{sub 4}, one of the octahedral sites of the fcc lattice is partially filled with lithium. This feature is also observed for the homologue compounds Li{sub x}(Li{sub 3.20}Nb{sub 0.80})As{sub 4} and Li{sub x}(Li{sub 3.64}Ta{sub 0.36})As{sub 4}, 0 < x {le} 4 (F3m, Z=1, a=6.190(3) and 6.184(3) {angstrom}, R (F)=1.76 and 3.42%, respectively).

  10. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is contacted with an acid under certain prescribed conditions to produce a liquid product and a particulate solid product. The particulate solid product is separated from the liquid and treated at least two more times with acid to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm. In accordance with a particularly preferred embodiment of the invention a catalyst and an oxidizing agent are used during the acid treatment and preferably the acid is sulfuric acid having a strength of about 1.0 Normal.

  11. Plasma and Brain Pharmacokinetics of Previously Unexplored Lithium Salts

    PubMed Central

    Smith, Adam J.; Kim, Seol-Hee; Tan, Jun; Sneed, Kevin B.; Sanberg, Paul R.; Borlongan, Cesar V.; Shytle, R. Douglas

    2014-01-01

    Despite its narrow therapeutic window, lithium is still regarded as the gold standard comparator and benchmark treatment for mania. Recent attempts to find new drugs with similar therapeutic activities have yielded new chemical entities. However, these potential new drugs have yet to match the many bioactivities attributable to lithium's efficacy for the treatment of neuropsychiatric diseases. Consequently, an intense effort for re-engineering lithium therapeutics using crystal engineering is currently underway. We sought to improve the likelihood of success of these endeavors by evaluating the pharmacokinetics of previously unexplored lithium salts with organic anions (lithium salicylate and lithium lactate). We report that these lithium salts exhibit profoundly different pharmacokinetics compared to the more common FDA approved salt, lithium carbonate, in rats. Remarkably, lithium salicylate produced elevated plasma and brain levels of lithium beyond 48 hours post-dose without the sharp peak that contributes to the toxicity problems of current lithium therapeutics. These findings could be important for the development of the next generation of lithium therapeutics. PMID:25045517

  12. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and “turn on” fluorescent sensors for fluoride anion sensing employing hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Ashok Kumar, S. L.; Saravana Kumar, M.; Sreeja, P. B.; Sreekanth, A.

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques.

  13. Crystal growth of a series of lithium garnets Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} (Ln=La, Pr, Nd): Structural properties, Alexandrite effect and unusual ionic conductivity

    SciTech Connect

    Roof, Irina P.; Smith, Mark D.; Cussen, Edmund J.; Loye, Hans-Conrad zur

    2009-02-15

    We report the single crystal structures of a series of lanthanide containing tantalates, Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} (Ln=La, Pr, Nd) that were obtained out of a reactive lithium hydroxide flux. The structures of Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} were determined by single crystal X-ray diffraction, where the Li{sup +} positions and Li{sup +} site occupancies were fixed based on previously reported neutron diffraction data for isostructural compounds. All three oxides crystallize in the cubic space group Ia3-bard (No. 230) with lattice parameters a=12.7735(1), 12.6527(1), and 12.5967(1) A for La{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, Pr{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, and Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, respectively. A UV-Vis diffuse reflectance spectrum of Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} was collected to explain its unusual Alexandrite-like optical behavior. To evaluate the transport properties of Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, the impedance data were collected in air in the temperature range 300{<=}T(deg. C){<=}500. - Graphical abstract: Crystal structure of garnets Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} (Ln=La, Pr, Nd). TaO{sub 6} polyhedra are shown in yellow and Ln{sup 3+} are shown as light blue spheres. Octahedrally and tetrahedrally coordinated Li{sup +} ions are shown in green and brown, respectively. Oxygen atoms are omitted for clarity.

  14. Radiation effects on Yb:YLF crystals used in cryogenic optical refrigerators

    NASA Astrophysics Data System (ADS)

    Martin, K. W.; Melgaard, S.; Cowan, V. M.; Hubbs, J.; Fraser, T.; Sheik-Bahae, M.

    2015-09-01

    Optical cooling of solids is a promising and innovative method to provide cryogenic cooling to infrared sensors. Currently insulator crystals, specifically ytterbium-doped yttrium- lithium-fluoride (Yb:YLF), have shown the most promise for cooling to low temperatures. This method has demonstrated cooling below the National Institute of Standards and Technology (NIST) cryogenic temperature definition of less than 123 K. Optical refrigeration utilizes a phenomenon called anti-Stokes fluorescence to generate cooling power. Incident laser light is absorbed by the cooling crystal and photons are spontaneously emitted at a higher, and thus more energetic, frequency. The difference in frequency is proportional to the cooling power of the crystal. Anti-Stokes cooling is highly dependent on doping percentages and YLF crystal purity and structure. Space based infrared sensors and their coolers are operated in a radiation environment where protons, gamma, rays, heavy ions, and other radiation species are common and of varying severities depending on operational orbit. To ensure that radiative effects on cooling crystal performance are minimal, we irradiated two samples with 63 MeV protons to a total of ionized dose of 100 Krad (Si) and 1 Mrad (Si), and compared cooling crystal efficiency parameters before and after dosing.

  15. Lithium in 2012

    USGS Publications Warehouse

    Jaskula, B.W.

    2013-01-01

    In 2012, estimated world lithium consumption was about 28 kt (31,000 st) of lithium contained in minerals and compounds, an 8 percent increase from that of 2011. Estimated U.S. consumption was about 2 kt (2,200 st) of contained lithium, the same as that of 2011. The United States was thought to rank fourth in consumption of lithium and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. One company, Rockwood Lithium Inc., produced lithium compounds from domestic brine resources near Silver Peak, NV.

  16. Fluoride Content in Alcoholic Drinks.

    PubMed

    Goschorska, Marta; Gutowska, Izabela; Baranowska-Bosiacka, Irena; Rać, Monika Ewa; Chlubek, Dariusz

    2016-06-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual samples were measured by potentiometric method with a fluoride ion-selective electrode. The highest fluoride levels were determined in the lowest percentage drinks (less than 10 % v/v ethanol), with the lowest fluoride levels observed in the highest percentage drinks (above 40 % v/v ethanol). In terms of types of alcoholic drinks, the highest fluoride levels were determined in beers and wines, while the lowest levels were observed in vodkas. These data confirm the fact that alcoholic beverages need to be considered as a significant source of fluoride delivered into the body. PMID:26475300

  17. WET FLUORIDE SEPARATION METHOD

    DOEpatents

    Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

    1958-11-25

    The separation of U/sup 233/ from thorium, protactinium, and fission products present in neutron-irradiated thorium is accomplished by dissolving the irradiated materials in aqueous nitric acid, adding either a soluble fluoride, iodate, phosphate, or oxalate to precipltate the thorium, separating the precipltate from the solution, and then precipitating uranlum and protactinium by alkalizing the solution. The uranium and protactinium precipitate is removcd from the solution and dissolved in nitric acid. The uranyl nitrate may then be extracted from the acid solution by means of ether, and the protactinium recovered from the aqueous phase.

  18. A consideration of the morphology of electrochemically deposited lithium in an organic electrolyte

    NASA Astrophysics Data System (ADS)

    Yamaki, Jun-ichi; Tobishima, Shin-ichi; Hayashi, Katsuya; Keiichi Saito; Nemoto, Yasue; Arakawa, Masayasu

    Lithium rechargeable cells with lithium metal anodes are widely considered to have the highest energy density among comparable cells. However the life cycle and thermal stability of these cells must be improved. The poor performance of lithium metal cells is mainly explained by lithium dendrite growth. With a view to overcoming this problem, we considered the lithium deposition mechanism. We have been carrying out various experiments on the lithium deposition behavior. In this paper we used these results to propose the current and most likely lithium deposition mechanism. We suggest that lithium dendrites may be called whiskers because their shape satisfies the definition of whiskers as `fibrous crystals'. Their tip morphology remains unchanged during their growth, which means they grow from the base in the same way as whiskers of tin from thin films under stress. Lithium deposited under a protective film will experience stress because the deposition is non-uniform. The protective film will break in order to release this stress thus, lithium whiskers may then grow in the form of extrusions. To support our assumption, we calculated the possible morphology of the lithium with the boundary condition that pressure induced by the surface tension is the same throughout the lithium surface. The calculation indicated three types of shape depending on the value of the surface tension and internal pressure. If lithium deformation is limited by the creep strength of bulk lithium and the lithium whiskers, the whisker growth is described by the calculated shape.

  19. Determination of Stability Constants of Hydrogen and Aluminum Fluorides with a Fluoride-Selective Electrode

    SciTech Connect

    Baumann, E.W.

    2003-01-06

    The ability to directly determine free fluoride ion concentration (or mean activity) simplifies gathering and interpretation of experimental data for studies of metal complexes. In this work, the new lanthanum fluoride electrode was used to measure free fluoride ion in an investigation of the hydrogen-fluoride and aluminum-fluoride systems in NH4NO3.

  20. Urinary Fluoride Concentration in Children with Disabilities Following Long-Term Fluoride Tablet Ingestion

    ERIC Educational Resources Information Center

    Liu, Hsiu-Yueh; Chen, Jung-Ren; Hung, Hsin-Chia; Hsiao, Szu-Yu; Huang, Shun-Te; Chen, Hong-Sen

    2011-01-01

    Urine is the most commonly utilized biomarker for fluoride excretion in public health and epidemiological studies. Approximately 30-50% of fluoride is excreted from urine in children. Urinary fluoride excretion reflects the total fluoride intake from multiple sources. After administering fluoride tablets to children with disabilities, urinary…

  1. Mechanisms for the Crystallization of ZBLAN

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Tucker, Dennis S.; Kaukler, William; Antar, Basil

    2003-01-01

    The objective of this ground based study is to test the hypothesis that shear thinning (the non-Newtonian response of viscosity to shear rate) is a viable mechanism to explain the observation of enhanced glass formation in numerous low-g experiments. In 1-g, fluid motion results from buoyancy forces and surface tension driven convection. This fluid flow will introduce shear in undercooled liquids in 1-g. In low-g it is known that fluid flows are greatly reduced so that the shear rate in fluids can be extremely low. It is believed that some fluids may have weak structure in the absence of flow. Very small shear rates could cause this structure to collapse in response to shear resulting in a lowering of the viscosity of the fluid. The hypothesis of this research is that: Shear thinning in undercooled liquids decreases the viscosity, increasing the rate of nucleation and crystallization of glass forming melts. Shear in the melt can be reduced in low-g, thus enhancing undercooling and glass formation. The viscosity of a model glass (lithium di-silicate, L2S) often used for crystallization studies has been measured at very low shear rates using a dynamic mechanical thermal analyzer. Our results are consistent with increasing viscosity with a lowering of shear rates. The viscosity of L2S may vary as much as an order of magnitude depending on the shear rate in the temperature region of maximum nucleation and crystal growth. Classical equations for nucleation and crystal growth rates, are inversely related to the viscosity and viscosity to the third power respectively. An order of magnitude variation in viscosity (with shear) at a given temperature would have dramatic effects on glass crystallization Crystallization studies with the heavy metal fluoride glass ZBLAN (ZrF2-BaF2-LaF3-AlF3-NaF) to examine the effect of shear on crystallization are being initiated. Samples are to be melted and quenched under quiescent conditions at different shear rates to determine the effect

  2. Long cycle life lithium ion battery with lithium nickel cobalt manganese oxide (NCM) cathode

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Xiong, L.; He, C.

    2014-09-01

    Lithium ion batteries with lithium nickel cobalt manganese oxide (NCM) cathode were characterized by extensive cycling (>2000 cycles), discharge rate test, hybrid pulse power characterization test (HPPC), and electrochemical impedance spectroscopy (EIS). The crystal structure, morphology and particle size of cathode materials were characterized by X-ray diffraction and scanning electron microscopy (SEM). It was demonstrated that the rate performance and cycle life of battery are closely related to the cathode material composition and electrode design. With proper selection of cathode composition and electrode design, the lithium ion battery cell achieved close to 3500 cycles with 85% capacity retention at 1C current.

  3. Fluorination Induced the Surface Segregation of High Voltage Spinel on Lithium-Rich Layered Cathodes for Enhanced Rate Capability in Lithium Ion Batteries.

    PubMed

    Jin, Yi-Chun; Duh, Jenq-Gong

    2016-02-17

    This study is aimed to explore the effect of fluoride doping and the associated structural transformation on lithium-rich layered cathode materials. The polymeric fluoride source is first adopted for synthesizing lithium intercalated oxide through a newly developed organic precipitation process. A heterostructured spinel/layered composite cathode material is obtained after appreciable fluorination and a superior rate capability is successfully achieved. The fluoride dopant amount and the surface spinel phase are evidenced and systematically examined by various structural spectroscopy and electrochemical analysis. It appears the reversible Ni(2+/4+) redox couple at high voltage regime around 4.8 V because of the formation of spinel LiNi1/2Mn3/2O4 phase. The mechanism of "layer to spinel" phase transformation is discussed in detail.

  4. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  5. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  6. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  7. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  8. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  9. Vapor-liquid equilibria for the systems difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride

    SciTech Connect

    Kang, Y.W.

    1998-01-01

    Isothermal vapor-liquid equilibria for difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. The binary system difluoromethane + hydrogen fluoride forms a homogeneous liquid phase, and the others form minimum boiling heterogeneous azeotropes at the experimental conditions.

  10. Lithium-associated hyperthyroidism.

    PubMed

    Siyam, Fadi F; Deshmukh, Sanaa; Garcia-Touza, Mariana

    2013-08-01

    Goiters and hypothyroidism are well-known patient complications of the use of lithium for treatment of bipolar disease. However, the occurrence of lithium-induced hyperthyroidism is a more rare event. Many times, the condition can be confused with a flare of mania. Monitoring through serial biochemical measurement of thyroid function is critical in patients taking lithium. Hyperthyroidism induced by lithium is a condition that generally can be controlled medically without the patient having to discontinue lithium therapy, although in some circumstances, discontinuation of lithium therapy may be indicated. We report on a patient case of lithium-associated hyperthyroidism that resolved after discontinuation of the medication. PMID:23948626

  11. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries.

    PubMed

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-01-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4-δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4-δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn(3+) from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF. PMID:27553901

  12. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-08-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4‑δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4‑δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn3+ from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF.

  13. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries.

    PubMed

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-01-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4-δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4-δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn(3+) from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF.

  14. Protactinium distribution in a fluoride melt in the presence of solid oxide phases

    SciTech Connect

    Alekseev, V.A.; Ziv, V.S.; Morozova, Z.E.

    1989-01-01

    Measurements have been made on protactinium distributions between molten lithium and sodium fluorides and solid lanthanum or zirconium oxides as affected by time, amount of solid, and amount of gas (air of argon) at 1023 K. Protactinium can be extracted quantitatively from LiF-NaF melts by the two oxides. It is found that all the regularities previously reported for actinoid distributions in halide liquids in the presence of oxides apply to protactinium.

  15. Equilibrium distribution of samarium and europium between fluoride salt melts and liquid bismuth

    NASA Astrophysics Data System (ADS)

    Zagnit'ko, A. V.; Ignat'ev, V. V.

    2016-01-01

    The extraction of samarium and europium from a melt of a molar composition 73LiF-27BeF2 into liquid bismuth with additions of lithium as a reducing agent at a temperature of 600-610°C was studied. The equilibrium distribution coefficients of samarium and europium were measured. In the metal fluoride salt melt under study, the valence of samarium and europium was shown to be equal to two.

  16. Defects and Luminescence in Lithium FLUORIDE:MAGNESIUM, Titanium

    NASA Astrophysics Data System (ADS)

    He, Shulin Sam

    This research investigated the characteristics of the defect centers produced by ionizing radiation in LiF:Mg,Ti and the mechanism of the luminescence associated with the defect centers. Experimental methods used in this work include the measurement of the optical absorption of the defect centers (produced by gamma ray irradiation) under thermal annealing treatment and optical bleaching treatment, the photoluminescence (after irradiation with gamma rays and/or neutrons) and the thermoluminescence (after irradiation with gamma rays and/or beta particles) related to the defect centers. It has been concluded that both Mg^{+2} ions and Ti^{+4} ions act as electron traps in LiF. Upon ionizing irradiation, a Mg ^{+2} ion can trap two electrons to form a Mg^{0} center absorbing at 3.25 eV in LiF and one electron to form a Mg^{+} center which absorbs at 3.5 eV, and a Mg^{+} center in a vacancy complex environment absorbs at 4.0 eV, in contrast to the Z center model and the Mg ^{+2}{rm V}_{ rm c}^{-} pair/trimer model. The absorption band near 5.5 eV in LiF:Mg,Ti produced by ionizing radiation at room temperature is attributed to Ti^{+3} ions (formed by Ti^{+4} ion's trapping of one electron) related charge transfer absorption. It could also be a result of the optical absorption of Z _3 centers and/or Mg^{+2 }{rm V}_{rm c} ^{-} dimers, trimers produced by thermal annealing and optical bleaching following irradiation. The mechanism of the luminescence spectra associated with these defect centers upon either optical excitation or thermal stimulation is concluded to be due to an electron-hole recombination process with the perturbation of vacancies and/or impurities. During the electron-hole recombination process, electrons originate from all electron traps (F center and its aggregates, Mg^{+2} ion and Ti^{+4} ion related defect centers) while hole centers are only V_3 centers if irradiated at room temperature, and include both V_{rm K} centers and V_3 center if irradiated at liquid nitrogen temperature.

  17. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  18. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Delcul, G. D.; Dai, S.; Metcalf, D. H.

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  19. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  20. Molten fluoride fuel salt chemistry

    SciTech Connect

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1994-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  1. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    SciTech Connect

    Bartlett, Neil; Whalen, J. Marc; Chacon, Lisa

    2000-12-12

    A method for fluorinating a carbon compound or cationic carbon compound utilizes a fluorination agent selected from thermodynamically unstable nickel fluorides and salts thereof in liquid anhydrous hydrogen fluoride. The desired carbon compound or cationic organic compound to undergo fluorination is selected and reacted with the fluorination agent by contacting the selected organic or cationic organic compound and the chosen fluorination agent in a reaction vessel for a desired reaction time period at room temperature or less.

  2. Complete sets of elastic constants and photoelastic coefficients of pure and MgO-doped lithium niobate crystals at room temperature

    SciTech Connect

    Andrushchak, A. S.; Laba, H. P.; Yurkevych, O. V.; Mytsyk, B. G.; Solskii, I. M.; Kityk, A. V.; Sahraoui, B.

    2009-10-01

    This paper presents the results of ultrasonic measurements of LiNbO{sub 3} and LiNbO{sub 3}:MgO crystals. The tensors of piezoelectric coefficients, elastic stiffness constants, and elastic compliances are determined for both crystals at room temperature. Combining these data with the results of piezo-optical measurements, a complete set of photoelastic tensor coefficients is also calculated. Doping of LiNbO{sub 3} crystals by MgO does not lead to a considerable modification of their elastic and photoelastic properties. However, LiNbO{sub 3}:MgO is characterized by a considerably higher resistance with respect to powerful light radiation, making it promising for future application in acousto-optic devices that deal with superpowerful laser radiation. Presented here are the complete tensor sets of elastic constants and photoelastic coefficients of LiNbO{sub 3} and LiNbO{sub 3}:MgO crystals that may be used for a geometry optimization of acousto-optical interaction providing the best diffraction efficiency of acousto-optical cells made of these materials.

  3. Do Fluoride Ions Protect Teeth?

    ERIC Educational Resources Information Center

    Parkin, Christopher

    1998-01-01

    Begins with the procedure and results from an investigation on the effect of fluoride on the reaction between eggshell (substitute teeth) and dilute ethanoic acid. Describes an elegantly modified and improvised apparatus. (DDR)

  4. A new approach to prepare nanoscopic rare earth metal fluorides: the fluorolytic sol-gel synthesis of ytterbium fluoride.

    PubMed

    Schmidt, L; Dimitrov, A; Kemnitz, E

    2014-06-25

    A new approach for the preparation of approx. 5 nm sized ytterbium fluoride nanoparticles based on the fluorolytic sol-gel route is reported. DLS, TEM, IR and XRD were used to characterize the particles as well as the aging behavior of the sols. Furthermore, a new Yb(III) complex was isolated from the precursor solution and characterized by X-ray single crystal structure determination.

  5. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries

    PubMed Central

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-01-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4−δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4−δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn3+ from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF. PMID:27553901

  6. Intergranular fracture of lithium fluoride-22 percent calcium fluoride hypereutectic salt at 800 K

    NASA Technical Reports Server (NTRS)

    Raj, Subramanium V.; Whittenberger, J. Daniel

    1990-01-01

    Substantial strain-hardening was noted during the initial stages of deformation in constant-velocity compression tests conducted on as-cast samples of the LiF-22 mol pct CaF2 hypereutectic salt at 800 K. The deformed specimens exhibited extensive grain-boundary cracking and cavitation, suggesting that such cracking, in conjunction with interfacial sliding, is important for cavity nucleation at grain boundaries and at the LiF-CaF2 interfaces. Cavity growth and interlinkage occur through the preferential failure of the weaker LiF phase.

  7. Molten salt lithium cells

    DOEpatents

    Raistrick, I.D.; Poris, J.; Huggins, R.A.

    1980-07-18

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400 to 500/sup 0/C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell which may be operated at temperatures between about 100 to 170/sup 0/C. The cell is comprised of an electrolyte, which preferably includes lithium nitrate, and a lithium or lithium alloy electrode.

  8. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1983-01-01

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  9. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1982-02-09

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  10. High-pressure stabilization of argon fluorides.

    PubMed

    Kurzydłowski, Dominik; Zaleski-Ejgierd, Patryk

    2016-01-28

    On account of the rapid development of noble gas chemistry in the past half-century both xenon and krypton compounds can now be isolated in macroscopic quantities. The same does not hold true for the next lighter group 18 element, argon, which forms only isolated molecules stable solely in low temperature matrices or supersonic jet streams. Here we present theoretical investigations into a new high-pressure reaction pathway, which enables synthesis of argon fluorides in bulk and at room temperature. Our hybrid DFT calculations (employing the HSE06 functional) indicate that above 60 GPa ArF2-containing molecular crystals can be obtained by a reaction between argon and molecular fluorine. PMID:26742478

  11. Frequency doubling crystals

    DOEpatents

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  12. Contribution to the physicochemical rationale for the caries reducing effect of fluoride.

    PubMed

    Driessens, F C; Van Dijk, J W; Borggreven, J M; Verbeeck, R M

    1980-09-01

    The effect of fluoride on the stability of apatites containing Na+ and CO3(2)- ions is described qualitatively. Also the boundaries of the apatite stability field in the quasi-septary system CaO - P2O5 - H2O - Na2O - CO2 - NaF - MX are presented. At these boundaries brushite (or monetite), octocalciumphosphate, calcite and calcium fluoride can become stable solid phases. As a consequence, certain mechanisms for the caries reducing effect of fluoride gain probability over other proposed mechanisms. First, it is likely that endemic fluoride yields more fully mineralized enamel which in turn results in a lower initial rate of the caries process. Second, after eruption the mineral in the tooth superficial layer is bound to accumulate fluoride on the surface of its crystals. This causes a slower rate of the crystal surface dissolution at that site and, hence, a thicker and denser intact superficial layer over the lesion. Finally, the formation of a precipitate of fluorhydroxyapatite and perhaps also of calcium fluoride is promoted in the plaque during cycles of metabolic activity. Subsequent dissolution of the CaF2 and transformation of the fluorhydroxyapatite sets free Ca+ and F- ions. Both of these ions promote the remineralization of the lesion during periods of metabolic rest whereby brushite or monetite are transformed back into apatite.

  13. Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

    NASA Astrophysics Data System (ADS)

    Jiang, Yun; Liu, Yu-qin; Ma, Hong-wen; Zhou, Wei-gong

    2016-04-01

    The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300 °C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF2 were all approximately 26 pct, three times that of free CaF2, and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400 °C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300 °C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

  14. Chronic Fluoride Toxicity: Dental Fluorosis

    PubMed Central

    DenBesten, Pamela; Li, Wu

    2012-01-01

    Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2–3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enamel is caused by a hypomineralized enamel subsurface; with more severe dental fluorosis, pitting and a loss of the enamel surface occurs, leading to secondary staining (appearing as a brown color). Many of the changes caused by fluoride are related to cell/matrix/mineral interactions as the teeth are forming. At the early maturation stage, the relative quantity of amelogenin protein is increased in fluorosed enamel in a dose-related manner. This appears to result from a delay in the removal of amelogenins as the enamel matures. In vitro, when fluoride is incorporated into the mineral, more protein binds to the forming mineral, and protein removal by proteinases is delayed. This suggests that altered protein/mineral interactions are in part responsible for retention of amelogenins and the resultant hypomineralization that occurs in fluorosed enamel. Fluoride also appears to enhance mineral precipitation in forming teeth, resulting in hypermineralized bands of enamel, which are then followed by hypomineralized bands. Enhanced mineral precipitation with local increases in matrix acidity may affect maturation stage ameloblast modulation, potentially explaining the doserelated decrease in cycles of ameloblast modulation from ruffleended to smooth-ended cells that occur with fluoride exposure in rodents. Specific cellular effects of fluoride have been implicated, but more research is needed to determine which of these changes are relevant to the formation of fluorosed teeth. As

  15. Fluoride metabolism when added to salt.

    PubMed

    Whitford, Gary M

    2005-01-01

    The purpose of this review is to present the general characteristics of the metabolism of fluoride particularly as it occurs when ingested with fluoridated salt. Following the absorption of salt-borne fluoride from the stomach and intestines, its metabolism is identical to that of water-borne fluoride or other vehicles containing ionized fluoride. Because fluoridated salt is almost always ingested with food, however, absorption from the gastrointestinal tract may be delayed or reduced. Reports dealing with this subject have shown that fluoride absorption is delayed and, therefore, peak plasma concentrations are lower than when fluoride is ingested with water. The amount of ingested fluoride that is finally absorbed, however, is not appreciably affected unless the meal is composed mainly of components with high calcium concentrations. In this case, the extent of absorption can be reduced by as much as 50%. Fluoridated salt is also ingested less frequently than fluoridated water. Data are presented to show that the dose size and frequency of ingestion have only minor effects on fluoride retention in the body and on the concentrations in plasma, bone and enamel. Finally, calculations are presented to show that the risk of acute toxicity from fluoridated salt is virtually non-existent.

  16. Crystallization of BaF2-ZnF2-YbF3-ThF4 glass

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Doremus, Robert H.; Ko, Sen-Hou; Margraf, Tracey; Bansal, Narottam P.

    1988-01-01

    The phases and the rates of crystallization in a Ba-Zn-Yb-Th fluoride glass were studied using differential scanning calorimetry, XRD, and observational and chemical SEM analyses. The crystallizing phases that were identified included a BaYbTh fluoride, ZnF2, and YbF3. The BaYbTh fluoride crystallized first at about 450 C, and ZnF2, which was excluded from this phase, crystallized at its surfaces. At higher temperatures, the BaYbTh fluoride phase decomposed partially to BaThF6 and YbF3 phases.

  17. Lithium Battery Diaper Ulceration.

    PubMed

    Maridet, Claire; Taïeb, Alain

    2016-01-01

    We report a case of lithium battery diaper ulceration in a 16-month-old girl. Gastrointestinal and ear, nose, and throat lesions after lithium battery ingestion have been reported, but skin involvement has not been reported to our knowledge.

  18. Metal-ion-ligand interactions in thermotropic liquid crystals

    NASA Astrophysics Data System (ADS)

    Diehl, P.; Wasser, H. R.; Gowda, G. A. Nagana; Suryaprakash, N.; Khetrapal, C. L.

    1989-07-01

    The interactions of lithium perchlorate with ligands such as dimethyl sulphoxide, acetonitrile, pyridine and the Schiff base liquid crystals are investigated. The experiments open a new field for the study of metal-ion-ligand interactions in thermotropic liquid crystals.

  19. Mesoporous single crystals Li₄Ti₅O₁₂ grown on rGO as high-rate anode materials for lithium-ion batteries.

    PubMed

    Chen, Weina; Jiang, Hao; Hu, Yanjie; Dai, Yihui; Li, Chunzhong

    2014-08-18

    Mesoporous single crystals Li4Ti5O12 grown on reduced graphene oxide (MSCs-LTO-rGO) nanohybrids have been synthesized by a simple hydrothermal reaction of TiO2/rGO and LiOH with subsequent annealing in Ar at 600 °C, which exhibited high specific capacity (171 mA h g(-1)) with much improved rate capability (132 mA h g(-1) at 40 C) and intriguing cycling stability (85% capacity retention after 2000 cycles).

  20. Precise determination of full matrix of piezo-optic coefficients with a four-point bending technique: the example of lithium niobate crystals.

    PubMed

    Krupych, Oleg; Savaryn, Viktoriya; Vlokh, Rostyslav

    2014-04-01

    A recently proposed technique representing a combination of digital imaging laser interferometry with a classical four-point bending method is applied to a canonical nonlinear optical crystal, LiNbO₃, to precisely determine a full matrix of its piezo-optic coefficients (POCs). The contribution of a secondary piezo-optic effect to the POCs is investigated experimentally and analyzed theoretically. Based on the POCs thus obtained, a full matrix of strain-optic coefficients (SOCs) is calculated and the appropriate errors are estimated. A comparison of our experimental errors for the POCs and SOCs with the known reference data allows us to claim the present technique as the most precise.

  1. Reciprocated suppression of polymer crystallization toward improved solid polymer electrolytes: Higher ion conductivity and tunable mechanical properties

    SciTech Connect

    Bi, Sheng; Sun, Che-Nan; Zawodzinski, Thomas A.; Ren, Fei; Keum, Jong Kahk; Ahn, Suk-Kyun; Li, Dawen; Chen, Jihua

    2015-08-06

    Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl) imide and polymer matrix were extensively studied in the past due to their excellent potential in a broad range of energy related applications. Poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) are among the most examined polymer candidates as solid polymer electrolyte matrix. In this paper, we study the effect of reciprocated suppression of polymer crystallization in PVDF/PEO binary matrix on ion transport and mechanical properties of the resultant solid polymer electrolytes. With electron and X-ray diffractions as well as energy filtered transmission electron microscopy, we identify and examine the appropriate blending composition that is responsible for the diminishment of both PVDF and PEO crystallites. Laslty, a three-fold conductivity enhancement is achieved along with a highly tunable elastic modulus ranging from 20 to 200 MPa, which is expected to contribute toward future designs of solid polymer electrolytes with high room-temperature ion conductivities and mechanical flexibility.

  2. Controlled solvothermal synthesis and electrochemical performance of LiCoPO4 submicron single crystals as a cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wu, Borong; Xu, Hongliang; Mu, Daobin; Shi, Lili; Jiang, Bing; Gai, Liang; Wang, Lei; Liu, Qi; Ben, Liubin; Wu, Feng

    2016-02-01

    The submicron single crystals of LiCoPO4 with 500 nm diameter are prepared by solvothermal method. The carbon coated sample is obtained using sucrose as carbon source under 650 °C subsequently. It is investigated that the solvent composition has an effect on the morphology and the electrochemical performance of the cathode material. The as-prepared samples are characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopic, dynamic light scattering, and Fourier transform infrared spectra. The electrochemical performance is evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The LiCoPO4/C cathode can reach an initial discharge capacity of 123.8 mA h g-1 at 0.1C, with a retention of 83% after 100 cycles. A discharge capacity of 84.9 mA h g-1 is still attainable when the rate is up to 2C. The good cycling performance and rate capability are contributed to the decrease of particle size along with the lower antisite defect concentration in the LCP crystals, and uniform carbon coating.

  3. [Natural fluorides. The distinction between technically produced and naturally occurring fluorides in caries prophylaxis].

    PubMed

    Newesely, H

    1977-06-01

    In the controversial discussion of the bio-availability of fluoride in caries prophylaxis by fluoridation, fluorides coming from the geochemical circulation to the biochemical circulation are sometimes differentiated from synthetic fluorides introduced into fluoride medication. The question as to whether such a differentiation is essential can be answered from the physical-chemical point of view. This requires a wide field of scientific research starting with geochemistry and the knowledge of fluoride deposits, sedimentology, hydrology, technology of inorganic and organic fluorine compounds, thermodynamics of dissolved fluorides, up to biocrystallography and biochemistry of fluorine. PMID:267571

  4. High-fluoride groundwater.

    PubMed

    Rao, N Subba

    2011-05-01

    Fluoride (F(-)) is essential for normal bone growth, but its higher concentration in the drinking water poses great health problems and fluorosis is common in many parts of India. The present paper deals with the aim of establishment of facts of the chemical characteristics responsible for the higher concentration of F(-) in the groundwater, after understanding the chemical behavior of F(-) in relation to pH, total alkalinity (TA), total hardness (TH), carbonate hardness (CH), non-carbonate hardness (NCH), and excess alkalinity (EA) in the groundwater observed from the known areas of endemic fluorosis zones of Andhra Pradesh that have abundant sources of F(-)-bearing minerals of the Precambrians. The chemical data of the groundwater shows that the pH increases with increase F(-); the concentration of TH is more than the concentration of TA at low F(-) groundwater, the resulting water is represented by NCH; the TH has less concentration compared to TA at high F(-) groundwater, causing the water that is characterized by EA; and the water of both low and high concentrations of F(-) has CH. As a result, the F(-) has a positive relation with pH and TA, and a negative relation with TH. The operating mechanism derived from these observations is that the F(-) is released from the source into the groundwater by geochemical reactions and that the groundwater in its flowpath is subjected to evapotranspiration due to the influence of dry climate, which accelerates a precipitation of CaCO(3) and a reduction of TH, and thereby a dissolution of F(-). Furthermore, the EA in the water activates the alkalinity in the areas of alkaline soils, leading to enrichment of F(-). Therefore, the alkaline condition, with high pH and EA, and low TH, is a more conducive environment for the higher concentration of F(-) in the groundwater.

  5. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    DOEpatents

    Not Available

    1972-06-26

    It is an object of the invention to provide a primary cell or battery using ammonium fluoride--anhydrous hydrogen fluoride electrolyte having improved current and power production capabilities at low temperatures. It is operable at temperatures substantially above the boiling point of hydrogen fluoride. (GRA)

  6. The Effect of Fluoride in Osteoporosis.

    ERIC Educational Resources Information Center

    Hedlund, L. R.; Gallagher, J. C.

    1987-01-01

    This article discusses the effect of fluoride on bone tissue and the possible role of fluoride in the treatment of osteoporosis. At present, fluoride treatment should be restricted to clinical trials until its risks and benefits have been further evaluated. (Author/MT)

  7. A Manual for Rural School Fluoridation.

    ERIC Educational Resources Information Center

    Sprouse, Larman W.; Brooks, John

    The product of a 1972 Dental Health Branch contract with the U.S. Public Health Service, this manual is designed to aid in the development of school fluoridation programs and presents: background information on general concepts relating to the action of fluoride on teeth; discussions dealing with community and school fluoridation studies; and the…

  8. Lithium use in batteries

    USGS Publications Warehouse

    Goonan, Thomas G.

    2012-01-01

    Lithium has a number of uses but one of the most valuable is as a component of high energy-density rechargeable lithium-ion batteries. Because of concerns over carbon dioxide footprint and increasing hydrocarbon fuel cost (reduced supply), lithium may become even more important in large batteries for powering all-electric and hybrid vehicles. It would take 1.4 to 3.0 kilograms of lithium equivalent (7.5 to 16.0 kilograms of lithium carbonate) to support a 40-mile trip in an electric vehicle before requiring recharge. This could create a large demand for lithium. Estimates of future lithium demand vary, based on numerous variables. Some of those variables include the potential for recycling, widespread public acceptance of electric vehicles, or the possibility of incentives for converting to lithium-ion-powered engines. Increased electric usage could cause electricity prices to increase. Because of reduced demand, hydrocarbon fuel prices would likely decrease, making hydrocarbon fuel more desirable. In 2009, 13 percent of worldwide lithium reserves, expressed in terms of contained lithium, were reported to be within hard rock mineral deposits, and 87 percent, within brine deposits. Most of the lithium recovered from brine came from Chile, with smaller amounts from China, Argentina, and the United States. Chile also has lithium mineral reserves, as does Australia. Another source of lithium is from recycled batteries. When lithium-ion batteries begin to power vehicles, it is expected that battery recycling rates will increase because vehicle battery recycling systems can be used to produce new lithium-ion batteries.

  9. Ionic conductivity and transport properties of poly(vinylidene fluoride-co-hexafluoropropylene)-based solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Abreha, Merhawi; Subrahmanyam, A. R.; Siva Kumar, J.

    2016-08-01

    Polymer electrolytes containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and various concentrations of lithium triflate were prepared to determine the optimal polymer-salt composition for maximum ionic conductivity. Complex formation was ascertained from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) studies. The conductivity measurements reveal that the ionic conductivity of the polymer electrolytes containing various salt concentrations increases with temperature and obeys the Arrhenius rule. It is found that the electrolyte containing 25 wt.% of lithium triflate exhibits the highest room temperature conductivity. Moreover, Ionic transference measurements show predominance of ionic motion.

  10. Rechargeable lithium cell

    NASA Astrophysics Data System (ADS)

    Salomon, M.; Plichta, E. J.

    1984-09-01

    The general object of this invention is to provide an improved rechargeable lithium cell. A more specific object of the invention is to provide a rechargeable lithium cell having an improved low temperature performance and rate capability. It has now been found that the aformentioned objects can be attained using lithium as the anode, a solution of a lithium salt such as LiF6 or LiAlC14 in a mixed organic solvent as the electrolyte and a lithium intercalating cathode.

  11. METHOD OF PREPARING METAL FLUORIDES

    DOEpatents

    Katz, J.J.; Sheft, I.

    1959-08-11

    A method is presented for preparing the halides of elements which are relatively non-reactive with halogenating agents. The method involves reacting a mixture of an oxygen containing salt of a difficulty halogenated metal with an oxygen containing salt of an easily halogenated metal with a halogenating agent. Accordingly plutonium tetrafluoride is produced by reacting a mixture of plutonium dioxide and uranium octaoxide with bromine trifluoride. The reaction proceeds smoothly at moderate temperatures and the resulting plutonium trifluoride may be readily separated from many impurities which form volatile fluorides by volatilizing these volatile fluorides from the reaction chamber.

  12. Near and Mid-Infrared Emission Characteristics of Er³⁺/Tm³⁺/Ho³⁺-Doped LiYF₄ Single Crystals Excited by Laser Diode.

    PubMed

    Hu, Haoyang; Xia, Haiping; Wang, Peiyuan; Peng, Jiangtao; Zhang, Yuepin; Jiang, Haochuan; Chen, Baojiu

    2016-01-01

    Yttrium lithium fluoride (LiYF₄) single crystals triply doped with Er³⁺/Tm³⁺/Ho³⁺ are synthesized by a vertical Bridgman method. Absorption spectra, emission spectra, and decay curves are measured to investigate the luminescent properties of the crystals. Compared with Er³⁺ singly doped and Er³⁺/Tm³⁺ and Er³⁺/Ho³⁺ doubly doped LiYF₄ crystals, an intense emission around 2.7 µm can be obtained in the triply doped LiYF4 crystal under excitation of 980 nm laser diode. Meanwhile, the near infrared emission at 1.5 µm from Er³⁺ in the triply doped crystal is effectively reduced. The possible energy transfer processes and the luminescent mechanisms for enhancing emission at 2.7 µm and quenching emission at 1.5 µm in the Er³⁺/Ho³⁺/Tm³⁺ triply doped crystals are proposed. The large energy transfer efficiency of 82.0% and excellent optical transmission indicate that this Er³⁺/Tm³⁺/Ho³⁺ triply doped crystal can be considered as a promising material for a mid- infrared laser at 2.7 µm. PMID:27398482

  13. A scanning electron microscope investigation of calcium fluoride-like material deposited during topical fluoride exposure on sound human enamel in vitro.

    PubMed

    Cruz, R A; Rolla, G

    1994-10-01

    1. The morphological aspects of globules deposited in vitro when a NaF solution is applied to sound human enamel were studied by scanning electron microscopy. 2. Particles, presumably of calcium fluoride-like material, formed on the surfaces of an unerupted tooth and consisted of subunits showing a "cauliflower" appearance, indicating agglomeration of even smaller particles. The number and size of the crystals increased with time of exposure. 3. These particles represent highly resistant fluoride reservoirs and may be of clinical significance.

  14. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and "turn on" fluorescent sensors for fluoride anion sensing employing hydrogen bonding.

    PubMed

    Ashok Kumar, S L; Saravana Kumar, M; Sreeja, P B; Sreekanth, A

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques. PMID:23714188

  15. Thermophysical parameters of the LBO crystal

    SciTech Connect

    Grechin, Sergei G; Zuev, A V; Fokin, A S; Kokh, Aleksandr E; Moiseev, N V; Popov, Petr A; Sidorov, Aleksei A

    2010-08-27

    The thermophysical parameters (linear thermal expansion coefficients, thermal conductivities, and heat capacity) of the lithium triborate (LBO) crystal are measured and compared with previously published data. (nonlinear-optics phenomena)

  16. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    DOE PAGES

    Wang, Feng; Kim, Sung -Wook; Seo, Dong -Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Gratez, Jason

    2015-03-26

    In this study, transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3–4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2 = Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid–solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This findingmore » indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. In conclusion, although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries.« less

  17. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    PubMed Central

    Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Graetz, Jason

    2015-01-01

    Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3–4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2=Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid–solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries. PMID:25808876

  18. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    SciTech Connect

    Wang, Feng; Kim, Sung -Wook; Seo, Dong -Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Gratez, Jason

    2015-03-26

    In this study, transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3–4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2 = Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid–solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. In conclusion, although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries.

  19. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Graetz, Jason

    2015-03-01

    Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3-4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2=Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid-solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries.

  20. Fluoride in chilies from southwestern china.

    PubMed

    Li, Bo; Li, Shehong; Wang, Mingguo; Liu, Xiaojing; Zheng, Baoshan

    2008-10-01

    The purpose of this research is to investigate the fluoride contents in the chilies from southwest China and other countries in order to calculate the difference in fluoride levels in the fresh chilies. The standard method in China for analysis of fluoride in food (GB/T 5009.18-2003) was applied to determinate the fluoride content in chilies. By determining the fluoride content in 176 fresh chili samples from 77 counties in southwest China and 31 chili samples from other countries, the research not only aims to find the regularity of fluoride distribution in fresh chili, but also to determine the origin of fluoride in fresh chili in China compared with the foreign samples. The geometric mean of fluoride content in the fresh chili was 8.9 mg kg(-1) (dry weight, 176 samples, confidence level: 95%). According to the study on the contents of fluoride in fresh chili, it seems that the fluoride content standard for vegetables in GB2762-2005 in China is inappropriate for chili, and 24.7 mg kg(-1)(dry weight) and 5.2 mg kg(-1) (fresh weight) in recommend as the fluoride contaminated discrimination values for fresh chili.

  1. The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth

    NASA Astrophysics Data System (ADS)

    Li, Weiyang; Yao, Hongbin; Yan, Kai; Zheng, Guangyuan; Liang, Zheng; Chiang, Yet-Ming; Cui, Yi

    2015-06-01

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes.

  2. Kidney function and lithium concentrations of rats given an injection of lithium orotate or lithium carbonate.

    PubMed

    Smith, D F; Schou, M

    1979-03-01

    A recent study by Kling et al (1978) noted the finding of higher lithium concentrations in serum and brain of rats after an intraperitoneal injection (2 mmol lithium kg-1) of lithium orotate as a slurry than of lithium carbonate in solution. The authors suggested that lithium orotate might offer advantages in the treatment of patients. We repeated the experiments of Kling et al but in addition examined the kidney function of the rats. Glomerular filtration rate and urine flow were markedly lower in rats given lithium orotate than in rats given lithium carbonate, sodium chloride or a sham injection. The renal lithium clearance was significantly lower, the kidney weight and the lithium concentrations in serum, kidney and heart significantly higher after injection of lithium orotate than after injection of lithium carbonate. The higher lithium concentrations could be accounted for by the lower kidney function. It seems inadvisable to use lithium orotate for the treatment of patients. PMID:34690

  3. The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth.

    PubMed

    Li, Weiyang; Yao, Hongbin; Yan, Kai; Zheng, Guangyuan; Liang, Zheng; Chiang, Yet-Ming; Cui, Yi

    2015-01-01

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes. PMID:26081242

  4. The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth.

    PubMed

    Li, Weiyang; Yao, Hongbin; Yan, Kai; Zheng, Guangyuan; Liang, Zheng; Chiang, Yet-Ming; Cui, Yi

    2015-06-17

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes.

  5. Salt fluoridation in Germany since 1991.

    PubMed

    Schulte, Andreas G

    2005-01-01

    Since 1991, fluoridated salt has been on sale in household-size packages in Germany. Potassium or sodium fluoride is added to iodized salt until the fluoride concentration reaches 250 mg/kg. The use of fluoridated salt to prevent caries is officially recommended by the Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK) and several other associations and groups interested in public health. In the course of the past thirteen years, the market share of fluoridated and iodized domestic salt rose to 63.1% in Germany. However, this positive development must not obscure the fact that fluoridated and iodized salt is still not allowed to be used in restaurant or cafeteria kitchens. This restriction now needs to be revoked in view of the fact that many children, adolescents and adults take their main meals in cafeterias or restaurants. Scientific studies have demonstrated beyond doubt that using fluoridated and iodized salt in cafeteria kitchens poses no problem whatever.

  6. The role of fluoride in erosion therapy.

    PubMed

    Huysmans, Marie-Charlotte; Young, Alix; Ganss, Carolina

    2014-01-01

    The role of fluoride in erosion therapy has long been questioned. However, recent research has yielded positive results. In this chapter, an overview of the literature is provided regarding the application of fluorides in the prevention and treatment of erosion and erosive wear. The results are presented and discussed for different fluoride sources such as monovalent and polyvalent fluorides, and for different vehicles such as toothpastes, solutions and rinses, as well as varnishes and gels. It is concluded that fluoride applications are very likely to be of use in the preventive treatment of erosive wear. Most promising are high-concentration, acidic formulations and the polyvalent fluoride sources, with the best evidence available for stannous fluoride. However, the evidence base for clinical effectiveness is still small.

  7. Special Report: Fluoridation of Water.

    ERIC Educational Resources Information Center

    Hileman, Bette

    1988-01-01

    Reviews the controversy regarding water fluoridation in the United States during the last 50 years. Discusses the current status; benefits; and health risks including skeletal fluorosis, kidney disease, hypersensitivity, mutagenic effects, birth defects, and cancer. Presents statistics and anecdotal accounts. (CW)

  8. [Fluoride accumulation and distribution in mulberry insects near fluoride pollution sources].

    PubMed

    Chen, Yuyin; Lu, Shenggao

    2002-01-01

    Fluoride accumulation and the relative fluoride loading of different body parts in wild mulberry silkworm (Bombyx mandarina M.), mulberry geometrid (Pathonandria atrineata B.), and mulberry silkworm (Bombyx mori L.) near fluoride pollution sources were studied. Comparison of the fluoride content of insect bodies and mulberry leaves showed that insects collected from polluted sites had increased fluoride accumulation. The digestive tract of the insect had much higher fluoride content than the other parts of the body and was considered to be the important organ of fluoride accumulation. There were also wide differences in fluoride accumulation between different insect species within the same polluted site. The highly significantly correlation between fluoride contents of wild mulberry silkworm, mulberry geometrid, and mulberry silkworm with that of the mulberry leaves on which they were collected was found.

  9. PVDF-HFP/ether-modified polysiloxane membranes obtained via airbrush spraying as active separators for application in lithium ion batteries.

    PubMed

    Seidel, S M; Jeschke, S; Vettikuzha, P; Wiemhöfer, H-D

    2015-08-01

    Improved hybrid polymer electrolyte membranes are introduced based on ether-modified polysiloxanes and poly(vinylidene fluoride-co-hexafluoropropylene) yielding a safe separator membrane, which is able to be sprayed directly onto lithium ion battery active materials, with an active role for enhanced ion transport.

  10. Glycine hydrogen fluoride: Remarkable hydrogen bonding in the dimeric glycine glycinium cation

    NASA Astrophysics Data System (ADS)

    Fleck, M.; Ghazaryan, V. V.; Petrosyan, A. M.

    2010-12-01

    Crystals of glycine hydrogen fluoride (Gly·HF) were prepared from an aqueous solution containing stoichiometric quantities of the components. The crystal structure of Gly·HF was determined, IR and Raman spectra were registered and are discussed. Gly·HF crystallizes in the orthorhombic space group Pbca with Z = 32. The most remarkable feature of the structure is the existence of symmetric dimeric glycine-glycinium cations with short hydrogen bonds (O⋯O distance of 2.446 Å), charge-counterbalanced by hydrogen bifluoride (F sbnd H⋯F) - anions - in addition to the expected glycinium cations and fluoride anions. These results were compared with previously published data on crystals grown in the system glycine-HF-H 2O.

  11. The effect of fluoridation and its discontinuation on fluoride profiles in the alveolar bone of rat.

    PubMed

    Ohmi, Kyohei; Nakagaki, Haruo; Tsuboi, Shinji; Okumura, Akihiro; Sugiyama, Tomoko; Thuy, Tran Thu; Robinson, Colin

    2005-10-01

    We investigated the effect of fluoridation and its discontinuation on fluoride content in the alveolar portion of the mandible in rats. Drinking water with three different fluoride contents (0, 50, 100 ppmF) was given to rats for three different periods (4, 13 and 25 weeks). Fluoride concentrations were measured in the crest, the middle, and the apical parts of the alveolar bone and in the body of the mandible. Furthermore, after fluoridated drinking water was given to rats for 4 or 13 weeks, distilled water was given to them for 21 or 12 weeks respectively; and the effect of the discontinuation on fluoride profiles was investigated. Layer samples were analyzed by abrasive microsampling. Fluoride and phosphorus concentrations were determined by ion-specific electrode and colorimetric procedures, respectively. There was an increase in fluoride concentrations in the mandible in proportion to the fluoride content in the drinking water and the duration of fluoridation. After fluoridation was discontinued, fluoride concentrations in the surface layers of the mandible presented a decrease. Among the four different parts of the mandible, the upper part of the alveolar bone and the alveolar crest part presented the highest rates of reduction. The relative reduction rate of fluoride concentration was closely related to the duration of discontinuation. The alveolar crest was affected most by the discontinuation of fluoridation, presenting the greatest reduction.

  12. Density measurements of the lithium fluoride/lithium sulfide eutectic at high temperature

    NASA Astrophysics Data System (ADS)

    Lloyd, Charles L.; Gilbert, James B.

    1994-10-01

    A straightforward and reliable method to determine densities of molten salts at high temperatures was de-veloped by Janz and Lorenz several years ago.[1] This method was followed in order to determine the density of the LiF/Li2S eutectic[2] over the temperature range of 1176 to 1355 K in which the eutectic is liquid. The rel-ative lack of data for this eutectic is surprising given its potential usefulness in the study of advanced batteries'31 and electrowinning of metals from molten sulfides.[41] The method is based on the fact that a solid piece of metal of known volume suspended from a pan balance into a molten salt will weigh less than if it were sus-pended in air at the same temperature. This difference in weight measured in grams will be equal to the buoyant force of the liquid at that temperature. The density of the salt bath can then readily be determined by dividing this difference by the volume of the solid piece of metal that is immersed in the bath. The procedure can be re-peated to give density values over a range of temperatures.

  13. Structural diversity in lithium carbides

    NASA Astrophysics Data System (ADS)

    Lin, Yangzheng; Strobel, Timothy A.; Cohen, R. E.

    2015-12-01

    The lithium-carbon binary system possesses a broad range of chemical compounds, which exhibit fascinating chemical bonding characteristics, which give rise to diverse and technologically important properties. While lithium carbides with various compositions have been studied or suggested previously, the crystal structures of these compounds are far from well understood. In this work, we present the first comprehensive survey of all ground state (GS) structures of lithium carbides over a broad range of thermodynamic conditions, using ab initio density functional theory (DFT) crystal structure searching methods. Thorough searches were performed for 29 stoichiometries ranging from Li12C to LiC12 at 0 and 40 GPa. Based on formation enthalpies from optimized van der Waals density functional calculations, three thermodynamically stable phases (Li4C3 , Li2C2 , and LiC12) were identified at 0 GPa, and seven thermodynamically stable phases (Li8C , Li6C , Li4C , Li8C3 , Li2C , Li3C4 , and Li2C3 ) were predicted at 40 GPa. A rich diversity of carbon bonding, including monomers, dimers, trimers, nanoribbons, sheets, and frameworks, was found within these structures, and the dimensionality of carbon connectivity existing within each phase increases with increasing carbon concentration. We find that the well-known composition LiC6 is actually a metastable one. We also find a unique coexistence of carbon monomers and dimers within the predicted thermodynamically stable phase Li8C3 , and different widths of carbon nanoribbons coexist in a metastable phase of Li2C2 (Imm2). Interesting mixed sp2-sp3 carbon frameworks are predicted in metastable phases with composition LiC6.

  14. Fluoride in groundwater: toxicological exposure and remedies.

    PubMed

    Jha, S K; Singh, R K; Damodaran, T; Mishra, V K; Sharma, D K; Rai, Deepak

    2013-01-01

    Fluoride is a chemical element that is found most frequently in groundwater and has become one of the most important toxicological environmental hazards globally. The occurrence of fluoride in groundwater is due to weathering and leaching of fluoride-bearing minerals from rocks and sediments. Fluoride when ingested in small quantities (<0.5 mg/L) is beneficial in promoting dental health by reducing dental caries, whereas higher concentrations (>1.5 mg/L) may cause fluorosis. It is estimated that about 200 million people, from among 25 nations the world over, may suffer from fluorosis and the causes have been ascribed to fluoride contamination in groundwater including India. High fluoride occurrence in groundwaters is expected from sodium bicarbonate-type water, which is calcium deficient. The alkalinity of water also helps in mobilizing fluoride from fluorite (CaF2). Fluoride exposure in humans is related to (1) fluoride concentration in drinking water, (2) duration of consumption, and (3) climate of the area. In hotter climates where water consumption is greater, exposure doses of fluoride need to be modified based on mean fluoride intake. Various cost-effective and simple procedures for water defluoridation techniques are already known, but the benefits of such techniques have not reached the rural affected population due to limitations. Therefore, there is a need to develop workable strategies to provide fluoride-safe drinking water to rural communities. The study investigated the geochemistry and occurrence of fluoride and its contamination in groundwater, human exposure, various adverse health effects, and possible remedial measures from fluoride toxicity effects.

  15. Method of recycling lithium borate to lithium borohydride through diborane

    DOEpatents

    Filby, Evan E.

    1976-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a diborane intermediate to complete the recycle scheme.

  16. Alimentary fluoride intake in preschool children

    PubMed Central

    2011-01-01

    Background The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste. Methods Daily alimentary fluoride intake was measured in a group of 36 children with an average age of 4.75 years and an average weight of 20.69 kg at baseline, by means of a double plate method. This was repeated after six months. Parents recorded their child's diet over 24 hours and collected duplicated portions of food and beverages received by children during this period. Pooled samples of food and beverages were weighed and solid food samples were homogenized. Fluoride was quantitatively extracted from solid food samples by a microdiffusion method using hexadecyldisiloxane and perchloric acid. The content of fluoride extracted from solid food samples, as well as fluoride in beverages, was measured potentiometrically by means of a fluoride ion selective electrode. Results Average daily fluoride intake at baseline was 0.389 (SD 0.054) mg per day. Six months later it was 0.378 (SD 0.084) mg per day which represents 0.020 (SD 0.010) and 0.018 (SD 0.008) mg of fluoride respectively calculated per kg bw/day. When adding the values of unwanted fluoride intake from the toothpaste shown in the literature (0.17-1.21 mg per day) the estimate of the total daily intake of fluoride amounted to 0.554-1.594 mg/day and recalculated to the child's body weight to 0.027-0.077 mg/kg bw/day. Conclusions In the children studied, observed daily fluoride intake reached the threshold for safe fluoride intake. When adding the potential fluoride intake from swallowed toothpaste, alimentary intake reached the optimum range for daily fluoride intake. These results showed that

  17. Determining the optimal fluoride concentration in drinking water for fluoride endemic regions in South India.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva Ilango, S; Aditya, G

    2009-10-01

    Fluoride ion in drinking water is known for both beneficial and detrimental effects on health. The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through drinking water owing to more than 90% bioavailability. The objective of this study is to predict optimal fluoride level in drinking water for fluoride endemic regions by comprising the levels of fluoride and other water quality parameters in drinking water, prevalence of fluorosis, fluoride intake through water, food and beverages such as tea and coffee and also considering the progressive accumulation of fluoride in animal bones, by comparing with non fluoride endemic areas comprise of the same geological features with the aid of regression analysis. Result of this study shows that increase of fluoride level above 1.33 mg/l in drinking water increases the community fluorosis index (CFI) value more than 0.6, an optimum index value above which fluorosis is considered to be a public health problem. Regression plot between water fluoride and bone fluoride levels indicates that, every increase of 0.5mg/l unit of water fluoride level increases the bone fluoride level of 52 mg/kg unit within 2 to 3 years. Furthermore, the consumption of drinking water containing more than 0.65 mg/l of fluoride can raise the total fluoride intake per day more than 4 mg, which is the optimum fluoride dose level recommended for adults by the Agency for Toxic Substances and Disease Registry. From the result, the people in fluoride endemic areas in South India are advised to consume drinking water with fluoride level within the limit of 0.5 to 0.65 mg/l to avoid further fluorosis risk.

  18. Global affordability of fluoride toothpaste

    PubMed Central

    Goldman, Ann S; Yee, Robert; Holmgren, Christopher J; Benzian, Habib

    2008-01-01

    Objective Dental caries remains the most common disease worldwide and the use of fluoride toothpaste is a most effective preventive public health measure to prevent it. Changes in diets following globalization contribute to the development of dental caries in emerging economies. The aim of this paper is to compare the cost and relative affordability of fluoride toothpaste in high-, middle- and low-income countries. The hypothesis is that fluoride toothpaste is not equally affordable in high-, middle- and low-income countries. Methods Data on consumer prices of fluoride toothpastes were obtained from a self-completion questionnaire from 48 countries. The cost of fluoride toothpaste in high-, middle- and low-income countries was compared and related to annual household expenditure as well as to days of work needed to purchase the average annual usage of toothpaste per head. Results The general trend seems to be that the proportion of household expenditure required to purchase the annual dosage of toothpaste increases as the country's per capita household expenditure decreases. While in the UK for the poorest 30% of the population only 0.037 days of household expenditure is needed to purchase the annual average dosage (182.5 g) of the lowest cost toothpaste, 10.75 days are needed in Kenya. The proportion of annual household expenditure ranged from 0.02% in the UK to 4% in Zambia to buy the annual average amount of lowest cost toothpaste per head. Conclusion Significant inequalities in the affordability of this essential preventive care product indicate the necessity for action to make it more affordable. Various measures to improve affordability based on experiences from essential pharmaceuticals are proposed. PMID:18554382

  19. Chitosan-gold-Lithium nanocomposites as solid polymer electrolyte.

    PubMed

    Begum, S N Suraiya; Pandian, Ramanathaswamy; Aswal, Vinod K; Ramasamy, Radha Perumal

    2014-08-01

    Lithium micro batteries are emerging field of research. For environmental safety biodegradable films are preferred. Recently biodegradable polymers have gained wide application in the field of solid polymer electrolytes. To make biodegradable polymers films plasticizers are usually used. However, use of plasticizers has disadvantages such as inhomogenities in phases and mechanical instability that will affect the performance of Lithium micro batteries. We have in this research used gold nanoparticles that are environmentally friendly, instead of plasticizers. Gold nanoparticles were directly template upon chitosan membranes by reduction process so as to enhance the interactions of Lithium with the polymer. In this article, for the first time the characteristics of Chitosan-gold-Lithium nanocomposite films are investigated. The films were prepared using simple solution casting technique. We have used various characterization tools such as Small Angle Neutron Scattering (SANS), XRD, FTIR, Raman, FESEM, and AFM, Light scattering, Dielectric and electrical conductivity measurements. Our investigations show that incorporation of gold results in enhancement of conductivity in Lithium containing Chitosan films. Also it affects the dielectric characteristics of the films. We conclude through various characterization tools that the enhancement in the conductivity was due to the retardation of crystal growth of lithium salt in the presence of gold nanoparticles. A model is proposed regarding the formation of the new nanocomposite. The conductivity of these biodegradable films is comparable to those of the current inorganic Lithium micro batteries. This new chitosan-Au-Li nanocomposite has potential applications in the field of Lithium micro batteries.

  20. Li(x)FeF6 (x = 2, 3, 4) battery materials: structural, electronic and lithium diffusion properties.

    PubMed

    Schroeder, Melanie; Eames, Christopher; Tompsett, David A; Lieser, Georg; Islam, M Saiful

    2013-12-21

    Lithium iron fluoride materials have attracted recent interest as cathode materials for lithium ion batteries. The electrochemical properties of the high energy density Li(x)FeF6 (x = 2, 3, 4) materials have been evaluated using a combination of potential-based and DFT computational methods. Voltages of 6.1 V and 3.0 V are found for lithium intercalation from Li2FeF6 to α-Li3FeF6 and α-Li3FeF6 to Li4FeF6 respectively. The calculated density of states indicate that Li2FeF6 possesses metallic states that become strongly insulating after lithium intercalation to form α-Li3FeF6. The large energy gain associated with this metal-insulator transition is likely to contribute to the associated large voltage of 6.1 V. Molecular dynamics simulations of lithium diffusion in α-Li3FeF6 at typical battery operating temperatures indicate high lithium-ion mobility with low activation barriers. These results suggest the potential for good rate performance of lithium iron fluoride cathode materials.

  1. Dynamics of Fluoride Bioavailability in the Biofilms of Different Oral Surfaces after Amine Fluoride and Sodium Fluoride Application

    PubMed Central

    Naumova, Ella A.; Dickten, Christoph; Jung, Rico; Krauss, Florian; Rübesamen, Henrik; Schmütsch, Katharina; Sandulescu, Tudor; Zimmer, Stefan; Arnold, Wolfgang H.

    2016-01-01

    It was the aim of this study to investigate differences in fluoride bioavailability in different oral areas after the application of amine fluoride (AmF) and sodium fluoride (NaF). The null hypothesis suggested no differences in the fluoride bioavailability. The tongue coating was removed and biofilm samples from the palate, oral floor and cheeks were collected. All subjects brushed their teeth with toothpaste containing AmF or NaF. Specimens were collected before, as well as immediately after and at 30 and 120 minutes after tooth brushing. The fluoride concentration was determined. The area under the curve was calculated for each location and compared statistically. In the tongue coating, fluoride concentration increased faster after NaF application than after AmF application. After 30 minutes, the fluoride concentration decreased and remained stable until 120 minutes after AmF application and returned to baseline after NaF application. The difference between the baseline and the endpoint measurements was statistically significant. The fluoride concentration in the tongue coating remained at a higher level compared with the baseline for up to 120 minutes post-brushing. This may indicate that the tongue coating is a major reservoir for fluoride bioavailability. The results also indicate an unequal fluoride distribution in the oral cavity. PMID:26727989

  2. Domain switching kinetics in vinylidene fluoride/tetrafluoroethylene copolymer thin films

    NASA Astrophysics Data System (ADS)

    Nakagawa, Yuuta; Hashizume, Yoichiro; Nakajima, Takashi; Gruverman, Alexei; Okamura, Soichiro

    2016-10-01

    The local domain switching of vinylidene fluoride/tetrafluoroethylene copolymer thin films with different higher order structures was investigated by piezoresponse force microscopy. It was found that one-dimensionally grown domains were formed on highly crystallized needle-like crystals after local voltage pulse application. This is because each needle-like crystal consisted of parallel-stacked lamellae with chain folding along its major axis. In addition, it showed two-step domain growth processes, namely, inter lamella domain growth and the growth between lamellae. On the other hand, circular domains were formed on polycrystalline plate-like crystals and as-coated films.

  3. White light emission from Dy3+-doped LiLuF4 single crystal grown by Bridgman method

    NASA Astrophysics Data System (ADS)

    Dong, Yan-ming; Xia, Hai-ping; Fu, Li; Li, Shan-shan; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Zhang, Yue-pin; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-07-01

    Lithium lutetium fluoride (LiLuF4) single crystals doped with different Dy3+ ion concentrations were grown by Bridgman method. The Judd-Ofelt (J-O) strength parameters ( Ω 2, Ω 4, Ω 6) of Dy3+ in LiLuF4 crystal are calculated according to the measured absorption spectra and the J-O theory, by which the asymmetry of the Dy3+:LiLuF4 single crystal and the possibility of attaining stimulated emission from 4F9/2 level are analyzed. The capability of the Dy3+:LiLuF4 crystal in generating white light by simultaneous blue and yellow emissions under excitation with ultraviolet light is produced. The effects of excitation wavelength and doping concentration on chromaticity coordinates and photoluminescence intensity are also investigated. Favorable CIE coordinates, x=0.319 3 and y=0.349 3, can be obtained for Dy3+ ion in 2.701% molar doping concentration under excitation of 350 nm.

  4. Dipotassium hydrogencarbonate fluoride monohydrate

    PubMed Central

    Kahlenberg, Volker; Schwaier, Timo

    2013-01-01

    Single crystals of the title compound, K2(HCO3)F·H2O, were obtained as a secondary product after performing flux synthesis experiments aimed at the preparation of potassium rare earth silicates. The basic building unit of the structure is an [(HCO3)(H2O)F]2− zigzag chain running parallel to [001]. Both types of anions as well as the water mol­ecules reside on mirror planes perpendicular to [010] at y = 0.25 and y = 0.75, respectively. Linkage between the different constituents of the chains is provided by O—H⋯O and O—H⋯F hydrogen bonding. The K+ cations are located between the chains and are coordinated by two F and five O atoms in form of a distorted monocapped trigonal prism. PMID:23633982

  5. Lithium Redistribution in Lithium-Metal Batteries

    SciTech Connect

    Ferrese, A; Albertus, P; Christensen, J; Newman, J

    2012-01-01

    A model of a lithium-metal battery with a CoO2 positive electrode has been modeled in order to predict the movement of lithium in the negative electrode along the negative electrode/separator interface during cell cycling. A finite-element approach was used to incorporate an intercalation positive electrode using superposition, electrode tabbing, transport using concentrated solution theory, as well as the net movement of the lithium electrode during cycling. From this model, it has been found that movement of lithium along the negative electrode/separator interface does occur during cycling and is affected by three factors: the cell geometry, the slope of the open-circuit-potential function of the positive electrode, and concentration gradients in both the solid and liquid phases in the cell. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.027210jes] All rights reserved.

  6. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used... fluoride resins consist of basic resins produced by the polymerization of vinylidene fluoride. (b)...

  7. [Alternative ways of fluoride supplementation in childhood (author's transl)].

    PubMed

    Bergmann, K E; Bergmann, R L

    1977-02-01

    Fluorine is a nutritionally essential trace element. Fluoride concentration in drinking water of West Germany is very low, with rare exceptions. Fluoride intake with food therefore is inadequate. Consequently, for maintenance of normal dental health, fluoride has to be supplemented by some way. A number of methods of fluoride supplementation are being discussed in this paper and compared to drinking waster fluoridation.

  8. On the structure and morphology of poly (vinylidene fluoride) nanoscrolls

    NASA Astrophysics Data System (ADS)

    Burks, Gabriel; Gleeson, Sarah; Mei, Shan; Qi, Hao; Li, Christopher

    Beyond its widely popular piezoelectric effect and β-phase molecular conformation, poly (vinylidene fluoride) PVDF also offers great intrigue as it relates to understanding its intrinsic crystallization behavior and morphological preference. It has been suggested that the γ-phase of PVDF adopts a highly regular scrolling lamellar habit which can be attributed to small differences in the folding volume of atomic level hydrogen and fluorine atoms resulting in the evolution of highly curved polymer lamellae. To date this scrolled morphology of γ-phase PVDF has been witnessed via high temperature melt crystallization of crystalline thin films and via severe chemical etching of PVDF bulk films. Here we show the first growth of free-standing γ-phase PVDF scrolls via the solution crystallization technique. Differential scanning calorimetry (DSC), X-Ray Diffraction (XRD), Fourier Transformed-Infrared Spectroscopy (FT-IR), and Atomic Force Microscopy (AFM) have been used to both characterize and to further understand the fundamental preferred crystalline habit of the γ-phase of poly (vinylidene fluoride).

  9. Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries

    PubMed Central

    Carey, Clifton M.

    2014-01-01

    Declarative Title: Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. Background Fluoride is delivered to the teeth systemically or topically to aid in the prevention of dental caries. Systemic fluoride from ingested sources is in blood serum and can be deposited only in teeth that are forming in children. Topical fluoride is from sources such as community water, processed foods, beverages, toothpastes, mouthrinses, gels, foams, and varnishes. The United States Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) have proposed changes in their long standing recommendations for the amount of fluoride in community drinking water in response to concerns about an increasing incidence of dental fluorosis in children. Current research is focused on the development of strategies to improve fluoride efficacy. The purpose of this update is to inform the reader about new research and policies related to the use of fluoride for the prevention of dental caries. Methods Reviews of the current research and recent evidence based systematic reviews on the topics of fluoride are presented. Topics discussed include: updates on community water fluoridation research and policies; available fluoride in dentifrices; fluoride varnish compositions, use, and recommendations; and other fluoride containing dental products. This update provides insights into current research and discusses proposed policy changes for the use of fluoride for the prevention of dental caries. Conclusions The dental profession is adjusting their recommendations for fluoride use based on current observations of the halo effect and subsequent outcomes. The research community is focused on improving the efficacy of fluoride therapies thus reducing dental caries and lowering the amount of fluoride required for efficacy. PMID:24929594

  10. Fluoride retention in saliva and in dental biofilm after different home-use fluoride treatments.

    PubMed

    Souza, Daniela Correia Cavalcante; Maltz, Marisa; Hashizume, Lina Naomi

    2014-01-01

    This single-blind, randomized, crossover study aimed at assessing the long-term fluoride concentrations in saliva and in dental biofilm after different home-use fluoride treatments. The study volunteers (n = 38) were residents of an area with fluoridated drinking water. They were administered four treatments, each of which lasted for one week: twice-daily placebo dentifrice, twice-daily fluoride dentifrice, twice-daily fluoride dentifrice and once-daily fluoride mouthrinse, and thrice-daily fluoride dentifrice. At the end of each treatment period, samples of unstimulated saliva and dental biofilm were collected 8 h after the last oral hygiene procedure. Fluoride concentrations in saliva and dental biofilm were analyzed using a specific electrode. The fluoride concentrations in saliva and dental biofilm 8 h after the last use of fluoride products did not differ among treatments. The results of this study suggest that treatments with home-use fluoride products have no long-term effect on fluoride concentrations in saliva and in dental biofilm of residents of an area with a fluoridated water supply.

  11. Eukaryotic resistance to fluoride toxicity mediated by a widespread family of fluoride export proteins.

    PubMed

    Li, Sanshu; Smith, Kathryn D; Davis, Jared H; Gordon, Patricia B; Breaker, Ronald R; Strobel, Scott A

    2013-11-19

    Fluorine is an abundant element and is toxic to organisms from bacteria to humans, but the mechanisms by which eukaryotes resist fluoride toxicity are unknown. The Escherichia coli gene crcB was recently shown to be regulated by a fluoride-responsive riboswitch, implicating it in fluoride response. There are >8,000 crcB homologs across all domains of life, indicating that it has an important role in biology. Here we demonstrate that eukaryotic homologs [renamed FEX (fluoride exporter)] function in fluoride export. FEX KOs in three eukaryotic model organisms, Neurospora crassa, Saccharomyces cerevisiae, and Candida albicans, are highly sensitized to fluoride (>200-fold) but not to other halides. Some of these KO strains are unable to grow in fluoride concentrations found in tap water. Using the radioactive isotope of fluoride, (18)F, we developed an assay to measure the intracellular fluoride concentration and show that the FEX deletion strains accumulate fluoride in excess of the external concentration, providing direct evidence of FEX function in fluoride efflux. In addition, they are more sensitive to lower pH in the presence of fluoride. These results demonstrate that eukaryotic FEX genes encode a previously unrecognized class of fluoride exporter necessary for survival in standard environmental conditions. PMID:24173035

  12. Lithium purification technique

    DOEpatents

    Keough, R.F.; Meadows, G.E.

    1984-01-10

    A method for purifying liquid lithium to remove unwanted quantities of nitrogen or aluminum. The method involves precipitation of aluminum nitride by adding a reagent to the liquid lithium. The reagent will be either nitrogen or aluminum in a quantity adequate to react with the unwanted quantity of the impurity to form insoluble aluminum nitride. The aluminum nitride can be mechanically separated from the molten liquid lithium.

  13. Lithium purification technique

    DOEpatents

    Keough, Robert F.; Meadows, George E.

    1985-01-01

    A method for purifying liquid lithium to remove unwanted quantities of nitrogen or aluminum. The method involves precipitation of aluminum nitride by adding a reagent to the liquid lithium. The reagent will be either nitrogen or aluminum in a quantity adequate to react with the unwanted quantity of the impurity to form insoluble aluminum nitride. The aluminum nitride can be mechanically separated from the molten liquid lithium.

  14. Salivary fluoride levels after use of high-fluoride dentifrice.

    PubMed

    Vale, Glauber Campos; Cruz, Priscila Figueiredo; Bohn, Ana Clarissa Cavalcante Elvas; de Moura, Marcoeli Silva

    2015-01-01

    The aim of the study was to evaluate salivary fluoride (F) availability after toothbrushing with a high-F dentifrice. Twelve adult volunteers took part in this crossover and blind study. F concentration in saliva was determined after brushing with a high-F dentifrice (5000 µg F/g) or with a conventional F concentration dentifrice (1100 µg F/g) followed by a 15 mL distilled water rinse. Samples of nonstimulated saliva were collected on the following times: before (baseline), and immediately after spit (time = 0) and after 1, 2, 3, 4, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min. F analysis was performed with a fluoride-sensitive electrode and the area under curve of F salivary concentration × time (µg F/mL × min(-1)) was calculated. At baseline, no significant difference was found among dentifrices (P > 0.05). After brushing, both dentifrices caused an elevated fluoride level in saliva; however salivary F concentration was significantly higher at all times, when high-F dentifrice was used (P < 0.01). Even after 120 min, salivary F concentration was still higher than the baseline values for both dentifrices (P < 0.001). High-F dentifrice enhanced the bioavailability of salivary F, being an option for caries management in patients with high caries risk.

  15. Ferroelectric fluoride compositions and methods of making and using same

    DOEpatents

    Halasyamani, P Shiv; Chang, Hong-Young

    2015-04-07

    A method for synthesis of a ferroelectric material characterized by the general formula A.sub.xB.sub.yF.sub.z where A is an alkaline earth metal, B is transition metal or a main group metal, x and y each range from about 1 to about 5, and z ranges from about 1 to about 20 comprising contacting an alkaline earth metal fluoride, a difluorometal compound and a fluoroorganic acid in a medium to form a reaction mixture; and subjecting the reaction mixture to conditions suitable for hydrothermal crystal growth.

  16. Resistance switching in polyvinylidene fluoride (PVDF) thin films

    SciTech Connect

    Pramod, K.; Sahu, Binaya Kumar; Gangineni, R. B.

    2015-06-24

    Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents.

  17. Resistance switching in polyvinylidene fluoride (PVDF) thin films

    NASA Astrophysics Data System (ADS)

    Pramod, K.; Sahu, Binaya Kumar; Gangineni, R. B.

    2015-06-01

    Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents.

  18. Vapor phase deposition of transition metal fluoride glasses

    NASA Astrophysics Data System (ADS)

    Boulard, Brigitte; Jacoboni, Charles

    1991-08-01

    Multicomponent fluoride glasses in the PbF2-ZnF2-GaF3 (PZG) vitreous ternary system have been prepared by vapor phase deposition. The thermal stability of the deposited glass was improved by adding stabilizing agents (AlF3, NaF, LiF, InF3). The thin films, deposited on different substrates (fluoride glass, fluoride single crystal, metal, and silica glass) have been characterized by x-ray diffraction. Differential scanning calorimetry (DSC) and secondary ion mass spectroscopy (SIMS). The quality of the film, adherence, and homogeneity was controlled by scanning electronic microscopy (SEM). The optical characteristics of the film and PZG glass are given: the visible-infrared (VIS-IR) window is 0.3-8 micrometers and the refractive index 1.59+/- 0.2 depends on the lead content. Mn2+ doped films (up to 3 mole % MnF2) are optically active: Mn2+ exhibits a broad luminescence band at 560-570 nm (orange). The achieved film thickness varies from 0.5 to 80 micrometers , and the refractive index gradient approaches the required geometry for planar waveguides (doping of the film with lanthanides is in progress).

  19. Silicon oxidation in fluoride solutions

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.; Kapur, V.

    1980-01-01

    Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

  20. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    DOEpatents

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.