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Sample records for alkali aluminosilicate glasses

  1. Alkali aluminosilicate melts and glasses: structuring at the middle range order of amorphous matter

    NASA Astrophysics Data System (ADS)

    Le Losq, C.; neuville, D. R.

    2012-12-01

    Rheological properties of silicate melts govern both magma ascension from the mantle to the surface of the earth and volcanological eruptions styles and behaviours. It is well known that several parameters impact strongly these properties, such as for instance the temperature, pressure, chemical composition and volatiles concentration, finally influencing eruptive behaviour of volcanoes. In this work, we will focus on the Na2O-K2O-Al2O3-SiO2 system, which is of a prime importance because it deals with a non-negligible part of natural melts, like for instance the Vesuvius (Italy) or Erebus (Antartica) magmas. In an oncoming paper in Chemical Geology (Le Losq and Neuville, 2012), we have communicated results of the study of mixing Na-K in tectosilicate melts containing a high concentration of silica (≥75mol%). In the present communication, we will enlarge this first point of view to tectosilicate melts presenting a lower silica concentration. We will first present our viscosity data, and then the Adam and Gibbs theory that allows theoretically modelling Na-K mixing in aluminosilicate melts by using the so-called "mixed alkali effect". On the basis of the rheological results, the Na-K mixing cannot be explained with the ideal "mixed alkali effect", which involves random exchange of Na-K cationic pairs. To go further and as rheological properties are directly linked with structural properties, we will present our first results obtained by Raman and NMR spectroscopy. These last ones provide important structural pieces of information on the polymerization state of glasses and melts, and also on the environment of tetrahedrally coordinated cations. Rheological and structural results all highlight that Na and K are not randomly distributed in aluminosilicate glasses and melts networks. Na melts present a network with some channels and a non-random distribution of Al and Si. K networks are different. They also present a non-random distribution of Al and Si, but in two sub

  2. Ring distributions in alkali- and alkaline-earth aluminosilicate framework glasses- a raman spectroscopic study

    USGS Publications Warehouse

    Sharma, S.K.; Philpotts, J.A.; Matson, D.W.

    1985-01-01

    Raman spectra of crystalline polymorphs of a number of tectosilicate minerals having various sizes of smallest rings of TO4 tetrahedra (T = Si, Al) have been investigated to identify the bands that are sensitive indicators of the smallest rings in the network. The information obtained from the Raman spectra of tectosilicate minerals (e.g., SiO2 polymorphs, NaAlSi3O8 (Ab), NaAlSiO4 (Ne), KAlSi3O8 (Or), and KAlSi2O6 (Lc)) is used to interpret the Raman spectra of the isochemical glasses. It is shown that the frequency of the dominant ??s (TOT) band in the spectra of both crystals and glasses is related to the dominant size of TO4 rings in the structure. In agreement with previous X-ray RDF work, it is found that in the glasses of Ab and Jd (NaAlSi2O6) compositions, six-membered rings of TO4 tetrahedra predominate. The Raman spectrum of Or glass, however, indicates that clusters of intermixed four- and six-membered rings of TO4 tetrahedra, similar to those existing in crystalline leucite, are also present in the glass. Raman evidence indicates that four-membered rings of TO4 tetrahedra predominate in the glass of An composition. Similarly, the higher frequency of the ??s (TOT) band in the spectrum of Ne glass as compared with the frequency the ??s (TOT) band in the spectra of crystalline cargenieite and nephelite indicates either an admixture of the four- and six-membered rings or the puckering of six-membered rings in the glass structure. ?? 1985.

  3. Crystallization of Yttrium and Samarium Aluminosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Lago, Diana C.; Prado, Miguel O.

    Aluminosilicate glasses containing samarium and yttrium (SmAS and YAS glasses) exhibit high glass transition temperatures, corrosion resistance, and glass stability on heating which make them useful for technological applications. Yttrium aluminosilicate glass microspheres are currently being used for internal selective radiotherapy of liver cancer. During the preparation process, crystallization needs to be totally or partially avoided depending on the final application. Thus knowing the crystallization kinetics can help to prevent or avoid it, by designing a proper thermal pathway. In this work we studied the crystallization kinetics of YAS and SmAS glasses. It was found that both, YAS and SmAS glasses crystallize from the surface. SmAS glass presented lower densities of nucleation sites. The results also showed that the crystal growth apparent enthalpy is larger for SmAS glasses.

  4. Structure and Properties of Rare Earth Aluminosilicate Glasses.

    NASA Astrophysics Data System (ADS)

    Kohli, Jeffrey Todd

    1991-02-01

    Rare earth aluminosilicate (REAS) glasses have been formed using conventional melting techniques. The glass-forming regions of six different ternary systems have been defined with praseodymium, neodymium, samarium, terbium, erbium, or ytterbium oxides, with alumina and silica. The glass-forming regions systematically decreased in size as the atomic number of the particular rare earth in the ternary systems increased. Glasses, of the molar composition 2R_2O_3 -2Al_2O_3 -6SiO_2, were formed with twelve of the fourteen true rare earth oxides in order to investigate further effects related to the identity of the rare earth ion in the glasses. Several properties of the rare earth aluminosilicate glasses were measured. These properties include: thermal expansion, glass transformation temperature, dilatometric softening point, density, molar volume, index of refraction, Vicker's hardness, magnetic susceptibility and the Faraday rotatory response. The structures of rare earth aluminosilicate glasses were investigated using infrared and Raman spectroscopies as well as magic angle spinning nuclear magnetic resonance (MAS-NMR). MAS-NMR provided information regarding the local environments of silicon and aluminum ions in yttrium aluminosilicate (YAS) glasses. Since the size and valence of the yttrium ion are similar to the true rare earth ions, and the properties of the REAS and YAS glasses are similar, it is believed that the structures of yttrium aluminosilicate glasses are similar to those of the true rare earth aluminosilicate glasses. Several rare earth aluminogermanate glasses, having the molar formula 2R_2O _3-2Al_2O _3-6GeO_2, were also formed using conventional melting techniques. The properties of these glasses were compared and contrasted with those of the REAS glasses. Finally, a chapter on the study of magnetic susceptibility in common insulator glasses was added to the thesis. Several techniques used to measure magnetic susceptibility are reviewed in this chapter

  5. Aluminosilicate glass thin films elaborated by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Carlier, Thibault; Saitzek, Sébastien; Méar, François O.; Blach, Jean-François; Ferri, Anthony; Huvé, Marielle; Montagne, Lionel

    2017-03-01

    In the present work, we report the elaboration of aluminosilicate glass thin films by Pulsed Laser Deposition at various temperatures deposition. The amorphous nature of glass thin films was highlighted by Grazing Incidence X-Ray Diffraction and no nanocristallites were observed in the glassy matrix. Chemical analysis, obtained with X-ray Photoelectron Spectroscopy and Time of Flight Secondary Ion Mass Spectroscopy, showed a good transfer and homogeneous elementary distribution with of chemical species from the target to the film a. Structural studies performed by Infrared Spectroscopy showed that the substrate temperature plays an important role on the bonding configuration of the layers. A slight shift of Si-O modes to larger wavenumber was observed with the synthesis temperature, assigned to a more strained sub-oxide network. Finally, optical properties of thins film measured by Spectroscopic Ellipsometry are similar to those of the bulk aluminosilicate glass, which indicate a good deposition of aluminosilicate bulk glass.

  6. The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

    NASA Astrophysics Data System (ADS)

    Mysen, Bjorn O.

    2006-05-01

    Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe 3+ and Fe 2+ in meta-aluminosilicate glasses. Melts were formed at 1500 °C in equilibrium with air and quenched to glass in liquid H 2O with quenching rates exceeding 200 °C/s. The aluminosilicate compositions were NaAlSi 2O 6, Ca 0.5AlSi 2O 6, and Mg 0.5AlSi 2O 6. Iron oxide was added in the form of Fe 2O 3, NaFeO 2, CaFe 2O 4, and MgFe 2O 4 with total iron oxide content in the range ˜0.9 to ˜5.6 mol% as Fe 2O 3. The Mössbauer spectra, which were deconvoluted by assuming Gaussian distributions of the hyperfine field, are consistent with one absorption doublet of Fe 2+ and one of Fe 3+. From the area ratios of the Fe 2+ and Fe 3+ absorption doublets, with corrections for differences in recoil-fractions of Fe 3+ and Fe 2+, the Fe 3+/ΣFe is positively correlated with increasing total iron content and with decreasing ionization potential of the alkali and alkaline earth cation. There is a distribution of hyperfine parameters from the Mössbauer spectra of these glasses. The maximum in the isomer shift distribution function of Fe 3+, δFe 3+, ranges from about 0.25 to 0.49 mm/s (at 298 K relative to Fe metal) with the quadrupole splitting maximum, ΔFe 3+, ranging from ˜1.2 to ˜1.6 mm/s. Both δFe 3+ and δFe 2+ are negatively correlated with total iron oxide content and Fe 3+/ΣFe. The dominant oxygen coordination number Fe 3+ changes from 4 to 6 with decreasing Fe 3+/ΣFe. The distortion of the Fe 3+-O polyhedra of the quenched melts (glasses) decreases as the Fe 3+/ΣFe increases. These polyhedra do, however, coexist with lesser proportions of polyhedra with different oxygen coordination numbers. The δFe 2+ and ΔFe 2+ distribution maxima at 298 K range from ˜0.95 to 1.15 mm/s and 1.9 to 2.0 mm/s, respectively, and decrease with increasing Fe 3+/ΣFe. We suggest that these hyperfine parameter values for the most part are more consistent

  7. Crystallization of a barium-aluminosilicate glass

    NASA Technical Reports Server (NTRS)

    Drummond, C. H., III; Lee, W. E.; Bansal, N. P.; Hyatt, M. J.

    1989-01-01

    The crystallization of a celsian glass composition was investigated as a possible high-temperature ceramic matrix material. Heat treatments invariably resulted in crystallization of the hexaclesian phase unless a flux, such as lithia, was added or a nucleating agent used (e.g., celsian seeds). TEM analysis revealed complex microstructures. Glasses with Mo additions contained hexacelsian, mullite, and an Mo-rich glass. Li2O additions stabilized celsian but mullite and Mo-rich glass were still present.

  8. Modeling the Formation of Alkali Aluminosilicate Gels at the Mesoscale Using Coarse-Grained Monte Carlo.

    PubMed

    Yang, Kengran; White, Claire E

    2016-11-08

    Alkali-activated materials (AAMs) are currently being pursued as viable alternatives to conventional ordinary Portland cement because of their lower carbon footprint and established mechanical performance. However, our understanding of the mesoscale morphology (∼1 to 100 nm) of AAMs and related amorphous aluminosilicate gels, including the development of the three-dimensional aluminosilicate network and nanoscale porosity, is severely limited. This study investigates the structural changes that occur during the formation of AAM gels at the mesoscale by utilizing a coarse-grained Monte Carlo (CGMC) modeling technique that exploits density functional theory calculations. The model is capable of simulating the reaction of an aluminosilicate particle in a highly alkaline solution (sodium hydroxide or sodium silicate). Two precursor morphologies have been investigated (layered alumina and silica sheets mimicking metakaolin and spherical aluminosilicate particles reminiscent of coal-derived fly ash) to determine if the precursor morphology has an impact on the structural evolution of the resulting alkali-activated aluminosilicate gel. The CGMC model can capture the three major stages of the alkali-activation process-dissolution, polycondensation, and reorganization-revealing that the dissolved silicate and aluminate species, ranging from monomers to nanoprecipitates (100s of monomers in size), exist in the pore solution of the hardened gel. The model also reveals that the silica concentration of the activating solution controls the extent of dissolution of the precursor particle. From the analysis of the aluminosilicate cluster size distributions, the mechanisms of AAM gel growth have been elucidated, revealing that Ostwald ripening occurs in systems containing free silica at the start of the reaction. On the other hand, growth of the hydroxide-activated systems (metakaolin and fly ash) occurs via the formation of intermediate-sized clusters in addition to continual

  9. Effects of Thermal and Pressure Histories on the Chemical Strengthening of Sodium Aluminosilicate Glass

    NASA Astrophysics Data System (ADS)

    Svenson, Mouritz; Thirion, Lynn; Youngman, Randall; Mauro, John; Bauchy, Mathieu; Rzoska, Sylwester; Bockowski, Michal; Smedskjaer, Morten

    2016-03-01

    Glasses can be chemically strengthened through the ion exchange process, wherein smaller ions in the glass (e.g., Na+) are replaced by larger ions from a salt bath (e.g., K+). This develops a compressive stress (CS) on the glass surface, which, in turn, improves the damage resistance of the glass. The magnitude and depth of the generated CS depends on the thermal and pressure histories of the glass prior to ion exchange. In this study, we investigate the ion exchange-related properties (mutual diffusivity, CS, and hardness) of a sodium aluminosilicate glass, which has been densified through annealing below the initial fictive temperature of the glass or through pressure-quenching from the glass transition temperature at 1 GPa prior to ion exchange. We show that the rate of alkali interdiffusivity depends only on the density of the glass, rather than on the applied densification method. However, we also demonstrate that for a given density, the increase in CS and increase in hardness induced by ion exchange strongly depends on the densification method. Specifically, at constant density, the CS and hardness values achieved through thermal annealing are larger than those achieved through pressure-quenching. These results are discussed in relation to the structural changes in the environment of the network-modifier and the overall network densification.

  10. Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment.

  11. Thermodynamic assessment of hydrothermal alkali feldspar-mica-aluminosilicate equilibria

    USGS Publications Warehouse

    Sverjensky, D.A.; Hemley, J.J.; d'Angelo, W. M.

    1991-01-01

    The thermodynamic properties of minerals retrieved from consideration of solid-solid and dehydration equilibria with calorimetric reference values, and those of aqueous species derived from studies of electrolytes, are not consistent with experimentally measured high-temperature solubilities in the systems K2O- and Na2O-Al2O3-SiO2-H2O-HCl (e.g., K-fs - Ms - Qtz - K+ - H+). This introduces major inaccuracies into the computation of ionic activity ratios and the acidities of diagenetic, metamorphic, and magmatic hydrothermal fluids buffered by alkali silicate-bearing assemblages. We report a thermodynamic analysis of revised solubility equilibria in these systems that integrates the thermodynamic properties of minerals obtained from phase equilibria studies (Berman, 1988) with the properties of aqueous species calculated from a calibrated equation of state (Shock and Helgeson, 1988). This was achieved in two separate steps. First, new values of the free energies and enthalpies of formation at 25??C and 1 bar for the alkali silicates muscovite and albite were retrieved from the experimental solubility equilibria at 300??C and Psat. Because the latter have stoichiometric reaction coefficients different from those for solid-solid and dehydration equilibria, our procedure preserves exactly the relative thermodynamic properties of the alkali-bearing silicates (Berman, 1988). Only simple arithmetic adjustments of -1,600 and -1,626 (??500) cal/mol to all the K- and Na-bearing silicates, respectively, in Berman (1988) are required. In all cases, the revised values are within ??0.2% of calorimetric values. Similar adjustments were derived for the properties of minerals from Helgeson et al. (1978). Second, new values of the dissociation constant of HCl were retrieved from the solubility equilibria at temperatures and pressures from 300-600??C and 0.5-2.0 kbars using a simple model for aqueous speciation. The results agree well with the conductance-derived dissociation

  12. Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

    NASA Astrophysics Data System (ADS)

    Musil, Sean

    Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

  13. DuraLith Alkali-Aluminosilicate Geopolymer Waste Form Testing for Hanford Secondary Waste

    SciTech Connect

    Gong, W. L.; Lutz, Werner; Pegg, Ian L.

    2011-07-21

    The primary objective of the work reported here was to develop additional information regarding the DuraLith alkali aluminosilicate geopolymer as a waste form for liquid secondary waste to support selection of a final waste form for the Hanford Tank Waste Treatment and Immobilization Plant secondary liquid wastes to be disposed in the Integrated Disposal Facility on the Hanford Site. Testing focused on optimizing waste loading, improving waste form performance, and evaluating the robustness of the waste form with respect to waste variability.

  14. Selective laser densification of lithium aluminosilicate glass ceramic tapes

    NASA Astrophysics Data System (ADS)

    Zocca, Andrea; Colombo, Paolo; Günster, Jens; Mühler, Thomas; Heinrich, Jürgen G.

    2013-01-01

    Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane.

  15. Cellular morphology of organic-inorganic hybrid foams based on alkali alumino-silicate matrix

    NASA Astrophysics Data System (ADS)

    Verdolotti, Letizia; Liguori, Barbara; Capasso, Ilaria; Caputo, Domenico; Lavorgna, Marino; Iannace, Salvatore

    2014-05-01

    Organic-inorganic hybrid foams based on an alkali alumino-silicate matrix were prepared by using different foaming methods. Initially, the synthesis of an inorganic matrix by using aluminosilicate particles, activated through a sodium silicate solution, was performed at room temperature. Subsequently the viscous paste was foamed by using three different methods. In the first method, gaseous hydrogen produced by the oxidization of Si powder in an alkaline media, was used as blowing agent to generate gas bubbles in the paste. In the second method, the porous structure was generated by mixing the paste with a "meringue" type of foam previously prepared by whipping, under vigorous stirring, a water solution containing vegetal proteins as surfactants. In the third method, a combination of these two methods was employed. The foamed systems were consolidated for 24 hours at 40°C and then characterized by FTIR, X-Ray diffraction, scanning electron microscopy (SEM) and compression tests. Low density foams (˜500 Kg/m3) with good cellular structure and mechanical properties were obtained by combining the "meringue" approach with the use of the chemical blowing agent based on Si.

  16. Flux Decoupling and Chemical Diffusion in Redox Dynamics in Aluminosilicate Melts and Glasses (Invited)

    NASA Astrophysics Data System (ADS)

    Cooper, R. F.

    2010-12-01

    Measurements of redox dynamics in silicate melts and glasses suggest that, for many compositions and for many external environments, the reaction proceeds and is rate-limited by the diffusive flux of divalent-cation network modifiers. Application of ion-backscattering spectrometry either (i) on oxidized or reduced melts (subsequently quenched before analysis) or (ii) on similarly reacted glasses, both of basalt-composition polymerization, demonstrates that the network modifiers move relative to the (first-order-rigid) aluminosilicate network. Thus, the textures associated with such reactions are often surprising, and frequently include metastable or unstable phases and/or spatial compositional differences. This response is only possible if the motion of cations can be decoupled from that of anions. In many cases, decoupling is accomplished by the presence in the melt/glass of transition-metal cations, whose heterovalency creates distortions in the electronic band structure resulting in electronic defects: electron “holes” in the valence band or electrons in the conduction band. (The prevalence of holes or electrons being a function of bulk chemistry and oxygen activity.) These electronic species make the melt/glass a “defect semiconductor.” Because (a) the critical issue in reaction dynamics is the transport coefficient (the product of species mobility and species concentration) and (b) the electronic species are many orders of magnitude more mobile than are the ions, very low concentrations of transition-metal ions are required for flux decoupling. For example, 0.04 at% Fe keeps a magnesium aluminosilicate melt/glass a defect semiconductor down to 800°C [Cook & Cooper, 2000]. Depending on composition, high-temperature melts can see ion species having a high-enough transport coefficient to allow decoupling, e.g., alkali cations in a basaltic melt [e.g., Pommier et al., 2010]. In this presentation, these ideas will be illustrated by examining redox dynamics

  17. Mechanical-structural investigation of chemical strengthening aluminosilicate glass through introducing phosphorus pentoxide

    NASA Astrophysics Data System (ADS)

    Zeng, Huidan; Wang, Ling; Ye, Feng; Yang, Bin; Chen, Jianding; Chen, Guorong; Sun, Luyi

    2016-11-01

    Chemical strengthening of aluminosilicate glasses through K+-Na+ ion exchange has attracted tremendous attentions because of the accelerating demand for high strength and damage resistance glasses. However, a paramount challenge still exists to fabricate glasses with a higher strength and greater depth of ion-exchange layer. Herein, aluminosilicate glasses with different contents of P2O5 were prepared and the influence of P2O5 on the increased compressive stress and depth of ion-exchange layer was investigated by micro-Raman technique. It was noticed that the hardness, compressive stress, as well as the depth of ion-exchange layer substantially increased with an increasing concentration of P2O5 varied from 1 to 7 mol%. The obtained micro-Raman spectra confirmed the formation of relatively depolymerized silicate anions that accelerated the ion exchange. Phosphorus containing aluminosilicate glasses with a lower polymerization degree exhibited a higher strength and deeper depth of ion-exchange layer, which suggests that the phosphorus containing aluminosilicate glasses have promising applications in flat panel displays, windshields, and wafer sealing substrates.

  18. Fictive temperature-independent density and minimum indentation size effect in calcium aluminosilicate glass

    SciTech Connect

    Gross, T. M.; Tomozawa, M.

    2008-09-15

    Using the calcium aluminosilicate system a glass was developed that exhibits fictive temperature-independent density by creating an intermediate glass between normal and anomalous glasses. Normal glass, such as soda-lime silicate glass, exhibits decreasing density with increasing fictive temperature while anomalous glass, such as silica glass, exhibits increasing density with increasing fictive temperature. This intermediate glass composition was found to exhibit the minimum indentation size effect during indentation hardness testing. It appears that the indentation size effect is correlated with a deformation-induced fictive temperature increase, which is accompanied by a density change and hardness change in the vicinity of the indentation. It is suggested from these observations that indentation size effect originates from the energy required to create interfaces and defects such as shear bands, subsurface cracks, and point defects near the indenter-specimen boundary, which accompany the volume change.

  19. Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

    SciTech Connect

    White, Claire E.; Daemen, Luke L.; Hartl, Monika; Page, Katharine

    2015-01-15

    The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO{sub 2} alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C{sub 3}S), blended C{sub 3}S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C{sub 3}S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.

  20. Electric field-induced softening of alkali silicate glasses

    SciTech Connect

    McLaren, C.; Heffner, W.; Jain, H.; Tessarollo, R.; Raj, R.

    2015-11-02

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  1. White light emission from Sm3+/Tb3+ codoped oxyfluoride aluminosilicate glasses under UV light excitation

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, G.; Yang, R.; Qiu, J. R.; Brik, M. G.; Kumar, G. A.; Kityk, I. V.

    2009-01-01

    In this paper, we report on the absorption and photoluminescence properties of oxyfluoride aluminosilicate and boro-aluminosilicate glasses codoped with Sm3+ and Tb3+ ions. The differential thermal analysis profiles of these glasses have been obtained to confirm their thermal stability. From the measured absorption spectrum, Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4 and Ω6) have been evaluated for the Sm3+ ion. When excited by ultraviolet light these glasses emit a combination of blue, green and orange-red wavelengths forming white light. The ratio of the intensities of orange-red to green emissions can be tuned by varying both the concentration of the Sm3+ ion and the composition of the glass matrix. The excitation and emission spectra have shown a self-quenching effect for the Sm3+ ions and an efficient energy transfer from Tb3+ : 5D4 → Sm3+ : 4G5/2 was observed which was also confirmed by the decay lifetime measurements.

  2. A Novel Conversion Process for Waste Slag: The Preparation of Aluminosilicate Glass with Evaluation of the Dielectric Properties from Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Huang, Sanxi; Liu, Hongting; Wu, Fengnian; Chang, Ziyuan; Yue, Yunlong

    2015-11-01

    In this paper, aluminosilicate glass was prepared from blast furnace slag and quartz sand. Fourier transform infrared, differential scanning calorimetry and density measurements were carried out to investigate the effects of SiO2 on the aluminosilicate glass network rigidity. The results indicate that glass structure would be enhanced if more SiO2 was introduced into the glass system. Meanwhile, both the glass transition temperature ( T g) and the glass crystallization temperature ( T c) increase slightly; the increase in density of the glass being further evidence of the enhancement in glass network rigidity. Dielectric measurements show that the dielectric constant and dielectric loss decrease with more SiO2. The properties of the prepared aluminosilicate glasses are comparable to those of E glass, indicating that blast furnace slags are suitable for producing aluminosilicate glass with low dielectric constant and dielectric loss.

  3. Structure and properties of sodium aluminosilicate glasses from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Xiang, Ye; Du, Jincheng; Smedskjaer, Morten M.; Mauro, John C.

    2013-07-01

    Addition of alumina to sodium silicate glasses considerably improves the mechanical properties and chemical durability and changes other properties such as ionic conductivity and melt viscosity. As a result, aluminosilicate glasses find wide industrial and technological applications including the recent Corning® Gorilla® Glass. In this paper, the structures of sodium aluminosilicate glasses with a wide range of Al/Na ratios (from 1.5 to 0.6) have been studied using classical molecular dynamics simulations in a system containing around 3000 atoms, with the aim to understand the structural role of aluminum as a function of chemical composition in these glasses. The short- and medium-range structures such as aluminum coordination, bond angle distribution around cations, Qn distribution (n bridging oxygen per network forming tetrahedron), and ring size distribution have been systematically studied. In addition, the mechanical properties including bulk, shear, and Young's moduli have been calculated and compared with experimental data. It is found that aluminum ions are mainly four-fold coordinated in peralkaline compositions (Al/Na < 1) and form an integral part of the rigid silicon-oxygen glass network. In peraluminous compositions (Al/Na > 1), small amounts of five-fold coordinated aluminum ions are present while the concentration of six-fold coordinated aluminum is negligible. Oxygen triclusters are also found to be present in peraluminous compositions, and their concentration increases with increasing Al/Na ratio. The calculated bulk, shear, and Young's moduli were found to increase with increasing Al/Na ratio, in good agreement with experimental data.

  4. Striking role of non-bridging oxygen on glass transition temperature of calcium aluminosilicate glass-formers

    NASA Astrophysics Data System (ADS)

    Bouhadja, M.; Jakse, N.; Pasturel, A.

    2014-06-01

    Molecular dynamics simulations are used to study the structural and dynamic properties of calcium aluminosilicate, (CaO-Al2O3)1-x(SiO2)x, glass formers along three joins, namely, R = 1, 1.57, and 3, in which the silica content x can vary from 0 to 1. For all compositions, we determined the glass-transition temperature, the abundances of the non-bridging oxygen, triclusters, and AlO5 structural units, as well as the fragility from the temperature evolution of the α-relaxation times. We clearly evidence the role played by the non-bridging oxygen linked either to Al atoms or Si atoms in the evolution of the glass-transition temperature as well as of the fragility as a function of silica content along the three joins.

  5. Lithium and Sodium Resistance of Alkali Metal Vapor Resistant Glasses

    NASA Astrophysics Data System (ADS)

    Kishinevski, Anatoly; Hall, Matthew

    2014-05-01

    A common challenge in atomic physics is that of containing an alkali metal vapor at an elevated temperature and concurrently being able to excite and probe atomic transitions within. Typically glass is used as the material to construct the container, as it is easy to manipulate into any geometry and offers thermal, mechanical, and optical properties that no other material is capable. Unfortunately it has been well established that alkali metal gasses/vapors react readily with silica containing glass and results in a progressive darkening of the material. As the darkening reaction progresses, the optical transmission properties of the glass progressively degrade to an eventual point of uselessness. Alkali metals have been used extensively in frequency standards and magnetometers. The finite life of these alkali metal vapor-containing devices has been accepted despite varying attempts by different teams to solve this problem. As a viable solution, it has been identified there exist a family of glass compositions that contain a marginal amount of silica, may be lampworked using traditional glassblowing techniques, and that offer substantially better alkali vapor resistance. The evaluation of these glasses and their resistance to sodium and lithium vapor at varying pressures and temperatures are discussed.

  6. Crystallization, Microstructure, and Viscosity Evolutions in Lithium Aluminosilicate Glass-Ceramics

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Wheaton, Bryan; Geisinger, Karen; Credle, Allen; Wang, Jie

    2016-11-01

    Lithium aluminosilicate glass-ceramics have found widespread commercial success in areas such as consumer products, telescope mirrors, fireplace windows, etc. However, there is still much to learn regarding the fundamental mechanisms of crystallization, especially related to the evolution of viscosity as a function of the crystallization (ceramming) process. In this study, the impact of phase assemblage and microstructure on the viscosity was investigated using high temperature X-ray diffraction (HTXRD), beam bending viscometry (BBV), and transmission electron microscopy (TEM). Results from this study provide a first direct observation of viscosity evolution as a function of ceramming time and temperature. Sharp viscosity increases due to phase separation, nucleation and phase transformation are noticed through BBV measurement. A near-net shape ceramming can be achieved in TiO2-containing compositions by keeping the glass at a high viscosity (> 109 Pa.s) throughout the whole thermal treatment.

  7. Off-resonance nutation nuclear magnetic resonance study of framework aluminosilicate glasses with Li, Na, K, Rb or Cs as charge-balancing cation.

    PubMed

    Dirken, P J; Nachtegaal, G H; Kentgens, A P

    1995-11-01

    Framework aluminosilicate glasses with varying charge-balancing cation (Li, Na, K, Rb and Cs) have been studied with 27Al and 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) and 27Al on-resonance and off-resonance nutation NMR spectroscopy. This first application of off-resonance nutation NMR to disordered samples proves that it is a promising technique for the determination of mean quadrupole interactions in amorphous systems. Linewidths for Al decrease systematically with increasing size of the cation, due to a decrease in the quadrupole interaction from 5.0 MHz for the Li glass to 2.8 MHz for the Cs glass. A simple point-charge model effectively predicts the decrease in the quadrupole interaction. This indicates that the alkali ion is located close to aluminum. Looking at the residual linewidth after subtraction of the quadrupole broadening, the Al chemical shift distribution does not change significantly with the type of alkali ion. The same is true for the observed Si linewidth.

  8. Potential Applications of Alkali-Activated Alumino-Silicate Binders in Military Operations

    DTIC Science & Technology

    1985-11-01

    silica/alumina compounds ( cancrinites ) will not crystallize unless a template compound (sodium sulfate or nitrate) is present in solution to fill the...used in waste dis- posal. The compounds that form in low-temperature clay-alkali reactions (zeo- lites and cancrinites ) are large cage-like crystals that

  9. Synthesis and characterization of inorganic polymers from the alkali activation of an aluminosilicate

    NASA Astrophysics Data System (ADS)

    González, C. P.; Montaño, A. M.; González, A. K.; Ríos, C. A.

    2014-06-01

    This paper presents the results of the synthesis and characterization of inorganic polymers (IP) from aluminosilicates: bentonite (BT) and pumice (PP). The synthesis of IP, was carried out by two methods involving alkaline activation, at room temperature and 80 ± 5 °C, using as activating agent sodium silicate both commercial and analytical (Na2SiO3). Sodium hydroxide (NaOH) at 3 M, 7 M and 12 M was added. A lower degree of polymerization was obtained by using analytical precursors subjected to room temperature and 80 ± 5°C. Replacement of heating by the use of the commercial activating agent with greater alkalinity allows the formation of a 3D network. The materials were structurally characterized by FTIR spectroscopy with Attenuated Reflectance (ATR), Scanning Electron Microscope (SEM) and X -ray diffraction (DRX).

  10. Alkali-lead-iron phosphate glass and associated method

    DOEpatents

    Boatner, L.A.; Sales, B.C.; Franco, S.C.S.

    1994-03-29

    A glass composition and method of preparation utilizes a mixture consisting of phosphorus oxide within the range of about 40 to 49 molar percent, lead oxide within the range of about 10 to 25 molar percent, iron oxide within the range of about 10 to 17 molar percent and an alkali oxide within the range of about 23 to 30 molar percent. The glass resulting from the melting and subsequent solidifying of the mixture possesses a high degree of durability and a coefficient of thermal expansion as high as that of any of a number of metals. Such features render this glass highly desirable in glass-to-metal seal applications. 6 figures.

  11. Alkali-lead-iron phosphate glass and associated method

    DOEpatents

    Boatner, Lynn A.; Sales, Brian C.; Franco, Sofia C. S.

    1994-01-01

    A glass composition and method of preparation utilizes a mixture consisting of phosphorus oxide within the range of about 40 to 49 molar percent, lead oxide within the range of about 10 to 25 molar percent, iron oxide within the range of about 10 to 17 molar percent and an alkali oxide within the range of about 23 to 30 molar percent. The glass resulting from the melting and subsequent solidifying of the mixture possesses a high degree of durability and a coefficient of thermal expansion as high as that of any of a number of metals. Such features render this glass highly desirable in glass-to-metal seal applications.

  12. Optical Properties of Tm(3+) Ions in Alkali Germanate Glass

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Barnes, Norman P.; Reichle, Donald J.; Jiang, Shibin

    2006-01-01

    Tm-doped alkali germanate glass is investigated for use as a laser material. Spectroscopic investigations of bulk Tm-doped germanate glass are reported for the absorption, emission and luminescence decay. Tm:germanate shows promise as a fiber laser when pumped with 0.792 m diodes because of low phonon energies. Spectroscopic analysis indicates low nonradiative quenching and pulsed laser performance studies confirm this prediction by showing a quantum efficiency of 1.69.

  13. Room temperature tensile and fatigue properties of silicon carbide fiber-reinforced aluminosilicate glass

    SciTech Connect

    Zawada, L.P.; Butkus, L.M.; Hartman, G.A.

    1990-10-01

    Matrix-microcracking has been identified as an indicator of the onset of damage accumulation in ceramic matrix composites. Stress levels required to produce microcracking in unidirectional and cross-ply laminates of Nicalon-reinforced aluminosilicate glass were determined during monotonic tension testing. Specimens were then tested in tension-tension fatigue (R = 0.1) at stress levels ranging up to 250 percent of the matrix microcracking stress level. At high stress levels, the unidirectional specimens exhibited a sharp decrease in elastic modulus during the first 10,000 cycles, after which the modulus remained relatively constant until run-out occurred at a million cycles. Similar results were obtained from tests conducted on the cross-ply specimens. It is shown that for this material the fatigue life-limiting stress can be associated with the inelastic stress-strain behavior of those plies having fibers running parallel with the loading axis. 6 refs.

  14. Non-bridging Oxygen and Five-coordinated Aluminum in Aluminosilicate Glasses: A Cation Field Strength Study

    NASA Astrophysics Data System (ADS)

    Thompson, L. M.; Stebbins, J. F.

    2011-12-01

    Linda M. Thompson Jonathan F. Stebbins Dept. of Geological and Environmental Sciences, Stanford University, Stanford CA 94305 Although it is understood in aluminosilicate melts and glasses that non-bridging oxygens (NBO) have significant influence on thermodynamic and transport properties, questions remain about its role and the extent of its influence, particularly in metaluminous and peraluminous compositions. One major question persists regarding whether the formation of NBO is in any way coupled with the formation of VAl (AlO5), which is significantly impacted by cation field strength (defined as the cation charge divided by the square of the distance between the cation and oxygen atoms) (Kelsey et al., 2009). Previous work on calcium and potassium aluminosilicate glasses has shown the presence of NBO on the metaluminous join and persisting into the peraluminous region, with significantly more NBO present in Ca glasses compared to K glasses of similar composition (Thompson and Stebbins, 2011). However, it is unclear if there is any systematic impact on NBO content by cation field strength similar to the impact on VAl. Expanding on the previous study, barium aluminosilicate glasses were synthesized covering a range of compositions crossing the metaluminous (e.g. BaAl2O4-SiO2) join to observe changes in the NBO for comparison against the calcium aluminosilicate glasses, thus looking at the impact of cation size on NBO versus cation charge. In the barium glasses on the 30 mol% SiO2 isopleth, the highest NBO content was 6.9% for the barium rich glass (R = 0.51, where R is Ba2+ / (Ba2+ + 2Al3+)) while the most peraluminous glass (R = 0.45) had an NBO content of 1.9%. Comparison of these results to earlier data shows these numbers are similar to what is observed in the Ca glasses, indicating cation size alone does not have a significant impact on NBO content. However the VAl content does show a decrease (compared to calcium aluminosilicate glasses at similar R values

  15. Aluminosilicate melts and glasses at 1 to 3 GPa: temperature and pressure effects on recovered structural and density changes

    NASA Astrophysics Data System (ADS)

    Bista, S.; Stebbins, J. F.; Hankins, B.; Sisson, T. W.

    2013-12-01

    The effects of pressure on aluminosilicate melt and glass structure have been studied by both in-situ methods and by quenching and recovering glasses from high pressure and temperature. Significant increases in the coordination number of Al are now well known from the pressure range of 6-10 GPa. New results show that even at shallower mantle pressures of 1-3 GPa, typical aluminosilicate melts have significant concentrations of aluminum cations with coordination numbers greater than 4, with up to 10's of percents of AlO5 and AlO6. Here, we compare the densities and Al coordinations of glass samples recovered from piston-cylinder experiments carried out at 1 to 3 GPa and different temperatures. Samples of two different compositions (Ca3Al2Si6O18 and Na2Si3O7 with 0.5% Al2O3) were compressed and held at temperatures ranging from near to their ambient glass transitions (Tg) up to temperatures above the liquidus. Our 2 GPa sodium aluminosilicate and calcium aluminosilicate glasses quenched from near to Tg show about 5 and 6 percent recovered densification, respectively. In both compositions, samples that were quenched from above the melting point showed substantially lower recovered density and lower Al coordination number compared to the samples that were held near to Tg. For example, sodium aluminosilicate glass quenched from 510°C (near to Tg) had 70% more AlO5 than samples from 1200°C. Based on the measurement of actual cooling rates, fictive temperature differences for the glasses from these two extreme temperatures are not large enough to account for this apparent loss in density and Al-coordination during quench. The most likely cause for these differences is therefore probably the pressure drop during cooling from temperatures above liquidus, as the pressure medium does not respond quickly enough to the thermal contraction of the liquid and furnace parts to remain isobaric. Results from previous high T and P quenching studies thus give only minimum estimates

  16. The role of Al3+ on rheology and structural changes in sodium silicate and aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Le Losq, Charles; Neuville, Daniel R.; Florian, Pierre; Henderson, Grant S.; Massiot, Dominique

    2014-02-01

    Because of their importance in both the geosciences and the glass-making industry, alkali aluminosilicate melts have been the focal point of many past studies, but despite progress many problems remain unresolved, such as the complex behaviour of the thermodynamic properties of aluminium-rich alkali silicate melts. This paper presents a study of Na2O-Al2O3-SiO2 glasses and melts, containing 75 mol% SiO2 and different Al/(Al + Na) ratios. Their structure has been investigated by using Raman spectroscopy, as well as, 23Na, 27Al and 29Si 1D MAS NMR spectroscopy. Results confirm the role change of Na+ cations from network modifier to charge compensator in the presence of Al3+ ions. In addition, polymerization increases with increase of the Al/(Al + Na) ratio. These structural changes explain the observed variations in the viscosity of these melts. The viscosity data in turn allow us to calculate the configurational entropy of melts at the glass transition temperature [the Sconf(Tg)]. The variations of the Sconf(Tg) are strongly nonlinear, with sharp increases and decreases depending on the Al/(Al + Na) ratio. More importantly, a strong increase of the Sconf(Tg) is observed when a few Al2O3 is added to sodium silicate melt. A strong decrease is observed after crossing the tectosilicate join, when Al/(Al + Na) > 0.5 and when Al3+ ions are present in fivefold coordination, Al[5], in the glass. Furthermore, in situ27Al NMR spectra of the peraluminous melt show a clear increase of the Al[5] concentration with increasing temperature. When considered in combination with melt fragility and heat capacity, our data demonstrate that Al[5] is clearly a transient unit at high temperature in highly polymerized tectosilicate and peraluminous melts. However, when present in glasses, Al[5] increases the stability of the aluminosilicate network, hence the Tg of glasses. This could be explained by the ability of Al[5] to carry threefold coordinated oxygen atoms in its first coordination

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

    SciTech Connect

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

    2014-03-28

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

  18. Study of Alkali-Metal Vapor Diffusion into Glass Materials

    NASA Astrophysics Data System (ADS)

    Sato, Kiminori

    2013-08-01

    To investigate nanodispersion of alkali metals into glass materials, potassium vapor diffusion is conducted using SiO2 glass under well-controlled temperature conditions. It is found that potassium vapor significantly diffuses into the bulk of SiO2 glass with less precipitation on the surface when the host material is kept at a temperature slightly higher than that of the guest material. Positron annihilation spectroscopy reveals that angstrom-scale open spaces in the SiO2 matrix contribute to potassium vapor diffusion. The analysis of potassium concentration obtained by electron probe microanalysis (EPMA) mapping with Fick's second law yields an extremely low potassium diffusion coefficient of 5.1×10-14 cm2 s-1, which arises from the overall diffusion from open spaces of various sizes. The diffusion coefficient attributable to angstrom-scale open spaces is thus expected to be less than ˜10-14 cm2 s-1. The present findings imply that angstrom-scale open spaces play an important role in loading alkali metals into glass materials.

  19. Synthesis and studies on microhardness of alkali zinc borate glasses

    SciTech Connect

    Subhashini, Bhattacharya, Soumalya Shashikala, H. D. Udayashankar, N. K.

    2014-04-24

    The mixed alkali effect on zinc borate glasses have been reported. The glass systems of nominal composition 10Zn+xLi{sub 2}O+yNa{sub 2}O+80B{sub 2}O{sub 3} (x = y = 0, 5, 10, 15 mol%) were prepared using standard melt quenching method. The structural, physical and mechanical properties of the samples have been studied using X-ray diffraction(XRD), density measurement and Vickers hardness measurement, respectively. A consistent increase in the density was observed, which explains the role of the modifiers (Li{sub 2}O and Na{sub 2}O) in the network modification of borate structure. The molar volume is decreasing linearly with the alkali concentration, which is attributed to the conversion of tetrahedral boron (BO{sub 4/2}){sup −} into (BO{sub 3/2}){sup −}. The microhardness studies reveals the anisotropy nature of the material. It further confirms that the samples belong to hard glass category.

  20. Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

    NASA Astrophysics Data System (ADS)

    Srinivas, G.; Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.

    2016-05-01

    The mixed alkali and alkaline earth oxide borate glass with the composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-50B2O3 (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α02-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α02-), and (Λ) increases with increasing of K2O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K2O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).

  1. Structural, vibrational, and elastic properties of a calcium aluminosilicate glass from molecular dynamics simulations: The role of the potential

    SciTech Connect

    Bauchy, M.

    2014-07-14

    We study a calcium aluminosilicate glass of composition (SiO{sub 2}){sub 0.60}(Al{sub 2}O{sub 3}){sub 0.10}(CaO){sub 0.30} by means of molecular dynamics. To this end, we conduct parallel simulations, following a consistent methodology, but using three different potentials. Structural and elastic properties are analyzed and compared to available experimental data. This allows assessing the respective abilities of the potentials to produce a realistic glass. We report that, although all these potentials offer a reasonable glass structure, featuring tricluster oxygen atoms, their respective vibrational and elastic predictions differ. This allows us to draw some general conclusions about the crucial role, or otherwise, of the interaction potential in silicate systems.

  2. Structural, vibrational, and elastic properties of a calcium aluminosilicate glass from molecular dynamics simulations: the role of the potential.

    PubMed

    Bauchy, M

    2014-07-14

    We study a calcium aluminosilicate glass of composition (SiO2)0.60(Al2O3)0.10(CaO)0.30 by means of molecular dynamics. To this end, we conduct parallel simulations, following a consistent methodology, but using three different potentials. Structural and elastic properties are analyzed and compared to available experimental data. This allows assessing the respective abilities of the potentials to produce a realistic glass. We report that, although all these potentials offer a reasonable glass structure, featuring tricluster oxygen atoms, their respective vibrational and elastic predictions differ. This allows us to draw some general conclusions about the crucial role, or otherwise, of the interaction potential in silicate systems.

  3. Molecular dynamics simulation of alkali borate glass using coordination dependent potential

    SciTech Connect

    Park, B.; Cormack, A.N.

    1997-12-31

    The structure of sodium borate glass was investigated by molecular dynamics simulation using coordination dependent potential model. The simulated alkali borate glass consists of basic units, BO{sub 3} triangle, BO{sub 4} tetrahedra and structural groups such as boroxol ring and triborate units. The coordination of boron is converted from 3 to 4 by adding alkali oxide.

  4. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    DOEpatents

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  5. Fabrication of wound capacitors using flexible alkali-free glass

    DOE PAGES

    Wilke, Rudeger H. T.; Baker, Amanda; Brown-Shaklee, Harlan; ...

    2016-10-01

    Here, alkali-free glasses, which exhibit high energy storage densities (~35 J/cc), present a unique opportunity to couple high temperature stability with high breakdown strength, and thus provide an avenue for capacitor applications with stringent temperature and power requirements. Realizing the potential of these materials in kilovolt class capacitors with >1 J/cc recoverable energy density requires novel packaging strategies that incorporate these extremely fragile dielectrics. In this paper, we demonstrate the feasibility of fabricating wound capacitors using 50-μm-thick glass. Two capacitors were fabricated from 2.8-m-long ribbons of thin (50 μm) glass wound into 125-140-mm-diameter spools. The capacitors exhibit a capacitance ofmore » 70-75 nF with loss tangents below 1%. The wound capacitors can operate up to 1 kV and show excellent temperature stability to 150 °C. By improving the end terminations, the self-resonance can be shifted to above 1 MHz, indicating that these materials may be useful for pulsed power applications with microsecond discharge times.« less

  6. Fabrication of wound capacitors using flexible alkali-free glass

    SciTech Connect

    Wilke, Rudeger H. T.; Baker, Amanda; Brown-Shaklee, Harlan; Johnson-Wilke, Raegan; Hettler, Chad; Murata, Takashi; O'Malley, Patrick; Perini, Steve; Lanagan, Michael

    2016-10-01

    Here, alkali-free glasses, which exhibit high energy storage densities (~35 J/cc), present a unique opportunity to couple high temperature stability with high breakdown strength, and thus provide an avenue for capacitor applications with stringent temperature and power requirements. Realizing the potential of these materials in kilovolt class capacitors with >1 J/cc recoverable energy density requires novel packaging strategies that incorporate these extremely fragile dielectrics. In this paper, we demonstrate the feasibility of fabricating wound capacitors using 50-μm-thick glass. Two capacitors were fabricated from 2.8-m-long ribbons of thin (50 μm) glass wound into 125-140-mm-diameter spools. The capacitors exhibit a capacitance of 70-75 nF with loss tangents below 1%. The wound capacitors can operate up to 1 kV and show excellent temperature stability to 150 °C. By improving the end terminations, the self-resonance can be shifted to above 1 MHz, indicating that these materials may be useful for pulsed power applications with microsecond discharge times.

  7. Formation of alkali-metal nanoparticles in alkali-silicate glasses under electron irradiation and thermal processing

    NASA Astrophysics Data System (ADS)

    Bochkareva, E. S.; Sidorov, A. I.; Ignat'ev, A. I.; Nikonorov, N. V.; Podsvirov, O. A.

    2017-02-01

    Experiments and numerical simulation show that the irradiation of alkali-containing glasses using electrons at an energy of 35 keV and the subsequent thermal processing at a temperature above the vitrification point lead to the formation of spherical metal (lithium, sodium, and potassium) nanoparticles with oxide sheaths that exhibit plasmon resonances in the visible spectral range. Glasses containing two alkali metals exhibit mutual effect of metals on the formation of nanoparticles with two compositions due to the difference of ion radii and mobilities of metal ions.

  8. Investigation of Yb3+-doped alumino-silicate glasses for high energy class diode pumped solid state lasers

    NASA Astrophysics Data System (ADS)

    Körner, Jörg; Hein, Joachim; Tiegel, Mirko; Kuhn, Stefan; Buldt, Joachim; Yue, Fangxin; Seifert, Reinhard; Herrmann, Andreas; Rüssel, Christian; Kaluza, Malte C.

    2015-05-01

    We present a detailed investigation of different compositions of Yb3+-doped alumino-silicate glasses as promising materials for diode-pumped high-power laser applications at 1030 nm due to their beneficial thermo-mechanical properties. To generate comprehensive datasets for emission and absorption cross sections, the spectral properties of the materials were recorded at temperatures ranging from liquid nitrogen to room temperature. It was found that the newly developed materials offer higher emission cross sections at the center laser wavelength of 1030 nm than the so far used alternatives Yb:CaF2 and Yb:FP-glass. This results in a lower saturation fluence that offers the potential for higher laser extraction efficiency. Fluorescence lifetime quenching of first test samples was analyzed and attributed to the hydroxide (OH) concentration in the host material. Applying a sophisticated glass manufacturing process, OH concentrations could be lowered by up to two orders of magnitude, rising the lifetime and the quantum efficiency for samples doped with more than 6.1020 Yb3+ -ions per cm³. First laser experiments showed a broad tuning range of about 60 nm, which is superior to Yb:CaF2 and Yb:FP-glass in the same setup. Furthermore, measurements of the laser induced damage threshold (LIDT) for different coating techniques on doped substrates revealed the appropriateness of the materials for short pulse high-energy laser amplification.

  9. Aluminosilicate melts and glasses at 1 to 3 GPa: Temperature and pressure effects on recovered structural and density changes

    USGS Publications Warehouse

    Bista, S; Stebbins, Jonathan; Hankins, William B.; Sisson, Thomas W.

    2015-01-01

    In the pressure range in the Earth’s mantle where many basaltic magmas are generated (1 to 3 GPa) (Stolper et al. 1981), increases in the coordination numbers of the network-forming cations in aluminosilicate melts have generally been considered to be minor, although effects on silicon and particularly on aluminum coordination in non-bridging oxygen-rich glasses from the higher, 5 to 12 GPa range, are now well known. Most high-precision measurements of network cation coordination in such samples have been made by spectroscopy (notably 27Al and 29Si NMR) on glasses quenched from high-temperature, high-pressure melts synthesized in solid-media apparatuses and decompressed to room temperature and 1 bar pressure. There are several effects that could lead to the underestimation of the extent of actual structural (and density) changes in high-pressure/temperature melts from such data. For non-bridging oxygen-rich sodium and calcium aluminosilicate compositions in the 1 to 3 GPa range, we show here that glasses annealed near to their glass transition temperatures systematically record higher recovered increases in aluminum coordination and in density than samples quenched from high-temperature melts. In the piston-cylinder apparatus used, rates of cooling through the glass transition are measured as very similar for both higher and lower initial temperatures, indicating that fictive temperature effects are not the likely explanation of these differences. Instead, transient decreases in melt pressure during thermal quenching, which may be especially large for high initial run temperatures, of as much as 0.5 to 1 GPa, may be responsible. As a result, the equilibrium proportion of high-coordinated Al in this pressure range may be 50 to 90% greater than previously estimated, reaching mean coordination numbers (e.g., 4.5) that are probably high enough to significantly affect melt properties. New data on jadeite (NaAlSi2O6) glass confirm that aluminum coordination increase

  10. Fast dynamics of H{sub 2}O in hydrous aluminosilicate glasses studied with quasielastic neutron scattering

    SciTech Connect

    Indris, Sylvio; Heitjans, Paul; Behrens, Harald; Zorn, Reiner; Frick, Bernhard

    2005-02-01

    We studied the dynamics of dissolved water in aluminosilicate glasses with the compositions NaAlSi{sub 3}O{sub 8}{center_dot}0.3H{sub 2}O, NaAlSi{sub 3}O{sub 8}{center_dot}1.3H{sub 2}O and Ca{sub 0.5}AlSi{sub 3}O{sub 8}{center_dot}1.3H{sub 2}O using quasielastic neutron scattering. As shown by near-infrared spectroscopy on these samples, H{sub 2}O molecules are the predominant hydrous species in the water-rich glasses whereas OH groups bound to tetrahedrally coordinated cations are predominant at low water contents. Backscattering and time-of-flight methods were combined to investigate motional correlation times in the range between 0.2 ps and 2 ns. For the water-rich glasses an elastic scan between 2 K and 420 K shows that the dynamical processes set in at lower temperatures in the Ca-bearing glass than in the Na-bearing glass. This is corroborated by the broadening of the inelastic spectra S(Q,{omega}). The shape of the scattering function S(Q,t) suggests a distribution of activation barriers for the motion of hydrous species in the disordered structure of the glass. The distribution is narrower and the average activation energy is smaller in the Ca-bearing glass than in the Na-bearing glass. No indication for dynamics of hydrous species was found at temperatures up to 520 K in the water-poor glass NaAlSi{sub 3}O{sub 8}{center_dot}0.3H{sub 2}O containing dissolved water mainly in the form of OH groups. It is concluded that H{sub 2}O molecules are the dynamic species in the above-mentioned time regime in the water-rich glasses. The dynamic process is probably a rotation of H{sub 2}O molecules around their bisector axis.

  11. Alkali-aggregate reactivity of typical siliceious glass and carbonate rocks in alkali-activated fly ash based geopolymers

    NASA Astrophysics Data System (ADS)

    Lu, Duyou; Liu, Yongdao; Zheng, Yanzeng; Xu, Zhongzi; Shen, Xiaodong

    2013-08-01

    For exploring the behaviour of alkali-aggregate reactivity (AAR) in alkali-activated geopolymeric materials and assessing the procedures for testing AAR in geopolymers, the expansion behaviour of fly ash based geopolymer mortars with pure silica glass and typical carbonate rocks were studied respectively by curing at various conditions, i.e. 23°C and 38°C with relative humidity over 95%, immersed in 1M NaOH solution at 80°C. Results show that, at various curing conditions, neither harmful ASR nor harmful ACR was observed in geopolymers with the criteria specified for OPC system. However, with the change of curing conditions, the geopolymer binder and reactive aggregates may experience different reaction processes leading to quite different dimensional changes, especially with additional alkalis and elevated temperatures. It suggests that high temperature with additional alkali for accelerating AAR in traditional OPC system may not appropriate for assessing the alkali-aggregate reactivity behaviour in geopolymers designed for normal conditions. On the other hand, it is hopeful to control the dimensional change of geopolymer mortar or concrete by selecting the type of aggregates and the appropriate curing conditions, thus changing the harmful AAR in OPC into beneficial AAR in geopolymers and other alkali-activated cementitious systems.

  12. Communication: Dimensionality of the ionic conduction pathways in glass and the mixed-alkali effect.

    PubMed

    Novy, Melissa; Avila-Paredes, Hugo; Kim, Sangtae; Sen, Sabyasachi

    2015-12-28

    A revised empirical relationship between the power law exponent of ac conductivity dispersion and the dimensionality of the ionic conduction pathway is established on the basis of electrical impedance spectroscopic (EIS) measurements on crystalline ionic conductors. These results imply that the "universal" ac conductivity dispersion observed in glassy solids is associated with ionic transport along fractal pathways. EIS measurements on single-alkali glasses indicate that the dimensionality of this pathway D is ∼2.5, while in mixed-alkali glasses, D is lower and goes through a minimum value of ∼2.2 when the concentrations of the two alkalis become equal. D and σ display similar variation with alkali composition, thus suggesting a topological origin of the mixed-alkali effect.

  13. Thermal history effects on electrical relaxation and conductivity for potassium silicate glass with low alkali concentrations

    NASA Technical Reports Server (NTRS)

    Angel, Paul W.; Hann, Raiford E.; Cooper, Alfred R.

    1993-01-01

    Electrical response measurements from 10 Hz to 100 kHz between 120 and 540 C were made on potassium-silicate glasses with alkali oxide contents of 2, 3, 5 and 10 mol percent. Low alkali content glasses were chosen in order to try to reduce the Coulombic interactions between alkali ions to the point that frozen structural effects from the glass could be observed. Conductivity and electrical relaxation responses for both annealed and quenched glasses of the same composition were compared. Lower DC conductivity (sigma(sub DC)) activation energies were measured for the quenched compared to the annealed glasses. The two glasses with the lowest alkali contents exhibited a non-Arrhenius concave up curvature in the log(sigma(sub DC)) against 1/T plots, which decreased upon quenching. A sharp decrease in sigma(sub DC) was observed for glasses containing K2O concentrations of 5 mol percent or less. The log modulus loss peak (M'') maximum frequency plots against 1/T all showed Arrhenius behavior for both annealed and quenched samples. The activation energies for these plots closely agreed with the sigma(sub DC) activation energies. A sharp increase in activation energy was observed for both series as the potassium oxide concentration decreased. Changes in the electrical response are attributed to structural effects due to different alkali concentrations. Differences between the annealed and quenched response are linked to a change in the distribution of activation energies (DAE).

  14. Crystallization Kinetics of Barium and Strontium Aluminosilicate Glasses of Feldspar Composition

    NASA Technical Reports Server (NTRS)

    Hyatt, Mark J.; Bansal, Narottam P.

    1994-01-01

    Crystallization kinetics of BaO.Al2O3.2SiO2 (BAS) and SrO.Al2O3.2SiO2 (SAS) glasses in bulk and powder forms have been studied by non-isothermal differential scanning calorimetry (DSC). The crystal growth activation energies were evaluated to be 473 and 451 kJ/mol for bulk samples and 560 and 534 kJ/mol for powder specimens in BAS and SAS glasses, respectively. Development of crystalline phases on thermal treatments of glasses at various temperatures has been followed by powder x-ray diffraction. Powder samples crystallized at lower temperatures than the bulk and the crystallization temperature was lower for SAS glass than BAS. Crystallization in both glasses appeared to be surface nucleated. The high temperature phase hexacelsian, MAl2Si2O8 (M = Ba or Sr), crystallized first by nucleating preferentially on the glass surface. Also, monoclinic celsian does not nucleate directly in the glass, but is formed at higher temperatures from the transformation of the metastable hexagonal phase. In SAS the transformation to monoclinic celsian occurred rapidly after 1 h at 1100 C. In contrast, in BAS this transformation is sluggish and difficult and did not go to completion even after 10 h heat treatment at 1400 C. The crystal growth morphologies in the glasses have been observed by optical microscopy. Some of the physical properties of the two glasses are also reported.

  15. Osteogenic capacity of alkali-free bioactive glasses. In vitro studies.

    PubMed

    Brito, Ana F; Antunes, Brígida; Dos Santos, Francisco; Fernandes, Hugo R; Ferreira, José M F

    2016-08-16

    The high alkali content bioactive glasses commonly used to regenerate bone in dental, orthopedic, and maxillofacial surgeries induce some cytotoxicity in surrounding tissues. The present study aims the ability of some alkali-free bioactive glasses compositions, recently developed by our research group, to stimulate human mesenchymal stem cells (hMSCs) differentiation into osteoblasts in comparison to 45S5 Bioglass(®) . The obtained results demonstrated that alkali-free bioactive glasses possess higher stimulating towards differentiation of hMSCs in comparison to the control 45S5 Bioglass(®) . The von Kossa assay demonstrated that all bioactive glasses studied were able to induce the appearance of calcium deposits even when the cells were cultured in DMEM, proving that these biomaterials per se induce hMSCs cell differentiation. It was also observed that in both cell culture medium used (DMEM, and osteogenesis differentiation medium) alkali-free bioactive glasses clearly induced the appearance of more calcium deposits than the 45S5 Bioglass(®) , indicating their greater ability to induce cell differentiation. In summary, these results indicate that alkali-free bioactive glasses are a safe and valid alternative to 45S5 Bioglass(®) . © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  16. Effect of alkali addition on DC conductivity and thermal properties of vanadium-bismo-borate glasses

    SciTech Connect

    Khasa, S. Dahiya, M. S.; Agarwal, A.

    2014-04-24

    The DC Conductivity and Differential Thermal Analysis of glasses with composition (30−x)Li{sub 2}O⋅xV{sub 2}O{sub 5}⋅20Bi{sub 2}O{sub 3}⋅50B{sub 2}O{sub 3}(x=15, 10, 5) has been carried out in order to study the effect of replacing the Transition Metal Oxide (TMO) with alkali oxide. A significant increase in the DC conductivity has been observed with increase in alkali content. Again the thermal measurements have shown the decrease in both glass transition temperature (T{sub g}) and crystallization temperature (T{sub x}). The Glass Stability (GS) and Glass Forming Ability (GFA) have also been calculated and these also were found to decrease with increase in alkali oxide content at the cost of TMO.

  17. ``Cooperativity blockage'' in the mixed alkali effect as revealed by molecular-dynamics simulations of alkali metasilicate glass

    NASA Astrophysics Data System (ADS)

    Habasaki, Junko; Ngai, K. L.; Hiwatari, Yasuaki

    2004-07-01

    The relaxation dynamics of a complex interacting system can be drastically changed when mixing with another component having different dynamics. In this work, we elucidate the effect of the less mobile guest ions on the dynamics of the more mobile host ions in mixed alkali glasses by molecular-dynamics (MD) simulations. One MD simulation was carried out on lithium metasilicate glass with the guest ions created by freezing some randomly chosen lithium ions at their initial locations at 700 K. A remarkable slowing down of the dynamics of the majority mobile Li ions was observed both in the self-part of the density-density correlation function, Fs(k,t), and in the mean-squared displacements. On the other hand, there is no significant change in the structure. The motion of the Li ions in the unadulterated Li metasilicate glass is dynamically heterogeneous. In the present work, the fast and slow ions were divided into two groups. The number of fast ions, which shows faster dynamics (Lévy flight) facilitated by cooperative jumps, decreases considerably when small amount of Li ions are frozen. Consequently there is a large overall reduction of the mobility of the Li ions. The result is also in accordance with the experimental finding in mixed alkali silicate glasses that the most dramatic reduction of ionic conductivity occurs in the dilute foreign alkali limit. Similar suppression of the cooperative jumps is observed in the MD simulation data of mixed alkali system, LiKSiO3. Naturally, the effect found here is appropriately described as "cooperativity blockage." Slowing down of the motion of Li ions also was observed when a small number of oxygen atoms chosen at random were frozen. The effect is smaller than the case of freezing some the Li ions, but it is not negligible. The cooperativity blockage is also implemented by confining the Li metasilicate glass inside two parallel walls formed by freezing Li ions in the same metasilicate glass. Molecular-dynamics simulations

  18. Al coordination and water speciation in hydrous aluminosilicate glasses: direct evidence from high-resolution heteronuclear 1H-27Al correlation NMR.

    PubMed

    Xue, Xianyu; Kanzaki, Masami

    2007-02-01

    In order to shed light on the dissolution mechanisms of water in depolymerized aluminosilicate melts/glasses, a comprehensive one- (1D) and two-dimensional (2D) NMR study has been carried out on hydrous Ca- and Mg-aluminosilicate glasses of a haplobasaltic composition. The applied techniques include 1D 1H MAS NMR and 27Al-->1H cross-polarization (CP) MAS NMR, and 2D 1H NOESY and double-quantum (DQ) MAS NMR, 27Al triple-quantum (3Q) MAS NMR and 27Al-->1H heteronuclear correlation (HETCOR) and 3QMAS/HETCOR NMR. Ab initio calculations were also performed to place additional constraints on the 1H NMR characteristics of AlOH and Si(OH)Al groups. This study has revealed, for the first time, the presence of free OH (i.e. (Ca, Mg)OH), SiOH and AlOH species, in addition to molecular H2O, in hydrous glasses of a depolymerized aluminosilicate composition. The AlOH groups are mostly associated with four-coordinate Al, but some are associated with five- and six-coordinate Al.

  19. Influence of Y2O3 on the structure and properties of calcium magnesium aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    Mahdy, Ebrahim A.; Ibrahim, S.

    2012-11-01

    Glasses were prepared whose composition is defined by the formula: 25CaOsbnd 20MgOsbnd xY2O3sbnd (9-x) Al2O3sbnd 46SiO2 mol.% (0 ⩽ x ⩾ 3). To investigate the relation between the structural change and compositional variation by introducing Y2O3 instead of Al2O3, the glasses were analyzed by Fourier transform Infrared (FT-IR) analysis and differential thermal analysis (DTA). The density, molar volume, hardness and the chemical durability were measured and calculated. The FTIR spectra were recorded in the spectral range from 400 to 4000 cm-1 and showed significant depolymerization of silicate groups and hence resulting in a net decrease of local symmetry. Introducing yttrium in the glasses increases both glass transition (Tg) and softening (Ts) temperatures. The obtained Vicker's microhardness, the density values and the chemical stability data were increased by addition Y2O3 instead of Al2O3 in the glasses. The resulting data were greatly correlated to the role played by the cations present in the glass structure.

  20. Crystallization and properties of Sr-Ba aluminosilicate glass-ceramic matrices

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Hyatt, Mark J.; Drummond, Charles H., III

    1991-01-01

    Powders of roller quenched (Sr,Ba)O-Al2O3-2SiO2 glasses of various compositions were uniaxially pressed into bars and hot isostatically pressed at 1350 C for 4 hours or cold isostatically pressed and sintered at different temperatures between 800 to 1500 C for 10 or 20 hours. Densities, flexural strengths, and linear thermal expansion were measured for three compositions. The glass transition and crystallization temperatures were determined by Differential Scanning Calorimetry (DSC). The liquidus and crystallization temperature from the melt were measured using high temperature Differential Thermal Analysis (DTA). Crystalline phases formed on heat treatment of the glasses were identified by powder X ray diffraction. In Sr containing glasses, the monoclinic celsian phase always crystallized at temperatures above 1000 C. At lower temperatures, the hexagonal analog formed. The temperature for orthorhombic to hexagonal structural transformation increased monotonically with SrO content, from 327 C for BaO-Al2O3-2SiO2 to 758 C for SrO-Al2O3-2SiO2. These glass powders can be sintered to almost full densities and monoclinic celsian phase at a relatively low temperature of 1100 C.

  1. Structure of glasses containing transition metal ions. Progress report, February 1, 1979-January 31, 1980

    SciTech Connect

    White, W B; Furukawa, T; Tsong, I S.T.; Fox, K; Herman, J S; Houser, C; Nelson, C

    1980-02-01

    New normal coordinate calculations were used to relate the vibrational frequencies of silicate glasses to Si-O force constants. These appear to account for the observed frequency shifts with degree of silica polymerization. Raman spectroscopy has been used to elucidate the structure of sodium borosilicate glasses and of sodium aluminosilicate glasses. Structures of compositionally complex glasses can be understood if spectra are measured on many glasses spaced at small compositional intervals. Optical absorption spectra were used to investigate the structural setting of iron in alkali silicate glasses. Research on the alkali-hydrogen exchange in alkali silicate glasses was completed and additional work on ternary glasses is under way. A series of appendices present completed work on the structural investigations of alkali borosilicate glasses, on the structural setting of transition metal ions in glasses, and on the diffusion of hydrogen in alkali silicate glasses.

  2. Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam (Inventor)

    1992-01-01

    A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  3. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1995-01-01

    A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  4. Disorder and the extent of polymerization in calcium silicate and aluminosilicate glasses: O-17 NMR results and quantum chemical molecular orbital calculations

    NASA Astrophysics Data System (ADS)

    Lee, Sung Keun; Stebbins, Jonathan F.

    2006-08-01

    Estimation of the framework connectivity and the atomic structure of depolymerized silicate melts and glasses (NBO/T > 0) remains a difficult question in high-temperature geochemistry relevant to magmatic processes and glass science. Here, we explore the extent of disorder and the nature of polymerization in binary Ca-silicate and ternary Ca-aluminosilicate glasses with varying NBO/T (from 0 to 2.67) using O-17 NMR at two different magnetic fields of 9.4 and 14.1 T in conjunction with quantum chemical calculations. Non-random distributions among framework cations (Si and Al) are demonstrated in the variation of relative populations of oxygen sites with NBO/T. The proportion of non-bridging oxygen (NBO, Ca-O-Si) in the binary and ternary aluminosilicate glasses increases with NBO/T. While the trend is consistent with predictions from composition, the detailed fractions apparently deviate from the predicted values, suggesting further complications in the nature of polymerization. The proportion of each bridging oxygen in the glasses also varies with NBO/T. The fractions of Al-O-Si and Al-O-Al increase with increasing polymerization as CaO is replaced with Al 2O 3, while that of Si-O-Si seems to decrease, implying that activity of silica may decrease from calcium silicate to polymerized aluminosilicates (X=constant). Quantum chemical molecular orbital calculations based on density functional theory show that a silicate chain with Al-NBO (Ca-O-Al) has an energy penalty (calculated cluster energy difference) of about 108 kJ/mol compared with the cluster with Ca-O-Si, consistent with preferential depolymerization of Si-networks, reported in an earlier O-17 NMR study [Allwardt, J., Lee, S.K., Stebbins, J.F., 2003. Bonding preferences of non-bridging oxygens in calcium aluminosilicate glass: Evidence from O-17 MAS and 3QMAS NMR on calcium aluminate glass. Am. Mineral.88, 949-954]. These prominent types of non-randomness in the distributions suggest significant chemical

  5. Crystallization and properties of Sr-Ba aluminosilicate glass-ceramic matrices

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Hyatt, Mark J.; Drummond, Charles H., III

    1991-01-01

    Powders of roller quenched (Sr,Ba)O-Al2O3-2SiO2 glasses of various compositions were uniaxially pressed into bars and hot isostatically pressed at 1350 C for 4 hours or cold isostatically pressed and sintered at different temperatures between 800 to 1500 C for 10 or 20 hours. Densities, flexural strengths, and linear thermal expansion were measured for three compositions. The glasss transition and crystallization temperatures were determined by Differential Scanning Calorimetry (DSC). The liquidus and crystallization temperature from the melt were measured using high temperature Differential Thermal Analysis (DTA). Crystalline phases formed on heat treatment of the glasses were identified by powder x ray diffraction. In Sr containing glasses, the monoclinic celsian phase always crystallized at temperatures above 1000 C. At lower temperatures, the hexagonal analog formed. The temperature for orthorhombic to hexagonal structure transformation increased monotonically with SrO content, from 327 C for BaO-Al2O3-2SiO2 to 758 C for SrO-Al2O3-2SiO2. These glass powders can be sintered to almost full densities and monoclinic celsian phase at a relatively low temperature of 1100 C.

  6. PLUTONIUM SOLUBILITY IN HIGH-LEVEL WASTE ALKALI BOROSILICATE GLASS

    SciTech Connect

    Marra, J.; Crawford, C.; Fox, K.; Bibler, N.

    2011-01-04

    The solubility of plutonium in a Sludge Batch 6 (SB6) reference glass and the effect of incorporation of Pu in the glass on specific glass properties were evaluated. A Pu loading of 1 wt % in glass was studied. Prior to actual plutonium glass testing, surrogate testing (using Hf as a surrogate for Pu) was conducted to evaluate the homogeneity of significant quantities of Hf (Pu) in the glass, determine the most appropriate methods to evaluate homogeneity for Pu glass testing, and to evaluate the impact of Hf loading in the glass on select glass properties. Surrogate testing was conducted using Hf to represent between 0 and 1 wt % Pu in glass on an equivalent molar basis. A Pu loading of 1 wt % in glass translated to {approx}18 kg Pu per Defense Waste Processing Facility (DWPF) canister, or about 10X the current allowed limit per the Waste Acceptance Product Specifications (2500 g/m{sup 3} of glass or about 1700 g/canister) and about 30X the current allowable concentration based on the fissile material concentration limit referenced in the Yucca Mountain Project License Application (897 g/m{sup 3}3 of glass or about 600 g Pu/canister). Based on historical process throughput data, this level was considered to represent a reasonable upper bound for Pu loading based on the ability to provide Pu containing feed to the DWPF. The task elements included evaluating the distribution of Pu in the glass (e.g. homogeneity), evaluating crystallization within the glass, evaluating select glass properties (with surrogates), and evaluating durability using the Product Consistency Test -- Method A (PCT-A). The behavior of Pu in the melter was evaluated using paper studies and corresponding analyses of DWPF melter pour samples.The results of the testing indicated that at 1 wt % Pu in the glass, the Pu was homogeneously distributed and did not result in any formation of plutonium-containing crystalline phases as long as the glass was prepared under 'well-mixed' conditions. The

  7. On the Electron Paramagnetic Resonance Studies in Mixed Alkali Borate Glasses

    SciTech Connect

    Padmaja, G.; Reddy, T. Goverdhan; Kistaiah, P.

    2011-10-20

    Mixed alkali effect in oxide based glasses is one of the current research activity and studies on the behavior of spectroscopic parameters in these systems are quite important to understand the basic nature of this phenomenon. EPR studies of mixed alkali glasses Li{sub 2}O-K{sub 2}O-ZnO-B{sub 2}O{sub 3} doped with Fe{sup 3+} and Mn{sup 2+} were carried out at room temperature. The EPR spectra show typical resonances of d{sup 5} system (Fe{sup 3+} and Mn{sup 2+}) in all the measured glass specimens. Evaluated hyperfine constant, number of paramagnetic centers and paramagnetic susceptibility values show deviation from the linearity with the progressive substitution of the Li ion with K in glass network.

  8. Functionalized Amorphous Aluminosilicates

    NASA Astrophysics Data System (ADS)

    Mesgar, Milad

    Alkali treated aluminosilicate (geopolymer) was functionalized by surfactant to increase the hydrophobicity for making Pickering emulsion for the first part of this work. In the first part of this study, alkali treated metakaolin was functionalized with cetyltrimethylammonium bromide ((C16H33)N(CH 3)3Br, CTAB). The electrostatic interaction between this quaternary ammonium and the surface of the aluminosilicate which has negative charge has taken place. The particles then were used to prepare Pickering emulsion. The resulting stable dispersions, obtained very fast at very simple conditions with low ratio of aluminosilicate to liquid phase. In the second part, the interaction between geopolymer and glycerol was studied to see the covalent grafting of the geopolymer for making geopolymer composite. The composite material would be the basis material to be used as support catalyst, thin coating reagent and flame retardant material and so on, Variety of techniques, Thermogravimetric (TGA), Particle-induced X-ray emission (PIXE), FTIR, Solid state NMR, Powder X-ray diffraction (PXRD), BET surface area, Elemental analysis (CHN), TEM, SEM and Optical microscopy were used to characterize the functionalized geopolymer.

  9. Surface Morphology and Structure of Double-Phase Magnetic Alkali Borosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Andreeva, N. V.; Naberezhnov, A. A.; Tomkovich, M. V.; Nacke, B.; Kichigin, V.; Rudskoy, A. I.; Filimonov, A. V.

    2016-11-01

    The surface morphology of double-phase magnetic alkali borosilicate glasses of four types obtained by induction melting is studied by the methods of atomic-force and scanning electron microscopy. The distribution of elements over the surface and the elemental composition of the glasses are determined. It is shown that a dendritic system of interrelated channels required for formation of porous matrixes with controlled mean pore diameter may be obtained in these objects depending on the heat treatment mode.

  10. Development of chemical and topological structure in aluminosilicate liquids and glasses at high pressure

    NASA Astrophysics Data System (ADS)

    Drewitt, James W. E.; Jahn, Sandro; Sanloup, Chrystèle; de Grouchy, Charlotte; Garbarino, Gaston; Hennet, Louis

    2015-03-01

    The high pressure structure of liquid and glassy anorthite (CaAl2Si2O8) and calcium aluminate (CaAl2O4) glass was measured by using in situ synchrotron x-ray diffraction in a diamond anvil cell up to 32.4(2) GPa. The results, combined with ab initio molecular dynamics and classical molecular dynamics simulations using a polarizable ion model, reveal a continuous increase in Al coordination by oxygen, with 5-fold coordinated Al dominating at 15 GPa and a preponderance of 6-fold coordinated Al at higher pressures. The development of a peak in the measured total structure factors at 3.1 Å-1 is interpreted as a signature of changes in topological order. During compression, cation-centred polyhedra develop edge- and face- sharing networks. Above 10 GPa, following the pressure-induced breakdown of the network structure, the anions adopt a structure similar to a random close packing of hard spheres.

  11. EBSD and EDX analyses of a multiphase glass-ceramic obtained by crystallizing an yttrium aluminosilicate glass.

    PubMed

    Keshavarzi, Ashkan; Wisniewski, Wolfgang; Rüssel, Christian

    2013-09-11

    A glass with the mol % composition 23.82 Y2O3·39.82 Al2O3·28.50 SiO2·2.91AlF3·4.95 ZrO2 doped with 2 mol % CeF3 is crystallized at 1250 °C for 20 h. The crystallized samples are studied using X-ray diffraction (XRD), the SEM-based methods EBSD and EDX, as well as fluorescence microscopy. Six crystalline phases are detected in the residual glass including alumina, YAG, Y-stabilized zirconia (YSZ), and three different yttrium silicates of the composition Y2Si2O7. Chemistry-assisted indexing (ChI) is successfully applied to separate YAG and YSZ in EBSD-scans. YAG displays polygon as well as dendritic growth. Some crystals show both mechanisms at opposite ends, indicating that the growth mechanism is influenced by the chemistry of the surrounding glass matrix.

  12. On the induction of homogeneous bulk crystallization in Eu-doped calcium aluminosilicate glass by applying simultaneous high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Muniz, R. F.; de Ligny, D.; Le Floch, S.; Martinet, C.; Rohling, J. H.; Medina, A. N.; Sandrini, M.; Andrade, L. H. C.; Lima, S. M.; Baesso, M. L.; Guyot, Y.

    2016-06-01

    From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca3Mg(SiO4)2] and diopside [CaMgSi2O6]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f65d1 → 4f7 transition of Eu2+ was studied in both host systems. Additionally, the 5D0 → 7FJ transition of Eu3+ was used as an environment probe in the pristine glass and the glass-ceramic.

  13. Optical absorption and photoluminescence properties of Er3+ doped mixed alkali borate glasses.

    PubMed

    Ratnakaram, Y C; Kumar, A Vijaya; Naidu, D Tirupathi; Rao, J L

    2005-07-01

    An investigations of the optical absorption and fluorescence spectra of 0.2 mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3 x xLi2O(32-x)Na2O, 67.8B2O3 x xLi2O(32-x)K2O and 67.8B2O3 x xNa2O(32-x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950-1100 degrees C, 1.5-2 h) between two brass plates. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (xi(4f)) and configuration interaction (alpha) parameters are deduced as function of x. Using Judd-Ofelt theory, Judd-Ofelt intensity parameters (omega2, omega4 and omega6) are obtained. Radiative and non-radiative transition rates (A(T) and W(MPR)), radiative lifetimes (tauR), branching ratios (beta) and integrated absorption cross-sections (sigma) have been computed for certain excited states of Er3+ in these mixed alkali borate glasses. Emission spectra have been studied for all the three Er3+ doped mixed alkali borate glasses. The present paper throws light on the trends observed in the intensity parameters, radiative lifetimes, branching ratios and emission cross-sections as a function of x in these borate glasses, keeping in view the effect of mixed alkalies in borate glasses.

  14. A theoretical interpretation of the chemical shift of 29Si NMR peaks in alkali borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Nanba, Tokuro; Nishimura, Mitsunori; Miura, Yoshinari

    2004-12-01

    In 29Si-NMR, it has so far been accepted that the chemical shifts of Q n species (SiO 4 units containing n bridging oxygens) were equivalent between alkali borosilicate and boron-free alkali silicate glasses. In the sodium borosilicate glasses with low sodium content, however, a contradiction was confirmed in the estimation of alkali distribution; 11B NMR suggested that Na ions were entirely distributed to borate groups to form BO 4 units, whereas a -90 ppm component was also observed in 29Si-NMR spectra, which has been attributed to Q 3 species associated with a nonbridging oxygen (NBO). Then, cluster molecular orbital calculations were performed to interpret the -90 ppm component in the borosilicate glasses. It was found that a silicon atom which had two tetrahedral borons (B4) as its second nearest neighbors was similar in atomic charge and Si2p energy to the Q 3 species in boron-free alkali silicates. Unequal distribution of electrons in Si-O-B4 bridging bonds was also found, where much electrons were localized on the Si-O bonds. It was finally concluded that the Si-O-B4 bridges with narrow bond angle were responsible for the -90 ppm 29Si component in the borosilicate glasses. There still remained another interpretation; the Q 3 species were actually present in the glasses, and NBOs in the Q 3 species were derived from the tricluster groups, such as (O 3Si)O(BO 3) 2. In the glasses with low sodium content, however, it was concluded that the tricluster groups were not so abundant to contribute to the -90 ppm component.

  15. Structural and volume changes and their correlation in electron irradiated alkali silicate glasses

    NASA Astrophysics Data System (ADS)

    Gavenda, Tadeáš; Gedeon, Ondrej; Jurek, Karel

    2017-04-01

    Two binary alkali silicate glasses (15K2O·85SiO2 - denoted as K15 and 15Li2O·85SiO2 - denoted as Li15) were irradiated by 50 keV electron beams with doses within the range of 2.1-15.9 kC/m2. Volume changes induced by electron irradiation were monitored by means of Atomic Force Microscopy (AFM). Raman spectra were taken from the irradiated spots to observe structural changes. Volume compaction observed at lower doses was correlated with the increase of the D2 peak. Volume expansion at higher doses was related to migration of alkali ions. Irradiated glasses were annealed at 400 °C and 500 °C for 60 min. After annealing irradiated spots were again examined by AFM and Raman spectroscopy in order to determine volume and structural relaxation of radiation induced changes. Annealing at higher temperatures resulted in the levelling of the pits created by irradiation, but only for doses below incubation dose. The pits created by doses above incubation dose were not levelled. Annealing caused decrease of D2 peak and shift of the Si-O-Si vibrations band in direction to original structure. Low-frequency region of annealed Li15 glass was undistinguishable from that of pristine glass, while annealing of K15 glass did not result in the full reversion to the original shape. The differences between glasses were attributed to higher Tg of K15 glass. Q-motives bands of both glasses were not completely restored after annealing due to the absence of alkali ions.

  16. Influence of mixed alkalies on absorption and emission properties of Sm 3+ ions in borate glasses

    NASA Astrophysics Data System (ADS)

    Ratnakaram, Y. C.; Thirupathi Naidu, D.; Vijaya Kumar, A.; Gopal, N. O.

    2005-04-01

    The present work aims to study the variation of Judd-Ofelt intensity parameters, radiative transition probabilities, absorption and emission cross sections with alkali content in three different Sm 3+-doped mixed alkali borate glasses. Mixed alkali borate glasses in the composition 67H 3BO 3· xLi 2CO 3(32- x)Na 2CO 3·1Sm 2O 3, 67H 3BO 3· xLi 2CO 3(32- x)K 2CO 3·1Sm 2O 3 and 67H 3BO 3· xNa 2CO 3(32- x)K 2CO 3·1Sm 2O 3 with x=8, 12, 16, 20 and 24 mol% were prepared by quenching melts consisting of the above chemicals (850-950 °C, 1-2 h) between two brass plates. Judd-Ofelt theory is used to study the spectral properties and to calculate the radiative transition probabilities and branching ratios. The predicted radiative transition probabilities ( Aed), branching ratios ( β) and integrated absorption cross-sections ( Σ) for certain transitions are reported. From the emission spectra, emission cross-sections ( σ) are obtained for the four transitions, 4G 5/2→ 6H 5/2, 4G 5/2→ 6H 7/2, 4G 5/2→ 6H 9/2 and 4G 5/2→ 6H 11/2 of Sm 3+ ion in these mixed alkali borate glasses. Optical band gaps ( Eopt) and absorption edges are reported for the three Sm 3+-doped mixed alkali borate glasses.

  17. Structural features of alkali and barium aluminofluorophosphate glasses studied by IR spectroscopy

    SciTech Connect

    Urusovskaya, L.N.; Smirnova, E.V.

    1995-03-01

    IR reflection spectra of the Al(PO{sub 3}){sub 3}-MeF{sub x} glasses (Me=Li, Na, K, Ba) with the maximum content of fluoride varied for each specific glass within certain concentration limits are considered. Analysis of the spectra for glasses obtained upon variation in the content of alkali metal fluoride introduced into these glasses has demonstrated that the increase in the MeF{sub x} content leads to breaking the chain groupings and forming the [PO{sub 3}F]{sup 2-} groups, whereas the rise in concentration of barium fluoride in the Al(PO{sub 3}){sub 3}-BaF{sub 2} glasses brings about the stabilization of the chain structures.

  18. Nepheline crystallization in boron-rich alumino-silicate glasses as investigated by multi-nuclear NMR, Raman, & Mössbauer spectroscopies

    SciTech Connect

    Mccloy, John S.; Washton, Nancy M.; Gassman, Paul L.; Marcial, Jose; Weaver, Jamie L.; Kukkadapu, Ravi K.

    2015-02-01

    A spectroscopic study was conducted on 6 complex simulant nuclear waste glasses using multi-nuclear NMR, Raman and Mössbauer spectroscopies to explore the role of glass-forming elements Si, Al, B, along with Na and Fe and to understand their connectivity with the goal of understanding melt structure precursors to deleterious feldspathoid nepheline-like crystals formation. NMR showed the appearance of two sites for Al, Si, and Na in the samples which crystallized significant amounts of nepheline, and B speciation changed, typically resulting in more B(IV) after nepheline crystallization. Raman spectroscopy suggested a major part of the glass structure is composed of metaborate chains or rings, thus significant numbers of non-bridging oxygens and a separation of the borate from the alumino-silicate network. Mössbauer combined with Fe redox chemical measurements showed that Fe plays a minor role in these glasses, mostly as Fe3+, but that iron oxide spinel forms with nepheline in all cases. Models of the glass network, speciation of B, and allocation of non-bridging oxygens were computed. The Yun-Dell-Bray model failed to predict the observed high concentration of NBO necessary to explain the metaborate features in the Raman spectra, and it largely over-estimated B(IV) fraction. The model assuming Na-Al-Si moieties and using experimental B(IV) fraction predicted a large amount of NBO consistent with Raman spectra. An alternative notation for appreciating the glass network is suggested and then used to investigate the changes the glass due to crystallization of sodium nepheline and the residual glass network. From a theoretical standpoint, it may be preferred to picture nuclear waste glasses by the Lebedev theory of glass structure where “microcrystallites” of ordered nuclei (or embryos) exist in the matrix of more disordered glass.

  19. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses.

    PubMed

    Kansal, Ishu; Reddy, AlluAmarnath; Muñoz, Francisco; Choi, Seong-Jun; Kim, Hae-Won; Tulyaganov, Dilshat U; Ferreira, José M F

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO-MgO-SiO2-P2O5-CaF2 system. The (29)Si and (31)P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na2O/MgO ratios exhibit a silicate glass network with the dominance of Q(2)(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1h and 7 days while their chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Increasing Na(+)/Mg(2+) ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium.

  20. Raman Analysis of Perrhenate and Pertechnetate in Alkali Salts and Borosilicate Glasses

    SciTech Connect

    Gassman, Paul L.; McCloy, John S.; Soderquist, Chuck Z.; Schweiger, Michael J.

    2014-01-03

    Sodium borosilicate glasses containing various concentrations of rhenium or technetium were fabricated, and their vibrational spectra studied using a Raman microscope. Spectra were interpreted with reference to new high resolution measurements of alkali pertechnetates and perrhenates NaReO4, KReO4, NaTcO4, and KTcO4. At low concentrations of ReO4- or TcO4-, glass spectra show weak peaks superimposed on a dominant spectrum of glass characteristic of silicate and borate network vibrations. At high concentrations, sharp peaks characteristic of crystal field splitting and C4h symmetry dominate the spectra of glasses, indicating alkali nearby tetrahedral Re or Tc. Often peaks indicative of both the K and Na pertechnetates/ perrhenates are evident in the Raman spectrum, with the latter being favored at high additions of the source chemical, since Na is more prevalent in the glass and ion exchange takes place. These results have significance to immobilization of nuclear waste containing radioactive 99Tc in glass for ultimate disposal.

  1. Alkali-silica reactivity of expanded glass granules in structure of lightweight concrete

    NASA Astrophysics Data System (ADS)

    Bumanis, G.; Bajare, D.; Locs, J.; Korjakins, A.

    2013-12-01

    Main component in the lightweight concrete, which provides its properties, is aggregate. A lot of investigations on alkali silica reaction (ASR) between cement and lightweight aggregates have been done with their results published in the academic literature. Whereas expanded glass granules, which is relatively new product in the market of building materials, has not been a frequent research object. Therefore lightweight granules made from waste glass and eight types of cement with different chemical and mineralogical composition were examined in this research. Expanded glass granules used in this research is commercially available material produced by Penostek. Lightweight concrete mixtures were prepared by using commercial chemical additives to improve workability of concrete. The aim of the study is to identify effect of cement composition to the ASR reaction which occurs between expanded glass granules and binder. Expanded glass granules mechanical and physical properties were determined. In addition, properties of fresh and hardened concrete were determined. The ASR test was processed according to RILEM AAR-2 testing recommendation. Tests with scanning electron microscope and microstructural investigations were performed for expanded glass granules and hardened concrete specimens before and after exposing them in alkali solution.

  2. Alkali-free bioactive glasses for bone tissue engineering: a preliminary investigation.

    PubMed

    Goel, Ashutosh; Kapoor, Saurabh; Rajagopal, Raghu Raman; Pascual, Maria J; Kim, Hae-Won; Ferreira, José M F

    2012-01-01

    An alkali-free series of bioactive glasses has been designed and developed in the glass system CaO-MgO-SiO(2)-P(2)O(5)-CaF(2) along the diopside (CaMgSi(2)O(6))-fluorapatite (Ca(5)(PO(4))(3)F)-tricalcium phosphate (3CaO·P(2)O(5)) join. The silicate network in all the investigated glasses is predominantly coordinated in Q(2) (Si) units, while phosphorus tends to remain in an orthophosphate (Q(0)) environment. The in vitro bioactivity analysis of glasses has been made by immersion of glass powders in simulated body fluid (SBF) while chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Some of the investigated glasses exhibit hydroxyapatite formation on their surface within 1-12 h of their immersion in SBF solution. The sintering and crystallization kinetics of glasses has been investigated by differential thermal analysis and hot-stage microscopy, respectively while the crystalline phase evolution in resultant glass-ceramics has been studied in the temperature range of 800-900°C using powder X-ray diffraction and scanning electron microscopy. The alkaline phosphatase activity and osteogenic differentiation for glasses have been studied in vitro on sintered glass powder compacts using rat bone marrow mesenchymal stem cells. The as-designed glasses are ideal candidates for their potential applications in bone tissue engineering in the form of bioactive glasses as well as glass/glass-ceramic scaffolds.

  3. Effect of aluminum on the formation of silver metal quantum dots in sol-gel derived alumino-silicate glass film.

    PubMed

    Kim, Bok Hyeon; Son, Dong Hoon; Ju, Seongmin; Jeong, Chaehwan; Boo, Seongjae; Kim, Cheol Jin; Hanl, Won-Taek

    2006-11-01

    The effect of aluminum incorporation on silver metal quantum dots formation in the alumino-silicate glass film processed by sol-gel process was investigated. The sol-gel derived glass was coated onto the silica glass plate by spin coating with the mixture solution of tetraethyl orthosilicate (TEOS), C2H5OH, H2O, AgNO3, Al(NO3)3. 39H2O, and HNO3 with the molar ratios of Ag/Si = 0.12 and Al/Si varying from 0 to 0.12. The formation of the silver metal quantum dots was confirmed by the measurements of the UV/VIS optical spectra, the X-ray diffraction patterns, and the transmission electron microscope images. While the radius of silver metal quantum dots increased with the increase of aluminum concentration, the concentration of the silver metal quantum dots decreased. The formation of the silver metal quantum dots was found strongly suppressed by incorporation of aluminum ions in the glass. The change in the glass structure due to the aluminum incorporation was investigated by the analysis of the Raman spectra. The silver ions in the glass contributed to form stable (Al:Ag)O4 tetrahedra by pairing with aluminum ions and thus clustering of silver metal quantum dots was hindered.

  4. Mixed alkali effect in glasses containing MnO{sub 2}

    SciTech Connect

    Reddy, M. Sudhakara; Rajiv, Asha; Veeranna Gowda, V. C.; Chakradhar, R. P. S.; Reddy, C. Narayana

    2013-02-05

    Glass systems of the composition xLi{sub 2}O-(25-x)K{sub 2}O-70(0.4ZnO+0.6P{sub 2}O{sub 5})+5MnO{sub 2} (x = 4,8,12,16 and 20 mol %) have been prepared by melt quenching technique. The thermal and mechanical properties of the glasses have been evaluated as a function of mixed alkali content. Glass transition temperature and Vickers's hardness of the glasses show a pronounced deviation from linearity at 12 mol%Li{sub 2}O. Theoretically estimated elastic moduli of the glasses show small positive deviations from linearity. MAE in these properties has been attributed to the localized changes in the glass network. The absorption spectra of Mn{sup 2+} ions in these glasses showed strong broad absorption band at 514 nm corresponding to the transition {sup 6}A{sub 1g}(S){yields}{sup 4}T{sub 1g}(G), characteristic of manganese ions in octahedral symmetry. The fundamental absorption edge in UV region is used to study the optical transitions and electronic band structure. From UV absorption edge, optical band gap energies have been evaluated. Band gap energies of the glasses have exhibited MAE and shows minimum value for 12 mol%Li{sub 2}O glass.

  5. Alkali-free bioactive glasses for bone tissue engineering: A preliminary investigation

    SciTech Connect

    Goel, Ashutosh; Kapoor, Saurabh; Rajagopal, Raghu R.; Pascual, Maria J.; Kim, Hae-Won; Ferreira, Jose M.

    2011-08-25

    An alkali-free series of bioactive glasses has been designed and developed in the glass system CaO-MgO-SiO2-P2O5-CaF2 along diopside (CaMgSi2O6) – fluorapatite [Ca5(PO4)3F] – tricalcium phosphate (3CaO•P2O5) join. The silicate network in all the investigated glasses is predominantly coordinated in Q2 (Si) units while phosphorus tends to remain in orthophosphate (Q0) environment. The in vitro bioactivity analysis of glasses has been made by immersion of glass powders in simulated body fluid (SBF) while chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Some of the investigated glasses exhibit hydroxyapatite (HA) formation on their surface with in 1-12 h of their immersion in SBF solution. The sintering and crystallization kinetics of glasses has been investigated by differential thermal analysis (DTA) and hot-stage microscopy (HSM), respectively while the crystalline phase evolution in resultant glass-ceramics (GCs) has been studied in the temperature range of 800-900 oC using powder X-ray diffraction (XRD) and scanning electron microscope (SEM). The cell growth and osteogenic differentiation for glasses has been studied in vitro on sintered glass powder compacts using rat bone marrow mesenchymal stem cells. The as designed glasses are ideal candidates for their potential applications in bone tissue engineering in the form of bioactive glasses as well as glass/GC scaffolds.

  6. Monitoring ageing of alkali resistant glass fiber reinforced cement (GRC) using guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Eiras, J. N.; Amjad, U.; Mahmoudabadi, E.; Payá, J.; Bonilla, M.; Kundu, T.

    2013-04-01

    Glass fiber reinforced cement (GRC) is a Portland cement based composite with alkali resistant (AR) glass fibers. The main drawback of this material is the ageing of the reinforcing fibers with time and especially in presence of humidity in the environment. Until now only destructive methods have been used to evaluate the durability of GRC. In this study ultrasonic guided wave inspection of plate shaped specimens has been carried out. The results obtained here show that acoustic signatures are capable of discerning ageing in GRC. Therefore, the ultrasonic guided wave based inspection technique is a promising method for the nondestructive evaluation of the durability of the GRC.

  7. Coupled ion redistribution and electronic breakdown in low-alkali boroaluminosilicate glass

    SciTech Connect

    Choi, Doo Hyun; Randall, Clive Furman, Eugene Lanagan, Michael

    2015-08-28

    Dielectrics with high electrostatic energy storage must have exceptionally high dielectric breakdown strength at elevated temperatures. Another important consideration in designing a high performance dielectric is understanding the thickness and temperature dependence of breakdown strengths. Here, we develop a numerical model which assumes a coupled ionic redistribution and electronic breakdown is applied to predict the breakdown strength of low-alkali glass. The ionic charge transport of three likely charge carriers (Na{sup +}, H{sup +}/H{sub 3}O{sup +}, Ba{sup 2+}) was used to calculate the ionic depletion width in low-alkali boroaluminosilicate which can further be used for the breakdown modeling. This model predicts the breakdown strengths in the 10{sup 8}–10{sup 9 }V/m range and also accounts for the experimentally observed two distinct thickness dependent regions for breakdown. Moreover, the model successfully predicts the temperature dependent breakdown strength for low-alkali glass from room temperature up to 150 °C. This model showed that breakdown strengths were governed by minority charge carriers in the form of ionic transport (mostly sodium) in these glasses.

  8. Effect of alkaline-earth ions on the dynamics of alkali ions in bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Ghosh, A.

    2005-12-01

    The effect of alkaline earth ions on the dynamics of Li+ ions in bismuthate glasses has been studied in the temperature range 353-503K and in the frequency range 10Hz-2MHz . The dc conductivity increases and activation energy decreases with the increase of a particular alkaline earth content for the glasses with a fixed alkali content. The increased modification of the network due to the increase in alkaline earth content in the compositions is responsible for the increasing conductivity. Also the compositions with smaller alkaline earth ions were found to exhibit higher conductivity. Although the conductivity increases with the decrease of ionic radii of alkaline earth ions, the activation energy shows a maximum for the Sr ion. The electric modulus and the conductivity formalisms have been employed to study the relaxation dynamics of charge carriers in these glasses. The alkali ions were observed to change their dynamics with the change of the alkaline earth ions. The same anomalous trend for activation energy for the conductivity relaxation frequency and the hopping frequency was also observed for glasses containing SrO. It was also observed that the mobile lithium ion concentrations are independent of nature of alkaline earth ions in these glasses.

  9. Structural, dielectric and AC conductivity properties of Co2+ doped mixed alkali zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Madhu, B. J.; Banu, Syed Asma; Harshitha, G. A.; Shilpa, T. M.; Shruthi, B.

    2013-02-01

    The Co2+ doped 19.9ZnO+5Li2CO3+25Na2CO3+50B2O3 (ZLNB) mixed alkali zinc borate glasses have been prepared by a conventional melt quenching method. The structural (XRD & FT-IR), dielectric and a.c. conductivity (σac) properties have been investigated. Amorphous nature of these glasses has been confirmed from their XRD pattern. The dielectric properties and electrical conductivity (σac) of these glasses have been studied from 100Hz to 5MHz at the room temperature. Based on the observed trends in the a.c. conductivities, the present glass samples are found to exhibit a non-Debye behavior.

  10. Glass corrosion in natural environment

    NASA Technical Reports Server (NTRS)

    Thorpe, Arthur N.

    1989-01-01

    A series of studies of the effects of solutes which appear in natural aqueous environments, specifically Mg and Al, under controlled conditions, permit characterization of the retardation of silicate glass leaching in water containing such solutes. In the case of Mg the interaction with the glass appears to consist of exchange with alkali ions present in the glass to a depth of several microns. The effect of Al can be observed at much lower levels, indicating that the mechanism in the case of Al involves irreversible formation of aluminosilicate species at the glass surface.

  11. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    PubMed Central

    Cheng, Shaodong; Yang, Guang; Zhao, Yanqi; Peng, MingYing; Skibsted, Jørgen; Yue, Yuanzheng

    2015-01-01

    Transmission electron microscopy and related analytical techniques have been widely used to study the microstructure of different materials. However, few research works have been performed in the field of glasses, possibly due to the electron-beam irradiation damage. In this paper, we have developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which the fraction of BO4 tetrahedra can be obtained by fitting the experimental data with linear combinations of the reference spectra. The BO4 fractions (N4) obtained by EELS are consistent with those from 11B MAS NMR spectra, suggesting that EELS can be an alternative and convenient way to determine the N4 fraction in glasses. In addition, the boron speciation of a CeO2 doped potassium borosilicate glass has been analyzed by using the time-resolved EELS spectra. The results clearly demonstrate that the BO4 to BO3 transformation induced by the electron beam irradiation can be efficiently suppressed by doping CeO2 to the borosilicate glasses. PMID:26643370

  12. Luminescence spectra and structure of Er3+ doped alkali borate and fluoroborate glasses

    NASA Astrophysics Data System (ADS)

    Arul Rayappan, I.; Marimuthu, K.

    2013-11-01

    Trivalent erbium (Er3+) ion doped alkali borate and fluoroborate glasses were prepared and their structural and spectroscopic properties have been studied through XRD, FTIR, optical absorption and luminescence spectral measurements. The FTIR spectral studies reveal the presence of BO3, BO4 structural units and the strong OH- bonds in the title glasses. The absorption spectra were used to determine the bonding parameters (β¯,δ) of the prepared glasses. Judd—Ofelt intensity parameters (Ωλ, λ=2, 4 and 6) have been calculated from the optical absorption spectra and are used to predict the important radiative properties like radiative transition probability (A), stimulated emission cross-section (σPE) and branching ratios (βR) for the excited state transitions such as 2H9/2→4I15/2 and 4S3/2→4I15/2 of the Er3+ ions in the prepared glasses. Optical band gap energy (Eopt) values through direct, indirect allowed transitions and the Urbach energy (ΔE) values of the prepared Er3+ glasses have also been determined and compared with similar studies. The spectral characteristics of the Er3+ ions due to compositional changes have been examined and reported in the present work.

  13. Investigation of luminescence and spectroscopic properties of Nd3+ions in cadmium alkali borate glasses

    NASA Astrophysics Data System (ADS)

    Mohan, Shaweta; Thind, Kulwant Singh

    2016-07-01

    Neodymium doped cadmium alkali borate glasses having composition 20CdOsbnd 20R2Osbnd 59.5H3BO3sbnd 0.5Nd2O3; (R = Li, Na and K) were prepared by conventional melt-quenching technique. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical properties such as density, refractive index, molar volume, rare earth ion concentration etc. were determined. Optical absorption and fluorescence spectra were recorded. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. These parameters were in turn used to predict the radiative properties such as the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the fluorescent levels of Nd3+ ion in the present glass series. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. The variation of Ω2 with the change in alkali oxide has been attributed to the changes in the asymmetry of the ligand field at the rare earth ion site. The shift of the hypersensitive bands, study of the oscillator strengths and the variation of the spectral profile of the transition 4I9/2 → 4F7/2 + 4S3/2 indicate a maximum covalency of Ndsbnd O bond for glass with potassium ions. From the fluorescence spectra, peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) have been obtained for the three transitions 4F3/2 → 4I9/2,4F3/2 → 4I11/2 and4F3/2 → 4I13/2 of Nd3+ ion. The relatively high values of σp obtained for Nd3+ in present glass system suggest that these materials can be considered as suitable candidates for laser applications. The glass with potassium ions shows the highest value of the stimulated emission cross-section.

  14. Absorption and emission characteristics of Er3+ ions in alkali chloroborophosphate glasses.

    PubMed

    Moorthy, L R; Rao, T S; Janardhnam, K; Radhapathy, A

    2000-08-01

    Alkali chloroborophosphate glasses containing 1 mol% of Er3+ ions were studied experimentally using the absorption and emission spectroscopy. The energy level scheme for the 4f11 (Er3+) electronic configuration was deduced from the observed band energies of the absorption spectra in terms of a parametrized Hamiltonian using the various free-ion spectroscopic parameters. Oscillator strengths (f) measured from the absorption spectra have been analyzed using the Judd-Ofelt theory to evaluate the three intensity parameters omegalambda (lambda = 2, 4 and 6). Reasonable agreement between the measured and calculated f values has been found. Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were calculated for all the excited states of Er3+ ions. The non-radiative (WNR) relaxation rates from the excited levels to the next lower levels have been calculated and the relationship between the energy gap and non-radiative relaxation rate has been established. These results were used to predict the possible potential laser transitions in Er-doped alkali chloroborophosphate glasses.

  15. Optical properties of transparent cobalt-containing magnesium aluminosilicate glass-ceramics doped with gallium oxide for saturable absorbers

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Skoptsov, N. A.; Dymshits, O. S.; Malyarevich, A. M.; Yumashev, K. V.; Zhilin, A. A.; Alekseeva, I. P.

    2016-10-01

    Transparent glass-ceramic materials based on glasses of the MgO-Al2O3-SiO2-TiO2 system doped with CoO and Ga2O3 are synthesized. The secondary heat treatment of the initial glasses at temperatures of 800-950°C leads to precipitation of nanosized (6-7 nm) crystals of magnesium aluminogallium spinel doped with cobalt ions and magnesium aluminotitanate solid solutions. The optical absorption spectra of the initial glass and glass-ceramic materials are studied. It is shown that the absorption band caused by the 4 A 2(4F)→ 4 T 1(4 F) transitions of tetrahedrally coordinated Co2+ ions in glass-ceramics with nanosized Co:Mg(Al,Ga)2O4 crystals is shifted to longer wavelengths (up to 1.67 µm) compared to the position of this band in materials with Co:MgAl2O4 crystals. The synthesized glass-ceramics are characterized by a relatively low saturation fluence FS 0.5 ± 0.1 J/cm2 at a wavelength of 1.54 µm, as well as by a high radiation resistance to nanosecond laser pulses, which is no lower than 15 ± 2 J/cm2. This explains their attractiveness as materials for saturable absorbers for erbium lasers emitting in the spectral range 1.5-1.7 µm.

  16. Compliant alkali silicate sealing glass for solid oxide fuel cell applications: thermal cycle stability and chemical compatibility

    SciTech Connect

    Chou, Y. S.; Thomsen, Edwin C.; Williams, Riley T.; Choi, Jung-Pyung; Canfield, Nathan L.; Bonnett, Jeff F.; Stevenson, Jeffry W.; Shyam, Amit; Lara-Curzio, E.

    2011-03-01

    An alkali silicate glass (SCN-1) is currently being evaluated as a candidate sealing glass for solid oxide fuel (SOFC) applications. The glass containing ~17 mole% alkalis (K2O and Na2O) remains vitreous and compliant during SOFC operation, unlike conventional SOFC sealing glasses, which experience substantial devitrification after the sealing process. The non-crystallizing compliant sealing glass has lower glass transition and softening temperatures since the microstructure remains glassy without significant crystallite formation, and hence can relieve or reduce residual stresses and also has the potential for crack healing. Sealing approaches based on compliant glass will also need to satisfy all the mechanical, thermal, chemical, physical, and electrical requirements for SOFC applications, not only in bulk properties but also at sealing interfaces. In this first of a series of papers we will report the thermal cycle stability of the glass when sealed between two SOFC components, i.e., a NiO/YSZ anode supported YSZ bilayer and a coated ferritic stainless steel interconnect material. High temperature leak rates were monitored versus thermal cycles between 700-850oC using back pressures ranging from 0.2 psi to 1.0 psi. Isothermal stability was also evaluated in a dual environment consisting of flowing dilute H2 fuel versus ambient air. In addition, chemical compatibility at the alumina and YSZ interfaces was examined with scanning electron microscopy and energy dispersive spectroscopy. The results shed new light on the topic of SOFC glass seal development.

  17. Studies on the preparation and plasma spherodization of yttrium aluminosilicate glass microspheres for their potential application in liver brachytherapy

    NASA Astrophysics Data System (ADS)

    Sreekumar, K. P.; Saxena, S. K.; Kumar, Yogendra; Thiyagarajan, T. K.; Dash, Ashutosh; Ananthapadmanabhan, P. V.; Venkatesh, Meera

    2010-02-01

    Plasma spheroidization exploits the high temperature and high enthalpy available in the thermal plasma jet to melt irregularly shaped powder particles and quench them to get dense spherical particles. Plasma spheroidization is a versatile process and can be applied to metals, ceramics, alloys and composites to obtain fine spherical powders. Radioactive microspheres incorporated with high energetic beta emitting radioisotopes have been reported to be useful in the palliative treatment of liver cancer. These powders are to be prepared in closer range of near spherical morphology in the size range 20-35 microns. Inactive glass samples were prepared by heating the pre-calculated amount of glass forming ingredients in a recrystallized alumina crucible. The glass was formed by keeping the glass forming ingredients at 1700°C for a period of three hours to form a homogeneous melt. After cooling, the glass was recovered from the crucible by crushing and was subsequently powdered mechanically with the help of mortar and pestle. This powder was used as the feed stock for plasma spheroidization using an indigenously developed 40 kW plasma spray system. Experiments were carried out at various operating parameters. The operating parameters were optimised to get spheroidised particles. The powder was sieved to get the required size range before irradiation.

  18. Effects of Fiber Content on Mechanical Properties of CVD SiC Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1996-01-01

    Unidirectional CVD SiC(f)(SCS-6) fiber-reinforced strontium aluminosilicate (SAS) glass-ceramic matrix composites containing various volume fractions, approximately 16 to 40 volume %, of fibers were fabricated by hot pressing at 1400 C for 2 h under 27.6 MPa. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase formed, with complete absence of the undesired hexacelsian phase, in the matrix. Room temperature mechanical properties were measured in 3-point flexure. The matrix microcracking stress and the ultimate strength increased with increase in fiber volume fraction, reached maximum values for V(sub f) approximately equal to 0.35, and degraded at higher fiber loadings. This degradation in mechanical properties is related to the change in failure mode, from tensile at lower V(sub f) to interlaminar shear at higher fiber contents. The extent of fiber loading did not have noticeable effect on either fiber-matrix debonding stress, or frictional sliding stress at the interface. The applicability of micromechanical models in predicting the mechanical properties of the composites was also examined. The currently available theoretical models do not appear to be useful in predicting the values of the first matrix cracking stress, and the ultimate strength of the SCS-6/SAS composites.

  19. Physical, structural and spectroscopic investigations of Sm3+ doped ZnO mixed alkali borate glass

    NASA Astrophysics Data System (ADS)

    Sailaja, B.; Joyce Stella, R.; Thirumala Rao, G.; Jaya Raja, B.; Pushpa Manjari, V.; Ravikumar, R. V. S. S. N.

    2015-09-01

    Glass of 20ZnO-15 Li2O-15 Na2O-49.9 B2O3 doped with 0.1 mol% of Sm3+ (ZLNB) was prepared by the melt quenching technique. Physical properties were studied and analysed. The XRD studies confirm the amorphous nature of sample. The FT-IR spectral investigation discloses the BO3, BO4 groups, H and OH bonds. Optical absorption and emission spectra were recorded and characterized. Judd-Ofelt theory was applied to f ↔ f transitions to evaluate Judd-Ofelt intensity parameters (Ωλ). The oscillator strengths and bonding parameters were determined from absorption spectra. The trend observed was Ω4 > Ω6 > Ω2. High value of Ω4 reveals higher rigidity and covalency around the Sm3+ ion. Low value of Ω2 implies ionic nature of ligands and site symmetry around Sm3+ ion. luminescence data and Judd-Ofelt parameters Ωλ (λ = 2, 4, and 6) were used to evaluate various radiative probabilities like spontaneous radiative emission probabilities (AR), radiative lifetime (τR) and branching ratios (βR) stimulated emission cross section (σe) and CIE colour coordinates were measured, CCT temperature evaluated and the values were used to ascertain potential laser transitions at the optimum mixed alkali effect observed for the glass sample prepared. The preparedness of the material as the efficient laser active material is examined.

  20. Effect of Al concentration on the holographic grating efficiency and ionic conductivity in sodium magnesium aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    Hamad, Abdulatif Y.; Wicksted, James P.; Hogsed, Michael R.; Martin, Joel J.; Hunt, Charles A.; Dixon, George S.

    2002-02-01

    A systematic study of grating formation, erasure, and decay in 15Na2O.12MgO.xAl2O3.(73-x)SiO2 glasses doped with 1.26 mol% Eu2O3 is reported as a function of Al2O3 concentration for x=0 to 15. The permanent change in the index of refraction was a linearly increasing function of Al2O3 concentration. The grating buildup and erasure rates also increased with Al2O3 concentrations. This is attributed to the reduced activation energy for forced diffusion of small modifiers bound to AlO-4 clusters rather than to nonbridging oxygens. Ionic conductivities were also measured to confirm the reduction of the activation energies. The results of this study support the model for grating kinetics in rare-earth sensitized glasses proposed recently by Dixon, Hamad, and Wicksted.

  1. Environmental effects on initiation and propagation of surface defects on silicate glasses: scratch and fracture toughness study

    NASA Astrophysics Data System (ADS)

    Surdyka, Nicholas D.; Pantano, Carlo G.; Kim, Seong H.

    2014-08-01

    The glass composition and surrounding environment can play an important role in the initiation and propagation of surface defects, which affect the practical strength of glass. We have studied how the environment and glass composition affect the tribological and indentation properties of multicomponent silicate glasses. Soda lime silica and aluminosilicate glasses were studied to compare the effects of the alkali ion and glass network type on surface defect formation. Although both glasses contained leachable sodium ions, the surface wear of soda lime glass decreased with increasing humidity while sodium aluminosilicate glass had an observable increase in surface wear. This indicated that sodium ion and water activity on/in glass surfaces vary depending on the glass network structure. The exchange of Na+ with K+ in aluminosilicate glass increased the elastic modulus, hardness, and resistance to fracture substantially; however, it did not improve the surface scratch resistance in humid environments. This suggested that the improved fracture toughness for the K-exchanged aluminosilicate glass is mainly due to the improved bulk properties; surface wear can readily take place regardless of Na/K-exchange.

  2. Chemical Vapor Deposited SiC (SCS-0) Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1997-01-01

    Unidirectional SrO Al2O3 2SiO2 glass-ceramic matrix composites reinforced with uncoated Chemical Vapor Deposited (CVD) SiC (SCS-0) fibers have been fabricated by hot-pressing under appropriate conditions using the glass-ceramic approach. Almost fully dense composites having a fiber volume fraction of 0.24 have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix by x-ray diffraction. No chemical reaction was observed between the fiber and the matrix after high temperature processing. In three-point flexure, the composite exhibited a first matrix cracking stress of approx. 231 +/- 20 MPa and an ultimate strength of 265 +/- 17 MPa. Examination of fracture surfaces revealed limited short length fiber pull-out. From fiber push-out, the fiber/matrix interfacial debonding and frictional strengths were evaluated to be approx. 17.5 +/- 2.7 MPa and 11.3 +/- 1.6 MPa, respectively. Some fibers were strongly bonded to the matrix and could not be pushed out. The micromechanical models were not useful in predicting values of the first matrix cracking stress as well as the ultimate strength of the composites.

  3. High thermal neutron flux effects on structural and macroscopic properties of alkali-borosilicate glasses used as neutron guide substrate

    NASA Astrophysics Data System (ADS)

    Boffy, R.; Peuget, S.; Schweins, R.; Beaucour, J.; Bermejo, F. J.

    2016-05-01

    The behaviour of four alkali-borosilicate glasses under homogeneous thermal neutron irradiation has been studied. These materials are used for the manufacturing of neutron guides which are installed in most facilities as devices to transport neutrons from intense sources such as nuclear reactors or spallation sources up to scientific instruments. Several experimental techniques such as Raman, NMR, SANS and STEM have been employed in order to understand the rather different macroscopic behaviour under irradiation of materials that belong to a same glass family. The results have shown that the remarkable glass shrinking observed for neutron doses below 0.5 ·1018 n/cm2 critically depends upon the presence of domains where silicate and borate network do not mix.

  4. Influence of gallium and alkali halide addition on the optical and thermo mechanical properties of GeSe2-Ga2Se3 glass

    NASA Astrophysics Data System (ADS)

    Volk, Y. V.; Malyarevich, A. M.; Yumashev, K. V.; Matrosov, V. N.; Matrosova, T. A.; Kupchenko, M. I.

    2007-10-01

    A systematic compositional study of a new family of chalcogenide glasses, transparent from the visible range up to 16 μm has been performed. Numerous glass forming regions were explored in the GeSe2-Ga2Se3-MX system (MX = alkali halide) in order to understand the role of alkali halides and the effect of Ga substitution for Sb in the glass structure. To that avail, several ternary diagrams were investigated, and optical and thermo-mechanical measurements were performed. It is shown that the introduction of an alkali halide in the GeSe2-Ga2Se3 glasses increased the band-gap energy Eg by stabilizing electrons from the lone pairs of selenium. However, the glass hardness was lowered due to a decrease in the glass network reticulation. The chemical resistance was studied in a glass containing high CsCl content. Significant corrosion occurred when the glass was exposed to hot water for several hours. There is a great deal of interest in these glasses for use in thermal imaging devices, as they permit the alignment of infrared optical systems with visible red light. Furthermore, the low cost of raw materials and the possibility of shaping these glasses into lenses by molding could extend their utilization from defense to civilian applications.

  5. Influence of gallium and alkali halide addition on the optical and thermo-mechanical properties of GeSe2-Ga2Se3 glass

    NASA Astrophysics Data System (ADS)

    Calvez, L.; Lucas, P.; Rozé, M.; Ma, H. L.; Lucas, J.; Zhang, X. H.

    2007-10-01

    A systematic compositional study of a new family of chalcogenide glasses, transparent from the visible range up to 16 μm has been performed. Numerous glass forming regions were explored in the GeSe2-Ga2Se3-MX system (MX = alkali halide) in order to understand the role of alkali halides and the effect of Ga substitution for Sb in the glass structure. To that avail, several ternary diagrams were investigated, and optical and thermo-mechanical measurements were performed. It is shown that the introduction of an alkali halide in the GeSe2-Ga2Se3 glasses increased the band-gap energy Eg by stabilizing electrons from the lone pairs of selenium. However, the glass hardness was lowered due to a decrease in the glass network reticulation. The chemical resistance was studied in a glass containing high CsCl content. Significant corrosion occurred when the glass was exposed to hot water for several hours. There is a great deal of interest in these glasses for use in thermal imaging devices, as they permit the alignment of infrared optical systems with visible red light. Furthermore, the low cost of raw materials and the possibility of shaping these glasses into lenses by molding could extend their utilization from defense to civilian applications.

  6. Identifying glass compositions in fly ash

    NASA Astrophysics Data System (ADS)

    Aughenbaugh, Katherine; Stutzman, Paul; Juenger, Maria

    2016-01-01

    In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

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

    PubMed

    Sato, K; Hatta, T

    2015-03-07

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

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

    NASA Astrophysics Data System (ADS)

    Sato, K.; Hatta, T.

    2015-03-01

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

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

    SciTech Connect

    Sato, K.; Hatta, T.

    2015-03-07

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

  10. Optical parameters and upconversion fluorescence in Tm3+/Yb3+-doped alkali-barium-bismuth-tellurite glasses.

    PubMed

    Lin, Hai; Liu, Ke; Lin, Lin; Hou, Yanyan; Yang, Dianlai; Ma, Tiecheng; Pun, Edwin Yun Bun; An, Qingda; Yu, Jiayou; Tanabe, Setsuhisa

    2006-11-01

    Tm(3+)/Yb(3+)-doped alkali-barium-bismuth-tellurite (LKBBT) glasses have been fabricated and characterized. Density, refractive index, optical absorption, absorption and emission cross-sections of Yb(3+), Judd-Ofelt parameters and spontaneous transition probabilities of Tm(3+) have been measured and calculated, respectively. Intense blue three-photon upconversion fluorescence and near-infrared two-photon upconversion fluorescence were investigated under the excitation of a 980 nm diode laser at room temperature. Wide infrared transmission window, high refractive index and strong blue three-photon upconversion emission of Tm(3+) indicate that Tm(3+)/Yb(3+) co-doped LKBBT glasses are promising upconversion optical and laser materials.

  11. Dy3+ ions doped single and mixed alkali fluoro tungsten tellurite glasses for LASER and white LED applications

    NASA Astrophysics Data System (ADS)

    Annapurna Devi, Ch. B.; Mahamuda, Sk.; Venkateswarlu, M.; Swapna, K.; Srinivasa Rao, A.; Vijaya Prakash, G.

    2016-12-01

    A new-fangled series of Dy3+ ions doped Single and Mixed Alkali Fluoro Tungsten Tellurite Glasses have been prepared by using melt quenching technique and their spectroscopic behaviour was investigated by using XRD, optical absorption, photoluminescence and lifetime measurements. The bonding parameter studies reveal the ionic nature of the Dysbnd O bond in the present glasses. From the absorption spectra, the Judd-Ofelt (J-O) intensity parameters have been determined and in turn used to determine various radiative properties for the different emission transitions from the 4F9/2 fluorescent level. The photoluminescence spectra of all the glasses exhibit two intensified peaks in blue and yellow regions corresponding to the transitions 4F9/2 → 6H15/2 (483 nm) and 4F9/2 → 6H13/2 (575 nm) respectively. From the photoluminescence spectra, it is observed that the luminescence intensity is maximum for Dy3+ ion doped potassium combination of tungsten tellurite glass (TeWK:1Dy). The highest emission cross-section and branching ratio values observed for the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions suggest the possible laser action in the visible region from these glasses. By correlating the experimental lifetimes (τexp) measured from the decay spectral features with radiative lifetimes (τR), the quantum efficiencies (η) for all the glasses have been evaluated and found to be maximum for potassium combination tungsten tellurite (TeWK:1Dy) glass. The CIE colour chromaticity coordinates (x, y), (u, v), colour correlated temperature (CCT) and Y/B ratio were also estimated from the photoluminescence spectra for different compositions of glasses. The chromaticity colour coordinates evaluated for all the glasses fall within the white light region and white light emission can be tuned by varying the composition of the glass. From all these studies, it was concluded that 1 mol% of Dy3+ ions doped TeWK glass is more suitable for lasing and white-LED applications.

  12. Microprobes aluminosilicate ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Methods have been developed to make mixed alumina-silicate and aluminosilicate particulate microporous ceramic membranes. One method involves the making of separate alumina and silica sols which are then mixed. Another method involves the creation of a combined sol with aluminosilicate particles. The resulting combined alumina and silica membranes have high surface area, a very small pore size, and a very good temperature stability.

  13. DEVELOPMENT OF GLASS COMPOSITIONS TO IMMOBILIZE ALKALI, ALKALINE EARTH, LANTHANIDE AND TRANSITION METAL FISSION PRODUCTS FROM NUCLEAR FUEL REPROCESSING

    SciTech Connect

    Marra, J.; Billings, A.

    2009-06-24

    The Advanced Fuel Cycle Initiative (AFCI) waste management strategy revolves around specific treatment of individual or groups of separated waste streams. A goal for the separations processes is to efficiently manage the waste to be dispositioned as high level radioactive waste. The Advanced Fuel Cycle Initiative (AFCI) baseline technology for immobilization of the lanthanide (Ln) and transition metal fission product (TM) wastes is vitrification into a borosilicate glass. A current interest is to evaluate the feasibility of vitrifying combined waste streams to most cost effectively immobilize the wastes resulting from aqueous fuel reprocessing. Studies showed that high waste loadings are achievable for the Ln only (Option 1) stream. Waste loadings in excess of 60 wt % (on a calcined oxide basis) were demonstrated via a lanthanide borosilicate (LaBS) glass. The resulting glasses had excellent relative durability as determined by the Product Consistency Test (PCT). For a combined Ln and TM waste stream glass (Option 2), noble metal solubility was found to limit waste loading. However, the measured PCT normalized elemental releases for this glass were at least an order of magnitude below that of Environmental Assessment (EA) glass. Current efforts to evaluate the feasibility of vitrifying combined Ln, TM, alkali (Cs is the primary radionuclide of concern) and alkaline earth (Sr is the primary radionuclide of concern) wastes (Option 3) have shown that these approaches are feasible. However, waste loading limitations with respect to heat load (Cs/Sr loading), molybdenum solubility and/or noble metal solubility will likely be realized and must be considered in determining the cost effectiveness of these approaches.

  14. Compliant alkali silicate sealing glass for solid oxide fuel cell applications: the effect of protective alumina coating on electrical stability in dual environment

    SciTech Connect

    Chou, Y. S.; Choi, Jung-Pyung; Stevenson, Jeffry W.

    2012-12-01

    An alkali-containing silicate glass was recently proposed as a potential sealant for solid oxide fuel cells (SOFC). The glass contains appreciable amount of alkalis and retains its glassy microstructure at elevated temperatures over time. It is more compliant as compared to conventional glass-ceramics sealants and could potentially heal cracks during thermal cycling. In previous papers the thermal cycle stability, thermal stability and chemical compatibility were reported with yttria-stabilized zirconia (YSZ) electrolyte and YSZ-coated ferritic stainless steel interconnect. In this paper, we report the electrical stability of the compliant glass with aluminized AISI441 interconnect material under DC load in dual environment at 700-800oC. Apparent electrical resistivity was measured with a 4-point method for the glass sealed between two aluminized AISI441 metal coupons as well as plain AISI441 substrates. The results showed good electrical stability with the aluminized AISI441 substrate, while unstable behavior was observed for un-coated substrates. In addition, interfacial microstructure was examined with scanning electron microscopy and correlated with the measured resistivity results. Overall, the alumina coating demonstrated good chemical stability with the alkali-containing silicate sealing glass under DC loading.

  15. Structure of Alkali Borate Glasses at High Pressure: B and Li K-Edge Inelastic X-Ray Scattering Study

    SciTech Connect

    Lee, Sung Keun; Eng, Peter J.; Mao, Ho-kwang; Meng, Yue; Shu, Jinfu

    2008-06-16

    We report the first in situ boron K-edge inelastic x-ray scattering (IXS) spectra for alkali borate glasses (Li{sub 2}B{sub 4}O{sub 7}) at high pressure up to 30 GPa where pressure-induced coordination transformation from three-coordinated to four-coordinated boron was directly probed. Coordination transformation (reversible upon decompression) begins around 5 GPa and the fraction of four-coordinated boron increases with pressure from about 50% (at 1 atm) to more than 95% (at 30 GPa) with multiple densification mechanisms, evidenced by three distinct pressure ranges for (d{sup [4]}B/dP){sub T}. The lithium K-edge IXS spectrum for Li-borate glasses at 5 GPa shows IXS features similar to that at 1 atm, suggesting that the Li environment does not change much with pressure up to 5 GPa. These results provide improved understanding of the structure of low-z glass at high pressure.

  16. Investigation of emulsified, acid and acid-alkali catalyzed mesoporous bioactive glass microspheres for bone regeneration and drug delivery.

    PubMed

    Miao, Guohou; Chen, Xiaofeng; Dong, Hua; Fang, Liming; Mao, Cong; Li, Yuli; Li, Zhengmao; Hu, Qing

    2013-10-01

    Acid-catalyzed mesoporous bioactive glass microspheres (MBGMs-A) and acid-alkali co-catalyzed mesoporous bioactive glass microspheres (MBGMs-B) were successfully synthesized via combination of sol-gel and water-in-oil (W/O) micro-emulsion methods. The structural, morphological and textural properties of mesoporous bioactive glass microspheres (MBGMs) were characterized by various techniques. Results show that both MBGMs-A and MBGMs-B exhibit regularly spherical shape but with different internal porous structures, i.e., a dense microstructure for MBGMs-A and internally porous structure for MBGMs-B. (29)Si NMR data reveal that MGBMs have low polymerization degree of silica network. The in vitro bioactivity tests indicate that the apatite formation rate of MBGMs-B was faster than that of MBGMs-A after soaking in simulated body fluid (SBF) solution. Furthermore, the two kinds of MBGMs have similar storage capacity of alendronate (AL), and the release behaviors of AL could be controlled due to their unique porous structure. In conclusion, the microspheres are shown to be promising candidates as bone-related drug carriers and filling materials of composite scaffold for bone repair.

  17. Study of bi-alkali photocathode growth on glass by X-ray techniques for fast timing response photomultipliers

    NASA Astrophysics Data System (ADS)

    Xie, Junqi; Demarteau, Marcel; Wagner, Robert; Ruiz-Oses, Miguel; Liang, Xue; Ben-Zvi, Ilan; Attenkofer, Klaus; Schubert, Susanne; Smedley, John; Wong, Jared; Padmore, Howard; Woll, Arthur

    2014-03-01

    Bi-alkali antimonide photocathode is an essential component in fast timing response photomultipliers. Real-time in-situ grazing incidence x-ray diffraction and post-growth x-ray reflectivity measurement were performed to study the photocathode deposition process on glass substrate. Grazing incidence x-ray diffraction patterns show the formation of Sb crystalline, dissolution of crystalline phase Sb by the application of K vapor and reformation of refined crystal textures. XRR result exhibits that the film thickness increases ~ 4.5 times after K diffusion and almost have no change after Cs diffusion. Further investigation is expected to understand the photocathode growth process and provide guidelines for photocathode development.

  18. Multilevel tunnelling systems and fractal clustering in the low-temperature mixed alkali-silicate glasses.

    PubMed

    Jug, Giancarlo; Paliienko, Maksym

    2013-01-01

    The thermal and dielectric anomalies of window-type glasses at low temperatures (T < 1 K) are rather successfully explained by the two-level systems (2LS) standard tunneling model (STM). However, the magnetic effects discovered in the multisilicate glasses in recent times, magnetic effects in the organic glasses, and also some older data from mixed (SiO₂)(1-x) (K₂O)(x) and (SiO₂)(1-x) (Na₂O)(x) glasses indicate the need for a suitable extension of the 2LS-STM. We show that--not only for the magnetic effects, but also for the mixed glasses in the absence of a field--the right extension of the 2LS-STM is provided by the (anomalous) multilevel tunnelling systems (ATS) proposed by one of us for multicomponent amorphous solids. Though a secondary type of TS, different from the standard 2LS, was invoked long ago already, we clarify their physical origin and mathematical description and show that their contribution considerably improves the agreement with the experimental data. In spite of dealing with low-temperature properties, our work impinges on the structure and statistical physics of glasses at all temperatures.

  19. Structural investigation and electron paramagnetic resonance of vanadyl doped alkali niobium borate glasses.

    PubMed

    Agarwal, A; Sheoran, A; Sanghi, S; Bhatnagar, V; Gupta, S K; Arora, M

    2010-03-01

    Glasses with compositions xNb(2)O(5).(30-x)M(2)O.69B(2)O(3) (where M=Li, Na, K; x=0, 4, 8 mol%) doped with 1 mol% V(2)O(5) have been prepared using normal melt quench technique. The IR transmission spectra of the glasses have been studied over the range 400-4000 cm(-1). The changes caused by the addition of Nb(2)O(5) on the structure of these glasses have been reported. The electron paramagnetic resonance spectra of VO(2+) ions in these glasses have been recorded in X-band (9.14 GHz) at room temperature (300 K). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that the resultant resonance spectra contain hyperfine structures (hfs) due to V(4+) ions which exist as VO(2+) ions in octahedral coordination with a tetragonal compression in the present glasses. The tetragonality of V(4+)O(6) complex decreases with increasing concentration of Nb(2)O(5). The 3d(xy) orbit contracts with increase in Nb(2)O(5):M(2)O ratio. Values of the theoretical optical basicity, Lambda(th), have also been reported.

  20. Spectroscopic characterization of alkali modified zinc-tellurite glasses doped with neodymium.

    PubMed

    Rajeswari, R; Babu, S Surendra; Jayasankar, C K

    2010-09-15

    Neodymium doped zinc-tellurite glasses of composition TeO(2)-ZnO-Na(2)O-Li(2)O have been prepared and characterized for their thermal, structural and optical properties. Differential thermal analysis revealed reasonably good forming tendency of the glass composition. FTIR spectra were used to analyze the functional groups present in the glass. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime, branching ratio and stimulated emission cross-section for (4)F(3/2)-->(4)I(9/2, 11/2, 13/2) transitions. The quantum efficiency of the (4)F(3/2) level is comparable to the typical values obtained for the Nd(2)O(3)-doped glasses. The decay properties for higher concentration of Nd(2)O(3) were analyzed using Inokuti-Hirayama model to investigate the non-radiative relaxation of the (4)F(3/2) emitting level. The experimental values of branching ratio and saturation intensity of (4)F(3/2)-->(4)I(11/2) transition and calculated spectroscopic quality factor indicate the favourable lasing action in these glasses.

  1. Silicate species of water glass and insights for alkali-activated green cement

    SciTech Connect

    Jansson, Helén; Bernin, Diana; Ramser, Kerstin

    2015-06-15

    Despite that sodium silicate solutions of high pH are commonly used in industrial applications, most investigations are focused on low to medium values of pH. Therefore we have investigated such solutions in a broad modulus range and up to high pH values (∼14) by use of infrared (IR) spectroscopy and silicon nuclear magnetic resonance ({sup 29}Si-NMR). The results show that the modulus dependent pH value leads to more or less charged species, which affects the configurations of the silicate units. This in turn, influences the alkali-activation process of low CO{sub 2} footprint cements, i.e. materials based on industrial waste or by-products.

  2. Dependence of the mixed alkali effect on temperature and total alkali oxide content in y[xLi{sub 2}O.(1-x)Na{sub 2}O].(1-y)B{sub 2}O{sub 3} glasses

    SciTech Connect

    Gao Yong . E-mail: yonggao@uni-muenster.de

    2005-11-15

    The complex conductivity spectra of mixed alkali borate glasses of compositions y [xLi{sub 2}O.(1-x)Na{sub 2}O].(1-y)B{sub 2}O{sub 3} (with x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0; y=0.1, 0.2, 0.3) in a frequency range between 10{sup -2}Hz and 3MHz and at temperatures ranging from 298 to 573K have been studied. For each glass composition the conductivities show a transition from the dc values into a dispersive regime where the conductivity is found to increase continuously with frequency, tending towards a linear frequency dependence at sufficiently low temperatures. Mixed alkali effects (MAEs) in the dc conductivity and activation energy are identified and discussed. It has been for the first time found that the strength of the MAE in the logarithm of the dc conductivity linearly increases with the total alkali oxide content, y, and the reciprocal temperature, 1/T.

  3. Chemical constraints on fly ash glass compositions

    SciTech Connect

    John H. Brindle; Michael J. McCarthy

    2006-12-15

    The major oxide content and mineralogy of 75 European fly ashes were examined, and the major element composition of the glass phase was obtained for each. Correlation of compositional trends with the glass content of the ash was explored. Alkali content was deduced to have a major influence on glass formation, and this in turn could be related to the probable chemistry of clay minerals in the source coals. Maximal glass content corresponded to high aluminum content in the glass, and this is in accordance with the theoretical mechanism of formation of aluminosilicate glasses, in which network-modifying oxides are required to promote tetrahedral coordination of aluminum in glass chain structures. Iron oxide was found to substitute for alkali oxides where the latter were deficient, and some indications of preferred eutectic compositions were found. The work suggests that the proportion of the glass phase in the ash can be predicted from the coal mineralogy and that the utility of a given ash for processing into geopolymers or zeolites is determined by its source. 23 refs., 7 figs., 1 tab.

  4. Entropy and structure of silicate glasses and melts

    USGS Publications Warehouse

    Richet, P.; Robie, R.A.; Hemingway, B.S.

    1993-01-01

    Low-temperature adiabatic Cp measurements have been made on NaAlSi2O6, MgSiO3, Ca3Al2Si3O12 and Ca1.5Mg1.5Al2Si3O12 glasses. Above about 50 K, these and previous data show that the heat capacity is an additive function of composition to within ??1% throughout the investigated glassforming part of the system CaO-MgO-Al2O3-SiO2. In view of the determining role of oxygen coordination polyhedra on the low-temperature entropy, this is interpreted as indicating that Si and Al are tetrahedrally coordinated in all these glasses, in agreement with structural data; whereas Ca and Mg remain octahedrally coordinated. In contrast, heat capacities and entropies are not additive functions of composition for alkali aluminosilicates, indicating increases in the coordination numbers of alkali elements from about six to nine when alumina is introduced. A thermochemical consequence of additivity of vibrational entropies of glasses is that entropies of mixing are essentially configurational for calcium and magnesium aluminosilicate melts. For alkali-bearing liquids, it is probable that vibrational entropies contribute significantly to entropies of mixing. At very low temperatures, the additive nature of the heat capacity with composition is less well followed, likely as a result of specific differences in medium-range order. ?? 1993.

  5. Hot isostatically-pressed aluminosilicate glass-ceramic with natural crystalline analogues for immobilizing the calcined high-level nuclear waste at the Idaho Chemical Processing Plant

    SciTech Connect

    Raman, S.

    1993-12-01

    The additives Si, Al, MgO, P{sub 2}O{sub 5} were mechanically blended with fluorinelsodium calcine in varying proportions. The batches were vacuum sealed in stainless steel canisters and hot isostatically pressed at 20,000 PSI and 1000 C for 4 hours. The resulting suite of glass-ceramic waste forms parallels the natural rocks in microstructural and compositional heterogeneity. Several crystalline phases ar analogous in composition and structure to naturally occurring minerals. Additional crystalline phases are zirconia and Ca-Mg borate. The glasses are enriched in silica and alumina. Approximately 7% calcine elements occur dissolved in this glass and the total glass content in the waste forms averages 20 wt%. The remainder of the calcine elements are partitioned into crystalline phases at 75 wt% calcine waste loading. The waste forms were tested for chemical durability in accordance with the MCC1-test procedure. The leach rates are a function of the relative proportions of additives and calcine, which in turn influence the composition and abundances of the glass and crystalline phases. The DOE leach rate criterion of less than 1 g/m{sup 2}-day is met by all the elements B, Cs and Na are increased by lowering the melt viscosity. This is related to increased crystallization or devitrification with increases in MgO addition. This exploratory work has shown that the increases in waste loading occur by preferred partitioning of the calcine components among crystalline and glass phases. The determination of optimum processing parameters in the form of additive concentration levels, homogeneous blending among the components, and pressure-temperature stabilities of phases must be continued to eliminate undesirable effects of chemical composition, microstructure and glass devitrification.

  6. Compliant alkali silicate sealing glass for solid oxide fuel cell applications: the effect of protective YSZ coating on electrical stability in dual environment

    SciTech Connect

    Chou, Y. S.; Thomsen, Edwin C.; Choi, Jung-Pyung; Stevenson, Jeffry W.

    2012-03-15

    Recently, compliant sealing glass has been proposed as a potential candidate sealant for solid oxide fuel cell (SOFC) applications. In a previous paper, the thermal stability and chemical compatibility were reported for a compliant alkali-containing silicate glass sealed between anode supported YSZ bi-layer and YSZ-coated stainless steel interconnect. In this paper, we will report the electrical stability of the compliant glass under a DC load and dual environment at 700-800 degrees C. Apparent electrical resistivity was measured with a 4-point method for the glass sealed between two plain SS441 metal coupons or YSZ-coated aluminized substrates. The results showed instability with plain SS441 at 800 degrees C, but stable behavior of increasing resistivity with time was observed with the YSZ coated SS441. In addition, results of interfacial microstructure analysis with scanning electron microscopy will be correlated with the measured resistivity results. Overall, the YSZ coating demonstrated chemically stability with the alkali-containing compliant silicate sealing glass under electrical field and dual environments.

  7. Optical properties and frequency upconversion fluorescence in a Tm3+ -doped alkali niobium tellurite glass

    NASA Astrophysics Data System (ADS)

    Poirier, Gadiaere; L.; Cassanjes, Fabia C.; de Araújo, Cid B.; Jerez, Vladimir A.; Ribeiro, Sidney J. L.; Messaddeq, Younes; Poulain, Marcel

    2003-03-01

    Optical spectroscopic properties of Tm3+-doped 60TeO2-10GeO2-10K2O-10Li2O-10Nb2O5 glass are reported. The absorption spectra were obtained and radiative parameters were determined using the Judd-Ofelt theory. Characteristics of excited states were studied in two sets of experiments. Excitation at 360 nm originates a relatively narrow band emission at 450 nm attributed to transition 1D2→3F4 of the Tm3+ ion with photon energy larger than the band-gap energy of the glass matrix. Excitation at 655 nm originates a frequency upconverted emission at 450 nm (1D2→3F4) and emission at 790 nm (3H4→3H6). The radiative lifetimes of levels 1D2 and 3H4 were measured and the differences between their experimental values and the theoretical predictions are understood as due to the contribution of energy transfer among Tm3+ ions.

  8. The in vivo performance of an alkali-free bioactive glass for bone grafting, FastOs(®) BG, assessed with an ovine model.

    PubMed

    Cortez, Paulo P; Brito, Ana F; Kapoor, Saurabh; Correia, Ana F; Atayde, Luis M; Dias-Pereira, Patrícia; Maurício, Ana Colette; Afonso, Américo; Goel, Ashutosh; Ferreira, José M F

    2017-01-01

    Although bioactive glasses are successfully used as bone substitutes, recent studies have revealed that the high alkali content in these glasses leads to fast in vivo degradation rates that may not match the rate of new bone ingrowth. This prompted us to design and develop novel bioactive glasses that are devoid of alkali but still demonstrate high bioactivity in vitro. This article describes the in vivo performance of an alkali-free bioactive glass with the following composition (Wt %): 13.03 MgO-33.98 CaO-13.37 P2 O5 -38.84 SiO2 -0.77 CaF2 (labelled as FastOs(®) BG). An animal model was used to assess the in vivo performance of FastOs(®) BG, using 45S5 Bioglass(®) as control. The evaluation was performed through implantation of FastOs(®) BG and 45S5 Bioglass(®) , during one month, in femoral bone defects in sheep. Subcutaneous implantation of both glasses was also performed in order to assess tissue response through a standardized method. Histological and scanning electron microscopy assessment of retrieved subcutaneous and bone samples demonstrated that FastOs(®) BG is biocompatible, osteoconductive, that it can be osteointegrated, and that it is more slowly resorbed than 45S5 Bioglass(®) . These features suggest that FastOs(®) BG is a potential candidate for bone grafting. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 30-38, 2017.

  9. Local modification of speed of sound in lithium alumino-silicate glass/ceramic material by pulsed laser irradiation and thermal processing.

    PubMed

    Kim, Y; Helvajian, H

    2013-11-21

    Glass and glass/ceramics are now used in modern devices with increasing frequency. A list of the notable material properties commonly will not include a capability to guide ultrasonic waves. The photosensitive glass ceramics (PSGCs), an old invention with recent technological rebirth, may enable this capability. The speed of sound (SoS) has been measured at an ultrasonic frequency (75 MHz) in a commercially available PSGC material. The measurements are made using a pulse echo time-of-flight (TOF) technique as a function of UV laser exposure and thermal processing. The measured increase in the SoS correlates with the density of crystalline matter present, which can be metered by controlling the exposure dose. For the Li2SiO3 crystalline phase, the results show the shear (transverse) wave mode velocity can be increased by 4.8% relative to an unexposed area where no crystalline matter exists. The maximum change in velocity for the longitudinal (compressional) wave mode is only 2%. However, by altering the thermal processing protocols to grow the high temperature Li2Si2O5 crystalline phase, the measured change in the SoS increases to 11% and 9%, respectively. These results permit the volumetric patterning of delay lines by laser direct write techniques for generating complex profile ultrasonic wave patterns. Moreover, by patterned 3D shaping (i.e., photostructuring), ultrasound energy can be harnessed and utilized to advantage.

  10. Generation of alkali-free and high-proton concentration layer in a soda lime glass using non-contact corona discharge

    SciTech Connect

    Ikeda, Hiroshi; Sakai, Daisuke; Nishii, Junji; Funatsu, Shiro; Yamamoto, Kiyoshi; Suzuki, Toshio; Harada, Kenji

    2013-08-14

    Formation mechanisms of alkali-free and high-proton concentration surfaces were investigated for a soda lime glass using a corona discharge treatment under an atmospheric pressure. Protons produced by high DC voltage around an anode needle electrode were incorporated into a sodium ion site in the anode side glass. The sodium ion was swept away to the cathode side as a charge carrier. Then it was discharged. The precipitated sodium was transformed to a Na{sub 2}CO{sub 3} powder when the surface contacted with air. The sodium ion in the glass surface layer of the anode side was replaced completely by protons. The concentration of OH groups in the layer was balanced with the amount of excluded sodium ions. The substitution reaction of sodium ions with protons tends to be saturated according to a square root function of time. The alkali depletion layer formation rate was affected by the large difference in mobility between sodium ions and protons in the glass.

  11. Optical absorption and near infrared emission properties of Nd 3+ ions in alkali lead tellurofluoroborate glasses

    NASA Astrophysics Data System (ADS)

    Saleem, S. A.; Jamalaiah, B. C.; Kumar, J. Suresh; Babu, A. Mohan; Moorthy, L. Rama; Jayasimhadri, M.; Jang, Kiwan; Lee, Ho Sueb; Yi, Soung Soo; Jeong, Jung Hyun

    2009-12-01

    Nd 3+ doped H 3BO 3-PbO-TeO 2-RF (R = Li, Na and K) glasses were prepared through melt quenching technique. Optical absorption and near infrared (NIR) fluorescence spectra were recorded at room temperature. The spectral intensities were analyzed in terms of the Judd-Ofelt (J-O) parameters ( Ω λ = 2, 4, 6). The covalency effect of Nd-O bond on the J-O parameters was estimated from the relative absorbance ratio (R) between 4I 9/2 → 4F 7/2 and 4I 9/2 → 4S 3/2 transitions. The effect of Nd-O covalency on the Ω4 and Ω6 intensity parameters as well as on the spontaneous emission probabilities ( AR) was discussed. Lomheim and Shazer hybrid method was applied to determine the fluorescence branching ratios ( βR) of each emission transition from the 4F 3/2 metastable level to its lower lying levels. The evaluated total radiative transition probabilities ( AT), stimulated emission cross-sections ( σe) and gain bandwidth parameters ( σe × Δ λP) were compared with the earlier reports.

  12. Intumescence and pore structure of alkali-activated volcanic glasses upon exposure to high temperatures

    NASA Astrophysics Data System (ADS)

    Erdogan, S. T.

    2015-12-01

    Structures formed with ground perlite, a natural volcanic glass, activated with NaOH solutions, are shown to possess the ability to expand up to ~225 % of their original volumes upon exposure to temperatures in the 200-600 °C range. Porous solid with 3-7 MPa compressive strength and ˜450 kg/m3 or higher density are obtained. The observed expansion is believed to occur due to a loss of silanol condensation water, as vapor and is accompanied by an up to ~20 % loss in mass. A drop in pH to near-neutral values supports this idea. The size and total amount of pores in the final solid are controlled by concentration of the NaOH solution and thermal processing conditions. The pores formed are observed to be ~1-10 μm to mm-sized. The ability of perlite-based solids to intumesce over specific temperature ranges could be beneficial in applications where absorption of thermal energy is necessary, such as passive fire protection.

  13. Alkali-silica reactions of mortars produced by using waste glass as fine aggregate and admixtures such as fly ash and Li2CO3.

    PubMed

    Topçu, Ilker Bekir; Boğa, Ahmet Raif; Bilir, Turhan

    2008-01-01

    Use of waste glass or glass cullet (GC) as concrete aggregate is becoming more widespread each day because of the increase in resource efficiency. Recycling of wastes is very important for sustainable development. When glass is used as aggregate in concrete or mortar, expansions and internal stresses occur due to an alkali-silica reaction (ASR). Furthermore, rapid loss in durability is generally observed due to extreme crack formation and an increase in permeability. It is necessary to use some kind of chemical or mineral admixture to reduce crack formation. In this study, mortar bars are produced by using three different colors of glass in four different quantities as fine aggregate by weight, and the effects of these glass aggregates on ASR are investigated, corresponding to ASTM C 1260. Additionally, in order to reduce the expansions of mortars, 10% and 20% fly ash (FA) as mineral admixture and 1% and 2% Li(2)CO(3) as chemical admixture are incorporated by weight in the cement and their effects on expansion are examined. It is observed that among white (WG), green (GG) and brown glass (BG) aggregates, WG aggregate causes the greatest expansion. In addition, expansion increases with an increase in amount of glass. According to the test results, it is seen that over 20% FA and 2% Li(2)CO(3) replacements are required to produce mortars which have expansion values below the 0.2% critical value when exposed to ASR. However, usages of these admixtures reduce expansions occurring because of ASR.

  14. Specialty glass raw materials: Status and developments

    SciTech Connect

    Bauer, R.J.; Gray, S.L.

    1996-12-31

    The authors highlight several key raw materials used in the specialty glass industry. The focus here is to update changes and shifts underway in the worldwide availability and processes that will impact both costs and efficient use of these products. The glass types that use these materials generally are those other than container, float, and fiber glass. Those high-volume consumers of glass raw materials are discussed in a companion paper in this volume. In the specialty glass field, the batch materials involve minerals, and the chemicals derived from them, which are less readily available domestically. These are much more critically defined by specifications of assay, contamination, and particle size, resulting in their being more expensive. They are seldom commodity products. The scope of materials for this fragmented industry includes those for leads, borosilicates, aluminosilicates, opals, sealing and frit glasses, optical glass, ophthalmic glass, cathode ray tubes (CRTs) for TV and display, and glass-ceramics as major segments. They use lead oxides, nearly all the alkalies and alkaline earth portions of the periodic table, as well as rare earths, transition element oxides, phosphates, boron minerals and chemicals, zircon, zinc, most of the halogens, and many of the anions. They often require very special particle size specifications. The requirements for these batch materials are often based on chemistry, the absence of contaminants that impact melting, very wide ranges of the electromagnetic spectrum, glass homogeneity, and freedom from solid and gaseous inclusions down to ppm levels in both size and number.

  15. Mechanisms of optical losses in the {sup 5}D{sub 4} and {sup 5}D{sub 3} levels in Tb{sup 3+} doped low silica calcium aluminosilicate glasses

    SciTech Connect

    Santos, J. F. M. dos; Terra, I. A. A.; Nunes, L. A. O.; Catunda, T.; Astrath, N. G. C.; Guimarães, F. B.; Baesso, M. L.

    2015-02-07

    Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb{sup 3+}-doped low silica calcium aluminosilicate glasses are analyzed for UV (λ{sub exc} = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb{sup 3+} concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5–15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb{sup 3+} concentrations. Cooperative upconversion from a pair of excited ions ({sup 5}D{sub 3}:{sup 5}D{sub 3} or {sup 5}D{sub 3}:{sup 5}D{sub 4}) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.

  16. Results of Aluminosilicate Formation Testing

    SciTech Connect

    Wilmarth, W.R.

    2001-09-11

    The purpose of this work was to examine several experimental parameters of the formation of aluminosilicates under several tank chemistries, examine the conversion of crystalline phases, and determine inherent solubilities of certain crystal phases.

  17. Effects of chemical composition on the environments of D+ and H+ in alkali silicate glasses: with implications for D/H fractionation in magmatic processes

    NASA Astrophysics Data System (ADS)

    Le Losq, C.; Cody, G. D.; Mysen, B. O.

    2014-12-01

    The δD is an important probe for studying the cycle of water within the Earth and between planetary bodies. D/H fractionation between silicate melts, minerals, aqueous fluids and gases governed the δD-evolution of the various geochemical reservoirs. It is usually assumed that D+ and H+ have the same chemical properties and structural environments in silicate melts and aqueous fluids, so that the only mass-dependent fractionation takes place with values approaching 1 at magmatic temperatures. However, recent in situ studies reveal important D/H fractionation between silicate melts and aqueous fluids even at high temperature. H and D MAS NMR data from sodium silicate glasses also shown that D+ and H+ occupy different structural positions in the structure of silicate glasses. This suggests that mass-dependent fractionation is not the only factor governing D/H fractionation in magmatic systems. To assess how the chemical composition and the structure of alkali silicate glasses affect the environments of H+ and D+, the H and D MAS NMR spectra of M2Si4O9 glasses (M = Li, Na or K) with different concentrations of pure H2O or D2O (from 3.3 up to 17.6 mol%) were recorded. Other spectra were acquired from M2Si4O9 glasses with 17.6 mol%(1H,1D)2O. Signals at ~1, ~3.5, ~5, ~12 and ~16 ppm in 1H MAS NMR spectra are assigned to H+ in H2O molecules and Si-OH groups in the glasses. These five signals indicates protons distribution between at least five environments with O…O distances ranging from ~305 to ~240 pm. The ionic radius of alkali affects the distribution of H+ between those environments. D MAS NMR spectra reveal that by exchanging H+ with D+, the intensity of the 16 ppm NMR line increases, whereas the intensity of the 5 ppm line decreases. Consequently, D+ seems to be more concentrated than H+ in environments with small O...O distances. In other words, the structural environments of H+ and D+ in the silicate glasses, and hence in melts at their glass transition

  18. Investigation of the local structure of Cu2+ ions doped in alkali lead tetraborate glasses by their electron paramagnetic resonance and optical spectra

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Chen, Zhi

    2014-06-01

    The local structure of the Cu2+ centers in alkali lead tetraborate glasses was theoretically studied based on the optical spectra data and high-order perturbation formulas of the spin Hamiltonian parameters (electron paramagnetic resonance g factors g∥, g⊥ and hyperfine structure constants A∥, A⊥) for a 3d9 ion in a tetragonally elongated octahedron. In these formulas, the relative axial elongation of the ligand O2- octahedron around the Cu2+ due to the Jahn-Teller effect is taken into account by considering the contributions to the g factors from the tetragonal distortion which is characterized by the tetragonal crystal-field parameters Ds and Dt. From the calculations, the ligand O2- octahedral around Cu2+ is determined to suffer about 19.2% relative elongation along the C4 axis of the alkali lead tetraborate glass system, and a negative sign for A∥ and a positive sign for A⊥ for these Cu2+ centers are suggested in the discussion.

  19. Computer simulation study of low-energy excitations of silicate glasses

    NASA Astrophysics Data System (ADS)

    Palin, Erika J.; Trachenko, Kostya O.; Dove, Martin T.

    2002-05-01

    Ten silicate and aluminosilicate glasses with different number densities and connectivities were studied by molecular dynamics simulation using the computer program DL_POLY [1]. The radial distribution functions, phonon densities of states and flexibilities of the glass networks were determined, and compared with those determined for silica [2]. The large-scale flexibility of silica was found to be similar to that of some of the glasses studied in this work, particularly in relation to rigid-unit-mode-type motions. The degree of localization of vibrations in fully networked glasses was found to be similar to that in silica, but the vibrations in glasses containing non-bridging oxygen atoms were found to be more localized. This is thought to be due to clustering of alkali cations, which in turn necessarily produces clusters of tetrahedra.

  20. Influence of ZnO/MgO substitution on sintering, crystallisation, and bio-activity of alkali-free glass-ceramics.

    PubMed

    Kapoor, Saurabh; Goel, Ashutosh; Correia, Ana Filipa; Pascual, Maria J; Lee, Hye-Young; Kim, Hae-Won; Ferreira, José M F

    2015-08-01

    The present study reports on the influence of partial replacement of MgO by ZnO on the structure, crystallisation behaviour and bioactivity of alkali-free bioactive glass-ceramics (GCs). A series of glass compositions (mol%): 36.07 CaO-(19.24-x) MgO-x ZnO-5.61 P2O5-38.49 SiO2-0.59 CaF2 (x=2-10) have been synthesised by melt-quench technique. The structural changes were investigated by solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR), X-ray diffraction and differential thermal analysis. The sintering and crystallisation behaviours of glass powders were studied by hot-stage microscopy and differential thermal analysis, respectively. All the glass compositions exhibited good densification ability resulting in well sintered and mechanically strong GCs. The crystallisation and mechanical behaviour were studied under non-isothermal heating conditions at 850 °C for 1h. Diopside was the primary crystalline phase in all the GCs followed by fluorapatite and rankinite as secondary phases. Another phase named petedunnite was identified in GCs with ZnO content >4 mol. The proliferation of mesenchymal stem cells (MSCs) and their alkaline phosphatase activity (ALP) on GCs was revealed to be Zn-dose dependent with the highest performance being observed for 4 mol% ZnO.

  1. Study of structural and spectroscopic behavior of Sm3+ ions in lead-zinc borate glasses containing alkali metal ions

    NASA Astrophysics Data System (ADS)

    Sasi Kumar, M. V.; Babu, S.; Rajeswara Reddy, B.; Ratnakaram, Y. C.

    2017-02-01

    High luminescence behavior of rare earth inorganic glasses have a variety of uses in the industry. In the past few decades, rare earth ions with characteristic photonics applications are being hosted by heavy metal oxide glasses. Among the rare earth ions Sm3+ ion has features which make it apt for high density optical storage. The authors of the paper have experimented to synthesize Sm3+ doped glasses. In this regard a new series of borate glasses doped with 1 mol% Sm3+ ion are developed by using melt-quenching technique. XRD, FTIR, optical absorption, luminescence techniques are used to study the various characteristics of Sm3+ ion in the present glass matrices. The XRD spectra confirms the amorphous nature of glasses. Further, the researchers have used differential thermal analysis to study the glass transition temperature. The structural groups in the prepared glasses are studied using Fourier transform infrared spectra. From the measurement of its optical absorption, three phenomenological Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) have been computed. Based on these Judd-Ofelt intensity parameters, radiative properties such as radiative probabilities (Arad), branching ratios (β), and radiative life time (τR) are calculated. The excitation spectra of Sm3+ doped lithium heavy metal borate glass matrix is recorded under the emission wavelength of 600 nm. The emission spectra are recorded under 404 nm excitation wavelength. From various emission transitions, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 bands could be of interest for various applications. The decay profiles of 4G5/2 level exhibit single exponential nature in all the prepared glass matrices. The potassium glass matrix exhibits higher quantum efficiency than the other glass matrices. Finally, by going through these several spectroscopic characterizations, it is concluded that the prepared Sm3+ doped lead-zinc borate glasses might be useful for visible light applications.

  2. Two-point bend studies of glass fibers

    NASA Astrophysics Data System (ADS)

    Tang, Zhongzhi

    The principal objective of this research is to advance our understanding of how glass breaks. Glass, a material well known for its brittleness, has been used widely but within a frustrating limit of its strength. Generally, strength is not considered as an intrinsic property of glass, due to the difficulty of avoiding the presence of flaws on the sample surface. The fiber drawing system and two-point bending (TPB) equipment developed at Missouri S&T allow the fabrication of pristine glass fibers and failure strain measurements while minimizing the effects of strength limiting critical flaws. Several conditions affect the failure behavior of glasses, including glass composition, thermal history of melts and environmental conditions during the failure tests. Understanding how these conditions affect failure helps us understand how glass fails. In this dissertation, failure strains for many different silicate and borate glasses were measured under a variety of experimental conditions. Failure stresses for various silicate glasses were calculated using values of the nonlinear elastic moduli reported in the literature. Inert intrinsic strengths for alkali silicate glasses were related to the structure and corresponding bond strengths, and the dependence of the inert strengths on faceplate velocity is discussed. Inert failure strains were also obtained for sodium borate glasses. Up to ˜40% failure strain was measured for vitreous B2O 3. The addition of soda to boron oxide increases the dimensionality and connectivity of the glass structure and hence increases its resistance to deformation, as was observed in elasticity and brittleness measurements reported in the literature. The increase in deformation resistance produces lower failure strains, a behavior also seen for alkali silicate and aluminosilicate glasses where the reduction of non-bridging oxygen increases the structure stiffness and leads to lower inert failure strain. Fatigue effects on silicate glasses were

  3. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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  4. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2727 Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance. This substance is generally recognized...

  5. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  6. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  7. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  8. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  9. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  10. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  11. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  12. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  13. Development of Li+ alumino-silicate ion source

    SciTech Connect

    Roy, P.K.; Seidl, P.A.; Waldron, W.; Greenway, W.; Lidia, S.; Anders, A.; Kwan, J.

    2009-04-21

    To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, one strategy is to deposit most of the ion energy at the peak of energy loss (dE/dx) with a low (E< 5 MeV) kinetic energy beam and a thin target[1]. Lower mass ions have a peak dE/dx at a lower kinetic energy. To this end, a small lithium (Li+) alumino-silicate source has been fabricated, and its emission limit has been measured. These surface ionization sources are heated to 1000-1150 C where they preferentially emit singly ionized alkali ions. Alumino-silicates sources of K+ and Cs+ have been used extensively in beam experiments, but there are additional challenges for the preparation of high-quality Li+ sources: There are tighter tolerances in preparing and sintering the alumino-silicate to the substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. We report on recent measurements ofhigh ( up to 35 mA/cm2) current density from a Li+ source. Ion species identification of possible contaminants is being verified with a Wien (E x B) filter, and via time-of-flight.

  14. Optical Properties of K2O-Li2O-WO3-B2O3 Glasses: Evidence of Mixed Alkali Effect

    NASA Astrophysics Data System (ADS)

    Edukondalu, Avula; Sripathi, T.; Kareem Ahmmad, Shaik; Rahman, Syed; Sivakumar, K.

    2017-02-01

    Glass with compositions xK2O-(30 - x)Li2O-10WO3-60B2O3 for 0 ≤ x ≤ 30 mol.% have been prepared using the normal melt quenching technique. The optical reflection and absorption spectra were recorded at room temperature in the wavelength range 300-800 nm. From the absorption edge studies, the values of the optical band gap ( E opt) and Urbach energy (Δ E) have been evaluated. The values of E opt and Δ E vary non-linearly with composition parameter, showing the mixed alkali effect. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple Di-Domenico model.

  15. The development of a potassium-sulfide glass fiber cell and studies on impurities in alkali metal-sulfur cells

    NASA Technical Reports Server (NTRS)

    Tsang, F. Y.

    1977-01-01

    Potassium sulfur rechargeable cells, having as the electrolyte the thin walls of hollow glass fibers made from permeable glass, were developed. The cells had short lives, probably due to the construction materials and impurities in the potassium. The effect of the impurities in the analogous NA-S system was studied. Calcium, potassium, and NaOH/oxide impurities caused increased resistance or corrosion of the glass fibers. For long lived cell operation, the Na must contain less than 1 ppm Ca and less than a few ppm of hydroxide/oxide. Up to 150 ppm K can be tolerated. After purification of the Na anolyte, cell lifetimes in excess of 1000 deep charge-discharge cycles or over 8 months on continuous cycling at 10-30 percent depth of discharge were obtained.

  16. Ion Exchange in Glass-Ceramics

    NASA Astrophysics Data System (ADS)

    Beall, George; Comte, Monique; Deneka, Matthew; Marques, Paulo; Pradeau, Philippe; Smith, Charlene

    2016-08-01

    In the past few years ion-exchange in glasses has found a renewed interest with a lot of new development and research in industrial and academic labs and the commercialization of materials with outstanding mechanical properties. These glasses are now widely used in many electronic devices including hand-held displays and tablets. The exchange is generally conducted in a bath of molten salt below the transition temperature of the glass. The exchange at the surface of an alkali ion by a bigger one brings compressive stress at the surface. The mechanical properties are dependent on the stress level at the surface and the depth of penetration of the bigger ion. As compared to glasses, glass-ceramics have the interest to display a wide range of aspects (transparent to opaque) and different mechanical properties (especially higher modulus and toughness). There has been little research on ion-exchange in glass-ceramics. In these materials the mechanisms are much more complex than in glasses because of their polyphasic nature: ion-exchange generally takes place mostly in one phase (crystalline phase or residual glass). The mechanism can be similar to what is observed in glasses with the replacement of an ion by another in the structure. But in some cases this ion-exchange leads to microstructural modifications (for example amorphisation or phase change). This article reviews these ion-exchange mechanisms using several transparent and opaque alumino-silicate glass-ceramics as examples. The effect of the ion exchange in the various glass-ceramics will be described, with particular emphasis on flexural strength.

  17. Influence of ZnO on optical properties and dc conductivity of vanadyl-doped alkali bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Gahlot, P. S.; Seth, V. P.; Agarwal, A.; Kishore, N.; Gupta, S. K.; Arora, M.; Goyal, D. R.

    2004-04-01

    A new family of glasses based on Bi2O3 was found in the systems x ZnO . (0.30 - x )M2O . 0.70Bi(2)O(3) (M = Li, Na) in the range 0.00 less than or equal to x less than or equal to 0.20 containing 2.0 mol% of V2O5 . Density, molar volume, optical band gap and dc conductivity of these glasses have been investigated. The position of the absorption edge and hence the value of the optical band gap has been reported.

  18. Structure of iron phosphate glasses modified by alkali and alkaline earth additions: neutron and x-ray diffraction studies.

    PubMed

    Bingham, P A; Barney, E R

    2012-05-02

    The structure of iron phosphate glasses modified by additions of K(2)O and BaO, with nominal molar compositions [(1 - x)(0.6P(2)O(5)-0.4Fe(2)O(3))]xMe(y)O, where x = 0-0.4 in increments of 0.1; Me=K or Ba; and y = 1 or 2, has been investigated using neutron diffraction and x-ray diffraction techniques. Fitted coordination numbers for P-O and Fe-O showed a notable change in the P-O(NBO) and P-O(BO) contributions at greater than 20 mol% modifier addition, with barium producing a markedly larger increase in P-O(NBO) contribution than potassium. Fitting of T(N)(r) and T(X)(r) provided average n(BaO) = 9 and n(KO) = 6. Iron occurs in a range of coordination sites in these glasses: ([6])Fe(2+), ([4])Fe(3+), ([5])Fe(3+) and ([6])Fe(3+). The partitioning between these sites gives average n(FeO) = 5.2-5.8, with barium-doped glasses exhibiting higher average n(FeO) than potassium-doped glasses. The stronger depolymerizing effect of Ba(2+) than K(+) on the phosphate network, coupled with its greater ionic charge and higher Me-O, Fe-O and O···O coordination numbers, explain previously observed divergences in physical properties between the barium-doped and the potassium-doped glasses.

  19. Aluminosilicate Precipitation Impact on Uranium

    SciTech Connect

    WILMARTH, WILLIAM

    2006-03-10

    Experiments have been conducted to examine the fate of uranium during the formation of sodium aluminosilicate (NAS) when wastes containing high aluminate concentrations are mixed with wastes of high silicate concentration. Testing was conducted at varying degrees of uranium saturation. Testing examined typical tank conditions, e.g., stagnant, slightly elevated temperature (50 C). The results showed that under sub-saturated conditions uranium is not removed from solution to any large extent in both simulant testing and actual tank waste testing. This aspect was not thoroughly understood prior to this work and was necessary to avoid criticality issues when actual tank wastes were aggregated. There are data supporting a small removal due to sorption of uranium on sites in the NAS. Above the solubility limit the data are clear that a reduction in uranium concentration occurs concomitant with the formation of aluminosilicate. This uranium precipitation is fairly rapid and ceases when uranium reaches its solubility limit. At the solubility limit, it appears that uranium is not affected, but further testing might be warranted.

  20. Microstructural and phase evolution in metakaolin geopolymers with different activators and added aluminosilicate fillers

    NASA Astrophysics Data System (ADS)

    Sarkar, Madhuchhanda; Dana, Kausik; Das, Sukhen

    2015-10-01

    This work aims to investigate the microstructural and phase evolution of alkali activated metakaolin products with different activators and added aluminosilicate filler phases. The added filler phases have different reactivity to the alkali activated metakaolin system. Microstructural evolution in the alkali activated products has been investigated by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM). Variation in strength development in alkali activated metakaolin products was followed by compressive strength measurement test. Microstructural study shows that in case of metakaolin with NaOH activator crystalline sodalite formed in all the product samples irrespective of the added filler phases. The microstructure of these NaOH activated products investigated by FESEM showed crystalline and inhomogeneous morphology. Mixed activator containing both NaOH and sodium silicate in a fixed mass ratio formed predominantly amorphous phase. Microstructure of these samples showed more homogeneity than that of NaOH activated metakaolin products. The study further shows that addition of α-Al2O3 powder, non reactive phase to the alkali activated metakaolin system when used in larger amount increased crystalline phase in the matrix. α-Al2O3 powder addition increased the compressive strength of the product samples for both the activator compositions. Added phase of colloidal silica, reactive to the alkali activated metakaolin system when used in larger amount was found to increase amorphous nature of the matrix. Addition of colloidal silica influenced the compressive strength property differently with different activator compositions.

  1. Method of handling radioactive alkali metal waste

    DOEpatents

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

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

  2. Method of handling radioactive alkali metal waste

    DOEpatents

    Wolson, Raymond D.; McPheeters, Charles C.

    1980-01-01

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

  3. Structural and redox effects in iron-doped magnesium aluminosilicates

    NASA Astrophysics Data System (ADS)

    Ferreira, N. M.; Kovalevsky, A. V.; Valente, M. A.; Waerenborgh, J. C.; Frade, J. R.; Costa, F. M.

    2017-01-01

    Magnesium aluminosilicates (MAS) represent a great importance for many electrical and catalytic applications. Recently, MAS-based glasses were considered as prospective for use as an electrolyte in steel making by molten oxide electrolysis process, an alternative electrometallurgical technique which offers prospects for environmental and economic advantages over traditional steelmaking. In the present work, low-iron content MAS glasses were processed by an unconventional method: the laser floating zone (LFZ), to simulate the strongly-nonequilibrium high-temperature conditions which may arise during pyroelectrolysis process. The work focuses on the effect of pulling rate on crystallization kinetics, taking into account structural, electrical and magnetic properties of the as-grown material. The results revealed that faster pulling rates promote formation of isolated iron cations in the glass forming network. The crystallization process is strongly affected by lower pulling rates. LFZ method shows good prospects for studying the crystallization mechanisms in silicate-based glasses with additions of redox-active cations, by providing flexibility in tuning their oxidation state and crystalline/amorphous conditions.

  4. Dissolution and Separation of Aluminum and Aluminosilicates

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  5. Dissolution and Separation of Aluminum and Aluminosilicates

    DOE PAGES

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

  6. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  7. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  8. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  9. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  10. An investigation of waste glass-based geopolymers supplemented with alumina

    NASA Astrophysics Data System (ADS)

    Christiansen, Mary U.

    An increased consideration of sustainability throughout society has resulted in a surge of research investigating sustainable alternatives to existing construction materials. A new binder system, called a geopolymer, is being investigated to supplement ordinary portland cement (OPC) concrete, which has come under scrutiny because of the CO2 emissions inherent in its production. Geopolymers are produced from the alkali activation of a powdered aluminosilicate source by an alkaline solution, which results in a dense three-dimensional matrix of tetrahedrally linked aluminosilicates. Geopolymers have shown great potential as a building construction material, offering similar mechanical and durability properties to OPC. Additionally, geopolymers have the added value of a considerably smaller carbon footprint than OPC. This research considered the compressive strength, microstructure and composition of geopolymers made from two types of waste glass with varying aluminum contents. Waste glass shows great potential for mainstream use in geopolymers due to its chemical and physical homogeneity as well as its high content of amorphous silica, which could eliminate the need for sodium silicate. However, the lack of aluminum is thought to negatively affect the mechanical performance and alkali stability of the geopolymer system. 39 Mortars were designed using various combinations of glass and metakaolin or fly ash to supplement the aluminum in the system. Mortar made from the high-Al glass (12% Al2O3) reached over 10,000 psi at six months. Mortar made from the low-Al glass (<1% Al2O3) did not perform as well and remained sticky even after several weeks of curing, most likely due to the lack of Al which is believed to cause hardening in geopolymers. A moderate metakaolin replacement (25-38% by mass) was found to positively affect the compressive strength of mortars made with either type of glass. Though the microstructure of the mortar was quite indicative of mechanical

  11. Phase evolution of Na2O-Al2O3-SiO2-H2O gels in synthetic aluminosilicate binders.

    PubMed

    Walkley, Brant; San Nicolas, Rackel; Sani, Marc-Antoine; Gehman, John D; van Deventer, Jannie S J; Provis, John L

    2016-04-07

    This study demonstrates the production of stoichiometrically controlled alkali-aluminosilicate gels ('geopolymers') via alkali-activation of high-purity synthetic amorphous aluminosilicate powders. This method provides for the first time a process by which the chemistry of aluminosilicate-based cementitious materials may be accurately simulated by pure synthetic systems, allowing elucidation of physicochemical phenomena controlling alkali-aluminosilicate gel formation which has until now been impeded by the inability to isolate and control key variables. Phase evolution and nanostructural development of these materials are examined using advanced characterisation techniques, including solid state MAS NMR spectroscopy probing (29)Si, (27)Al and (23)Na nuclei. Gel stoichiometry and the reaction kinetics which control phase evolution are shown to be strongly dependent on the chemical composition of the reaction mix, while the main reaction product is a Na2O-Al2O3-SiO2-H2O type gel comprised of aluminium and silicon tetrahedra linked via oxygen bridges, with sodium taking on a charge balancing function. The alkali-aluminosilicate gels produced in this study constitute a chemically simplified model system which provides a novel research tool for the study of phase evolution and microstructural development in these systems. Novel insight of physicochemical phenomena governing geopolymer gel formation suggests that intricate control over time-dependent geopolymer physical properties can be attained through a careful precursor mix design. Chemical composition of the main N-A-S-H type gel reaction product as well as the reaction kinetics governing its formation are closely related to the Si/Al ratio of the precursor, with increased Al content leading to an increased rate of reaction and a decreased Si/Al ratio in the N-A-S-H type gel. This has significant implications for geopolymer mix design for industrial applications.

  12. Geopolymers and Related Alkali-Activated Materials

    NASA Astrophysics Data System (ADS)

    Provis, John L.; Bernal, Susan A.

    2014-07-01

    The development of new, sustainable, low-CO2 construction materials is essential if the global construction industry is to reduce the environmental footprint of its activities, which is incurred particularly through the production of Portland cement. One type of non-Portland cement that is attracting particular attention is based on alkali-aluminosilicate chemistry, including the class of binders that have become known as geopolymers. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint and with the potential for performance advantages over traditional cements in certain niche applications. This review discusses the synthesis of alkali-activated binders from blast furnace slag, calcined clay (metakaolin), and fly ash, including analysis of the chemical reaction mechanisms and binder phase assemblages that control the early-age and hardened properties of these materials, in particular initial setting and long-term durability. Perspectives for future research developments are also explored.

  13. Secondary Ion Mass Spectrometry of Zeolite Materials: Observation of Abundant Aluminosilicate Oligomers Using an Ion Trap

    SciTech Connect

    Groenewold, Gary Steven; Kessinger, Glen Frank; Scott, Jill Rennee; Gianotto, Anita Kay; Appelhans, Anthony David; Delmore, James Edward

    2000-12-01

    Oligomeric oxyanions were observed in the secondary ion mass spectra (SIMS) of zeolite materials. The oxyanions have the general composition AlmSinO2(m+n)H(m-1)- (m + n = 2 to 8) and are termed dehydrates. For a given mass, multiple elemental compositions are possible because (Al + H) is an isovalent and isobaric substitute for Si. Using 18 keV Ga+ as a projectile, oligomer abundances are low relative to the monomers. Oligomer abundance can be increased by using the polyatomic projectile ReO4- (~5 keV). Oligomer abundance can be further increased using an ion trap (IT-) SIMS; in this instrument, long ion lifetimes (tens of ms) and relatively high He pressure result in significant collisional stabilization and increased high-mass abundance. The dehydrates rapidly react with adventitious H2O present in the IT-SIMS to form mono-, di-, and trihydrates. The rapidity of the reaction and comparison to aluminum oxyanion hydration suggest that H2O adds to the aluminosilicate oxyanions in a dissociative fashion, forming covalently bound product ions. In addition to these findings, it was noted that production of abundant oligomeric aluminosilicates could be significantly increased by substituting the countercation (NH4+) with the larger alkali ions Rb+ and Cs+. This constitutes a useful tactic for generating large aluminosilicate oligomers for surface characterization and ion-molecule reactivity studies.

  14. Physical and optical properties of Co{sup 2+}, Ni{sup 2+} doped 20ZnO + xLi{sub 2}O + (30 − x)K{sub 2}O + 50B{sub 2}O{sub 3} (5 ≤ x ≤ 25) glasses: Observation of mixed alkali effect

    SciTech Connect

    Krishna Kumari, G.; Muntaz Begum, Sk.; Rama Krishna, Ch.; Sathish, D.V.; Murthy, P.N.; Rao, P.S.; Ravikumar, R.V.S.S.N.

    2012-09-15

    Graphical abstract: Composition dependence of density and Urbach energy of Co{sup 2+} and Ni{sup 2+} doped ZLKB glasses: (a) Co{sup 2+} doped glasses and (b) Ni{sup 2+} doped glasses. Both are exhibited mixed alkali effect. Highlights: ► Mixed alkali effect is observed. ► Band gap studies indicate that the glasses are structural stable. ► The glasses are observed to be partially covalent in nature. -- Abstract: Co{sup 2+} and Ni{sup 2+} ions doped 20ZnO + xLi{sub 2}O + (30 − x) K{sub 2}O + 50B{sub 2}O{sub 3} (5 ≤ x ≤ 25) mol% glasses are prepared using melt quenching technique. Structural changes of the prepared glasses by addition of transition metal oxides, CoO and NiO are investigated by UV–vis–NIR, FT-IR spectroscopy and XRD. The XRD pattern indicates the amorphous nature of prepared glasses. FT-IR measurements of the all glasses revealed that the network structure of the glasses are mainly based on BO{sub 3} and BO{sub 4} units placed in different structural groups in which the BO{sub 3} units being dominant. The optical absorption spectra suggest the site symmetry of Co{sup 2+} and Ni{sup 2+} ions in the glasses are near octahedral. Crystal field and inter-electronic repulsion parameters are also evaluated. The optical band gap and Urbach energies exhibited the mixed alkali effect. Various physical parameters such as density, refractive index, optical dielectric constant, polaron radius, electronic polarizability and inter-ionic distance are also determined.

  15. Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

    SciTech Connect

    Bobkov, K K; Rybaltovsky, A A; Vel'miskin, V V; Likhachev, M E; Bubnov, M M; Dianov, E M; Umnikov, A A; Gur'yanov, A N; Vechkanov, N N; Shestakova, I A

    2014-12-31

    We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)

  16. Glass/BNNT Composite for Sealing Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Hurst, Janet B.; Choi, Sung R.

    2007-01-01

    A material consisting of a barium calcium aluminosilicate glass reinforced with 4 weight percent of boron nitride nanotubes (BNNTs) has shown promise for use as a sealant in planar solid oxide fuel cells (SOFCs).

  17. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  18. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  19. Solubility and solution mechanisms of chlorine in aluminosilicate melts at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Dalou, C.; Mysen, B. O.

    2012-12-01

    We address the effect of alkalies and aluminum on the solution behavior of Cl by combining solubility measurements of Cl and Raman data of Cl-bearing peralkaline aluminosilicate glasses (quenched melt). Six compositions along the join Na2Si3O7(NS3)-Na2(NaAl)3O7 and six compositions along the join K2Si3O7(KS3)-K2(KAl)3O7 were used. In order to isolate potential effects of Al/(Al+Si) from changes on melt polymerization, Al2O3 was exchanged with SiO2 in a charge-balanced form, NaAlO2 and KaAlO2 thus keeping approximately constant NBO/T (0.65 ± 0.02) for all melts (assuming Al3+ in 4-fold coordination in the melts). Starting materials were doped with 5wt% Cl in the form of PdCl2, which releases Cl2 as its gaseous phase during experiment. Samples were synthetized on piston-cylinder apparatus at 1600°C - 1.5 GPa. At the end of the experiments, Pd forms little spheres (1-2 μm) that for most part dissolves into the capsule. Chlorine oversaturation in the melts is ensured by the observation of bubbles in the quenched samples. The Cl solubility in Na-bearing systems is about twice that of the than in K-bearing system and may, therefore, be negatively correlated with ionic radius of the metal cation.. The solubility also decreases with Al/(Al+Si). In NS3 system, it decreases from 4.01 ± 0.13 wt% of Cl in Al-free systems to 1.87 ± 0.19 wt% of Cl for an Al/Al+Si ratio of 0.34. In KS3 system, this decrease is from 2.23 ± 0.08 wt% of Cl in Al-free systems to 0.62 ± 0.05 wt% of Cl for an Al/Al+Si ratio of 0.36. In Al-free systems, preliminary Raman data show the appearance of a peak around 465cm-1, that we assigned to alkali-Cl bonding. The intensity of this 465cm-1 peak increases with Al content confirming the role of Al in Cl solution mechanism.We also identify the molecular Cl peak at 1540cm-1. The peak can be detected only in Al-bearing melts. The Al substitution for Si results in increased abundance of three-dimensional cages on the melt structure into which molecular

  20. Broadband infrared light-emitting patterns in optical glass by laser-induced nanostructuring of NiO-doped alkali-gallium germanosilicates.

    PubMed

    Lotarev, S V; Lipatiev, A S; Golubev, N V; Ignat'eva, E S; Malashkevich, G E; Mudryi, A V; Priseko, Y S; Lorenzi, R; Paleari, A; Sigaev, V N

    2013-02-15

    In this Letter, we show functionalization of NiO-doped 7.5Li(2)O·2.5Na(2)O·20Ga(2)O(3)·35SiO(2)·35GeO(2) glass by space-selective nanocrystallization via exposure to the focused beam of a pulsed copper vapor laser (510.6 and 578.2 nm) at temperature close to the glass transition point (570°C). Irradiated areas drastically change their color, caused by electronic transitions of Ni(2+) dopant ions, without any alteration of the optical quality. Importantly, irradiated regions acquire broadband infrared luminescence (centered at about 1400 nm and possessing 400 nm effective bandwidth) typical of Ni(2+) ions in crystalline environment, and by positive change of refractive index (more than 10(-3)). Spectroscopic and diffractometric data of the irradiated regions indeed resemble those previously observed in thermally nanocrystallized glass, with Ni(2+) ions embedded in γ-Ga(2)O(3) nanocrystals. The results demonstrate the possibility of laser writing nanocrystallized multifunction patterns in germanosilicate glasses for the fabrication of active integrated devices.

  1. Calcium-magnesium Aluminosilicate (CMAS) Interactions with Advanced Environmental Barrier Coating Material

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    Particulates, like sand and volcanic ash, threaten the development of robust environmental barrier coatings (EBCs) that protect next-generation silicon-based ceramic matrix composite (CMC) turbine engine components from harsh combustion environments during service. The siliceous particulates transform into molten glassy deposits of calcium-magnesium aluminosilicate (CMAS) when ingested by an aircraft engine operating at temperatures above 1200C. In this study, a sample of desert sand was melted into CMAS glass to evaluate high-temperature interactions between the sand glass and an advanced EBC material. Desert sand glass was added to the surface of hot-pressed EBC substrates, which were then heated in air at temperatures ranging from 1200C to 1500C. Scanning electron microscopy and X-ray energy-dispersive spectroscopy were used to evaluate microstructure and phase compositions of specimens and the CMASEBC interface after heat treatments.

  2. Uranium and Aluminosilicate Surface Precipitation Tests

    SciTech Connect

    Hu, M.Z.

    2002-11-27

    The 2H evaporator at the Savannah River Site has been used to treat an aluminum-rich waste stream from canyon operations and a silicon-rich waste stream from the Defense Waste Processing Facility. The formation of aluminosilicate scale in the evaporator has caused significant operational problems. Because uranium has been found to accumulate in the aluminosilicate solids, the scale deposition has introduced criticality concerns as well. The objective of the tests described in this report is to determine possible causes of the uranium incorporation in the evaporator scale materials. The scope of this task is to perform laboratory experiments with simulant solutions to determine if (1) uranium can be deposited on the surfaces of various sodium aluminosilicate (NAS) forms and (2) aluminosilicates can form on the surfaces of uranium-containing solids. Batch experiments with simulant solutions of three types were conducted: (1) contact of uranium solutions/sols with NAS coatings on stainless steel surfaces, (2) contact of uranium solutions with NAS particles, and (3) contact of precipitated uranium-containing particles with solutions containing aluminum and silicon. The results show that uranium can be incorporated in NAS solids through encapsulation in bulk agglomerated NAS particles of different phases (amorphous, zeolite A, sodalite, and cancrinite) as well as through heterogeneous deposition on the surfaces of NAS coatings (amorphous and cancrinite) grown on stainless steel. The results also indicate that NAS particles can grow on the surfaces of precipitated uranium solids. Particularly notable for evaporator operations is the finding that uranium solids can form on existing NAS scale, including cancrinite solids. If NAS scale is present, and uranium is in sufficient concentration in solution to precipitate, a portion of the uranium can be expected to become associated with the scale. The data obtained to date on uranium-NAS affinity are qualitative. A necessary

  3. Granulation of zeolite-containing aluminosilicate hydrogel

    SciTech Connect

    Galimov, Z.F.; Vinkel'man, A.P.

    1987-09-01

    The granulation of aluminosilicate hydrogel as an intermediate for the synthesis of cracking catalysts was investigated from the standpoint of eliminating the splitting cone from the granulator and eliminating coagulation directly on the cone surface. A method for forming the gel without a cone was developed by dispersion of jets of sol issuing directly from the mixer. Gel quality was considerably higher in dispersions of time-constant jets of the sol. The experimental mixer can be used as a design basis for a multijet granulator with a capacity equivalent to one or several splitting cones in commercial units.

  4. Alteration layer formation of Ca- and Zn-oxide bearing alkali borosilicate glasses for immobilisation of UK high level waste: A vapour hydration study

    NASA Astrophysics Data System (ADS)

    Cassingham, N. J.; Corkhill, C. L.; Stennett, M. C.; Hand, R. J.; Hyatt, N. C.

    2016-10-01

    The UK high level nuclear waste glass modified with CaO/ZnO was investigated using the vapour phase hydration test, performed at 200 °C, with the aim of understanding the impact of the modification on the chemical composition and microstructure of the alteration layer. Experiments were undertaken on non-modified and CaO/ZnO-modified base glass, with or without 25 wt% of simulant Magnox waste calcine. The modification resulted in a dramatic reduction in gel layer thickness and also a reduction in the reaction rate, from 3.4 ± 0.3 g m-2 d-1 without CaO/ZnO modification to 0.9 ± 0.1 g m-2 d-1 with CaO/ZnO. The precipitated phase assemblage for the CaO/ZnO-modified compositions was identified as hydrated Ca- and Zn-bearing silicate phases, which were absent from the non-modified counterpart. These results are in agreement with other recent studies showing the beneficial effects of ZnO additions on glass durability.

  5. Tensile and creep behavior of a silicon carbide fiber-reinforced aluminosilicate composite

    SciTech Connect

    Khobaib, M.; Zawada, L.

    1991-08-01

    Tensile and tensile creep tests were conducted with a Nicalon/aluminosilicate (Si-C-O/1723) glass composite. Tensile tests were conducted at room temperature, and the creep tests were conducted at 600, 700, and 750 C. Room temperature tensile test failure features exhibited a tortuous crack path and extensive fiber pull-out. The failure features in creep were characterized by flat fracture and little fiber pull-out. The environment appeared to play a significant role in creep failure of this composite system. 6 refs.

  6. The effect of boron oxide on the composition, structure, and adsorptivity of glass surfaces

    NASA Astrophysics Data System (ADS)

    Schaut, Robert A.

    Boron oxide has been added to commercial silicate glasses for many years to aid in lowering melting temperatures, lowering thermal expansion, and controlling chemical durability. The fact that simple borate glasses have rather high thermal expansion and low chemical durability attests to the unique influence of boron oxide additions upon the properties of silicate glasses. However, the impact of boron oxide additions upon surface properties of multicomponent borosilicates such as adsorption and reactivity is not yet well understood. In particular, the presence of multiple coordination states for boron is expected to introduce adsorption sites with different acidic or basic behavior, but their existence is yet unproven. To investigate these effects, multicomponent sodium aluminosilicate glasses have been prepared with varying sodium and boron concentrations and drawn into moderately high-surface-area continuous filament fibers. A relatively new technique, boron K-edge Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy is applied to study the local boron coordination at fracture and melt-derived fiber surfaces of these glasses. This structural information is combined with surface compositional information by X-ray Photoelectron Spectroscopy (XPS) to characterize the local atomic structure of boron at the as-formed glass surface. Finally, this information is used to interpret the adsorptivity of these as-formed and leached surfaces toward short-chain alcohol molecules through a new Inverse Gas Chromatography---Temperature Programmed Desorption (IGC-TPD) experiment. The results clearly show that boron additions to alkali-free glass surfaces introduce a unique adsorption site which is not present on boron-free glass surfaces and is easily removed by leaching in acidic solutions.

  7. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C.; Morgan, Michael J.

    1986-02-04

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

  8. 29Si NMR study of structural ordering in aluminosilicate geopolymer gels.

    PubMed

    Duxson, Peter; Provis, John L; Lukey, Grant C; Separovic, Frances; van Deventer, Jannie S J

    2005-03-29

    A systematic series of aluminosilicate geopolymer gels was synthesized and then analyzed using 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) in combination with Gaussian peak deconvolution to characterize the short-range ordering in terms of T-O-T bonds (where T is Al or Si). The effect of nominal Na2O/(Na2O + K2O) and Si/Al ratios on short-range network ordering was quantified by deconvolution of the 29Si MAS NMR spectra into individual Gaussian peaks representing different Q4(mAl) silicon centers. The deconvolution procedure developed in this work is applicable to other aluminosilicate gel systems. The short-range ordering observed here indicates that Loewenstein's Rule of perfect aluminum avoidance may not apply strictly to geopolymeric gels, although further analyses are required to quantify the degree of aluminum avoidance. Potassium geopolymers appeared to exhibit a more random Si/Al distribution compared to that of mixed-alkali and sodium systems. This work provides a quantitative account of the silicon and aluminum ordering in geopolymers, which is essential for extending our understanding of the mechanical strength, chemical and thermal stability, and fundamental structure of these systems.

  9. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

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

    1986-01-01

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

  10. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

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

    1985-07-10

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

  11. Milk-alkali syndrome

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000332.htm Milk-alkali syndrome To use the sharing features on this page, please enable JavaScript. Milk-alkali syndrome is a condition in which there ...

  12. Use of precalciners to remove alkali from raw materials in the cement industry. Final report, July 1978-July 1980

    SciTech Connect

    Gartner, E.M.

    1980-07-01

    The objective of this work was to develop an efficient means of removing alkali metal compounds (alkalies) from high-alkali aluminosilicate raw materials of the type commonly used as part of cement raw mixes in order to increase the energy efficiency of cement manufacture. The intention of this project was to determine whether the high-alkali raw materials could be pyroprocessed separately to remove the alkalies before they entered the rotary kiln, where they would be mixed with the other raw feed components. If this could be achieved, considerable savings could be made in the energy required to remove alkalies, compared to conventional methods in which the cement raw mix must be treated as a whole. Two different methods of alkali removal were examined, namely, vaporization of alkalies at relatively low temperatures; and alkali-rich melt separation at relativey high temperatures. The results showed that the removal of alkalies by pyroprocessing of high-alkali raw feed components separate from the other cement raw mix components is not likely to be a practical alternative to the best available conventional precalciner technology. (LCL)

  13. Alkali metal cation doped Al-SBA-15 for carbon dioxide adsorption.

    PubMed

    Zukal, Arnošt; Mayerová, Jana; Čejka, Jiří

    2010-01-01

    Mesoporous aluminosilicate adsorbents for carbon dioxide were prepared by the grafting of aluminium into SBA-15 silica using an aqueous solution of aluminium chlorohydrate. As the ion exchange sites are primarily associated with the presence of tetrahedrally coordinated aluminium, extra-framework aluminium on the SBA-15 surface was inserted into the silica matrix by a treatment with an aqueous solution of NH(4)OH. Synthesized mesoporous aluminosilicate preserving all the characteristic features of a mesoporous molecular sieve was finally modified by the alkali metal cation exchange. To examine carbon dioxide adsorption on prepared materials, adsorption isotherms in the temperature range from 0 °C to 60 °C were measured. Based on the known temperature dependence of adsorption isotherms, isosteric adsorption heats giving information on the surface energetics of CO(2) adsorption were calculated and discussed. The comparison of carbon dioxide isotherms obtained on aluminosilicate SBA-15, aluminosilicate SBA-15 containing cations Na(+) and K(+) and activated alumina F-200 reveals that the doping with sodium or potassium cations dramatically enhances adsorption in the region of equilibrium pressures lower than 10 kPa. Therefore, synthesized aluminosilicate adsorbents doped with Na(+) or K(+) cations are suitable for carbon dioxide separation from dilute gas mixtures.

  14. Characterization of Uranium Solids Precipitated with Aluminosilicates

    SciTech Connect

    DUFF, MC

    2004-04-29

    At the Savannah River Site (SRS), the High-Level Waste (HLW) Tank Farms store and process high-level liquid radioactive wastes from the Canyons and recycle water from the Defense Waste Processing Facility. The waste is concentrated using evaporators to minimize the volume of space required for HLW storage. Recently, the 2H Evaporator was shutdown due to the crystallization of sodium aluminosilicate (NAS) solids (such as cancrinite and sodalite) that contained close to 10 weight percent of elementally-enriched uranium (U). Prior to extensive cleaning,the evaporator deposits resided on the evaporator walls and other exposed internal surfaces within the evaporator pot. Our goal is to support the basis for the continued safe operation of SRS evaporators and to gain more information that could be used to help mitigate U accumulation during evaporator operation.

  15. Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

    NASA Astrophysics Data System (ADS)

    Tossell, J. A.

    1995-04-01

    13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

  16. Evaluation of the Incorporation of Uranium into Sodium Aluminosilicate Phases

    SciTech Connect

    Oji, L.N.

    2003-03-26

    This report describes batch laboratory experiments performed to determine the relative amounts of uranium incorporated in aluminosilicate structures during synthesis. The findings summarized here are based on laboratory experiments, which involved the synthesis of sodium aluminosilicates (NAS) structures, amorphous, zeolites A and sodalite phases in the presence of depleted uranium and the analytical search for incorporated uranium in NAS internal structures after synthesis. These studies will support the basis for continued operation of evaporators at the Savannah River Site (SRS).

  17. Investigation of aluminosilicate refractory for solid oxide fuel cell applications

    NASA Astrophysics Data System (ADS)

    Gentile, Paul Steven

    Stationary solid oxide fuel cells (SOFCs) have been demonstrated to provide clean and reliable electricity through electro-chemical conversion of various fuel sources (CH4 and other light hydrocarbons). To become a competitive conversion technology the costs of SOFCs must be reduced to less than $400/kW. Aluminosilicate represents a potential low cost alternative to high purity alumina for SOFC refractory applications. The objectives of this investigation are to: (1) study changes of aluminosilicate chemistry and morphology under SOFC conditions, (2) identify volatile silicon species released by aluminosilicates, (3) identify the mechanisms of aluminosilicate vapor deposition on SOFC materials, and (4) determine the effects of aluminosilicate vapors on SOFC electrochemical performance. It is shown thermodynamically and empirically that low cost aluminosilicate refractory remains chemically and thermally unstable under SOFC operating conditions between 800°C and 1000°C. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) of the aluminosilicate bulk and surface identified increased concentrations of silicon at the surface after exposure to SOFC gases at 1000°C for 100 hours. The presence of water vapor accelerated surface diffusion of silicon, creating a more uniform distribution. Thermodynamic equilibrium modeling showed aluminosilicate remains stable in dry air, but the introduction of water vapor indicative of actual SOFC gas streams creates low temperature (<1000°C) silicon instability due to the release of Si(OH)4 and SiO(OH) 2. Thermal gravimetric analysis and transpiration studies identified a discrete drop in the rate of silicon volatility before reaching steady state conditions after 100-200 hours. Electron microscopy observed the preferential deposition of vapors released from aluminosilicate on yttria stabilized zirconia (YSZ) over nickel. The adsorbent consisted of alumina rich clusters enclosed in an amorphous siliceous

  18. Characterization of Uranium Solids Precipitated with Aluminosilicates

    SciTech Connect

    DUFF, MC

    2004-01-09

    At the Savannah River Site (SRS), the High-Level Waste (HLW) Tank Farms store and process high-level liquid radioactive wastes from the Canyons and recycle water from the Defense Waste Processing Facility. The waste is concentrated using evaporators to minimize the volume of space required for HLW storage. Recently, the 2H Evaporator was shutdown due to the crystallization of sodium aluminosilicate (NAS) solids (such as cancrinite and sodalite) that contained close to 10 weight percent of elementally-enriched uranium (U). Prior to extensive cleaning,the evaporator deposits resided on the evaporator walls and other exposed internal surfaces within the evaporator pot. Our goal is to support the basis for the continued safe operation of SRS evaporators and to gain more information that could be used to help mitigate U accumulation during evaporator operation. To learn more about the interaction between U(VI) and NAS in HLW salt solutions, we performed several fundamental studies to examine the mechanisms of U accumulation with NAS in highly caustic solutions. This larger group of studies focused on the following processes: co-precipitation/structural incorporation, sorption, and precipitation (with or without NAS), which will be reviewed in this presentation. We will present and discuss local atomic structural characterization data about U that has been co-precipitated with NAS solids (such as amorphous zeolite precursor material and sodalite) using X-ray absorption fine-structure (XAFS) spectroscopic techniques.

  19. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-04-29

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  20. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2013-12-17

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  1. Densification mechanisms of haplogranite glasses as a function of water content and pressure based on density and Raman data

    NASA Astrophysics Data System (ADS)

    Ardia, P.; Di Muro, A.; Giordano, D.; Massare, D.; Sanchez-Valle, C.; Schmidt, M. W.

    2014-08-01

    This study investigates the effect of pressure (1 atm-2.5 GPa) and water (0.15, 2.7, 3.6 and 5.2 wt% H2O) on the network structure of alkali-rich alumino-silicate glasses synthesized at 1000 °C. Density increases linearly with pressure in the water-poor composition, while in the water-rich glasses and above 1.5 GPa densification decreases with pressure. Raman data suggest that several structural changes follow one upon another with increasing pressure and water content. The almost dry glasses undergo large modifications of the network ring structure with pressure, namely a decrease in average T-O-T angle, change in ring size statistics and possibly an increasingly homogeneous distribution of Al- and Si-rich domains at high pressure. Water dissolution favors a homogenization of ring sizes at low pressures. Pressure essentially induces a decrease in the average intertetrahedral angle and, above 1.5 GPa, a possible redistribution of Al/Si-rich regions. Pressure induces an increase in O-H bonding but decreases the O-H bond strength. The observed structural modifications are consistent with the decreasing net effect of pressure on viscosity as temperature and water increase through variation of the activation volume of viscosity.

  2. Spectroscopic studies of aluminosilicate formation in tank waste simulants

    SciTech Connect

    Su, Y.; Wang, L.; Bunker, B.C.; Windisch, C.F.

    1997-12-31

    Aluminosilicates are one of the major class of species controlling the volume of radioactive high-level waste that will be produced from future remediation at Hanford site. Here the authors present studies of the phases and structures of aluminosilicates as a function of sludge composition using X-ray powder diffraction, solid state {sup 27}Al and {sup 29}Si NMR, and Raman spectroscopy. The results show that the content of NaNO{sub 3} in solution has significant effects on the nature of the insoluble aluminosilicate phases produced. It was found that regardless of the initial Si:Al ratio, nitrate cancrinite was the main phase formed in the solution with pH of 13.5 and 5 M NaNO{sub 3}. However, at lower NaNO{sub 3} concentration with initial Si:Al ratios of 1.1, 2.2, and 11.0 in the solutions, a range of aluminosilicate zeolites was produced with Si:Al ratios of 1.1, 1.3, and 1.5, respectively. Lowering the solution pH appears to promote the formation of amorphous aluminosilicates. The results presented here are important for the prediction of the solubility and dissolution rate of Al in tank wastes.

  3. Secondary Waste Form Screening Test Results—Cast Stone and Alkali Alumino-Silicate Geopolymer

    SciTech Connect

    Pierce, Eric M.; Cantrell, Kirk J.; Westsik, Joseph H.; Parker, Kent E.; Um, Wooyong; Valenta, Michelle M.; Serne, R. Jeffrey

    2010-06-28

    PNNL is conducting screening tests on the candidate waste forms to provide a basis for comparison and to resolve the formulation and data needs identified in the literature review. This report documents the screening test results on the Cast Stone cementitious waste form and the Geopolymer waste form. Test results suggest that both the Cast Stone and Geopolymer appear to be viable waste forms for the solidification of the secondary liquid wastes to be treated in the ETF. The diffusivity for technetium from the Cast Stone monoliths was in the range of 1.2 × 10-11 to 2.3 × 10-13 cm2/s during the 63 days of testing. The diffusivity for technetium from the Geopolymer was in the range of 1.7 × 10-10 to 3.8 × 10-12 cm2/s through the 63 days of the test. These values compare with a target of 1 × 10-9 cm2/s or less. The Geopolymer continues to show some fabrication issues with the diffusivities ranging from 1.7 × 10-10 to 3.8 × 10-12 cm2/s for the better-performing batch to from 1.2 × 10-9 to 1.8 × 10-11 cm2/s for the poorer-performing batch. In the future more comprehensive and longer term performance testing will be conducted, to further evaluate whether or not these waste forms will meet the regulation and performance criteria needed to cost-effectively dispose of secondary wastes.

  4. The effect of TiO2/aluminosilicate nanocomposite additives on the mechanical and thermal properties of polyacrylic coatings

    NASA Astrophysics Data System (ADS)

    Nosrati, Rahimeh; Olad, Ali

    2015-12-01

    The commercial grade polyacrylic latex was modified in order to prepare a mechanical and thermal improved coating. TiO2/Ag-exchanged-aluminosilicate nanocomposites with montmorillonite, zeolite-A and clinoptilolite aluminosilicates were prepared and used as additive in the matrix of polyacrylic latex to achieve a coating with proper mechanical and thermal properties. X-ray diffraction patterns and FESEM were used to characterize the composition, structure, and morphology of the nanocomposite additives. Polyacrylic coatings modified by TiO2/Ag-exchanged-aluminosilicate nanocomposite additives showed higher adhesion strength and hardness compared to unmodified commercial grade polyacrylic coatings. Differential Scanning Calorimetry (DSC) analysis showed lower glass transition temperature for modified polyacrylic coatings than that of unmodified polyacrylic coatings. The tensile tests were also carried out for unmodified and modified polyacrylic coatings. According to the results, the modified polyacrylic based coating with TiO2/Ag-exchanged-clinoptilolite nanocomposite additive was the best coating considering most of useful properties.

  5. Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements.

    PubMed

    Shi, Caijun; Fernández-Jiménez, A

    2006-10-11

    This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (CSH) with low Ca/Si ratios or aluminosilicate gel at room temperature; CSH, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH)(2) and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement.

  6. Channel waveguides in glass via silver-sodium field-assisted ion exchange

    NASA Technical Reports Server (NTRS)

    Forrest, K.; Pagano, S. J.; Viehmann, W.

    1986-01-01

    Multimode channel waveguides have been formed in sodium aluminosilicate glass by field-assisted diffusion of Ag(+) ions from vacuum-evaporated Ag films. The two-dimensional refractive index profiles of the waveguides were controlled by varying the diffusion time, the diffusion temperature, and the electric field strength. Estimates of the diffusion rate through a strip aperture were obtained, assuming the electric field was strong 120-240 V/mm. The maximum change in refractive index in the sodium aluminosilicate glasses was estimated near 65 percent of the change in soda-lime silicate glass. The physical properties of the glasses are given in a table.

  7. Summary of research on the effect of LiNO{sub 3} on alkali-silica reaction in new concrete

    SciTech Connect

    Feng, X.; Thomas, M.D.A.; Bremner, T.W.; Folliard, K.J.; Fournier, B.

    2010-04-15

    This paper summarizes findings from a research study conducted at the University of New Brunswick in collaboration with the University of Texas at Austin, and CANMET-MTL, on the effect of LiNO{sub 3} on ASR in new concrete. The studies included expansion testing, silica dissolution measurements and microstructural examinations of cement systems containing glass and two different reactive aggregates (NB and NS). Only a small proportion of the data are presented here for the purpose of highlighting the principal findings of this investigation. Based on these findings, it is proposed that the inhibiting effect of LiNO{sub 3} against ASR in new concrete is attributed to the formation of two reaction products in the presence of lithium, these being a crystalline lithium silicate compound (Li{sub 2}SiO{sub 3}) crystal and a Li-bearing, low Ca silica gel. These two phases could serve as a diffusion barrier and protective layer to prevent the reactive silica from further attack by alkalis. It was found that the reason the two reactive aggregates selected responded differently to LiNO{sub 3} was due to the difference in their textural features. The NB aggregate contained reactive volcanic glass particles, the surface of which was immediately and equally available to sodium, potassium and lithium, and thus a Li-Si barrier was able to form quickly. The reactive phase in the NS aggregate was microcrystalline and strained quartz, which was embedded in a dense matrix of a non-reactive predominantly alumino-silicate phase and was not easily accessible to lithium.

  8. Synthesis and characterization of aluminosilicate catalyst impregnated by nickel oxide

    NASA Astrophysics Data System (ADS)

    Maulida, Iffana Dani; Sriatun, Taslimah

    2015-09-01

    Aluminosilicate as a catalyst has been synthesized by pore-engineering using CetylTrimethylAmmonium-Bromide (CTAB) as templating agent. It can produce bigger aluminosilicate pore therefore it will be more suitable for bulky molecule. The aims of this research are to synthesize aluminosilicate supported by Nickel, using CTAB surfactant as templating agent for larger pore radius than natural zeolite and characterize the synthesis product, consist of total acid sites and surface area characteristic. This research has been done with following steps. First, making sodium silicate and sodium aluminate. Second, aluminosilicate was synthesized by direct methods, calcined at 550, 650 and 750°C variation temperature, characterized product by X-RD and FTIR spectrometer. Third, NiCl2 was impregnated to the aluminosilicate that has the best cristallinity and main TO4 functional groups product (550 sample). Variation of NiCl2:aluminosilicate (w/w) ratio were 25%:75%, 50%:50% and 75%:25%. Last but not least characterization of catalytic properties was performed. It comprised total acidity test (gravimetric method) and Surface Area Analyzer. The result shows that the product synthesized by direct method at 550oC calcination temperature has the best cristallinity and main functional groups of TO4. The highest total acid sites was 31.6 mmole/g (Imp-A sample). Surface Area Analyzer shows that Imp-B sample has the best pore distribution and highest total pore volume and specific surface area with value 32.424 cc/g and 46.8287 m2/g respectively. We can draw the conclusion that the most potential catalyst is Imp-A sample compared to Imp-B and Imp-C because it has the highest total acid sites. However the most effective catalyst used for product selectivity was Imp-B sample among all samples.

  9. Boron Nitride Nanotubes-Reinforced Glass Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam; Hurst, Janet B.; Choi, Sung R.

    2005-01-01

    Boron nitride nanotubes of significant lengths were synthesized by reaction of boron with nitrogen. Barium calcium aluminosilicate glass composites reinforced with 4 weight percent of BN nanotubes were fabricated by hot pressing. Ambient-temperature flexure strength and fracture toughness of the glass-BN nanotube composites were determined. The strength and fracture toughness of the composite were higher by as much as 90 and 35 percent, respectively, than those of the unreinforced glass. Microscopic examination of the composite fracture surfaces showed pullout of the BN nanotubes. The preliminary results on the processing and improvement in mechanical properties of BN nanotube reinforced glass matrix composites are being reported here for the first time.

  10. Removal of ammonia from poultry manure by aluminosilicates.

    PubMed

    Wlazło, Łukasz; Nowakowicz-Dębek, Bożena; Kapica, Jacek; Kwiecień, Małgorzata; Pawlak, Halina

    2016-12-01

    The aim of the study was to test the possibility of using aluminosilicates as natural sorbents of ammonia from poultry manure. The ammonia-absorbing properties of sodium bentonite and zeolite were confirmed in ex situ conditions. The most significant reduction in the level of ammonia with respect to the control was noted for 2% bentonite and 1% zeolite. The mean reduction for the entire period of the experiment ranged from 26.41% to 29.04%. The aluminosilicates tested can be used to neutralize ammonia released on poultry farms.

  11. Recycling of aluminosilicate waste: Impact onto geopolymer formation

    NASA Astrophysics Data System (ADS)

    Essaidi, N.; Gharzouni, A.; Vidal, L.; Gouny, F.; Joussein, E.; Rossignol, S.

    2015-07-01

    Geopolymers are innovative ecomaterials resulting from the activation of an aluminosilicate source by an alkaline solution. Their properties depend on the used raw materials. This paper focuses on the possibility to obtain geopolymer materials with aluminosilicate laboratory waste. The effect of these additions on the geopolymer properties was studied by FTIR spectroscopy and mechanical test. It was evidenced a slowdown of the polycondensation reaction as well as the compressive strength due to the addition of laboratory waste which decreases the Si/K ratio of mixture.

  12. Effect of the alkali metal activator on the properties of fly ash-based geopolymers

    SciTech Connect

    Jaarsveld, J.G.S. van; Deventer, J.S.J. van

    1999-10-01

    The alkali and alkali earth metal cations present during the formation of most known aluminosilicate structures have a very significant effect on both the physical and chemical properties of the final product. Geopolymers are no exception, although this effect has not been thoroughly quantified and in the case of waste-based geopolymers it has not received any significant attention. The present study investigates the effect of mainly Na{sup +} and K{sup +} on the physical and chemical properties of fly ash-based geopolymeric binders both before and after setting has occurred. A variety of tests were conducted, including rheological measurements, various leaching tests, compressive strength testing, specific surface area determinations, and infrared spectroscopy (IR). It is concluded that the alkali metal cation controls and affects almost all stages of geopolymerization, from the ordering of ions and soluble species during the dissolution process to playing a structure-directing role during gel hardening and eventual crystal formation.

  13. Evaluation of High Permittivity Glass Ceramics for Millimeter Wave Applications.

    DTIC Science & Technology

    2014-09-26

    Millimeter Wave IfS ASTNACT (enew em reverse e* if n aesee7 wd Identify by block namber) - The crystallization and dielectric properties of strontium ...34Dielectric Properties of Strontium Titanate Glass Ceramics," is included in Appendix 3. ’- 5.0 PARTICIPATING SCIENTIFIC PERSONNEL Work on the contract was...OH, U.S.A Abstract Strontium titanate glass-ceramics, prepared by the crystallization of strontium titanate-aluminosilicate glasses have been

  14. Heterostructured layered aluminosilicate-itraconazole nanohybrid for drug delivery system.

    PubMed

    Yang, Jae-Hun; Jung, Hyun; Kim, Su Yeon; Yo, Chul Hyun; Choy, Jin-Ho

    2013-11-01

    A nanohybrid, consisting of layered aluminosilicate as a host material and itraconazole as a guest molecule, was successfully synthesized through the interfacial intercalation reaction across the boundary between water and water-immiscible liquid at the various pH. According to the powder X-ray diffraction pattern, the basal spacing of the intraconazole-layered aluminosilicate nanohybrid increased from 14.7 to 22.7 A depending on the pH of the aqueous suspension. The total amounts of itraconazole in the hybrids were determined to be 2.3-25.4 wt% by HPLC analysis. The in vivo pharmacokinetics study was performed in rats in order to compare the absorptions of itraconazole for the itraconazole-layered aluminosilicate nanohybrid and a commercial product, Sporanox. The pharmacokinetic data for the nanohybrid and Sporanox showed that the mean area under the plasma concentration-time curve (AUC, 2477 +/- 898 ng x hr/mL and 2630 +/- 953 ng x hr/mL, respectively) and maximum concentration (Cmax, 225.4 +/- 77.4 ng x hr/mL and 223.6 +/- 51.9 ng x hr/mL, respectively), were within the bioequivalence (BE) range. Therefore, we concluded that this drug-layered aluminosilicate nanohybrid system has a great potential for its application in formulation of poorly soluble drugs.

  15. A particulate isotopic standard of plutonium in an aluminosilicate matrix

    SciTech Connect

    Stoffels, J.J.; Cannon, W.C.; Robertson, D.M. )

    1991-01-01

    Plutonium isotopic microstandard particles have been produced for mass spectrometer calibration. The particles may also be useful as an elemental standard for calibration of electron and ion microprobe instruments. The standard consists of spherical, micrometer-size aluminosilicate particles loaded with plutonium of known isotopic distribution. The morphology, elemental composition, and plutonium isotopic composition of the particles have been characterized.

  16. Sodium Aluminosilicate Formation in Tank 43H Simulants

    SciTech Connect

    Wilmarth, W.R.; Walker, D.D.; Fink, S.D.

    1997-11-01

    This work studied the formation of a sodium aluminosilicate, Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}(NO{sub 3}){sub 2?4}H{sub 2}O, at 40{degree} 110{degree} C in simulated waste solutions with varied amounts of silicon and aluminum. The data agree well with literature solubility data for sodalite, the analogous chloride salt. The following conclusions result from this work: (1) The study shows, by calculation and experiments, that evaporation of the September 1997 Tank 43H inventory will only form minor quantities of the aluminosilicate. (2) The data indicate that the rate of formation of the nitrate enclathrated sodalite solid at these temperatures falls within the residence time ({lt}; 4 h) of liquid in the evaporator. (3) The silicon in entrained Frit 200 transferred to the evaporator with the Tank 43H salt solution will quantitatively convert to the sodium aluminosilicate. One kilogram of Frit 200 produces 2.1 kg of the sodium aluminosilicate.

  17. Alkali metal ionization detector

    DOEpatents

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

    1978-01-01

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

  18. Replacement of glass in the Nakhla meteorite by berthierine: Implications for understanding the origins of aluminum-rich phyllosilicates on Mars

    NASA Astrophysics Data System (ADS)

    Lee, Martin R.; Chatzitheodoridis, Elias

    2016-09-01

    A scanning and transmission electron microscope study of aluminosilicate glasses within melt inclusions from the Martian meteorite Nakhla shows that they have been replaced by berthierine, an aluminum-iron serpentine mineral. This alteration reaction was mediated by liquid water that gained access to the glasses along fractures within enclosing augite and olivine grains. Water/rock ratios were low, and the aqueous solutions were circumneutral and reducing. They introduced magnesium and iron that were sourced from the dissolution of olivine, and exported alkalis. Berthierine was identified using X-ray microanalysis and electron diffraction. It is restricted in its occurrence to parts of the melt inclusions that were formerly glass, thus showing that under the ambient physico-chemical conditions, the mobility of aluminum and silicon were low. This discovery of serpentine adds to the suite of postmagmatic hydrous silicates in Nakhla that include saponite and opal-A. Such a variety of secondary silicates indicates that during aqueous alteration compositionally distinct microenvironments developed on sub-millimeter length scales. The scarcity of berthierine in Nakhla is consistent with results from orbital remote sensing of the Martian crust showing very low abundances of aluminum-rich phyllosilicates.

  19. Solid oxide fuel cell having a glass composite seal

    DOEpatents

    De Rose, Anthony J.; Mukerjee, Subhasish; Haltiner, Jr., Karl Jacob

    2013-04-16

    A solid oxide fuel cell stack having a plurality of cassettes and a glass composite seal disposed between the sealing surfaces of adjacent cassettes, thereby joining the cassettes and providing a hermetic seal therebetween. The glass composite seal includes an alkaline earth aluminosilicate (AEAS) glass disposed about a viscous glass such that the AEAS glass retains the viscous glass in a predetermined position between the first and second sealing surfaces. The AEAS glass provides geometric stability to the glass composite seal to maintain the proper distance between the adjacent cassettes while the viscous glass provides for a compliant and self-healing seal. The glass composite seal may include fibers, powders, and/or beads of zirconium oxide, aluminum oxide, yttria-stabilized zirconia (YSZ), or mixtures thereof, to enhance the desirable properties of the glass composite seal.

  20. Structure and mechanical properties of aluminosilicate geopolymer composites with Portland cement and its constituent minerals

    SciTech Connect

    Tailby, Jonathan; MacKenzie, Kenneth J.D.

    2010-05-15

    The compressive strengths and structures of composites of aluminosilicate geopolymer with the synthetic cement minerals C{sub 3}S, beta-C{sub 2}S, C{sub 3}A and commercial OPC were investigated. All the composites showed lower strengths than the geopolymer and OPC paste alone. X-ray diffraction, {sup 29}Si and {sup 27}Al MAS NMR and SEM/EDS observations indicate that hydration of the cement minerals and OPC is hindered in the presence of geopolymer, even though sufficient water was present in the mix for hydration to occur. In the absence of SEM evidence for the formation of an impervious layer around the cement mineral grains, the poor strength development is suggested to be due to the retarded development of C-S-H because of the preferential removal from the system of available Si because geopolymer formation is more rapid than the hydration of the cement minerals. This possibility is supported by experiments in which the rate of geopolymer formation is retarded by the substitution of potassium for sodium, by the reduction of the alkali content of the geopolymer paste or by the addition of borate. In all these cases the strength of the OPC-geopolymer composite was increased, particularly by the combination of the borate additive with the potassium geopolymer, producing an OPC-geopolymer composite stronger than hydrated OPC paste alone.

  1. Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates

    SciTech Connect

    Ruiz-Santaquiteria, C.; Fernandez-Jimenez, A.; Palomo, A.

    2012-09-15

    This study investigates the effect of the alkaline solution/binder (S/B) ratio on the composition and nanostructure of the reaction products generated in the alkaline activation of aluminosilicates. The experiments used two mixtures of fly ash and dehydroxylated white clay and for each of these, varying proportions of the solution components. The alkali activator was an 8 M NaOH solution (with and without sodium silicate) used at three S/B ratios: 0.50, 0.75 and 1.25. The {sup 29}Si, {sup 27}Al MAS NMR and XRD characterisation of the reaction products reveal that for ratios nearest the value delivering suitable paste workability, the reaction-product composition and structure depend primarily on the nature and composition of the starting materials and the alkaline activator used. However, when an excess alkaline activator is present in the system, the reaction products tend to exhibit SiO{sub 2}/Al{sub 2}O{sub 3} ratios of approximately 1, irrespective of the composition of the starting binder or the alkaline activator.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  3. Analysis of early medieval glass beads - Glass in the transition period

    NASA Astrophysics Data System (ADS)

    Šmit, Žiga; Knific, Timotej; Jezeršek, David; Istenič, Janka

    2012-05-01

    Glass beads from graves excavated in Slovenia and dated archaeologically to the 7th-10th century AD were analysed by the combined PIXE-PIGE method. The results indicate two groups of glass; natron glass made in the Roman tradition and glass made with alkalis from the ash of halophytic plants, which gradually replaced natron glass after c. 800 AD. The alkalis used in the second group of glass seem to be in close relation to a variant of the Venetian white glass that appeared several centuries later. The origin of this glass may be traced to glass production in Mesopotamia and around the Aral Sea. All the mosaic beads with eye decoration, as well as most of the drawn-segmented and drawn-cut beads analysed, are of plant-ash glass, which confirms their supposed oriental origin.

  4. Recent developments in glass-ceramic materials

    SciTech Connect

    Beall, G.H.

    1993-12-31

    Glass-ceramic materials can be made by sintering and crystallization of fine glass powders or by internal nucleation and crystallization of formed glass articles. In both cases, the final properties are controlled by phase assemblage and microstructure. Transparent glass-ceramics based upon ultra-fine grained {beta}-quartz solid solution have been developed with near-zero thermal expansion coefficient for a variety of consumer and technical products: cookware, stove-tops, telescope mirrors, optical gyroscopes. Fluormica glass-ceramics with a {open_quotes}house-of-cards{close_quotes} microstructure are easily machined and have found wide application in vacuum systems, precision dielectric components, insulators, and medical and dental prostheses. Acicular chain silicate glass-ceramics are strong and tough, and have recently been developed as high performance tableware and magnetic memory disk substrates. Sintered glass-ceramics based on magnesium aluminosilicate frits are the basis of copper-cordierite packaging for advanced IC packaging.

  5. Glasses, ceramics, and composites from lunar materials

    NASA Technical Reports Server (NTRS)

    Beall, George H.

    1992-01-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

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

    NASA Technical Reports Server (NTRS)

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

    1966-01-01

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

  7. Effect of silicate modulus and metakaolin incorporation on the carbonation of alkali silicate-activated slags

    SciTech Connect

    Bernal, Susan A.; Mejia de Gutierrez, Ruby; Provis, John L.; Rose, Volker

    2010-06-15

    Accelerated carbonation is induced in pastes and mortars produced from alkali silicate-activated granulated blast furnace slag (GBFS)-metakaolin (MK) blends, by exposure to CO{sub 2}-rich gas atmospheres. Uncarbonated specimens show compressive strengths of up to 63 MPa after 28 days of curing when GBFS is used as the sole binder, and this decreases by 40-50% upon complete carbonation. The final strength of carbonated samples is largely independent of the extent of metakaolin incorporation up to 20%. Increasing the metakaolin content of the binder leads to a reduction in mechanical strength, more rapid carbonation, and an increase in capillary sorptivity. A higher susceptibility to carbonation is identified when activation is carried out with a lower solution modulus (SiO{sub 2}/Na{sub 2}O ratio) in metakaolin-free samples, but this trend is reversed when metakaolin is added due to the formation of secondary aluminosilicate phases. High-energy synchrotron X-ray diffractometry of uncarbonated paste samples shows that the main reaction products in alkali-activated GBFS/MK blends are C-S-H gels, and aluminosilicates with a zeolitic (gismondine) structure. The main crystalline carbonation products are calcite in all samples and trona only in samples containing no metakaolin, with carbonation taking place in the C-S-H gels of all samples, and involving the free Na{sup +} present in the pore solution of the metakaolin-free samples. Samples containing metakaolin do not appear to have the same availability of Na{sup +} for carbonation, indicating that this is more effectively bound in the presence of a secondary aluminosilicate gel phase. It is clear that claims of exceptional carbonation resistance in alkali-activated binders are not universally true, but by developing a fuller mechanistic understanding of this process, it will certainly be possible to improve performance in this area.

  8. Alkali metal ion battery with bimetallic electrode

    DOEpatents

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

    2015-04-07

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

  9. Ideas about Acids and Alkalis.

    ERIC Educational Resources Information Center

    Toplis, Rob

    1998-01-01

    Investigates students' ideas, conceptions, and misconceptions about acids and alkalis before and after a teaching sequence in a small-scale research project. Concludes that student understanding of acids and alkalis is lacking. (DDR)

  10. Amorphous and nanostructured silica and aluminosilicate spray-dried microspheres

    NASA Astrophysics Data System (ADS)

    Todea, M.; Turcu, R. V. F.; Frentiu, B.; Tamasan, M.; Mocuta, H.; Ponta, O.; Simon, S.

    2011-08-01

    Amorphous silica and aluminosilicate microspheres with diameters in the 0.1-20 μm range were produced by spray drying method. SEM, TEM and AFM images showed the spherical shape of the obtained particles. Based on thermal analysis data, several heat treatments have been applied on the as-prepared samples in order to check the amorphous state stability of the microspheres and to develop nanosized crystalline phases. As-prepared microspheres remain amorphous up to 1400 °C. By calcination at 1400 °C, cristobalite type nanocrystals are developed on silica sample, while in aluminosilicate sample first are developed mullite type nanocrystals and only after prolonged treatment are developed also cristobalite type nanocrystals. 29Si and 27Al MAS NMR results show that the local order around aluminum and silicon atoms strongly depend on the thermal history of the microspheres.

  11. XPS study of protein adsorption onto nanocrystalline aluminosilicate microparticles

    NASA Astrophysics Data System (ADS)

    Vanea, E.; Simon, V.

    2011-01-01

    X-ray photoelectron spectroscopy (XPS) was used to study the interaction of two different sized proteins, bovine serum albumin (BSA) and fibrinogen, with an aluminosilicate system containing yttrium and iron that is a potential biomaterial. Serum albumin and fibrinogen are two major plasma proteins and the most relevant proteins adsorbed on the surface of biomaterials in blood contact. The aluminosilicate samples were incubated for several exposure times, up to 24 h, in simulated body fluid enriched with BSA, and in buffered fibrinogen solution. Time dependence of proteins adsorption onto surface of the investigated samples is reflected by the evolution of the new N 1s photoelectron peak and by the modification of C 1s core-level spectra recorded from the samples immersed in protein solution.

  12. Methods of recovering alkali metals

    DOEpatents

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

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

  13. Chemical and mechanical consequences of environmental barrier coating exposure to calcium-magnesium-aluminosilicate.

    SciTech Connect

    Harder, B.; Ramirez-Rico, J.; Almer, J. D.; Kang, L.; Faber, K.

    2011-06-01

    The success of Si-based ceramics as high-temperature structural materials for gas turbine applications relies on the use of environmental barrier coatings (EBCs) with low silica activity, such as Ba{sub 1-x}Sr{sub x}Al{sub 2}Si{sub 2}O{sub 8} (BSAS), which protect the underlying components from oxidation and corrosion in combustion environments containing water vapor. One of the current challenges concerning EBC lifetime is the effect of sandy deposits of calcium-magnesium-aluminosilicate (CMAS) glass that melt during engine operation and react with the EBC, changing both its composition and stress state. In this work, we study the effect of CMAS exposure at 1300 C on the residual stress state and composition in BSAS-mullite-Si-SiC multilayers. Residual stresses were measured in BSAS multilayers exposed to CMAS for different times using high-energy X-ray diffraction. Their microstructure was studied using a combination of scanning electron microscopy and transmission electron microscopy techniques. Our results show that CMAS dissolves the BSAS topcoat preferentially through the grain boundaries, dislodging the grains and changing the residual stress state in the topcoat to a nonuniform and increasingly compressive stress state with increasing exposure time. The presence of CMAS accelerates the hexacelsian-to-celsian phase transformation kinetics in BSAS, which reacts with the glass by a solution-reprecipitation mechanism. Precipitates have crystallographic structures consistent with Ca-doped celsian and Ba-doped anorthite.

  14. Hard x-ray nanotomography of amorphous aluminosilicate cements.

    SciTech Connect

    Provis, J. L.; Rose, V.; Winarski, R. P.; van Deventer, J. S. J.

    2011-08-01

    Nanotomographic reconstruction of a sample of low-CO{sub 2} 'geopolymer' cement provides the first three-dimensional view of the pore structure of the aluminosilicate geopolymer gel, as well as evidence for direct binding of geopolymer gel onto unreacted fly ash precursor particles. This is central to understanding and optimizing the durability of concretes made using this new class of binder, and demonstrates the value of nanotomography in providing a three-dimensional view of nanoporous inorganic materials.

  15. Modeling the Viscosity of Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Decterov, Sergei A.; Grundy, A. Nicholas; Jung, In-Ho; Pelton, Arthur D.

    2007-12-01

    Silicate systems are of fundamental importance for many metallurgical processes, for the glass industry and also for many aspects of geology. In addition to the phase relations, there are many properties of the liquid phase such as molar volume, surface tension, absorption coefficient, thermal conductivity and viscosity that are important for understanding, simulating and modeling processes involving silicate liquids. Over the past several years, through critical evaluation of all available thermodynamic and phase equilibrium data, we have developed a quantitative thermodynamic description of multicomponent silicate melts using the Modified Quasichemical Model for short-range ordering. We find that the local structure of the liquid, in terms of the bridging behavior of oxygen, calculated using our thermodynamic description allows us to link the viscosity and the thermodynamics of the silicate liquid. We can thus simultaneously calculate phase relations, thermodynamics and viscosity of the liquid over a wide composition and temperature range. In the present work we outline the viscosity model using selected binary and ternary systems as examples. The model has successfully been applied to melts in the multicomponent Na2O-K2O-MgO-CaO-MnO-FeO-ZnO-PbO-Al2O3-SiO2 system and more elements are currently being added to the database.

  16. Chlor-Alkali Technology.

    ERIC Educational Resources Information Center

    Venkatesh, S.; Tilak, B. V.

    1983-01-01

    Chlor-alkali technology is one of the largest electrochemical industries in the world, the main products being chlorine and caustic soda (sodium hydroxide) generated simultaneously by the electrolysis of sodium chloride. This technology is reviewed in terms of electrochemical principles and manufacturing processes involved. (Author/JN)

  17. Hydrothermal alkali metal recovery process

    DOEpatents

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

    1980-01-01

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

  18. The Roles of Temperature and Composition in High-Pressure Structural Changes in Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Stebbins, J. F.

    2009-12-01

    Extensive recent NMR studies show large effects of composition on the extent of structural change in aluminosilicate glasses quenched from melts at high pressure, which correlate with observed, recovered density increases. Although such results will eventually need to be complemented by quantitative, in situ spectroscopic and scattering measurements, they already provide important constraints on the types of models necessary to capture the complexity of structure-property relationships for multicomponent natural magmas. For example, smaller and/or higher charged network modifier/charge compensator cations (e.g. Mg2+ vs. Ca2+, Ca2+ vs. K+) generally promote greater densification as well as increased conversion of four-coordinated to five- and six-coordinated Al (Al-27 NMR), but such effects may be non-linear in mixed-cation systems. At the same time, simple calculations with estimates of changes in partial molar volumes suggest that much of the observed density increases must be due to compression of “soft” sites in the structure and to the accompanying narrowing of inter-tetrahedral network bond angles (e.g. Si-O-Si). These can in turn be detected as reductions in mean Na-O distances (Na-23 NMR) and shifts in Si-29 spectra. As the field strength of the modifier cation increases farther (e.g. from Ca2+ to La3+), this pattern shifts: such “intermediate” cations can react to pressure increases by increasing their own coordinations and M-O distances (La K-edge XAS), reducing effects on network cation coordination. An extreme example of this can be seen as the Al/Si ratio changes: only at low Al contents are increases in Si coordination large enough to be detected by Si-29 NMR. Numerous recent studies of high-pressure glasses by O-17 NMR (e.g. S.K. Lee et al.) have emphasized the role of non-bridging oxygens (NBO) in increases of Si and Al coordination with pressure, as well as the critical importance of this species to melt properties. It is likely that

  19. Alkalis in alternative biofuels

    SciTech Connect

    Miles, T.R.; Miles, T.R. Jr.; Bryers, R.W.; Baxter, L.L.; Jenkins, B.M.; Oden, L.L.

    1994-12-31

    The alkali content and behavior of inorganic material of annually produced biofuels severely limits their use for generating electrical power in conventional furnaces. A recent eighteen-month investigation of the chemistry and firing characteristics of 26 different biofuels has been conducted. Firing conditions were simulated in the laboratory for eleven biofuels. This paper describes some results from the investigation including fuel properties, deposits, deposition mechanisms, and implications for biomass boiler design, fuel sampling and characterizations. Urban wood fuel, agricultural residues, energy crops, and other potential alternate fuels are included in the study. Conventional methods for establishing fuel alkali content and determining ash sticky temperatures were deceptive. The crux of the problem was found to be the high concentration of potassium in biofuels and its reactions with other fuel constituents which lower the ``sticky temperature`` of the ash to the 650 C to 760 C (1,200 F-1,400 F).

  20. Alkali-vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.; Krupke, W. F.

    2010-02-01

    We report on the results from several of our alkali laser systems. We show highly efficient performance from an alexandrite-pumped rubidium laser. Using a laser diode stack as a pump source, we demonstrate up to 145 W of average power from a CW system. We present a design for a transversely pumped demonstration system that will show all of the required laser physics for a high power system.

  1. Capture of alkali during pressurized fluidized-bed combustion using in-bed sorbents

    SciTech Connect

    Mann, M.D.; Ludlow, D.K.

    1997-12-31

    The primary focus of this research was the removal of alkali from PFBC flue gases to a level specified by turbine manufactures. The target level was less than 24 ppbw. Several of the aluminosilicate minerals have the potential to capture alkalis, especially sodium and potassium, under conditions typical of fluid-bed operation. Other goals of this work were to investigate the potential for simultaneously removing SO{sub 2} and Cl from the PFBC gas stream. The initial work focused primarily on one class of sorbents, sodalites, with the goal of determining whether sodalites can be used as an in-bed sorbent to simultaneously remove alkali and sulfur. Thermo gravimetric analysis (TGA) was used to study the mechanism of alkali capture using sodalite. Further testing was performed on a 7.6 cm (3-in.)-diameter pressurized fluid-bed reactor (PFBR). Early results indicated that simultaneous removal of alkali and sulfur and/or chlorine was not practical under the conditions for commercial PFBC operations. Therefore, the focus of the latter part of this work was on sorbents that have been shown to capture alkali in other systems. The effectiveness of bauxite and kaolinite to reduce vapor-phase alkali concentrations was determined. In addition to studying the gettering capability of the sorbent, the impact of the getter on operational performance was evaluated. This evaluation included examining potential agglomeration of bed particles, deposition on heat-transfer surfaces, and the bridging and blinding of ceramic candle filters. The focus of this paper is on the work performed on the PFBR.

  2. Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

    SciTech Connect

    Bernal, Susan A.; Provis, John L.; Walkley, Brant; San Nicolas, Rackel; Gehman, John D.; Brice, David G.; Kilcullen, Adam R.; Duxson, Peter; Deventer, Jannie S.J. van

    2013-11-15

    Binders formed through alkali-activation of slags and fly ashes, including ‘fly ash geopolymers’, provide appealing properties as binders for low-emissions concrete production. However, the changes in pH and pore solution chemistry induced during accelerated carbonation testing provide unrealistically low predictions of in-service carbonation resistance. The aluminosilicate gel remaining in an alkali-activated slag system after accelerated carbonation is highly polymerised, consistent with a decalcification mechanism, while fly ash-based binders mainly carbonate through precipitation of alkali salts (bicarbonates at elevated CO{sub 2} concentrations, or carbonates under natural exposure) from the pore solution, with little change in the binder gel identifiable by nuclear magnetic resonance spectroscopy. In activated fly ash/slag blends, two distinct gels (C–A–S–H and N–A–S–H) are formed; under accelerated carbonation, the N–A–S–H gel behaves comparably to fly ash-based systems, while the C–A–S–H gel is decalcified similarly to alkali-activated slag. This provides new scope for durability optimisation, and for developing appropriate testing methodologies. -- Highlights: •C-A-S-H gel in alkali-activated slag decalcifies during accelerated carbonation. •Alkali-activated fly ash gel changes much less under CO{sub 2} exposure. •Blended slag-fly ash binder contains two coexisting gel types. •These two gels respond differently to carbonation. •Understanding of carbonation mechanisms is essential in developing test methods.

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

    NASA Astrophysics Data System (ADS)

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

    1999-11-01

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

  4. A Novel Fluoride Route for the Synthesis of Aluminosilicate Nanotubes

    PubMed Central

    Chemmi, Atika; Brendlé, Jocelyne; Marichal, Claire; Lebeau, Bénédicte

    2013-01-01

    In this work we present a novel method for synthesis of aluminosilicate nanotubes: the fluoride route. F-containing imogolite (F-IMO) exhibits an improved crystallization rate and improved yield. The structure of F-IMO was investigated and compared with F-free imogolite (IMO) by means of X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR) confirming imogolite structure. Solid state nuclear magnetic resonance (NMR) analyses show an increased crystallization rate for F-IMO and confirm the incorporation of fluorine ion in the structure. PMID:28348325

  5. Characterisation of frequency doubling in Eu(2+) doped aluminosilicate fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    The results of a series of experiments on efficient second-harmonic generation in a fiber with a Eu(2+)-doped aluminosilicate core are reported. The fiber was prepared by the seeding method with CW mode-locked radiation at 1.06 micron and produced ultrastable peak conversion efficiencies of 0.001 during mode-locked readout. Experiments were performed to determine the IR preparation intensity dependence, the stability of the output, and the type of erasure mechanisms which occur. The results are compared with those of germanosilicate fibers and some similarities and differences are discussed.

  6. Experimental Modeling of Peridotite Melting with Alkali-Carbonate Fluid at P = 3.9 GPa, T=1250°C

    NASA Astrophysics Data System (ADS)

    Kostyuk, Anastasia; Gorbachev, Nikolay; Nekrasov, Alexey

    2014-05-01

    The close association of alkaline and ultramafic rocks with carbonatites, apatite and sulfide mineralization, as well as features of the melt compositions, tell us about the mantle source and the importance of alkaline-carbonate fluids in the genesis of these rocks. Experimental modeling of formation of alkali silicate, carbonate and sulfide melts was carried out in the system peridotite-alkaline-carbonate fluid (K, Na)2CO3 with additives of apatite, nickel-containing pyrrhotite, ilmenite and zircon as accessory minerals at P= 3.9 GPa and T=1250°C. Composition of coexisting melts, phase relationships, behavior of titanium, phosphorus, sulfur and zircon have been studied in this system. Liquidus association of phlogopite-clinopyroxene-zircon-X-phase (not diagnosed titanium and phosphorus-containing aluminosilicate phase) cemented by intergranular silicate glass with inclusions of carbonate and sulphide phases at partial (10%) melting of peridotite. Morphology, composition and relations of silicate glass, carbonate and sulfide globules indicate the existence of immiscible silicate, carbonate and sulfide melts at the experimental conditions. The composition of the silicate melt is phonolite, carbonate melt - significantly calcium composition with an admixture of alkali metal and silicate components. Solubility of zircon in silicate melt reached up to 0.8 wt.% of ZrO2, in coexisting carbonate melt - up to 1.5 wt.%. Absence of ilmenite and apatite in the experimental samples due to their high solubility in the coexisting phases. Concentration of TiO2 and P2O5 in silicate melt reached 2 wt. %. The concentration of TiO2 in the carbonate melt up to 1.7 wt.% and P2O5 up to 14 wt.%. The sulfur concentration in these melts does not exceed 0.2 wt.%. Concentrators of titanium and phosphorus among liquidus minerals were X-phase and phlogopite - 8 wt.% TiO2 and up to 3 wt.% P2O5 in the X-phase; up to 6 wt.% TiO2 and up to 2.5 wt.% of P2O5 in the phlogopite. The distribution

  7. Energetics of formation of alkali and ammonium cobalt and zinc phosphate frameworks

    SciTech Connect

    Le, So-Nhu; Navrotsky, Alexandra

    2008-01-15

    Alkali and ammonium cobalt and zinc phosphates show extensive polymorphism. Thermal behavior, relative stabilities, and enthalpies of formation of KCoPO{sub 4}, RbCoPO{sub 4}, NH{sub 4}CoPO{sub 4}, and NH{sub 4}ZnPO{sub 4} polymorphs are studied by differential scanning calorimetry, high-temperature oxide melt solution calorimetry, and acid solution calorimetry. {alpha}-KCoPO{sub 4} and {gamma}-KCoPO{sub 4} are very similar in enthalpy. {gamma}-KCoPO{sub 4} slowly transforms to {alpha}-KCoPO{sub 4} near 673 K. The high-temperature phase, {beta}-KCoPO{sub 4}, is 5-7 kJ mol{sup -1} higher in enthalpy than {alpha}-KCoPO{sub 4} and {gamma}-KCoPO{sub 4}. HEX phases of NH{sub 4}CoPO{sub 4} and NH{sub 4}ZnPO{sub 4} are about 3 kJ mol{sup -1} lower in enthalpy than the corresponding ABW phases. There is a strong relationship between enthalpy of formation from oxides and acid-base interaction for cobalt and zinc phosphates and also for aluminosilicates with related frameworks. Cobalt and zinc phosphates exhibit similar trends in enthalpies of formation from oxides as aluminosilicates, but their enthalpies of formation from oxides are more exothermic because of their stronger acid-base interactions. Enthalpies of formation from ammonia and oxides of NH{sub 4}CoPO{sub 4} and NH{sub 4}ZnPO{sub 4} are similar, reflecting the similar basicity of CoO and ZnO. - Graphical abstract: Relationship between enthalpy of formation from oxides and acid-base interaction for cobalt phosphates, zinc phosphates, and aluminosilicates with related frameworks. They exhibit similar trends, but the enthalpies of formation of phosphates are more exothermic than those of aluminosilicates because of stronger acid-base interactions.

  8. Sol-gel derived aluminosilicate coatings on alumina as substrate for osteoblasts.

    PubMed

    Leivo, Jarkko; Meretoja, Ville; Vippola, Minnamari; Levänen, Erkki; Vallittu, Pekka; Mäntylä, Tapio A

    2006-11-01

    Rat bone marrow stromal cell differentiation on aluminosilicate 3Al(2)O(3)-2SiO(2) coatings was investigated. Thin ceramic coatings were prepared on alpha-alumina substrates by the sol-gel process and calcined in order to establish an amorphous aluminosilicate ceramic phase with and without nanosized transitional mullite crystals. In addition, coatings of thermally sprayed aluminosilicate and diphasic gamma-alumina-silica nanosized colloids were prepared. Cell culture testing by rat osteoblasts showed good biocompatibility for aluminosilicates with sustained normal osteoblast functions. Despite mutual disparities in physical and chemical nanostructures, the culture findings suggested fairly similar osteoblast response to all tested coatings. The results suggest that topographical frequency parameters and chemical uniformity are important parameters in determining the best conditions for osteoblasts on sol-gel derived aluminosilicate materials.

  9. Viscous sealing glass compositions for solid oxide fuel cells

    SciTech Connect

    Kim, Cheol Woon; Brow, Richard K.

    2016-12-27

    A sealant for forming a seal between at least two solid oxide fuel cell components wherein the sealant comprises a glass material comprising B.sub.2O.sub.3 as a principal glass former, BaO, and other components and wherein the glass material is substantially alkali-free and contains less than 30% crystalline material.

  10. Surface structure and structural point defects of liquid and amorphous aluminosilicate nanoparticles

    NASA Astrophysics Data System (ADS)

    Linh, Nguyen Ngoc; Van Hoang, Vo

    2008-07-01

    The surface structure of liquid and amorphous aluminosilicate nanoparticles of composition Al2O3·2SiO2 has been investigated in a model of different sizes ranging from 2.0 to 5.0 nm with the Born-Mayer type pair potential under non-periodic boundary conditions. Models have been obtained by cooling from the melts at a constant density of 2.6 g cm-3 via molecular dynamics (MD) simulation. The surface structure has been investigated via the coordination number, bond-angle distributions and structural point defects. Calculations show that surface effects on surface static and thermodynamic properties of models are significant according to the change in the number of Al atoms in the surface layers. Evolution of the local environment of oxygen in the surface shell of nanoparticles upon cooling from the melt toward the glassy state was also found and discussed. In addition, the nanosize dependence of the glass transition temperature was presented.

  11. Effective Sequestration of Clostridium difficile Protein Toxins by Calcium Aluminosilicate

    PubMed Central

    Pokusaeva, Karina; Carpenter, Robert

    2015-01-01

    Clostridium difficile is a leading cause of antibiotic-associated diarrhea and the etiologic agent responsible for C. difficile infection. Toxin A (TcdA) and toxin B (TcdB) are nearly indispensable virulence factors for Clostridium difficile pathogenesis. Given the toxin-centric mechanism by which C. difficile pathogenesis occurs, the selective sequestration with neutralization of TcdA and TcdB by nonantibiotic agents represents a novel mode of action to prevent or treat C. difficile-associated disease. In this preclinical study, we used quantitative enzyme immunoassays to determine the extent by which a novel drug, calcium aluminosilicate uniform particle size nonswelling M-1 (CAS UPSN M-1), is capable of sequestering TcdA and TcdB in vitro. The following major findings were derived from the present study. First, we show that CAS UPSN M-1 efficiently sequestered both TcdA and TcdB to undetectable levels. Second, we show that CAS UPSN M-1's affinity for TcdA is greater than its affinity for TcdB. Last, we show that CAS UPSN M-1 exhibited limited binding affinity for nontarget proteins. Taken together, these results suggest that ingestion of calcium aluminosilicate might protect gastrointestinal tissues from antibiotic- or chemotherapy-induced C. difficile infection by neutralizing the cytotoxic and proinflammatory effects of luminal TcdA and TcdB. PMID:26149988

  12. Chlorine, in the Presence of Iron, Does Indeed Decrease the Viscosity of Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Webb, S. L.

    2012-12-01

    The effect of volatiles on melt rheology is investigated here, as the degassing of magma before an eruption usually leads to an increase in magma viscosity; and therefore increases the probability of an explosive eruption. There is not a large amount of data on the effect of chlorine on viscosity. It would appear, however, that chlorine increases the viscosity of peralkaline sodium-aluminosilicate melts, and decreases the viscosity of peraluminous sodium-aluminosilicate melts. These different effects of chlorine on viscosity indicate that the chlorine sits in different structural sites in peraluminous and peralkaline melts. In previous studies of rheology in this laboratory, we have shown that chlorine does indeed increase the viscosity of a phonolite analog Na2O-CaO-Al2O3-SiO2 melt. In this study, we have extended our investigation of the rheology of chlorine-bearing melts to basaltic compositions. The melt composition used here is that of a basaltic glass taken from the mid-Atlantic Ridge at 3000 m depth during the Venture Cruise (Ireland) of 2011. The viscosities were determined using the micropenetration technique in the 109-1012 Pa s range at temperatures 600-800 C. It was found that the addition of 0.6 wt% Cl resulted in a 0.5 log unit decrease in viscosity. A synthetic haplo-basaltic melt with the iron replaced by Mg and the Al was also synthesized. The addition of 0.3 wt% chlorine to this melt resulted in a 0.3 log unit increase in viscosity; as observed previously for Fe-free peralkaline melts. Based on these viscosity data it would appear that the effect of chlorine on rheology is a function of the composition of the melt, and that the structural site taken by chlorine varies as a function of the presence or absence of iron. The addition of chlorine to the iron-bearing melt, increased the Fe2+/Fetot from 0.30 to 0.45. This indicates that the presence of chlorine results in an energetic preference for Fe2+ in the melt structure. Thus, it is not so much the

  13. Preparation of alkali metal dispersions

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Landel, R. F. (Inventor)

    1968-01-01

    A method is described for producing alkali metal dispersions of high purity. The dispersions are prepared by varying the equilibrium solubility of the alkali metal in a suitable organic solvent in the presence of aromatic hydrocarbons. The equilibrium variation is produced by temperature change. The size of the particles is controlled by controlling the rate of temperature change.

  14. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

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

  15. Applications of high resolution NMR to geochemistry: crystalline, glass, and molten silicates

    SciTech Connect

    Schneider, E.

    1985-11-01

    The nuclear spin interactions and the associated quantum mechanical dynamics which are present in solid state NMR are introduced. A brief overview of aluminosilicate structure is presented and crystalline structure is then reviewed, with emphasis on the contributions made by /sup 29/Si NMR spectroscopy. The local structure of glass aluminosilicates as observed by NMR, is presented with analysis of the information content of /sup 29/Si spectra. A high-temperature (to 1300/sup 0/C) NMR spectroscopic investigation of the local environment and dynamics of molecular motion in molten aluminosilicates is described. A comparison is made of silicate liquid, glass, and crystalline local structure. The atomic and molecular motions present in a melt are investigated through relaxation time (T/sub 1/ and T/sub 2/) measurements as a function of composition and temperature for /sup 23/Na and /sup 29/Si.

  16. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

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

  17. Thin glass processing with various laser sources

    NASA Astrophysics Data System (ADS)

    Collins, Adam R.; Milne, David; Prieto, Camilo; O'Connor, Gerard M.

    2015-03-01

    Laser processing of thin glass has proven problematic due to the inefficient coupling of optical energy into glass and the difficulty achieving an economical processing speed while maintaining cut quality. Laser glass processing is pertinent to touch screen display, microfluidic, microoptic and photovoltaic applications. The results of the laser scribing of 110 μm thick alkali free glass with various laser sources are presented. The laser sources include a CO₂ laser, nanosecond UV laser and femtosecond IR laser. The contrasting absorption mechanisms are discussed. Cut quality and processing speed are characterised using SEM and optical microscopy techniques. Alternative laser techniques for thin glass processing are also considered.

  18. SODIUM ALUMINOSILICATE FOULING AND CLEANING OF DECONTAMINATED SALT SOLUTION COALESCERS

    SciTech Connect

    Poirier, M; Thomas Peters, T; Fernando Fondeur, F; Samuel Fink, S

    2008-10-28

    During initial non-radioactive operations at the Modular Caustic Side Solvent Extraction Unit (MCU), the pressure drop across the decontaminated salt solution coalescer reached {approx}10 psi while processing {approx}1250 gallons of salt solution, indicating possible fouling or plugging of the coalescer. An analysis of the feed solution and the 'plugged coalescer' concluded that the plugging was due to sodium aluminosilicate solids. MCU personnel requested Savannah River National Laboratory (SRNL) to investigate the formation of the sodium aluminosilicate solids (NAS) and the impact of the solids on the decontaminated salt solution coalescer. Researchers performed developmental testing of the cleaning protocols with a bench-scale coalescer container 1-inch long segments of a new coalescer element fouled using simulant solution. In addition, the authors obtained a 'plugged' Decontaminated Salt Solution coalescer from non-radioactive testing in the MCU and cleaned it according to the proposed cleaning procedure. Conclusions from this testing include the following: (1) Testing with the bench-scale coalescer showed an increase in pressure drop from solid particles, but the increase was not as large as observed at MCU. (2) Cleaning the bench-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (11 g of bayerite if all aluminum is present in that form or 23 g of sodium aluminosilicate if all silicon is present in that form). (3) Based on analysis of the cleaning solutions from bench-scale test, the 'dirt capacity' of a 40 inch coalescer for the NAS solids tested is calculated as 450-950 grams. (4) Cleaning the full-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (60 g of aluminum and 5 g of silicon). (5) Piping holdup in the full-scale coalescer system caused the pH to differ from the target value. Comparable hold-up in the facility could lead to less effective

  19. Ion-Exchange Interdiffusion Model with Potential Application to Long-Term Nuclear Waste Glass Performance

    SciTech Connect

    Neeway, James Joseph; Kerisit, Sebastien N.; Liu, Jia; Zhang, Jiandong; Zhu, Zihua; Riley, Brian Joseph; Ryan, Joseph Vincent

    2016-05-05

    Abstract: Ion exchange is an integral mechanism influencing the corrosion of glasses. Due to the formation of alteration layers in aqueous conditions, it is difficult to conclusively deconvolute the process of ion exchange from other processes, principally dissolution of the glass matrix. Therefore, we have developed a method to isolate alkali diffusion that involves contacting glass coupons with a solution of 6LiCl dissolved in functionally inert dimethyl sulfoxide. We employ the method at temperatures ranging from 25 to 150 °C with various glass formulations. Glass compositions include simulant nuclear waste glasses, such as SON68 and the international simple glass (ISG), glasses in which the nature of the alkali element was varied, and glasses that contained more than one alkali element. An interdiffusion model based on Fick’s second law was developed and applied to all experiments to extract diffusion coefficients. The model expands established models of interdiffusion to the case where multiple types of alkali sites are present in the glass. Activation energies for alkali ion exchange were calculated and the results are in agreement with those obtained in glass strengthening experiments but are nearly five times higher than values reported for diffusion-controlled processes in nuclear waste glass corrosion experiments. A discussion of the root causes for this apparent discrepancy is provided. The interdiffusion model derived from laboratory experiments is expected to be useful for modeling glass corrosion in a geological repository when the silicon concentration is high.

  20. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

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

    2016-08-02

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

  1. Predicting Large CO2 Adsorption in Aluminosilicate Zeolites for Postcombustion Carbon Dioxide Capture

    SciTech Connect

    Kim, J; Lin, LC; Swisher, JA; Haranczyk, M; Smit, B

    2012-11-21

    Large-scale simulations of aluminosilicate zeolites were conducted to identify structures that possess large CO2 uptake for postcombustion carbon dioxide capture. In this study, we discovered that the aluminosilicate zeolite structures with the highest CO2 uptake values have an idealized silica lattice with a large free volume and a framework topology that maximizes the regions with nearest-neighbor framework atom distances from 3 to 4.5 angstrom. These predictors extend well to different Si:Al ratios and for both Na+ and Ca2+ cations, demonstrating their universal applicability in identifying the best-performing aluminosilicate zeolite structures.

  2. Amphiphilic properties of poly(oxyalkylene)amine-intercalated smectite aluminosilicates.

    PubMed

    Lin, Jiang-Jen; Chen, Yu-Min

    2004-05-11

    Layered aluminosilicates, including synthetic fluorine mica and natural montmorillonite (MMT), were intercalated with poly(oxypropylene)-polyamine quaternary salts with a 230-5000 molecular weight range. The X-ray basal spacing of these silicates had been expanded from 13.5 to 83.7 A for the synthetic mica and to 92.0 A for MMT. The relative silicate dimensions (300-1000 nm for synthetic mica and 80-100 nm for MMT) were ascertained by direct TEM observations in the case of the co-intercalated synthetic mica and MMT mixtures with Mw = 2000 quaternary ammonium salts. The tailored organic incorporation of synthetic mica and MMT clays could alter these hydrophilic clays, making them amphiphilic, and enable the lowering of toluene/water interfacial tension to 2.0 mN/m at the critical concentration of 0.1 wt %.

  3. Sorption of cesium ions by nanostructured calcium aluminosilicates

    NASA Astrophysics Data System (ADS)

    Gordienko, P. S.; Shabalin, I. A.; Yarusova, S. B.; Suponina, A. P.; Zhevtun, I. G.

    2016-10-01

    Data on the sorption properties of synthetic calcium aluminosilicates (CASes) with Al: Si ratios of 2: 2, 2: 6, and 2: 10, fabricated within the multicomponent system CaCl2-AlCl3-KOM-SiO2-H2O, are presented. Isotherms of the sorption of Cs+ ions from aqueous solutions with Cs+ concentrations of 0.2 to 6.0 mmol L-1 are analyzed. The CAS maximum sorption capacity and the Langmuir constants are determined. Kinetic data are obtained, and the energy of cation-exchange activation upon the sorption of Cs+ ions is determined. The effect of a salt background (1% KCl + 6% NaCl) has on the values of distribution coefficient ( K d) and the degree of Cs+ ion removal is established.

  4. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  5. Rationale for windshield glass system specification requirements for shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Hayashida, K.; King, G. L.; Tesinsiky, J.; Wittenburg, D. R.

    1972-01-01

    A preliminary procurement specification for the space shuttle orbiter windshield pane, and some of the design considerations and rationale leading to its development are presented. The windshield designer is given the necessary methods and procedures for assuring glass pane structural integrity by proof test. These methods and procedures are fully developed for annealed and thermally tempered aluminosilicate, borosilicate, and soda lime glass and for annealed fused silica. Application of the method to chemically tempered glass is considered. Other considerations are vision requirements, protection against bird impact, hail, frost, rain, and meteoroids. The functional requirements of the windshield system during landing, ferrying, boost, space flight, and entry are included.

  6. XAFS Studies of Silver Environments in Ion-Exchanged Glasses

    SciTech Connect

    Yang, X. C.; Dubiel, M.

    2007-02-02

    The X-ray absorption fine structure (XAFS) technique was used to analyze the structural geometry of Ag atoms introduced into soda-lime silicate glass and soda aluminosilicate glass by ion-exchange methods. The results show that Ag+ ions in aluminosilicate glass are coordinated by about two oxygens and the nearest-neighbor Ag-O distance increases when the Ag+-for-Na+ ion-exchange ratio is larger than 0.47. When the exchange ratio is low, the introduced Ag+ ions are stabilized at the non-bridge oxygen (NBO) site with a Ag-O distance of 2.20 A, and the Na+ ions in the AlO4 site are exchanged by Ag+ ions after full replacement of the NBO sites with a Ag-O distance of 2.28 A. The disorder of Ag-O coordination increases with increasing ion-exchange ratio in aluminosilicate glass where Ag+ ions are coordinated by NBO and bridge oxygen (BO)

  7. Reactions in glass ionomer cements: V. Effect of incorporating tartaric acid in the cement liquid.

    PubMed

    Crisp, S; Wilson, A D

    1976-01-01

    A description is give of the effect on the ASPA cement reaction of tartaric acid incorporated in the cement liquid. Tartaric acid acts as an accelerator that aids in the extraction of ions from the aluminosilicate glass and facilitates their binding to the polyanion chains. Postgelation hardening is significantly increased. Working time is unaffected possibly because cations are initially present as complexes.

  8. Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materials.

    DTIC Science & Technology

    1986-03-31

    stress corrosion susceptibility, chemical effects during crack growth and the static fatigue limit. After a general discussion of chemical effects in...106 * CHAPTER V. Stress Corrosion of Sodium-Aluminosilicate Glasses: A Comparison of Small and Large Cracks ............. 123... crack growth behavior. It leads naturally to the conclusion that the composition dependence of the stress corrosion susceptibility is due to

  9. A model for phosphate glass topology considering the modifying ion sub-network

    NASA Astrophysics Data System (ADS)

    Hermansen, Christian; Mauro, John C.; Yue, Yuanzheng

    2014-04-01

    In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent with available structural data by NMR and molecular dynamics simulations and with dynamic data such glass transition temperature (Tg) and liquid fragility (m). Alkali phosphate glasses are exemplary systems for developing constraint model since the modifying cation network plays an important role besides the primary phosphate network. The proposed topological model predicts the changing trend of the Tg and m with increasing alkali oxide content for alkali phosphate glasses, including an anomalous minimum at around 20 mol.% alkali oxide content. We find that the minimum in Tg and m is caused by increased connectivity of the modifying ion sub-network, as the alkali ions must share non-bonding oxygen to satisfy their coordination requirements at higher alkali oxide contents. We argue that the systematically decreasing the Tg values of alkali phosphate glasses from Li2O to Na2O to Cs2O could be caused by a weakening of the modifying ion sub-network and can be accounted for by lower constraint onset temperatures.

  10. Upgrading platform using alkali metals

    DOEpatents

    Gordon, John Howard

    2017-01-17

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

  11. Upgrading platform using alkali metals

    SciTech Connect

    Gordon, John Howard

    2014-09-09

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

  12. The influence of sodium carbonate on sodium aluminosilicate crystallisation and solubility in sodium aluminate solutions

    NASA Astrophysics Data System (ADS)

    Zheng, Kali; Gerson, Andrea R.; Addai-Mensah, Jonas; Smart, Roger St. C.

    1997-01-01

    Isothermal batch precipitation experiments have been carried out in synthetic Bayer liquors to investigate the effects of sodium carbonate concentration on both silica solubility and the crystallisation of sodium aluminosilicates. At both 90 and 160°C cancrinite (generically defined as a sodium aluminosilicate of space group P6 3) is the stable solid phase. Sodalite (generically defined as a sodium aluminosilicate with space group P4¯3n seed transforms to cancrinite at both these temperatures. A high concentration of sodium carbonate in the synthetic liquor causes a decrease in the rate of conversion of sodalite to cancrinite. The solubility of both cancrinite and sodalite decreases as the concentration of sodium carbonate in the synthetic liquor is increased. For instance at 90°C and with 40.0 g dm -3 sodium carbonate in the synthetic liquor after 13 days the sodium aluminosilicate concentration is 0.52 g dm -3 compared to 0.85 g dm -3 with 4.6 g dm -3 of sodium carbonate in solution. At 160°C the sodium aluminosilicate concentration is 0.47 g dm -3 with 40.0 g dm -3 sodium carbonate in solution after 13 days and 0.79 g dm -3 with 4.6 g dm -3 sodium carbonate in solution. Throughout all these experiments a progressive loss of carbonate from the sodium aluminosilicate crystallisation products was observed as a function of time.

  13. Measurement of alkali vapor in PFBC flue gas and its control by a fixed granular bed of activated bauxite

    SciTech Connect

    Lee, S.H.D.; Myles, K.M.

    1985-01-01

    A fixed granular-bed sorber, with regenerable activated bauxite as the sorbent, for the control of the alkali vapor in the flue gas produced during pressurized fluidized-bed combustion (PFBC) of coal is being developed. In a gas stream closely simulating the actual PFBC flue gas, activated bauxite is shown to capture NaCl vapor by (1) chemical fixation of the vapor with the intrinsic clay minerals, probably to form thermally stable, water-insoluble sodium aluminosilicates and (2) chemical conversion of NaCl vapor into a condensed-phase sodium sulfate, which has a much lower vapor pressure than does NaCl. The latter predominates the capture process, and the captured sodium sulfate can be easily removed by simple water-leaching to restore the porosity of activated bauxite for reuse. A high-temperature (less than or equal to 900/sup 0/C) and high-pressure (less than or equal to 10 atm) laboratory-scale, fixed, granular-bed alkali sorber has been operated with the Argonne National Laboratory PFBC combustor to (1) measure the alkali vapor concentration in the PFBC flue gas on a real-time, on-line basis, and (2) demonstrate the alkali sorber for the control of alkali vapor from an actual PFBC flue gas. The alkali (Na + K) vapor concentration in particulate filtered hot flue gas was measured to be <10 ppbW with the Ames analyzer. The same measurement with the APST was higher between 90 to 170 ppbW. Therefore, the possibility of sink for sodium vapor in the PFBC/alkali sorber system must be considered. 32 refs.

  14. Glass as a waste form for the immobilization of plutonium

    SciTech Connect

    Bates, J.K.; Ellison, A.J.G.; Emery, J.W.; Hoh, J.C.

    1995-12-31

    Several alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkali-tin-silicate glass.

  15. A New Titanium-Bearing Calcium Aluminosilicate Phase. 1; Meteoritic Occurrences and Formation in Synthetic Systems

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Beckett, John R.; Barber, David J.; Stolper, Edward M.

    1994-01-01

    A new titanium-bearing calcium aluminosilicate mineral has been identified in coarse-grained calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites. The formula for this phase, which we have temporarily termed "UNK," is Ca3Ti(AlTi)2(Si,Al)3O14, and it is present in at least 8 of the 20 coarse-grained CAIs from the Allende CV3 chondrite examined as part of this project. The phase occurs in Types A and B1 inclusions as small tabular crystals oriented along two mutually perpendicular planes in melilite. UNK crystallizes from melts in dynamic crystallization experiments conducted in air from four bulk compositions modeled after Types A, B1, B2 and C inclusions. Cooling rates resulting in crystallization of UNK ranged from 0.5 to 200 C/h from maximum (initial) temperatures of 1375 to 1580 C. Only below 1190 C does UNK itself begin to crystallize. To first order, the presence or absence of UNK from individual experiments can be understood in terms of the compositions of residual melts and nucleation probabilities. Compositions of synthetic and meteoritic LINK are very similar in terms of major oxides, differing only in the small amounts of trivalent Ti (7-13% of total Ti) in meteoritic samples. UNK crystallized from the Type A analog is similar texturally to that found in CAls, although glass, which is typically associated with synthetic UN& is not observed in meteoritic occurrences. A low Ti end-member of UNK ("Si-UNK") with a composition new that of Ca3Al2Si4O14 was produced in a few samples from the Type B1 analog. This phase has not been found in the meteoritic inclusions.

  16. A new titanium-bearing calcium aluminosilicate phase. 1: Meteoritic occurrences and formation in synthetic systems

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Beckett, John R.; Barber, David J.; Stolper, Edward M.

    1994-01-01

    A new titanium-bearing calcium aluminosilicate mineral has been identified in coarse-grained calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites. The formula for this phase, which we have temporarily termed 'UNK,' is Ca3Ti(Al,Ti)2(Si,Al)3O14, and it is present in at least 8 of the 20 coarse-grained CAIs from the Allende CV3 chondrite examined as part of this project. The phase occurs in Types A and B1 inclusions as small tabular crystal oriented along two mutually perpendicular planes in melilite. UNK crystallizes from melts in dynamic crystallization experiments conducted in air from four bulk compositions modeled after Types A, B1, B2 and C inclusions. Cooling rates resulting in crystallization of UNK ranged from 0.5 to 200 C/h from maximum (initial) temperatures of 1375 to 1580 C. Only below 1190 C does UNK itself begin to crystallize. To first order, the presence or absence of UNK from individual experiments can be understood in terms of the compositions of residual melts and nucleation probabilities. Compositions of synthetic and meteoritic UNK are very similar in terms of major oxides, differing only in the small amounts of trivalent Ti(7-13% of total Ti) in meteoritic samples. UNK crystallized from the Type A analog is similar texturally to that found in CAIs, although glass, which is typically associated with synthetic UNK, is not observed in the meteoritic occurrences. A low Ti end-member of UNK ('Si-UNK') with a composition near that of Ca3Al2Si4O14 was produced in a few samples from the Type B1 analog. This phase has not been found in the meteoritic inclusions.

  17. NOVEL REFRACTORY MATERIALS FOR HIGH ALKALI, HIGH TEMPERATURE ENVIRONMENTS

    SciTech Connect

    Hemrick, James Gordon; Smith, Jeffrey D; O'Hara, Kelley; Rodrigues-Schroer, Angela; Colavito,

    2012-08-01

    A project was led by Oak Ridge National Laboratory (ORNL) in collaboration with a research team comprised of the academic institution Missouri University of Science and Technology (MS&T), and the industrial company MINTEQ International, Inc. (MINTEQ), along with representatives from the aluminum, chemical, glass, and forest products industries. The project was to address the need for new innovative refractory compositions by developing a family of novel MgO-Al 2O3, MgAl2O4, or other similar spinel structured or alumina-based unshaped refractory compositions (castables, gunnables, shotcretes, etc.) utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques (in-situ phase formation, altered conversion temperatures, accelerated reactions, etc). This family of refractory compositions would then be tailored for use in high-temperature, high-alkaline industrial environments like those found in the aluminum, chemical, forest products, glass, and steel industries. Both practical refractory development experience and computer modeling techniques were used to aid in the design of this new family of materials. The newly developed materials were expected to offer alternative material choices for high-temperature, high-alkali environments that were capable of operating at higher temperatures (goal of increasing operating temperature by 100-200oC depending on process) or for longer periods of time (goal of twice the life span of current materials or next process determined service increment). This would lead to less process down time, greater energy efficiency for associated manufacturing processes (more heat kept in process), and materials that could be installed/repaired in a more efficient manner. The overall project goal was a 5% improvement in energy efficiency (brought about through a 20% improvement in thermal efficiency) resulting in a savings of 3.7 TBtu/yr (7.2 billion ft3 natural gas) by the year 2030. Additionally, new

  18. Antiferromagnetic resonance in alkali-metal clusters in sodalite

    NASA Astrophysics Data System (ADS)

    Nakano, Takehito; Tsugeno, Hajime; Hanazawa, Atsufumi; Kashiwagi, Takanari; Nozue, Yasuo; Hagiwara, Masayuki

    2013-11-01

    We have performed electron spin resonance (ESR) studies of K43+ and (K3Rb)3+ nanoclusters incorporated in powder specimens of aluminosilicate sodalite at several microwave frequencies between 9 and 34 GHz. The K43+ and (K3Rb)3+ clusters are arrayed in a bcc structure and are known to show antiferromagnetic ordering below the Néel temperatures of TN ≃72 and ≃80 K, respectively, due to the exchange coupling between s electrons confined in the clusters. We have found sudden broadenings of ESR spectra in both samples below TN. The line shape of the spectra below TN is analyzed by powder pattern simulations of antiferromagnetic resonance (AFMR) spectra. The calculated line shapes well reproduce the experimental ones at all the frequencies by assuming a biaxial magnetic anisotropy. We have evaluated extremely small anisotropy fields of approximately 1 Oe indicating that these materials are ideal Heisenberg antiferromagnets. We have also found that the magnetic anisotropy changes from easy-plane type to uniaxial type by changing into a heavier alkali-metal cluster and that the g value shifts to a large value beyond two below TN for K43+ and (K3Rb)3+ nanoclusters. These novel features of K43+ and (K3Rb)3+ nanoclusters incorporated in sodalite are discussed.

  19. Low melting high lithia glass compositions and methods

    DOEpatents

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2003-09-23

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste uranium oxides The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  20. Surface functionalization of aluminosilicate nanotubes with organic molecules

    PubMed Central

    Ma, Wei; Yah, Weng On; Otsuka, Hideyuki

    2012-01-01

    Summary The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH) surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid (HT3P) and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid 1,1-dioxide (HT3OP), on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene) (P3HT) chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid. PMID:22428100

  1. Development of aluminosilicate polyelectrolytes for solid-state battery applications

    SciTech Connect

    Rawsky, G.C.; Henretta, K.J.; Shriver, D.F.; Lowrey, R.; Vaynman, S.

    1995-12-31

    The authors have synthesized and characterized a range of novel polyelectrolytes containing weakly basic aluminosilicate anions in the polymer backbone in order to achieve t{sub +} = 1 and high ionic mobility. Room-temperature conductivity is observed to increase in the series: [NaAl(OEOMe){sub 2} ((OE){sub x}O){sub 2/2}]{sub n} < [NaAl(OR){sub 2}(OSiMe{sub 2}(CH{sub 2}){sub 3}(OE){sub x}O(CH{sub 2}){sub 3}SiMe{sub 2}O){sub 2/2}]{sub n} < [NaAl(OSiR{sub 3})(OSiMe{sub 2}(CH{sub 2}){sub 3}(OE){sub x}O(CH{sub 2}){sub 3}SiMe{sub 2}O){sub 3/2}]{sub n}. This trend is ascribed to reduced ion pairing due to decreasing anion basicity, and lowered T{sub g} resulting from increasing siloxy character. The addition of cryptang [2.2.2] increases conductivity by 1--1.5 orders of magnitude. A maximum room-temperature conductivity is observed at a ratio of {approx}10 etheric oxygens/cation. Related lithium polymer electrolytes were evaluated in mechanically joined solid state Li{vert_bar}PE{vert_bar}[Li{sub x}Mn{sub 2}O{sub 4}-C-PE] cells.

  2. Ageing characteristics of aluminium alloy aluminosilicate discontinuous fiber reinforced composites

    SciTech Connect

    Nath, D.; Singh, V.

    1999-03-05

    Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

  3. Binding and catalytic reduction of NO by transition metal aluminosilicates

    SciTech Connect

    Klier, K.; Herman, R.G.; Hou, Shaolie.

    1991-09-01

    The objective of this research is to provide the scientific understanding of processes that actively and selectively reduce NO in dilute exhaust streams, as well as in concentrated streams, to N{sub 2}. Experimental studies of NO chemistry in transition metal-containing aluminosilicate catalysts are being carried out with the aim of determining the chemical rules for NO reduction on non-precious metals. The catalyst supports chosen for this investigation are A and Y zeolites, mordenite, and monoliths based on cordierite. The supported transition metal cations that were examined are principally the first row redox metals, e.g. Cr(2), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Cu(I). The reactions of interest are the reductions of NO by H{sub 2}, CO, and CH{sub 4}, as well as the disproportionation of NO. Rare earth cations that possess redox properties were placed in the more shielded sites, e.g. Site I in Y zeolite, prior to or simultaneously with the exchange procedure with the transition metal cations. Theoretical calculations of the electronic structure of the transition metal cations in zeolitic sites were carried out by ab initio methods. The aim of this part of the research is to find the best match between the metal-based antibonding orbitals and the antibonding orbitals of the NO molecule such that the N-O bond is weakened and is readily broken. 9 refs., 4 figs., 3 tabs.

  4. SODIUM ALUMINOSILICATE SOLIDS AFFINITY FOR CESIUM AND ACTINIDES

    SciTech Connect

    Peters, T; Bill Wilmarth, B; Samuel Fink, S

    2007-07-31

    Washed sodium-aluminosilicate (NAS) solids at initial concentrations of 3.55 and 5.4 g/L sorb or uptake virtually no cesium over 288 hours, nor do any NAS solids generated during that time. These concentrations of solids are believed to conservatively bound current and near-term operations. Hence, the NAS solids should not have affected measurements of the cesium during the mass transfer tests and there is minimal risk of accumulating cesium during routine operations (and hence posing a gamma radiation exposure risk in maintenance). With respect to actinide uptake, it appears that NAS solids sorb minimal quantities of uranium - up to 58 mg U per kg NAS solid. The behavior with plutonium is less well understood. Additional study may be needed for radioactive operations relative to plutonium or other fissile component sorption or trapping by the solids. We recommend this testing be incorporated in the planned tests using samples from Tank 25F and Tank 49H to extend the duration to bound expected inventory time for solution.

  5. Cathodoluminescence Characterization of Maskelynite and Alkali Feldspar in Shergottite (Dhofar 019)

    SciTech Connect

    Kayama, M.; Nakazato, T.; Nishido, H.; Ninagawa, K.; Gucsik, A.

    2009-08-17

    Dhofar 019 is classified as an olivine-bearing basaltic shergottite and consists of subhedral grains of pyroxene, olivine, feldspar mostly converted to maskelynite and minor alkali feldspar. The CL spectrum of its maskelynite exhibits an emission band at around 380 nm. Similar UV-blue emission has been observed in the plagioclase experimentally shocked at 30 and 40 GPa, but not in terrestrial plagioclase. This UV-blue emission is a notable characteristic of maskelynite. CL spectrum of alkali feldspar in Dhofar 019 has an emission bands at around 420 nm with no red emission. Terrestrial alkali feldspar actually consists of blue and red emission at 420 and 710 nm assigned to Al-O{sup -}-Al and Fe{sup 3+} centers, respectively. Maskelynite shows weak and broad Raman spectral peaks at around 500 and 580 cm{sup -1}. The Raman spectrum of alkali feldspar has a weak peak at 520 cm{sup -1}, whereas terrestrial counterpart shows the emission bands at 280, 400, 470, 520 and 1120 cm{sup -1}. Shock pressure on this meteorite transformed plagioclase and alkali feldspar into maskelynite and almost glass phase, respectively. It eliminates their luminescence centers, responsible for disappearance of yellow and/or red emission in CL of maskelynite and alkali feldspar. The absence of the red emission band in alkali feldspar can also be due to the lack of Fe{sup 3+} in the feldspar as it was reported for some lunar feldspars.

  6. X-ray microtomography shows pore structure and tortuosity in alkali-activated binders

    SciTech Connect

    Provis, John L.; Myers, Rupert J.; White, Claire E.; Rose, Volker; Deventer, Jannie S.J. van

    2012-06-15

    Durability of alkali-activated binders is of vital importance in their commercial application, and depends strongly on microstructure and pore network characteristics. X-ray microtomography ({mu}CT) offers, for the first time, direct insight into microstructural and pore structure characteristics in three dimensions. Here, {mu}CT is performed on a set of sodium metasilicate-activated fly ash/slag blends, using a synchrotron beamline instrument. Segmentation of the samples into pore and solid regions is then conducted, and pore tortuosity is calculated by a random walker method. Segmented porosity and diffusion tortuosity are correlated, and vary as a function of slag content (slag addition reduces porosity and increases tortuosity), and sample age (extended curing gives lower porosity and higher tortuosity). This is particularly notable for samples with {>=} 50% slag content, where a space-filling calcium (alumino)silicate hydrate gel provides porosity reductions which are not observed for the sodium aluminosilicate ('geopolymer') gels which do not chemically bind water of hydration.

  7. Utilization of calcite and waste glass for preparing construction materials with a low environmental load.

    PubMed

    Maeda, Hirotaka; Imaizumi, Haruki; Ishida, Emile Hideki

    2011-11-01

    In this study, porous calcite materials are hydrothermally treated at 200 °C using powder compacts consisting of calcite and glasses composed of silica-rich soda-lime. After treatment, the glasses are converted into calcium aluminosilicate hydrates, such as zeolite phases, which increase their strength. The porosity and morphology of new deposits of hydrothermally solidified materials depend up on the chemical composition of glass. The use of calcite and glass in the hydrothermal treatment plays an important role in the solidification of calcite without thermal decomposition.

  8. Geopolymers prepared from DC plasma treated air pollution control (APC) residues glass: properties and characterisation of the binder phase.

    PubMed

    Kourti, Ioanna; Devaraj, Amutha Rani; Bustos, Ana Guerrero; Deegan, David; Boccaccini, Aldo R; Cheeseman, Christopher R

    2011-11-30

    Air pollution control (APC) residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium aluminosilicate glass (APC glass). This has been used to form geopolymer-glass composites that exhibit high strength and density, low porosity, low water absorption, low leaching and high acid resistance. The composites have a microstructure consisting of un-reacted residual APC glass particles imbedded in a complex geopolymer and C-S-H gel binder phase, and behave as particle reinforced composites. The work demonstrates that materials prepared from DC plasma treated APC residues have potential to be used to form high quality pre-cast products.

  9. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

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

  10. Healing of lithographically introduced flaws in glass and glass containing ceramics

    SciTech Connect

    Ackler, H.D.

    1992-12-01

    The morphological evolution of cylindrical pores or channels'' and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al[sub 2]O[sub 3]with [approx]5--10% intergranular glass, 96% Al[sub 2]O[sub 3] bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces of sapphire onto which 30--50 nm of SiO[sub 2] had been sputter deposited. These systems span a broad range of glass contents, and permit observation of healing behavior with varying glass content. The results were compared with analytical models and results of similar studies in completely crystalline systems.

  11. Healing of lithographically introduced flaws in glass and glass containing ceramics

    SciTech Connect

    Ackler, H.D.

    1992-12-01

    The morphological evolution of cylindrical pores or ``channels`` and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al{sub 2}O{sub 3}with {approx}5--10% intergranular glass, 96% Al{sub 2}O{sub 3} bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces of sapphire onto which 30--50 nm of SiO{sub 2} had been sputter deposited. These systems span a broad range of glass contents, and permit observation of healing behavior with varying glass content. The results were compared with analytical models and results of similar studies in completely crystalline systems.

  12. Alkali Metal Cluster Theory.

    NASA Astrophysics Data System (ADS)

    Chen, Jian

    Available from UMI in association with The British Library. Requires signed TDF. In this thesis, we apply the tight-binding Hubbard model to alkali metal clusters with Hartree-Fock self-consistent methods and perturbation methods for the numerical calculations. We have studied the relation between the equilibrium structures and the range of the hopping matrix elements in the Hubbard Hamiltonian. The results show that the structures are not sensitive to the interaction range but are determined by the number of valence electrons each atom has. Inertia tensors are used to analyse the symmetries of the clusters. The principal axes of the clusters are determined and they are the axes of rotational symmetries of clusters if the clusters have any. The eigenvalues of inertia tensors which are the indication of the deformation of clusters are compared between our model and the ellipsoidal jellium model. The agreement is good for large clusters. At a finite temperature, the thermal motion fluctuates the structures. We defined a fluctuation function with the distance matrix of a cluster. The fluctuation has been studied with the Monte-Carlo simulation method. Our studies show that the clusters remain in the solid state when temperature is low. The small values of fluctuation functions indicates the thermal vibration of atoms around their equilibrium positions. If the temperature is high, the atoms are delocalized. The cluster melts and enters the liquid region. The cluster melting is simulated by the Monte-Carlo simulation with the fluctuation function we defined. Energy levels of clusters are calculated from the Hubbard model. Ionization potentials and magic numbers are also obtained from these energy levels. The results confirm that the Hubbard model is a good approximation for a small cluster. The excitation energy is presented by the difference between the original level and excited level, and the electron-hole interactions. We also have studied cooling of clusters

  13. Detecting Nanophase Weathering Products with CheMin: Reference Intensity Ratios of Allophane, Aluminosilicate Gel, and Ferrihydrite

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Bish, D. L.; Chipera, S. J.; Morris, R. V.; Achilles, C. N.; Ming, D W.; Blake, D. F.; Anderson, R. C.; Bristow, T. F.; Crisp, A.; DesMarais, D. J.; Downs, R. T.; Farmer, J. D.; Morookian, J. M.; Morrison, S. M.; Sarrazin, P.; Spanovich, N.; Stolper, E. M.; Treiman, A. H.; Vaniman, D. T.; Yen, A. S.

    2013-01-01

    X-ray diffraction (XRD) data collected of the Rocknest samples by the CheMin instrument on Mars Science Laboratory suggest the presence of poorly crystalline or amorphous materials [1], such as nanophase weathering products or volcanic and impact glasses. The identification of the type(s) of X-ray amorphous material at Rocknest is important because it can elucidate past aqueous weathering processes. The presence of volcanic and impact glasses would indicate that little chemical weathering has occurred because glass is highly susceptible to aqueous alteration. The presence of nanophase weathering products, such as allophane, nanophase iron-oxides, and/or palagonite, would indicate incipient chemical weathering. Furthermore, the types of weathering products present could help constrain pH conditions and identify which primary phases altered to form the weathering products. Quantitative analysis of phases from CheMin data is achieved through Reference Intensity Ratios (RIRs) and Rietveld refinement. The RIR of a mineral (or mineraloid) that relates the scattering power of that mineral (typically the most intense diffraction line) to the scattering power of a separate mineral standard such as corundum [2]. RIRs can be calculated from XRD patterns measured in the laboratory by mixing a mineral with a standard in known abundances and comparing diffraction line intensities of the mineral to the standard. X-ray amorphous phases (e.g., nanophase weathering products) have broad scattering signatures rather than sharp diffraction lines. Thus, RIRs of X-ray amorphous materials are calculated by comparing the area under one of these broad scattering signals with the area under a diffraction line in the standard. Here, we measured XRD patterns of nanophase weathering products (allophane, aluminosilicate gel, and ferrihydrite) mixed with a mineral standard (beryl) in the CheMinIV laboratory instrument and calculated their RIRs to help constrain the abundances of these phases in

  14. Rb based alkali antimonide high quantum efficiency photocathodes for bright electron beam sources and photon detection applications

    NASA Astrophysics Data System (ADS)

    Cultrera, L.; Gulliford, C.; Bartnik, A.; Lee, H.; Bazarov, I.

    2017-02-01

    High quantum efficiency alkali antimonide photocathodes have been grown over both stainless steel and glass substrates using sequential evaporation of Sb, K, Rb, and Cs. Quantum efficiencies well above 25% have been measured at 400 nm. A bi-alkali Rb-K-Sb photocathode grown on a stainless steel substrate has been installed in a high voltage DC gun at Cornell University and the intrinsic electron beam emittance was measured at different photon energies.

  15. Process for direct conversion of reactive metals to glass

    DOEpatents

    Rajan, John B.; Kumar, Romesh; Vissers, Donald R.

    1990-01-01

    Radioactive alkali metal is introduced into a cyclone reactor in droplet form by an aspirating gas. In the cyclone metal reactor the aspirated alkali metal is contacted with silica powder introduced in an air stream to form in one step a glass. The sides of the cyclone reactor are preheated to ensure that the initial glass formed coats the side of the reactor forming a protective coating against the reactants which are maintained in excess of 1000.degree. C. to ensure the formation of glass in a single step.

  16. FTIR Analysis of Alkali Activated Slag and Fly Ash Using Deconvolution Techniques

    NASA Astrophysics Data System (ADS)

    Madavarapu, Sateesh Babu

    The studies on aluminosilicate materials to replace traditional construction materials such as ordinary Portland cement (OPC) to reduce the effects caused has been an important research area for the past decades. Many properties like strength have already been studied and the primary focus is to learn about the reaction mechanism and the effect of the parameters on the formed products. The aim of this research was to explore the structural changes and reaction product analysis of geopolymers (Slag & Fly Ash) using Fourier transform infrared spectroscopy (FTIR) and deconvolution techniques. Spectroscopic techniques give valuable information at a molecular level but not all methods are economic and simple. To understand the mechanisms of alkali activated aluminosilicate materials, attenuated total reflectance (ATR) FTIR has been used where the effect of the parameters on the reaction products have been analyzed. To analyze complex systems like geopolymers using FTIR, deconvolution techniques help to obtain the properties of a particular peak attributed to a certain molecular vibration. Time and temperature dependent analysis were done on slag pastes to understand the polymerization of reactive silica in the system with time and temperature variance. For time dependent analysis slag has been activated with sodium and potassium silicates using two different `n'values and three different silica modulus [Ms- (SiO2 /M2 O)] values. The temperature dependent analysis was done by curing the samples at 60°C and 80°C. Similarly fly ash has been studied by activating with alkali hydroxides and alkali silicates. Under the same curing conditions the fly ash samples were evaluated to analyze the effects of added silicates for alkali activation. The peak shifts in the FTIR explains the changes in the structural nature of the matrix and can be identified using the deconvolution technique. A strong correlation is found between the concentrations of silicate monomer in the

  17. Valorization of sugarcane bagasse ash: producing glass-ceramic materials.

    PubMed

    Teixeira, S R; Magalhães, R S; Arenales, A; Souza, A E; Romero, M; Rincón, J M

    2014-02-15

    Some aluminosilicates, for example mullite and wollastonite, are very important in the ceramic and construction industries. The most significant glass-ceramic for building applications has wollastonite as the main crystal phase. In this work we report on the use of sugarcane bagasse ash (SCBA) to produce glass-ceramics with silicates as the major crystalline phases. The glasses (frits) were prepared by mixing ash, limestone (calcium and magnesium carbonates) and potassium carbonate as the fluxing agent. X-ray fluorescence was used to determine the chemical composition of the glasses and their crystallization was assessed by using thermal analysis (DTA/DSC/TGA) and X-ray diffraction. The results showed that glass-ceramic material can be produced with wollastonite as the major phase, at a temperature lower than 900 °C.

  18. Aqueous dissolution of sodium aluminosilicate geopolymers derived from metakaolin

    NASA Astrophysics Data System (ADS)

    Aly, Z.; Vance, E. R.; Perera, D. S.

    2012-05-01

    In dilute aqueous solutions, the elemental releases of Na, Al and Si from a metakaolin-based sodium aluminosilicate geopolymer were not very sensitive to pH in the range of 4-10 but increased outside this range, particularly on the acidic side. To minimise pH drifts, experiments were carried out using small amounts of graded powders in relatively large volumes of water. In deionised water, the Na dissolution rate in 7 days was dominant and increased by at least a factor of ˜4 on heating from 18 to 90 °C, with greater increases in the extractions of Al and Si. At 18 °C the elemental extractions in deionised water increased approximately linearly with time over the 1-7 days period. Further exposure led to a slower extraction into solution for Na and Si, with a decrease in extraction of Al. It was deduced that framework dissolution was important in significantly acidic or alkaline solutions, but that contributions from water transfer from pores to elemental extractions were present, even at low temperatures in neutral solutions. It was also deduced from the Na release data that the Na leaching kinetics of geopolymer in deionised water (dilute solutions) followed the pseudo-second-order kinetic model and the pseudo-second-order rate constant evaluated. Contact with KCl, KHCO3, and pH ˜6 and 10 potassium phthalate buffer solutions gave rise to a high degree of Na+ ↔ K+ exchange and rendered the framework ions less leachable in water.

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

    DOEpatents

    Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

    2011-12-13

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

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

    DOEpatents

    Gordon, John Howard; Alvare, Javier

    2016-10-25

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

  1. Li{sup +} alumino-silicate ion source development for the neutralized drift compression experiment

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2011-01-15

    We report results on lithium alumino-silicate ion source development in preparation for warm dense matter heating experiments on the new neutralized drift compression experiment II. The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of {approx_equal}1275 deg. C, a space-charge limited Li{sup +} beam current density of J {approx_equal}1 mA/cm{sup 2} was obtained. The lifetime of the ion source was {approx_equal}50 h while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 {mu}s.

  2. Evidence for lithium-aluminosilicate supersaturation of pegmatite-forming melts

    NASA Astrophysics Data System (ADS)

    Maneta, Victoria; Baker, Don R.; Minarik, William

    2015-07-01

    New experimental data on the solubility of lithium (Li) at spodumene (LiAlSi2O6) and petalite (LiAlSi4O10) saturation at 500 MPa and 550-750 °C reveal evidence for lithium supersaturation of pegmatite-forming melts before the formation of Li-aluminosilicates. The degree of Li enrichment in granitic melts can reach ~11,000 ppm above the saturation value before the crystallization of Li-aluminosilicate minerals at lower temperatures. Comparison of the experimental results with the spodumene-rich Moblan pegmatite (Quebec) is consistent with extreme Li enrichment of the pegmatite-forming melt prior to emplacement, which cannot be explained with equilibrium crystallization of Li-aluminosilicates from a common granitic melt. The results of this study support the model of disequilibrium fractional crystallization through liquidus undercooling as the most plausible mechanism for the generation of such Li-rich ore resources.

  3. The effects of ochratoxin/aluminosilicate interaction on the tissues and humoral immune response of broilers.

    PubMed

    Santin, Elizabeth; Paulillo, Antonio C; Maiorka, Paulo C; Alessi, Antonio C; Krabbe, Everton L; Maiorka, Alex

    2002-02-01

    This study aimed to evaluate the effect of dietary ochratoxin, in the presence or absence of aluminosilicate, on the histology of the bursa of Fabricius, liver and kidneys, and on the humoral immune response of broilers vaccinated against Newcastle disease virus. The exposure of birds to 2 p.p.m. ochratoxin, in the presence or absence of aluminosilicate, reduced their humoral immune response and the number of mitotic cells in the bursa. The relative weight of the livers of the birds exposed to this toxin was increased and, microscopically, there was hepatocyte vacuolation and megalocytosis with accompanying hyperplasia of the biliary epithelium. The kidneys showed hypertrophy of the renal proximal tubular epithelium, with thickening of the glomerular basement membrane. Aluminosilicate did not ameliorate the deleterious effects of the ochratoxin.

  4. Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2010-10-01

    We report results on lithium alumino-silicate ion source development in preparation for warmdense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCXII). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ~;;1275 oC, a space-charge-limited Li+ beam current density of J ~;;1 mA/cm2 was obtained. The lifetime of the ion source was ~;;50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 mu s.

  5. Synthesis and immobilization of silver nanoparticles on aluminosilicate nanotubes and their antibacterial properties

    NASA Astrophysics Data System (ADS)

    Ipek Yucelen, G.; Connell, Rachel E.; Terbush, Jessica R.; Westenberg, David J.; Dogan, Fatih

    2016-04-01

    A novel colloidal method is presented to synthesize silver nanoparticles on aluminosilicate nanotubes. The technique involves decomposition of AgNO3 solution to Ag nanoparticles in the presence of aluminosilicate nanotubes at room temperature without utilizing of reducing agents or any organic additives. Aluminosilicate nanotubes are shown to be capable of providing a unique chemical environment, not only for in situ conversion of Ag+ into Ag0, but also for stabilization and immobilization of Ag nanoparticles. The synthesis strategy described here could be implemented to obtain self-assembled nanoparticles on other single-walled metal oxide nanotubes for unique applications. Finally, we demonstrated that nanotube/nanoparticle hybrid show strong antibacterial activity toward Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli.

  6. Electrical Resistivity of Alkali Elements.

    DTIC Science & Technology

    1976-01-01

    rubidium, cesium, and francium ) and contains recommended reference values (or provisional or typical values). The compiled data include all the...and information on the electrical resistivity of alkali elements (lithium, sodium, potassium, rubidium, cesium, and francium ) and contains...107Ic. Magnetic Flux Density Dependence o.. .. ... .... 112 4.6. Francium ..........................115j a. Temperature Dependence

  7. Interface Induced Growth and Transformation of Polymer-Conjugated Proto-Crystalline Phases in Aluminosilicate Hybrids: A Multiple-Quantum (23)Na-(23)Na MAS NMR Correlation Spectroscopy Study.

    PubMed

    Brus, Jiri; Kobera, Libor; Urbanova, Martina; Doušová, Barbora; Lhotka, Miloslav; Koloušek, David; Kotek, Jiří; Čuba, Pavel; Czernek, Jiri; Dědeček, Jiří

    2016-03-22

    Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix. This secondary epoxide phase not only enhances the mechanical integrity of the resulting hybrids but also introduces additional binding sites accessible for compensating negative charge on the aluminosilicate framework. This way, the polymer network initiates growth and subsequent transformation of protocrystalline short-range ordered zeolite domains that are located at the organic-inorganic interface. By applying an experimental approach based on 2D (23)Na-(23)Na double-quantum (DQ) MAS NMR spectroscopy, we discovered multiple sodium binding sites in these protocrystalline domains, in which immobilized Na(+) ions form pairs or small clusters. It is further demonstrated that these sites, the local geometry of which allows for the pairing of sodium ions, are preferentially occupied by Pb(2+) ions during the ion exchange. The proposed synthesis protocol thus allows for the preparation of a novel type of geopolymer hybrids with polymer-conjugated zeolite phases suitable for capturing and storage of metal cations. The demonstrated (23)Na-(23)Na DQ MAS NMR combined with DFT calculations represents a suitable approach for understanding the role of Na(+) ions in aluminositicate solids and related inorganic-organic hybrids, particularly their specific arrangement and clustering at interfacial areas.

  8. The Chemistry, Crystallization, Physicochemical Properties and Behavior of Sodium Aluminosilicate Solid Phases: Final Report

    SciTech Connect

    Rosencrance, S.

    2003-03-12

    The synthesis of sodium aluminosilicate solids phases precipitated from NO{sub 2}/NO{sub 3}-free and NO{sub 2}/NO{sub 3}-rich liquors has been performed. Four sodium aluminosilicate precipitation products were formed. These are (1) X-ray/electron diffraction-indifferent amorphous phase; (2) crystalline zeolite A; (3)NO{sub 2}/NO{sub 3}-rich crystalline sodalite; and (4) NO{sub 2}/NO{sub 3}-rich crystalline cancrinite phase. Characterization of the physicochemical properties for these phases has been performed under conditions simulating Westinghouse Savannah River Company liquid waste processing.

  9. Calculation of the Aluminosilicate Half-Life Formation Time in the 2H Evaporator

    SciTech Connect

    Fondeur, F.F.

    2000-09-21

    The 2H Evaporator contains large quantities of aluminosilicate solids deposited on internal fixtures. The proposed cleaning operations will dissolve the solids in nitric acid. Operations will then neutralize the waste prior to transfer to a waste tank. Combining recent calculations of heat transfer for the 2H Evaporator cleaning operations and laboratory experiments for dissolution of solid samples from the pot, the authors estimated the re-formation rate for aluminosilicates during cooling. The results indicate a half-life formation of 17 hours when evaporator solution cools from 60 degrees C and 9 hours when cooled from 90 degrees C.

  10. Technetium (VII) Co-precipitation with Framework Aluminosilicates

    SciTech Connect

    Harsh, James B.; Dickson, Johnbull Otah; Pierce, Eric M.; Bargar, John

    2015-07-13

    Technetium-99 (99Tc), a long-lived radionuclide, is one of the most widespread contaminants within the Hanford subsurface. At some depths, it is only extractable with strong acids, suggesting incorporation into a solid phase. We hypothesized that Tc may have coprecipitated with feldspathoid aluminosilicates under waste tanks that had leaked caustic solutions into the vadose zone. Our objectives were to determine if Tc could be incorporated into the feldspathoids cancrinite and sodalite and under what conditions coprecipitation could occur. Our hypothesis was that sodalite was more likely to incorporate and retain Tc. Our approach was to use known methods of feldspathoid formation in solutions resembling those in Hanford waste tanks contacting sediments in terms of major ion (Na, NO3, OH, Al(OH)4, and Si(OH)4 concentrations. In some cases, Al and Si were supplied from zeolite. We used perrhenate (ReO4) as a surrogate for pertechnetate (TcO4) to avoid the radioactivity. The major findings of this study were 1) ReO4 could be incorporated into either sodalite or cancrinite but the concentration in the solid was < 1% of the competing ion Cl, NO3, or NO2. 2) The small amount of ReO4 incorporated was not exchangeable with NO3 or NO2. 3) In sodalite, NO3 was highly preferred over ReO4 but significant Re-sodalite was formed when the mole fraction in solution (Re/Re+N) exceeded 0.8. 4) A nonlinear relation between the unit cell parameter and amount of Re incorporated suggested that a separate Re-sodalite phase was formed rather than a solid solution. 5) We determined that sodalite preference for sodalite in the presence of different anions increased with the ionic size of the competing anion: Cl < CO3 < NO3 < SO4 < MnO4 < WO4 and significant incorporation did not occur unless the difference in anion radii was less than 12%. 6) Re(VII) was not significantly reduced to Re(IV) under the conditions of this experiment and Re appeared to be a good surrogate for Tc under oxidizing

  11. Glass transition temperature and conductivity in Li2O and Na2O doped borophosphate glasses

    NASA Astrophysics Data System (ADS)

    Ashwajeet, J. S.; Sankarappa, T.; Ramanna, R.; Sujatha, T.; Awasthi, A. M.

    2015-08-01

    Two alkali doped Borophosphate glasses in the composition, (B2O3)0.2. (P2O5)0.3. (Na2O)(0.5-x). (Li2O)x, where x = 0.05 to 0.50 were prepared by standard melt quenching method at 1200K. Non-crystalline nature was confirmed by XRD studies. Room temperature density was measured by Archimedes principle. DC conductivity in the temperature range from 300K to 575K has been measured. Samples were DSC studied in the temperature range from 423K to 673K and glass transition temperature was determined. Glass transition temperature passed through minima for Li2O con.2centration between 0.25 and 0.30 mole fractions. Activation energy of conduction has been determined by analyzing temperature variation of conductivity determining Arrhenius law. Conductivity passed through minimum and activation passed through maximum for Li2O content from 0.25 to 0.30 mole fractions. Glass transition temperature passed through minimum for the same range of Li2O content. These results revealed mixed alkali effect taking place in these glasses. It is for the first time borophosphate glasses doped with Li2O and Na2O have been studied for density and dc conductivity and, the mixed alkali effect (MAE) has been observed.

  12. Comparison of the properties of glass, glass-ceramic and ceramic materials produced from coal fly ash.

    PubMed

    Erol, M; Küçükbayrak, S; Ersoy-Meriçboyu, A

    2008-05-01

    Glass, glass-ceramic and ceramic materials were produced from thermal power plant fly ash without any additives. X-ray diffraction (XRD) analysis revealed the amorphous phase of the glass sample. Augite phase was detected in the glass-ceramic sample, while the enstatite and mullite phases occurred in the ceramic samples. Scanning electron microscopy (SEM) investigations showed that tiny crystallites homogeneously dispersed in the microstructure of the glass-ceramic sample and elongated crystals formed in the ceramic samples. Density values of the obtained samples are comparable to those of the commercially produced glass, glass-ceramic and ceramic samples. Toxicity characteristic leaching procedure (TCLP) results indicated that the produced samples could be taken as non-hazardous materials. Produced samples showed high resistance to alkali solutions in contrast to acidic solutions. Microstructural, physical, chemical and mechanical properties of the produced glass-ceramic samples are better than those of the produced glass and ceramic samples.

  13. Glass sealing

    SciTech Connect

    Brow, R.K.; Kovacic, L.; Chambers, R.S.

    1996-04-01

    Hernetic glass sealing technologies developed for weapons component applications can be utilized for the design and manufacture of fuel cells. Design and processing of of a seal are optimized through an integrated approach based on glass composition research, finite element analysis, and sealing process definition. Glass sealing procedures are selected to accommodate the limits imposed by glass composition and predicted calculations.

  14. Positron-alkali atom scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.; Ward, S. J.

    1990-01-01

    Positron-alkali atom scattering was recently investigated both theoretically and experimentally in the energy range from a few eV up to 100 eV. On the theoretical side calculations of the integrated elastic and excitation cross sections as well as total cross sections for Li, Na and K were based upon either the close-coupling method or the modified Glauber approximation. These theoretical results are in good agreement with experimental measurements of the total cross section for both Na and K. Resonance structures were also found in the L = 0, 1 and 2 partial waves for positron scattering from the alkalis. The structure of these resonances appears to be quite complex and, as expected, they occur in conjunction with the atomic excitation thresholds. Currently both theoretical and experimental work is in progress on positron-Rb scattering in the same energy range.

  15. EFFECT OF IMPURITIES ASSOCIATED WITH ALUMINOSILICATES ON ARSENIC SORPTION AND OXIDATION

    EPA Science Inventory

    Arsenite, As(III), and arsenate, As(V), are of increasing environmental concern. Risk assessment and risk management of arsenic contaminated sites requires a better understanding of arsenic-mineral interactions. Aluminosilicate minerals, such as feldspars and clays, are the mos...

  16. Alkali metal/sulfur battery

    DOEpatents

    Anand, Joginder N.

    1978-01-01

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

  17. Effect of host glass matrix on structural and optical behavior of glass-ceramic nanocomposite scintillators

    NASA Astrophysics Data System (ADS)

    Brooke Barta, M.; Nadler, Jason H.; Kang, Zhitao; Wagner, Brent K.; Rosson, Robert; Kahn, Bernd

    2013-12-01

    Composite scintillator systems have received increased attention in recent years due to their promise for merging the radioisotope discrimination capabilities of single crystal scintillators with the high throughput scanning capabilities of portal monitors. However, producing the high light yield required for good energy resolution has proven challenging as scintillation photons are often scattered by variations in refractive index and agglomerated scintillator crystals within the composite. This investigation sought to mitigate these common problems by using glass-ceramic nanocomposite materials systems in which nanoscale scintillating crystallites are precipitated in a controlled manner from a transparent glass matrix. Precipitating crystallites in situ precludes nanoparticle agglomeration, and limiting crystallite size to 50 nm or less mitigates the effect of refractive index mismatch between the crystals and host glass. Cerium-doped gadolinium bromide (GdBr3(Ce)) scintillating crystals were incorporated into sodium-aluminosilicate (NAS) and alumino-borosilicate (ABS) host glass matrices, and the resulting glass-ceramic structures and luminescence behavior were characterized. The as-cast glass from the ABS system displayed a highly ordered microstructure that produced the highest luminescence intensity (light yield) of the samples studied. However, heat treating to form the glass-ceramic precipitated rare-earth oxide crystallites rather than rare-earth halides. This degraded light yield relative to the unaged sample.

  18. Glass Ceramic Formulation Data Package

    SciTech Connect

    Crum, Jarrod V.; Rodriguez, Carmen P.; McCloy, John S.; Vienna, John D.; Chung, Chul-Woo

    2012-06-17

    A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et al. 2007). A multi-phase glass ceramic waste form allows incorporation of insoluble components of the waste by designed crystallization into durable heat tolerant phases. The glass ceramic formulation and processing targets the formation of the following three stable crystalline phases: (1) powellite (XMoO4) where X can be (Ca, Sr, Ba, and/or Ln), (2) oxyapatite Yx,Z(10-x)Si6O26 where Y is alkaline earth, Z is Ln, and (3) lanthanide borosilicate (Ln5BSi2O13). These three phases incorporate the waste components that are above the solubility limit of a single-phase borosilicate glass. The glass ceramic is designed to be a single phase melt, just like a borosilicate glass, and then crystallize upon slow cooling to form the targeted phases. The slow cooling schedule is based on the centerline cooling profile of a 2 foot diameter canister such as the Hanford High-Level Waste canister. Up to this point, crucible testing has been used for glass ceramic development, with cold crucible induction melter (CCIM) targeted as the ultimate processing technology for the waste form. Idaho National Laboratory (INL) will conduct a scaled CCIM test in FY2012 with a glass ceramic to demonstrate the processing behavior. This Data Package documents the laboratory studies of the glass ceramic composition to support the CCIM test. Pacific Northwest National Laboratory (PNNL) measured melt viscosity, electrical conductivity, and crystallization behavior upon cooling to identify a processing window (temperature range) for melter operation and cooling profiles necessary to crystallize the targeted phases in the

  19. Volcanic glasses, their origins and alteration processes

    USGS Publications Warehouse

    Friedman, I.; Long, W.

    1984-01-01

    Natural glass can be formed by volcanic processes, lightning (fulgarites) burning coal, and by meteorite impact. By far the most common process is volcanic - basically the glass is rapidly chilled molten rock. All natural glasses are thermodynamically unstable and tend to alter chemically or to crystallize. The rate of these processes is determined by the chemical composition of the magma. The hot and fluid basaltic melts have a structure that allows for rapid crystal growth, and seldom forms glass selvages greater than a few centimeters thick, even when the melt is rapidly cooled by extrusion in the deep sea. In contrast the cooler and very viscous rhyolitic magmas can yield bodies of glass that are tens of meters thick. These highly polymerized magmas have a high silica content - often 71-77% SiO2. Their high viscosity inhibits diffusive crystal growth. Basalt glass in sea water forms an alteration zone called palagonite whose thickness increases linearly with time. The rate of diffusion of water into rhyolitic glass, which follows the relationship - thickness = k (time) 1 2, has been determined as a function of the glass composition and temperature. Increased SiO2 increases the rate, whereas increased CaO, MgO and H2O decrease the rate. The activation energy of water diffusion varies from about 19 to 22 kcal/mol. for the glasses studied. The diffusion of alkali out of rhyolite glass occurs simultaneously with water diffusion into the glass. The rate of devitrification of rhyolitic glass is a function of the glass viscosity, which in turn is a function of water content and temperature. Although all of the aforementioned processes tend to destroy natural glasses, the slow rates of these processes, particularly for rhyolitic glass, has allowed samples of glass to persist for 60 million years. ?? 1984.

  20. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, S.; Boehm, L.; Volin, K.J.; Delbecq, C.J.

    1982-05-06

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS/sub 2/, B/sub 2/S/sub 2/ and SiS/sub 2/ in mixture with a glass modifier such as Na/sub 2/S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1 - X) Na/sub 2/O:XB/sub 2/S/sub 3/ is disclosed.

  1. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, S.; Delbecq, C.J.; Volin, K.J.; Boehm, L.

    1984-02-21

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS[sub 2], B[sub 2]S[sub 3] and SiS[sub 2] in mixture with a glass modifier such as Na[sub 2]S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na[sub 2]O:XB[sub 2]S[sub 3] is disclosed. 4 figs.

  2. Quartz and feldspar glasses produced by natural and experimental shock.

    NASA Technical Reports Server (NTRS)

    Stoeffler, D.; Hornemann, U.

    1972-01-01

    Refractive index, density, and infrared absorption studies of naturally and experimentally shocked-produced glasses formed from quartz, plagioclase, and alkali-feldspar confirm the existence of two main groups of amorphous forms of the framework silicates: solid-state and liquid-state glasses. These were apparently formed as metastable release products of high-pressure-phases above and below the glass transition temperatures. Solid-state glasses exhibit a series of structural states with increasing disorder caused by increasing shock pressures and temperatures. They gradually merge into the structural state of fused minerals similar to that of synthetic glasses quenched from a melt. Shock-fused alkali feldspars can, however, be distinguished from their laboratory-fused counterparts by infrared absorption and by higher density.

  3. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, Sherman; Boehm, Leah; Volin, Kenneth J.; Delbacq, Charles J.

    1985-01-01

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS.sub.2, B.sub.2 S.sub.3 and SiS.sub.2 in mixture with a glass modifier such as Na.sub.2 S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na.sub.2 O:XB.sub.2 S.sub.3 is disclosed.

  4. Glass capable of ionic conduction and method of preparation

    DOEpatents

    Susman, Sherman; Delbecq, Charles J.; Volin, Kenneth J.; Boehm, Leah

    1984-01-01

    Sulfide glasses capable of conducting alkali metal ions are prepared from a nonmetal glass former such as GeS.sub.2, B.sub.2 S.sub.3 and SiS.sub.2 in mixture with a glass modifier such as Na.sub.2 S or another alkali metal sulfide. A molten mixture of the constituents is rapidly quenched to below the glass transition temperature by contact with a metal mold. The rapid quench is sufficient to prevent crystallization and permit solidification as an amorphous solid mixture. An oxygen-free atmosphere is maintained over the mixture to prevent oxidation. A new glass system of (1-X) Na.sub.2 O:XB.sub.2 S.sub.3 is disclosed.

  5. Determination of the Structure of Vitrified Hydroceramic/CBC Waste Form Glasses Manufactured from DOE Reprocessing Waste

    SciTech Connect

    Scheetz, B.E.; White, W. B.; Chesleigh, M.; Portanova, A.; Olanrewaju, J.

    2005-05-31

    The selection of a glass-making option for the solidification of nuclear waste has dominated DOE waste form programs since the early 1980's. Both West Valley and Savannah River are routinely manufacturing glass logs from the high level waste inventory in tank sludges. However, for some wastes, direct conversion to glass is clearly not the optimum strategy for immobilization. INEEL, for example, has approximately 4400 m{sup 3} of calcined high level waste with an activity that produces approximately 45 watts/m{sup 3}, a rather low concentration of radioactive constituents. For these wastes, there is value in seeking alternatives to glass. An alternative approach has been developed and the efficacy of the process demonstrated that offers a significant savings in both human health and safety exposures and also a lower cost relative to the vitrification option. The alternative approach utilizes the intrinsic chemical reactivity of the highly alkaline waste with the addition of aluminosilicate admixtures in the appropriate proportions to form zeolites. The process is one in which a chemically bonded ceramic is produced. The driving force for reaction is derived from the chemical system itself at very modest temperatures and yet forms predominantly crystalline phases. Because the chemically bonded ceramic requires an aqueous medium to serve as a vehicle for the chemical reaction, the proposed zeolite-containing waste form can more adequately be described as a hydroceramic. The hydrated crystalline materials are then subject to hot isostatic pressing (HIP) which partially melts the material to form a glass ceramic. The scientific advantages of the hydroceramic/CBC approach are: (1) Low temperature processing; (2) High waste loading and thus only modest volumetric bulking from the addition of admixtures; (3) Ability to immobilize sodium; (4) Ability to handle low levels of nitrate (2-3% NO{sub 3}{sup -}); (5) The flexibility of a vitrifiable waste; and (6) A process that

  6. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  7. Regenerable activated bauxite adsorbent alkali monitor probe

    SciTech Connect

    Lee, S.H.D.

    1991-01-22

    This invention relates to a regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor 5 concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC 10 exhaust gases.

  8. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  9. Chemical durability of simulated nuclear glasses containing water

    SciTech Connect

    Li, H.; Tomozawa, M.

    1995-04-01

    The chemical durability of simulated nuclear waste glasses having different water contents was studied. Results from the product consistency test (PCT) showed that glass dissolution increased with water content in the glass. This trend was not observed during MCC-1 testing. This difference was attributed to the differences in reactions between glass and water. In the PCT, the glass network dissolution controlled the elemental releases, and water in the glass accelerated the reaction rate. On the other hand, alkali ion exchange with hydronium played an important role in the MCC-1. For the latter, the amount of water introduced into a leached layer from ion-exchange was found to be much greater than that of initially incorporated water in the glass. Hence, the initial water content has no effect on glass dissolution as measured by the MCC-1 test.

  10. Crystallization kinetics of BaO-Al2O3-SiO2 glasses

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Hyatt, Mark J.

    1988-01-01

    Barium aluminosilicate glasses are being investigated as matrix materials in high-temperature ceramic composites for structural applications. Kinetics of crystallization of two refractory glass compositions in the barium aluminosilicate system were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). From variable heating rate DTA, the crystallization activation energies for glass compositions (wt percent) 10BaO-38Al2O3-51SiO2-1MoO3 (glass A) and 39BaO-25Al2O3-35SiO2-1MoO3 (glass B) were determined to be 553 and 558 kJ/mol, respectively. On thermal treatment, the crystalline phases in glasses A and B were identified as mullite (3Al2O3-2SiO2) and hexacelsian (BaO-Al2O3-2SiO2), respectively. Hexacelsian is a high-temperature polymorph which is metastable below 1590 C. It undergoes structural transformation into the orthorhombic form at approximately 300 C accompanied by a large volume change which is undesirable for structural applications. A process needs to be developed where stable monoclinic celsian, rather than hexacelsian, precipitates out as the crystal phase in glass B.

  11. Phonon spectra of alkali metals

    NASA Astrophysics Data System (ADS)

    Zeković, S.; Vukajlović, F.; Veljković, V.

    1982-10-01

    In this work we used a simple local model pseudopotential which includes screening for the phonon spectra calculations of alkali metals. The results obtained are in very good agreement with experimental data. In some branches of phonon spectra the differences between theoretical and experimental results are within 1-2%, while the maximum error is about 6%. The suggested form of the pseudopotential allows us to describe the phonon spectra of Na, K and Rb with only one, and, at the same time, a unique, parameter. In this case, the maximum disagreements from experiment are 9% for Na, 8% for K and 7% for Rb.

  12. Reported sulfate mineral in lunar meteorite PCA 02007 is impact glass

    NASA Astrophysics Data System (ADS)

    Gross, Juliane; Treiman, Allan H.; Harlow, George E.

    2017-01-01

    A grain of light-blue sulfate material was reported in the lunar highlands regolith meteorite PCA 02007 (Satterwhite and Righter 2013). Allocated grains of that material are, in fact, aluminosilicate glass with a chemical composition like that of the bulk meteorite and other lunar highlands regoliths. The calcium sulfate detected in PCA 02007 was likely a surface coating, and reasonably of Antarctic (not lunar) origin.

  13. Water Content of Lunar Alkali Fedlspar

    NASA Technical Reports Server (NTRS)

    Mills, R. D.; Simon, J. I.; Wang, J.; Alexander, C. M. O'D.; Hauri, E. H.

    2016-01-01

    Detection of indigenous hydrogen in a diversity of lunar materials, including volcanic glass, melt inclusions, apatite, and plagioclase suggests water may have played a role in the chemical differentiation of the Moon. Spectroscopic data from the Moon indicate a positive correlation between water and Th. Modeling of lunar magma ocean crystallization predicts a similar chemical differentiation with the highest levels of water in the K- and Th-rich melt residuum of the magma ocean (i.e. urKREEP). Until now, the only sample-based estimates of water content of KREEP-rich magmas come from measurements of OH, F, and Cl in lunar apatites, which suggest a water concentration of < 1 ppm in urKREEP. Using these data, predict that the bulk water content of the magma ocean would have <10 ppm. In contrast, estimate water contents of 320 ppm for the bulk Moon and 1.4 wt % for urKREEP from plagioclase in ferroan anorthosites. Results and interpretation: NanoSIMS data from granitic clasts from Apollo sample 15405,78 show that alkali feldspar, a common mineral in K-enriched rocks, can have approx. 20 ppm of water, which implies magmatic water contents of approx. 1 wt % in the high-silica magmas. This estimate is 2 to 3 orders of magnitude higher than that estimated from apatite in similar rocks. However, the Cl and F contents of apatite in chemically similar rocks suggest that these melts also had high Cl/F ratios, which leads to spuriously low water estimates from the apatite. We can only estimate the minimum water content of urKREEP (+ bulk Moon) from our alkali feldspar data because of the unknown amount of degassing that led to the formation of the granites. Assuming a reasonable 10 to 100 times enrichment of water from urKREEP into the granites produces an estimate of 100-1000 ppm of water for the urKREEP reservoir. Using the modeling of and the 100-1000 ppm of water in urKREEP suggests a minimum bulk silicate Moon water content between 2 and 20 ppm. However, hydrogen loss was

  14. Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Guo, Haiquan; Newlin, Katy N.

    2011-01-01

    Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their morphology, pore size distribution, physical and skeletal densities. The present study focuses on the synthesis of aluminosilicate aerogel from a variety of Boehmite (precursors as the Al source, and tetraethylorthosilicate (TEOS) as the Si source, and the influence of starting powder on pore structure and thermal stability.

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

    DTIC Science & Technology

    2011-02-01

    the surface because it contains no free electron spins and it features a lower adsorption energy than the bare glass, thus re- ducing the residence...in the cell interior and a fluctuating magnetic field gen- erated by the hydrogen nuclei of the paraffin material.3 The adsorption energy for alkali...FTIR spectra of tetracontane (green, top), FR-130 ( blue , middle), and pwMB (black, bottom), with the traces offset vertically for clarity. The

  16. Process for the disposal of alkali metals

    DOEpatents

    Lewis, Leroy C.

    1977-01-01

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

  17. Formation and structure of Langmuir-Blodgett films of organo-modified aluminosilicate with high surface coverage.

    PubMed

    Fujimori, Atsuhiro; Arai, Shuntaro; Kusaka, Jun-ichi; Kubota, Munehiro; Kurosaka, Kei-ichi

    2013-02-15

    We have developed an effective organo-modification method at the organic solvent/distilled water interface of natural aluminosilicate clay surfaces. We also investigated the molecular arrangement of organo-modified aluminosilicate with high surface coverage in Langmuir-Blodgett films (LB) by performing out-of-plane and in-plane X-ray diffraction (XRD) measurements. In addition, the surface morphology of mixed monolayers of organo-modified aluminosilicate and several biodegradable polymers (e.g., poly(L-lactide), PLLA) was also characterized by atomic force microscopy (AFM). The in-plane XRD results of multilayers of organo-modified aluminosilicate formed by the LB method indicate the formation of a two-dimensional lattice of hydrocarbons on the aluminosilicate surface. These hydrocarbons of organo-modified reagents packed hexagonal or orthorhombic in films. Based on our experimental findings, the LB technique enabled the formation of a densely packed organo-modified aluminosilicate monolayer at the water surface. Furthermore, for mixed monolayer systems comprising an organo-modified clay with high surface coverage and biodegradable polymers, a miscible surface was observed by AFM on a mesoscopic scale, whereas those with low surface coverage formed phase-separated structures.

  18. Surface and interface investigation of aluminosilicate biomaterial by the “in vivo” experiments

    NASA Astrophysics Data System (ADS)

    Oudadesse, H.; Derrien, A. C.; Martin, S.; Chaair, H.; Cathelineau, G.

    2008-11-01

    Porous mixtures of aluminosilicate/calcium phosphate have been studied for biomaterials applications. Aluminosilicates formed with an inorganic polymeric constitution present amorphous zeolites because of their 3D network structure and present the ability to link to bone matrix. Amorphous geopolymers of the potassium-poly(sialate)-nanopolymer type were synthesised at low temperature and studied for their use as potential biomaterials. They were mixed with 13% weight of calcium phosphate like biphasic hydroxyapatite and β-tricalcium phosphate. In this study, " in vivo" experiments were monitored to evaluate the biocompatibility, the surface and the interface behaviour of these composites when used as bone implants. Moreover, it has been demonstrated using histological and physicochemical studies that the developed materials exhibited a remarkable bone bonding when implanted in a rabbit's thighbone for a period of 1 month. The easy synthesis conditions (low temperature) of this composite and the fast intimate links with bone constitute an improvement of synthetic bone graft biomaterial.

  19. [Assessment of carcinogenic effect of aluminosilicate ceramic fibers produced in Poland. Animal experiments].

    PubMed

    Krajnow, A; Lao, I

    2000-01-01

    The effect of aluminosilicate ceramic fibres produced in Poland was assessed. The experiment was performed on two animal species: Wistar rats and BALB/C mice. The animals were administered intraperitoneally the studied fibres and krokidolit UICC--in doses of 25 and 5 mg and left for survival. All dead and sacrificed animals were examined histopathologically. Carcinogenic properties of ceramic aluminosilicate fibres were found to be rather weak. Only in 1 (2.5%) of 39 rats under study benign mesothelioma of tunica vagiualis testis was diagnosed. Peritoneal mesothelioma was found in none of 50 mice studied. For comparison the effect of krokidolit UICC was assessed. Krokidolit UICC is characterised by strong carcinogenic properties. It induced peritoneal mesothelioma in 43 mice (44.2%) and in 29 (80.5%) of 36 rats under study.

  20. Glass recycling

    SciTech Connect

    Dalmijn, W.L.; Houwelingen, J.A. van

    1995-12-31

    Glass recycling in the Netherlands has grown from 10,000 to 300,000 tonnes per annum. The various advantages and problems of the glass cycle with reference to the state of the art in the Netherlands is given. Special attention is given to new technologies for the automated sorting of cullet with detection systems. In Western Europe the recycling of glass has become a success story. Because of this, the percentage of glass cullet used in glass furnaces has increased. To meet the quality demands of the glass industry, automated sorting for the removal of stones, non-ferrous metals and other impurities had to be developed and incorporated in glass recycling plants. In Holland, Germany and other countries, the amount of glass collected has reached a level that color-sorting becomes necessary to avoid market saturation with mixed cullet. Recently, two systems for color-sorting have been developed and tested for the separation of bottles and cullet in the size range of 20--50 mm. With the increased capacity of the new glass recycling plants, 120,000--200,000 tpy, the quality systems have also to be improved and automated. These quality control systems are based on the automated sorting technology developed earlier for the glass recycling plants. The data obtained are automatically processed and printed. The sampling system and its relation to the theory of Gy will be described. Results of both developments in glass recycling plants will be described.

  1. Glass Artworks

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Several NASA technologies have played part in growth and cost containment of studio glass art, among them a foam type insulation developed to meet a need for lightweight material that would reduce flame spread in aircraft fire. Foam comes in several forms and is widely used by glass artists, chiefly as an insulator for the various types of ovens used in glass working. Another Spinoff is alumina crucibles to contain molten glass. Before alumina crucibles were used, glass tanks were made of firebrick which tended to erode under high temperatures and cause impurities; this not only improved quality but made the process more cost effective. One more NASA technology that found its way into glass art working is a material known as graphite board, a special form of graphite originally developed for rocket motor applications. This graphite is used to exact compound angles and creates molds for poured glass artworks of dramatic design.

  2. High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

    PubMed Central

    Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.

    2013-01-01

    Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573

  3. Inhomogeneous and homogeneous linewidths in Er 3+-doped chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Bigot, L.; Jurdyc, A.-M.; Jacquier, B.; Adam, J.-L.

    2003-10-01

    The erbium 4I 13/2- 4I 15/2 transition around 1.5 μm is of prim interest for telecommunications and depends on the erbium ions surrounding. In glasses, the broadening of a transition comes from two contributions: inhomogeneous (due to the disorder) and homogeneous (due to the electron phonon interaction) broadening. Resonant Fluorescence Line Narrowing (RFLN) is a useful tool to separate this two parameters. We will show in this paper that the 4I 13/2- 4I 15/2 transition in chalcogenide glass (GeGaSSb) presents a strong homogeneous character and a smaller inhomogeneous contribution compared to aluminosilicate and fluoride glasses. Consequences on gain saturation will also be discussed.

  4. One-step synthesis of hydrothermally stable mesoporous aluminosilicates with strong acidity

    NASA Astrophysics Data System (ADS)

    Yang, Dongjiang; Xu, Yao; Wu, Dong; Sun, Yuhan

    2008-09-01

    Using tetraethylorthosilicate (TEOS), polymethylhydrosiloxane (PMHS) and aluminium isopropoxide (AIP) as the reactants, through a one-step nonsurfactant route based on PMHS-TEOS-AIP co-polycondensation, hydrothermally stable mesoporous aluminosilicates with different Si/Al molar ratios were successfully prepared. All samples exclusively showed narrow pore size distribution centered at 3.6 nm. To assess the hydrothermal stability, samples were subjected to 100 °C distilled water for 300 h. The boiled mesoporous aluminosilicates have nearly the same N 2 adsorption-desorption isotherms and the same pore size distributions as those newly synthesized ones, indicating excellent hydrothermal stability. The 29Si MAS NMR spectra confirmed that PMHS and TEOS have jointly condensed and CH 3 groups have been introduced into the materials. The 27Al MAS NMR spectra indicated that Al atoms have been incorporated in the mesopore frameworks. The NH 3 temperature-programmed desorption showed strong acidity. Due to the existence of large amount of CH 3 groups, the mesoporous aluminosilicates obtained good hydrophobicity. Owing to the relatively large pore and the strong acidity provided by the uniform four-coordinated Al atoms, the excellent catalytic performance for 1,3,5-triisopropylbenzene cracking was acquired easily. The materials may be a profitable complement for the synthesis of solid acid catalysts.

  5. Impact Of Sodium Oxalate, Sodium Aluminosilicate, and Gibbsite/Boehmite on ARP Filter Performance

    SciTech Connect

    Poirier, M.; Burket, P.

    2015-11-01

    The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). Recently, the low filter flux through the ARP of approximately 5 gallons per minute has limited the rate at which radioactive liquid waste can be treated. Salt Batch 6 had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. SRR requested SRNL to conduct bench-scale filter tests to evaluate whether sodium oxalate, sodium aluminosilicate, or aluminum solids (i.e., gibbsite and boehmite) could be the cause of excessive fouling of the crossflow or secondary filter at ARP. The authors conducted the tests by preparing slurries containing 6.6 M sodium Salt Batch 6 supernate, 2.5 g MST/L slurry, and varying concentrations of sodium oxalate, sodium aluminosilicate, and aluminum solids, processing the slurry through a bench-scale filter unit that contains a crossflow primary filter and a dead-end secondary filter, and measuring filter flux and transmembrane pressure as a function of time. Among the conclusions drwn from this work are the following: (1) All of the tests showed some evidence of fouling the secondary filter. This fouling could be from fine particles passing through the crossflow filter. (2) The sodium oxalate-containing feeds behaved differently from the sodium aluminosilicate- and gibbsite/boehmite-containing feeds.

  6. Origins of saccharide-dependent hydration at aluminate, silicate, and aluminosilicate surfaces

    PubMed Central

    Smith, Benjamin J.; Rawal, Aditya; Funkhouser, Gary P.; Roberts, Lawrence R.; Gupta, Vijay; Israelachvili, Jacob N.; Chmelka, Bradley F.

    2011-01-01

    Sugar molecules adsorbed at hydrated inorganic oxide surfaces occur ubiquitously in nature and in technologically important materials and processes, including marine biomineralization, cement hydration, corrosion inhibition, bioadhesion, and bone resorption. Among these examples, surprisingly diverse hydration behaviors are observed for oxides in the presence of saccharides with closely related compositions and structures. Glucose, sucrose, and maltodextrin, for example, exhibit significant differences in their adsorption selectivities and alkaline reaction properties on hydrating aluminate, silicate, and aluminosilicate surfaces that are shown to be due to the molecular architectures of the saccharides. Solid-state 1H, 13C, 29Si, and 27Al nuclear magnetic resonance (NMR) spectroscopy measurements, including at very high magnetic fields (19 T), distinguish and quantify the different molecular species, their chemical transformations, and their site-specific adsorption on different aluminate and silicate moieties. Two-dimensional NMR results establish nonselective adsorption of glucose degradation products containing carboxylic acids on both hydrated silicates and aluminates. In contrast, sucrose adsorbs intact at hydrated silicate sites and selectively at anhydrous, but not hydrated, aluminate moieties. Quantitative surface force measurements establish that sucrose adsorbs strongly as multilayers on hydrated aluminosilicate surfaces. The molecular structures and physicochemical properties of the saccharides and their degradation species correlate well with their adsorption behaviors. The results explain the dramatically different effects that small amounts of different types of sugars have on the rates at which aluminate, silicate, and aluminosilicate species hydrate, with important implications for diverse materials and applications. PMID:21562207

  7. Structural and compositional heterogeneities in liquid aluminosilicate: insight from a grain structure model

    NASA Astrophysics Data System (ADS)

    Van Nguyen, Hong; Tran, Duong Thuy; Pham, Hung Khac

    2017-02-01

    Network structure as well as structural and compositional heterogeneities in aluminosilicate (Al2O3-2SiO2) under compression is investigated by analysis and visualization of simulation data. Structural and compositional heterogeneities are clarified through analysis of topology structure and size distribution of TO x -clusters ( T = Si, Al; x = 3, 4, 5, 6) as well as O T y -clusters ( y = 2, 3, 4). The TO x -cluster can be considered as TO x -grains. It appears that the structure of aluminosilicate is the mixture of TO x -grains with a different short-range order structure and this is the origin of structural heterogeneity. Regarding their composition, the OSi y - and OAl y -clusters can be considered as silica- and alumina-grains respectively, and the structure of aluminosilicate can thus be considered to be formed from silica- and alumina-grains. This results in compositional heterogeneity. Moreover, the degree of polymerization and polyamorphism as well as dynamic heterogeneity is also discussed in detail.

  8. Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation

    SciTech Connect

    Oji, L.N.; Fellinger, T.L.; Hobbs, D.T.; Badheka, N.P.; Wilmarth, W.R.

    2008-07-01

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing dissolved aluminate and silicate has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS. (authors)

  9. The effects of intrapleural injections of alumina and aluminosilicate (ceramic) fibres.

    PubMed

    Pigott, G H; Ishmael, J

    1992-04-01

    Groups of rats, 24 male and 24 female, approximately 8 weeks old, were dosed by a single intrapleural injection with a saline suspension of refractory alumina fibres (Saffil fibres ICI plc) either as manufactured or after extensive thermal ageing; or one of two aluminosilicate ('ceramic') fibres with different diameter distributions. Similar groups were dosed with a suspension of UICC chrysotile A asbestos or saline solution to serve as positive and negative controls respectively. Rats were maintained to 85% mortality and all decedents and terminal sacrifices were closely examined for the presence of mesothelioma. Malignant mesothelioma was diagnosed in ten rats, seven dosed with asbestos and three dosed with aluminosilicate fibre B. No mesothelioma was detected in any rat dosed with Saffil fibres or aluminosilicate fibre A or in negative controls. The results support the predicted inert nature of Saffil alumina fibres and provide further evidence for the importance of fibre dimension in the induction of mesothelioma. The implication of the results for inhalation exposures is discussed.

  10. The effects of intrapleural injections of alumina and aluminosilicate (ceramic) fibres.

    PubMed Central

    Pigott, G. H.; Ishmael, J.

    1992-01-01

    Groups of rats, 24 male and 24 female, approximately 8 weeks old, were dosed by a single intrapleural injection with a saline suspension of refractory alumina fibres (Saffil fibres ICI plc) either as manufactured or after extensive thermal ageing; or one of two aluminosilicate ('ceramic') fibres with different diameter distributions. Similar groups were dosed with a suspension of UICC chrysotile A asbestos or saline solution to serve as positive and negative controls respectively. Rats were maintained to 85% mortality and all decedents and terminal sacrifices were closely examined for the presence of mesothelioma. Malignant mesothelioma was diagnosed in ten rats, seven dosed with asbestos and three dosed with aluminosilicate fibre B. No mesothelioma was detected in any rat dosed with Saffil fibres or aluminosilicate fibre A or in negative controls. The results support the predicted inert nature of Saffil alumina fibres and provide further evidence for the importance of fibre dimension in the induction of mesothelioma. The implication of the results for inhalation exposures is discussed. PMID:1571274

  11. STUDIES OF POTENTIAL INHIBITORS OF SODIUM ALUMINOSILICATE SCALES IN HIGH-LEVEL WASTE EVAPORATION

    SciTech Connect

    Wilmarth, B; Lawrence Oji, L; Terri Fellinger, T; David Hobbs, D; Nilesh Badheka, N

    2008-02-27

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing aluminum and silicates has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS.

  12. Feed Preparation for Source of Alkali Melt Rate Tests

    SciTech Connect

    Stone, M. E.; Lambert, D. P.

    2005-02-26

    The purpose of the Source of Alkali testing was to prepare feed for melt rate testing in order to determine the maximum melt-rate for a series of batches where the alkali was increased from 0% Na{sub 2}O in the frit (low washed sludge) to 16% Na{sub 2}O in the frit (highly washed sludge). This document summarizes the feed preparation for the Source of Alkali melt rate testing. The Source of Alkali melt rate results will be issued in a separate report. Five batches of Sludge Receipt and Adjustment Tank (SRAT) product and four batches of Slurry Mix Evaporator (SME) product were produced to support Source of Alkali (SOA) melt rate testing. Sludge Batch 3 (SB3) simulant and frit 418 were used as targets for the 8% Na{sub 2}O baseline run. For the other four cases (0% Na{sub 2}O, 4% Na{sub 2}O, 12% Na{sub 2}O, and 16% Na{sub 2}O in frit), special sludge and frit preparations were necessary. The sludge preparations mimicked washing of the SB3 baseline composition, while frit adjustments consisted of increasing or decreasing Na and then re-normalizing the remaining frit components. For all batches, the target glass compositions were identical. The five SRAT products were prepared for testing in the dry fed melt-rate furnace and the four SME products were prepared for the Slurry-fed Melt-Rate Furnace (SMRF). At the same time, the impacts of washing on a baseline composition from a Chemical Process Cell (CPC) perspective could also be investigated. Five process simulations (0% Na{sub 2}O in frit, 4% Na{sub 2}O in frit, 8% Na{sub 2}O in frit or baseline, 12% Na{sub 2}O in frit, and 16% Na{sub 2}O in frit) were completed in three identical 4-L apparatus to produce the five SRAT products. The SRAT products were later dried and combined with the complementary frits to produce identical glass compositions. All five batches were produced with identical processing steps, including off-gas measurement using online gas chromatographs. Two slurry-fed melter feed batches, a 4% Na

  13. Preliminary report on a glass burial experiment in granite

    SciTech Connect

    Clark, D.E.; Zhu, B.F.; Robinson, R.S.; Wicks, G.G.

    1983-01-01

    Preliminary results of a two-year burial experiment in granite are discussed. Three compositions of simulated alkali borosilicate waste glasses were placed in boreholes approximately 350 meters deep. The glass sample configurations include mini-cans (stainless steel rings into which glass has been cast) and pineapple slices (thin sections from cylindrical blocks). Assemblies of these glass samples were prepared by stacking them together with granite, compacted bentonite and metal rings to provide several types of interfaces that are expected to occur in the repository. The assemblies were maintained at either ambient mine temperature (8 to 10/sup 0/C) or 90/sup 0/C. The glasses were analyzed before burial and after one month storage at 90/sup 0/C. The most extensive surface degradation occurred on the glasses interfaced with bentonite. In general, very little attack was observed on glass surfaces in contact with the other materials. The limited field and laboratory data are compared.

  14. Glass Research

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.

    1985-01-01

    Research efforts span three general areas of glass science: glass refining, gel-derived glasses, and nucleation and crystallization of glasses. Gas bubbles which are present in a glass product are defects which may render the glass totally useless for the end application. For example, optical glasses, laser host glasses, and a variety of other specialty glasses must be prepared virtually defect free to be employable. Since a major mechanism of bubble removal, buoyant rise, is virtually inoperative in microgravity, glass fining will be especially difficult in space. On the other hand, the suppression of buoyant rise and the ability to perform containerless melting experiments in space allows the opportunity to carry out several unique bubble experiments in space. Gas bubble dissolution studies may be performed at elevated temperatures for large bubbles with negligible bubble motion. Also, bubble nucleation studies may be performed without the disturbing feature of heterogeneous bubble nucleation at the platinum walls. Ground based research efforts are being performed in support of these potential flight experiments.

  15. XAS study of Cl and K speciation in glasses quenched from alkalic silicate and carbonate-silicate melts at high-pressure

    NASA Astrophysics Data System (ADS)

    Shiryaev, Andrei; Safonov, Oleg; Huthwelker, Thomas

    2010-05-01

    Data on microinclusions in kimberlitic diamonds and experimental results indicate that potassic Cl-bearing silicate and carbonate-silicate melts could be potential media for diamond nucleation and precursors of carbonatite-kimberlite magmatism in the Earth's mantle. These HP melts were presumably formed in equilibrium immiscible chloride or chloride-carbonate liquids [1, 2]. The immiscibility results from structural properties of the melts, in particular, from K and Cl speciation in them. We report preliminary results on X-ray absorption study of K and Cl local environments in the glasses quenched from melts in the systems NaAlSi2O6-KCl and CaMgSi2O6-CaCO3-Na2CO3-KCl at pressure 5 GPa. Experimental study of the system NaAlSi2O6-KCl [3] revealed a very strong shift of equilibrium between immiscible aluminosilicate and (K,Na)Cl melts NaAlSi2O6+ KCl = KAlSi2O6+ NaCl to the right, resulting in formation of the K-rich (up to 16 wt. % of K2O) aluminosilicate melt with 1.6-1.8 wt.% of Cl. It indicates active separation of K and Cl, which implies different structural positions of these ions in the aluminosilicate melt. Cl XAS spectra in most cases are fairly similar to the spectra of crystalline KCl with minor contribution of NaCl. Thus, chlorine is totally segregated into K(Na)Cl-like clusters of different sizes. K XAS spectra of the glasses could be represented as superposition of contributions from KCl and KAlSi3O8-NaAlSi3O8 glass [4]; the second component is dominant. Thus, in the glasses (and, presumably, in corresponding melts) K is predominantly bound to silicate units, represented by 4-membered rings as follows from Raman spectroscopy. Its CN is higher, than in crystalline leucite (>6). In contrast, Cl is coordinated exclusively by alkali ions in chloride clusters. System CaMgSi2O6-CaCO3-Na2CO3-KCl at 5 GPa shows a wide miscibility gap between Cl-bearing carbonate-silicate and Si-saturated chloride-carbonate melts [1], which converge with a decrease of the SiO2

  16. Glass recycling in cement production--an innovative approach.

    PubMed

    Chen, Guohua; Lee, Harry; Young, King Lun; Yue, Po Lock; Wong, Adolf; Tao, Thomas; Choi, Ka Keung

    2002-01-01

    An innovative approach of using waste glass in cement production was proposed and tested in a laboratory and cement production plant. The laboratory characterization of 32 types of glass show that the chemical composition of glass does not vary significantly with its color or origin but depends on its application. The alkali content of glass, a major concern for cement production varies from 0 to 22%. For the glass bottles mainly found in Hong Kong waste glasses, the alkali content (Na2O) ranges from 10 to 19% with an average around 15%. There is no significant change of the SO2 content in the gas exhaust of the rotary kiln when about 1.8 t/h of glass bottles were loaded along with the 280-290 t/h raw materials. The content of NOx, mainly depends on the temperature of the kiln, does not show significant change either. The SO3 content of the clinker is comparable with that obtained without the loading of glass. The alkaline content shows a slight increase but still within three times the standard deviation obtained from the statistical data of the past year. The detailed analysis of the quality of the cement product shows that there is not any significant impact of glass for the feeding rate tested.

  17. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Schmalzer, D.K.; Steindler, M.J.; Lee, S.H.D.; Swift, W.M.

    1992-12-01

    This project supports the DOE/METC Fossil Energy Program for the development of Pressurized fluidized bed combustion (PFBC) technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an alternative to the on-line alkali analyzer for field application. RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no high temperature/high pressure (HTHP) sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-reaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial-grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6{und M}-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed in the following.

  18. Measurement of alkali in PFBC exhaust

    SciTech Connect

    Schmalzer, D.K.; Steindler, M.J.; Lee, S.H.D.; Swift, W.M.

    1992-01-01

    This project supports the DOE/METC Fossil Energy Program for the development of Pressurized fluidized bed combustion (PFBC) technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an alternative to the on-line alkali analyzer for field application. RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no high temperature/high pressure (HTHP) sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-reaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial-grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6[und M]-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed in the following.

  19. Measurement of alkali in PFBC exhaust

    SciTech Connect

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

    1992-01-01

    This project supports the DOE/METC Fossil Energy Program for the development of PFBC technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an altemative to the on-line alkali analyzer for field application. As shown in Fig. 1, the RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no HTHP sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-leaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6M-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite [8]. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed.

  20. Measurement of alkali in PFBC exhaust

    SciTech Connect

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

    1992-11-01

    This project supports the DOE/METC Fossil Energy Program for the development of PFBC technology. Based on the analytical activated-bauxite sorber-bed technique, we are developing the RABSAM as an altemative to the on-line alkali analyzer for field application. As shown in Fig. 1, the RABSAM is a sampling probe containing a regenerable activated-bauxite adsorbent (RABA). It can be inserted directly into the PFBC exhaust duct and requires no HTHP sampling line. Alkali vapors are captured by the adsorbent purely through physical adsorption. The adsorbent is regenerated by a simple water-leaching process, which also recovers the adsorbed alkalis. The alkali analysis of the leachate by atomic absorption (AA) provides a basis for calculating the time-averaged alkali-vapor concentration in the PFBC exhaust. If the RABA is to use commercial grade activated bauxite, the clay impurities in activated bauxite can react with alkali vapors and, therefore, need to be either removed or deactivated. In earlier work, a 6M-LiCl-solution impregnation technique was shown to deactivate these impurities in fresh activated bauxite [8]. During this year, RABA prepared by this technique was tested in a pressurized alkali-vapor sorption test unit to determine its NaCl-vapor capture efficiency and the regenerability of the sorbent by water extraction. Results of this study are presented and discussed.

  1. Long-term product consistency test of simulated 90-19/Nd HLW glass

    NASA Astrophysics Data System (ADS)

    Gan, X. Y.; Zhang, Z. T.; Yuan, W. Y.; Wang, L.; Bai, Y.; Ma, H.

    2011-01-01

    Chemical durability of 90-19/Nd glass, a simulated high-level waste (HLW) glass in contact with the groundwater was investigated with a long-term product consistency test (PCT). Generally, it is difficult to observe the long term property of HLW glass due to the slow corrosion rate in a mild condition. In order to overcome this problem, increased contacting surface ( S/ V = 6000 m -1) and elevated temperature (150 °C) were employed to accelerate the glass corrosion evolution. The micro-morphological characteristics of the glass surface and the secondary minerals formed after the glass alteration were analyzed by SEM-EDS and XRD, and concentrations of elements in the leaching solution were determined by ICP-AES. In our experiments, two types of minerals, which have great impact on glass dissolution, were found to form on 90-19/Nd HLW glass surface when it was subjected to a long-term leaching in the groundwater. One is Mg-Fe-rich phyllosilicates with honeycomb structure; the other is aluminosilicates (zeolites). Mg and Fe in the leaching solution participated in the formation of phyllosilicates. The main components of phyllosilicates in alteration products of 90-19/Nd HLW glass are nontronite (Na 0.3Fe 2Si 4O 10(OH) 2·4H 2O) and montmorillonite (Ca 0.2(Al,Mg) 2Si 4O 10(OH) 2·4H 2O), and those of aluminosilicates are mordenite ((Na 2,K 2,Ca)Al 2Si 10O 24·7H 2O)) and clinoptilolite ((Na,K,Ca) 5Al 6Si 30O 72·18H 2O). Minerals like Ca(Mg)SO 4 and CaCO 3 with low solubility limits are prone to form precipitant on the glass surface. Appearance of the phyllosilicates and aluminosilicates result in the dissolution rate of 90-19/Nd HLW glass resumed, which is increased by several times over the stable rate. As further dissolution of the glass, both B and Na in the glass were found to leach out in borax form.

  2. Scintillating glass fiber-optic neutron sensors

    NASA Astrophysics Data System (ADS)

    Abel, K. H.; Arthur, R. J.; Bliss, M.

    1994-04-01

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers, which, as produced, typically have a transmission length (e(sup -1) length) of greater than 2 meters, are found to undergo aging when subjected to room air. The aging, which is complete in a few weeks, reduces the transmission length to the order of 0.5 meter. Because of the high alkali content of the glass (on the order of 20-30 mole percent lithia), we have attributed this aging to aqueous corrosion at the polymer cladding/glass interface. Changes in transmission with chemical treatment of the surface support the corrosion model. Fiber transmission performance has been preserved by modifying the hot-downdraw to a double crucible to produce glass-on-glass waveguides.

  3. Scintillating glass fiber-optic neutron sensors

    SciTech Connect

    Abel, K.H.; Arthur, R.J.; Bliss, M.

    1994-04-01

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers, which, as produced, typically have a transmission length (e{sup {minus}1} length) of greater than 2 meters, are found to undergo aging when subjected to room air. The aging, which is complete in a few weeks, reduces the transmission length to the order of 0.5 meter. Because of the high alkali content of the glass (on the order of 20--30 mole % lithia), we have attributed this aging to aqueous corrosion oat the polymer cladding/glass interface. changes in transmission with chemical treatment of the surface support the corrosion model. Fiber transmission performance has been preserved by modifying the hot-downdraw to a double crucible to produce glass-on-glass waveguides.

  4. The Impact of the Source of Alkali on Sludge Batch 3 Melt Rate (U)

    SciTech Connect

    Smith, M

    2005-04-01

    Previous Savannah River National Laboratory (SRNL) melt rate tests in support of the Defense Waste Processing Facility (DWPF) have indicated that improvements in melt rate can be achieved through an increase in the total alkali of the melter feed. Higher alkali can be attained by the use of an ''underwashed'' sludge, a high alkali frit, or a combination of the two. Although the general trend between melt rate and total alkali (in particular Na{sub 2}O content) has been demonstrated, the question of ''does the source of alkali (SOA) matter?'' still exists. Therefore the purpose of this set of tests was to determine if the source of alkali (frit versus sludge) can impact melt rate. The general test concept was to transition from a Na{sub 2}O-rich frit to a Na{sub 2}O-deficient frit while compensating the Na{sub 2}O content in the sludge to maintain the same overall Na{sub 2}O content in the melter feed. Specifically, the strategy was to vary the amount of alkali in frits and in the sludge batch 3 (SB3) sludge simulant (midpoint or baseline feed was SB3/Frit 418 at 35% waste loading) so that the resultant feeds had the same final glass composition when vitrified. A set of SOA feeds using frits ranging from 0 to 16 weight % Na{sub 2}O (in 4% increments) was first tested in the Melt Rate Furnace (MRF) to determine if indeed there was an impact. The dry-fed MRF tests indicated that if the alkali is too depleted from either the sludge (16% Na{sub 2}O feed) or the frit (the 0% Na{sub 2}O feed), then melt rate was negatively impacted when compared to the baseline SB3/Frit 418 feed currently being processed at DWPF. The MRF melt rates for the 4 and 12% SOA feeds were similar to the baseline SB3/Frit 418 (8% SOA) feed. Due to this finding, a smaller subset of SOA feeds that could be processed in the DWPF (4 and 12% SOA feeds) was then tested in the Slurry-fed Melt Rate Furnace (SMRF). The results from a previous SMRF test with SB3/Frit 418 (Smith et al. 2004) were used as the

  5. Effect of Network Modifying Cations on the Structural Disorder in Multi-Component Silicate Glasses

    NASA Astrophysics Data System (ADS)

    Sung, S.

    2005-12-01

    The structure of complex, multi-component silicate glasses and melts provides insight into the physiochemical properties (e.g. viscosity, diffusivity, and thermodynamic properties) of natural silicate melts. Particularly, quaternary aluminosilicate glasses are important as it covers compositions of slab driven melts at the convergent margin and, thus, yield constraints for the dynamics of magmas in the earth's interior. Despite this importance, the structure of CaO-Na2O-Al2O3-SiO2 (CNAS) glasses has not been well understood because of inherent disorder in glasses and melts (Lee et al., 2005, Am, Min. p 1393). Solid-state 17O triple quantum (3Q) MAS MNR has been effective in yielding unpresented resolutions among oxygen sites in the glasses over conventional 1D MAS NMR, allowing us to determine the structure of multi-component silicate glasses (Lee et al., 2005, Am, Min. p 1393, Stebbins and Xu, 1997, Nature, p 60). Here, we report the first 17O MAS and 3QMAS NMR spectra for CNAS glasses with varying the Ca/Na ([(CaO) x (Na2O) 1.5-x](Al2O3)0.5 (SiO2)6) ratios at static magnetic fields of 14.1 Tesla (600 MHz). 17O MAS spectra show bridging oxygen (BO) peaks and partially resolved non-bridging oxygen (NBO) peaks (Ca-NBO and mixed {Ca, Na}-NBO). NBO in Ca-aluminosilicate glass moves toward lower frequency with increasing the Na/Ca ratios due to the formation of mixed-{Ca, Na}-NBO. This result suggests that the chemical shielding of mixed {Ca, Na}-NBO peak increases with increasing Ca contents and there is a mixing between Ca and Na around NBO in the Ca-Na aluminosilicate glasses. 17O 3QMAS NMR spectra exhibit well resolved BO peaks and partially resolved Ca-NBO and mixed-{Ca, Na}-NBO peaks. The fraction of Ca-NBO decrease with increasing Na/Ca ratios while the fraction of BO appears to be invariant with Na/Ca ratios. These results imply that NBO interacts more severely with network modifying cations than BO does. Another inherent disorder in silicate glasses and melts

  6. Characterization of high cesium containing glass-bonded ceramic waste forms.

    SciTech Connect

    Lambregts, M. J.; Frank, S. M.

    2003-10-03

    High cesium containing glass-bonded ceramic waste form samples were prepared and characterized to identify possible cesium phases present in glass-bonded ceramic waste forms developed for the containment of fission product bearing salts. Major phases of the waste forms are sodalite and glass. A combination of powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and nuclear magnetic resonance spectroscopy (NMR) were used to study the multiphase nature of these waste forms. Cesium was found to be present in the higher loaded waste forms in a cesium aluminosilicate phase with an analcime structure and a 1:1 Si:Al ratio, a pollucite phase, and also in the glass phase. The glass phase contains the majority of the cesium at lower loadings, however some pollucite also remains. Cesium was not detected in the sodalite phase of any of the samples.

  7. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  8. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  9. Advancements in flowing diode pumped alkali lasers

    NASA Astrophysics Data System (ADS)

    Pitz, Greg A.; Stalnaker, Donald M.; Guild, Eric M.; Oliker, Benjamin Q.; Moran, Paul J.; Townsend, Steven W.; Hostutler, David A.

    2016-03-01

    Multiple variants of the Diode Pumped Alkali Laser (DPAL) have recently been demonstrated at the Air Force Research Laboratory (AFRL). Highlights of this ongoing research effort include: a) a 571W rubidium (Rb) based Master Oscillator Power Amplifier (MOPA) with a gain (2α) of 0.48 cm-1, b) a rubidium-cesium (Cs) Multi-Alkali Multi-Line (MAML) laser that simultaneously lases at both 795 nm and 895 nm, and c) a 1.5 kW resonantly pumped potassium (K) DPAL with a slope efficiency of 50%. The common factor among these experiments is the use of a flowing alkali test bed.

  10. Structure of rhenium-containing sodium borosilicate glass

    SciTech Connect

    Goel, Ashutosh; McCloy, John S.; Windisch, Charles F.; Riley, Brian J.; Schweiger, Michael J.; Rodriguez, Carmen P.; Ferreira, Jose M.

    2013-03-01

    A series of sodium borosilicate glasses were synthesized with increasing fractions of KReO4 or Re2O7, to 10000 ppm (1 mass%) target Re in glass, to assess the effects of large concentrations of rhenium on glass structure and to estimate the solubility of technetium, a radioactive component in typical low active waste nuclear waste glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy were performed to characterize the glasses as a function of Re source additions. In general, silicon was found coordinated in a mixture of Q2 and Q3 structural units, while Al was 4-coordinated and B was largely 3-coordinate and partially 4-coordinated. The rhenium source did not appear to have significant effects on the glass structure. Thus, at the up to the concentrations that remain in dissolved in glass, ~3000 ppm Re by mass maximum. , the Re appeared to be neither a glass-former nor a strong glass modifier., Rhenium likely exists in isolated ReO4- anions in the interstices of the glass network, as evidenced by the polarized Raman spectrum of the Re glass in the absence of sulfate. Analogous to SO42-¬ in similar glasses, ReO4- is likely a network modifier and forms alkali salt phases on the surface and in the bulk glass above solubility.

  11. Rb-Sr Isotopic Systematics of Alkali-Rich Fragments in the Yamato-74442 LL-Chondritic Breccia

    NASA Technical Reports Server (NTRS)

    Yokoyama, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simo, J. I.; Tappa, M. J.; Yoneda, S.

    2012-01-01

    Alkali-rich igneous fragments were identified in the brecciated LL-chondrites, Kr henberg (LL5)], Bhola (LL3-6) and Yamato (Y)-74442 (LL4), and show characteristic fractionation patterns of alkaline elements. The K-Rb-Cs-rich fragments in Kr henberg, Bhola, and Y-74442 are very similar in mineralogy and petrography (olivine + pyroxene + glass), suggesting that they could have come from related precursor materials. We have undertaken Rb-Sr isotopic studies on alkali-rich fragments in Y-74442 to precisely determine their crystallization ages and the isotopic signatures of their precursor material(s).

  12. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  13. Strength Improvement of Glass Substrates by Using Surface Nanostructures.

    PubMed

    Kumar, Amarendra; Kashyap, Kunal; Hou, Max T; Yeh, J Andrew

    2016-12-01

    Defects and heterogeneities degrade the strength of glass with different surface and subsurface properties. This study uses surface nanostructures to improve the bending strength of glass and investigates the effect of defects on three glass types. Borosilicate and aluminosilicate glasses with a higher defect density than fused silica exhibited 118 and 48 % improvement, respectively, in bending strength after surface nanostructure fabrication. Fused silica, exhibited limited strength improvement. Therefore, a 4-μm-deep square notch was fabricated to study the effect of a dominant defect in low defect density glass. The reduced bending strength of fused silica caused by artificial defect increased 65 % in the presence of 2-μm-deep nanostructures, and the fused silica regained its original strength when the nanostructures were 4 μm deep. In fragmentation tests, the fused silica specimen broke into two major portions because of the creation of artificial defects. The number of fragments increased when nanostructures were fabricated on the fused silica surface. Bending strength improvement and fragmentation test confirm the usability of this method for glasses with low defect densities when a dominant defect is present on the surface. Our findings indicate that nanostructure-based strengthening is suitable for all types of glasses irrespective of defect density, and the observed Weibull modulus enhancement confirms the reliability of this method.

  14. Thermochemical study of rare earth and nitrogen incorporation in glasses

    NASA Astrophysics Data System (ADS)

    Zhang, Yahong

    Rare earth containing aluminosilicate, borosilicate, aluminate and nitrogen containing aluminosilicate glasses are technically important materials. They have extraordinary physical and chemical properties such as high glass transition temperature, very low electrical conductivity, and excellent chemical stability. These unique properties lead to applications as coatings on metals and ceramics, optical fibers, semiconductors, and nuclear waste containment materials. In addition, such systems contain the most widely used additives for sintering of Si3N4, SiAlON and SiC ceramics for high temperature applications. Thermodynamic properties and the relations among energetics, structure and bonding are essential to controlling processing parameters to synthesize, at lower cost, materials having better properties. Earlier investigations mainly pertained to specific physical properties of rare-earth doped oxide and oxynitride glasses. Work on the thermodynamic stability and materials compatibility has been very sparse. High temperature solution calorimetry in molten oxide solvents is a powerful tool for the thermodynamic study of refractory materials. With implementation and improvement, this technique has been applied to the first measurement of enthalpies of formation of RE-Si-Al-O glasses, REAlO3 glasses, RE-Si-Al-O-N glasses, and Si3N 4 and Ge3N4 with high pressure spinel structure. The first successful synthesis of REAlO3 glasses has been achieved by containerless melting. Their large enthalpies of crystallization confirm that they are reluctant glass formers. For glasses along the 2REAlO3 -3SiO2 join, the strongly negative heats of mixing support the absence of miscibility gaps except possibly at very high silica content. Energetic evidence has been presented for incipient phase-ordered regions in Gd- or Hf-containing sodium alumino-borosilicate glasses for plutonium immobilization. Linear relations between enthalpies of formation of RESiAlON glasses from elements and

  15. Alkali basalts and enclosed ultramafic xenoliths near Ushuaia, Tierra Del Fuego, Argentina.

    PubMed

    Acevedo, Rogelio Daniel

    2016-01-01

    At the southernmost part of Tierra del Fuego a few outcrops and erratic boulders of alkali basaltic rocks with ultramafic enclaves have been studied. Alkali basalt plugs or pipes hitherto identified are scarce, and host rocks are constituted by slates that belong to Mesozoic deposition. The petrography, texture and composition of the basalt and xenoliths were investigated by petrographic microscope and electron microprobe analysis. Xenocrysts of amphibole and alkali feldspar, phenocrysts of nepheline, olivine, spinel, phlogopite and Fe-Ti minerals (10 %) and a diversity of xenoliths, mainly lherzolitic, pyroxenite and wehrlitic nodules (15 %), but also from metamorphic rocks provenance, are contained in the basalt groundmass (75 %). This finer-grained material is made up of laths or needles of plagioclase, pyroxene, opaque minerals, apatite and glass, with intersertal, hyalopilitic and pilotaxitic. Locally, rock has an even granoblastic texture. Former amygdules are filled by analcite, zeolites, sodalite and calcite. The normative classification, based on nepheline content, conclude that this rock is an alkali basalt. The chemical classification, considering immobile elements as Zr/TiO2 versus Nb/Y indicate an alkali basalt too and plots over the TAS diagram fall in the foidite (Na-rich or nephelinite) and basanite fields. The REE patterns are fractionated (La/Yb primitive mantle normalized is approximately 30). The K-Ar isotopic technique on individual macrocrysts gave ages of 146 ± 5 Ma (amphibole) and 127 ± 4 Ma (alkali feldspar); and K-Ar whole rock datum reported 8.3 ± 0.3 Ma. Nevertheless, fertile samples show geochemical features typical of deep derived material thus, based on the position in the actual tectonic setting, indicate that the basalt is older than its isotopic age.

  16. Improved alkali-metal/silicate binders

    NASA Technical Reports Server (NTRS)

    Schutt, J.

    1978-01-01

    Family of inorganic binders utilizes potassium or sodium oxide/silicate dispersion and employs high mole ratio of silicon dioxide to alkali-metal binder. Binders are stable, inexpensive, extremely water resistant, and easy to apply.

  17. Alkali Metal Handling Practices at NASA MSFC

    NASA Technical Reports Server (NTRS)

    Salvail, Patrick G.; Carter, Robert R.

    2002-01-01

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

  18. Alkali metal propellants for MPD thrusters

    NASA Technical Reports Server (NTRS)

    Polk, J. E.; Pivirotto, T. J.

    1991-01-01

    Experiments performed in the United States in the 1960s and early 1970s and in the Soviet Union with alkali metal-fuelled MPD thrusters indicate performance levels substantially better than those achieved with gaseous propellants. Cathode wear appears to be less in engines with alkali metal propellants also. A critical review of the available data indicates that the data are consistent and reliable. An analysis of testing and systems-level considerations shows that pumping requirements for testing are substantially decreased and reductions in tankage fraction can be expected. In addition, while care must be exercised in handling the alkali metals, it is not prohibitively difficult or hazardous. The greatest disadvantage seems to be the potential for spacecraft contamination, but there appear to be viable strategies for minimizing the impact of propellant deposition on spacecraft surfaces. Renewed examination of alkali metal-fuelled MPD thrusters for ambitious SEI missions is recommended.

  19. Desulfurizing Coal With an Alkali Treatment

    NASA Technical Reports Server (NTRS)

    Ravindram, M.; Kalvinskas, J. J.

    1987-01-01

    Experimental coal-desulfurization process uses alkalies and steam in fluidized-bed reactor. With highly volatile, high-sulfur bituminous coal, process removed 98 percent of pyritic sulfur and 47 percent of organic sulfur. Used in coal liquefaction and in production of clean solid fuels and synthetic liquid fuels. Nitrogen or steam flows through bed of coal in reactor. Alkalies react with sulfur, removing it from coal. Nitrogen flow fluidizes bed while heating or cooling; steam is fluidizing medium during reaction.

  20. A-thermal elastic behavior of silicate glasses

    NASA Astrophysics Data System (ADS)

    Rabia, Mohammed Kamel; Degioanni, Simon; Martinet, Christine; Le Brusq, Jacques; Champagnon, Bernard; Vouagner, Dominique

    2016-02-01

    Depending on the composition of silicate glasses, their elastic moduli can increase or decrease as function of the temperature. Studying the Brillouin frequency shift of these glasses versus temperature allows the a-thermal composition corresponding to an intermediate glass to be determined. In an intermediate glass, the elastic moduli are independent of the temperature over a large temperature range. For sodium alumino-silicate glasses, the a-thermal composition is close to the albite glass (NaAlSi3O8). The structural origin of this property is studied by in situ high temperature Raman scattering. The structure of the intermediate albite glass and of silica are compared at different temperatures between room temperature and 600 °C. When the temperature increases, it is shown that the high frequency shift of the main band at 440 cm-1 in silica is a consequence of the cristobalite-like alpha-beta transformation of 6-membered rings. This effect is stronger in silica than bond elongation (anharmonic effects). As a consequence, the elastic moduli of silica increase as the temperature increases. In the albite glass, the substitution of 25% of Si4+ ions by Al3+ and Na+ ions decreases the proportion of SiO2 6-membered rings responsible for the silica anomaly. The effects of the silica anomaly balance the anharmonicity in albite glass and give rise to an intermediate a-thermal glass. Different networks, formers or modifiers, can be added to produce different a-thermal glasses with useful mechanical or chemical properties.

  1. Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1982-September 1983

    SciTech Connect

    Lee, S.H.D.; Myles, K.M.; Jonke, A.A.

    1984-06-01

    Under the auspices of US Department of Energy, this work supports the program to develop sorbents for the cleanup of gases from pressurized fluidized-bed coal combustion (PFBC) so that these cleaned hot gases can be used to power downstream gas turbines without causing corrosion. A laboratory-scale pressurized test unit was used to continue the alkali-vapor characterization of activated bauxite and Emathlite at a bed temperature of 850/sup 0/C and a system pressure of 10 atm absolute in a simulated PFBC flue gas stream containing <10 ppMV NaCl vapor. Under the test conditions, preliminary results show a comparable NaCl-vapor capture capability for both activated bauxite and Emathlite. Emathlite was found to capture NaCl vapor essentially by chemical reactions with the vapor to form water-insoluble compounds, probably sodium aluminosilicates, whereas activated bauxite captures the vapor mainly by physical adsorption as sodium sulfate. The test unit was modified and tested to improve the control of NaCl vaporization in the unit required for the source of alkali vapor in the simulated flue gas. Experimental results are also presented on (1) water leachability of both metallic and nonmetallic ions present in activated bauxite when it is cyclically heat-treated in a simulated PFBC flue gas environment and then leached with distilled water, and (2) the effect of heat-treatment of Emathlite in the simulated PFBC flue gas on the changes of its physical and chemical properties.

  2. Recovery of alumina and alkali in Bayer red mud by the formation of andradite-grossular hydrogarnet in hydrothermal process.

    PubMed

    Zhang, Ran; Zheng, Shili; Ma, Shuhua; Zhang, Yi

    2011-05-30

    Bayer red mud (RM) is an alumina refinery waste product rich in aluminum oxides and alkalis which are present primarily in the form of sodium hydro-aluminosilicate desilication product (DSP). A hydrothermal process was employed to recover alumina and alkali from "Fe-rich" and "Fe-lean" RM, the two representative species of RM produced in China. The hydrothermal process objective phase is andradite-grossular hydrogarnet characterized by the isomorphic substitution of Al and Fe. Batch experiments were used to evaluate the main factors influencing the recovery process, namely reaction temperature, caustic ratio (molar ratio of Na(2)O to Al(2)O(3) in sodium solution), sodium concentration and residence time. The results revealed that the Na(2)O content of 0.5 wt% and A/S of 0.3 (mass ratio of Al(2)O(3) to SiO(2)) in leached residue could be achieved with Fe-rich RM under optimal conditions. However, the hydrothermal treatment of Fe-lean RM proved less successful unless the reaction system was enriched with iron. Subsequent experiments examined the effects of the ferric compound's content and type on the substitution ratio.

  3. Properties of glasses with high water content. Progress report, 1 March 1980-31 January 1981

    SciTech Connect

    Tomozawa, M.; Watson, E.B.

    1981-01-01

    Glasses with high water content were prepared by a hydrothermal process and various properties were measured. The following unique features have been revealed: (1) electrical conductivity decreases substantially at first with the addition of water and then increases with the further addition of water. The phenomenon is somewhat similar to the mixed alkali effect; (2) the glass with higher water content is radiation coloration resistant; (3) with the addition of water, glasses became tougher at room temperature, suggesting the occurrence of plastic deformation.

  4. Hardness and incipient plasticity in silicate glasses: Origin of the mixed modifier effect

    NASA Astrophysics Data System (ADS)

    Kjeldsen, Jonas; Smedskjaer, Morten M.; Mauro, John C.; Yue, Yuanzheng

    2014-02-01

    The scaling of Vickers hardness (Hv) in oxide glasses with varying network modifier/modifier ratio is manifested as either a positive or negative deviation from linearity with a maximum deviation at the ratio of about 1:1. In an earlier study [J. Kjeldsen et al., J. Non-Cryst. Solids 369, 61 (2013)], we observed a minimum of Hv in CaO/MgO sodium aluminosilicate glasses at CaO/MgO = 1:1 and postulated that this minimum is linked to a maximum in plastic flow. However, the origin of this link has not been experimentally verified. In this work, we attempt to do so by exploring the links among Hv, volume recovery ratio (VR) and plastic deformation volume (VP) under indentation, glass transition temperature (Tg), Young's modulus (E), and liquid fragility index (m) in CaO/MgO and CaO/Li2O sodium aluminosilicate glasses. We confirm the negative deviations from linearity and find that the maximum deviation (i.e., the so-called mixed modifier effect) of Hv, Tg, and m is at the modifier ratio of 1:1. These deviations increase in intensity as the total modifier concentration increases. We find a strong correlation between VP and Hv for the CaO/MgO series, implying that the minimum in Hv originates primarily from an increased shear flow in the mixed modifier glasses.

  5. High-Intensity Plasma Glass Melter Final Technical Report

    SciTech Connect

    Gonterman, J. Ronald; Weinstein, Michael A.

    2006-10-27

    frits. Exploratory melts of non-glassy materials, such as wollastonite, zirconium silicate, and alumino-silicate melts were successfully done indicating that plasma melting has potential application beyond glass. Experimental results were generated that show the high quality of plasma-melted fiberglass compositions, such as E-glass, can result in good fiberizing performance. Fiberizing performance and tensile strength data were achieved during the project to support this conclusion. High seed counts are a feature of the current lab scale melter and must be dealt with via other means, since fining work was outside the scope of this project.

  6. Microstructural changes induced by CO2 exposure in alkali-activated slag/metakaolin pastes

    NASA Astrophysics Data System (ADS)

    Bernal, Susan

    2016-09-01

    The structural changes induced by accelerated carbonation in alkali-activated slag/ metakaolin (MK) cements were determined. The specimens were carbonated for 540 h in an environmental chamber with a CO2 concentration of 1.0 ± 0.2%, a temperature of 20 ± 2ºC, and relative humidity of 65 ± 5 %. Accelerated carbonation led to decalcification of the main binding phase of these cements, which is an aluminium substituted calcium silicate hydrate (C-(N-)A-S-H) type gel, and the consequent formation of calcium carbonate. The sodium-rich carbonates trona (Na2CO3·NaHCO3·2H2O) and gaylussite (Na2Ca(CO3)2·5H2O) were identified in cements containing up to 10 wt.% MK as carbonation products. The formation of these carbonates is mainly associated with the chemical reaction between the CO2 and the free alkalis present in the pore solution. The structure of the carbonated cements is dominated by an aluminosilicate hydrate (N-A-S-H) type gel, independent of the MK content. The N-A-S-H type gels identified are likely to be derived both from the activation reaction of the MK, forming a low-calcium gel product which does not seem to undergo structural changes upon CO2 exposure, and the decalcification of C-(N-)A-S-H type gel. The carbonated pastes present a highly porous microstructure, more notable as the content of MK content in the cement increases, which might have a negative impact on the durability of these materials in service.

  7. Alkali-Activated Aluminium-Silicate Composites as Insulation Materials for Industrial Application

    NASA Astrophysics Data System (ADS)

    Dembovska, L.; Bajare, D.; Pundiene, I.; Bumanis, G.

    2015-11-01

    The article reports on the study of thermal stability of alkali-activated aluminium- silicate composites (ASC) at temperature 800-1100°C. ASC were prepared by using calcined kaolinite clay, aluminium scrap recycling waste, lead-silicate glass waste and quartz sand. As alkali activator, commercial sodium silicate solution modified with an addition of sodium hydroxide was used. The obtained alkali activation solution had silica modulus Ms=1.67. Components of aluminium scrap recycling waste (aluminium nitride (AlN) and iron sulphite (FeSO3)) react in the alkali media and create gases - ammonia and sulphur dioxide, which provide the porous structure of the material [1]. Changes in the chemical composition of ASC during heating were identified and quantitatively analysed by using DTA/TG, dimension changes during the heating process were determined by using HTOM, pore microstructure was examined by SEM, and mineralogical composition of ASC was determined by XRD. The density of ASC was measured in accordance with EN 1097-7. ASC with density around 560 kg/m3 and heat resistance up to 1100°C with shrinkage less than 5% were obtained. The intended use of this material is the application as an insulation material for industrial purposes at elevated temperatures.

  8. Mechanical and microstructural properties of alkali-activated fly ash geopolymers.

    PubMed

    Komljenović, M; Bascarević, Z; Bradić, V

    2010-09-15

    This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH)(2), NaOH, NaOH+Na(2)CO(3), KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 microm), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO(2)/Na(2)O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio.

  9. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete

    SciTech Connect

    Lu Duyou; Xu Zhongzi; Tang Mingshu; Fournier, Benoit

    2006-06-15

    Surface alteration of typical aggregates with alkali-silica reactivity and alkali-carbonate reactivity, i.e. Spratt limestone (SL) and Pittsburg dolomitic limestone (PL), were studied by XRD and SEM/EDS after autoclaving in KOH, NaOH and LiOH solutions at 150 deg. C for 150 h. The results indicate that: (1) NaOH shows the strongest attack on both ASR and ACR aggregates, the weakest attack is with LiOH. For both aggregates autoclaved in different alkali media, the crystalline degree, morphology and distribution of products are quite different. More crystalline products are formed on rock surfaces in KOH than that in NaOH solution, while almost no amorphous product is formed in LiOH solution; (2) in addition to dedolomitization of PL in KOH, NaOH and LiOH solutions, cryptocrystalline quartz in PL involves in reaction with alkaline solution and forms typical alkali-silica product in NaOH and KOH solutions, but forms lithium silicate (Li{sub 2}SiO{sub 3}) in LiOH solution; (3) in addition to massive alkali-silica product formed in SL autoclaved in different alkaline solutions, a small amount of dolomite existing in SL may simultaneously dedolomitize and possibly contribute to expansion; (4) it is promising to use the duplex effect of LiOH on ASR and ACR to distinguish the alkali-silica reactivity and alkali-carbonate reactivity of aggregate when both ASR and ACR might coexist.

  10. Use of recycled glass for concrete masonry blocks. Final report

    SciTech Connect

    Meyer, C.; Baxter, S.

    1997-11-01

    A two-year research project was conducted to study the technical and economic feasibility of using mixed-color crushed waste glass for concrete masonry. From a technical standpoint, two problems had to be confronted. First, it was known that the silica in glass is highly reactive in the alkaline environment of portland cement concrete. Second, there was the possibility of strength loss, as crushed glass particles with smooth surfaces were substituted for regular aggregate. Both problems were solved in the course of this research. It was found that waste glass ground to mesh size No. 30 or smaller does not exhibit any expansion due to alkali-silica reaction (ASR). Another significant research finding was that very finely ground glass exhibits pozzolanic properties and therefore is suitable as a partial replacement for portland cement. The economic feasibility of concrete block masonry with glass both as aggregate and cement substitution was evaluated and found to be encouraging.

  11. Contribution of Aluminas and Aluminosilicates to the Formation of PCDD/Fs on Fly Ashes

    PubMed Central

    Potter, Phillip M.; Dellinger, Barry; Lomnicki, Slawomir M.

    2015-01-01

    Chlorinated aromatics undergo surface-mediated reactions with metal oxides to form Environmentally Persistent Free Radicals (EPFRs) which can further react to produce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Previous work using laboratory-made fly ash surrogates composed of transition metal oxides deposited on silica powder has confirmed their ability to mimic fly ash in the production of PCDD/Fs. However, little is known about the propensity of aluminas and aluminosilicates, other components of fly ash, to form PCDD/Fs. A fly ash sample containing both alumina and mullite, an aluminosilicate, was tested for PCDD/F formation ability and compared to PCDD/F yields from the thermal degradation of 2-monochlorophenol (2-MCP) precursor over γ-alumina, α-alumina, and mullite. A packed-bed flow reactor was used to investigate the thermal degradation of 2-MCP over the various catalysts at 200–600 °C. Fly ash gave similar PCDD/F yields to surrogates made with similar transition metal content. γ-alumina, which is thermodynamically unfavorable, was very catalytically active and gave low PCDD/F yields despite a high destruction of 2-MCP. Mullite and α-alumina, the thermodynamically favorable form of alumina, yielded higher concentrations of dioxins and products with a higher degree of chlorine substitution than γ-alumina. The data suggest that certain aluminas and aluminosilicates, commonly found in fly ash, are active catalytic surfaces in the formation of PCDD/Fs in the post-flame cool zones of combustion systems and should be considered as additional catalytic surfaces active in the process. PMID:26615490

  12. In vitro osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement

    PubMed Central

    Eid, Ashraf A.; Niu, Li-na; Primus, Carolyn M.; Opperman, Lynne A.; Watanabe, Ikuya; Pashley, David H.; Tay, Franklin R.

    2013-01-01

    Introduction Calcium aluminosilicate cements are fast-setting, acid-resistant, bioactive cements that may be used as root-repair materials. This study examined the osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement (Quick-Set) using a murine odontoblast-like cell model. Methods Quick-Set and white ProRoot MTA (WMTA) were mixed with the proprietary gel or deionized water, allowed to set completely in 100% relative humidity and aged in complete growth medium for 2 weeks until rendered non-cytotoxic. Similarly-aged Teflon discs were used as negative control. The MDPC-23 cell-line was used for evaluating changes in mRNA expressions of genes associated with osteogenic/dentinogenic differentiation and mineralization (qRT-PCR) alkaline phosphatase enzyme production and extracellular matrix mineralization (Alizarin red-S staining). Results After MDPC-23 cells were incubated with the materials in osteogenic differentiation medium for 1 week, both cements showed upregulation in ALP and DSPP expression. Fold increases in these two genes were not significantly different between Quick-Set and WMTA. Both cements showed no statistically significant upregulation/downregulation in RUNX2, OCN, BSP and DMP1 gene expression compared with Teflon. Alkaline phosphatase activity of cells cultured on Quick-Set and WMTA were not significantly different at 1 week or 2 weeks, but were significantly higher (p<0.05) than Teflon in both weeks. Both cements showed significantly higher calcium deposition compared with Teflon after 3 weeks of incubation in mineralizing medium (p<0.001). Differences between Quick-Set and WMTA were not statistically significant. Conclusions The experimental calcium aluminosilicate cement exhibits similar osteogenic/dentinogenic properties to WMTA and may be a potential substitute for commercially-available tricalcium silicate cements. PMID:23953291

  13. Metallic nanoparticles and their medicinal potential. Part II: aluminosilicates, nanobiomagnets, quantum dots and cochleates.

    PubMed

    Loomba, Leena; Scarabelli, Tiziano

    2013-09-01

    Metallic miniaturization techniques have taken metals to nanoscale size where they can display fascinating properties and their potential applications in medicine. In recent years, metal nanoparticles such as aluminium, silicon, iron, cadmium, selenium, indium and calcium, which find their presence in aluminosilicates, nanobiomagnets, quantum dots (Q-dots) and cochleates, have caught attention of medical industries. The increasing impact of metallic nanoparticles in life sciences has significantly advanced the production techniques for these nanoparticles. In this Review, the various methods for the synthesis of nanoparticles are outlined, followed by their physicochemical properties, some recent applications in wound healing, diagnostic imaging, biosensing, assay labeling, antimicrobial activity, cancer therapy and drug delivery are listed, and finally their toxicological impacts are revised. The first half of this article describes the medicinal uses of two noble nanoparticles - gold and silver. This Review provides further information on the ability of aluminum, silicon, iron, selenium, indium, calcium and zinc to be used as nanoparticles in biomedical sciences. Aluminosilicates find their utility in wound healing and antibacterial growth. Iron-oxide nanoparticles enhance the properties of MRI contrast agents and are also used as biomagnets. Cadmium, selenium, tellurium and indium form the core nanostructures of tiny Q-dots used in cellular assay labeling, high-resolution cell imaging and biosensing. Cochleates have the bivalent nano ions calcium, magnesium or zinc imbedded in their structures and are considered to be highly effective agents for drug and gene delivery. The aluminosilicates, nanobiomagnets, Q-dots and cochleates are discussed in the light of their properties, synthesis and utility.

  14. Laser scanning confocal microscopy for in situ monitoring of alkali-silica reaction.

    PubMed

    Collins, C L; Ideker, J H; Kurtis, K E

    2004-02-01

    Alkali-silica reaction (ASR) occurs in concrete between reactive siliceous components in the aggregate and the strongly alkaline pore solution, resulting in the formation of a potentially expansive gel product. Lithium additives have been shown to reduce expansion associated with ASR, but the mechanism(s) by which lithium reduces expansion have not been understood. Therefore, development of an in situ method to observe reactions associated with ASR is highly desirable, as it will allow for non-destructive observation of the reaction product formation and damage evolution over time, as the reaction progresses. A technique to image into mortar through glass aggregate by laser scanning confocal microscopy (LSCM), producing three-dimensional representations of the sample was developed. This LSCM technique was utilized to monitor the progress of alkali-silica reaction in mortar samples prepared with alkali-reactive glass aggregate both in the presence and in the absence of lithium additives: LiNO3, LiCl or LiOH. The method proved to be effective in qualitatively monitoring crack formation and growth and product formation, within cracks and at the paste/aggregate interface. In particular, dendritic products were observed at the paste/aggregate interface only in those samples containing lithium, suggesting that these products may play a role in ASR mitigation.

  15. Viscosity properties of sodium borophosphate glasses

    SciTech Connect

    Gaylord, S.; Tincher, B.; Petit, L. Richardson, K.

    2009-05-06

    The viscosity behavior of (1 - x)NaPO{sub 3}-xNa{sub 2}B{sub 4}O{sub 7} glasses (x = 0.05-0.20) have been measured as a function of temperature using beam-bending and parallel-plate viscometry. The viscosity was found to shift to higher temperatures with increasing sodium borate content. The kinetic fragility parameter, m, estimated from the viscosity curve, decreases from 52 to 33 when x increases from 0.05 to 0.20 indicating that the glass network transforms from fragile to strong with the addition of Na{sub 2}B{sub 4}O{sub 7}. The decrease in fragility with increasing x is due to the progressive depolymerization of the phosphate network by the preferred four-coordinated boron atoms present in the low alkali borate glasses. As confirmed by Raman spectroscopy increasing alkali borate leads to enhanced B-O-P linkages realized with the accompanying transition from solely four-coordinated boron (in BO{sub 4} units) to mixed BO{sub 4}/BO{sub 3} structures. The glass viscosity characteristics of the investigated glasses were compared to those of P-SF67 and N-FK5 commercial glasses from SCHOTT. We showed that the dependence of the viscosity of P-SF67 was similar to the investigated glasses due to similar phosphate network organization confirmed by Raman spectroscopy, whereas N-FK5 exhibited a very different viscosity curve and fragility parameter due to its highly coordinated silicate network.

  16. Dynamics of Oxidation of a Fe2+-Bearing Aluminosilicate (Basaltic) Melt

    PubMed

    Cooper; Fanselow; Weber; Merkley; Poker

    1996-11-15

    Rutherford backscattering spectroscopy (RBS) and microscopy demonstrate that the approximately 1400°C oxidation of levitated droplets of a natural Fe2+-bearing aluminosilicate (basalt) melt occurs by chemical diffusion of Fe2+ and Ca2+ to the free surface of the droplet; internal oxidation of the melt results from the required counterflux of electron holes. Diffusion of an oxygen species is not required. Oxidation causes the droplets to go subsolidus; magnetite (Fe3O4) forms at the oxidation-solidification front with a morphology suggestive of a Liesegang-band nucleation process.

  17. Physical chemical studies of dispersed aluminosilicate wastes for obtaining the burned building materials

    NASA Astrophysics Data System (ADS)

    Iuriev, I. Y.; Skripnikova, N. K.; Volokitin, G. G.; Volokitin, O. G.; Lutsenko, A. V.; Kosmachev, P. V.

    2015-01-01

    This paper presents results of the studies that determined that grinding can be one of the ways to modify aluminosilicate wastes. The optimal grinding modes were defined in laboratory conditions. Physical and chemical studies of modified ashes were carried out by means of X-ray phase analysis, differential thermal analysis and microscopy. The results have shown that modified ashes of thermal power stations when being applied in production of ceramic brick influence positively the processing properties of raw materials and the ready products.

  18. Potential Sites for Ice Nucleation on Aluminosilicate Clay Minerals and Related Materials.

    PubMed

    Freedman, Miriam Arak

    2015-10-01

    Few aerosol particles in clouds nucleate the formation of ice. The surface sites available for nucleus formation, which can include surface defects and functional groups, determine in part the activity of an aerosol particle toward ice formation. Although ice nucleation on particles has been widely studied, exploration of the specific sites at which the initial germ forms has been limited, but is important for predicting the microphysical properties of clouds, which impact climate. This Perspective focuses on what is currently known about surface sites for ice nucleation on aluminosilicate clay minerals, which are commonly found in ice residuals, as well as related materials.

  19. Triple stack glass-to-glass anodic bonding for optogalvanic spectroscopy cells with electrical feedthroughs

    SciTech Connect

    Daschner, R.; Kübler, H.; Löw, R.; Pfau, T.; Baur, H.; Frühauf, N.

    2014-07-28

    We demonstrate the use of an anodic bonding technique for building a vacuum tight vapor cell for the use of Rydberg spectroscopy of alkali atoms with thin film electrodes on the inside of the cell. The cell is fabricated by simultaneous triple stack glass-to-glass anodic bonding at 300 °C. This glue-free, low temperature sealing technique provides the opportunity to include thin film electric feedthroughs. The pressure broadening is only limited by the vapor pressure of rubidium and the lifetime is at least four months with operating temperatures up to 230 °C.

  20. Ultrasonic microspectroscopy characterization of chemically tempered glass

    NASA Astrophysics Data System (ADS)

    Arakawa, Mototaka; Kushibiki, Jun-ichi; Ohashi, Yuji

    2017-01-01

    We evaluated the elastic properties of the compressive stress (CS) layer of chemically tempered glass by ultrasonic microspectroscopy (UMS) in a very high frequency (VHF) range. Two commercial aluminosilicate glass specimens were prepared, and one of them was chemically tempered. Changes in elastic properties in the CS layer with the residual stress introduced by the exchange of Na+ ions for larger K+ ions were estimated by precisely measuring the densities and longitudinal and shear velocities for both the tempered and nontempered specimens. Using a single-layer model for the surface layer, we observed drastic increases in bulk-wave velocities and significant decreases in attenuation coefficients. We determined that the average elastic properties, namely, the elastic constants c 11 and c 44, and the density of the surface layer, were 9.6 and 7.1, and 1.2% larger than those of the nontempered specimen, respectively. We also estimated the distributions of the elastic properties according to the complementary error function (CEF) for the distribution of K+ ion concentration. Furthermore, using a line-focus-beam (LFB) system, we measured the frequency characteristics of the velocity (V LSAW) of leaky surface acoustic waves (LSAWs) on a water-loaded surface of the tempered specimen and clarified that the distributions of the elastic properties did not follow the CEF. The LFB system can be used for analyzing/determining details of the surface properties and is a promising tool for evaluating and characterizing chemically tempered glass and tempering process conditions.

  1. GLASS FIBER REINFORCED PLASTICS,

    DTIC Science & Technology

    Contents: Fibrous glass fillers Binders used in the glass plastic industry Method of manufacturing glass plastics and glass plastic articles Properties of fiberglass Primary areas for use of glass fibre reinforced plastics

  2. Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

    SciTech Connect

    ALAM,TODD M.

    1999-12-21

    Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.

  3. Topological principles of borosilicate glass chemistry.

    PubMed

    Smedskjaer, Morten M; Mauro, John C; Youngman, Randall E; Hogue, Carrie L; Potuzak, Marcel; Yue, Yuanzheng

    2011-11-10

    Borosilicate glasses display a rich complexity of chemical behavior depending on the details of their composition and thermal history. Noted for their high chemical durability and thermal shock resistance, borosilicate glasses have found a variety of important uses from common household and laboratory glassware to high-tech applications such as liquid crystal displays. In this paper, we investigate the topological principles of borosilicate glass chemistry covering the extremes from pure borate to pure silicate end members. Based on NMR measurements, we present a two-state statistical mechanical model of boron speciation in which addition of network modifiers leads to a competition between the formation of nonbridging oxygen and the conversion of boron from trigonal to tetrahedral configuration. Using this model, we derive a detailed topological representation of alkali-alkaline earth-borosilicate glasses that enables the accurate prediction of properties such as glass transition temperature, liquid fragility, and hardness. The modeling approach enables an understanding of the microscopic mechanisms governing macroscopic properties. The implications of the glass topology are discussed in terms of both the temperature and thermal history dependence of the atomic bond constraints and the influence on relaxation behavior. We also observe a nonlinear evolution of the jump in isobaric heat capacity at the glass transition when substituting SiO(2) for B(2)O(3), which can be accurately predicted using a combined topological and thermodynamic modeling approach.

  4. Tempered glass

    SciTech Connect

    Bunnell, L.R.

    1991-11-01

    This document describes a demonstration for making tempered glass using minimal equipment. The demonstration is intended for a typical student of materials science, at the high school level or above. (JL)

  5. Laboratory testing of glasses for Lockheed Idaho Technology Company: Final report

    SciTech Connect

    Ellison, A.J.G.; Buck, E.C.; Dietz, N.L.; Ebert, W.L.; Luo, J.S.; Wolf, S.F.; Bates, J.K.

    1997-06-01

    Tests have been conducted at Argonne National Laboratory (ANL) in support of the efforts of Lockheed Idaho Technology Company (LITCO) to vitrify high-level waste calcines. Tests were conducted with three classes of LITCO glass formulations: Formula 127 (fluorine-bearing), Formula 532 (fluorine-free), and 630 series (both single- and mixed-alkali) glasses. The test matrices included, as appropriate, the Product Consistency Test Method B (PCT-B), the Materials Characterization Center Test 1 (MCC-1), and the Argonne vapor hydration test (VHT). Test durations ranged from 7 to 183 d. In 7-d PCT-Bs, normalized mass losses of major glass-forming elements for the LITCO glasses are similar to, or lower than, normalized mass losses obtained for other domestic candidate waste glasses. Formula 532 glasses form zeolite alteration phases relatively early in their reaction with water. The formation of those phases increased the dissolution rate. In contrast, the Formula 127 glass is highly durable and forms alteration phases only after prolonged exposure to water in tests with very high surface area to volume ratios; these alteration phases have a relatively small effect on the rate of glass corrosion. No alteration phases formed within the maximum test duration of 183 d in PCT-Bs with the 630 series glasses. The corrosion behavior of the mixed-alkali 630 series glasses is similar to that of 630 series glasses containing sodium alone. In VHTs, both single- and mixed-alkali glasses form zeolite phases that increase the rate of glass reaction. The original 630 series glasses and those based on a revised surrogate calcine formulation react at the same rate in PCT-Bs and form the same major alteration phases in VHTs.

  6. Impurity detection in alkali-metal vapor cells via nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Patton, B.; Ishikawa, K.

    2016-11-01

    We use nuclear magnetic resonance spectroscopy of alkali metals sealed in glass vapor cells to perform in situ identification of chemical contaminants. The alkali Knight shift varies with the concentration of the impurity, which in turn varies with temperature as the alloy composition changes along the liquidus curve. Intentional addition of a known impurity validates this approach and reveals that sodium is often an intrinsic contaminant in cells filled with distilled, high-purity rubidium or cesium. Measurements of the Knight shift of the binary Rb-Na alloy confirm prior measurements of the shift's linear dependence on Na concentration, but similar measurements for the Cs-Na system demonstrate an unexpected nonlinear dependence of the Knight shift on the molar ratio. This non-destructive approach allows monitoring and quantification of ongoing chemical processes within the kind of vapor cells which form the basis for precise sensors and atomic frequency standards.

  7. Conversion of Nuclear Waste to Molten Glass: Cold-Cap Reactions in Crucible Tests

    DOE PAGES

    Xu, Kai; Hrma, Pavel; Rice, Jarrett A.; ...

    2016-05-23

    The feed-to-glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold cap during nuclear waste vitrification. Here, to investigate the conversion process, we analyzed heat-treated samples of a simulated high-level waste feed using X-ray diffraction, electron probe microanalysis, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700°C before the emerging glass-forming melt was completely connected. Above 700°C, intermediate aluminosilicate phases and quartz particles gradually dissolved in the continuous borosilicate melt, which expanded with transient foam. Finally, knowledge of the chemistry and physics of feed-to-glass conversion willmore » help us control the conversion path by changing the melter feed makeup to maximize the glass production rate.« less

  8. Corrosion behavior of a glass-bonded sodalite ceramic waste form and its constituents.

    SciTech Connect

    Lewis, M. A.; Ebert, W. L.; Morss, L.

    1999-06-18

    A ceramic waste form (CWF) of glass bonded sodalite is being developed as a waste form for the long-term immobilization of fission products and transuranic elements from the U.S. Department of Energy's activities on spent nuclear fuel conditioning. A durable waste form was prepared by hot isostatic pressing (HIP) a mixture of salt-loaded zeolite powders and glass frit. During HIP the zeolite is converted to sodalite, and the resultant CWF is been completed for durations of up to 182 days. Four dissolution modes were identified: dissolution of free salt, dissolution of the aluminosilicate matrix of sodalite and the accompanying dissolution of occluded salt, dissolution of the boroaluminosilicate matrix of the glass, and ion exchange. Synergies inherent to the CWF were identified by comparing the results of the tests with pure glass and sodalite with those of the composite CWF.

  9. Conversion of Nuclear Waste to Molten Glass: Cold-Cap Reactions in Crucible Tests

    SciTech Connect

    Xu, Kai; Hrma, Pavel; Rice, Jarrett A.; Schweiger, Michael J.; Riley, Brian J.; Overman, Nicole R.; Kruger, Albert A.

    2016-05-23

    The feed-to-glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold cap during nuclear waste vitrification. Here, to investigate the conversion process, we analyzed heat-treated samples of a simulated high-level waste feed using X-ray diffraction, electron probe microanalysis, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700°C before the emerging glass-forming melt was completely connected. Above 700°C, intermediate aluminosilicate phases and quartz particles gradually dissolved in the continuous borosilicate melt, which expanded with transient foam. Finally, knowledge of the chemistry and physics of feed-to-glass conversion will help us control the conversion path by changing the melter feed makeup to maximize the glass production rate.

  10. Effect of aluminosilicates and bentonite on aflatoxin-induced developmental toxicity in rat.

    PubMed

    Abdel-Wahhab, M A; Nada, S A; Amra, H A

    1999-01-01

    Numerous studies have established that aflatoxin is a potent developmental toxin in animals. Previous research has demonstrated that a phyllosilicate clay, hydrated sodium calcium aluminosilicate (HSCAS or Novasil), tightly binds and immobilizes aflatoxins in the gastrointestinal tract of animals and markedly reduces the bioavailability and toxicity of aflatoxin. Our objective in this study was to utilize the pregnant rat as an in vivo model to compare the potential of HSCAS and bentonite to prevent the developmental toxicity of aflatoxin. Aluminosilicates (HSCAS) and bentonite were added to the diet at a level of 0.5% (w/w) and fed to the pregnant rat throughout pregnancy (i.e. days 0-20). Test animals were fed an aflatoxin-contaminated diet (2.5 mg kg(-1) diet) with or without sorbents during gestation days 6-15. Evaluations of toxicity were performed on day 20. These included maternal (mortality, body weights, feed intake and litter weights), developmental (embryonic resorptions and fetal body weights) and biochemical (ALT, AST and AP) evaluations. Sorbents alone were not toxic and aflatoxin alone resulted in significant maternal and developmental toxicity. Animals treated with phyllosilicate (plus aflatoxin) were comparable to controls following evaluations for resorptions, live fetuses and fetal body weights, as well as biochemical parameters. While bentonite plus aflatoxin resulted in significant reduction in fetal body weight, none of the fetuses from HSCAS or bentonite plus aflatoxin-treated groups had any gross, internal soft tissue or major skeletal malformations.

  11. Fate of Uranium during Sodium Aluminosilicate Formation under Waste Tank Conditions

    SciTech Connect

    Wilmarth, B

    2005-06-22

    Experiments have been conducted to examine the fate of uranium during the formation of sodium aluminosilicate (NAS) when wastes containing high aluminate concentrations are mixed with wastes of high silicate concentration. Testing was conducted at varying degrees of uranium saturation. Testing examined typical tank conditions, e.g., stagnant, slightly elevated temperature (50 C). The results showed that under sub-saturated conditions uranium is not removed from solution to any large extent in both simulant testing and actual tank waste testing. There are data supporting a small removal due to sorption of uranium on sites in the NAS. Above the solubility limit the data are clear that a reduction in uranium concentration occurs with the formation of aluminosilicate. This uranium precipitation is fairly rapid and ceases when uranium reaches its solubility limit. At the solubility limit, it appears that uranium is not affected, but further testing might be warranted. Lastly, analysis of the uranium speciation in a Tank 49H set of samples showed the uranium to be soluble. Analysis of the solution composition and subsequent use of the Hobb's uranium solubility model indicated a uranium solubility limit of 32 mg/L. The measured value of uranium in the Tank 49H matched the model prediction.

  12. Aqueous dissolution, solubilities and thermodynamic stabilities of common aluminosilicate clay minerals: Kaolinite and smectites

    USGS Publications Warehouse

    May, Howard M.; Klnniburgh, D.G.; Helmke, P.A.; Jackson, M.L.

    1986-01-01

    Determinations of the aqueous solubilities of kaolinite at pH 4, and of five smectite minerals in suspensions set between pH 5 and 8, were undertaken with mineral suspensions adjusted to approach equilibrium from over- and undersaturation. After 1,237 days, Dry Branch, Georgia kaolinite suspensions attained equilibrium solubility with respect to the kaolinite, for which Keq = (2.72 ?? 0.35) ?? 107. The experimentally determined Gibbs free energy of formation (??Gf,2980) for the kaolinite is -3,789.51 ?? 6.60 kj mol-1. Equilibrium solubilities could not be determined for the smectites because the composition of the solution phase in the smectite suspensions appeared to be controlled by the formation of gibbsite or amorphous aluminum hydroxide and not by the smectites, preventing attempts to determine valid ??Gf0 values for these complex aluminosilicate clay minerals. Reported solubility-based ??Gf0 determinations for smectites and other variable composition aluminosilicate clay minerals are shown to be invalid because of experimental deficiencies and of conceptual flaws arising from the nature of the minerals themselves. Because of the variable composition of smectites and similar minerals, it is concluded that reliable equilibrium solubilities and solubility-derived ??Gf0 values can neither be rigorously determined by conventional experimental procedures, nor applied in equilibriabased models of smectite-water interactions. ?? 1986.

  13. Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

    SciTech Connect

    Myers, Rupert J.; L'Hôpital, Emilie; Provis, John L.; Lothenbach, Barbara

    2015-02-15

    There exists limited information regarding the effect of temperature on the structure and solubility of calcium aluminosilicate hydrate (C–A–S–H). Here, calcium (alumino)silicate hydrate (C–(A–)S–H) is synthesised at Ca/Si = 1, Al/Si ≤ 0.15 and equilibrated at 7–80 °C. These systems increase in phase-purity, long-range order, and degree of polymerisation of C–(A–)S–H chains at higher temperatures; the most highly polymerised, crystalline and cross-linked C–(A–)S–H product is formed at Al/Si = 0.1 and 80 °C. Solubility products for C–(A–)S–H were calculated via determination of the solid-phase compositions and measurements of the concentrations of dissolved species in contact with the solid products, and show that the solubilities of C–(A–)S–H change slightly, within the experimental uncertainty, as a function of Al/Si ratio and temperature between 7 °C and 80 °C. These results are important in the development of thermodynamic models for C–(A–)S–H to enable accurate thermodynamic modelling of cement-based materials.

  14. Removal of ammonia nitrogen from distilled old landfill leachate by adsorption on raw and modified aluminosilicate.

    PubMed

    Couto, Rafael Schirmer de Paula; Oliveira, Aline Faria; Guarino, Alcides Wagner Serpa; Perez, Daniel Vidal; Marques, Mônica Regina da Costa

    2017-04-01

    This study aimed to evaluate the ammonia-nitrogen removal by aluminosilicates, using both standard solutions as pretreated landfill leachate. Three types of commercial clays and one commercial zeolite were initially tested using standard solution; however, only one clay with the best removability and the zeolite were tested with pretreated leachate. The chosen clay sorption capacity with the standard solution reached 83%, while with the pretreated leachate solution has reached 95% and zeolites have reached, respectively, a removal of 73% and 81%. For this two adsorbents' studies of equilibrium and kinetic of the sorption were also performed. The Langmuir model was more adequate to describe the ion exchange equilibrium and the sorption mechanism fit the pseudo-second-order kinetic model. Moreover, the pretreatment used on leachate proved to be essential not only for ammonium detection in solution, but also to facilitate its sorption in aluminosilicates. This alternative of ammonia-nitrogen removal also generates a product derived from treatment that can be used as agricultural feedstock in the form of fertilizer.

  15. Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun

    2011-08-30

    Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production.

  16. Low melting high lithia glass compositions and methods

    DOEpatents

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2000-01-01

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  17. Low melting high lithia glass compositions and methods

    DOEpatents

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2004-11-02

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  18. Low melting high lithia glass compositions and methods

    DOEpatents

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2003-10-07

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  19. Structures and optical properties of tellurite glasses and glass ceramics

    NASA Astrophysics Data System (ADS)

    Hart, Robert Theodore, Jr.

    The structures and optical properties of (K2O)15(Nb 2O5)15(TeO2)70 glass and glass ceramic have been studied in order to understand the second harmonic generation observed from the glass ceramic. We have used 93Nb NMR, Raman spectroscopy, differential scanning calorimetry, small angle x-ray scattering, transmission electron microscopy, and powder x-ray and neutron scattering. We find that there is a microstructure consistent with binodal phase separation leading to spherical inclusions ˜20 nm in size. Upon heat treatment, these domains become nanocrystals of K2Te 4O9. A theory of optical heterogeneity is used to describe the observed second harmonic generation which is ˜95 times more intense that quartz. The chi(2) value for this material is 3.0 x 10-9 esu. A second project has used 125Te and 17O NMR to study alkali tellurite glasses in the system (M2O) x(TeO2)10-x, where M = Li, Na or K and x = 1, 2 or 3. The 125Te results show that complex models of network modification are needed to explain the resulting spectra that include a distribution of polyhedral tellurite units at all compositions. The 17O results show that there is a clear distinction between bridging and non-bridging oxygen sites in tellurite crystals and that sophisticated NMR experiments should be able to distinguish them in the glasses. Further, we have used Extended Huckel theory tight-binding calculations to predict the 17O NMR shifts of SiO2, GeO 2 and TeO2. We find that these calculations allow accurate predictions of the chemical shifts based solely on the trend in valence orbital size, and that expensive calculations of electron currents need not be used for this application.

  20. Properties of Desert Sand and CMAS Glass

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Choi, Sung R.

    2014-01-01

    As-received desert sand from a Middle East country has been characterized for its phase composition and thermal stability. X-ray diffraction analysis showed the presence of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4.2H2O), and NaAlSi3O8 phases in as-received desert sand and showed weight loss of approx. 35 percent due to decomposition of CaCO3 and CaSO4.2H2O when heated to 1400 C. A batch of as-received desert sand was melted into calcium magnesium aluminosilicate (CMAS) glass at approx. 1500 C. From inductively coupled plasma-atomic emission spectrometry, chemical composition of the CMAS glass was analyzed to be 27.8CaO-4MgO-5Al2O3-61.6SiO2-0.6Fe2O3-1K2O (mole percent). Various physical, thermal and mechanical properties of the glass have been evaluated. Bulk density of CMAS glass was 2.69 g/cc, Young's modulus 92 GPa, Shear modulus 36 GPa, Poisson's ratio 0.28, dilatometric glass transition temperature (T (sub g)) 706 C, softening point (T (sub d)) 764 C, Vickers microhardness 6.3 +/- 0.4 GPa, indentation fracture toughness 0.75 +/- 0.15 MPa.m (sup 1/2), and coefficient of thermal expansion (CTE) 9.8 x 10 (exp -6)/degC in the temperature range 25 to 700 C. Temperature dependence of viscosity has also been estimated from various reference points of the CMAS glass using the Vogel-Fulcher-Tamman (VFT) equation. The glass remained amorphous after heat treating at 850 C for 10 hr but crystallized into CaSiO3 and Ca-Mg-Al silicate phases at 900 C or higher temperatures. Crystallization kinetics of the CMAS glass has also been investigated by differential thermal analysis (DTA). Activation energies for the crystallization of two different phases in the glass were calculated to be 403 and 483 kJ/mol, respectively.

  1. Chemical effects of lanthanides and actinides in glasses determined with electron energy loss spectroscopy

    SciTech Connect

    Fortner, J.A.; Buck, E.C.; Ellison, A.J.G.; Bates, J.K.

    1996-07-01

    Chemical and structural environments of f-electron elements in glasses are the origin of many of the important properties of materials with these elements; thus oxidation state and chemical coordination of lanthanides and actinides in host materials is an important design consideration in optically active glasses, magnetic materials, perovskite superconductors, and nuclear waste materials. We have made use of the line shapes of Ce to determine its oxidation state in alkali borosilicate glasses being developed for immobilization of Pu. Examination of several prototype waste glass compositions with EELS shows that the redox state of Ce doped to 7 wt% could be varied by suitable choice of alkali elements. EELS for a Pu-doped glass illustrate the small actinide N{sub 4}/N{sub 5} intensity ratio and show that the Pu-N{sub 4,5} white line cross section is comparable to that of Gd M{sub 4,5}.

  2. Spectroscopic analysis (FTIR, Raman) of water in mafic and intermediate glasses and glass inclusions

    NASA Astrophysics Data System (ADS)

    Mercier, Maxime; Muro, Andrea Di; Métrich, Nicole; Giordano, Daniele; Belhadj, Olfa; Mandeville, Charles W.

    2010-10-01

    Micro-Raman spectroscopy, even though a very promising technique, is not still routinely applied to analyse H 2O in silicate glasses. The accuracy of Raman water determinations critically depends on the capability to predict and take into account both the matrix effects (bulk glass composition) and the analytical conditions on band intensities. On the other hand, micro-Fourier transform infrared spectroscopy is commonly used to measure the hydrous absorbing species (e.g., hydroxyl OH - and molecular H 2O) in natural glasses, but requires critical assumptions for the study of crystal-hosted glasses. Here, we quantify for the first time the matrix effect of Raman external calibration procedures for the quantification of the total H 2O content (H 2O T = OH - + H 2O m) in natural silicate glasses. The procedures are based on the calibration of either the absolute (external calibration) or scaled (parameterisation) intensity of the 3550 cm -1 band. A total of 67 mafic (basanite, basalt) and intermediate (andesite) glasses hosted in olivines, having between 0.2 and 4.8 wt% of H 2O, was analysed. Our new dataset demonstrates, for given water content, the height (intensity) of Raman H 2O T band depends on glass density, reflectance and water environment. Hence this matrix effect must be considered in the quantification of H 2O by Raman spectroscopy irrespective of the procedure, whereas the parameterisation mainly helps to predict and verify the self-consistency of the Raman results. In addition, to validate the capability of the micro-Raman to accurately determine the H 2O content of multicomponent aluminosilicate glasses, a subset of 23 glasses was analysed by both micro-Raman and micro-FTIR spectroscopy using the band at 3550 cm -1. We provide new FTIR absorptivity coefficients ( ɛ3550) for basalt (62.80 ± 0.8 L mol -1 cm -1) and basanite (43.96 ± 0.6 L mol -1 cm -1). These values, together with an exhaustive review of literature data, confirm the non-linear decline

  3. Thermomechanical Fatigue Behavior of a Silicon Carbide Fiber-Reinforced Calcium Aluminosilicate Glass-Ceramic Matrix Composite.

    DTIC Science & Technology

    1992-08-01

    The impact of these factors complicating hysteresis analysis may be reduced if the effects of imperfect thermomechanical cycles on material behavior...Temperature," in Fracture Mechanics of Ceramics. Vol. 7: ComPosites. Impact Statistics and High-Temperature Phenomena, Bradt, R.C., Evans, A.G., Hasselman...r), and hoop (0) directions for conditions of applied thermal and mechanical loads may be computed as Ogm A[1 + (b)21] -t, applied(•) (33) armn A 1

  4. Effect of variable valence impurities on the formation of bismuth-related optical centres in a silicate glass

    SciTech Connect

    Galagan, B I; Denker, B I; Lili Hu; Sverchkov, S E; Shulman, I L; Dianov, Evgenii M

    2012-10-31

    We have studied the effect of variable valence impurities (cerium and iron) on the formation of bismuth-related IR luminescence centres and the optical loss between 1000 and 1300 nm in a magnesium aluminosilicate glass. The results demonstrate that additional doping of the glass with ceria leads to effective bleaching in a wide spectral range, including the luminescence range of the bismuth centres. At the same time, ceria reduces the concentration of luminescence centres. Gamma irradiation of the glass bleached by cerium restores the luminescence centres but leads to a background loss in a wide spectral range. Iron is shown to be a very harmful impurity in bismuth-doped active media: even trace levels of iron prevent the formation of bismuth-related active centres in the glass and produce a strong, broad absorption band centred near 1 {mu}m. (luminescence of glasses)

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

    DOEpatents

    Soung, W.Y.

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

  6. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  7. Alkali-aggregate reaction in concrete containing high-alkali cement and granite aggregate

    SciTech Connect

    Owsiak, Z

    2004-01-01

    The paper discusses results of the research into the influence of high-alkali Portland cement on granite aggregate. The deformation of the concrete structure occurred after 18 months. The research was carried out by means of a scanning electron microscope equipped with a high-energy dispersive X-ray analyzer that allowed observation of unpolished sections of concrete bars exhibiting the cracking pattern typical of the alkali-silica reaction. Both the microscopic observation and the X-ray elemental analysis confirm the presence of alkali-silica gel and secondary ettringite in the cracks.

  8. Nuclear Magnetic Resonance Studies of Aluminosilicate Gels Prepared in High-Alkaline and Salt-Concentrated Solutions

    SciTech Connect

    Wang, Li Q.; Mattigod, Shas V.; Parker, Kent E.; Hobbs, David T.; McCready, David E.

    2005-11-01

    Solid-state 29Si, 27Al, and 23Na MAS (magic angle spinning) NMR techniques in combination with x-ray powder diffraction (XRD) are used to characterize aluminosilicate gels as a function of composition, pH, and reaction times. These gels were prepared at 80 C using initial solutions with low Si/Al ratios, high alkaline and salt concentrations that are characteristic of nuclear tank wastes. XRD data show that cancrinite and sodalite are the main crystalline phases in the aluminosilicate gels produced. It is found that the pH and the salt content have significant effects on the nature of the aluminosilicate gels. Higher pH appears to increase the rate of crystallization, the degree of overall crystallinity and the percentage of cancrinite phases in aluminosilicate gels, whereas the high salt concentration promotes the formation of cancrinite and sodalite and prohibits the formation of other zeolites. Complementary to XRD, NMR is extremely useful for providing the information on the structure of amorphous intermediate gels with no long-range order.

  9. Salts of alkali metal anions and process of preparing same

    DOEpatents

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

    1978-01-01

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

  10. Characterization of enameled glass excavated from Laem Pho, southern Thailand

    NASA Astrophysics Data System (ADS)

    Dhanmanonda, W.; Won-in, K.; Tancharakorn, S.; Tantanuch, W.; Thongleurm, C.; Kamwanna, T.; Dararutana, P.

    2012-07-01

    Laem Pho in Surat Thani, southern province of Thailand is one of the most important historic site on the eastern shore of the Gulf of Thailand. In this work, the enameled glass fragments which looked-like Islamic glass mainly excavated from this site were analyzed using SEM-EDS, PIXE and μ-XRF, in order to understand the chemical composition by comparing the archaeological data and topology. The structure of the enameled decoration was also studied. The resulting data indicated that high-magnesia alkali-lime silicate glass was produced. The presence of transition metals such as copper, iron and manganese were affected on the glass colorations. Typological classifications, technological observations and comparative studies serve to clarify the development and cultural inter-relationships of various glass objects along the trade and exchange networks in ancient maritime.

  11. Mechanical, Thermal and Conduction Characteristics of Binary Phosphate Glasses

    NASA Astrophysics Data System (ADS)

    Dabas, Prashant; Hariharan, K.

    2013-07-01

    Glass forming limit of binary phosphate glasses xLi2O-(100-x)P2O5 is extended from 66 mol% to 72 mol% using a home-built rapid quenching setup. The hardness, hygroscopicity and thermodynamic fragility for the full composition range (30≤x≤72) are quantified using the Vickers hardness test, dissolution rates and the fragility index, respectively. Depending on the alkali content, the glasses behave differently w.r.t. to hardness and hygroscopicity while the thermodynamic fragility decreases progressively with increase in lithium concentration. The conduction characteristics reveal that for ultraphosphate glasses weak electrolyte approach is more suitable to explain the variation of ionic conductivity and activation energy while for polyphosphate glasses strong electrolyte approach is more appropriate.

  12. The utilization of thin film transistor liquid crystal display waste glass as a pozzolanic material.

    PubMed

    Lin, K L; Huang, Wu-Jang; Shie, J L; Lee, T C; Wang, K S; Lee, C H

    2009-04-30

    This investigation elucidates the pozzolanic behavior of waste glass blended cement (WGBC) paste used in thin film transistor liquid crystal displays (TFT-LCD). X-ray diffraction (XRD) results demonstrate that the TFT-LCD waste glass was entirely non-crystalline. The leaching concentrations of the clay and TFT-LCD waste glass all met the current regulatory thresholds of the Taiwan EPA. The pozzolanic strength activity indices of TFT-LCD waste glass at 28 days and 56 days were 89% and 92%, respectively. Accordingly, this material can be regarded as a good pozzolanic material. The amount of TFT-LCD waste glass that is mixed into WGBC pastes affects the strength of the pastes. The strength of the paste clearly declined as the amount of TFT-LCD waste glass increased. XRD patterns indicated that the major difference was the presence of hydrates of calcium silicate (CSH, 2 theta=32.1 degrees), aluminate and aluminosilicate, which was present in WGBC pastes. Portland cement may have increased the alkalinity of the solution and induced the decomposition of the glass phase network. WGBC pastes that contained 40% TFT-LCD waste glass have markedly lower gel/space ratios and exhibit less degree of hydration than ordinary Portland cement (OPC) pastes. The most satisfactory characteristics of the strength were observed when the mixing ratio of the TFT-LCD waste glass was 10%.

  13. Crack-resistant Al2O3–SiO2 glasses

    NASA Astrophysics Data System (ADS)

    Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki

    2016-04-01

    Obtaining “hard” and “crack-resistant” glasses have always been of great important in glass science and glass technology. However, in most commercial glasses both properties are not compatible. In this work, colorless and transparent xAl2O3–(100–x)SiO2 glasses (30 ≤ x ≤ 60) were fabricated by the aerodynamic levitation technique. The elastic moduli and Vickers hardness monotonically increased with an increase in the atomic packing density as the Al2O3 content increased. Although a higher atomic packing density generally enhances crack formation in conventional oxide glasses, the indentation cracking resistance increased by approximately seven times with an increase in atomic packing density in binary Al2O3–SiO2 glasses. In particular, the composition of 60Al2O3•40SiO2 glass, which is identical to that of mullite, has extraordinary high cracking resistance with high elastic moduli and Vickers hardness. The results indicate that there exist aluminosilicate compositions that can produce hard and damage-tolerant glasses.

  14. Crack-resistant Al2O3–SiO2 glasses

    PubMed Central

    Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki

    2016-01-01

    Obtaining “hard” and “crack-resistant” glasses have always been of great important in glass science and glass technology. However, in most commercial glasses both properties are not compatible. In this work, colorless and transparent xAl2O3–(100–x)SiO2 glasses (30 ≤ x ≤ 60) were fabricated by the aerodynamic levitation technique. The elastic moduli and Vickers hardness monotonically increased with an increase in the atomic packing density as the Al2O3 content increased. Although a higher atomic packing density generally enhances crack formation in conventional oxide glasses, the indentation cracking resistance increased by approximately seven times with an increase in atomic packing density in binary Al2O3–SiO2 glasses. In particular, the composition of 60Al2O3•40SiO2 glass, which is identical to that of mullite, has extraordinary high cracking resistance with high elastic moduli and Vickers hardness. The results indicate that there exist aluminosilicate compositions that can produce hard and damage-tolerant glasses. PMID:27053006

  15. Ultrapure glass optical waveguide development in microgravity by the sol-gel process

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.

    1980-01-01

    The alkali-borosilicate system was selected as the glass system for the preparation of ultrapure low loss glasses suitable for optical communication. The effect of different oxide contents on the absorption loss was critically reviewed. One composition was chosen to develop the gel preparation procedure in the alkali-borosilicate system. In addition, several procedures for the preparation of gels based on two different approaches were developed. The influence of different preparation parameters were investigated qualitatively. Several conclusions are drawn from the results.

  16. Preparation and characterization of cesium-137 aluminosilicate pellets for radioactive source applications

    SciTech Connect

    Schultz, F.J.; Tompkins, J.A.; Haff, K.W.; Case, F.N.

    1981-07-01

    Twenty-seven fully loaded /sup 137/Cs aluminosilicate pellets were fabricated in a hot cell by the vacuum hot pressing of a cesium carbonate/montmorillonite clay mixture at 1500/sup 0/C and 570 psig. Four pellets were selected for characterization studies which included calorimetric measurements, metallography, scanning electron microscope and electron backscattering (SEM-BSE), electron microprobe, x-ray diffraction, and cesium ion leachability measurements. Each test pellet contained 437 to 450 curies of /sup 137/Cs as determined by calorimetric measurements. Metallographic examinations revealed a two-phase system: a primary, granular, gray matrix phase containing large and small pores and small pore agglomerations, and a secondary fused phase interspersed throughout the gray matrix. SEM-BSE analyses showed that cesium and silicon were uniformly distributed throughout both phases of the pellet. This indicated that the cesium-silicon-clay reaction went to completion. Aluminum homogeneity was unconfirmed due to the high background noise associated with the inherent radioactivity of the test specimens. X-ray diffraction analyses of both radioactive and non-radioactive aluminosilicate pellets confirmed the crystal lattice structure to be pollucite. Cesium ion quasistatic leachability measurements determined the leach rates of fully loaded /sup 137/Cs sectioned pollucite pellets to date to be 4.61 to 34.4 x 10/sup -10/ kg m/sup -2/s/sup -1/, while static leach tests performed on unsectioned fully loaded pellets showed the leach rates of the cesium ion to date to be 2.25 to 3.41 x 10/sup -12/ kg m/sup -2/s/sup -1/. The cesium ion diffusion coefficients through the pollucite pellet were calculated using Fick's first and second laws of diffusion. The diffusion coefficients calculated for three tracer level /sup 137/Cs aluminosilicate pellets were 1.29 x 10/sup -16/m/sup 2/s/sup -1/, 6.88 x 10/sup -17/m/sup 2/s/sup -1/, and 1.35 x 10/sup -17/m/sup 2/s/sup -1/, respectively.

  17. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  18. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  19. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  20. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  1. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  2. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  3. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  4. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  5. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  6. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  7. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  8. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  10. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  12. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  13. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  14. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  15. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  16. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  17. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  19. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  20. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  1. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  2. Comprehensive Chemical Characterisation of Byzantine Glass Weights

    PubMed Central

    Schibille, Nadine; Meek, Andrew; Tobias, Bendeguz; Entwistle, Chris; Avisseau-Broustet, Mathilde; Da Mota, Henrique; Gratuze, Bernard

    2016-01-01

    The understanding of the glass trade in the first millennium CE relies on the characterisation of well-dated compositional groups and the identification of their primary production sites. 275 Byzantine glass weights from the British Museum and the Bibliothèque nationale de France dating to the sixth and seventh century were analysed by LA-ICP-MS. Multivariate statistical and graphical data analysis discriminated between six main primary glass types. Primary glass sources were differentiated based on multi-dimensional comparison of silica-derived elements (MgO, Al2O3, CaO, TiO2, Fe2O3, ZrO2) and components associated with the alkali source (Li2O, B2O3). Along with Egyptian and Levantine origins of the glassmaking sands, variations in the natron source possibly point to the exploitation of two different natron deposits. Differences in strontium to calcium ratios revealed variations in the carbonate fractions in the sand. At least two cobalt sources were employed as colouring agents, one of which shows strong correlations with nickel, indicating a specific post-Roman cobalt source. Typological evidence identified chronological developments in the use of the different glass groups. Throughout the sixth century, Byzantine glass weights were predominately produced from two glasses that are probably of an Egyptian origin (Foy-2 and Foy-2 high Fe). Towards the second half of the sixth century a new but related plant-ash glass type emerged (Magby). Levantine I was likewise found among the late sixth- to early seventh-century samples. The use of different dies for the same batch testifies to large-scale, centralised production of the weights, while the same die used for different primary production groups demonstrates the co-existence of alternative sources of supply. Given the comprehensive design of our study, these results can be extrapolated to the wider early Byzantine glass industry and its changes at large. PMID:27959963

  3. Comprehensive Chemical Characterisation of Byzantine Glass Weights.

    PubMed

    Schibille, Nadine; Meek, Andrew; Tobias, Bendeguz; Entwistle, Chris; Avisseau-Broustet, Mathilde; Da Mota, Henrique; Gratuze, Bernard

    2016-01-01

    The understanding of the glass trade in the first millennium CE relies on the characterisation of well-dated compositional groups and the identification of their primary production sites. 275 Byzantine glass weights from the British Museum and the Bibliothèque nationale de France dating to the sixth and seventh century were analysed by LA-ICP-MS. Multivariate statistical and graphical data analysis discriminated between six main primary glass types. Primary glass sources were differentiated based on multi-dimensional comparison of silica-derived elements (MgO, Al2O3, CaO, TiO2, Fe2O3, ZrO2) and components associated with the alkali source (Li2O, B2O3). Along with Egyptian and Levantine origins of the glassmaking sands, variations in the natron source possibly point to the exploitation of two different natron deposits. Differences in strontium to calcium ratios revealed variations in the carbonate fractions in the sand. At least two cobalt sources were employed as colouring agents, one of which shows strong correlations with nickel, indicating a specific post-Roman cobalt source. Typological evidence identified chronological developments in the use of the different glass groups. Throughout the sixth century, Byzantine glass weights were predominately produced from two glasses that are probably of an Egyptian origin (Foy-2 and Foy-2 high Fe). Towards the second half of the sixth century a new but related plant-ash glass type emerged (Magby). Levantine I was likewise found among the late sixth- to early seventh-century samples. The use of different dies for the same batch testifies to large-scale, centralised production of the weights, while the same die used for different primary production groups demonstrates the co-existence of alternative sources of supply. Given the comprehensive design of our study, these results can be extrapolated to the wider early Byzantine glass industry and its changes at large.

  4. Chromium liquid waste inertization in an inorganic alkali activated matrix: leaching and NMR multinuclear approach.

    PubMed

    Ponzoni, Chiara; Lancellotti, Isabella; Barbieri, Luisa; Spinella, Alberto; Saladino, Maria Luisa; Martino, Delia Chillura; Caponetti, Eugenio; Armetta, Francesco; Leonelli, Cristina

    2015-04-09

    A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process--from the precursor dissolution to the final geopolymer matrix hardening--of different geopolymers containing a waste amount ranging from 3 to 20%wt and their capability to inertize chromium cations were studied by: i) the leaching tests, according to the EN 12,457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the aluminosilicate matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of TOT bonds (where T is Al or Si) by (29)Si and (27)Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for geopolymers containing high amounts of waste (10-20%wt). The results show the formation of a stable matrix after only 15 days independently on the waste amount introduced; the longer curing times increase the matrices stabilities and their ability to immobilize chromium cations. The maximum amount of waste that can be inertized is around 10 wt% after a curing time of 28 days.

  5. Technical improvements in 19th century Belgian window glass production

    NASA Astrophysics Data System (ADS)

    Lauriks, Leen; Collette, Quentin; Wouters, Ine; Belis, Jan

    Glass was used since the Roman age in the building envelope, but it became widely applied together with iron since the 19th century. Belgium was a major producer of window glass during the nineteenth century and the majority of the produced window glass was exported all over the world. Investigating the literature on the development of 19th century Belgian window glass production is therefore internationally relevant. In the 17th century, wood was replaced as a fuel by coal. In the 19th century, the regenerative tank furnace applied gas as a fuel in a continuous glass production process. The advantages were a clean production, a more constant and higher temperature in the furnace and a fuel saving. The French chemist Nicolas Leblanc (1787-1793) and later the Belgian chemist Ernest Solvay (1863) invented processes to produce alkali out of common salt. The artificial soda ash improved the quality and aesthetics of the glass plates. During the 19th century, the glass production was industrialized, influencing the operation of furnaces, the improvement of raw materials as well as the applied energy sources. Although the production process was industrialized, glassblowing was still the work of an individual. By improving his work tools, he was able to create larger glass plates. The developments in the annealing process followed this evolution. The industry had to wait until the invention of the drawn glass in the beginning of the 20th century to fully industrialise the window glass manufacture process.

  6. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    DOEpatents

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  7. Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

    SciTech Connect

    Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

    2016-03-25

    The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that are currently of the most commercial interest.

  8. Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

    DOE PAGES

    Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

    2016-03-25

    The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that aremore » currently of the most commercial interest.« less

  9. Constraining 17O and 27Al NMR spectra of high-pressure crystals and glasses: New data for jadeite, pyrope, grossular, and mullite

    USGS Publications Warehouse

    Kelsey, K.E.; Stebbins, J.F.; Du, L.-S.; Hankins, B.

    2007-01-01

    The 17O NMR spectra of glasses quenched from melts at high pressure are often difficult to interpret due to overlapping peaks and lack of crystalline model compounds. High-pressure aluminosilicate glasses often contain significant amounts of [5]Al and [6]Al, thus these high-pressure glasses must contain oxygen bonded to high-coordinated aluminum. The 17O NMR parameters for the minerals jadeite, pyrope, grossular, and mullite are presented to assist interpretation of glass spectra and to help test quantum chemical calculations. The 17O NMR parameters for jadeite and grossular support previous peak assignments of oxygen bonded to Si and high-coordinated Al in high-pressure glasses as well as quantum chemical calculations. The oxygen tricluster in mullite is very similar to the previously observed tricluster in grossite (CaAl4 O7) and suspected triclusters in glasses. We also present 27Al NMR spectra for pyrope, grossular, and mullite.

  10. Ingestion of caustic alkali farm products.

    PubMed

    Neidich, G

    1993-01-01

    Since the Poison Prevention Packaging Act took effect, the number of ingestions of caustic alkali from household products has been significantly reduced. Commercial caustic alkalis used on farms, however, were not included in this legislation. Fourteen children over a 5 year period were seen after ingestion of commercial caustic alkalis used on farms. Seven of the children had ingested liquid pipeline cleaners and seven had ingested solid agents used for a variety of reasons. Six of seven children ingesting liquid agents did so from nonoriginal containers into which the caustic had been transferred for convenience. All seven children ingesting solid agents did so from the original container. Eight of the 14 children were found to have second-degree or worse esophageal involvement. Both solid and liquid caustic agents used commercially on farms can cause significant morbidity. Development of a child-resistant container for daily transfer of liquid pipeline agents could be helpful in preventing injuries from liquid pipeline cleaners. Pediatric gastroenterologists as well as primary care physicians in rural areas should be familiar with this type of injury and should take an active role in instructing parents of children living on farms to prevent such injuries. Extension of the Poison Prevention Packaging Act to caustic alkalis used on farms needs to be considered.

  11. The Additive Coloration of Alkali Halides

    ERIC Educational Resources Information Center

    Jirgal, G. H.; and others

    1969-01-01

    Describes the construction and use of an inexpensive, vacuum furnace designed to produce F-centers in alkali halide crystals by additive coloration. The method described avoids corrosion or contamination during the coloration process. Examination of the resultant crystals is discussed and several experiments using additively colored crystals are…

  12. Cohesive Energy of the Alkali Metals.

    ERIC Educational Resources Information Center

    Poole, R. T.

    1980-01-01

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

  13. Terahertz radiation in alkali vapor plasmas

    SciTech Connect

    Sun, Xuan; Zhang, X.-C.

    2014-05-12

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

  14. Composites of Polyindole nanowires within Silicate and Aluminosilicate hosts with distinct conductive properties

    NASA Astrophysics Data System (ADS)

    Juárez, J. M.; Gómez Costa, M. B.; Anunziata, O. A.

    2016-07-01

    Nanostructured silicate SBA-15 and aluminosilicate AlSBA-15 were synthesized in order to prepare polyindole composites. The Silica mesoporous materials were prepared by sol- gel method and alumination using post-synthesis technique and analysed by different methods (XRD, BET, TEM, and FTIR). Polyindole/host composites were prepared by in situ oxidative polymerization of pre-adsorbed indole, employing Cl3Fe as oxidant. TG, FTIR, BET, XRD, SEM and TEM were used to characterize the resulting composites. These studies show that the porous structures of the materials are preserved after polymerization, and polyindole is found within the porous channels. The composites have an electrical conductivity range between values higher than those of the pure chemically synthesized polyindole, close to those of the pure electrochemically synthesized polymer and lower than those of the pure chemically synthesized polymer, in the order of 10-8 S/cm.

  15. Tailoring of Boehmite-Derived Aluminosilicate Aerogel Structure and Properties: Influence of Ti Addition

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Guo, Haiquan; Sheets, Erik J.; Miller, Derek R.; Newlin, Katy N.

    2010-01-01

    Aluminosilicate aerogels offer potential for extremely low thermal conductivities at temperatures greater than 900 C, beyond where silica aerogels reach their upper temperature limits. Aerogels have been synthesized at various Al:Si ratios, including mullite compositions, using Boehmite (AlOOH) as the Al source, and tetraethoxy orthosilicate as the Si precursor. The Boehmite-derived aerogels are found to form by a self-assembly process of AlOOH crystallites, with Si-O groups on the surface of an alumina skeleton. Morphology, surface area and pore size varies with the crystallite size of the starting Boehmite powder, as well as with synthesis parameters. Ternary systems, including Al-Si-Ti aerogels incorporating a soluble Ti precursor, are possible with careful control of pH. The addition of Ti influences sol viscosity, gelation time pore structure and pore size distribution, as well as phase formation on heat treatment.

  16. Structural and dynamic properties of calcium aluminosilicate melts: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Bouhadja, M.; Jakse, N.; Pasturel, A.

    2013-06-01

    The structural and dynamic properties of calcium aluminosilicate (CaO-Al2O3)1-x(SiO2)x melts with low silica content, namely, along the concentration ratio R = 1 are studied by classical molecular dynamics. An empirical potential has been developed here on the basis of our previous ab initio molecular dynamics. The new potential gives a description of the structural as well as the dynamics with a good accuracy. The self-intermediate scattering function and associated α-relaxation times are analyzed within the mode-coupling theory. Our results indicate a decrease of the fragility whose structural origin is a reduction of the number of fivefold coordinated Al atoms and non-bridging oxygen.

  17. A facile strategy to recycle template P123 from mesoporous aluminosilicates by ultrasonic extraction.

    PubMed

    Jin, Jun-su; Cao, Li; Su, Guang-xun; Xu, Chun-yan; Zhang, Ze-ting; Gao, Xiong-hou; Liu, Hong-hai; Liu, Hong-tao

    2014-09-01

    High synthesis cost of mesoporous aluminosilicates (MA) limits their practical application. Recycling of copolymer template employed in preparation of MA is an effective way to reduce the synthesis cost. An ultrasonic extraction strategy for recycling of organic template P123 in MAs is reported. Effects of different extraction parameters on P123 recovery are investigated and the optimum conditions are obtained. 75.0% P123 is recovered from MAs within 10 min by one-step ultrasonication. Characterizations indicated that the resulting P123-free MA (MA-U) exhibits excellent properties compared with that of calcined products. Moreover, recovered P123 can be employed to synthesize high hydrothermally stable MA. This investigation provides a facile strategy to recycle P123 from MA.

  18. Impact of ZnO on the structure of aluminosilicate glazes

    NASA Astrophysics Data System (ADS)

    Leśniak, M.; Partyka, J.; Sitarz, M.

    2016-12-01

    This paper focuses on the effect of the ZnO content on the microstructure and structure of the internal aluminosilicooxygen network of the glazes from the SiO2-Al2O3-Na2O-K2O-CaO system. In order to examine the real composition of the obtained samples, a chemical analysis was performed. In order to determine the microstructure, research using the scanning electron microscope (SEM) with EDS was done. For the inner structural study, X-ray diffraction (XRD), Raman spectroscopy as well as MIR, FIR spectroscopy and 29Si, 27Al MAS NMR were performed. The study has shown that the experimental glazes are amorphous material. The studies showed that, zinc ions in the structure of the aluminosilicate glazes cause depolymerization of silicon-oxygen network. This means that, the zinc ions Zn2+ in the tested glazes are in octahedral coordination.

  19. Effect of additions of aluminosilicate and silicate materials on the softening temperature of chromite ore

    NASA Astrophysics Data System (ADS)

    Zhdanov, A. V.; Nurmaganbetova, B. N.; Pavlov, V. A.

    2015-07-01

    The temperatures of the beginning and end of softening and the temperature range of softening of the fines of the rich chromite ore of the Donskoy Ore Mining & Processing Plant in Kazakhstan are experimentally determined. The following natural and technical silica-containing materials, which are considered as fluxing additions to decrease the melting temperature of the chromite ore, are investigated: aluminosilicate clays, microsilica, and quartzite of various fractions. The effect of additions of the natural and technical silica-containing materials on the temperatures of the beginning and end of softening and the temperature range of softening of the chromite ore of DODPE is analyzed. The influences of various materials and their fraction compositions on the temperature of softening of the chromite ores are compared.

  20. Investigating the Potential of Single-Walled Aluminosilicate Nanotubes in Water Desalination.

    PubMed

    Liou, Kai-Hsin; Kang, Dun-Yen; Lin, Li-Chiang

    2017-01-18

    Water shortage has become a critical issue. To facilitate the large-scale deployment of reverse-osmosis water desalination to produce fresh water, discovering novel membranes is essential. Here, we computationally demonstrate the great potential of single-walled aluminosilicate nanotubes (AlSiNTs), materials that can be synthesized through scalable methods, in desalination. State-of-the-art molecular dynamics simulations were employed to investigate the desalination performance and structure-performance relationship of AlSiNTs. Free energy profiles, passage time distribution, and water density map were also analyzed to further understand the dependence of transport properties on diameter and water dynamics in the nanotubes. AlSiNTs with an inner diameter of 0.86 nm were found to fully reject NaCl ions while allowing orders of magnitude higher water fluxes compared to currently available reverse osmosis membranes, providing opportunities in water desalination.

  1. Alkali activation processes for incinerator residues management.

    PubMed

    Lancellotti, Isabella; Ponzoni, Chiara; Barbieri, Luisa; Leonelli, Cristina

    2013-08-01

    Incinerator bottom ash (BA) is produced in large amount worldwide and in Italy, where 5.1 millionstons of municipal solid residues have been incinerated in 2010, corresponding to 1.2-1.5 millionstons of produced bottom ash. This residue has been used in the present study for producing dense geopolymers containing high percentage (50-70 wt%) of ash. The amount of potentially reactive aluminosilicate fraction in the ash has been determined by means of test in NaOH. The final properties of geopolymers prepared with or without taking into account this reactive fraction have been compared. The results showed that due to the presence of both amorphous and crystalline fractions with a different degree of reactivity, the incinerator BA geopolymers exhibit significant differences in terms of Si/Al ratio and microstructure when reactive fraction is considered.

  2. Pinhole Glasses

    ERIC Educational Resources Information Center

    Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

    2008-01-01

    Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole…

  3. Raman Spectroscopic Studies of the High Pressure Behavior of Network Forming Tetrahedral Oxide Glasses.

    NASA Astrophysics Data System (ADS)

    Durben, Daniel John

    The ambient temperature structural and vibrational properties of a series of network forming tetrahedral oxide glasses have been investigated as a function of pressure with Raman spectroscopy. Glass samples were chosen to examine a range of network structures, from the fully polymerized GeO_2, to the partially depolymerized alkali tetrasilicates and disilicates, to the fully depolymerized forsterite. The Raman data suggest that fully polymerized oxide glass structures undergo network cation coordination changes in response to extreme compression through the involvement of bridging oxygens, without requiring bond breaking reactions. Spectral changes observed in partially depolymerized network glass structures are consistent with an increase in Si coordination during compression at the expense of nonbridging oxygens. The pressure range over which the coordination change occurs appears to be controlled by the size and concentration of alkali cations in the structure and depends on a balance between the competing beta-state conversion mechanism at low alkali content and steric considerations at higher alkali content. High pressure structural changes are largely reversible upon decompression, albeit with a large hysteresis. However, the spectra suggest that the breakup of the high coordinated network during the backtransformation to tetrahedral Si coordination occurs without a memory of the original Q -speciation or Si-O ring distribution. Thus, the backtransformation to low coordinated species upon decompression, occurring while the glass is compacted, favors a redistribution of Q-species and ring statistics relative to the original ambient structure.

  4. The geochemistry and provenance of Apollo 16 mafic glasses

    NASA Astrophysics Data System (ADS)

    Zeigler, Ryan A.; Korotev, Randy L.; Jolliff, Bradley L.; Haskin, Larry A.; Floss, Christine

    2006-12-01

    , alkali-rich, and moderately titaniferous; they are unlike any previously recognized lunar lithology or glass group. Their likely provenance is within the Procellarum KREEP Terrane, but they are not found within the Apollo 16 ancient regolith breccias and therefore were likely deposited at the Apollo 16 site post-Imbrium. The basaltic-andesite glasses are the most ferroan variety of KREEP yet discovered.

  5. Imprinting the surface of mesoporous aluminosilicates using organic structure-directing agents

    NASA Astrophysics Data System (ADS)

    Sawant, Kaveri R.

    Combining the positive structural features of mesoporous materials and microporous zeolite aluminosilicates can lead to the synthesis and application of new materials useful for catalytic processes involving large organic reactant molecules. We used organic structure-directing agents (SDAs), typically used for the synthesis of zeolites, to imprint the surface of existing mesoporous materials to create novel materials with enhanced structural properties towards this aim: materials with large well-ordered pores allowing access to large reactants with strong accessible acid sites on the surface of the pores leading to stable and active catalysts. We developed new protocols for incorporating tetrapropyl ammonium and N,N,N-trimethyl-1-adamantylammonium, SDAs used for the synthesis of the zeolites ZSM-5 (MFI) and MCM-22 (MWW) respectively, into the walls of the siliceous mesoporous material SBA-15 by using a combination of an organic solvent (glycerol) and water, to form novel porous materials. We studied the evolution of the modified pore structure of the materials by a battery of characterization techniques. Results indicate that the new materials have well-ordered pores with significantly larger mesopore diameters and structurally modified thinner, denser pore walls. We carried out similar treatments and characterization on the aluminum containing form of SBA-15, Al-SBA-15, with high and low amounts of aluminum. Pair distribution function analysis was used to analyze the structural differences in the materials and catalytic test reactions such as cumene and n-hexane cracking to detect the presence of strong acid sites like the ones in ZSM-5. Results similar to the treatments on the all-silica materials, although promising, led to novel meso-micro aluminosilicate materials with limited increase in or no catalytic activity with reference to the test reactions employed. This led to the conclusion that the aluminum in the materials was merely a spectator and did not

  6. Calcium-Alkali Syndrome in the Modern Era

    PubMed Central

    Patel, Ami M.; Adeseun, Gbemisola A.; Goldfarb, Stanley

    2013-01-01

    The ingestion of calcium, along with alkali, results in a well-described triad of hypercalcemia, metabolic alkalosis, and renal insufficiency. Over time, the epidemiology and root cause of the syndrome have shifted, such that the disorder, originally called the milk-alkali syndrome, is now better described as the calcium-alkali syndrome. The calcium-alkali syndrome is an important cause of morbidity that may be on the rise, an unintended consequence of shifts in calcium and vitamin D intake in segments of the population. We review the pathophysiology of the calcium-alkali syndrome. PMID:24288027

  7. Short and medium range order in two-component silica glasses by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Inoue, K.; Kataoka, H.; Nagai, Y.; Hasegawa, M.; Kobayashi, Y.

    2014-05-01

    The dependence of chemical composition on the average sizes of subnanometer-scale intrinsic structural open spaces surrounded by glass random networks in two-component silica-based glasses was investigated systematically using positronium (Ps) confined in the open spaces. The average sizes of the open spaces for SiO2-B2O3 and SiO2-GeO2 glasses are only slightly dependent on the chemical compositions because the B2O3 and GeO2 are glass network formers that are incorporated into the glass network of the base SiO2. However, the open space sizes for all SiO2-R2O (R = Li, Na, K) glasses, where R2O is a glass network modifier that occupies the open spaces, decrease rapidly with an increase in the R2O concentration. Despite the large difference in the ionic radii of the alkali metal (R) atoms, the open space sizes decrease similarly for all the alkali metal atoms studied. This dependence of the chemical composition on the open space sizes in SiO2-R2O observed by Ps shows that the alkali metal atoms do not randomly occupy the structural open spaces, but filling of the open spaces by R2O proceeds selectively from the larger to the smaller open spaces as the R2O concentrations are increased.

  8. Ion-implantation-induced stress in glasses: Variation of damage mode efficiency with changes in glass structure

    NASA Astrophysics Data System (ADS)

    Arnold, G. W.

    1988-05-01

    Ion implantation induces lateral stress in glass due to the volume dilatation in the implanted near-surface region. Cantilever-beam experiments allow these quantities to be measured as a function of fluence. For fused silica the stress data for various incident ions are found to scale with atomic collision energy deposition. In sharp contrast, Pyrex (alkali-borosilicate) glass, (1 - x)(Na, K) 2O· xB 2O 3·3SiO 2 glass, and a sodalime (microscope slide) glass, yield stress values which scale with energy deposition into electronic processes. More significantly, this mode of damage production is dominant for the nuclear waste glasses PNL 76-68 and SRP. The void space in fused silica allows room for displaced Si and/or O. For the complex alkali-containing silicates, the interstitial volume is restricted. In the latter case, the probability increases that permanent defects can be formed by ionization-induced bond-breaking and network relaxation. These data imply that alpha-particle ionization energy deposition may be an important factor in nuclear waste glass radiation damage production, but the magnitude of this contribution has not yet been evaluated.

  9. Alkali metal recovery from carbonaceous material conversion process

    DOEpatents

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

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced in the gasifier or similar reaction zone, alkali metal constitutents are recovered from the particles by withdrawing and passing the particles from the reaction zone to an alkali metal recovery zone in the substantial absence of molecular oxygen and treating the particles in the recovery zone with water or an aqueous solution in the substantial absence of molecular oxygen. The solution formed by treating the particles in the recovery zone will contain water-soluble alkali metal constituents and is recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preventing contact of the particles with oxygen as they are withdrawn from the reaction zone and during treatment in the recovery zone avoids the formation of undesirable alkali metal constituents in the aqueous solution produced in the recovery zone and insures maximum recovery of water-soluble alkali metal constituents from the alkali metal residues.

  10. The behaviour of alkali metals in biomass conversion systems

    SciTech Connect

    Hald, P.

    1995-12-31

    Alkali metals present in biomass contribute to problems as agglomeration, deposition and corrosion. In order to reduce the problems. It is of interest to describe the behavior of alkali metals in the conversion systems. Useful tools for die description are equilibrium calculations combined with measurements of gaseous alkali metal and analyses of solid materials. A comprehensive equilibrium study has been conducted and the results organized in tables, showing which alkali metal components can be present, dependent on the temperature and the ratios alkali metal to sulphur and alkali metal to chlorine. The tables presented can be used as a catalogue, giving easy access to equilibrium results. A sampling method for die measurement of gaseous alkali metal is described and the sampling efficiency is given. The developed tools are demonstrated for a straw gasifier and a fluidized bed combustor using a coal/straw mixture as a fuel.

  11. Subtask 6.6 - SiAION Coatings for Alkali-Resistant Silicon Nitride. Topical report

    SciTech Connect

    1997-02-25

    The efficiency of a gas turbine can be improved by increasing operating temperature. Construction materials should both meet high strength requirements and exhibit hot alkali corrosion resistance. Structural ceramics based on silicon nitride are promising candidates for high temperature engineering applications because of their high strength and good resistance to corrosion. Their performance varies significantly with the mechanical properties of boundary phases which, in turn, depend on their chemical composition, thickness of the amorphous phase, and the deformation process. To make silicon nitride ceramics tough, SiAlON ceramics were developed with controlled crystallization of the amorphous grain boundary phase. Crystallization of the grain boundary glass improves the high temperature mechanical properties of silicon nitride ceramics. Thus, the knowledge of silicon oxynitride ceramics corrosion behavior in Na{sub 2}SO{sub 4} becomes important for engineers in designing appropriate part for turbines working at high temperatures. So far there has been no report concerning alkali attack on SiAlON ceramics in the presence of SO{sub 2} and chlorine in flue gas. The goal of this project was to investigate alkali corrosion of SiAlON-Y structural ceramics under combustion conditions in the presence of sodium derived components.

  12. Elemental and isotopic ( 29Si and 18O) tracing of glass alteration mechanisms

    NASA Astrophysics Data System (ADS)

    Valle, Nathalie; Verney-Carron, Aurélie; Sterpenich, Jérôme; Libourel, Guy; Deloule, Etienne; Jollivet, Patrick

    2010-06-01

    To better understand glass alteration mechanisms, especially alteration layers formation, leaching experiments of a borosilicate glass (SON68) doped with a different rare earth element (La, Ce, or Nd) with solutions rich in 29Si and 18O were carried out. The coupled analyses of glass, alteration products, and solution led to a complete elemental and isotopic ( 29Si and 18O) budget. They revealed different behaviours of elements that depend not only on their structural role in the glass, but also on their affinity for alteration products (gel, phyllosilicates, phosphates). However, analyses of both glass and solution are not sufficient to describe the real exchanges occurring between glass and solution. The use of 29Si and 18O tracers gives new insights on the formation of alteration layers. During alteration the phyllosilicates records the isotopic variations of the leaching solution. Their isotopic signatures highlight a mechanism of dissolution/precipitation, which implies equilibrium between the secondary phases and the solution. On the other hand the gel isotopic signature, that is intermediate between the glass and the solution, substantiates the hypothesis that the gel is formed by hydrolysis/condensation reactions. This mechanism can thus explain the influence of the gel formation conditions (alteration conditions, solution saturation) on the structure (reorganisation) and texture (porosity) of this layer and on its protective effect. These hydrolysis/condensation reactions are also certainly involved in the aluminosilicate glass alteration and in the formation of palagonite.

  13. Effect of alkali lignins with different molecular weights from alkali pretreated rice straw hydrolyzate on enzymatic hydrolysis.

    PubMed

    Li, Yun; Qi, Benkun; Luo, Jianquan; Wan, Yinhua

    2016-01-01

    This study investigated the effect of alkali lignins with different molecular weights on enzymatic hydrolysis of lignocellulose. Different alkali lignins fractions, which were obtained from cascade ultrafiltration, were added into the dilute acid pretreated (DAP) and alkali pretreated (AP) rice straws respectively during enzymatic hydrolysis. The results showed that the addition of alkali lignins enhanced the hydrolysis and the enhancement for hydrolysis increased with increasing molecular weights of alkali lignins, with maximum enhancement being 28.69% for DAP and 20.05% for AP, respectively. The enhancement was partly attributed to the improved cellulase activity, and filter paper activity increased by 18.03% when adding lignin with highest molecular weight. It was found that the enhancement of enzymatic hydrolysis was correlated with the adsorption affinity of cellulase on alkali lignins, and the difference in surface charge and hydrophobicity of alkali lignins were responsible for the difference in affinity between cellulase and lignins.

  14. Electrochromic Glasses.

    DTIC Science & Technology

    1980-07-31

    Li20-B203 and Na20-B203 or Te02 . These glasses exhibit for the first time, electrochromic and photochromic behaviour and have potential for use in...the complete spectral distribution of the absorption at levels of 10- cm- I for the first time. In the past, it was only possible to measure low...distribution of the absorption at levels at 10 -cm it was possible, for the first time, to identify extrinsic impurities in highly transparent solids. This

  15. Powder XRD, SEM, and Multinuclear MAS-NMR Investigations of the Interactions Between Glass and Crystalline Phases of Li, Na, or K Ceramic Waste Forms

    SciTech Connect

    Lambregts, Marsha J.; Frank, Steve M.

    2005-08-01

    Interactions between the glass and crystalline phases of ceramic waste forms were investigated via powder X-ray diffraction, scanning electron microscopy, and Si-29, Al-27, Na-23, Li-7, and Cl-35 magic angle spinning nuclear magnetic resonance spectroscopy. LiCl, NaCl, or KCl waste form samples were made with or without glass. The waste forms containing glass consist of sodalite and glass phases with minor amounts of nepheline. Samples without glass form varying amounts of sodalite and nepheline. The glass frit, intended to bind the zeolite particles together, changes in composition, showing marked increases in aluminum and alkali content.

  16. Kramers-Kronig relations in modulation polarimetry diagnostics of glass-ceramics

    NASA Astrophysics Data System (ADS)

    Dudar, B. V.; Matyash, I. E.; Minailova, I. A.; Mishchuk, O. N.; Serdega, B. K.

    2016-10-01

    It has been found that, in an aluminosilicate glass-ceramic sample cut from a massive ingot, there is a correlation of the residual stress with the temperature gradient. The magnitude and coordinate dependence of the stress along the temperature gradient have been determined from the stress-induced linear birefringence measured by the modulation polarimetry technique. Its functional relationship has been established in the form of the Poisson equation with the heterogeneity of the composition due to the preparation conditions. It has been shown that, in the absence of a temperature gradient, the birefringence and dichroism related by the Kramers-Kronig relation play the role of thermodynamic variables.

  17. Hollow microspheres of silica glass and method of manufacture

    DOEpatents

    Downs, Raymond L.; Miller, Wayne J.

    1982-01-01

    A method of manufacturing gel powder suitable for use as a starting material in the manufacture of hollow glass microspheres having a high concentration of silica. The powder is manufactured from a gel containing boron in the amount of about 1% to 20% (oxide equivalent mole percent), alkali metals, specifically potassium and sodium, in an amount exceeding 8% total, and the remainder silicon. Preferably, the ratio of potassium to sodium is greater than 1.5.

  18. Preventing photodarkening in ytterbium-doped high power fiber lasers; correlation to the UV-transparency of the core glass.

    PubMed

    Engholm, M; Norin, L

    2008-01-21

    Photodarkening experiments are performed on ytterbium-doped silicate glass samples. A strong charge-transfer (CT) absorption band near 230nm in aluminosilicate glass is found to be correlated to the mechanism of induced color center formation. Excitation into the CT-absorption band generates similar color centers as observed in ytterbium-doped fiber lasers under 915nm high power diode pumping. The position of the CT-absorption band is compositional dependent and is shifted to shorter wavelengths in ytterbium doped phosphosilicate glass. Very low levels of photodarkening is observed for the ytterbium doped phosphosilicate glass composition under 915nm high power diode pumping. Possible excitation routes to reach the CT-absorption band under 915nm pumping are discussed.

  19. The role of water in the elastic properties of aluminosilicate zeolites: DFT investigation.

    PubMed

    Bryukhanov, Ilya A; Rybakov, Andrey A; Larin, Alexander V; Trubnikov, Dmitry N; Vercauteren, Daniel P

    2017-03-01

    The bulk and Young moduli and heats of hydration have been calculated at the DFT level for fully optimized models of all-siliceous and cationic zeolites with and without water, and then compared to the corresponding experimental data. Upon the addition of water, the monovalent alkali ion and divalent alkaline earth ion exchanged zeolites presented opposite trends in the elastic modulus. The main contribution to the decrease in the elastic modulus of the alkali ion exchanged zeolites appeared to be a shift of cations from the framework oxygen atoms upon water addition, with the coordination number often remaining the same. The contrasting increase in elastic modulus observed for the divalent (alkaline earth) ion exchanged zeolites was explained by cation stabilization resulting from increased coordination, which cannot be achieved within a rigid zeolite framework without water.

  20. A magneto-optical study of bismuth-doped MgO – Al2O3 – SiO2 glass: on the nature of near-infrared luminescence

    NASA Astrophysics Data System (ADS)

    Laguta, A. V.; Denker, B. I.; Sverchkov, S. E.; Razdobreev, I. M.

    2017-02-01

    This paper presents results of a detailed magneto-optical spectroscopy study of bismuth-doped aluminosilicate glass. At least three distinct optical centres are shown to coexist in the glass: bismuth ion clusters, Bi+ ions and defects in the glass structure, with energy transfer between the last two species. Analysis of magnetic circular dichroism and magnetic circular polarisation of luminescence as functions of magnetic field and temperature indicates that all three centres have an even number of electrons (holes). Experimental evidence is presented that both 'red' and near-infrared luminescence bands are due to transitions in the defects.