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Sample records for alkali silicate glasses

  1. Electric field-induced softening of alkali silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    McLaren, C.; Heffner, W.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Tessarollo, R.; Raj, R. [Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)

    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.

  2. Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

    OpenAIRE

    Lammert, Heiko; Heuer, Andreas

    2005-01-01

    The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed--alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronge...

  3. On the origin of the mixed alkali effect on indentation in silicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, J. C.;

    2014-01-01

    deformation processes (elastic deformation, plastic deformation, and densification) and Hv in two mixed sodium–potassium silicate glass series. We show that the mixed alkali effect in Hv originates from the nonlinear scaling of the resistance to plastic deformation. We thus confirm a direct relation between...

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

    Science.gov (United States)

    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).

  5. Electronic structure and Fano antiresonance of chromium Cr(III) ions in alkali silicate glasses

    International Nuclear Information System (INIS)

    The optical properties of the Cr3+ doped in alkali silicate glasses X2O–SiO2 with different modifier cations X=Li, Na and K have been investigated by Villian et al. This work investigates a theoretical crystal-field analysis of the electronic energy levels of Cr3+ in these glasses. This analysis based on the Racah theory was carried out for the Chromium (III) center with an Oh site symmetry. The objective of this study is to determine the effect of glass matrix modifier on the Racah B, C and crystal-field Dq parameters. The effect of the glass matrix environment on these parameters is also reported by comparison with alkali cadmium borosulphate, phosphate and borate glasses. The interference dips observed in the broad band 4T2g(4F) result from interaction with the 2Eg(2G) and 2T1g(2G) sharp levels are known as the Fano antiresonance model. This feature is qualitatively studied using the adiabatic potential surfaces for the quartet 4T2g(4F) and doublet 2Eg(2G) levels. - Highlights: • The electronic structure of Cr3+ in alkali silicate glasses X2O–SiO2 (X=Li,Na,K) was performed. • The theoretical study, based on Racah theory, permits us to deduce the energy levels. • The observed interference dip in absorption spectra is related to Fano antiresonance

  6. Structural analysis of alkali cations in mixed alkali silicate glasses by 23Na and 133Cs MAS NMR

    Directory of Open Access Journals (Sweden)

    T. Minami

    2014-12-01

    Full Text Available We report the structural analysis of Na+ and Cs+ in sodium cesium silicate glasses by using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR spectroscopy. In the NMR spectra of cesium silicate crystals, the peak position shifted to higher magnetic field for structures with larger Cs+ coordination numbers and to lower magnetic field for smaller Cs+ coordination numbers. The MAS NMR spectra of xNa2O-yCs2O-2SiO2 (x = 0, 0.2, 0.33, 0.5, 0.66, 0.8, 1.0; x + y = 1 glass reveal that the average coordination number of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+ ratio. In addition, the coordination number of Na+ in xNa2O-yCs2O-2SiO2 glass is smaller than that of Cs+. This difference between the average coordination numbers of the alkali cations is considered to be one structural reason of the mixed alkali effect.

  7. Electronic structure and Fano antiresonance of chromium Cr(III) ions in alkali silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Taktak, Olfa, E-mail: taktak.olfa@gmail.com; Souissi, Hajer; Souha, Kammoun

    2015-05-15

    The optical properties of the Cr{sup 3+} doped in alkali silicate glasses X{sub 2}O–SiO{sub 2} with different modifier cations X=Li, Na and K have been investigated by Villian et al. This work investigates a theoretical crystal-field analysis of the electronic energy levels of Cr{sup 3+} in these glasses. This analysis based on the Racah theory was carried out for the Chromium (III) center with an O{sub h} site symmetry. The objective of this study is to determine the effect of glass matrix modifier on the Racah B, C and crystal-field Dq parameters. The effect of the glass matrix environment on these parameters is also reported by comparison with alkali cadmium borosulphate, phosphate and borate glasses. The interference dips observed in the broad band {sup 4}T{sub 2g}({sup 4}F) result from interaction with the {sup 2}E{sub g}({sup 2}G) and {sup 2}T{sub 1g}({sup 2}G) sharp levels are known as the Fano antiresonance model. This feature is qualitatively studied using the adiabatic potential surfaces for the quartet {sup 4}T{sub 2g}({sup 4}F) and doublet {sup 2}E{sub g}({sup 2}G) levels. - Highlights: • The electronic structure of Cr{sup 3+} in alkali silicate glasses X{sub 2}O–SiO{sub 2} (X=Li,Na,K) was performed. • The theoretical study, based on Racah theory, permits us to deduce the energy levels. • The observed interference dip in absorption spectra is related to Fano antiresonance.

  8. Decay curve analysis of alkali-silicate glass exposed to electrons

    CERN Document Server

    Gedeon, O

    2002-01-01

    Binary and ternary potassium, rubidium and caesium glasses were irradiated by an electron beam with energy varying from 10 to 50 keV. Alkali ion x-ray decays were recorded and afterward incubation periods were determined. The incubation period versus electron energy curves revealed thresholds, which are typical for each alkali species. The threshold ratios are proportional to the mass of the alkali species, consistent with the suggested elastic scattering assisted hopping mechanism. (author)

  9. Alkali Silicate Glass Coatings for Mitigating the Risks of Tin Whiskers

    Science.gov (United States)

    Hillman, Dave; Wilcoxon, Ross; Lower, Nate; Grossman, Dan

    2015-12-01

    Alkali silicate glass (ASG) coatings were investigated as a possible method for inhibiting tin whisker initiation and growth. The aqueous-based ASG formulations used in this study were deposited with equipment and conditions that are typical of those used to apply conventional conformal coatings. Processes for controlling ASG coating properties were developed, and a number of ASG-based coating combinations were applied to test components with pure tin surfaces. Coatings were applied both in a laboratory environment at Rockwell Collins and in a manufacturing environment at Plasma Ruggedized Solutions. Testing in elevated humidity/temperature environments and subsequent inspection of the test articles identified coating combinations that inhibited tin whisker growth as well as other material combinations that actually accelerated tin whisker growth. None of the coatings evaluated in this study, including conventional acrylic and Parylene conformal coatings, completely prevented the formation of tin whiskers. Two of the coatings were particularly effective at reducing the risks of whisker growth, albeit through different mechanisms. Parylene conformal coating almost, but not completely, eliminated whisker formation, and only a few tin whiskers were found on these surfaces during the study. A composite of ASG and alumina nanoparticles inhibited whisker formation to a lesser degree than Parylene, but did disrupt whisker growth mechanisms so as to inhibit the formation of long, and more dangerous, tin whiskers. Additional testing also demonstrated that the conformal coatings had relatively little effect on the dielectric loss of a stripline test structure operating at frequencies over 30 GHz.

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

    Science.gov (United States)

    Jansson, Helén; Bernin, Diana; Ramser, Kerstin

    2015-06-01

    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 (29Si-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 CO2 footprint cements, i.e. materials based on industrial waste or by-products.

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

    Directory of Open Access Journals (Sweden)

    Helén Jansson

    2015-06-01

    Full Text Available 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 (29Si-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 CO2 footprint cements, i.e. materials based on industrial waste or by-products.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Helén, E-mail: helen.jansson@chalmers.se [Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Bernin, Diana, E-mail: diana.bernin@nmr.gu.se [Swedish NMR Centre, Gothenburg University, Gothenburg, 41390 Sweden (Sweden); Ramser, Kerstin, E-mail: kerstin.ramser@ltu.se [Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 87 Luleå (Sweden)

    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.

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

    Science.gov (United States)

    Chou, Yeong-Shyung; Thomsen, E. C.; Williams, R. T.; Choi, J.-P.; Canfield, N. L.; Bonnett, J. F.; Stevenson, J. W.; Shyam, A.; 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 cell (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 and 850 °C using back pressures ranging from 1.4 to 6.8 kPa (0.2-1.0 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.

  14. On the structure of defect centers in γ-irradiated alkali silicate glasses

    Science.gov (United States)

    Cases, R.; Griscom, D. L.

    1984-02-01

    An EPR study after room temperature γ-irradiation on potassium silicate glasses of two chemical compositions and different 17O and 29Si isotopic enrichments has been carried out. Isochronal anneal experiments on 17O-enriched samples have confirmed the model for the trapped-hole center HC 1 as comprising a trapped hole on a pure 2p π orbital of a single nonbridging oxygen. Besides the well known HC 1 and HC 2 EPR spectra, new resonances have been isolated and identified as due to three types of oxygen-related defects (interstitial O 2- ions; O 2- bonded to the glass network; and interstitial ozonide ions O 3-). Using 29Si-enriched samp simulations a 370 G doublet has been demonstrated to arise from an E'-like defect for which a tentative model is given. The formation of all these defects by irradiation depends on chemical composition of the glass.

  15. Multilevel Tunnelling Systems and Fractal Clustering in the Low-Temperature Mixed Alkali-Silicate Glasses

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    Giancarlo Jug

    2013-01-01

    Full Text Available 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 (SiO21−x(K2Ox and (SiO21−x(Na2Ox 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.

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

    Science.gov (United States)

    Jug, Giancarlo; Paliienko, Maksym

    2013-01-01

    The thermal and dielectric anomalies of window-type glasses at low temperatures (T 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. PMID:23861652

  17. Compliant alkali silicate sealing glass for solid oxide fuel cell applications: Combined stability in isothermal ageing and thermal cycling with YSZ coated ferritic stainless steels

    Science.gov (United States)

    Chou, Yeong-Shyung; Thomsen, E. C.; Choi, J.-P.; Stevenson, J. W.

    2012-01-01

    An alkali silicate glass (SCN-1) is being evaluated as a candidate sealant for solid oxide fuel cell (SOFC) applications. The glass contains about 17 wt.% alkalis (K + Na) and has low glass transition and softening temperatures. It remains vitreous and compliant after sealing without substantial crystallization, as contrary to conventional glass-ceramic sealant. The glassy nature and low characteristic temperatures can reduce residual stresses and result in the potential for crack healing. In a previous study, the glass was found to have good thermal cycle stability and was chemically compatible with yttria stabilized zirconia (YSZ) coating during short term testing. In this study, the compliant glass was further evaluated in a more realistic way in that the sealed couples were first isothermally aged for 1000 h followed by thermal cycling. High temperature leakage was measured. Chemical compatibility was also investigated with powder mixtures to enhance potential interfacial reaction. In addition, interfacial microstructure was examined with scanning electron microscopy and evaluated with regard to the leakage and chemical compatibility results. Overall the compliant sealing glass showed desirable chemical compatibility with YSZ coated metallic interconnect of minimum reaction and hermetic behavior at 700-750 °C in dual environment.

  18. Volume of ionic sites in silicate glasses

    International Nuclear Information System (INIS)

    Molar volume data of alkali and alkaline earth silicate glasses have been used to calculate the free volume associated with the bridging and nonbridging oxygen and modifier ions. The free volume associated with the bridging oxygen is constant (15.39 x 10-24 cm3) for all modifier ions up to 33.3 mol% modifier oxide. It decreases (in alkali or alkaline earth silicate glasses) with increasing number of nonbridging oxygen ions per structural unit and/or radius of the modifier ion. The nonbridging oxygen ion is associated with a constant free volume (6.50 x 10-24 cm3) in all cases. Modifier ions are associated with free volume that increases with increasing number of nonbridging oxygen ions per structural unit and/or radius of the modifier ion. The used model explores the change in the free volume due to changing the concentration of alkali oxides in mixed alkali silicate glasses. The results show that, in such glasses, the free volume related to a certain type of alkali oxide increases with increasing content

  19. Effects of ionization on silicate glasses. [Silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Primak, W.

    1982-02-01

    This evaluation of radiation effects in silicate glasses caused by ionization is based on our own investigations, on material collected in our files (reports, articles, and notes), and on a computer literature search through recent issues of Physics Abstracts and Chemical Abstracts (and the apparently pertinent references which appeared). Some of our recent results, available heretofore only in internal correspondence, are presented in some detail. It is concluded that research into the behavior of silicate glasses generally will be required before the specific effects in the radioactive waste storage glasses can be properly understood and evaluated. Two particular neglected areas of investigation are targeted for immediate concern: a kinetic analysis of annealing data and the acquisition of data on effects of irradiation at controlled elevated temperatures.

  20. EXAFS studies of sodium silicate glasses containing dissolved actinides

    International Nuclear Information System (INIS)

    Sodium silicate glasses containing dissolved Th, U, Np, and Pu have been studied using the EXAFS technique. Th4+, U4+, Np4+, and Pu4+ ions in the silicate glasses are 8-fold coordinated to oxygen neighbors. The higher valent U6+ and Np5+ ions have complex local symmetries. The U6+ ions appear in a uranyl configuration with 2 oxygen atoms at 1.85A and 4 at 2.25A from the U ion. The Np5+ local symmetry is more complex and difficult to determine uniquely. The U6+ glasses show substantial clustering of the uranium atoms. A structural model, with nearly planar uranyl sheets sandwiched between alkali and silica layers, is used to explain the U6+ EXAFS data. This model allows us to understand why U6+ ions are much more soluble in the glasses than the actinide 4+ ions. 4 references, 2 figures

  1. Calcium silicate hydrate: Crystallisation and alkali sorption

    International Nuclear Information System (INIS)

    Homogeneous single C-S-H gels has been prepared for the investigation of alkali binding potential and crystallisation. A distribution coefficient, Rd, was introduced to express the partition of alkali between solid and aqueous phases at 25 deg. C. Rd is independent of alkali hydroxide concentration and depends only on Ca:Si ratio over wide ranges of alkali concentration. The trend of numerical values of Rd indicates that alkali bonding into the solid improves as its Ca:Si ratio decreases. Reversibility is demonstrated, indicating a possibility of constant Rd value of the material. Al has been introduced to form C-A-S-H gels and their alkali sorption properties also determined. Al substituted into C-S-H markedly increases Rd, indicating enhancement of alkali binding. However, the dependence of Rd on alkali concentration is non-ideal with composition. A two-site model for bonding is presented. Crystallisation both under saturated steam and 1 bar vapour pressure has been investigated. It has been shown that heat treatment by saturated steam causes crystallisation of gels. The principal minerals obtained were (i) C-S-H gel and Ca(OH)2 at -55 deg. C, (ii) 1.1 nm tobermorite, jennite and afwillite at 85 -130 deg. C, and (iii) xonotlite, foshagite and hillebrandite at 150-180 deg. C. Properties of crystalline C-S-H were also reported for reversible phase transformation, pH conditioning ability, seeding effect and solubility. At 1 bar pressure, crystallisation is slower than in saturated steam due to lower water activity. Tobermorite-like nanodomains develop during reaction at low Ca/Si ratios. In some Ca-rich compositions, Ca(OH)2 is exsolved and occurs as nano-sized crystallites. (author)

  2. Local structure of alkalis in mixed-alkali borate glass to elucidate the origin of mixed-alkali effect

    Directory of Open Access Journals (Sweden)

    Yomei Tokuda

    2015-12-01

    Full Text Available We report the structural analysis of Na+ and Cs+ in sodium cesium borate crystals and glasses using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR spectroscopy. The composition dependence of NMR spectra of the borate was similar to that of the silicate: (1 the peak position of cesium borate crystals shifted to upfield for structures with larger Cs+ coordination numbers, (2 the MAS NMR spectra of xNa2O-yCs2O-3B2O3 (x = 0, 0.25, 0.5, 0.75, 1.0, x + y = 1 glass showed that the average coordination number (CN of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+ ratio. However, the degree of decrement in borates is much smaller than that in silicates. We have considered that the small difference in CN is due to 4-coordinated B, because it is electrically compensated by the alkali metal ions resulting in the restriction of having various coordinations of O to alkali metal.

  3. Density of mixed alkali borate glasses: A structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Doweidar, H. [Glass Research Group, Physics Department, Faculty of Science, Mansoura University, P.O. Box 83, Mansoura 35516 (Egypt)]. E-mail: hdoweidar@mans.edu.eg; El-Damrawi, G.M. [Glass Research Group, Physics Department, Faculty of Science, Mansoura University, P.O. Box 83, Mansoura 35516 (Egypt); Moustafa, Y.M. [Glass Research Group, Physics Department, Faculty of Science, Mansoura University, P.O. Box 83, Mansoura 35516 (Egypt); Ramadan, R.M. [Glass Research Group, Physics Department, Faculty of Science, Mansoura University, P.O. Box 83, Mansoura 35516 (Egypt)

    2005-05-15

    Density of mixed alkali borate glasses has been correlated with the glass structure. It is assumed that in such glasses each alkali oxide associates with a proportional quantity of B{sub 2}O{sub 3}. The number of BO{sub 3} and BO{sub 4} units related to each type of alkali oxide depends on the total concentration of alkali oxide. It is concluded that in mixed alkali borate glasses the volumes of structural units related to an alkali ion are the same as in the corresponding binary alkali borate glass. This reveals that each type of alkali oxide forms its own borate matrix and behaves as if not affected with the presence of the other alkali oxide. Similar conclusions are valid for borate glasses with three types of alkali oxide.

  4. Alkali-Activated Aluminium-Silicate Composites as Insulation Materials for Industrial Application

    Science.gov (United States)

    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.

  5. Compositional dependence of in vitro response to commercial silicate glasses

    Science.gov (United States)

    Jedlicka, Amy B.

    Materials are often incorporated into the human body, interacting with surrounding fluids, cells and tissues. The reactions that occur between a material and this surrounding biological system are not fundamentally understood. Basic knowledge of material biocompatibility and the controlling processes is lacking. This thesis examines material biocompatibility of a series of silicate-based glasses on a primary level determining cell response to material composition and durability. The silicate glass system studied included two BioglassRTM compositions with known biologically favorable response, two fiberglass compositions, with demonstrated 'not-unfavorable' in vitro response, a ternary soda-lime-silicate glass, a binary alkali silicate glass, and pure silica. Chemical durability was analyzed in three different fluids through solution analysis and material characterization. In vitro response to the substrates was observed. Cell behavior was then directly correlated to the material behavior in cell culture medium under the same conditions as the in vitro test, yet in the absence of cells. The effect of several physical and chemical surface treatments on substrates with predetermined biocompatible behavior was subsequently determined. The chemically durable glasses with no added B2O3 elicited similar cell response as the control polystyrene substrate. The addition of B2O3 resulted in polygonal cell shape and restricted cell proliferation. The non-durable glasses presented a dynamic surface to the cells, which did not adversely affect in vitro response. Extreme dissolution of the binary alkali silicate glass in conjunction with increased pH resulted in unfavorable cell response. Reaction of the Bioglass RTM compositions, producing a biologically favorable calcium-phosphate surface film, caused enhanced cell attachment and spreading. Surface energy increase due to sterilization procedures did not alter cellular response. Surface treatment procedures influencing substrate

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

    International Nuclear Information System (INIS)

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

  7. EXAFS studies of silicate glasses containing uranium

    International Nuclear Information System (INIS)

    Sodium silicate glasses containing hexavalent uranium ions have been studied using the EXAFS technique. The U6+ ions appear in the uranyl configuration with two oxygen atoms at 1.85 A and four to five at 2.2-2.3 A. In the glasses (0.25Na2O.0.75SiO2)sub(1-x)(UO3)sub(x) with x = 0.02 to x = 0.1, planar (or nearly planar) uranium containing clusters, with U-U distances of 3.3 A, are observed. A layered model is proposed to describe these glasses. (Auth.)

  8. Cooling rate calculations for silicate glasses.

    Science.gov (United States)

    Birnie, D. P., III; Dyar, M. D.

    1986-03-01

    Series solution calculations of cooling rates are applied to a variety of samples with different thermal properties, including an analog of an Apollo 15 green glass and a hypothetical silicate melt. Cooling rates for the well-studied green glass and a generalized silicate melt are tabulated for different sample sizes, equilibration temperatures and quench media. Results suggest that cooling rates are heavily dependent on sample size and quench medium and are less dependent on values of physical properties. Thus cooling histories for glasses from planetary surfaces can be estimated on the basis of size distributions alone. In addition, the variation of cooling rate with sample size and quench medium can be used to control quench rate.

  9. Effects of ionization on silicate glasses

    International Nuclear Information System (INIS)

    This evaluation of radiation effects in silicate glasses caused by ionization is based on our own investigations, on material collected in our files (reports, articles, and notes), and on a computer literature search through recent issues of Physics Abstracts and Chemical Abstracts (and the apparently pertinent references which appeared). Some of our recent results, available heretofore only in internal correspondence, are presented in some detail. It is concluded that research into the behavior of silicate glasses generally will be required before the specific effects in the radioactive waste storage glasses can be properly understood and evaluated. Two particular neglected areas of investigation are targeted for immediate concern: a kinetic analysis of annealing data and the acquisition of data on effects of irradiation at controlled elevated temperatures

  10. The structure of alkali silicate gel by total scattering methods

    KAUST Repository

    Benmore, C.J.

    2010-06-01

    The structure of the alkali silicate gel (ASR) collected from the galleries of Furnas Dam in Brazil was determined by a pair distribution function (PDF) analysis of high energy X-ray diffraction data. Since this method is relatively new to concrete structure analysis a detailed introduction on the PDF method is given for glassy SiO2. The bulk amorphous structure of the dam material is confirmed as no Bragg peaks are observed in the scattered intensity. The real space results show that the local structure of the amorphous material is similar to kanemite (KHSi2O5:3H2O) however the long range layer structure of the crystal is broken up in the amorphous state, so that ordering only persists of the length scale of a few polyhedra. The silicate layer structure is a much more disordered than predicted by molecular dynamics models. The X-ray results are consistent with the molecular dynamics model of Kirkpatrick et al. (2005) [1] which predicts that most of the water resides in pores within the amorphous network rather than in layers. The total scattering data provide a rigorous basis against which other models may also be tested. © 2010.

  11. Radiation effects on lead silicate glass surfaces

    International Nuclear Information System (INIS)

    Radiation-induced changes in the microstructure of lead silicate glass were investigated in situ under Mg Kα irradiation in an ultra-high vacuum (UHV) environment by X-ray photoelectron spectroscopy (XPS). Lead-oxygen bond breaking resulting in the formation of pure lead was observed. The segregation, growth kinetics and the structural relaxation of the lead, with corresponding changes in the oxygen and silicon on the glass surfaces were studied by measuring the time-dependent changes in concentration, binding energy shifts, and the full width at half maximum. A bimodal distribution of the oxygen XPS signal, caused by bridging and non-bridging oxygens, was found during the relaxation process. All experimental data indicate a reduction of the oxygen concentration, a phase separation of the lead from the glass matrix, and the metallization of the lead occurred during and after the X-ray irradiation. (author)

  12. Raman spectra and structure study of silicate glasses and their liquids

    Institute of Scientific and Technical Information of China (English)

    YOU Jinglin; JIANG Guochang; CHEN Hui; XU Kuangdi

    2006-01-01

    Stress index of tetrahedron (SIT) was defined to describe the topological connectivities among various silicon-oxygen tetrahedra (SiOT) in anionic clusters of binary silicate crystals, glasses, and melts. It was found that the value of SIT was well correlated with the wavenumber of Raman active symmetric stretching vibration of non-bridging oxygen of SiOT. The spatial fractional dimension of hyperfine structure was introduced while comparative analysis was made with the value of SIT. It can be concluded that the concepts of SIT, vibrational wavenumber, and spatial fractional dimension were inherently and holographically correlated and exhibit isomorphic representations of complex structure of binary silicates.Experimental Raman spectra of binary silicates with different alkali cations were investigated. It was demonstrated that alkali cations have little effect on the vibrational wavenumber of symmetric stretching of non-bridging oxygen (NBO) of SiOT, but remarkably affect its Raman active optical cross section, as was consensus resulted from ab initio calculation. It can also be concluded that the spatial fractional dimension of binary silicate is predominantly determined by the hyperfine structure of the anionic clusters and little affected by alkali cations, although the species of anionic clusters and their distributions were originally assigned by the content of alkali oxides. And Raman optical activity extinct effect of isolated SiOT at high basicity should be considered while being applied to quantitatively analysis.

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

    Science.gov (United States)

    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. PMID:25280692

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

    Energy Technology Data Exchange (ETDEWEB)

    Kansal, Ishu; Reddy, AlluAmarnath [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Muñoz, Francisco [Ceramics and Glass Institute (CSIC), Kelsen 5, 28049 Madrid (Spain); Choi, Seong-Jun [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Kim, Hae-Won [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330714 (Korea, Republic of); Tulyaganov, Dilshat U. [Turin Polytechnic University in Tashkent, 100095 Tashkent (Uzbekistan); Ferreira, José M.F., E-mail: jmf@ua.pt [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO–MgO–SiO{sub 2}–P{sub 2}O{sub 5}–CaF{sub 2} system. The {sup 29}Si and {sup 31}P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na{sub 2}O/MgO ratios exhibit a silicate glass network with the dominance of Q{sup 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 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na{sup +}/Mg{sup 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. - Highlights: • Na{sup +} did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na{sup +}/Mg{sup 2+} ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium.

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

    International Nuclear Information System (INIS)

    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 29Si and 31P 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 Q2(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 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na+/Mg2+ 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. - Highlights: • Na+ did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na+/Mg2+ ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium

  16. Optical and crystallization studies of titanium dioxide doped sodium and potassium silicate glasses

    Science.gov (United States)

    ElBatal, F. H.; Marzouk, M. A.; ElBatal, H. A.

    2016-10-01

    Combined optical and FTIR spectral analysis were used to investigate prepared invert two alkali silicate glasses (Na2O·SiO2sbnd K2O·SiO2) containing high titanium oxide content. Glass ceramic derivatives were prepared through thermal two step regime of the parent glasses and they were characterized by FTIR and X-ray diffraction measurements. Experimental optical spectra indicate the appearance of an additional UV band due to absorption of tetravalent titanium ions beside the UV bands due to trace ferric ions impurities. FT infrared absorption spectra reveal composite vibrational bands due to vibrational modes of both silicate groups and TiO4 or Sisbnd Osbnd Ti units. Such tetravalent groupings of titanium ions confirm the stability of such invert glasses containing as such two main glass forming oxides. FTIR spectra of the glass - ceramic derivatives show nearly the same IR vibrational modes as their parent glasses. X-ray diffraction analysis show the separation of crystalline sodium or potassium titanate phases beside a minor form of silica and the results confirm that TiO2 acts mainly as network forming units leading to the formation of crystalline titanate phases.

  17. Calorimetric signature of structural heterogeneity in a ternary silicate glass

    DEFF Research Database (Denmark)

    Zhang, Yanfei; Yang, G.; Yue, Yuanzheng

    2013-01-01

    We investigate the structural heterogeneity in a silicate glass by hyperquenching–annealing–calorimetry approach. The results show a striking phenomenon: two separated sub-Tg relaxation peaks appear on the calorimetric curve of the hyperquenched CaO–MgO–SiO2 glass, implying the existence of two...

  18. Are the dynamics of silicate glasses and glass-forming liquids embedded in their elastic properties?

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Mauro, John C.

    According to the elastic theory of the glass transition, the dynamics of glasses and glass-forming liquids are controlled by the evolution of shear modulus. In particular, the elastic shoving model expresses dynamics in terms of an activation energy required to shove aside the surrounding atoms, ...... of the silicate glass transition are governed by additional factors beyond the evolution of the shear modulus....

  19. Nanoscale Charge Balancing Mechanism in Alkali Substituted Calcium-Silicate-Hydrate Gels

    CERN Document Server

    Özçelik, V Ongun

    2016-01-01

    Alkali-activated materials and related alternative cementitious systems are sustainable material technologies that have the potential to substantially lower CO$_2$ emissions associated with the construction industry. However, the impact of augmenting the chemical composition of the material on the main binder phase, calcium-silicate-hydrate gel, is far from understood, particularly since this binder phase is disordered at the nanoscale. Here, we reveal the presence of a charge balancing mechanism at the molecular level, which leads to stable structures when alkalis (i.e., Na or K) are incorporated into a calcium-silicate-hydrate gel, as modeled using crystalline 14{\\AA} tobermorite. These alkali containing charge balanced structures possess superior mechanical properties compared to their charge unbalanced counterparts. Our results, which are based on first-principles simulations using density functional theory, include the impact of charge balancing on the optimized geometries of the new model phases, format...

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

    International Nuclear Information System (INIS)

    The mixed alkali effect on zinc borate glasses have been reported. The glass systems of nominal composition 10Zn+xLi2O+yNa2O+80B2O3 (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 (Li2O and Na2O) 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 (BO4/2)− into (BO3/2)−. The microhardness studies reveals the anisotropy nature of the material. It further confirms that the samples belong to hard glass category

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

    Science.gov (United States)

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

    2014-04-01

    The mixed alkali effect on zinc borate glasses have been reported. The glass systems of nominal composition 10Zn+xLi2O+yNa2O+80B2O3 (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 (Li2O and Na2O) 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 (BO4/2)- into (BO3/2)-. The microhardness studies reveals the anisotropy nature of the material. It further confirms that the samples belong to hard glass category.

  2. Durability of Silicate Glasses: An Historical Approach

    Energy Technology Data Exchange (ETDEWEB)

    Farges, Francois; /Museum Natl. Hist. Natur. /Stanford U., Geo. Environ. Sci.; Etcheverry, Marie-Pierre; /Marne la Vallee U.; Haddi, Amine; /Marne la Valle U.; Trocellier,; /Saclay; Curti, Enzo; /PSI, Villigen; Brown, Gordon E., Jr.; /SLAC, SSRL

    2007-01-02

    We present a short review of current theories of glass weathering, including glass dissolution, and hydrolysis of nuclear waste glasses, and leaching of historical glasses from an XAFS perspective. The results of various laboratory leaching experiments at different timescales (30 days to 12 years) are compared with results for historical glasses that were weathered by atmospheric gases and soil waters over 500 to 3000 years. Good agreement is found between laboratory experiments and slowly leached historical glasses, with a strong enrichment of metals at the water/gel interface. Depending on the nature of the transition elements originally dissolved in the melt, increasing elemental distributions are expected to increase with time for a given glass durability context.

  3. High-Q bismuth silicate nonlinear glass microsphere resonators

    OpenAIRE

    Wang, Pengfei; Murugan, Ganapathy; Lee, Timothy; Ding, Ming; Brambilla, Gilberto; Semenova, Yuliya; Wu, Qiang; Koizumi,Fumihito; Farrell, Gerald

    2012-01-01

    The fabrication and characterization of a bismuth-silicate glass microsphere resonator has been demonstrated. At wavelengths near 1550 nm, high-modes can be efficiently excited in a 179-μm diameter bismuth-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of circa 2 μm. Resonances with Q-factors as high as were observed. The dependence of the spectral response on variations in the input power level was studied in detail to gain an insight in...

  4. Lead Silicate Glass Microsphere Resonators With Absorption-Limited Q

    OpenAIRE

    Wang, Pengfei; Murugan, Genapathy; Lee, Timothy; Feng, Xian; Semenova, Yuliya; Wu, Qiang; Loh, Wei; Brambilla, Gilberto; Wilkinson, James; Farrell, Gerald

    2011-01-01

    We report the fabrication and characterization of a lead-silicate glass microsphere resonator. We show that at the wavelengths near 1555 nm high Q modes can be efficiently excited from a 109 μm diameter lead-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of 2 μm. Resonances with Q-factors as high as 0.9×107 were observed. This is very close to the theoretical material-limited Q-factor and is the highest Q-factor reported so far from a non...

  5. Low-frequency Raman scattering in alkali tellurite glasses

    Indian Academy of Sciences (India)

    Angelos G Kalampounias

    2008-10-01

    Raman scattering has been employed to study the alkali-cation size dependence and the polarization characteristics of the low-frequency modes for the glass-forming tellurite mixtures, 0.1M2O–0.9TeO2 (M = Na, K, Rb and Cs). The analysis has shown that the Raman coupling coefficient alters by varying the type of the alkali cation. The addition of alkali modifier in the tellurite network leads to the conversion of the TeO4 units to TeO3 units with a varying number of non-bridging oxygen atoms. Emphasis has also been given to the lowfrequency modes and particular points related to the low-frequency Raman phenomenology are discussed in view of the experimental findings.

  6. Modifier constraints in alkali ultraphosphate glasses

    DEFF Research Database (Denmark)

    Rodrigues, B.P.; Mauro, J.C.; Yue, Yuanzheng;

    2014-01-01

    In applying the recently introduced concept of cationic constraint strength [J. Chem. Phys. 140, 214501 (2014)] to bond constraint theory (BCT) of binary phosphate glasses in the ultraphosphate region of xR2O-(1-x)P2O5 (with x ≤ 0.5 and R = {Li, Na, Cs}), we demonstrate that a fundamental...... limitation of BCT can be overcome. The modifiers are considered to exist in either “isolated” or “crosslinking” sites, in line with the so-called modifier sub-network [J. Chem. Phys. 140, 154501 (2014)] and each site is associated with a certain number of constraints. We estimate the compositional dependence...

  7. Nd3+ Doped Silicate Glass Photonic Crystal Fibres

    Institute of Scientific and Technical Information of China (English)

    YANG Lu-Yun; CHEN Dan-Ping; XIA Jin-An; WANG Chen; JIANG Xiong-Wei; ZHU Cong-Shan; QIU Jian-Rong

    2005-01-01

    @@ We report on the fabrication of two kinds of large core area Nd3+ doped silicate glass photonic crystal fibres, and demonstration of the fibre waveguiding properties. The measured minimum loss of one kind ofibres is 2.5 db/m at 660nm. The fibres sustain only a single mode at least over the wavelength range from 660nm to 980nm.

  8. A-thermal elastic behavior of silicate glasses.

    Science.gov (United States)

    Rabia, Mohammed Kamel; Degioanni, Simon; Martinet, Christine; Le Brusq, Jacques; Champagnon, Bernard; Vouagner, Dominique

    2016-02-24

    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 Si(4+) ions by Al(3+) 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. PMID:26815634

  9. Hardness and incipient plasticity in silicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.;

    2014-01-01

    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)...

  10. Femtosecond Laser Induced Rewritable Optical Memory in Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiongwei; QIU Jianrong; ZHU Congshan; K.Hirao; GAN Fuxi

    2001-01-01

    A novel method for producing rewritable optical memory with ultra-high storage density and ultra-high recording and readout speed is presented. A 120 fs, 800 nm, 1 kHz laser focused by an objective lens is used to produce recording bits in glass with high transmittance contrast. These recording bits can be erased by heat-treatment. The mechanism has been discussed by means of the absorption and electron spin resonance(ESR) spectra of silicate glasses before and after irradiation by the laser. The absorption of glasses increases greatly after irradiation because of color-center generation through multi-photon absorption. ESR spectra shows that the color-center induced in the glass are hole-trapped defects. The color-center disappears when the glass heated because the holes and electrons at traps are released by thermal stimulation and recombine again.

  11. Potassium-silicate glass exposed to low energy H+ beam

    International Nuclear Information System (INIS)

    Highlights: ► Pristine potassium-silicate glass was irradiated with 5 keV protons. ► Surface relaxation increases amount of K and NBO in the surface layer. ► Enhanced bombardment leads to a continuous decrease of NBO and K. ► A constant surplus of K in elemental state was found on the glass surface. - Abstract: Pristine surface of binary potassium silicate glass 85SiO2·15K2O was prepared in vacuum and irradiated with a 5 keV proton beam within the range of 0.6–103 C/m2. The response of glass surface was monitored by XPS and the evolution of atomic concentrations divided it into two stages. During the first one, amounts of both potassium and non-bridging oxygen (NBO) increase in the surface layer and are governed by surface relaxation. The second stage is characterised by a continuous decrease of NBO and K. Comparison of K and NBO concentrations yielded a constant surplus of K proving the existence of potassium elemental state on the glass surface. Ratio of bridging oxygen (BO) and silicon is conserved during proton bombardment. The extrapolation of the glass response to the enhanced irradiation predicts a formation of substoichiometric SiOx with some elemental K on the topmost surface.

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

    Energy Technology Data Exchange (ETDEWEB)

    Subhashini,, E-mail: subhashini.p.p@gmail.com; Bhattacharya, Soumalya, E-mail: subhashini.p.p@gmail.com; Shashikala, H. D., E-mail: subhashini.p.p@gmail.com; Udayashankar, N. K., E-mail: subhashini.p.p@gmail.com [Department of Physics, National Institute of Technology Karnataka, Surathkal-575025 (India)

    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.

  13. Structural changes between soda-lime silicate glass and melt

    International Nuclear Information System (INIS)

    Neutron diffraction has been used to study the structure of a glass and melt of composition 75SiO2-15Na2O-10CaO. RMC modeling of the neutron and X-ray diffraction data for the glass allowed the determination of the Na and Ca environment. The structure has been investigated at 300 K, just below the glass transition at 823 K and in the melt at 1273 K. The short range order does not present important modifications with temperature while significant reorganization appears at the medium range order. These latter changes can be associated with the Si and O pairs and indicate the relaxation of the silicate network. This indicates that the glass formation involved structural rearrangement during cooling. (authors)

  14. Concentration Quenching in Erbium Doped Bismuth Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    DAI Shi-Xun; XU Tie-Feng; NIE Qiu-Hua; SHEN Xiang; WANG Xun-Si

    2006-01-01

    @@ Er2 O3-doped bismuth silicate glasses are prepared by the conventional melt-quenching method, and the Er3+ : 4 I13/2 → 4I15/2 fluorescence properties are studied for different Er3+ concentrations. Infrared spectra are measured to estimate the exact content of OH- groups in the samples. Based on the electric dipole-dipole interaction theory,the interaction parameter CEr,Er for the migration rate of Er3+ :4 I13/2 → 4 I13/2 in proposed glasses is calculated.

  15. Tin in silicate glasses: structure, thermodynamics and kinetics

    International Nuclear Information System (INIS)

    In this work Moessbauer spectroscopy is used to investigate the oxidation states and structures of tin in silicate glasses. Thermal treatment of the glasses in atmospheres with varying oxygen partial pressure leads to the simultaneous appearance of reduction and diffusion. Experiments with varying treatment time give the opportunity to study diffusion and reduction processes in detail. Comparison of the hyperfine parameters of reference materials with measured parameter provides information about the local surroundings of the tin atoms. An octahedral surrounding for Sn4+ is presumed, while Sn2+ and three oxygen atoms form a tetrahedral coordination.

  16. Coloration processes in soda-lime silicate glasses

    International Nuclear Information System (INIS)

    The effect of mechanical stretching upon room temperature γ coloration of soda-lime silicate (SLS) glasses has been investigated. Optical absorption measurements were performed to follow the formation and thermal bleaching of the induced color centers. It has been shown that the mechanical deformation reduces the coloration effectivity and thermal stability of the created centers. It has been proposed that increase of the concentration of the non-bridging oxygens accelerate the bleaching processes

  17. Fluorescence properties of Eu3+-doped alumino silicate glasses

    Science.gov (United States)

    Herrmann, Andreas; Kuhn, Stefan; Tiegel, Mirko; Rüssel, Christian

    2014-11-01

    Alumino silicate glasses of a very broad range of molar compositions doped with 1 ṡ 1020 Eu3+ cm-3 (about 0.2 mol% Eu2O3) were prepared. As network modifier oxides Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, ZnO, PbO, Y2O3 and La2O3 have been used. All glasses show relatively broad fluorescence excitation and emission spectra. For most glasses only a weak effect of the glass composition on the excitation and emission spectra is observed. Although the glasses should be structurally similar, notable differences are found for the fluorescence lifetimes. These increase steadily with decreasing mean atomic weight, decreasing refractive index and decreasing optical basicity of the glasses, which may be explained by local field effects. An exception from this rule are the strontium, barium and potassium containing glasses, which show significantly increased fluorescence lifetimes despite of their high refractive index, optical basicity and molecular weight. The non mono-exponential fluorescence decay curves as well as the fluorescence spectra indicate a massive change in the local surroundings of the doped rare earth ions for these glasses.

  18. Influence of TiO2 on the Alkali Resistance and Structure of Invert Glass

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qing-lin; WU Zheng-ming; BU Heng-zhi

    2003-01-01

    Through measuring the alkali resistance of the invert glass and the quantity of SiO2 and TiO2 migrating fron the glass into the solution,the influence of TiO2 on the alkali resistance of the glass is discussed and its structure is also analyzed by infrared spectroscopy.It is concluded that TiO2 has double functions for the alkali resistance of the invert glass.On the one hand ,both TiO2 polarizing the secondary ions in glass and TiO2 isomorphism replacement of SiO2 make the alkali resistance of the glass decrease.On the ther hand,TiO2 patching network and anti-erosion covering help to increase the alkali resistance.

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

    Science.gov (United States)

    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).

  20. Conduction mechanism in bismuth silicate glasses containing titanium

    Science.gov (United States)

    Dult, Meenakshi; Kundu, R. S.; Murugavel, S.; Punia, R.; Kishore, N.

    2014-11-01

    Bismuth silicate glasses mixed with different concentrations of titanium dioxide having compositions xTiO2-(60-x)Bi2O3-40SiO2 with x=0, 5, 10, 15 and 20 were prepared by the normal melt quench technique. The frequency dependence of the ac electrical conductivity of different compositions of titanium bismuth silicate glasses has been studied in the frequency range 10-1 Hz to 10 MHz and in the temperature range 623-703 K. The temperature and frequency dependent conductivity is found to obey Jonscher's universal power law for all the compositions of titanium bismuth silicate glass system. The dc conductivity (σdc), so called crossover frequency (ωH), and frequency exponent (s) have been estimated from the fitting of experimental data of ac conductivity with Jonscher's universal power law. Enthalpy to dissociate the cation from its original site next to a charge compensating center (Hf) and enthalpy of migration (Hm) have also been estimated. The conductivity data have been analyzed in terms of different theoretical models to determine the possible conduction mechanism. Analysis of the conductivity data and the frequency exponent shows that the correlated barrier hopping of electrons between Ti3+ and Ti4+ ions in the glasses is the most favorable mechanism for ac conduction. The temperature dependent dc conductivity has been analyzed in the framework of theoretical variable range hopping model (VRH) proposed by Mott which describe the hopping conduction in disordered semiconducting systems. The various polaron hopping parameters have also been deduced. Mott's VRH model is found to be in good agreement with experimental data and the values of inverse localization length of s-like wave function (α) obtained by this model with modifications suggested by Punia et al. are close to the ones reported for a number of oxide glasses.

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

    Science.gov (United States)

    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.

  2. Optically stimulated luminescence and thermoluminescence in some Cu+ doped alkali fluoro-silicates

    International Nuclear Information System (INIS)

    OSL and TL in some Cu doped alkali fluoro-silicates were studied. These investigations show that the materials possess good OSL properties and the sensitivity is comparable to that of the commercial α-Al2O3:C phosphor. Of the several fluoro-silicate phosphors studied Cu doped Na2SiF6 is found to be highly sensitive. The initial OSL intensity averaged over first second using blue and green light stimulation, were found to be 1.2 and 13.3 times respectively of Al2O3:C. The simple preparation procedure, high OSL sensitivity, fast decay, and high photoionization cross-section will make these phosphors suitable for on-line radiation dosimetry, particularly in medical dosimetry applications. -- Highlights: • Intense TL and OSL in Cu doped Alkali fluorosilicates was observed. • The OSL sensitivity is comparable to commercial Al2O3:C (Landauer). • The phosphor possesses fast OSL decay, high sensitivity moderate to high fading. • These phosphors are more suitable for online radiation dosimetry using OSL

  3. Spectroscopic study of silicate glass structure. Application to the case of iron and magnesium

    International Nuclear Information System (INIS)

    During the last 10 years, I focused my research topics on silicate glass structure. More specifically I have been interested by two main components of natural and technological silicate glasses, Fe and Mg. Using solid state spectroscopic methods adapted to the disordered nature of glass coupled to molecular dynamics simulation and modeling or ab initio calculation, I have studied the environment of iron and magnesium and their impact on glass properties. Information on the distribution of environments in glasses have been extracted. (author)

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

    Science.gov (United States)

    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.

  5. SON68 glass dissolution driven by magnesium silicate precipitation

    Science.gov (United States)

    Fleury, Benjamin; Godon, Nicole; Ayral, André; Gin, Stéphane

    2013-11-01

    Experimental results are reported on the effect of magnesium silicate precipitation on the mechanisms and rate of borosilicate glass dissolution. Leaching experiments with SON68 glass, a borosilicate containing no Mg, were carried out in initially deionized water at 50 °C with a glass-surface-area-to-solution-volume ratio of 20,000 m-1. After 29 days of alteration the experimental conditions were modified by the addition of Mg to trigger the precipitation of Mg-silicate. Additional experiments were conducted to investigate the importance of other parameters such as pH or dissolved silica on the mechanisms of precipitation of Mg-silicates and their consequences on the glass dissolution rate. Mg-silicates precipitate immediately after Mg is added. The amount of altered glass increases with the quantity of added Mg, and is smaller when silicon is added in solution. A time lag is observed between the addition of magnesium and the resumption of glass alteration because silicon is first provided by partial dissolution of the previously formed alteration gel. It is shown that nucleation does not limit Mg-silicate precipitation. A pH above 8 is necessary for the phase to precipitate under the investigated experimental conditions. On the other hand the glass alteration kinetics limits the precipitation if the magnesium is supplied in solution at a non-limiting rate. The concentration of i in solution was analyzed as well as that of boron. The quantity of i released from the glass is estimated with the assumption that i and B are released congruently at the glass dissolution front. The remained quantity of the element i is then supposed to be in the gel or in the secondary phase. In this paper, we do not make a difference between gel and hydrated glass using the same word 'gel' whereas Gin et al. [40] makes this difference. Recent papers [40,41] discussed about different key issues related to the passivation properties of the alteration layer including the hydrated glass

  6. Experimental determination of partition coefficients for Rb, Sr, and Ba between alkali feldspar and silicate liquid

    International Nuclear Information System (INIS)

    Partitioning of Rb, Sr and Ba between alkali feldspar and a synthetic granitic melt has been determined at 8 kb and 720 to 7800C for a single quaternary granite composition. The results suggest that Henry's Law is obeyed by Rb up to approximately 0.8 wt.%Rb2O in both the liquid and in the alkali feldspar. The measured D values for Rb range from 0.77 to 1.1 For Ba, Henry's Law is obeyed up to approximately 0.6 wt.% BaO in the liquid and approximately 5 wt.% BaO in the alkali feldspar. D values for Ba range from 6.4 to 14. For Sr there is only a crude relationship between concentration in the liquid and concentration in the alkali feldspar at concentrations greater than approximately 0.6wt.%SrO in the liquid and approximately 0.4 wt.% SrO in the alkali feldspar. D values for Sr range from 1.2 to 5.0. Partitioning of Sr is apparently sensitive to the concentration of Ba in the system and this partly explains the failure of Sr to obey Henry's Law. Linear least-squares fits to the partitioning data as a function of temperature suggest inverse correlation between temperature and D values. Rb shows only a slight temperature effect whereas Ba and Sr appear to be rather strongly affected by temperature, but the temperature range examined here is small compared to the scatter in the data making these trends relatively uncertain. Other factors that appear to affect partitioning, especially of Sr, are growth rate, development of sector zoning, and Or content of the alkali feldspar. These factors severely limit the use of partitioning of these elements in alkali feldspar as geothermometers. The technique for measuring growth rates utilized here combined with measurement of trace element depletion in diffusion boundary layers adjacent to the alkali feldspar crystals makes it possible to estimate diffusivities for Ba and Sr. These estimates suggest a difference of 2 orders of magnitude between diffusivities for Ba and Sr in a vapor-saturated melt and those measured for a dry

  7. Cracking phenomena in lithium-di-silicate glass ceramics

    Indian Academy of Sciences (India)

    Rajat Banerjee

    2001-04-01

    Lithium-di-silicate glass ceramic (Li2O, SiO2) with uniformly oriented crystals was placed on a Vickers indentation with extrusion axis horizontally parallel to the base axis. The material was rotated through 0°– 90° and at each angle a 20 N load was applied to ascertain the crack path. It was observed that the crack length decreases and the crack deviates from its original path with increasing angle. The deviation of the crack was correlated with the component of the crack driving force and the theoretical strength of the aligned crystals at different angles.

  8. Infrared Spectroscopy and Stable Isotope Geochemistry of Hydrous Silicate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stolper, Edward

    2007-03-05

    The focus of this DOE-funded project has been the study of volatile components in magmas and the atmosphere. Over the twenty-one year period of this project, we have used experimental petrology and stable isotope geochemistry to study the behavior and properties of volatile components dissolved in silicate minerals and melts and glasses. More recently, we have also studied the concentration and isotopic composition of CO2 in the atmosphere, especially in relation to air quality issues in the Los Angeles basin.

  9. Analysis of an altered simple silicate glass using different mineral and glass standards

    International Nuclear Information System (INIS)

    Quantitative analyses of alteration products formed during the aqueous corrosion of glass were performed using four different sets of standards: relevant mineral standards, an NBS glass standard, and the unreacted center of the reacted glass. A simple silicate glass (containing Na, Mg, Al, Si, and Ca) was reacted in water vapor at 200/degree/C for 14 days. Up to eight alteration phases, including a Mg-rich smectite clay and a zeolite intermediate in composition between Ca-harmotome and phillipsite, formed on the glass surface. A set of EDS spectra of the bulk glass, the clay, and the zeolite were collected from a polished cross-section of the reacted sample. Results are discussed. 6 refs., 2 figs., 3 tabs

  10. Enzyme stabilization by glass-derived silicates in glass-exposed aqueous solutions

    Science.gov (United States)

    Ives, J.A.; Moffett, J.R.; Arun, P.; Lam, D.; Todorov, T.I.; Brothers, A.B.; Anick, D.J.; Centeno, J.; Namboodiri, M.A.A.; Jonas, W.B.

    2010-01-01

    Objectives: To analyze the solutes leaching from glass containers into aqueous solutions, and to show that these solutes have enzyme activity stabilizing effects in very dilute solutions. Methods: Enzyme assays with acetylcholine esterase were used to analyze serially succussed and diluted (SSD) solutions prepared in glass and plastic containers. Aqueous SSD preparations starting with various solutes, or water alone, were prepared under several conditions, and tested for their solute content and their ability to affect enzyme stability in dilute solution. Results: We confirm that water acts to dissolve constituents from glass vials, and show that the solutes derived from the glass have effects on enzymes in the resultant solutions. Enzyme assays demonstrated that enzyme stability in purified and deionized water was enhanced in SSD solutions that were prepared in glass containers, but not those prepared in plastic. The increased enzyme stability could be mimicked in a dose-dependent manner by the addition of silicates to the purified, deionized water that enzymes were dissolved in. Elemental analyses of SSD water preparations made in glass vials showed that boron, silicon, and sodium were present at micromolar concentrations. Conclusions: These results show that silicates and other solutes are present at micromolar levels in all glass-exposed solutions, whether pharmaceutical or homeopathic in nature. Even though silicates are known to have biological activity at higher concentrations, the silicate concentrations we measured in homeopathic preparations were too low to account for any purported in vivo efficacy, but could potentially influence in vitro biological assays reporting homeopathic effects. ?? 2009 The Faculty of Homeopathy.

  11. XPS study of CaO in sodium silicate glass

    International Nuclear Information System (INIS)

    This paper shows that CaO added to silicate glasses behaves much like Na2O in converting bridging oxygen sites to nonbridging sites. Good correspondence with model predictions was obtained but deviations were still sufficiently large to warrant attention. We speculate that some CaO may remain unreacted or that small-scale phase separation may occur. XPS core level shifts were monitored and possible charge-transfer effects were considered. Preliminary theoretical calculations utilizing a molecular-cluster approach were presented. XPS spectra for various glass compositions were simulated by appropriately combining local densities of state calculated for individual atoms. Dominant spectral features observed experimentally were found in the simulations. In conjunction with experiments, more carefully refined calculations will be subsequently examined. 7 figures

  12. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates.

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations' setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05). PMID:26787304

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

    Energy Technology Data Exchange (ETDEWEB)

    Verdolotti, Letizia; Capasso, Ilaria; Lavorgna, Marino [Institute of Composite and Biomedical Materials, National Research Council, Naples (Italy); Liguori, Barbara; Caputo, Domenico [Department of Chemical, Materials and Industrial Engineering, University of Naples Federico II, Naples (Italy); Iannace, Salvatore [Institute of Composite and Biomedical Materials, National Research Council, Naples, Italy and IMAST SCRAL, Piazza Bovio 22 Napoli 80133 (Italy)

    2014-05-15

    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/m{sup 3}) 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.

  14. Quantum-dot composite silicate glasses obtained by ion implantation

    International Nuclear Information System (INIS)

    Ion implantation is a useful technique to obtain composite materials such as nanocluster-containing silicate glasses. Depending on the choice of the pair 'implanted atom-dielectric host', ion implantation of metals in glass gives rise to the formation of new compounds and/or metallic nanoparticles. In spite of the great interest, processes governing the chemical and physical interaction between the implanted atoms and the atoms in the host matrix are not completely understood. In this paper, metal, alloy and binary compound nanocluster formation is studied after ion implantation in silica and soda-lime glass. Particular emphasis is given to the comparison among different existing approaches to the understanding of the chemical interactions in these systems. As the physical properties of these composites depend on the cluster structure, composition and size, it is important to set procedures for modifying these characteristics. Recent results indicate that thermal treatments in controlled atmosphere of gold + copper double-implanted silica favor the formation of either alloy nanoclusters or copper compounds, depending on the annealing atmosphere

  15. Uniform upconversion in high-concentration Er3+-doped soda lime silicate and aluminosilicate glasses

    International Nuclear Information System (INIS)

    Uniform upconversion in erbium-doped silicate glasses is investigated as a function of glass composition, concentration, and fabrication method. Comparisons of upconversion coefficients are made among soda lime silicate and aluminosilicate bulk glasses and soda lime silicate waveguides. Comparisons are also made with studies performed by other researchers. The results indicate that both the composition and the preparation method of the glass affect the value of the upconversion coefficient, with as much as a factor-of-4 variation observed at fixed Er3+ concentration. Values of the upconversion coefficient are found to be consistent with the Foerster endash Dexter microscopic model. copyright 1997 Optical Society of America

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

    Science.gov (United States)

    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.

  17. Modifier cation effects on (29)Si nuclear shielding anisotropies in silicate glasses.

    Science.gov (United States)

    Baltisberger, Jay H; Florian, Pierre; Keeler, Eric G; Phyo, Pyae A; Sanders, Kevin J; Grandinetti, Philip J

    2016-07-01

    We have examined variations in the (29)Si nuclear shielding tensor parameters of SiO4 tetrahedra in a series of seven alkali and alkaline earth silicate glass compositions, Cs2O·4.81 SiO2, Rb2O·3.96 SiO2, Rb2O·2.25 SiO2, K2O·4.48 SiO2, Na2O·4.74 SiO2, BaO·2.64 SiO2, and SrO·2.36 SiO2, using natural abundance (29)Si two-dimensional magic-angle flipping (MAF) experiments. Our analyses of these 2D spectra reveal a linear dependence of the (29)Si nuclear shielding anisotropy of Q((3)) sites on the Si-non-bridging oxygen bond length, which in turn depends on the cation potential and coordination of modifier cations to the non-bridging oxygen. We also demonstrate how a combination of Cu(2+) as a paramagnetic dopant combined with echo train acquisition can reduce the total experiment time of (29)Si 2D NMR measurements by two orders of magnitude, enabling higher throughput 2D NMR studies of glass structure. PMID:27187210

  18. Modifier cation effects on 29Si nuclear shielding anisotropies in silicate glasses

    Science.gov (United States)

    Baltisberger, Jay H.; Florian, Pierre; Keeler, Eric G.; Phyo, Pyae A.; Sanders, Kevin J.; Grandinetti, Philip J.

    2016-07-01

    We have examined variations in the 29Si nuclear shielding tensor parameters of SiO4 tetrahedra in a series of seven alkali and alkaline earth silicate glass compositions, Cs2O · 4.81 SiO2, Rb2O · 3.96 SiO2, Rb2O · 2.25 SiO2, K2O · 4.48 SiO2, Na2O · 4.74 SiO2, BaO · 2.64 SiO2, and SrO · 2.36 SiO2, using natural abundance 29Si two-dimensional magic-angle flipping (MAF) experiments. Our analyses of these 2D spectra reveal a linear dependence of the 29Si nuclear shielding anisotropy of Q(3) sites on the Si-non-bridging oxygen bond length, which in turn depends on the cation potential and coordination of modifier cations to the non-bridging oxygen. We also demonstrate how a combination of Cu2+ as a paramagnetic dopant combined with echo train acquisition can reduce the total experiment time of 29Si 2D NMR measurements by two orders of magnitude, enabling higher throughput 2D NMR studies of glass structure.

  19. Viscosity and thermal expansion of rare earth containing soda-lime-silicate glass

    International Nuclear Information System (INIS)

    Viscosity, coefficient of thermal expansion, glass transition temperature and dilatometric softening temperature of soda-lime-silicate glass doped with rare earth oxides (La2O3, CeO2, Nd2O3) were investigated by the rotating crucible viscometer and dilatometry, the melting temperature and activation energy for viscous flow of the studied melt were derived on the basis of Arrhenius equation, in order to reveal the effects of rare earth elements on the behavior of soda-lime-silicate glass. The results show that introduction of rare earth oxides increases the coefficient of thermal expansion, decreases viscosity of soda-lime-silicate glass, and Nd2O3 is an exception in viscosity. The glass transition temperature, dilatometric softening temperature, melting temperature and activation energy for viscous flow of soda-lime-silicate glass doped with rare earth oxides increase with increasing cationic field strength of corresponding rare earth ions.

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

    International Nuclear Information System (INIS)

    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-CO2 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 (C3S), blended C3S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C3S 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

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

    Science.gov (United States)

    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.

  2. Crystallisation mechanism of a multicomponent lithium alumino-silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Wurth, R. [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany); Pascual, M.J., E-mail: mpascual@icv.csic.es [Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Mather, G.C.; Pablos-Martin, A.; Munoz, F.; Duran, A. [Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Cuello, G.J. [Institut Laue-Langevin, Boite Postale 156, 38042 Grenoble Cedex 9 (France); Ruessel, C. [Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)

    2012-06-15

    A base glass of composition 3.5 Li{sub 2}O Bullet-Operator 0.15 Na{sub 2}O Bullet-Operator 0.2 K{sub 2}O Bullet-Operator 1.15 MgO Bullet-Operator 0.8 BaO Bullet-Operator 1.5 ZnO Bullet-Operator 20 Al{sub 2}O{sub 3} Bullet-Operator 67.2 SiO{sub 2} Bullet-Operator 2.6 TiO{sub 2} Bullet-Operator 1.7 ZrO{sub 2} Bullet-Operator 1.2 As{sub 2}O{sub 3} (in wt.%), melted and provided by SCHOTT AG (Mainz), was used to study the crystallisation mechanism of lithium alumino-silicate glass employing X-ray diffraction combined with neutron diffraction and non-isothermal differential scanning calorimetry (DSC). A high-quartz solid solution of LiAlSi{sub 2}O{sub 6} with nanoscaled crystals forms at 750 Degree-Sign C. Quantitative Rietveld refinement of samples annealed at 750 Degree-Sign C for 8 h determined a crystallised fraction of around 59 wt.%. The room temperature crystallised phase adopts an ordered, {beta}-eucryptite-like structure (2 Multiplication-Sign 2 Multiplication-Sign 2 cell) with Li ordered in the structural channels. The Avrami parameter (n {approx} 4), calculated from DSC data using different theoretical approaches, indicates that bulk crystallisation occurs and that the number of nuclei increases during annealing. The activation energy of the crystallisation is 531 {+-} 20 kJ mol{sup -1}. - Highlights: Black-Right-Pointing-Pointer Nanoscaled high-quartz crystals from a multicomponent lithium alumino-silicate glass. Black-Right-Pointing-Pointer Combined X-ray and neutron diffraction structural refinement. Black-Right-Pointing-Pointer {beta}-Eucryptite-like structure (2 Multiplication-Sign 2 Multiplication-Sign 2 cell) with Li ordered in the structural channels. Black-Right-Pointing-Pointer 3-Dimensional bulk crystallisation mechanism with an increasing number of nuclei. Black-Right-Pointing-Pointer Usage and validation of an alternative approach to calculate the Avrami parameter.

  3. Sensitivity of Structural Results to Initial Configurations and Quench Algorithms of Lead Silicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Hemesath, Eric R.; Corrales, Louis R.

    2005-06-15

    The sensitivity of resulting structures to starting configurations and quench algorithms were characterized using molecular dynamics (MD) simulations. The classical potential model introduced by Damodaran, Rao, and Rao (DRR) Phys. Chem. Glasses 31, 212 (1990) for lead silicate glass was used. Glasses were prepared using five distinct initial configurations and four glass forming algorithms. In previous MD work of bulk lead silicate glasses the ability of this potential model to provide good structural results were established by comparing to experimental results. Here the sensitivity of the results to the simulation methodology and the persistence of clustering with attention to details of molecular structure are determined.

  4. Photoelectron, nuclear gamma-ray and infrared absorption spectroscopic studies of neptunium in sodium silicate glass

    International Nuclear Information System (INIS)

    The valence state of neptunium ions in sodium silicate glasses prepared under reducing and oxidizing conditions has been investigated by the x-ray photoelectron, Moessbauer and optical absorption spectroscopic techniques. Results indicate that the Np ions are tetravalent in glasses prepared under reducing conditions and pentavalent in glasses prepared under oxidizing conditions

  5. 二元碱金属硅酸盐玻璃团簇结构的拉曼散射活性及其阳离子效应%Raman Spectroscopic Quantitative Analysis of Cluster Structure of Binary Alkali Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    王志超; 尤静林; 王媛媛; 牛玉静; 戴苏娟

    2011-01-01

    提出一种拉曼光谱校正方法.通过计算二元碱会属硅酸盐团簇基元的拉曼光谱,对实验光谱高频区的非桥氧(Onb)对称伸缩振动的强度进行了校正,从而建立谱峰强度和团簇实际浓度的直观相关关系,同时,分析研究了二元碱金属硅酸盐玻璃阳离子对谱峰强度的影响.校正后的拉曼光谱可以真实地显示同化学成分的二元碱金属硅酸盐玻璃表观实验拉曼谱峰强度随着阳离子的不同而变化.在环境和实验条件一致的情况下,这种强度的差异显然是由阳离子的不同所引起的.%A calibration method for Raman spectroscopic quantitative analysis of binary alkaline silicate glasses is proposed. By applying ab initio quantum chemistry simulation, Raman optical activities (ROA) of various cluster units consisting of siliconoxygen tetrahedra (SiOT) with different number of non-bridging oxygen (NBO) can be obtained, Thus, experimental results could be calibrated in order to reflect and represent directly the true relative density of various silicon-oxygen tetrahedra existing inside the silicate glasses. Cation effect on the intensity of Raman bands was also observed and discussed.

  6. Optical absorption and fluorescent behaviour of titanium ions in silicate glasses

    Indian Academy of Sciences (India)

    Manoj Kumar; Aman Uniyal; A P S Chauhan; S P Singh

    2003-04-01

    Titanium in normal melting conditions in air atmosphere present as Ti4+ ion in basic silicate glasses exhibited an ultra-violet cut-off in silicate glasses, viz. soda–magnesia–silica, soda–magnesia–lime–silica and soda–lime–silica glasses. This indicates that Ti4+ ion can be a good replacement for Ce4+ ion in producing UV-absorbing silicate glasses for commercial applications. The wavelength maxima at which the infinite absorption takes place in glasses was found to be around 310 nm against Ti-free blank glass in UV-region. The mechanism of electronic transition from O2- ligands to Ti4+ ion was suggested as L $\\rightarrow$ M charge transfer. The low energy tails of the ultra-violet cut-off were found to obey Urbach’s rule in the optical range 360–500 nm. The fluorescence spectra of these glasses were also studied and based on the radiative fluorescent properties it was suggested that the soda–lime–silica glass containing Ti4+ ion with greater emission crosssection would emit a better fluorescence than the corresponding soda–magnesia–lime–silica and soda–magnesia–silica glasses. The shift of emission wavelengths maxima towards longer wavelength in titania introduced silicate glasses was observed on replacement of MgO by CaO which may be attributed due to an increase in basicity of the glass system.

  7. The role of residual cracks on alkali silica reactivity of recycled glass aggregates

    DEFF Research Database (Denmark)

    Maraghechi, Hamed; Shafaatian, Seyed-Mohammad-Hadi; Fischer, Gregor;

    2012-01-01

    Despite its environmental and economical advantages, crushed recycled glass has limited application as concrete aggregates due to its deleterious alkali-silica reaction. To offer feasible mitigation strategies, the mechanism of ASR should be well understood. Recent research showed that unlike some...... natural aggregates, soda-lime glass undergoes ASR within cracks in the interior of glass particles and not at glass–paste interface. These cracks originate during bottle crushing and propagate further by ASR. This paper examines whether glass aggregates could become innocuous if these cracks are healed...... percentages of reactive microcracks which may explain why ASR expansions are lowered by reducing the size of glass aggregates....

  8. Conductivity studies of lithium zinc silicate glasses with varying lithium contents

    Indian Academy of Sciences (India)

    S K Deshpande; V K Shrikhande; M S Jogad; P S Goyal; G P Kothiyal

    2007-10-01

    The electrical conductivity of lithium zinc silicate (LZS) glasses with composition, (SiO2)0.527 (Na2O)0.054(B2O3)0.05(P2O5)0.029(ZnO)0.34–(Li2O) ( = 0.05, 0.08, 0.11, 0.18, 0.21, 0.24 and 0.27), was studied as a function of frequency in the range 100 Hz–15 MHz, over a temperature range from 546–637 K. The a.c. conductivity is found to obey Jonscher’s relation. The d.c. conductivity ($\\sigma_{d.c.}$) and the hopping frequency($\\omega_{h}$), inferred from the a.c. conductivity data, exhibit Arrhenius-type behaviour with temperature. The electrical modulus spectra show a single peak, indicating a single electrical relaxation time, , which also exhibits Arrhenius-type behaviour. Values of activation energy derived from $\\sigma_{d.c.}, \\omega_{h}$ and are almost equal within the experimental error. It is seen that $\\sigma_{d.c.}$ and $\\omega_{h}$ increase systematically with Li2O content up to 21 mol% and then decrease for higher Li2O content, indicating a mixed alkali effect caused by mobile Li+ and Na+ ions. The scaling behaviour of the modulus suggests that the relaxation process is independent of temperature but depends upon Li+ concentration.

  9. XRF analysis of major and trace elements for silicate rocks using low dilution ratio fused glass

    OpenAIRE

    Tanaka, Ryoji; ORIHASHI, Yuji

    1997-01-01

    An X-ray fluorescence spectrometry (XRF) method to determine 10 major and 18 trace elements in silicate rocks has been investigated. The analysis is carried out on fused glass beads, containing one part rock powder, two parts of lithium metaborate/tetraborate flux and 0.3 parts of lithium n itrate by weight. Calibration lines were established using international silicate rock reference materials. The low dilution fused glass technique effectively eliminates particle size effect...

  10. Influence of curing conditions on durability of alkali-resistant glass fibres in cement matrix

    Indian Academy of Sciences (India)

    Arabi Nourredine

    2011-07-01

    Glass fibres in concrete material often increase the flexural strength. However, these fibres when in contact with cement are altered by alkali reactions due to the presence of portlandite. This study presents the results of investigation to show the effect of curing conditions on the durability of alkali-resistant glass fibres in cement matrix. Test results show that even alkali resistant fibres treated with zirconium oxide present the same degradation phenomenon. They also show that the nature of the cement has a large influence on the protection of the fibres: the Portland CEM II is less damaging than the CEM I. The substitutions of a part of cement by silica fume gave no substantial improvements to the mechanical strength of the glass fibre reinforced cement (GFRC). However, the observed microstructures in the samples show that the degradation is weakened with the addition of silica fumes. The analytical techniques used in this study are scanning electron microscope (SEM) and X-ray diffraction.

  11. Alkali ion migration between stacked glass plates by corona discharge treatment

    Science.gov (United States)

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

    2015-05-01

    Corona discharge reflects the spatial migration of alkali ions over a gap between two glass plates. This study examined stacked glass plates containing different alkali ions treated with the corona discharge plasma generated by applied voltage of 4.5 kV at 200 °C. Protons generated at the anode electrode penetrate into the potassium-ion-containing upper glass plate, which is located 5 mm below the anode electrode. Potassium ions intruded into the lower glass plate containing sodium ions placed on the cathode electrode, even over a 1 mm gap separating the plates. Finally, the sodium ion discharged on the cathode electrode. The hydrogen atmosphere was effective at inhibiting the potassium ion reaction with ambient gases during the spatial migration between the two glass plates.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. Eu-, Tb-, and Dy-Doped Oxyfluoride Silicate Glasses for LED Applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Wang, J.; Zhang, M.M.;

    2014-01-01

    , and red-light wavelengths from Tb, Dy, and Eu ions. The optical performances can be tuned by varying the glass composition and excitation wavelength. Furthermore, we observed a remarkable emission spectral change for the Tb3+ single-doped oxyfluoride silicate glasses. The 5D3 emission of Tb3+ can......Luminescence glass is a potential candidate for the light-emitting diodes (LEDs) applications. Here, we study the structural and optical properties of the Eu-, Tb-, and Dy-doped oxyfluoride silicate glasses for LEDs by means of X-ray diffraction, photoluminescence spectra, Commission Internationale...... de L’Eclairage (CIE) chromaticity coordinates, and correlated color temperatures (CCTs). The results show that the white light emission can be achieved in Eu/Tb/Dy codoped oxyfluoride silicate glasses under excitation by near-ultraviolet light due to the simultaneous generation of blue, green, yellow...

  14. X-ray fluorescence analysis with micro glass beads using milligram-scale siliceous samples for archeology and geochemistry

    Science.gov (United States)

    Ichikawa, Shintaro; Nakamura, Toshihiro

    2014-06-01

    A micro glass bead technique was developed to assay precious siliceous samples for geochemical and archeological analyses. The micro-sized (approximately 3.5 mm in diameter and 0.8 mm in height) glass beads were prepared by mixing and fusing 1.1 mg of the powdered sample and 11.0 mg of the alkali lithium tetraborate flux for wavelength-dispersive X-ray fluorescence determination of major oxides (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, and total Fe2O3). The preparation parameters, including temperature and agitation during the fusing process, were optimized for the use of a commercial platinum crucible rather than a custom-made crucible. The procedure allows preparation of minute sample amounts of siliceous samples using conventional fusing equipment. Synthetic calibration standards were prepared by compounding chemical reagents such as oxides, carbonates, and diphosphates. Calibration curves showed good linearity with r values > 0.997, and the lower limits of detection were in the 10s to 100s of μg g- 1 range (e.g., 140 μg g- 1 for Na2O, 31 μg g- 1 for Al2O3, and 8.9 μg g- 1 for MnO). Using the present method, we determined ten major oxides in igneous rocks, stream sediments, ancient potteries, and obsidian. This was applicable to siliceous samples with various compositions, because of the excellent agreement between the analytical and recommended values of six geochemical references. This minimal-scale analysis may be available for precious and limited siliceous samples (e.g., rock, sand, soil, sediment, clay, and archeological ceramics) in many fields such as archeology and geochemistry.

  15. Structure and properties of soda lime silicate glass doped with rare earth

    International Nuclear Information System (INIS)

    Soda-lime-silicate glasses doped with different rare-earth oxides (La2O3, CeO2, Nd2O3, Gd2O3 and Y2O3) of 1 mol% content were prepared with the traditional melting-quenching methods. In order to reveal the effects of rare-earth elements on the behavior of soda-lime-silicate glass, the structure of soda-lime-silicate glasses doped with different rare-earth oxides were determined with Fourier transform infrared spectrometer using the KBr method, and viscosity of glass melts were measured by the rotating crucible viscometer, the melting temperature of the studied glasses were derived on the basis of Arrhenius Equation, moreover the density, bending strength and molar volume were measured and calculated. The effect of rare-earth dopants on the structure of soda-lime-silicate was analyzed by a shift of peak position and variation in the full-width at half-maximum. The effect of doping rare-earth oxides into glass on the viscosity, density and bending strength was interpreted by changing in structure of soda-lime-silicate glasses doped with rare-earth oxides.

  16. The Mixed-Alkali Effect on The Resistance of Glass to Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the composition of float glass, the resistance of glass to water, in which a small amount of K2O (0—1.0 wt%) was substituted for equivalent amount of Na2O, was investigated by means of glass grains testing. The components extracted from the glass and total alkalinities in extraction solution were determined by atomic absorption spectroscopy and neutralizing method, respectively. The composition of the glass was 14.4 K2O+Na2O, 4.0MgO, 8.2CaO, 1.4Al2O3, 72.0 SiO2, and the minimum extraction ratio of oxides (maximum durability) occurred at a K2O/Na2O ratio of 0.051(by weight) due to the presence of the mixed-alkali effect. The relative extraction ratio of alkali oxides (R2O) was greater than that of alkaline earth oxides (RO). By means of mixed-alkali effect and lowing relative contents of R2O in the glass, the resistance of float glass to water was improved and its mildew-proof ability was therefore increased.

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

    International Nuclear Information System (INIS)

    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 Li2O-K2O-ZnO-B2O3 doped with Fe3+ and Mn2+ were carried out at room temperature. The EPR spectra show typical resonances of d5 system (Fe3+ and Mn2+) 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.

  18. Influence of CeO_2 on scintillating properties of Tb~(3+)-doped silicate glasses

    Institute of Scientific and Technical Information of China (English)

    孙心瑗; 顾牡; 张敏; 黄世明

    2010-01-01

    A series of Tb3+-,Ce3+-doped,and Tb3+/Ce3+-codoped silicate glasses were synthesized by melt-quenching technique.Some properties of the investigated glasses were characterized by X-ray photoelectron spectroscopy(XPS),photoluminescence(PL),X-ray excited luminescence(XEL) and thermoluminescence(TL) spectra.The result of XPS revealed that both Ce3+ and Ce4+ ions coexisted in these silicate glasses,and energy transfer from Ce3+ to Tb3+ ions was observed under UV excitation.However,under X-ray excitation the XEL...

  19. Structure and topology of soda-lime silicate glasses: implications for window glass.

    Science.gov (United States)

    Laurent, O; Mantisi, B; Micoulaut, M

    2014-11-01

    The structural and topological properties of soda-lime silicate glasses of the form (1-2x)SiO2-xNa2O-xCaO are studied from classical molecular dynamics using a Buckingham type potential. Focus is made on three compositions (x = 6%, 12%, and 18%) which are either silica-rich or modifier-rich. We compare the results to available experimental measurements on structural properties and find that the simulated pair correlation function and total structure factor agree very well with available experimental measurements from neutron diffraction. The detail of the structural analysis shows that the Na and Ca coordination numbers tend to evolve with composition, and with increasing modifier content, changing from 5.0 to 5.6 and from 4.0 to 5.0 for Ca and Na, respectively. The analysis from topological constraints shows that the picture derived on a heuristic basis using classical valence rules remains partially valid. Ultimately, typical elastic phases are identified from the application of rigidity theory, and results indicate that the 6% system is stressed-rigid, whereas the modifier-rich composition (18%) is flexible. These results receive support from a full analysis of the vibrational density of states showing the low-energy bands at E glass. Consequences for window glass are discussed under this perspective. PMID:25295377

  20. Electrical conduction in alkali borate glasses; a unique dependence on the concentration of modifier ions

    Energy Technology Data Exchange (ETDEWEB)

    Doweidar, H; Moustafa, Y M; El-Damrawi, G M; Ramadan, R M [Glass Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura 35516, POB 83 (Egypt)

    2008-01-23

    The electrical conduction of Li{sub 2}O-B{sub 2}O{sub 3}, Na{sub 2}O-B{sub 2}O{sub 3} and K{sub 2}O-B{sub 2}O{sub 3} glasses seems, at first sight, to be dominated by the activation energy. Regardless of the size of the alkali ion, there is a unique dependence of conductivity, at a certain temperature, on the alkali-alkali distance and thus on N (the number of ions per cm{sup 3}). The linear dependence of log{sigma} on N{sup -3/2} for all types of alkali ions reveals that N is the basic parameter that determines the conductivity at a certain temperature. A derived semi-empirical relation can be used to calculate the conductivity as a function of N and temperature.

  1. Electrical conduction in alkali borate glasses; a unique dependence on the concentration of modifier ions

    Science.gov (United States)

    Doweidar, H.; Moustafa, Y. M.; El-Damrawi, G. M.; Ramadan, R. M.

    2008-01-01

    The electrical conduction of Li2O-B2O3, Na2O-B2O3 and K2O-B2O3 glasses seems, at first sight, to be dominated by the activation energy. Regardless of the size of the alkali ion, there is a unique dependence of conductivity, at a certain temperature, on the alkali-alkali distance and thus on N (the number of ions per cm3). The linear dependence of logσ on N-3/2 for all types of alkali ions reveals that N is the basic parameter that determines the conductivity at a certain temperature. A derived semi-empirical relation can be used to calculate the conductivity as a function of N and temperature.

  2. OBTAINMENT AND PHYSICO-MECHANICAL PROPERTIES OF THE FOAMED HEAT-INSULATING MATERIAL BASED ON ALKALI SILICATE COMPOSITION AND SHUNGITE

    Directory of Open Access Journals (Sweden)

    V. A. Lomonosov

    2015-01-01

    Full Text Available Physical and mechanical properties of foamed heat-insulating material based on alkali silicate composition and shungite were investigated. The studies determined the ratio of the components of the charge with which it is possible to obtain the optimal ratio of mechanical properties/thermal conductivity. Found that composite materials obtained from shungite filler, have a more porous structure (up to 76% of the volume of the material and are more uniform distribution of pore size (from 0.11 to 0.2 mm

  3. Alkali ion migration between stacked glass plates by corona discharge treatment

    International Nuclear Information System (INIS)

    Highlights: • Two stacked glass plates with a 1 mm gap were treated by corona discharge. • Spatial migration of alkali ion over the gap was demonstrated. • Hydrogen gas was necessary for uniform migration. • Surface modification was done with this process without high temperature or vacuum. - Abstract: Corona discharge reflects the spatial migration of alkali ions over a gap between two glass plates. This study examined stacked glass plates containing different alkali ions treated with the corona discharge plasma generated by applied voltage of 4.5 kV at 200 °C. Protons generated at the anode electrode penetrate into the potassium-ion-containing upper glass plate, which is located 5 mm below the anode electrode. Potassium ions intruded into the lower glass plate containing sodium ions placed on the cathode electrode, even over a 1 mm gap separating the plates. Finally, the sodium ion discharged on the cathode electrode. The hydrogen atmosphere was effective at inhibiting the potassium ion reaction with ambient gases during the spatial migration between the two glass plates

  4. Alkali ion migration between stacked glass plates by corona discharge treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Keiga [Research Institute for Electronic Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Hokkaido 001-0020 (Japan); Suzuki, Toshio [Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama, Kanagawa 221-8755 (Japan); Ikeda, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Sakai, Daisuke [Department of Electrical and Electronic Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan); Funatsu, Shiro; Uraji, Keiichiro [Production Technology Center, Asahi Glass Co., Ltd., 1-1 Suehiro-cyo, Tsurumiku, Yokohama, Kanagawa 230-0045 (Japan); Yamamoto, Kiyoshi [Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama, Kanagawa 221-8755 (Japan); Harada, Kenji [Department of Computer Science, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan); Nishii, Junji, E-mail: nishii@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Hokkaido 001-0020 (Japan)

    2015-05-30

    Highlights: • Two stacked glass plates with a 1 mm gap were treated by corona discharge. • Spatial migration of alkali ion over the gap was demonstrated. • Hydrogen gas was necessary for uniform migration. • Surface modification was done with this process without high temperature or vacuum. - Abstract: Corona discharge reflects the spatial migration of alkali ions over a gap between two glass plates. This study examined stacked glass plates containing different alkali ions treated with the corona discharge plasma generated by applied voltage of 4.5 kV at 200 °C. Protons generated at the anode electrode penetrate into the potassium-ion-containing upper glass plate, which is located 5 mm below the anode electrode. Potassium ions intruded into the lower glass plate containing sodium ions placed on the cathode electrode, even over a 1 mm gap separating the plates. Finally, the sodium ion discharged on the cathode electrode. The hydrogen atmosphere was effective at inhibiting the potassium ion reaction with ambient gases during the spatial migration between the two glass plates.

  5. Removal of lead from cathode ray tube funnel glass by generating the sodium silicate.

    Science.gov (United States)

    Hu, Biao; Zhao, Shuangshuang; Zhang, Shuhao

    2015-01-01

    In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na ₂CO₃to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass.

  6. Viscosity and Softening Behavior of Alkali Zinc Sulfophosphate Glasses

    DEFF Research Database (Denmark)

    Da, Ning; Krolikowski, Sebastian; Nielsen, Karsten Hansgaard;

    2010-01-01

    We report on the softening properties and viscosity of glasses from the system ZnO-Na2O-SO3-P2O5 for low-temperature sealing applications. Up to a ratio of network-forming ions PO(4)3-:SO(4)2- of about 2:1, a gradual substitution of P2O5 by SO3 results in decreasing glass transition and softening...

  7. Indentation recovery of soda-lime silicate glasses containing titania, zirconia and hafnia at low temperatures

    International Nuclear Information System (INIS)

    Highlights: ► The addition of titania, zirconia and hafnia in soda-lime silicate glass increases density, elastic moduli, Vickers hardness and brittleness. ► The effect of titania, zirconia and hafnia on the indentation recovery of soda-lime silicate glass is studied at 25 °C and 100 °C. ► The highest indentation recovery rate of glasses is observed within the first 6 h. ► The indentation recovery rate of glasses decreases with the increase in the size of tetravalent metal cations added. ► All the indentations exhibit three common features: elasticity, viscoelasticity and plasticity. - Abstract: From thermal treatment of indentations made on glass, the densification contribution to the total indentation deformation can be estimated. In this work, we studied the physico-mechanical properties and low-temperature indentation recovery of soda-lime silicate glasses with the composition of (in wt%) 73SiO2–12CaO–15Na2O–xTiO2 (ZrO2 or HfO2), where x is 0, 1, 2, 4 and 8. The obtained results demonstrated that the addition of group IV B metal oxides (TiO2, ZrO2 and HfO2) into soda-lime silicate glass increased density, elastic moduli, Vickers hardness and brittleness due to the higher atomic weight of additives, increased network connectivity, higher strength of individual bonds formed and lower molar volume, respectively. Indentation recovery of glass samples containing 8 wt% TiO2 (G5), 8 wt% ZrO2 (G9) and 8 wt% HfO2 (G13) was comparatively estimated with that of a pure soda-lime silicate glass (G1), as a reference, on the basis of the depth change of indentation impressions at low temperatures, 25 °C and 100 °C, for different periods with a maximum of 48 h. It was found that the higher indentation recovery for all four samples was observed at both temperatures within the first 6 h due to stored strain energy in deformation zone but equilibrium was not reached even after 48 h because of low thermal treatment temperatures, which generally provide a

  8. TEM studies of silver nanoparticles in phase-separated soda lime silicate glasses

    International Nuclear Information System (INIS)

    Transmission electron microscopy (TEM) was used to characterise the microstructure of a phase-separated soda lime silicate glass in which sodium was partially substituted by silver during the ion exchange process. To transform the dopant ions into nanosized particles of colloidal silver, high-temperature annealing (in air and hydrogen) and irradiation (γ-rays from a 60Co source) were used. It has been stated that both treatments affect not only the dopant ions but also the morphology of the matrix. A variety of the induced changes could be exploited for new applications of multicomponent soda lime silicate glasses

  9. Preparation and properties of silicate glasses containing CdSexTe1-x nanoparticles

    International Nuclear Information System (INIS)

    One analyzed conditions of CdSexTe1-x (0≤x≤1) ultradispersion particles in silicate glass. It is shown that when CdTe, CdSe compounds and CdSexTe1-x solid solutions are added to glass blend in finely dispersed state semiconducting phase is formed within matrix during glass making and is identified upon melt cooling down to the room temperatures in the form of nanoparticles. Peculiarities of absorption spectra of glasses are dictated by composition and concentration of nanoparticles of semiconducting phase and their crystalline structure

  10. Numerical Simulation of Soda-Lime Silicate Glass Tempering

    OpenAIRE

    Carre, H.; Daudeville, L.

    1996-01-01

    The paper deals with the computation of residual and transient stresses in a tempered glass plate. The modelling takes into account the viscoelastic behavior and the structural relaxation of glass. The evolution of stresses with time during the rapid cooling is computed. Simulation results are compared with experimental ones from the literature available. Levels of transient tensile stress in the surface are analysed.

  11. Spectroscopic Properties and Judd-Ofelt Theory Analysis of Er3+-Doped Heavy Metal Oxyfluoride Silicate Glass

    Institute of Scientific and Technical Information of China (English)

    徐时清; 杨中民; 戴世勋; 张军杰; 胡丽丽; 姜中宏

    2004-01-01

    Er3+-doped heavy metal oxyfluoride silicate glass was fabricated and characterized, and the absorption spectrum and fluorescence spectrum of the glass were studied. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6), spontaneous transition probability, fluorescence branching ratio and radiative lifetime of each energy levels for Er3+ were calculated by Judd-Ofelt theory, and stimulated emission cross-section of 4I13/2→4I15/2 transition was calculated by McCumber theory. The results show that fluorescence full width at half maximum and stimulated emission cross-section of Er3+-doped heavy metal oxyfluoride silicate glass are broad and large, respectively. Compared with other host glasses, the gain bandwidth property of Er3+-doped heavy metal oxyfluoride silicate glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses.

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

    Science.gov (United States)

    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.

  13. Silicate glass alteration enhanced by iron: origin and long-term implications

    International Nuclear Information System (INIS)

    Silicate glasses are used as containment matrices for deep geological disposal of nuclear waste arising from spent fuel reprocessing. Understanding the dissolution mechanisms of glasses in contact with iron, an element present in large amounts in the immediate environment (overpack, clay-stone, etc.) would be a major breakthrough toward predicting radionuclide release in the geosphere after disposal. Two different reacted glass-iron interfaces - a short-term nuclear system and a long-term archaeological system - were examined using a multi-scale and multi-analytical approach including, for the first time on samples of this type, STXM under synchrotron radiation. Comparisons revealed remarkable similarities between the two systems and shed light on Fe-Si interactions, including migration of iron within a porous gel layer and precipitation of Fe-silicates that locally increase short-term glass alteration and are sustainable over the long-term. (authors)

  14. Iron modified structural and optical spectral properties of bismuth silicate glasses

    International Nuclear Information System (INIS)

    Iron bismuth silicate glasses have been successfully synthesized by melt quenching technique. The amorphous nature of the glass samples is ascertained by the XRD patterns. The values of density, molar volume and crystalline volume have been measured and are found to decrease with increase in iron content. The glass transition temperature measured using Differential Scanning Calorimetry (DSC) also varies with increase in Fe2O3 content. The Raman and FTIR spectra of the studied glass system taken at room temperature suggests that Fe2O3 modifies the structure of bismuth silicate glasses and it acts as both network modifier as well as network former. Bismuth also plays the role of both network modifier (BiO6 octahedra) as well as network former (BiO3 pyramids) and SiO2 exists in SiO4 tetrahedral structural units with two non-bridging oxygens. The Hydrogenic excitonic model is found to be applicable to the studied glass compositions. The variation in Urbach energy value observed for the studied glass samples suggests the possibility of increase in the number of glass defects. The metallization criterion for the synthesized glass samples is determined and found to be in the range 0.30–0.38

  15. Dependence of Hardness of Silicate Glasses on Composition and Thermal History

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Yue, Yuanzheng

    a decrease in hardness. However, hardness cannot solely be determined from the degree of polymerisation of the glass network. It is also determined by the effect of ionic radius on hardness. However, this effect has opposite trend for alkali and alkaline earth ions. The hardness increases with ionic radius...... for the alkali series, whereas it decreases for the alkaline earth series. Hence, the field strength of modifiers, the packing density of modifiers, and other factors must be taken into account when predicting hardness from chemical composition. The principles used in the calculation of hardness of crystalline......The prediction of hardness is possible for crystalline materials, but so far not possible for glasses. In this work, several important factors that should be used for predicting the hardness of glasses are discussed. To do so, we have studied the influences of thermal history and chemical...

  16. Tin-containing silicates: Alkali salts improve methyl lactate yield from sugars

    DEFF Research Database (Denmark)

    Tolborg, Søren; Sádaba, Irantzu; Osmundsen, Christian Mårup;

    2015-01-01

    This study focuses on increasing the selectivity to methyl lactate from sugars using stannosilicates as heterogeneous catalyst. All group I ions are found to have a promoting effect on the resulting methyl lactate yield. Besides, the alkali ions can be added both during the preparation of the cat......This study focuses on increasing the selectivity to methyl lactate from sugars using stannosilicates as heterogeneous catalyst. All group I ions are found to have a promoting effect on the resulting methyl lactate yield. Besides, the alkali ions can be added both during the preparation...

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

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M. Sudhakara; Rajiv, Asha [Department of Physics, Jain University, Bangalore (India); Veeranna Gowda, V. C. [Department of Physics, GovernmentCollege for Women, Chintamani (India); Chakradhar, R. P. S. [CSIR-National Aerospace Laboratories, Bangalore (India); Reddy, C. Narayana [Department of Physics, Maharani' s Science College for Women (PG centre, Bangalore University) Bangalore (India)

    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.

  18. UV-laser-induced nanoclusters in silver ion-exchanged soda-lime silicate glass

    International Nuclear Information System (INIS)

    Excimer-laser irradiation (ArF: 193 nm) was performed on silver-exchanged commercial soda-lime silicate glass. Silver nanoclusters were obtained with an average size dependent on the irradiation time, without subsequent heating. Laser irradiation induces the reduction of silver ions and promotes the silver atoms aggregation

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

    DEFF Research Database (Denmark)

    Cheng, D.S.; Yang, G.; Zhao, Y.Q.;

    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...

  20. IR and Raman spectroscopic studies of sol–gel derived alkaline-earth silicate glasses

    Indian Academy of Sciences (India)

    Angelos G Kalampounias

    2011-04-01

    IR and Raman spectroscopies have been utilized to study the structure and vibrational modes of sol–gel-derived binary silicate glasses. The present study is motivated by the immense geological significance and focuses on the MO–SiO2 (M = Ca, Mg) binary systems in an effort to unveil the role of the CaO and MgO modifiers when incorporated to the 3D silica structure. Glasses in the composition range = 0, 0.1, 0.2, 0.3 and 0.4 prepared by the sol–gel method were compared with the corresponding glasses formed by appropriate mixing of SiO2 and MO powders through melting and fast cooling. The vibrational spectra of the sol–gel-derived glasses have revealed considerable changes in relative intensities as a function of the MO mole fraction. These changes signify structural modifications on the silica network. The population of the 3 species was found to increase for both modified silicate systems. The rate of increase is more pronounced in the CaO–SiO2 glasses. The extent of network depolymerization in the porous glass is higher at the same content of alkaline earth oxide compared to the bulk glass. The results are indicative of a more `defective’ nature of the sol–gel glasses compared to the corresponding melt-quenched ones.

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

    Science.gov (United States)

    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.

  2. Soda-lime silicate glass under hydrostatic pressure and indentation: a micro-Raman study

    International Nuclear Information System (INIS)

    Raman micro-spectroscopy is used to analyse the plastic behaviour of window glass (a soda-lime silicate glass) under high hydrostatic pressure and Vickers indentation. We show pressure-induced irreversible structural changes, notably an increase of Q2 species at the expense of Q3. For the first time, a very accurate Raman↔pressure calibration curve has been established. Local density variations of a Vickers indented window glass have been characterized by micro-Raman mapping using a high spatial resolution device. The effects of glass depolymerization on indentation and hydrostatic compression are discussed. Differences between window glass and pure SiO2 glass behaviour under high stresses are also highlighted and analysed at a local scale.

  3. X-ray photoemission spectroscopy (XPS) study uranium, neptunium, and plutonium oxides in silicate-based glasses

    International Nuclear Information System (INIS)

    Using XPS as the principal investigative tool, the bonding properties of selected metal oxides added to silicate glass are being examined. In this paper, the results of XPS studies of uranium, plutonium, and neptunium in binary and multicomponent silicate-based glasses are presented. Models are proposed to account for the very diverse bonding properties of 6+ and 4+ actinide ions in glass. 15 references, 3 figures, 1 table

  4. X-ray photoemission spectroscopy (XPS) study of uranium, neptunium and plutonium oxides in silicate-based glasses

    International Nuclear Information System (INIS)

    Using XPS as the principal investigative tool, we are in the process of examining the bonding properties of selected metal oxides added to silicate glass. In this paper, we present results of XPS studies of uranium, neptunium, and plutonium in binary and multicomponent silicate-based glasses. Models are proposed to account for the very diverse bonding properties of 6+ and 4+ actinide ions in the glasses

  5. Spectral Properties of Erbium-Doped Oxyfluoride Silicate Glasses for Broadband Optical Amplifiers

    Institute of Scientific and Technical Information of China (English)

    徐时清; 杨中民; 戴世勋; 杨建虎; 温磊; 胡丽丽; 姜中宏

    2003-01-01

    The new oxyfluoride silicate glasses of Er3+-doped 50SiO2-(50-x)PbO-xPbF2 were prepared. With increasing PbF2 content in the glass composition, the fluorescence full width at half maximum and lifetimes of the 4I13/2level of Er3+ increase, while the refractive indices and densities decrease. Er3+-doped 50SiO2-50PbF2 glass showed broad fluorescence spectra of 1.55μm with a large stimulated emission cross-section and long lifetimes of 4I13/2level of Er3+. Compared with other glass hosts, the gain bandwidth properties of Er3+-doped 50SiO2-50PbF2glass are close to those of tellurite and bismuth glasses, and have advantages over those of silicate, phosphate and germante glasses. The broad and flat 4I13/2 → 4I15/2 emission of Er3+ around 1.55μm can be used as host material for potential broadband optical amplifier in wavelength-division-multiplexing network system.

  6. Nonlinear dynamics and instability of aqueous dissolution of silicate glasses and minerals

    Science.gov (United States)

    Wang, Yifeng; Jove-Colon, Carlos F.; Kuhlman, Kristopher L.

    2016-07-01

    Aqueous dissolution of silicate glasses and minerals plays a critical role in global biogeochemical cycles and climate evolution. The reactivity of these materials is also important to numerous engineering applications including nuclear waste disposal. The dissolution process has long been considered to be controlled by a leached surface layer in which cations in the silicate framework are gradually leached out and replaced by protons from the solution. This view has recently been challenged by observations of extremely sharp corrosion fronts and oscillatory zonings in altered rims of the materials, suggesting that corrosion of these materials may proceed directly through congruent dissolution followed by secondary mineral precipitation. Here we show that complex silicate material dissolution behaviors can emerge from a simple positive feedback between dissolution-induced cation release and cation-enhanced dissolution kinetics. This self-accelerating mechanism enables a systematic prediction of the occurrence of sharp dissolution fronts (vs. leached surface layers), oscillatory dissolution behaviors and multiple stages of glass dissolution (in particular the alteration resumption at a late stage of a corrosion process). Our work provides a new perspective for predicting long-term silicate weathering rates in actual geochemical systems and developing durable silicate materials for various engineering applications.

  7. Glass Forming Ability of Sub-Alkaline Silicate Melts

    Science.gov (United States)

    Vetere, F. P.; Iezzi, G.; Behrens, H.; Holtz, F.; Ventura, G.; Misiti, V.; Mollo, S.; Perugini, D.

    2014-12-01

    The glass forming ability (GFA) and critical cooling rate (Rc) of six natural sub-alkaline melts from basalt to rhyolite (i.e., B100, B80R20, B60R40, B40R60, B20R80, and R100) have been quantified through cooling-induced solidification experiments of 9000, 1800, 180, 60, 7 and 1 °C/h conducted at ambient pressure and air buffering conditions, in a temperature range between 1300 °C (superliquidus region) and 800 °C (glass transition region), The phase proportion in each run-product was determined by image analysis on about 500 BS-SEM microphotographs. The phase assemblage consists of glass, clinopyroxene, spinel, and plagioclase with the occurrence of sporadic olivine, orthopyroxene and melilite. Both the glass and crystalline fractions are well correlated with the composition of residual melt. Generally, the amount of crystals decreases with increasing cooling rate. However, some exceptions occurs showing no correlations or even opposite trends. For the example of, Al2O3 and CaO in clinopyroxenes from B100, B80R20, B60R40 and B40R60, their concentrations scale as a function of both cooling rate and the degree of clinopyroxene crystallization. The value of Rc changes of 5 order of magnitude from retrieve the solidification conditions of aphyric, degassed and oxidised lavas. Indeed, the relationship between crystal content and cooling kinetics suggests that the solidification path is more complex than previously assumed and strongly non-linear. This finding has also implications to design glass-ceramics based on natural, accessible and low-cost starting materials.

  8. Barium silicate glass/Inconel X-750 interaction. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Kelsey, Jr., P. V.; Siegel, W. T.; Miley, D. V.

    1980-01-01

    Water reactor safety programs at the Idaho National Engineering Laboratory have required the development of specialized instrumentation. An example is the electrical conductivity-sensitive liquid level transducer developed for use in pressurized-water reactors (PWRs) in which the operation of the sensing probe relies upon the passage of current through the water between the center pin of the electrode and its shell such that when water is present the resulting voltage is low, and conversely, when water is absent the voltage is high. The transducer's ceramic seal is a hot-pressed glass ceramic; its metal housing is Inconel X-750. The ceramic material provides an essential dielectric barrier between the center pin and the outer housing. The operation of the probe as well as the integrity of the PWR environment requires a hermetically-bonded seal between the ceramic and the metal. However, during testing, an increasing number of probe assemblies failed owing to poor glass-to-metal seals as well as void formation within the ceramic. Therefore, a program was initiated to characterize the metallic surface with respect to pre-oxidation treatment and determine optimum conditions for wetting and bonding of the metal by the glass to obtain baseline data relevant to production of acceptable transducer seals.

  9. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  10. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    International Nuclear Information System (INIS)

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle–glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers’ hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H2/N2 atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle–glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required

  11. ER3+-DOPED SODA-LIME SILICATE GLASS: ARTIFICIAL PINK GEMSTONE

    Directory of Open Access Journals (Sweden)

    Weeranut Kaewwiset

    2012-01-01

    Full Text Available Er3+-doped soda-lime silicate glasses of the composition (in mol% (65-xSiO2:25Na2O:10CaO:xEr2O3 (where x = 0, 1, 2, 3, 4 and 5 were fabricated by conventional melt quenching technique. The physical and optical properties were measured and investigated. The erbium oxide enters the glass network as a modifier by occupying the interstitial space in the network and generating the NBOs to the structure. The molar volume increases with an increase in Er2O3 content, which is attributed to the increase in the number of Non-Bridging Oxygen (NBOs. The increase of NBOs in the structure generally leads to an increase in average atomic separation. The density, molar volume and refractive index of glasses increased linearly with increasing Er2O3 concentration. The color of glasses was changed from light pink to intense pink as the Er2O3 concentration was increased from 1 to 5 mol%. The Vickers hardness of Er3+-doped glasses was found to be in the range of 450-500 HV. In this study, it can be concluded that the soda-lime silicate glasses doped with high Er2O3 concentration has intense pink color and high value of hardness which is suitable to be cut as gems.

  12. Elaboration And Characterization Of Foam Glass Based On Cullet With Addition Of Soluble Silicates

    International Nuclear Information System (INIS)

    The politics of the energy saving and of the acoustic comfort buildings is at the heart of the research of new compounds permitting to improve the materials performance actually commercialised. With this aim in view, we'll purpose to elaborate a porous material (foam glass) with addition of soluble silicates (up to 40%) of which the principal material is the waste glass in order to recycle it and improving the present laws about the waste products in closed circuit: (Finished products (leftarrow) waste products(leftarrow) finished products). The investigations have shown that grinding waste glass to particle size less than 0.1 mm and adding 1% of Ca CO3 content provide production of material with the following properties: particle density 0,5 g/cm3, strength 17,50 MPa and water adsorption 95%, the temperature for foaming ranges were determined at 850 deg. C. The microstructures are homogenous, with pore sizes up to 2 mm. The addition of soluble silicates (up to 40%) has resulted in the foam glass of very high porosity. The foam glass is counted among the new glass products meeting certain requirements sought comfort in the building industry in particular (thermal and acoustic insulation). The product obtained present of excellent properties thermal (λ = 0,031 W/m deg. C) and acoustic (R = 15 dB).

  13. O-17 NMR studies of some silicate crystals and glasses

    CERN Document Server

    Yildirim, E K

    2000-01-01

    structure. Therefore some of the Sn has to be in three coordinated to oxygen for charge balancing. The sup 1 sup 7 O MAS NMR spectra of a partially crystallised sample showed three distinct sites which are assigned as Sn-O-Sn, Si-O-Sn, and Si-O-Si on the basis of their chemical shift. The C sub Q values obtained from the simulations of these peaks supports this assignment. The sup 2 sup 9 Si MAS NMR of the same sample showed two crystalline and a glassy peaks which are fitted to two crystalline and two glassy sites. The possible composition of this sample was calculated and found to be SiSn sub 8 O sub 1 sub 0. Crystalline and glassy silicates were investigated by means of sup 1 sup 7 O NMR. The dependence of the measured efg on the Si-O-AI bond angle was investigated in some crystalline aluminosilicate sodalites and kalsilite. The results show that C sub Q increases with increasing bond angle while eta decreases with increasing bond angle and they both follow a similar function to that found for the Si-O-Si ...

  14. The role of alkalis in the solubility of H2O and CO2in silicate melts

    Science.gov (United States)

    Vetere, F.; Behrens, H.; Botcharnikov, R. E.; Holtz, F.; Fanara, S.

    2013-12-01

    In order to investigate the role of alkalis on the behavior of H2O and CO2 in magmatic systems, the solubility of volatiles in phonotephritic melts was investigated experimentally and compared to other melt compositions. The investigated compositions have Na2O/K2O ratios (in wt %) of 0.26 (Ab1, natural phonotephrite from Alban Hills, Italy), 0.98 (Ab2) and 3.82 (Ab3). Experiments were run at 1250°C and 500 MPa in an internally heated gas pressure vessel. The mole fraction of water (XH2O) in the fluid phase composed of H2O and CO2 varied in the range from 0 to 1. For the calibration of carbon-related IR bands in glasses, the total carbon content of synthesized glass standards was measured by combustion and subsequent IR spectroscopy using an ELTRA CS800 analyzer. Karl Fischer Titration method was used to quantify the H2O content of the glasses. Absorption spectra were recorded in the mid-infrared (MIR) using a Bruker IFS88 FTIR spectrometer coupled with an IR-ScopeII microscope. CO2 is bounded in the investigated glasses as CO32- exclusively and its concentration was quantified by the peak height of the 1430 cm-1 band. A drastic change was observed in the absorption coefficients, ɛ, with values of 294 × 35, 329 × 40 and 244 × 23 L/(mol cm) , for Ab1, Ab2, and Ab3, respectively, so that the highest ɛ value is related to the Na-rich composition. There is no evident effect of the Na/K ratio on the concentrations of dissolved H2O and CO2 in the melts. The solubility of CO2 and H2O in those melts at 500 MPa is 0.95 wt % CO2 and 10.07 wt% H2O for XH2O of 0 and 1, respectively. Results are compared with the existing literature data and models and confirm the very high solubility of CO2 in phonotephritic melts [1]. Our experimental data indicate that the melt composition in terms of alkali contents influences significantly the extinction coefficient values for CO2 and that appropriate coefficients must be selected to estimate accurately the amount of dissolved CO2 in

  15. Optical properties and structure of beryllium lead silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhidkov, I. S., E-mail: i.s.zhidkov@urfu.ru [Ural Federal University, Mira Str. 19, Yekaterinburg, 620002, Russia and Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Str. 18, 620990 Yekaterinburg (Russian Federation); Zatsepin, A. F.; Cholakh, S. O.; Kuznetsova, Yu. A. [Ural Federal University, Mira Str. 19, Yekaterinburg, 620002 (Russian Federation)

    2014-10-21

    Luminescence and optical properties and structural features of (BeO){sub x}(PbO⋅SiO{sub 2}){sub 1−x} glasses (x = 0 ÷ 0.3) are investigated by means of optical absorption and photoluminescence spectroscopy and X-ray diffraction. The regularities of the formation of the optical absorption edge and static disorder are studied. It is shown that the optical absorption and luminescence are determined by transitions between localized states of lead ions. The impact of beryllium oxide on optical and luminescence properties and electronic structure of bands tails is discussed. The presence of two different concentration ranges with various short-range order structure and band tails nature has been established.

  16. Optical properties and structure of beryllium lead silicate glasses

    Science.gov (United States)

    Zhidkov, I. S.; Zatsepin, A. F.; Cholakh, S. O.; Kuznetsova, Yu. A.

    2014-10-01

    Luminescence and optical properties and structural features of (BeO)x(PbOṡSiO2)1-x glasses (x = 0 ÷ 0.3) are investigated by means of optical absorption and photoluminescence spectroscopy and X-ray diffraction. The regularities of the formation of the optical absorption edge and static disorder are studied. It is shown that the optical absorption and luminescence are determined by transitions between localized states of lead ions. The impact of beryllium oxide on optical and luminescence properties and electronic structure of bands tails is discussed. The presence of two different concentration ranges with various short-range order structure and band tails nature has been established.

  17. An intrinsic luminescence in binary lead silicate glasses

    Science.gov (United States)

    Zatsepin, А. F.; Zhidkov, I. S.; Kukharenko, A. I.; Zatsepin, D. А.; Andronov, М. P.; Cholakh, S. О.

    2012-03-01

    The low-temperature photoluminescence (PL) of xPbO · (1 - x)SiO2 glasses (x = 0.20-0.75) was studied at Т = 10 K. The recorded PL-spectra are a superposition of three spectral components with maxima located at 1.8 eV (identified as Pb 6p → metal-bridging O2p radiative electron transition, the "R"-band), 2.0 eV (Pb 6p → non-bridging O2p, the "O"-band) and 2.55 eV (Pb 6p → Pb 6s, the "B"-band), respectively. It was found the essential link for "R", "O" and "B" PL-bands with chemical composition x of the glasses under study. These concentration dependences are expressed as mutual PL-intensity variations for each recorded luminescence band that allowed to determine their origin. The shape of established dependences well coincides with numerical data on NBO- and MBO-density of chemical bonding, reported previously. The overall PL-manner within the temperature range of 10-295 K is described by an empirical Street's law. It was shown that experimental photoluminescence quenching curves may be precisely approximated as a superposition of Mott relationships for nonequivalent luminescence centers. The obtained distribution of PL-centers on the activation energy for luminescence quenching reflects the essential donation of the low-energy states into the overall PL-process. The width of this energy distribution affects by the type of PL-emission band and the disordering degree in the arrangement of local PL-centers of a certain kind.

  18. Evaluation of Spectroscopic Properties of Yb3+ in Silicate-Based Heavy Metal Oxide Glasses

    Institute of Scientific and Technical Information of China (English)

    戴能利; 胡丽丽; 戴世勋; 杨建虎; 林傲翔

    2003-01-01

    The absorption, stimulated emission cross section and potential laser parameters of heavy metal silicate glasses doped with Ybs+ ions have been investigated. The emission cross section has been evaluated by using the measured absorption spectra and principle of reciprocity. It is found that Yb3+ in SiO2-Bi2O3-B2O3 glass has high stimulated emission cross section of 0. Gpm2 for the 2F5/2 → 2F7/2 transition and exists short measured fluorescence lifetime of 0. 78 ms. On the other hand, the stimulated emission cross section of Yb3+-doped SiO2PbO glass was 0.49pm2. Its measured fluorescence lifetime was 2.00ms. Evaluated from the good potential laser parameters, Yb3+-doped SiO2-PbO glass may be a good candidate for fibre laser applications.

  19. Molecular dynamics simulations of silicate and borate glasses and melts : structure, diffusion dynamics and vibrational properties

    OpenAIRE

    Scherer, Christoph

    2015-01-01

    Molecular dynamics simulations of silicate and borate glasses and melts: Structure, diffusion dynamics and vibrational properties. In this work computer simulations of the model glass formers SiO2 and B2O3 are presented, using the techniques of classical molecular dynamics (MD) simulations and quantum mechanical calculations, based on density functional theory (DFT). The latter limits the system size to about 100−200 atoms. SiO2 and B2O3 are the two most important network formers for industri...

  20. Raman Mapping of the Indentation-Induced Densification of a Soda-Lime-Silicate Glass

    OpenAIRE

    Kassir-Bodon, Assia; Deschamps, Thierry; Martinet, Christine; Champagnon, Bernard; Teisseire, Jérémie; Kermouche, Guillaume

    2012-01-01

    Micro-Raman spectroscopy was used to map the Vickers indentation-induced densification on a window glass (soda-lime silicate glass), from the correlation between Raman spectrum and density. Both top surface and cross-section of the residual imprints were investigated. It is shown that the sample preparation needed for the investigation of the in-depth densification does not alter the results. The maximum densification ratio measured is about 3.8%, which is 60% of the maximum densification mea...

  1. ER3+-DOPED SODA-LIME SILICATE GLASS: ARTIFICIAL PINK GEMSTONE

    OpenAIRE

    Weeranut Kaewwiset; Kheamrutai Thamaphat; Jakrapong Kaewkhao; Pichet Limsuwan

    2012-01-01

    Er3+-doped soda-lime silicate glasses of the composition (in mol%) (65-x)SiO2:25Na2O:10CaO:xEr2O3 (where x = 0, 1, 2, 3, 4 and 5) were fabricated by conventional melt quenching technique. The physical and optical properties were measured and investigated. The erbium oxide enters the glass network as a modifier by occupying the interstitial space in the network and generating the NBOs to the structure. The molar volume increases with an increase in Er2O3 content, which is attributed to the inc...

  2. Nd3+ Doped Silicate Glass Photonic Crystal Fiber with Random Hole Distributions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The fabrication of one kind of large core area Nd3+ doped silicate glass photonic crystal fiber, and demonstration of the fiber's waveguidence properties were reported. This fiber owns a random air hole distribution in the cladding. The measured minimum loss of this kind of fiber is 10 dB·m-1 at 660 nm. These fibers can sustain only a single mode at least over wavelength ranging from 660 nm to 980 nm.

  3. Raman thresholds and rigid to floppy transitions in calcium silicate glasses

    OpenAIRE

    Micoulaut, M.; Malki, M.; Simon, P.; Canizares, A.

    2004-01-01

    Alkaline earth silicate glasses $xCaO-(1-x)SiO_2$ exhibit a well marked threshold in Raman lineshapes which can be related to the onset of network rigidity as the concentration of calcium oxide $x$ is decreased. The present results are analyzed by constraint counting algorithms and more deeply characterized by a size increasing cluster approximation that allows to perform Maxwell mechanical constraint counting beyond the usual mean-field treatment. This permits to discuss under which structur...

  4. Infrared emissivity spectroscopy of a soda-lime silicate glass up to the melt

    OpenAIRE

    Cristiane N. Santos; Meneses, Domingos de S.; Montouillout, Valérie; Echegut, Patrick

    2012-01-01

    The short-range structure of an iron doped soda-lime glass was investigated by infrared emissivity spectroscopy from room temperature up to the melt. Quantitative information on the distribution of the Q^n tetrahedral units was obtained by fitting the emissivity spectra using a dielectric function model (DFM). The DFM is based on causal Gaussian bands, associated with the stretching motions of the silicate tetrahedra. The changes in the absorption modes are related to the activation of a dyna...

  5. Velocity of a freely rising gas bubble in a soda-lime silicate glass melt

    Science.gov (United States)

    Hornyak, E. J.; Weinberg, M. C.

    1984-01-01

    A comparison is conducted between measured velocities for the buoyant rise of single bubbles of varying size and composition, in a soda-lime silicate glass melt, with the steady state velocities predicted by the Stokes and Hadamard-Rybczynski formulas. In all cases, the data are noted to fit the Hadamard-Rybczynski expression for steady state rise speed considerably better than the Stokes formula.

  6. Fading behavior of X-ray induced color centers in soda-lime silicate glass

    International Nuclear Information System (INIS)

    The X-ray induced color centers in soda-lime silicate glass were unstable at room temperature. There was a rapid fading at short-term stage and a slow fading at long-term stage. In the short-term stage, both first-order and second-order fading kinetics played roles in the fading process, while only the first-order fading controlled the long-term stage fading

  7. Annealing effect on the ultrafast dynamics of Ag nanoparticles embedded in soda-lime silicate glasses

    International Nuclear Information System (INIS)

    Ag nanoparticles embedded in soda-lime silicate glasses were fabricated by the ion-exchange technique. Effects of thermal treatment on the optical nonlinearity and ultrafast dynamics of Ag nanoparticles were investigated by applying time-resolved optical Kerr effect and pump-probe techniques. The results indicate that thermal treatment is an efficient method to improve the nonlinear optical performance of this kind of material.

  8. Optical studies in gamma-irradiated commercial soda-lime silicate glasses

    International Nuclear Information System (INIS)

    Optical absorption measurements of gamma-irradiated (60Co) commercial soda-lime silicate (SLS) glasses were performed at room temperature (RT) to detect and characterize the induced radiation damage in these materials. Isothermal bleaching (RT-723 K) of the radiation-induced defects, followed the irradiation of samples. In glasses containing different amount of the glass-network modifiers (Na2O, K2O) and some multivalent transition metal cations (Fe2+/Fe3+, Ni2+ and/or Mn2+) three absorption bands have been distinguished in the wavelength region extending from 250 to 1800 nm. In contrast to the electron-type color centers, detected at low temperatures for X-irradiated nominally pure sodium silicates , we propose that the absorption bands found for gamma-irradiated SLS glasses are induced by some hole-type color centers related with nonbridging oxygen ions (NBO-) located in different surroundings. The radiation-induced enhancement of diffusivity of ions together with bond breaking and defect creation in the glass-network could give materials with well-defined nonlinear optical properties

  9. Radiation induced color centers in cerium-doped and cerium-free multicomponent silicate glasses

    Institute of Scientific and Technical Information of China (English)

    傅鑫杰; 宋力昕; 李家成

    2014-01-01

    The effect of doped cerium on the radiation-resistance behavior of silicate glass was investigated in our work. The ultra-violet-visible absorption spectra and electron paramagnetic resonance (EPR) spectra were obtained after the cerium-rich and ce-rium-free multicomponent silicate glasses (K509 and K9) were irradiated by gamma rays with a dose range from 10 to 1000 kGy. The results showed that E’ center, oxygen deficient center (ODC) and non-bridging oxygen hole center (HC1 and HC2) were induced in K9 and K509 glasses after radiation. The concentrations of all color centers presented an exponential growth with the increase of the gamma dose. Moreover, the concentration of HC1 and HC2 in cerium-doped K509 glass was much lower than that in cerium-free K9 glass at the same dose of radiation, which could be attributed to the following mechanism:Ce3+ions capturing holes then forming Ce3++centers inhibited the formation of hole trapped color centers (HC1 and HC2) and Ce4+ions capturing electrons to form Ce3+centers suppressed the formation of electron trapped color centers like E’ center.

  10. Sub-critical crack growth in silicate glasses: Role of network topology

    Energy Technology Data Exchange (ETDEWEB)

    Smedskjaer, Morten M., E-mail: mos@bio.aau.dk [Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg (Denmark); Bauchy, Mathieu [Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095 (United States)

    2015-10-05

    The presence of water in the surrounding atmosphere can cause sub-critical crack growth (SCCG) in glasses, a phenomenon known as fatigue or stress corrosion. Here, to facilitate the compositional design of more fatigue-resistant glasses, we investigate the composition dependence of SCCG by studying fourteen silicate glasses. The fatigue curves (V-K{sub I}) have been obtained by indentation experiments through measurements of the crack length as a function of post-indentation fatigue duration. Interestingly, we find that the fatigue resistance parameter N is generally improved by increasing the alumina content and is thereby found to exhibit a fairly linear dependence on the measured Vickers hardness H{sub V} for a wide range of N and H{sub V} values. This finding highlights the important role of network topology in governing the SCCG in silicate glasses, since hardness has been shown to scale linearly with the number of atomic constraints. Our results therefore suggest that glasses showing under-constrained flexible networks, which feature floppy internal modes of deformation, are more readily attacked by water molecules, thus promoting stress corrosion and reducing the fatigue resistance.

  11. Structure and aqueous reactivity of silicate glasses high-resolution nuclear magnetic resonance contribution

    International Nuclear Information System (INIS)

    This research aims at getting a better understanding of the relations which may exist between the chemical composition of the oxide silicate glasses, the structure and the aqueous reactivity. We study the cations present in most glasses, more particularly the radioactive waste glasses, and those which are more liable to bring information both about structure and reactivity. Among the experimental methods used, the nuclear magnetic resonance of multi-quantum magic-angle spinning (NMR MQ-MAS) has been carried out for the structural characterization of the pristine and altered glasses. In the first part, we discuss the possibility of deducting a type of information from a quantitative approach of the 23Na, 27Al and 17O NMR MQ-MAS. In the second part, we apply this method to glasses containing between two and six oxides. The vitreous compositions studied permit to focus our attention on the influence of sodium, aluminum and calcium on their local structural environment. We point out an evolution of the distributions of bond distances and angles in relation to the glass chemical composition. We show the strong potentiality of the 17O used to probe the pristine and altered glasses. The influence of the different cations studied on the rate of glass dissolution is debated from the alterations made on short periods. On the basis of all these data, we discuss the importance of the structural effect which may influence the kinetic phenomena of alteration. (author)

  12. Reduction-induced inward diffusion and crystal growth on the surfaces of iron-bearing silicate glasses

    DEFF Research Database (Denmark)

    Liu, S.J.; Tao, H.Z.; Zhang, Y.F.;

    2015-01-01

    We investigate the sodium inward diffusion (i.e., sodium diffusion from surface toward interior) in iron containing alkaline earth silicate glasses under reducing conditions around Tg and the induced surface crystallization. The surface crystallization is caused by formation of a silicate-gel lay......+ ions have stronger bonds to oxygen and lower coordination number (4~5) than Ca2+, Sr2+ and Ba2+ ions. In contrast, a cristobalite layer forms in Ca-, Sr- and Ba-containing glasses....

  13. Internal friction of hydrated soda-lime-silicate glasses.

    Science.gov (United States)

    Reinsch, S; Müller, R; Deubener, J; Behrens, H

    2013-11-01

    The internal friction of hydrated soda-lime-silica glasses with total water content (C(W)) up to 1.9 wt. % was studied by dynamic mechanical analysis (DMA) using temperature-frequency sweeps from 723 K to 273 K and from 1 s(-1) to 50 s(-1). Total water content and concentrations of H2O molecules (C(H2O)) and OH groups (C(OH)) in the DMA specimens were determined by infrared spectroscopy. For low water contents (C(W) ≈ C(OH) 1 wt. %), where significant amounts of molecular water are evident (C(H2O) > 0.15 wt. %), however, internal friction spectra change unexpectedly: the β(OH) peak heights saturate and a low temperature shoulder appears on the β-relaxation peak. This emerging relaxation mode (β(H2O) relaxation) was assigned to the motions of H2O molecules. β(H2O) relaxation was found to be faster than β(OH) but slower than γ relaxation. Activation energy of the different relaxation modes increased in the order γ < β(H2O) < β(OH) < α. PMID:24206315

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

    Science.gov (United States)

    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.

  15. The short-range structure of alkali disilicate glasses by pulsed neutron total scattering

    International Nuclear Information System (INIS)

    Time-of-flight total neutron scattering experiments using pulsed neutrons with short wave-length produced by an electron linear accelerator have been carried out to measure the structure factors of SiO2 and M2O x 2 SiO2 (M = Li, Na and Li0.63Na0.37) glasses over a wide range of the scattering vector up to Q (= 4 π sin THETA/lambda) approx. 480 nm-1. The Placzek correction has been considered up to the second order in the energy transfer. The Fourier transforms of the structure factors yield the pair distribution functions highly resolved in real space, from which the stretching of the Si-O and O-O atomic distances and the number of bridging and non-bridging oxygen atoms in the alkali disilicate glass have been obtained. (orig.)

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

    Science.gov (United States)

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

    2016-04-01

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

  17. Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

    Energy Technology Data Exchange (ETDEWEB)

    Cochain, B; Neuville, D R; Roux, J; Strukelj, E; Richet, P [Physique des Mineraux et Magmas, Geochimie-Cosmochimie, CNRS-IPGP, 4 place Jussieu, 75005 Paris (France); Ligny, D de [Universite Claude Bernard Lyon 1, LPCML, F-69622 Villeurbanne (France); Baudelet, F, E-mail: cochain@ipgp.jussieu.f [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin (France)

    2009-11-15

    In Earth and Materials sciences, iron is the most important transition element. Glass and melt properties are strongly affected by iron content and redox state with the consequence that some properties (i.e. viscosity, heat capacity, crystallization...) depend not only on the amounts of Fe{sup 2+} and Fe{sup 3+}, but also on the coordination state of these ions. In this work we investigate iron redox reactions through XANES experiments at the K-edge of iron. Using a high-temperature heating device, pre-edge of XANES spectra exhibits definite advantages to make in-situ measurements and to determine the evolution of redox state with time, temperature and composition of synthetic silicate melts. In this study, new kinetics measurements are presented for a basalt melt from the 31,000-BC eruption of the Puy de Lemptegy Volcano in France. These measurements have been made between 773 K and at superliquidus temperatures up to 1923 K.

  18. Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

    International Nuclear Information System (INIS)

    In Earth and Materials sciences, iron is the most important transition element. Glass and melt properties are strongly affected by iron content and redox state with the consequence that some properties (i.e. viscosity, heat capacity, crystallization...) depend not only on the amounts of Fe2+ and Fe3+, but also on the coordination state of these ions. In this work we investigate iron redox reactions through XANES experiments at the K-edge of iron. Using a high-temperature heating device, pre-edge of XANES spectra exhibits definite advantages to make in-situ measurements and to determine the evolution of redox state with time, temperature and composition of synthetic silicate melts. In this study, new kinetics measurements are presented for a basalt melt from the 31,000-BC eruption of the Puy de Lemptegy Volcano in France. These measurements have been made between 773 K and at superliquidus temperatures up to 1923 K.

  19. Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

    Science.gov (United States)

    Cochain, B.; Neuville, D. R.; de Ligny, D.; Roux, J.; Baudelet, F.; Strukelj, E.; Richet, P.

    2009-11-01

    In Earth and Materials sciences, iron is the most important transition element. Glass and melt properties are strongly affected by iron content and redox state with the consequence that some properties (i.e. viscosity, heat capacity, crystallization...) depend not only on the amounts of Fe2+ and Fe3+, but also on the coordination state of these ions. In this work we investigate iron redox reactions through XANES experiments at the K-edge of iron. Using a high-temperature heating device, pre-edge of XANES spectra exhibits definite advantages to make in-situ measurements and to determine the evolution of redox state with time, temperature and composition of synthetic silicate melts. In this study, new kinetics measurements are presented for a basalt melt from the 31,000-BC eruption of the Puy de Lemptegy Volcano in France. These measurements have been made between 773 K and at superliquidus temperatures up to 1923 K.

  20. Gallium-containing phospho‐silicate glasses: Synthesis and in vitro bioactivity

    International Nuclear Information System (INIS)

    A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x = 1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga3+ concentration measured in solution is ∼ 6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome. - Highlights: ► A new class of potential bioactive glasses gallium content. ► Controlled ions release from the glass surface. ► Effect of Ga2O3 content on bioactivity (hydroxyapatite formation). ► Formation of calcite when the phosphate concentration is low in SBF.

  1. Insight into sodium silicate glass structural organization by multinuclear NMR combined with first-principles calculations

    International Nuclear Information System (INIS)

    Short and medium range order of silica and sodium silicate glasses have been investigated from a quantitative analysis of 29Si MAS NMR and 23Na, 17O MQMAS NMR spectra. The method described enables the extraction of the underlying 17O NMR parameter distributions of bridging oxygens (BOs) and non-bridging oxygens (NBOs), and yields site populations which are confirmed by 29Si NMR data. The extracted NMR parameter distributions and their variations with respect to the glass chemical composition can then be analyzed in terms of local structural features (bond angles and bond lengths, coordination numbers) with the help of molecular dynamics simulations combined with first-principles calculations of NMR parameters. Correlations of relevant structural parameters with 23Na, 29Si and 17O NMR interactions (isotropic chemical shift δ(iso), quadrupolar coupling constant C(Q) and quadrupolar asymmetry parameter ηQ are re-examined and their applicability is discussed. These data offer better insights into the structural organization of the glass network, including both chemical and topological disorder. Adding sodium to pure silica significantly diminishes the Si-O-Si bond angles and leads to a longer mean Si-O bond length with a slight decrease of the mean Na-O bond length. Moreover, the present data are in favor of a homogeneous distribution of Na around both oxygen species in the silicate network. Finally, our approach was found to be sensitive enough to investigate the effect of addition of a small quantity of molybdenum oxide (about 1 mol%) on the 17O MAS spectrum, opening new possibilities for investigating the Mo environment in silicate glasses. (authors)

  2. Characterization of radiative properties of Nd2O3 doped phosphate and silicate glasses for solid state laser

    International Nuclear Information System (INIS)

    Nd2O3 doped calcium aluminium phosphate and calcium aluminium silicate glasses prepared to compare their absorption and emission properties. Radiative lifetime of the excited state 4F3/2 derived by Judd-Ofelt theory applied to the absorption spectra. Using the photoluminescence spectrometer the steady state emission and relaxation time from excited energy level recorded under green light excitation. Phosphate glass has higher emission cross-section, higher radiative lifetime but less quantum efficiency due to non-radiative quenching through hydroxyl ions compared to silicate glass for Nd3+:4F3/2→4I9/2 emission

  3. The effect of nano scale inhomogeneity and silicate network connectivity on the activity of glasses with biological applications

    International Nuclear Information System (INIS)

    Classical molecular dynamics simulations of six soda-lime phospho silicate glasses are analyzed to identify correlations between specific structural features of the glasses and their biological activity, namely the dissolution in physiological fluids and the rate of deposition of a bone-like apatite film on their surface. Structural markers of the bioactivity can be identified in the silicate connectivity and the formation of nanometer-size calcium clusters separated from the silicate network, with the latter associated with less bioactive or bio-inactive compositions. The simulations show how these key structural features are affected by the glass composition, and suggest that different strategies (i.e. compositional ranges)can be employed to modify them in a rational and systematic way, in order to steer the biological activity of the glass towards the level required by different biomedical applications.

  4. Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; SHI Caijun; SONG Jianming

    2009-01-01

    The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated.Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re-placement of cement with 25% glass powder slightly decreases the strengthes at 7 and 28 d, but shows no effect on 90 d's. Silica fume is very effective in improving both the strength and chloride penetra-tion resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.

  5. Water cleaning ability and local structure of iron-containing soda-lime silicate glass

    International Nuclear Information System (INIS)

    A relationship between waste-water cleaning ability and local structure of iron-containing soda-lime silicate glass, 15Na2O·15CaO·xFe2O3·(70-x)SiO2 (x = 10–50 in mass%), abbreviated as NCFSx glass, was investigated by means of 57Fe-Mössbauer spectroscopy, redox titration with KMnO4 for the determination of chemical oxygen demand (COD) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Mössbauer spectra of NCFSx glass with “x” of 10 and 30 were composed of two doublets: one due to FeIIIO4 tetrahedra (Td) with isomer shift (δ) of 0.23–0.26 mm s − 1 and quadrupole splitting (Δ) 1.01–1.04 mm s − 1, and the other due to FeIIO6 octahedra (Oh) with δ of 1.00–1.03 mm s − 1 and Δ of 2.03–2.05 mm s − 1. Absorption area for FeII(Td) was decreased from 9.7 to 6.5 and 0.0 % when “x” was increased from 10 to 30 and 50. A leaching test performed with 500 mL of artificial waste water and 2.0 g of NCFS50 revealed waste-water cleaning ability of soda-lime glass, e.g., COD was reduced from 280 to 55.2 mg L − 1 after 10 day-leaching. After 10 day-leaching, it proved that iron was dissolved into waste water to a level of 5.3 7 x 10-1 mg L − 1. These results prove that organic matter could be effectively decomposed with iron-containing soda-lime silicate glass.

  6. Formation of color centers in a soda-lime silicate glass by excimer laser irradiation

    International Nuclear Information System (INIS)

    We have investigated defect generation in soda-lime silicate and iron-doped soda-lime silicate glasses by excimer laser irradiation in order to apply coloration due to radiation-induced defects as a coloring technique for practical glass products. The laser irradiation generated various kinds of defects, i.e., non-bridging oxygen hole centers (NBOHCs), E' centers, and trapped electron centers, as does x-ray and γ-ray irradiation. The amounts of generated NBOHCs, monitored by the absorption intensity, increased at first with the irradiation time for both the ArF and XeF lasers, and eventually became saturated. The saturated values for the ArF laser irradiation were almost the same regardless of the laser intensity, whereas those for the XeF laser irradiation were dependent on the intensity; a higher intensity generated a larger amount of NBOHCs. From the comparison of the energies of the photon and the absorption edge of the soda-lime silicate glasses, the defect generation reactions were expected to be one-photon and two-photon processes for the ArF and XeF lasers, respectively. In order to explain the defect generation behavior, we used a simple kinetic model in which the NBOHCs are reversibly generated and annihilated through the photo-reaction. The model includes a stretched exponential function, which is often observed for reactions occurring in amorphous materials. The dependences of the amounts of the generated NBOHCs on the irradiation time and intensity of the laser pulses derived from the model were consistent with the experimental results.

  7. Compositional investigation of ∼2 μm luminescence of Ho{sup 3+}-doped lead silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xueqiang; Huang, Feifei; Gao, Song [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Science, Beijing 100039 (China); Wang, Xin; Hu, Lili [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Chen, Danping, E-mail: dpchen2008@aliyun.com [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2015-11-15

    Graphical abstract: Ho{sup 3+}-doped lead silicate glass with lowest maximum phonon energy possesses highest ∼2 μm luminescence intensity. - Highlights: • With increment of lead oxide, maximum phonon energy in lead silicate glass decreased. • ∼2 μm luminescent intensity of Ho{sup 3+} increased with increment of lead oxide. • Lowest lead oxide content glass possesses highest quantum efficiency due to low maximum phonon energy. - Abstract: Lead silicate glass samples with varying lead oxide content were prepared in this study, and their luminescent properties were examined and analyzed. It was found that with increasing lead oxide content, the maximum phonon energies of the glass samples decreased, while their spontaneous transition probabilities first increased and then decreased. The influence of the spontaneous transition rate, A{sub 10}, and the multi-phonon relaxation rate, W{sub 10}, on the sample luminescent properties was analyzed using rate equations. As a result, it was found that with increasing lead oxide content, W{sub 10}/A{sub 10} decreased, while the quantum efficiency increased. Thus, the luminescent intensity at ∼2 μm increased in the glass samples with increased lead oxide content. The high luminescent intensity and long lifetime indicate that silicate glasses containing high levels of lead oxide could potentially be used in ∼2 μm lasers.

  8. Optical waveguides in Er3+/Yb3+-codoped silicate glasses fabricated by proton implantation

    Science.gov (United States)

    Liu, Chun-Xiao; Fu, Li-Li; Zhu, Xu-Feng; Guo, Hai-Tao; Li, Wei-Nan; Lin, She-Bao; Wei, Wei

    2016-07-01

    In this work, a planar waveguide was fabricated by proton implantation in Er3+/Yb3+-codoped silicate glasses with energies of (500 + 550) keV and fluences of (1 + 2) × 1016 ions/cm2. The end-face coupling method was employed to determine whether the light could be confined in the waveguide or not. The prism coupling technique was applied to measure the guided mode spectrum and the intensity calculation method was used to construct the refractive index profile. With the profile, a near-field intensity distribution was calculated by the finite difference beam propagation method. The obtained results may be helpful in developing integrated optical devices.

  9. Intense 1.6 μm fluorescence of Nd3+ doped cadmium bismuth silicate glasses

    International Nuclear Information System (INIS)

    In this work, Judd-Ofelt analysis is applied to rare-earth (RE = Nd3+) doped cadmium bismuth silicate (20CdO⋅xSiO2⋅(79.5−x)Bi2O3⋅0.5Nd2O3 (CSBN)) glasses in order to evaluate their potential as well as both glass laser systems and optical materials. The phenomenological Judd-Ofelt parameters (Ω2, Ω4, Ω6) are determined for RE ions with their quality factors and compared with the equivalent parameters for several other hosts. The calculated value of stimulated emission cross-section for 4F3/2→4I11/2 has high and varies 14.72×10−20 to 9.66×10−20 cm2 with Bi2O3 content in the host glass. The results point out that the glass system is good candidate for the development of photonics devices which are operating near infrared spectral range. Further, the FTIR results reveal that the glasses have BiO6, SiO4 and non-bridging oxygen as local structure

  10. Effects of thermo-plasmonics on laser-induced backside wet etching of silicate glass

    Science.gov (United States)

    Tsvetkov, M. Yu; Yusupov, V. I.; Minaev, N. V.; Timashev, P. S.; Golant, K. M.; Bagratashvili, V. N.

    2016-10-01

    The thermo-plasmonic effect (heat deposition via absorption of laser light by metal nanoparticles) is applied to substantially enhance the effectiveness and controllability of the microstructure formation by laser-induced backside wet etching (LIBWE). Experiments were carried out with silicate glass plates using a pulsed 527 nm wavelength laser and an aqueous solution of AgNO3 as a precursor of the Ag nanoparticles. Mechanisms of such thermo-plasmonic LIBWE (TP-LIBWE) versions are considered. They involve: laser-induced photo-thermal reducing of silver (Ag) and self-assembling of Ag nanoparticles in water and the water/glass interface; fast laser-induced overheating of a water and glass surface through the thermo-plasmonic effect; formation of highly reactive supercritical water that causes glass etching and crater formation; generation of steam-gas bubbles in a liquid. It is significant that the emergence of the Marangoni convection results in bubble retention in the focal point at the interface and the accumulation of nanoparticles on the surface of the laser-induced crater, as this facilitates the movement of the bubbles with captured Ag particles from the fluid volume in the crater region, and accelerates the formation of the area of strong ‘surface absorption’ of laser energy. All these mechanisms provide a highly efficient and reproducible process for laser microstructure formation on the surface of glass using a novel TP-LIBWE technique.

  11. NMR Study on Structural Characteristics of Rare Earth Doped Boro-Alumino-Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The structural characteristics of Re2O3 doped B2O3-Al2O3-SiO2 glasses and factors such as the component and heat-treating conditions affecting the glass structure were investigated by magic angle spin nuclear magnetic resonance(MAS NMR) spectroscopy and differential thermal analysis (DTA). It is found that, in B2O3-Al2O3-SiO2 glass, the boron coordination sites are mainly of trigonal (B(3)) and tetrahedral (B(4)), and the aluminum coordination sites are Al(4), Al(5) and partly of Al(6). With the increase of BaO content in the B2O3-Al2O3-SiO2 glass, B(3) gradually changes to B(4), and Al(5), Al(6) changes to Al(4). On the other hand, compared with Ba2+, RE3+ can accumulate the boron network because of its higher field strength, which results in a large network structure. With the increase of samarium oxide, the silicate coordination Q4 (3T) will have predominance gradually. Heat-treatment has little effect on the boron and aluminum coordination sites in the glass structure.

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

    International Nuclear Information System (INIS)

    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 29Si NMR spectroscopy. The local structure of glass aluminosilicates as observed by NMR, is presented with analysis of the information content of 29Si spectra. A high-temperature (to 13000C) 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 (T1 and T2) measurements as a function of composition and temperature for 23Na and 29Si

  13. Some effects of γ-irradiation in soda-lime silicate glasses

    International Nuclear Information System (INIS)

    Nanosized metallic silver particles have been formed in multicomponent commercial soda-lime silicate glasses partly substituted with ionic silver and irradiated at room temperature by γ-rays from a 60Co-source (1.33 MeV). To characterize the obtained composites, combined measurements of thermally stimulated depolarization current and optical absorption, accompanied by microspectrophotometric analysis and electron microscopy observations have been used. It has been shown that γ-irradiation might be an effective means to modify and control the concentration, size and spatial distribution of the dopant within the near-surface layer of the glass-matrix. This procedure also allows the conversion of some glassy areas in this region into a partially crystalline material with improved mechanical characteristics

  14. ESR and spectral studies of Er3+ ions in soda-lime silicate glass

    International Nuclear Information System (INIS)

    Electron spin resonance (ESR), optical absorption spectra and photoluminescence spectra of Er3+ ions in soda-lime silicate glasses doped with different concentrations of Er2O3 have been studied. The glasses of the composition (in mol%) (65-x)SiO2:25Na2O:10CaO:xEr2O3 (where x=0.02, 0.05, 0.1, 0.3, 0.5, 1, 2, 3, 4 and 5) were prepared by the melt quenching method. ESR measurements were carried out at room temperature down to 1.62 K. Absorption spectra were investigated in the UV-VIS-NIR region from 300 to 1800 nm. Photoluminescence spectra were observed in the spectral range 500-800 nm under 514.5 nm argon-ion laser line excitation.

  15. Sub-nanoscale nanoimprint fabrication of atomically stepped glassy substrates of silicate glass and acryl polymer

    Science.gov (United States)

    Yoshimoto, Mamoru

    2015-11-01

    In the nanoimprint process, the resolution limit of patterning has attracted much attention from both scientific and industrial aspects. In this article, we briefly review the main achievements of our research group on sub-nanoscale nanoimprint fabrication of atomically patterned glassy substrates of oxide glass and polymer. By applying the sapphire (α-Al2O3 single crystal) wafers with self-organized nanopatterns of atomic steps as thermal nanoimprinting molds, we successfully transferred their nanoscale patterns onto the surfaces of glassy substrates such as soda-lime silicate glasses and poly(methyl methacrylate) polymers. The surfaces of nanoimprinted glassy materials exhibited regularly arrayed atomic stairs with 0.2-0.3 nm step height, which were in good agreement with the sub-nanopatterns of sapphire molds. These atomically stepped morphologies on the glassy substrates were found to be stable for about 1 year.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Fluorescence and radiative properties of Nd3+ ions doped zinc bismuth silicate glasses

    International Nuclear Information System (INIS)

    Graphical abstract: Fluorescence spectra of ZBSN5 glass (Inset: Energy levels depicting the various lasing transitions of Nd3+ ions (4F3/2 → 4I9/2,11/2)) -- Highlights: • Hypersensitive bands of Nd3+ (4I9/2 → 4G5/2, 2G7/2; 586 nm) ions are shifted. • Fluorescence studies show that ZBSN glasses may be used as lasing materials. • Bi3+ cations are incorporated in the glass network as [BiO6] octahedral units. -- Abstract: Glasses having composition 20ZnO⋅xSiO2⋅(79.5−x)Bi2O3⋅0.5Nd2O3 with x varying from 10 to 50 mol% have been synthesized. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. Optical absorption and fluorescence spectra were measured at ambient temperature. This paper reports on different physical and absorption spectral properties of Nd3+ doped zinc bismuth silicate glasses with varying content of Bi2O3 to understand its influences on hypersensitive band intensities. From the recorded absorption spectra, Judd–Ofelt intensity parameters Ωλ = (λ = 2, 4, 6) have been evaluated with their quality factors and are used to compute the radiative properties of Nd3+ glasses. The calculated Judd–Ofelt parameters are found to decreasing with decrease in Bi2O3 content in the glass which may be due to the decrease in Nd–O bond covalency. From these intensity parameters various radiative properties like spontaneous emission probability (Arad), radiative life time (τr), fluorescence branching ratio (βr) and stimulated emission cross-section (σ) for various emission bands have been calculated. The stimulated emission cross-section of fluorescence transition 4F3/2 → 4I11/2 have high values and varies from 15.19 × 10−20 cm2 to 5.73 × 10−20 cm2 with Bi2O3 content in the host glass. The results point out this glass system as good candidate to be used in the development of photonics devices operating in the near infrared spectral range. Further, the FTIR results reveal that the glasses have BiO6, SiO4 and non

  18. Unusual anti-thermal degradation of bismuth NIR luminescence in bismuth doped lithium tantalum silicate laser glasses.

    Science.gov (United States)

    Tan, Linling; Wang, Liping; Peng, Mingying; Xu, Shanhui; Zhang, Qinyuan

    2016-08-01

    For application of bismuth laser glasses in either fiber amplifier or laser, their performance stability in long run should be understood especially in extreme conditions. However, so far, there are few reports on it. Here, we found, after the cycle experiments on heating and cooling, that the proper increase of lithium content in lithium tantalum silicate laser glass can lead to unusual anti-thermal degradation of bismuth NIR luminescence, which completely differs from the scenario in germanate glass. FTIR, 29Si MAS NMR spectra, absorption and dynamic photoluminescence spectra are employed to unravel how this happens. The results illustrate that it should be due to the decrease of polymerization of silicate glass network, which in turn allows the regeneration at 250°C, and therefore, the content increase of bismuth NIR emission centers. In the meanwhile, we noticed though Bi luminescence can be thermally quenched its peak does not shift along with temperature, which seldom appears in laser materials. The unique property might guarantee the unshift of Bi fiber laser wavelength once such glass was made into fiber devices even as the environmental temperature changes. The role of lithium is discussed in the evolution of glass structures, the suppression of glass heterogeneity, and the thermal stability of Bi luminescence, and it should be helpful to design homogeneous silicate laser glass with outstanding thermal stability. PMID:27505827

  19. 化学增强铝硅酸盐玻璃扩散性能研究%The Diffusion Performance of Potassium and Sodium in Ion Exchanged Aluminum Silicate Glass

    Institute of Scientific and Technical Information of China (English)

    程金树; 赵薇; 肖子凡

    2012-01-01

    了解碱金属离子在玻璃表面的扩散对生产高强度铝硅酸盐系统离子交换玻璃具有重要意义.通过外加Al,讨论不同Al/Na对碱离子扩散影响.采用EPMA测得玻璃断面K+、Na+分布曲线,根据Boltzmann- Matano计算方法得到K+、Na+的扩散系数,根据Arrhenius公式计算得到K+、Na+的扩散活化能.实验证明,随着Al/Na的增加,K+、Na+扩散深度逐渐增加,互扩散系数逐渐增加,K+、Na+平均活化能逐渐增加.讨论玻璃体内Al/Na比例是研究高强度离子交换玻璃的一个重要方向.%In the production of ion exchanged aluminum silicate system glass, the alkali ion diffusion on the glass surface is an important process which must be considered. In this paper, we discussed the impact of additional Al on the diffusion of alkali ions. The penetration depth profiles of alkali ions were obtained by EPMA methods. The diffusion coefficients of alkali ions were calculated by Boltzmann-Matano equation. And the active energy of alkali ions were gotten by Arrhenius equation. The results showed that the penetration depth, the interdiffusion coefficient and the average active energy increased with the increase of Al/Na ratios. It means the Al/Na ratios have a great effect on the diffusion of alkali i-ons.

  20. Photoluminescence of atomic gold and silver particles in soda-lime silicate glasses

    International Nuclear Information System (INIS)

    We report the chemistry and photophysics of atomic gold and silver particles in inorganic glasses. By synchrotron irradiation of gold-doped soda-lime silicate glasses we could create and identify unambiguously the gold dimer as a stable and bright luminescing particle embedded in the glassy matrix. The gold dimer spectra coincide perfectly with rare gas matrix spectra of Au2. The glass matrix is, however, stable for years, and is hence perfectly suited for various applications. If the irradiated gold-doped sample is annealed at 550 deg. C a bright green luminescence can be recognized. Intense 337 nm excitation induces a decrease of the green luminescence and the reappearance of the 753 nm Au2 emission, indicating a strong interrelationship between both luminescence centers. Time-dependent density functional theory (TD-DFT) calculations indicate that the green luminescence can be assigned to noble metal dimers bound to silanolate centers. These complexes are recognized as the first stages in the further cluster growth process, which has been investigated with small-angle x-ray scattering (SAXS). In silver-doped glasses, Ag deg. atoms can be identified with electron paramagnetic resonance (EPR) spectroscopy after synchrotron activation. Annealing at 300 deg. C decreases the concentration of Ag1, but induces an intense white light emission with 337 nm excitation. The white luminescence can be decomposed into bands that are attributed to small silver clusters such as Ag2, Ag3 and Ag4, and an additional band matching the green emission of gold-doped glasses

  1. Silicate Based Glass Formulations for Immobilization of U.S. Defense Wastes Using Cold Crucible Induction Melters

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Gary L.; Kim, Dong-Sang; Schweiger, Michael J.; Marra, James C.; Lang, Jesse B.; Crum, Jarrod V.; Crawford, Charles L.; Vienna, John D.

    2014-05-22

    The cold crucible induction melter (CCIM) is an alternative technology to the currently deployed liquid-fed, ceramic-lined, Joule-heated melter for immobilizing of U.S. tank waste generated from defense related reprocessing. In order to accurately evaluate the potential benefits of deploying a CCIM, glasses must be developed specifically for that melting technology. Related glass formulation efforts have been conducted since the 1990s including a recent study that is first documented in this report. The purpose of this report is to summarize the silicate base glass formulation efforts for CCIM testing of U.S. tank wastes. Summaries of phosphate based glass formulation and phosphate and silicate based CCIM demonstration tests are reported separately (Day and Ray 2013 and Marra 2013, respectively). Combined these three reports summarize the current state of knowledge related to waste form development and process testing of CCIM technology for U.S. tank wastes.

  2. Photo-acoustic spectroscopy and quantum efficiency of Yb3+ doped alumino silicate glasses

    International Nuclear Information System (INIS)

    In this contribution, we analyze the effect of several preparation methods of Yb3+ doped alumino silicate glasses on their quantum efficiency by using photo-acoustic measurements in comparison to standard measurement methods including the determination via the fluorescence lifetime and an integrating sphere setup. The preparation methods focused on decreasing the OH concentration by means of fluorine-substitution and/or applying dry melting atmospheres, which led to an increase in the measured fluorescence lifetime. However, it was found that the influence of these methods on radiative properties such as the measured fluorescence lifetime alone does not per se give exact information about the actual quantum efficiency of the sample. The determination of the quantum efficiency by means of fluorescence lifetime shows inaccuracies when refractive index changing elements such as fluorine are incorporated into the glass. Since fluorine not only eliminates OH from the glass but also increases the “intrinsic” radiative fluorescence lifetime, which is needed to calculate the quantum efficiency, it is difficult to separate lifetime quenching from purely radiative effects. The approach used in this contribution offers a possibility to disentangle radiative from non-radiative properties which is not possible by using fluorescence lifetime measurements alone and allows an accurate determination of the quantum efficiency of a given sample. The comparative determination by an integrating sphere setup leads to the well-known problem of reabsorption which embodies itself in the measurement of too low quantum efficiencies, especially for samples with small quantum efficiencies

  3. FMR Study of the Porous Silicate Glasses with Fe3O4 Magnetic Nanoparticles Fillers

    Directory of Open Access Journals (Sweden)

    B. Zapotoczny

    2012-01-01

    Full Text Available The results of research on new magnetic materials for biomedical applications are discussed. These materials are porous silicate glasses with magnetic fillers. To ensure the smallest number of components for subsequent removal from the body, the magnetic fillers are bare magnetite nanoparticles (Fe3O4. The magnetic properties of these materials have been investigated using the ferromagnetic resonance method (FMR. The FMR analysis has been complemented by scanning electron microscope (SEM measurements. In order to examine the effect of time degradation on filling the porous glass with bare magnetite nanoparticles the FMR measurement was repeated five months later. For the samples with high degree of pore filling, in contrast to the samples with low degree of pore filling, the FMR signal was still strong. The influence of different pH values of magnetite nanoparticles aqueous suspension on the degree of filling the pores of glasses is also discussed. The experimental results are supported by computer simulations of FMR experiment for a cluster of N magnetic nanoparticles locked in a porous medium based on a stochastic version of the Landau-Lifshitz equation for nanoparticle magnetization.

  4. Photo-acoustic spectroscopy and quantum efficiency of Yb{sup 3+} doped alumino silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Stefan, E-mail: stefan.kuhn84@googlemail.com; Tiegel, Mirko; Herrmann, Andreas; Rüssel, Christian [Otto-Schott-Institute of Materials Research, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany); Engel, Sebastian; Wenisch, Christoph; Gräf, Stephan; Müller, Frank A. [Otto-Schott-Institute of Materials Research, Jena University, Löbdergraben 32, 07743 Jena (Germany); Körner, Jörg; Seifert, Reinhard; Yue, Fangxin; Klöpfel, Diethardt [Institute of Optics and Quantum Electronics, Jena University, Max-Wien-Platz 1, 07743 Jena (Germany); Hein, Joachim; Kaluza, Malte C. [Institute of Optics and Quantum Electronics, Jena University, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz-Institute Jena, Fröbelstieg 3, 07743 Jena (Germany)

    2015-09-14

    In this contribution, we analyze the effect of several preparation methods of Yb{sup 3+} doped alumino silicate glasses on their quantum efficiency by using photo-acoustic measurements in comparison to standard measurement methods including the determination via the fluorescence lifetime and an integrating sphere setup. The preparation methods focused on decreasing the OH concentration by means of fluorine-substitution and/or applying dry melting atmospheres, which led to an increase in the measured fluorescence lifetime. However, it was found that the influence of these methods on radiative properties such as the measured fluorescence lifetime alone does not per se give exact information about the actual quantum efficiency of the sample. The determination of the quantum efficiency by means of fluorescence lifetime shows inaccuracies when refractive index changing elements such as fluorine are incorporated into the glass. Since fluorine not only eliminates OH from the glass but also increases the “intrinsic” radiative fluorescence lifetime, which is needed to calculate the quantum efficiency, it is difficult to separate lifetime quenching from purely radiative effects. The approach used in this contribution offers a possibility to disentangle radiative from non-radiative properties which is not possible by using fluorescence lifetime measurements alone and allows an accurate determination of the quantum efficiency of a given sample. The comparative determination by an integrating sphere setup leads to the well-known problem of reabsorption which embodies itself in the measurement of too low quantum efficiencies, especially for samples with small quantum efficiencies.

  5. Time-resolved luminescence studies of Eu3+ in soda-lime silicate glasses

    International Nuclear Information System (INIS)

    Soda-lime glasses doped with Eu3+ were synthesized using a variety of compositions, namely changing the fraction of CaO or Eu2O3. Those glasses were characterized with several techniques, including ellipsometry, UV–vis–NIR absorption spectroscopy, steady-state photoluminescence spectroscopy and time-resolved luminescence. The compositions' effects on optical properties such as refraction indexes, Eu3+ oscillator strengths and luminescence lifetimes were accessed from the analysis of the experimental results. Judd–Ofelt theory was used to analyze all these aspects, which allow the detection of a mismatch of optical properties from absorption and emission spectroscopy. This mismatch was confirmed from the time-resolved data, showing the existence of two different spectroscopic Eu3+ species. From those results it is concluded that there is evidence for lanthanide aggregation, giving rise to self-quenching effects that may be described through resonance energy transfer mechanisms. The difference between luminescence lifetimes for isolated and aggregated Eu(III) is interpreted as due to different interactions with oxygen in the matrix, namely degree of covalency of the Eu–O bond and point group symmetry of the lanthanide. -- Highlights: • Time resolved luminescence studies of Eu(III) in soda-lime silicate glass show the existence of two different species. • Mismatch of Judd–Ofelt parameters are obtained from absorption and emission spectroscopy. • Eu(III) has less clustering tendency when Eu2O3 concentration decreases and when CaO concentration increases

  6. Analytical boron diffusivity model in silicon for thermal diffusion from boron silicate glass film

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2015-09-01

    An analytical boron diffusivity model in silicon for thermal diffusion from a boron silicate glass (BSG) film has been proposed in terms of enhanced diffusion due to boron-silicon interstitial pair formation. The silicon interstitial generation is considered to be a result of the silicon kick-out mechanism by the diffused boron at the surface. The additional silicon interstitial generation in the bulk silicon is considered to be the dissociation of the diffused pairs. The former one causes the surface boron concentration dependent diffusion. The latter one causes the local boron concentration dependent diffusion. The calculated boron profiles based on the diffusivity model are confirmed to agree with the actual diffusion profiles measured by secondary ion mass spectroscopy (SIMS) for a wide range of the BSG boron concentration. This analytical diffusivity model is a helpful tool for p+ boron diffusion process optimization of n-type solar cell manufacturing.

  7. The research of properties of Eu3+-doped cadmium aluminium silicate glass

    Science.gov (United States)

    Chen, Yue-e.; Hou, Lan-tian; Song, Zhao-yuan

    2008-11-01

    We have prepared (40SiO2-14Al2O3-(40-x) CdO-2Li2O-2K2O-2Na2O -x Eu2O3) cadmium aluminium silicate glasses doped with europium by high temperature solid-state reaction method. The absorption spectra, excitation spectra, emission spectra are obtained. With the increase of Eu2O3, the absorption peaks are founded increasing to the best doped concentration and then reducing, which is nonlinear relationship. The charge-transfer band is moved to 320 nm due to the addition of Cd2+. We can see that the ratio of peak in 591 nm and 615 nm is 0.6-0.75 in general, and is unrelated to doped concentration. By changing concentration of Eu3+.We can adjust and mix different intensity of light according to the demand.

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

    International Nuclear Information System (INIS)

    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. 29Si 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. - Graphical abstract: The morphologies and microstructures of acid-catalyzed mesoporous bioactive glass microspheres (MBGMs-A) and acid-alkali co-catalyzed mesoporous bioactive glass microspheres (MBGMs-B) were observed by scanning electron microscope and transmission electron microscope. MBGMs-A exhibits a dense structure and a porous can be observed in MBGMs-B. The microspheres have a quick inducing-apatite formation ability and show a sustained release of alendronate (AL). Highlights: • A rapid method was reported to prepare mesoporous bioactive glass microspheres. • The addition of ammonia significantly shortens the preparation time. • Acid and acid-alkali co-catalyzed microspheres were studied for the first time. • The materials exhibited excellent in vitro bioactivity and drug

  9. Effect of ZnO on the Physical Properties and Optical Band Gap of Soda Lime Silicate Glass

    OpenAIRE

    Mohd Sabri Mohd Ghazali; Mohd Hafiz Mohd Zaid; Azmi Zakaria; Sidek Hj. Abdul Aziz; Khamirul Amin Matori

    2012-01-01

    This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass ...

  10. Formation of silver colloids on ion exchanged soda lime silicate glasses by irradiation

    International Nuclear Information System (INIS)

    The effect of ionizing radiation (gamma rays, X-rays and electrons) on soda lime silicate glasses, in which part of the Na+ was substituted by Ag+ by means of an ionic exchange process, was studied. The techniques of thermally stimulated depolarization current (TSDC) and transmission electron microscopy (TEM) were employed to follow the formation of silver colloids by irradiation. Also the thermoluminescence (TL) of the samples was measured and three peaks between room temperature and 450 C were observed. The TEM and TSDC results agree that, as expected, ionizing radiation promotes the formation of silver colloids on the ion exchanged surface of soda lime glasses. Soft X-rays are much more efficient in the process than gamma rays and electrons. The correlation with thermoluminescence glow curves indicates that the intensity of a TL peak at 230 C can provide a rapid means of evaluating the presence of silver colloids. TL sensitivities, measured as area under the glow curve per unit mass and unit dose, are very similar for ion exchanged and not exchanged samples submitted to X-ray irradiation, although the peak temperatures differ in about 40 C in the two cases. For both electron and gamma irradiated samples, the TL sensitivity drops about an order of magnitude when compared to the X-ray irradiated ones. (orig.)

  11. CHARACTERIZATION OF COMMERCIALLY AVAILABLE ALKALI RESISTANT GLASS FIBER FOR CONCRETE REINFORCEMENT AND CHEMICAL DURABILITY COMPARISON WITH SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS SYSTEM GLASSES

    Directory of Open Access Journals (Sweden)

    Göktuğ GÜNKAYA

    2012-12-01

    Full Text Available According to the relevant literature, the utilization of different kind of glass fibers in concrete introduces positive effect on the mechanical behavior, especially toughness. There are many glassfibers available to reinforce concretes. Glass fiber composition is so important because it may change the properties such as strength, elastic modulus and alkali resistance. Its most important property to be used in concrete is the alkali resistance. Some glasses of SrO–MgO–ZrO2–SiO2 (SMZS quaternary system, such as 26SrO, 20MgO, 14ZrO2, 40SiO2 (Zrn glass, have been found to be highly alkali resistant thanks to their high ZrO2 and MgO contents. Previous researches on these glasses with MnO and/or Fe2O3 partially replacing SrO have been made with the aim of improving the chemical resistance and decreasing the production cost.The main target of the present study, first of all, was to characterize commercially available alkali resistant glass fiber for concrete reinforcement and then to compare its alkali durability with those of the SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS system glasses. For such purposes, XRF, Tg-DTA, alkali resistance tests and SEM analysis conducted with EDX were employed. According tothe alkali endurance test results it was revealed that some of the SMFMZS system glass powders are 10 times resistant to alkali environments than the commercial glass fibers used in this study.Therefore, they can be considered as alternative filling materials on the evolution of chemically resistant concrete structures.

  12. Strengthening mechanisms and fracture surface characteristics of silicate glass matrix composites with inclusion of alumina particles of different particle sizes

    International Nuclear Information System (INIS)

    Strengthening mechanisms of silicate glass by the inclusion of alumina particles of different volume fractions and different particle sizes are reported. The formulas of three responsible strengthening mechanisms, based on inclusion/crack interactions and interfacial elemental diffusion, were deduced; these include crack deflection, crack bridging and interdiffusion. The strength of the glass/alumina composites increased with inclusion fraction, but followed strengthening mechanisms that varied with alumina particle size. Crack deflection and bridging mechanisms dominated in strengthening for the glass/alumina (at mean particle size of 6 μm) composites while interdiffusion mechanism played a major role in the glass/alumina (at mean particle size of 1 μm) composites. The theoretical deduction of strengthening mechanisms depending on the particle size of alumina inclusions was demonstrated by the experimental strength data and fracture surface characteristics of the glass/alumina composites

  13. Effect of Li2O content on physical and structural properties of vanadyl doped alkali zinc borate glasses

    International Nuclear Information System (INIS)

    The effect of Li2O content in vanadyl doped 20ZnO+xLi2O+(30-x)Na2O+50B2O3 (5≤x≥25) glasses has been studied with respect to their physical and structural properties. The absence of sharp peaks in XRD spectra of these glass samples confirms the amorphous nature. The physical parameters like density, refractive index, ionic concentration and electronic polarizability vary non-linearly with x mol% depending on the diffusivities of alkali ions. EPR and optical absorption spectra reveal that the resonance signals are characteristics of VO2+ ions in tetragonally compressed octahedral site. Spin-Hamiltonian, crystal field, tetragonal field and bonding parameters are found to be in good agreement with the other reported glass systems. The tetragonal distortion (gperpendicular-g||) and Dt reveals that their values vary non-linearly with Li2O content and reaches a minimum at x=10 mol%. An anomaly of character has been observed in all the properties of vanadyl doped glass systems, which gives a clear indication of mixed alkali effect.

  14. Effect of Li 2O content on physical and structural properties of vanadyl doped alkali zinc borate glasses

    Science.gov (United States)

    Raghavendra Rao, T.; Rama Krishna, Ch.; Udayachandran Thampy, U. S.; Venkata Reddy, Ch.; Reddy, Y. P.; Sambasiva Rao, P.; Ravikumar, R. V. S. S. N.

    2011-05-01

    The effect of Li 2O content in vanadyl doped 20ZnO+ xLi 2O+(30- x)Na 2O+50B 2O 3 (5≤ x≥25) glasses has been studied with respect to their physical and structural properties. The absence of sharp peaks in XRD spectra of these glass samples confirms the amorphous nature. The physical parameters like density, refractive index, ionic concentration and electronic polarizability vary non-linearly with x mol% depending on the diffusivities of alkali ions. EPR and optical absorption spectra reveal that the resonance signals are characteristics of VO 2+ ions in tetragonally compressed octahedral site. Spin-Hamiltonian, crystal field, tetragonal field and bonding parameters are found to be in good agreement with the other reported glass systems. The tetragonal distortion ( g⊥- g∥) and Dt reveals that their values vary non-linearly with Li 2O content and reaches a minimum at x=10 mol%. An anomaly of character has been observed in all the properties of vanadyl doped glass systems, which gives a clear indication of mixed alkali effect.

  15. Characterization of Cr3+ doped mixed alkali ions effect in zinc borate glasses - Physical and spectroscopic investigations

    Science.gov (United States)

    Rama Sundari, G.; Pushpa Manjari, V.; Raghavendra Rao, T.; Satish, D. V.; Rama Krishna, Ch.; Venkata Reddy, Ch.; Ravikumar, R. V. S. S. N.

    2014-06-01

    The physical and structural properties of Cr3+ doped 19.9 ZnO + xLi2O + (30 - x) Na2O + 50B2O3 (5 ⩽ x ⩽ 25) (ZLNB) glasses have been studied. Powder X-ray diffraction patterns indicated the amorphous nature of the glass samples. The physical parameters of all the glasses were also evaluated with respect to the composition. They exhibit the non-linearity providing the evidence for mixed alkali ions effect. The infrared spectra of the glasses in the range 400-4000 cm-1 showed the presence of BO3 and BO4 local structures in all the glass systems. No boroxol ring formation was observed in the structure of these glasses. Optical absorption and electron paramagnetic resonance studies were carried out at room temperature. From the optical absorption data various optical parameters such as optical band gap, Urbach energy were evaluated. Crystal field and Racah parameters are evaluated from optical absorption spectra. The EPR spectra of Cr3+ doped ZLNB glasses exhibited resonance signals at g = 4.066 and g = 1.9779 characteristic of Cr3+ ions. The evaluated bonding parameters suggest the covalent nature.

  16. Computational modelling of large deformations in layered-silicate/PET nanocomposites near the glass transition

    Science.gov (United States)

    Figiel, Łukasz; Dunne, Fionn P. E.; Buckley, C. Paul

    2010-01-01

    Layered-silicate nanoparticles offer a cost-effective reinforcement for thermoplastics. Computational modelling has been employed to study large deformations in layered-silicate/poly(ethylene terephthalate) (PET) nanocomposites near the glass transition, as would be experienced during industrial forming processes such as thermoforming or injection stretch blow moulding. Non-linear numerical modelling was applied, to predict the macroscopic large deformation behaviour, with morphology evolution and deformation occurring at the microscopic level, using the representative volume element (RVE) approach. A physically based elasto-viscoplastic constitutive model, describing the behaviour of the PET matrix within the RVE, was numerically implemented into a finite element solver (ABAQUS) using an UMAT subroutine. The implementation was designed to be robust, for accommodating large rotations and stretches of the matrix local to, and between, the nanoparticles. The nanocomposite morphology was reconstructed at the RVE level using a Monte-Carlo-based algorithm that placed straight, high-aspect ratio particles according to the specified orientation and volume fraction, with the assumption of periodicity. Computational experiments using this methodology enabled prediction of the strain-stiffening behaviour of the nanocomposite, observed experimentally, as functions of strain, strain rate, temperature and particle volume fraction. These results revealed the probable origins of the enhanced strain stiffening observed: (a) evolution of the morphology (through particle re-orientation) and (b) early onset of stress-induced pre-crystallization (and hence lock-up of viscous flow), triggered by the presence of particles. The computational model enabled prediction of the effects of process parameters (strain rate, temperature) on evolution of the morphology, and hence on the end-use properties.

  17. Equation of state of refractory silicate glasses and melts by high-pressure x-ray microtomography

    Science.gov (United States)

    Lesher, C. E.; Gaudio, S.; Wang, Y.; Nishiyama, N.; Rivers, M.; Tangeman, J.

    2005-12-01

    The new high-pressure x-ray tomographic microscope on 13-BM-D at GSECARS-APS/ANL is being used to determine the equation of state of glasses and melts. We demonstrate that the volume of compressed silicate glass microspheres can be measured accurately to constrain the bulk modulus and its pressure derivative up to ~6 GPa. The pressure generation system consists of two opposing Drickamer anvils compressed within an x-ray-transparent Al containment ring supported by thrust bearings and driven by a 250-ton hydraulic press. This configuration permits the pressure cell to rotate under load, while collecting 360 x-ray radiographs through 180 degrees of rotation. Individual x-ray radiographs are recorded by a CCD camera after conversion to visible light by a YAG scintillator and combined to render the volume using a back-projection algorithm and standard flat/dark field corrections with minimal filtering, following by image processing. Results are reported for two magnesium silicate glasses (33 mol % and 38 mol % SiO2) synthesized by levitation-laser heating. Vitreous forsterite (33 mol % SiO2) compressed to 4.8 GPa shows a 5% reduction in volume, while 38 mol % SiO2 glass compressed to 6.4 GPa shows an 8.7% decrease in volume - corresponding to bulk moduli of 75 and 55 GPa, respectively, for K' of 4. The differences in the compressibility of these magnesium silicate glasses are consistent with the structural differences inferred from neutron and x-ray diffraction studies. Efforts to develop a heating circuit will soon allow the recovery of thermal expansivity, central to efforts to derive a P-V-T equation of state for silicate liquids relevant to the Earth's deep interior.

  18. Electron and x-ray photon radiation effects on surfaces of lead silicate glasses

    International Nuclear Information System (INIS)

    Radiation effects on insulators have been extensively studied in terms of radiation induced damage. However, little work has concentrated on in situ surface modification during irradiation and the evolution of surface relaxation after the termination of irradiation. In this work, 1.3 keV electrons and 1.2536 keV Mg Kα X-ray photons were applied to investigate radiation effects on surface structural changes during irradiation and relaxation. The microstructure and composition of lead silicate glass were investigated in situ in an ultra-high-vacuum (UHV) environment by X-ray Photoelectron Spectroscopy (XPS). Similar surface radiation effects were observed using both types of radiation which included permanent metallic lead separation from the glass network resulting from Pb-O bond breaking, bimodal distribution of the O 1s XPS signal due to bridging and non-bridging oxygens, gradual increase of total lead and silicon concentrations and gradual decrease of oxygen concentration during relaxation. Different radiation effects for electron beam and X-ray photons were also observed. For photon irradiation, silicon and lead continuously accumulated while the oxygen on the surface continuously decreased during irradiation and relaxation. In the case of electron irradiation, both silicon and lead were depleted from the surface during irradiation and accumulated during relaxation. Opposite concentration changes were observed for oxygen; it increased during irradiation and decreased during relaxation. The experimental results are discussed in terms of charge effects, secondary electron yield, field-enhanced diffusion, non-bridging oxygens and nucleation of metallic lead

  19. Volumetric properties of magnesium silicate glasses and supercooled liquid at high pressure by X-ray microtomography

    Science.gov (United States)

    Lesher, Charles E.; Wang, Yanbin; Gaudio, Sarah; Clark, Alisha; Nishiyama, Nori; Rivers, Mark

    2009-05-01

    The volumetric properties of silicate glasses and supercooled liquid are examined at high pressures and temperatures using X-ray computed tomography (CT) and absorption. The high pressure X-ray microtomography (HPXMT) system at the Advanced Photon Source, Argonne National Laboratory (GeoSoilEnvironCARS 13-BM-D beamline) consists of two opposing anvils compressed within an X-ray-transparent containment ring supported by thrust bearings and loaded using a 250-ton hydraulic press. This system permits the pressure cell to rotate under the load, while collecting radiographs through at least 180° of rotation. The 13-BM-D beamline permits convenient switching between monochromatic radiation required for radiography and polychromatic radiation for pressure determination by energy dispersive diffraction. We report initial results on several refractory magnesium silicate glasses synthesized by levitation laser heating. Volume changes during room temperature compression of Mg-silicate glasses with 33 mol% and 38 mol% SiO 2 up to 11.5 GPa give an isothermal bulk moduli of 93-100 GPa for a K' of 1. These values are consistent with ultrasonic measurements of more silica-rich glasses. The volumetric properties of amorphous MgSiO 3 at 2 GPa were examined during annealing up to 1000 °C. We consider the consequences of heating through the glass transition and the implications for thermal expansivity of supercooled liquids at high pressure. Our results illustrate the capabilities of HPXMT for studies of refractory glasses and liquids at high pressure and offer strategies for future studies of liquid densities within the melting interval for magmas in planet interiors.

  20. Effect of ZnO on the Physical Properties and Optical Band Gap of Soda Lime Silicate Glass

    Directory of Open Access Journals (Sweden)

    Mohd Sabri Mohd Ghazali

    2012-06-01

    Full Text Available This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS glass combined with zinc oxide (ZnO that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.

  1. Study of fluorine in silicate glass with 19F nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Duncan, T. M.; Douglass, D. C.; Csencsits, R.; Walker, K. L.

    1986-07-01

    We report an application of nuclear magnetic resonance (NMR) spectroscopy to the study of fluorine-doped silicate glass prepared by the modified chemical vapor deposition process, prior to drawing the rod into fibers. The silica contains 1.03-wt. % fluorine, as determined by the calibrated intensity of the 19F NMR spectrum. The isotropic chemical shift of the 19F spectrum shows that fluorine bonds only to silicon; there is no evidence of oxyfluorides. Analysis of the distribution of nuclear dipolar couplings between fluorine nuclei reveals that the relative populations of silicon monofluoride sites [Si(O-)3F] and species having near-neighbor fluorines, such as silicon difluoride sites [Si(O-)2F2], are nearly statistically random. That is, to a good approximation, the fluorine substitutes randomly into the oxygen sites of the silica network. There is no evidence of local clusters of fluorine sites, silicon trifluoride sites [Si(O-)F3], or silicon tetrafluoride (SiF4).

  2. Gamma irradiated soda lime silicate glasses of different origin: Isothermal light emission

    International Nuclear Information System (INIS)

    The isothermal light emission, at temperatures from 30 to 70 deg. C, from gamma irradiated (9 kGy with 60Co source, at room temperature) soda lime silicate glasses, with different amounts of K, Na and/or Ca in the matrix is presented. This emission was not expected in view of the thermoluminescent (TL) peak temperatures, commensurate with low probability of emission at temperatures too much below the peak maxima. It was noticed that single or multi-exponential decay functions can be fitted to experimental data for all the samples. The time constants of luminescence decay obtained range from minutes to several hours, depending on sample composition and temperature. For each sample and temperature, there is a tendency of enlargement of the half life of the light emission for longer heating duration. As the TL mechanism of this material is not yet fully understood, the analysis included, correlated with already known results of other techniques, gives a contribution to its comprehension

  3. Photodarkening of Infrared Irradiated Yb3+-Doped Alumino-Silicate Glasses: Effect on UV Absorption Bands and Fluorescence Spectra

    OpenAIRE

    Hrvoje Gebavi; Daniel Milanese; Stefano Taccheo; David Mechin; Achille Monteville; Francesca S. Freyria; Barbara Bonelli; Thierry Robin

    2013-01-01

    The photodarkening phenomenon in alumino-silicate glass preforms, doped with different ytterbium concentrations, was studied. The UV band, comprised between 180 and 350 nm, was examined before and after irradiation at 976 nm. The non-linear dependence of 240 nm band with concentration after infra-red irradiation was demonstrated and ascribed predominantly to Yb3+ pair’s interaction. The emission spectrum after the excitation in UV spectral region showed increased intensity after photodarkenin...

  4. Dissolution mechanism of soda-lime silicate glass and of PNL 76-68 in the presence of dissolved Mg

    International Nuclear Information System (INIS)

    Leaching studies were performed on powdered PNL 76-68 glass in de-ionized water in the presence of Mg solute. The results showed that the presence of Mg in the leachant greatly reduced the rate of glass dissolution. The equation Q = ktα was used to express the experimental data. In the absence of Mg, α was about 1, i.e., the amount of glass dissolved was linear with time. In the presence of Mg, α was close to 0.5, i.e. the extracted amount was proportional to the square root of time. Therefore, the reduction of the dissolution rate of PNL 76-68 glass in the presence of Mg solute could be explained as a result of a change in the glass dissolution mechanism. Comparative leaching studies on bulk soda-lime silicate glass in a sodium borate buffered system (pH 8.1) showed the same results. The presence of Mg in the leachant reduced the rate of glass dissolution. In the absence of Mg, α was about 1, while in the presence of Mg, α was 0.5. This change in α was not caused by changes in pH, and it represents a real change in the glass dissolution mechanism

  5. Investigation of UV-photon induced hydrophilicity of titanium ion-implanted soda-lime silicate glasses

    International Nuclear Information System (INIS)

    The UV-induced wetting effect on titanium oxide surface is well-known; however, the UV-induced hydrophilicity of titanium implanted soda-lime silicate glass has not been investigated. Hence the contact angle of water droplet under the indoor fluorescent lights on titanium-ion implanted soda-lime silicate glasses was investigated. The silicate glasses were implanted by MEVVA ion implanter by 40 keV titanium ions with a fluence of 1015 ions cm-2. The contact angle, the chemical bonding environment, and surface morphologies were examined. Results show the formation of TiO2, the increase of surface roughness, and the reduction of the contact angle after the ion implantation. Further enhancement of hydrophilicity after the 254 nm pre-UV irradiation for 1 h on the implanted sample surface was observed. The enhancement of the wetting effect after ion implantation could be attributed to rougher TiO2 content surface. However, according to the mechanisms of UV photo-induced hydrophilicity on TiO2 proposed previously, the enhancement of hydrophilicity of titanium implanted surface with and without 254 nm pre-photon radiation can be attributed to not only the reduction of hydrocarbon on surface during the UV radiation but also to the oxygen vacancies produced by 254 nm UV photon irradiation.

  6. Fire Resistance of Wood Impregnated with Soluble Alkaline Silicates

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Giudice

    2007-01-01

    Full Text Available The aim of this paper is to determine the fire performance of wood panels (Araucaria angustifolia impregnated with soluble alkaline silicates. Commercial silicates based on sodium and potassium with 2.5/1.0 and 3.0/1.0 silica/alkali molar ratios were selected; solutions and glasses were previously characterized. Experimental panels were tested in a limiting oxygen chamber and in a two-foot tunnel. Results displayed a high fire-retardant efficiency using some soluble silicates.

  7. A new approach for understanding ion transport in glasses; example of complex alkali diborate glasses containing lead, bismuth and tellurium oxides

    Indian Academy of Sciences (India)

    V C Veeranna Gowda; C Narayana Reddy; K J Rao

    2013-02-01

    Mechanism of ion transport in glasses continues to be incompletely understood. Several of the theoretical models in vogue fail to rationalize conductivity behaviour when d.c. and a.c. measurements are considered together. While they seem to involve the presence of at least two components in d.c. activation energy, experiments fail to reveal that feature. Further, only minor importance is given to the influence of structure of the glass on the ionic conductivity behaviour. In this paper, we have examined several general aspects of ion transport taking the example of ionically conducting glasses in pseudo binary, Na2B4O7.(1−) M$_{a}$O$_{b}$ (with = 0.25–0.79 and M$_{a}$O$_{b}$ = PbO, TeO2 and Bi2O3) system of glasses which have also been recently characterized. Ion transport in them has been studied in detail. We have proposed that non-bridging oxygen (NBO) participation is crucial to the understanding of the observed conductivity behaviour. NBO–BO switching is projected as the first important step in ion transport and alkali ion jump is a subsequent event with a characteristically lower barrier which is, therefore, not observed in any study. All important observations in d.c. and a.c. transport in glasses are found consistent with this model.

  8. Effect of γ-irradiation on the electrical conductivity of some soda lime silicate glass containing blast furnace slag

    International Nuclear Information System (INIS)

    The effect of electric field strength on conduction in soda lime silicate glass doped with blast furnace slag with different concentration was studied and the value of jump distance was calculated. The structure and the mixed anion effect in the conductivity have been examined by measuring the electrical conductivity of glass samples at temperature ranging between 20 and 250 deg. C. The results showed that the electrical conductivity of the examined glasses are divided into three ranges depending on the temperature range. The first is from room temperature to about 49.5 deg. C, the second is at a temperature range of 60.3-104 deg. C where the glass shows a decrease in its conductivity with the increase in temperature. This was followed by another increase in the electrical conductivity with the increase in temperature. The results also showed that the glass becomes more insulating as the slag content increased. The effect of irradiation was also studied by exposing glass samples to two different irradiation doses. It can be noticed that irradiation causes an increase in the electrical conductivity, especially at high temperature. The results were discussed and correlated according to the molecular structure of the prepared glass

  9. Irradiations effects on the structure of boro-silicated glasses: long term behaviour of nuclear waste glassy matrices

    International Nuclear Information System (INIS)

    This work deals with the long term behaviour of R7T7-type nuclear waste glasses and more particularly of non-active boro-silicated glasses made up of 3 or 5 oxides. Radioactivity of active glasses is simulated by multi energies ions implantations which reproduce the same defects. The damages due to the alpha particles are simulated by helium ions implantations and those corresponding to the recoil nucleus are obtained with gold ions ones. Minor actinides, stemming from the used fuel, is simulated by trivalent rare-earths (Eu3+ and Nd3+). In a first part, we have shown by macroscopic experiments (Vickers hardness - swelling) and optical spectroscopies (Raman - ATR-IR) that the structure of the glassy matrices is modified under implantations until a dose of 2,3.1013 at.cm-2, which corresponds to a R7T7 storage time estimated at 300 years. Beyond this dose, no additional modifications have been observed. The second part concerns the local environment of the rare-earth ions in glasses. Two different environments were found and identified as follows: one is a silicate rich one and the other is attributed to a borate rich one. (author)

  10. Molecular dynamics study of the influence of mobile cations on the reconstruction of an irradiated silicate glass

    International Nuclear Information System (INIS)

    The effect of ballistic collisions in a simplified nuclear glass was investigated by molecular dynamics. Systematic results were obtained in the 0-16 keV energy range. Following a damage peak, reconstruction of the glass structure was observed in terms of the overall degree of polymerization. The reconstruction was facilitated by the presence of mobile cations. The dynamics of restoration of the SiO4 tetrahedrons during displacement cascades and during the formation of a structure from a random configuration can be fitted to curves corresponding to the same analytic formula. This similarity allowed us to examine the influence of mobile cations (alkalis or alkaline earths) on the formation of SiO4 entities in smaller systems formed from random configurations. The formation rate of SiO4 tetrahedrons accelerates with the Na2O or CaO percentage to reach a maximum rate above about 10 mol% Na2O or CaO. This threshold corresponds to the disappearance in the glass structure of zones comprising a central bridging oxygen surrounded by two first-neighbor bridging oxygen rings. No mixed alkali effect was observed in systems containing both Na and Cs because the formation of SiO4 does not require long-range diffusion of mobile cations

  11. Observation of Supercontinuum Generation and Darkening Effect in Bro-Silicate Glass under 800 nm Femtosecond Irradiations

    Science.gov (United States)

    Abdolahpour, D.; Jamshidi-Ghaleh, K.

    2007-04-01

    In this paper, we report the experimental observations of supercontinuum generation and darkening effect in bro-silicate glasses under 200 femtosecond pulses at wavelength of 800 nm. The spectrum of supercontinuum emission from the sample is recorded in the UV wavelength range. The length of filamentation or white light and darkening are investigated at different incident laser pulse energies. The begging position of the generated white light and darkening moves inside glass bulk with decreasing of incident pulse energy. The pulse energy threshold for supercontinuum generation and the laser-induced darkening in this material has been measured. By controlling of the laser-induced darkening in borosilicate glasses prepares a promising technique for designing optical devices.

  12. Infrared spectroscopy and hydrogen isotope geochemistry of hydrous silicate glasses. Progress report, June 1, 1996--May 31, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, S.; Stolper, E.

    1998-06-01

    This DOE-funded project (DE-FG03-ER13445, 6/1/96-5/31/99) emphasizes study of the behavior of volatiles in magmatic systems. The project is explicitly focused on the combined application of IR spectroscopy, experimental petrology, and stable isotope geochemistry to understanding the behavior and properties of the volatile components dissolved in silicate melts and glasses, although in recent years, our emphasis has broadened to include non-volatile aspects of stable isotope geochemistry. Results obtained during the current grant and previous grant periods confirm that when applied to study of well-chosen synthetic and natural systems, the combination of these approaches and techniques can yield insights of general petrological and volcanological value and of practical value to DOE. In particular, the results of our DOE-funded work has led to a deeper understanding of the physical chemistry of silicate melts as well as specific constraints on the thermal and chemical evolution of high-level magmatic systems of the sort being evaluated as potential geothermal and magmathermal energy sources. Moreover, our work has also contributed to understanding the behavior of H-, C-, and O-bearing species in amorphous and crystalline silicates, including the kinetics of their interactions; we believe these results will contribute to efforts to use silicates in the development of nuclear waste disposal strategies.

  13. Spectroscopic studying of silicate glasses subjected to photon and ion fluxes

    International Nuclear Information System (INIS)

    A preliminary exposure of glass to UV-and γ-radiation activates the ion synthesis of glass within glass as it causes the increase of number of broken bonds in glass structural net through stimulation of the processes of chemical interaction of the implants with their neighbors. (authors)

  14. UV-curable silicate phosphor planar films printed on glass substrate for white light-emitting diodes.

    Science.gov (United States)

    Jang, Jin Woo; Kim, Jun Sik; Kwon, Oh Hyeon; Lee, Tae Hyeon; Cho, Yong Soo

    2015-08-15

    We suggest a simple way of forming a nonconventional remote phosphor layer for white light-emitting diodes. A printing technology using a paste consisting of yellow (Ba,Sr,Ca)(2)SiO(4):Eu(2+) silicate phosphor and ultraviolet (UV)-curable polymer is applied to form solid planar films on a common soda lime silicate glass substrate through UV radiation. Relative content of the phosphor was adjusted for the best dispersion of the phosphor particles in the polymer matrix with better emission and luminescence performance. As a result, the 70 wt. % phosphor-embedded film has a luminous efficacy of ∼70.1  lm/W at 200 mA. PMID:26274644

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

    International Nuclear Information System (INIS)

    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 Na2CO3 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

  16. Multidiffusion mechanisms for noble gases (He, Ne, Ar) in silicate glasses and melts in the transition temperature domain: Implications for glass polymerization

    Science.gov (United States)

    Amalberti, Julien; Burnard, Pete; Laporte, Didier; Tissandier, Laurent; Neuville, Daniel R.

    2016-01-01

    Noble gases are ideal probes to study the structure of silicate glasses and melts as the modifications of the silicate network induced by the incorporation of noble gases are negligible. In addition, there are systematic variations in noble gas atomic radii and several noble gas isotopes with which the influence of the network itself on diffusion may be investigated. Noble gases are therefore ideally suited to constrain the time scales of magma degassing and cooling. In order to document noble gas diffusion behavior in silicate glass, we measured the diffusivities of three noble gases (4He, 20Ne and 40Ar) and the isotopic diffusivities of two Ar isotopes (36Ar and 40Ar) in two synthetic basaltic glasses (G1 and G2; 20Ne and 36Ar were only measured in sample G1). These new diffusion results are used to re-interpret time scales of the acquisition of fractionated atmospheric noble gas signatures in pumices. The noble gas bearing glasses were synthesized by exposing the liquids to high noble gas partial pressures at high temperature and pressure (1750-1770 K and 1.2 GPa) in a piston-cylinder apparatus. Diffusivities were measured by step heating the glasses between 423 and 1198 K and measuring the fraction of gas released at each temperature step by noble gas mass spectrometry. In addition we measured the viscosity of G1 between 996 and 1072 K in order to determine the precise glass transition temperature and to estimate network relaxation time scales. The results indicate that, to a first order, that the smaller the size of the diffusing atom, the greater its diffusivity at a given temperature: D(He) > D(Ne) > D(Ar) at constant T. Significantly, the diffusivities of the noble gases in the glasses investigated do not display simple Arrhenian behavior: there are well-defined departures from Arrhenian behavior which occur at lower temperatures for He than for Ne or Ar. We propose that the non-Arrhenian behavior of noble gases can be explained by structural modifications

  17. Intense 1.6 μm fluorescence of Nd{sup 3+} doped cadmium bismuth silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pal, I., E-mail: ip-gjust@yahoo.com; Agarwal, A., E-mail: ip-gjust@yahoo.com; Sanghi, S., E-mail: ip-gjust@yahoo.com [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001, Haryana (India); Bhardwaj, S. [Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat-131093, Haryana (India); Sanjay [Department of Applied Science and Humanities, Rawal Institute of Engineering and Technology, Fridabad-121006, Haryana (India)

    2014-04-24

    In this work, Judd-Ofelt analysis is applied to rare-earth (RE = Nd{sup 3+}) doped cadmium bismuth silicate (20CdO⋅xSiO{sub 2}⋅(79.5−x)Bi{sub 2}O{sub 3}⋅0.5Nd{sub 2}O{sub 3} (CSBN)) glasses in order to evaluate their potential as well as both glass laser systems and optical materials. The phenomenological Judd-Ofelt parameters (Ω{sub 2}, Ω{sub 4}, Ω{sub 6}) are determined for RE ions with their quality factors and compared with the equivalent parameters for several other hosts. The calculated value of stimulated emission cross-section for {sup 4}F{sub 3/2}→{sup 4}I{sub 11/2} has high and varies 14.72×10{sup −20} to 9.66×10{sup −20} cm{sup 2} with Bi{sub 2}O{sub 3} content in the host glass. The results point out that the glass system is good candidate for the development of photonics devices which are operating near infrared spectral range. Further, the FTIR results reveal that the glasses have BiO{sub 6}, SiO{sub 4} and non-bridging oxygen as local structure.

  18. Effects of beta/gamma radiation on nuclear waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-07-01

    A key challenge in the disposal of high-level nuclear waste (HLW) in glass waste forms is the development of models of long-term performance based on sound scientific understanding of relevant phenomena. Beta decay of fission products is one source of radiation that can impact the performance of HLW glasses through the interactions of the emitted {beta}-particles and g-rays with the atoms in the glass by ionization processes. Fused silica, alkali silicate glasses, alkali borosilicate glasses, and nuclear waste glasses are all susceptible to radiation effects from ionization. In simple glasses, defects (e.g., non-bridging oxygen and interstitial molecular oxygen) are observed experimentally. In more complex glasses, including nuclear waste glasses, similar defects are expected, and changes in microstructure, such as the formation of bubbles, have been reported. The current state of knowledge regarding the effects of {beta}/{gamma} radiation on the properties and microstructure of nuclear waste glasses are reviewed. (author)

  19. Effects of beta/gamma radiation on nuclear waste glasses

    International Nuclear Information System (INIS)

    A key challenge in the disposal of high-level nuclear waste (HLW) in glass waste forms is the development of models of long-term performance based on sound scientific understanding of relevant phenomena. Beta decay of fission products is one source of radiation that can impact the performance of HLW glasses through the interactions of the emitted β-particles and g-rays with the atoms in the glass by ionization processes. Fused silica, alkali silicate glasses, alkali borosilicate glasses, and nuclear waste glasses are all susceptible to radiation effects from ionization. In simple glasses, defects (e.g., non-bridging oxygen and interstitial molecular oxygen) are observed experimentally. In more complex glasses, including nuclear waste glasses, similar defects are expected, and changes in microstructure, such as the formation of bubbles, have been reported. The current state of knowledge regarding the effects of β/γ radiation on the properties and microstructure of nuclear waste glasses are reviewed. (author)

  20. Modelling the evaporation of boron species. Part 1: Alkali-free borosilicate glass melts

    NARCIS (Netherlands)

    Limpt, J.A.C. van; Beerkens, R.G.C.; Cook, S.; O'Connor, R.; Simon, J.

    2011-01-01

    A laboratory test facility has been used to measure the boron evaporation rates from borosilicate glass melts. The impact of furnace atmosphere composition and glass melt composition on the temperature dependent boron evaporation rates has been investigated experimentally. In Part 1 of this paper th

  1. The Structural Role of Zr within Alkali Borosilicate Glasses for Nuclear Waste Immobilisation

    Energy Technology Data Exchange (ETDEWEB)

    A Connelly; N Hyatt; K Travis; R Hand; E Maddrell; R Short

    2011-12-31

    Zirconium is a key constituent element of High Level nuclear Waste (HLW) glasses, occurring both as a fission product and a fuel cladding component. As part of a wider research program aimed at optimizing the solubility of zirconium in HLW glasses, we have investigated the structural chemistry of zirconium in such materials using X-ray Absorption Spectroscopy (XAS). Zirconium K-edge XAS data were acquired from several inactive simulant and simplified waste glass compositions, including a specimen of blended Magnox/UO{sub 2} fuel waste glass. These data demonstrate that zirconium is immobilized as (octahedral) six-fold coordinate ZrO{sub 6} species in these glasses, with a Zr-O contact distance of 2.09 {angstrom}. The next nearest neighbors of the Zr species are Si at 3.42 {angstrom} and possibly Na at 3.44 {angstrom}, no next nearest neighbor Zr could be resolved.

  2. CRYSTALLIZATION AND THERMAL EXPANSION CHARACTERISTICS OF In2O3-CONTAINING LITHIUM IRON SILICATE-DIOPSIDE GLASSES

    OpenAIRE

    *S. M. Salman; S.N. Salama

    2011-01-01

    The crystallization characteristics of glasses based on lithium iron silicate (LiFeSi2O6)-diopside (CaMgSi2O6) composition with addition of Al2O3 at the expense of Fe2O3 were described. The effect of LiInSi2O6/CaMgSi2O6 replacements was also investigated. The thermal treatment, the crystal phases, and the micro-structural properties of (LiFeSi2O6–CaMgSi2O6) glasses, replacing partial Fe2O3 with Al2O3 and partial CaMgSi2O6 with LiInSi2O6, have been studied by a differential thermal analysis, a...

  3. Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Ae [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Abo-Mosallam, Hany A. [Glass Research Department, National Research Centre, Dokki, Cairo (Egypt); Lee, Hye-Young [Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of); Kim, Gyu-Ri [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Kim, Hae-Won [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of); Lee, Hae-Hyoung, E-mail: haelee@dku.edu [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of)

    2014-09-01

    The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO{sub 2}-P{sub 2}O{sub 5}-CaO-ZnO-MgO{sub (1-X)}-SrO{sub X}-CaF{sub 2} (X = 0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X = 0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X = 0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues. - Highlights: • We developed multicomponent glass compositions for a novel aluminum-free glass ionomer cement (GIC). • The effects of MgO replacement with SrO in the glasses on the mechanical properties and cell proliferation were evaluated. • Substitution of MgO with SrO at low levels led to improvement of mechanical properties and cell viability of the cements. • Microstructural degradations in the cement matrix of the GICs with strontium at high levels were observed after aging.

  4. Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses

    International Nuclear Information System (INIS)

    The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO2-P2O5-CaO-ZnO-MgO(1-X)-SrOX-CaF2 (X = 0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X = 0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X = 0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues. - Highlights: • We developed multicomponent glass compositions for a novel aluminum-free glass ionomer cement (GIC). • The effects of MgO replacement with SrO in the glasses on the mechanical properties and cell proliferation were evaluated. • Substitution of MgO with SrO at low levels led to improvement of mechanical properties and cell viability of the cements. • Microstructural degradations in the cement matrix of the GICs with strontium at high levels were observed after aging

  5. Effect of cerium oxide addition on electrical and physical properties of alkali borosilicate glasses

    International Nuclear Information System (INIS)

    The study of electrical conductivity, density and coefficient of thermal expansion (CTE) of Na2O:K2O:B2O3:SiO2:BaO glass samples with addition of cerium oxide has been carried out. It has been observed that the addition of cerium oxide affects the electrical conductivity, density and CTE. The results have been explained on the basis of the variation in number of bridging oxygens (BOs) and non-bridging oxygens (NBOs) present in the glass. In general, the glass with more NBOs has a weak network which exhibits higher electrical conductivity. The weakening of the network has been supported by the observed decrease in density and increase in CTE for the glasses.

  6. Alkali-Phosphate Glasses Containing WO3 and Nb2O5

    Directory of Open Access Journals (Sweden)

    L. Bih

    2013-01-01

    Full Text Available New phosphate glasses in the quaternary system (50-x A2O-x WO3-10 Nb2O5-40 P2O5, with x = 0; 30 and A = Li or Na were prepared by the melt quenching method. The effect on the crystallization behaviour of the glass due to the introduction of WO3 into the glass composition and, consequently, the diminishing of the molar amount of the alkaline oxide and the decreasing of the molar ratio between network modifiers and network formers (M/F was studied. The prepared glasses were heat-treated in air, at 550°C, 600°C, and 650°C for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA, X-ray powder diffraction (XRD, and Raman spectroscopy and the morphology by scanning electron microscopy (SEM. It was found that the replacement of Li2O or Na2O by WO3 reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses, the presence of WO3 promotes the formation of NbOPO4 instead of the LiNbO3 phase and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AW40-glasses.

  7. Thermally activated conversion of a silicate gel to an oxyfluoride glass ceramic: Optical study using Eu3+ probe ion

    International Nuclear Information System (INIS)

    Sol–gel route using metal alkoxides precursor and trifluoroacetic acid as in situ fluorination reagent has been used to prepare Eu3+-doped silicate xerogel, followed by thermal annealing to obtain oxyfluoride glass ceramic containing Eu3+-doped BaF2 nanocrystals. We have used Eu3+ as probe ion and we analyzed its characteristic features (photoluminescence, optical absorption and magnetic circular dichroism) to get information about the local environment around the ion during thermally activated evolution of the sol to xerogel and then glass ceramic. As the drying and annealing proceeds silica network is formed accompanied by precipitation of the nanofluoride crystalline phase; Eu3+ coordination changes gradually from a random and assymetric CF3COO- one (in the sol) to a symmetric one (in the BaF2 nanocrystals) given by the fluorine ions. Glass ceramization is based on a homogenous crystallization mechanism with BaF2 nucleation centres resulted from thermal decomposition of Ba-trifluoacetate at around 300 °C followed by subsequent growth into BaF2 nanocrystals above 600 °C; Eu3+-ions are incorporated during the nanocrystals growth. -- Highlights: • Glass ceramization is the result of a homogenous crystallization with BaF2 nucleation centres. • Eu3+-ions are incorporated during nanocrystals growth, above 600 °C. • Eu3+-ions are embedded dominantly in the BaF2 nanocrystals in high symmetry sites

  8. Evolution of mechanical properties of silicate glasses: Impact of the chemical composition and effects of irradiation

    International Nuclear Information System (INIS)

    This thesis examines: (1) how the chemical composition changes the hardness, toughness, and stress corrosion cracking behavior in model pristine and (2) how external irradiation impact these properties. It is to be incorporated in the context of the storage of nuclear waste in borosilicate glass matrix, the structural integrity of which should be assessed. Eight simplified borosilicate glasses made of 3 oxides with modulated proportions (SiO2-B2O3-Na2O (SBN) have been selected and their hardness, toughness, and stress corrosion cracking behavior have been characterized prior and after irradiation. The comparative study of the non-irradiated SBN glasses provides the role played by the chemical composition. The sodium content is found to be the key parameter: As it increases, the glass plasticity increases, leading to changes in the mechanical response to strain. Hardness (Hv) and toughness (Kc) decrease since the flow under indenter increases. The analysis of the stress corrosion behavior evidences a clear shift of the SCC curves linked also to the glass plasticity. Four of the 8 simplified SBN glass systems highlight the influence of electron, light and heavy ions irradiations on the mechanical properties. Once again, the sodium content is a key parameter. It is found to inhibit the glass modification: Glasses with high sodium content are more stable. Ions irradiations highlight the predominant role of nuclear interaction in changing the glass properties. Finally, electronic interaction induced by helium and electron irradiation does not lead to the same structural/mechanical glasses variations. (author)

  9. Microstructural studies on some silicate and phosphate based glass-ceramics

    International Nuclear Information System (INIS)

    Recent developments have made it possible to make a new class of ceramic materials called glass-ceramics with tailored expansion coefficients and improved thermo-mechanical and corrosion resistance properties. Since these are formed by controlled crystallization in which crystallites are embedded in the glassy matrix, it is possible to make nano glass-ceramics having pronounced effect of particle size on various properties such as transparency, bioactivity, etc. In this talk, some of the recent results on micro-structural properties of a few glass-ceramic-to-metal sealants and bio-glass-ceramics are discussed

  10. Solid-state autocatalysis and oscillatory reactions in silicate glass systems

    DEFF Research Database (Denmark)

    Canning, John; Sørensen, Henrik Rokkjær; Kristensen, Martin

    2006-01-01

    We report the first demonstration of autocatalysis and oscillatory behaviour in the solid-state where no decomposition process is involved. Our material system is solid-state silica glass impregnated with hydrogen. It is at the heart of photosensitivity in glass-based optical waveguides and devic...

  11. Effect of natural and synthetic iron corrosion products on silicate glass alteration processes

    Science.gov (United States)

    Dillmann, Philippe; Gin, Stéphane; Neff, Delphine; Gentaz, Lucile; Rebiscoul, Diane

    2016-01-01

    Glass long term alteration in the context of high-level radioactive waste (HLW) storage is influenced by near-field materials and environmental context. As previous studies have shown, the extent of glass alteration is strongly related to the presence of iron in the system, mainly provided by the steel overpack around surrounding the HLW glass package. A key to understanding what will happen to the glass-borne elements in the geological disposal lies in the relationship between the iron-bearing phases and the glass alteration products formed. In this study, we focus on the influence of the formation conditions (synthetized or in-situ) and the age of different iron corrosion products on SON68 glass alteration. Corrosion products obtained from archaeological iron artifacts are considered here to be true analogues of the corrosion products in a waste disposal system due to the similarities in formation conditions and physical properties. These representative corrosion products (RCP) are used in the experiment along with synthetized iron anoxic corrosion products and pristine metallic iron. The model-cracks of SON68 glass were altered in cell reactors, with one of the different iron-sources inserted in the crack each time. The study was successful in reproducing most of the processes observed in the long term archaeological system. Between the different systems, alteration variations were noted both in nature and intensity, confirming the influence of the iron-source on glass alteration. Results seem to point to a lesser effect of long term iron corrosion products (RCP) on the glass alteration than that of the more recent products (SCP), both in terms of general glass alteration and of iron transport.

  12. Micro-Brillouin spectroscopy mapping of the residual density field induced by Vickers indentation in a soda-lime silicate glass

    OpenAIRE

    H. Tran; Clément, S.; Vialla, R.; Vandembroucq, D.; Rufflé, B.

    2012-01-01

    High-resolution Brillouin scattering is used to achieve 3-dimensional maps of the longitudinal acoustic mode frequency shift in soda-lime silicate glasses subject to Vickers indentations. Assuming that residual stress-induced effects are simply proportional to density changes, residual densification fields are obtained. The density gradient is nearly isotropic, confirming earlier optical observations made on a similar glass. The results show that Brillouin micro-spectroscopy opens the way to ...

  13. 阳离子对硅酸盐玻璃激光拉曼光谱影响的研究%Influence of Cations on the Laser Raman Spectra of Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    熊义; 赵虹霞; 干福熹

    2012-01-01

    Na2O(K2O)-CaO(MgO)-SiO2, Na2O(K2O)-A12O3-SiO2, Na2O(K2O)-B2Q3-SiOz, Na2O(K2O)-PbO-SiO2 and PbO-BaO-SiO2 glass systems were investigated using laser Raman spectroscopic technique. The modification of short-range structure of glass caused by network modifier cations will influence Raman signature. Alkali and alkali-earth ions can weaken the bridging oxygen bond, thus lower the frequency of Si-Ob-Si anti-symmetric stretching vibration. When coordinated by oxygen ions, B3+ can form [BO4] tetrahedron and enter the silicon-oxygen network, but this effect had little impact on the frequency of Raman peaks located in the high-frequency region. Al3+ can also be coordinated by oxygen ions to form [A1O4 ] tetrahedron. [ AlO4 ] will increase the disorder degree of network while entering network. Ba2+ can increase the density of electron cloud along the Si-Onb bond when it bonds with non-bridging oxygen, which will lead to a higher peak intensity of O-Si-O stretching vibration. The Raman peaks of alkli- and alkali-earth silicate glasses are mainly distributed in the region of 400~1 200 cm-1, while in the spectrum of Na2O(K2O)-PbO-SiO2 glass system a 131 cm-1 peak existed. The authors assigned it to the Pb-O symmetric stretching vibration. Some of the samples were produced in the laboratory according to the average compositions of ancient glasses, so this research is very significant to discriminating ancient silicate glasses of different systems by Laser Raman spectroscopic technique.%运用拉曼光谱技术研究了Na2O (K2O) CaO( MgO)-SiO2,Na2O (K2O)- Al2-O3-SiO2,Na2O(K2O)-B2O3-SiO2,Na2O(K2O)-PbO-SiO2和PbO-BaO-SiO2五个系统的玻璃.结果表明,阳离子对玻璃近程结构的改造会引起拉曼特征的变化.部分样品是根据古玻璃平均成分在实验室烧制的,这项研究对于运用激光拉曼光谱区分不同系统的古代硅酸盐玻璃有重要意义.

  14. Inorganic glasses and glass-ceramics studied by isothermal mechanical spectroscopy

    International Nuclear Information System (INIS)

    This paper describes isothermal mechanical spectroscopy measurements carried out in silicate glasses and LAS (Li2O-Al2O3-SiO2)-type glass-ceramics. Single alkali silicate glass Na2O.3SiO2 exhibits two relaxation peaks. The first one located at a low temperature is generally assigned to the stress-induced diffusion of alkali ions. The second relaxation peak is attributed to the 'non-bridging oxygen'. Mixed alkali silicate glasses (1 - x)Na2O.xLi2O.3SiO2 with x = 0, 0.25, 0.5, 0.75 exhibit the mixed alkali peak. And also the 'non-bridging oxygen' peak. Two LAS-type glass-ceramics having the same chemical composition but different microstructures: 'β-quartz' and 'β-spodumene' type, respectively, and their parent glass have been studied. For the glass which does not contain 'non-bridging oxygen', a single mechanical relaxation peak linked with the stress-induced movement of lithium ions is observed. On the contrary, two peaks occur in the 'β-quartz' and 'β-spodumene' glass-ceramics. The 'low-temperature' peak (∼340 K for 1 Hz) is linked with ion mobility in the respective main crystalline phase. The origin of the 'high-temperature' peak is totally different for the two glass-ceramics; in the 'β-quartz' glass-ceramic, it is due to Mg2+ and Zn2+ ion relaxation in the crystalline phase, whereas in the 'β-spodumene' glass-ceramic, it is linked with a complex entity within the residual vitreous phase

  15. Mixed alkali effect in Li2O-Na2O-B2O3 glasses containing Fe2O3-An EPR and optical absorption study

    International Nuclear Information System (INIS)

    This paper reports the interesting results on mixed alkali effect (MAE) in xLi2O-(30-x)Na2O-69.5B2O3 (5 ≤ x ≤ 28) glasses containing Fe2O3 studied by electron paramagnetic resonance (EPR) and optical absorption techniques. The EPR spectra in these glasses exhibit three resonance signals at g = 7.60, 4.20 and 2.02. The resonance signal at g = 7.60 has been attributed to Fe3+ ions in axial symmetry sites whereas the resonance signal at g = 4.20 is due to isolated Fe3+ ions in rhombic symmetry site. The resonance signal at g = 2.02 is due to Fe3+ ions coupled by exchange interaction. It is interesting to observe that the number of spins participating in resonance (N) and its paramagnetic susceptibility (χ) exhibits the mixed alkali effect with composition. The present study also gives an indication that the size of alkali ions we choose in mixed alkali glasses is also an important contributing factor in showing the mixed alkali effect. It is observed that the variation of N with temperature obeys Boltzmann law. A linear relationship is observed between 1/χ and T in accordance with Curie-Weiss law. The paramagnetic Curie temperature (θ p) is negative for the investigated sample, which suggests that the iron ions are antiferromagnetically coupled by negative super exchange interactions at very low temperatures. The optical absorption spectra exhibit only one weak band corresponding to the transition 6A1g(S) →4A1g(G); 4Eg(G) at 446 nm which is a characteristic of Fe3+ ions in octahedral symmetry

  16. Analysis of H2O in silicate glass using attenuated total reflectance (ATR) micro-FTIR spectroscopy

    Science.gov (United States)

    Lowenstern, Jacob B.; Pitcher, Bradley W.

    2013-01-01

    We present a calibration for attenuated total reflectance (ATR) micro-FTIR for analysis of H2O in hydrous glass. A Ge ATR accessory was used to measure evanescent wave absorption by H2O within hydrous rhyolite and other standards. Absorbance at 3450 cm−1 (representing total H2O or H2Ot) and 1630 cm−1 (molecular H2O or H2Om) showed high correlation with measured H2O in the glasses as determined by transmission FTIR spectroscopy and manometry. For rhyolite, wt%H2O=245(±9)×A3450-0.22(±0.03) and wt%H2Om=235(±11)×A1630-0.20(±0.03) where A3450 and A1630 represent the ATR absorption at the relevant infrared wavelengths. The calibration permits determination of volatiles in singly polished glass samples with spot size down to ~5 μm (for H2O-rich samples) and detection limits of ~0.1 wt% H2O. Basaltic, basaltic andesite and dacitic glasses of known H2O concentrations fall along a density-adjusted calibration, indicating that ATR is relatively insensitive to glass composition, at least for calc-alkaline glasses. The following equation allows quantification of H2O in silicate glasses that range in composition from basalt to rhyolite: wt%H2O=(ω×A3450/ρ)+b where ω = 550 ± 21, b = −0.19 ± 0.03, ρ = density, in g/cm3, and A3450 is the ATR absorbance at 3450 cm−1. The ATR micro-FTIR technique is less sensitive than transmission FTIR, but requires only a singly polished sample for quantitative results, thus minimizing time for sample preparation. Compared with specular reflectance, it is more sensitive and better suited for imaging of H2O variations in heterogeneous samples such as melt inclusions. One drawback is that the technique can damage fragile samples and we therefore recommend mounting of unknowns in epoxy prior to polishing. Our calibration should hold for any Ge ATR crystals with the same incident angle (31°). Use of a different crystal type or geometry would require measurement of several H2O-bearing standards to provide a crystal

  17. High-efficiency ytterbium-free erbium-doped all-glass double cladding silicate glass fiber for resonantly-pumped fiber lasers.

    Science.gov (United States)

    Qiang, Zexuan; Geng, Jihong; Luo, Tao; Zhang, Jun; Jiang, Shibin

    2014-02-01

    A highly efficient ytterbium-free erbium-doped silicate glass fiber has been developed for high-power fiber laser applications at an eye-safe wavelength near 1.55 μm. Our preliminary experiments show that high laser efficiency can be obtained from a relatively short length of the gain fiber when resonantly pumped at 1535 nm in both core- and cladding-pumping configurations. With a core-pumping configuration as high as 75%, optical-to-optical efficiency and 4 W output power were obtained at 1560 nm from a 1 m long gain fiber. When using a cladding-pumping configuration, approximately 13 W output power with 67.7% slope efficiency was demonstrated from a piece of 2 m long fiber. The lengths of silicate-based gain fiber are much shorter than their silica-based counterparts used in other experiments, which is significantly important for high-power narrow-band and/or pulsed laser applications. PMID:24514181

  18. Physical properties and chemical durability of selected zirconia containing silicate glasses

    Directory of Open Access Journals (Sweden)

    ELEONÓRA GAŠPÁREKOVÁ

    2011-12-01

    Full Text Available Density, thermal expansion, glass transition temperature, refractive index, molar refractivity and chemical durability of five- and six-component glasses with as weighted composition xNa2O·(15-xK2O·yCaO∙(10-yZnO∙zZrO2∙(75-zSiO2 (x = 0, 7.5, 15; y = 0, 5, 10; z = 5, 7 were measured. The obtained experimental data were merged together with the previous results obtained for analogous glasses with lower zirconia content. The full set of glasses enabled the quantitative statistical estimation of possible mixed-oxide effects. The results of the multilinear regression analysis pointed out the ideal behavior of molar volume and molar refractivity. The strongest influence of mutual oxide interactions was found for chemical durability and glass transition temperature. The regression analysis of compositional dependence of metastable melt thermal expansion coefficient practically failed. The need of property-composition study based on the thermodynamic model was pointed out. Qualitatively the obtained results confirmed those previously obtained for the analogous glasses with zirconia content reaching up to 3 mol. %.

  19. Nanocrystal formation using laser irradiation on Nd3+ doped barium titanium silicate glasses

    International Nuclear Information System (INIS)

    Highlights: ► We compare two methods to produce glass–ceramic, furnace and laser irradiation. ► We study the spectroscopic properties of the glass ceramic created by both methods. ► A spectral mapping shows the area converted from glass to glass–ceramic by the laser. ► XRD, electronic microscopy and AFM confirm the spectral mapping conclusions. -- Abstract: Two different thermal treatments were used to create nanocrystals from a precursor glass. The glass whose composition is Ba2TiSi2O8 and doped with 3% of Nd3+ was prepared using the melt quenching method. A conventional thermal treatment in an electrical furnace was used to obtain transparent glass ceramic samples, which contain Fresnoite nanocrystals with an average size of 35 nm. Moreover, these nanocrystals were obtained in a localized area of the precursor glass by irradiating with a continuous Ar+ laser. Evidence of the changes induced by laser irradiation was confirmed by optical spectroscopic, X-ray diffraction, scanning electron and atomic force microscopy

  20. Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer

    Directory of Open Access Journals (Sweden)

    Liang Chen

    2016-09-01

    Full Text Available The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was found that the optimal geopolymer was prepared with metakaolin, sodium hydroxide, sodium silicate and water, with the molar ratio of SiO2:Al2O3:Na2O:NaOH:H2O being 3.4:1.1:0.5:1.0:11.8. X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FT-IR were adopted to investigate the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. The best curing condition was 60 °C for 168 h, and this alkali activated metakaolin-based geopolymer showed the highest compression strength at 52.26 MPa. In addition, hollow micro-sphere glass beads were mixed with metakaolin particles to improve the thermal insulation properties of the alkali activated metakaolin-based geopolymer. These results suggest that a suitable volume ratio of metakaolin to hollow micro-sphere glass beads in alkali activated metakaolin-based geopolymers was 6:1, which achieved a thermal conductivity of 0.37 W/mK and compressive strength of 50 MPa. By adjusting to a milder curing condition, as-prepared alkali activated metakaolin-based geopolymers could find widespread applications in concrete thermal protection.

  1. Influence of foaming agents on both the structure and the thermal conductivity of silicate glasses

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob;

    such as metal carbonates, or oxidizing transition metal oxides combined with carbonaceous sources. In this work, we mix CRT panel glass powder with different foaming agents: CaCO3 (0-4 wt%), Fe2O3 (0-6 wt%), and MnxOy (0-10 wt%). The powder mixtures are sintered in the range between the glass transition......Foam glass is one of the most promising insulation materials for constructions since it has low thermal conductivity, high compressive strength, non-water permeability, and high fire resistance. They can be produced using cullet sources, e.g., cathode ray tubes (CRT) panel glass, and foaming agents...... temperature (Tg) and the foaming temperature (corresponding to the viscosity range of 1012-106 Pa s) at 10 K/min and cool down to 773 K (below Tg) at 30 K/min and naturally down to room temperature. Upon sintering, the foaming agents are partially incorporated into the glass structure. Afterwards we measure...

  2. Effects of Aqueous Solutions on the Slow Crack Growth of Soda-Lime-Silicate Glass

    Science.gov (United States)

    Hausmann, Bronson D.; Salem, Jonathan A.

    2016-01-01

    The slow crack growth (SCG) parameters of soda-lime-silicate were measured in distilled and saltwater of various concentrations in order to determine if the presence of salt and the contaminate formation of a weak sodium film affects stress corrosion susceptibility. Past research indicates that solvents affect the rate of crack growth; however, the effects of salt have not been studied. The results indicate a small but statistically significant effect on the SCG parameters A and n at high concentrations; however, for typical engineering purposes, the effect can be ignored.

  3. Effect of Zn- and Ca-oxides on the structure and chemical durability of simulant alkali borosilicate glasses for immobilisation of UK high level wastes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hua, E-mail: nzhangh@aliyun.com [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom); China Institute of Atomic Energy, P.O. Box 275-93, 102413 Beijing (China); Corkhill, Claire L.; Heath, Paul G.; Hand, Russell J.; Stennett, Martin C. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom); Hyatt, Neil C., E-mail: n.c.hyatt@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2015-07-15

    Highlights: • Spinel crystallization incorporates ZnO from base glass, displacing Mg and Ni. • Raman spectroscopy demonstrates significant impact on glass structure by addition of ZnO to base glass. • Addition of ZnO reduces glass dissolution rate at early time periods (up to 28 days). - Abstract: Compositional modification of United Kingdom high level nuclear waste (HLW) glasses was investigated with the aim of understanding the impact of adopting a ZnO/CaO modified base glass on the vitrified product phase assemblage, glass structure, processing characteristics and dissolution kinetics. Crystalline spinel phases were identified in the vitrified products derived from the Na{sub 2}O/Li{sub 2}O and the ZnO/CaO modified base glass compositions; the volume fraction of the spinel crystallites increased with increasing waste loading from 15 to 20 wt%. The spinel composition was influenced by the base glass components; in the vitrified product obtained with the ZnO/CaO modified base glass, the spinel phase contained a greater proportion of Zn, with a nominal composition of (Zn{sub 0.60}Ni{sub 0.20}Mg{sub 0.20})(Cr{sub 1.37}Fe{sub 0.63})O{sub 4}. The addition of ZnO and CaO to the base glass was also found to significantly alter the glass structure, with changes identified in both borate and silicate glass networks using Raman spectroscopy. In particular, these glasses were characterised by a significantly higher Q{sup 3} species, which we attribute to Si–O–Zn linkages; addition of ZnO and CaO to the glass composition therefore enhanced glass network polymerisation. The increase in network polymerisation, and the presence of spinel crystallites, were found to increase the glass viscosity of the ZnO/CaO modified base glass; however, the viscosities were within the accepted range for nuclear waste glass processing. The ZnO/CaO modified glass compositions were observed to be significantly more durable than the Na{sub 2}O/Li{sub 2}O base glass up to 28 days, due to

  4. Visible light activated catalytic effect of iron containing soda-lime silicate glass characterized by 57Fe-Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    A relationship between local structure and visible light activated catalytic effect of iron containing soda lime silicate glass with the composition of 15Na2O·15CaO·xFe2O3·(70-x)SiO2, x = 5-50 mass %, abbreviated as NCFSx was investigated by means of 57Fe-Moessbauer spectroscopy, X-ray diffractometry (XRD), small angle X-ray scattering (SAXS), electrospray ionization mass spectrometry (ESI-MS) and ultraviolet-visible light absorption spectroscopy (UV-Vis). Moessbauer spectra of NCFSx glass with 'x' being equal to or larger than 30 after isothermal annealing at 1,000 deg C for 100 min consisted of a paramagnetic doublet and a magnetic sextet. The former had isomer shift (δ) of 0.24 mm s-1 and quadrupole splitting (Δ) of 0.99 mm s-1 due to distorted FeIIIO4 tetrahedra, and the latter had δ of 0.36 mm s-1 and internal magnetic field (Hint) of 51.8 T due to hematite (α-Fe2O3). The absorption area (A) of α-Fe2O3 varied from 47.2 to 75.9, 93.1, 64.8 and 47.9 % with 'x' from 30 to 35, 40, 45 and 50, indicating that the amount of precipitated α-Fe2O3 varied with the Fe2O3 content of NCFSx glass. The precipitation of α-Fe2O3 was also confirmed by XRD study of annealed NCFS glass with 'x' larger than 30. A relaxed sexted with δ, Hint and Γ of 0.34 mm s-1 and 37.9 T and 1.32 mm s-1 was observed from the Moessbauer spectra of annealed NCFSx glass with 'x' of 45 and 50, implying that the precipitation of non-stoichiometric iron hydroxide oxide with the composition of Fe1.833(OH)0.5O2.5 having the similar structure of α-Fe2O3 and α-FeOOH. A remarkable decrease in the concentration of methylene blue (MB) from 10 to 0.0 μmol L-1 with the first-order rate constant (k) of 2.87 × 10-2 h-1 was observed for 10-day leaching test using annealed NCFS50 glass under visible light irradiation. ESI-MS study indicated that existence of fragments with m/z value of 129, 117 and 207 etc. originating from MB having m/z of 284. This result evidently showed that the MB concentration

  5. The Compositional Variation of Microindentation Induced Densified and Plastic Deformation Volumes in Simple Silicate Glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian; Matsuoka, Jun; Yoshida, Satoshi;

    2012-01-01

    The densification and plastic deformation occurring in glass subjected to microindentation are established as two independent deformation mechanisms, and thought to be intimately linked to the concept of hardness and crack nucleation (quantified by the load at which radial cracks nucleate at half...... the corners of a Vickers pyramid indent.) These two properties are commercially important as they correlate with e.g. resistance to surface damage and the ultimate strength of glass, yet little is known of their variation with glass composition. In the present work, we determine the densified and plastically...... credence to the empirical correlation between hardness and elastic moduli. The plastic deformation volume was not measurable up to a modifying oxide fraction of 20%, but was found to increase linearly with this fraction above 20%. As the plastically induced stress is thought to be the cause of radial...

  6. Surface signatures of bioactivity: MD simulations of 45S and 65S silicate glasses.

    Science.gov (United States)

    Tilocca, Antonio; Cormack, Alastair N

    2010-01-01

    The surface of a bioactive (45S) and a bioinactive (65S) glass composition has been modeled using shell-model classical molecular dynamics simulations. Direct comparison of the two structures allowed us to identify the potential role of specific surface features in the processes leading to integration of a bioglass implant with the host tissues, focusing in particular on the initial dissolution of the glass network. The simulations highlight the critical role of network fragmentation and sodium enrichment of the surface in determining the rapid hydrolysis and release of silica fragments in solution, characteristic of highly bioactive compositions. On the other hand, no correlation has been found between the surface density of small (two- and three-membered) rings and bioactivity, thus suggesting that additional factors need to be taken into account to fully understand the role of these sites in the mechanism leading to calcium phosphate deposition on the glass surface. PMID:19725567

  7. Spectral properties of erbium-doped heavy metal oxyfluoride silicate glasses for broadband amplification

    Institute of Scientific and Technical Information of China (English)

    徐时清; 杨中民; 戴世勋; 杨建虎; 戴能利; 林傲翔; 胡丽丽; 姜中宏

    2003-01-01

    Erbium-doped glasses showing a wide 1.55?m emission band are reported ina novel heavy metal oxyfluoride glass system SiO2-PbO-PbF2 and their optical properties such as emission spectra,fluorescence lifetime and the refractive index have been investigated.The broad and flat 4I13/2 →4I15/2 emission of Er3+ ions around 1.55μm can be used as host materials for potential optical amplifiers in wavelength-division-multiplexing network system.We find that with increasing PbF2 content in the glass composition,the fluorescence full width at half maximum and fluorescence lifetime of the 4I13/2 level of Er3+ increase,while refractive index and density decrease.

  8. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-08-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  9. Effect of Ti(+4) on in vitro bioactivity and antibacterial activity of silicate glass-ceramics.

    Science.gov (United States)

    Riaz, Madeeha; Zia, Rehana; Saleemi, Farhat; Hussain, Tousif; Bashir, Farooq; Ikhram, Hafeez

    2016-12-01

    A novel glass-ceramic series in (48-x) SiO2-36 CaO-4 P2O5-12 Na2O-xTiO2 (where x=0, 3.5, 7, 10.5 and 14mol %) system was synthesized by crystallization of glass powders, obtained by melt quenching technique. The differential scanning calorimetric analysis (DSC) was used to study the non-isothermal crystallization kinetics of the as prepared glasses. The crystallization behaviour of glasses was analyzed under non-isothermal conditions, and qualitative phase analysis of glass-ceramics was made by X-ray diffraction. The in vitro bioactivity of synthesized glass-ceramics was studied in stimulated body fluid at 37°C under static condition for 24days. The formation of hydroxyl-carbonated apatite layer; evident of bioactivity of the material, was elucidated by XRD, FTIR, AAS, SEM and EDX analysis. The result showed that partial substitution of TiO2 with SiO2 negatively influenced bioactivity; it decreased with increase in concentration of TiO2. As Ti(+4) having stronger field strength as compared to Si(+4) so its replacement became the cause for reduction in degradation that in turn improved the chemical stability. The compressive strength was also enhanced with progress addition of TiO2 in the system. The antibacterial properties were examined against Staphylococcus Epidermidis. Strong antibacterial efficacy was observed with the addition of TiO2 in the system. PMID:27612803

  10. The Durability and Performance of Short Fibers for a Newly Developed Alkali-Activated Binder

    Directory of Open Access Journals (Sweden)

    Henrik Funke

    2016-03-01

    Full Text Available This study reports the development of a fiber-reinforced alkali-activated binder (FRAAB with an emphasis on the performance and the durability of the fibers in the alkaline alkali-activated binder (AAB-matrix. For the development of the matrix, the reactive components granulated slag and coal fly ash were used, which were alkali-activated with a mixture of sodium hydroxide (2–10 mol/L and an aqueous sodium silicate solution (SiO2/Na2O molar ratio: 2.1 at ambient temperature. For the reinforcement of the matrix integral fibers of alkali-resistant glass (AR-glass, E-glass, basalt, and carbon with a fiber volume content of 0.5% were used. By the integration of these short fibers, the three-point bending tensile strength of the AAB increased strikingly from 4.6 MPa (no fibers up to 5.7 MPa (carbon after one day. As a result of the investigations of the alkali resistance, the AR-glass and the carbon fibers showed the highest durability of all fibers in the FRAAB-matrix. In contrast to that, the weight loss of E-glass and basalt fibers was significant under the alkaline condition. According to these results, only the AR-glass and the carbon fibers reveal sufficient durability in the alkaline AAB-matrix.

  11. Effect of halides addition on the ligand field of chromium in alkali borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, M.A., E-mail: moukhtar_hassan@yahoo.com

    2013-10-15

    Highlights: •The 10 KM–64.7 B{sub 2}O{sub 3}–25 Na{sub 2}O–0.3 Cr{sub 2}O{sub 3} (M = Cl, Br and I) glassy system was prepared by a quenching method. •Optical basicity, ligand field theory optical band gap energy, refractive index, ESR and IR were studied. •The electronegativity plays an important role in deforming the crystal field around the transition metal ions. •The crystal-field sites of KCl or KBr sample are very strong compared to the very weak one in the KI sample. -- Abstract: Borate oxide glass system of composition 10 KM–64.7 B{sub 2}O{sub 3}–25 Na{sub 2}O–0.3 Cr{sub 2}O{sub 3} (M = Cl, Br and I) was prepared by conventional melt quenching technique. The amorphous nature of the investigated glasses was checked by the X-ray diffraction (XRD) technique. The optical basicity of the system has been calculated, and was found to increase by going from KCl to KBr and to KI. Optical absorption spectra were recorded in the UV–visible range. Through a careful analysis of the data, the ligand field parameters (crystal field strength Dq, Racah parameters B and nephelauxetic functions h) and the optical parameters (optical band gap, Urbach tail band width, and refractive index) have been estimated. The obtained results reveal a strong correlation between that ligand field parameters and the type of halogen atom; the crystal-field strength of KCl or KBr samples are very pronounced but it is rather weak in the KI sample. Electron spin resonance (ESR) has been used to probe the valency of the Chromium ions. The resulting ESR parameters revealed that chromium ions are predominantly in the trivalent state with traces of hexavalent state. Using Infrared spectroscopy (IR) information on the boron structural units has been obtained. The N{sub 4} ratio increases by replacing the KCl by KBr or KI, and it was found that the tetrahedral coordination of Cr{sup +} ions becomes preferential in the host glasses with increasing the optical basicity.

  12. Preliminary study of window silicate glass powder for EPR dosimetry with 10-MeV electron beam irradiation

    International Nuclear Information System (INIS)

    Window silicate glass powder has been evaluated as a possible high dose dosimeter using EPR (Electron Paramagnetic Resonance) technique. In this work window glass powder with maximum dimension of 700 μm was irradiated with 10 MeV electrons with doses ranging from 580 Gy to 46.52 kGy. The EPR response of the irradiated samples showed a linear behavior to applied doses up to 8 kGy. The EPR spectra of NBOHC (Non-Bonding Oxygen Hole Center) was found at g1 = 2.0092 ± 0.0001 and g2 = 2.0042 ± 0.0001. The line widths of all spectra were found to be the same. Finally, the thermal fading of EPR intensity was studied for 70 days and showed a sharp decline on the first day. This fading continued up to almost 15 days and then the slope of the decay-curve tended to gradual changes up to 50 days. Afterwards, it presented a fairly constant value with time and a predictable stability was achieved.

  13. A dynamic fatigue study of soda-lime silicate and borosilicate glasses using small scale indentation flaws

    International Nuclear Information System (INIS)

    The dynamic fatigue characteristics of two glasses, soda-lime silicate and borosilicate, in water have been studied using a controlled indentation flaw technique. It is argued that the indentation approach offers several advantages over more conventional fatigue testing procedures: (i) the reproducibility of data is relatively high, eliminating statistics as a basis of analysis: (ii) the flaw ultimately responsible for failure is well defined and may be conveniently characterised before and after (and during, if necessary) the strength test; (iii) via adjustment of the indentation load, the size of the flaw can be suitably predetermined. Particular attention is devoted to the third point because of the facility it provides for systematic investigation of the range of flaw sizes over which macroscopic crack behaviour remains applicable. The first part of the paper summarises the essential fracture mechanics theory of the extension of an indentation flaw to failure. In the next part of the paper the results of dynamic fatigue tests on glass rods in distilled water are described. Data are obtained for Vickers indentation loads in the range 0.05 to 100 N, corresponding to contact dimensions of 2 to 100 μm. Finally, the implications of the results in relation to the response of 'natural' flaws are discussed. (author)

  14. Structure and aqueous reactivity of silicate glasses high-resolution nuclear magnetic resonance contribution; Structure et reactivite aqueuse des verres silicates apport de la resonance magnetique nucleaire haute-resolution

    Energy Technology Data Exchange (ETDEWEB)

    Angeli, F

    2000-10-25

    This research aims at getting a better understanding of the relations which may exist between the chemical composition of the oxide silicate glasses, the structure and the aqueous reactivity. We study the cations present in most glasses, more particularly the radioactive waste glasses, and those which are more liable to bring information both about structure and reactivity. Among the experimental methods used, the nuclear magnetic resonance of multi-quantum magic-angle spinning (NMR MQ-MAS) has been carried out for the structural characterization of the pristine and altered glasses. In the first part, we discuss the possibility of deducting a type of information from a quantitative approach of the {sup 23}Na, {sup 27}Al and {sup 17}O NMR MQ-MAS. In the second part, we apply this method to glasses containing between two and six oxides. The vitreous compositions studied permit to focus our attention on the influence of sodium, aluminum and calcium on their local structural environment. We point out an evolution of the distributions of bond distances and angles in relation to the glass chemical composition. We show the strong potentiality of the {sup 17}O used to probe the pristine and altered glasses. The influence of the different cations studied on the rate of glass dissolution is debated from the alterations made on short periods. On the basis of all these data, we discuss the importance of the structural effect which may influence the kinetic phenomena of alteration. (author)

  15. A study on fluorescence properties of Eu~(3+) ions in alkali lead tellurofluoroborate glasses

    Institute of Scientific and Technical Information of China (English)

    S.A.Saleem; B.C.Jamalaiah; A.Mohan; Babu; K.Pavani; L.R

    2010-01-01

    Glasses with chemical composition of (in mol.%): 26 RF-20 PbO-10 TeO2-43 H3BO3-1 EuO3 (RLTB) were prepared by conventional melt quenching method. The Judd-Ofelt intensity parameters Ω2 and Ω6 were obtained from the absorption intensities of 7F0→5D2 and 7F0→5L6 transitions, respectively. In order to overcome the problem of applicability of Judd-Ofelt analysis at room temperature due to the overlapping of the transitions originating from 7F0 and 7F1 levels of Eu3+ ion, the effect of the thermalization on the ...

  16. Composition dependence of luminescence of Eu and Eu/Tb doped silicate glasses for LED applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Chaussedent, S.; Liu, S.;

    2013-01-01

    . The variation of the excitation wavelength can tune the emission spectra as well as Commission Internationale de L’Eclairage (CIE) chromaticity coordinates of Eu/Tb co-doped glasses for specific applications. The energy transfer from Tb3+ to Eu3+ ions is investigated by analyzing fluorescence spectra and decay...... such as B2O3, Al2O3 and CaF2 on the luminescent properties of the above-mentioned glasses. We explore the role of Eu3+ ions as a structural probe of the glasses by determining the asymmetry factor, i.e., the ratio of the emission intensity of the 5D0→7F2 transition to that of the 5D0 →7F1 transition....... The results show that the asymmetry factor and luminescence lifetimes of as-prepared materials are dependent on composition. White fluorescence is achieved in Eu/Tb co-doped glasses, which can be attributed to the simultaneous generation of red, green and blue wavelengths from Eu3+ and Tb3+ ions...

  17. Self-diffusion of oxygen in soda-lime silicate glass

    International Nuclear Information System (INIS)

    The self-diffusion coefficients of oxygen in 16Na2O x 12CaO x 72SiO2 glass were measured in the temperature range from 500 to 1,4700C by means of an isotope exchange technique employing 18O as the tracer. The results in the temperature range over 8000C were represented by D = 4.5 x 10-2 exp(-38.6 x 103/RT). This activation energy for diffusion was in good agreement with that for viscous flow of the glass. The relationship between the oxygen self-diffusion coefficient and the viscosity was satisfactorily described by Eyring's equation rather than the Stokes-Einstein relation. The measured oxygen self-diffusion coefficients also showed agreements with the diffusion coefficients calculated from an interdiffusion kinetics and from the dissolution rate of a quartz glass in the glass melt, which indicated that these processes were governed by the diffusion of oxygen ions. The steep temperature dependence of the oxygen self-diffusion coefficient which was determined in the transition range was explained to be due to an excess structural activation energy required for migration of oxygen ions. (orig.)

  18. Effect of additive ions on the optical density and stability of the color centers induced by X-ray irradiation in soda-lime silicate glass

    International Nuclear Information System (INIS)

    To apply radiation-induced coloration of glasses as a reversible glass-coloring technique, we studied the influence of various additive ions incorporated into a soda-lime silicate glass on the optical density and stability of the color induced by X-ray irradiation. Absorption spectra before and after irradiation are discussed in the comparison with those of the undoped soda-lime silicate glass. Additive ions were incorporated as metal oxides, namely TiO2, V2O5, Fe2O3, ZnO, Ga2O3, GeO2, ZrO2, Nb2O3, MoO3, Ag2O, In2O3, SnO, SnO2, CeO2, Eu2O3, Ta2O5, WO3 and Bi2O3. Among them, TiO2, GeO2, Nb2O3, MoO3, Ag2O, In2O3, Eu2O3, Ta2O5, WO3 and Bi2O3 have a large effect on optical density. The optical densities in the visible region for glasses doped with these oxides were much stronger than for undoped soda-lime silicate glass. On the other hand, incorporation of Fe2O3, SnO and CeO2 reduced the optical density. Over longer periods the coloration of the undoped glass was one of the most stable while those of the Fe2O3, SnO and CeO2-doped glasses soon faded.

  19. Mineralogy of silicate inclusions of the Colomera IIE iron and crystallization of Cr-diopside and alkali feldspar from a partial melt

    Science.gov (United States)

    Takeda, Hiroshi; Hsu, Weibiao; Huss, Gary R.

    2003-06-01

    We studied the mineralogy, mineral chemistry, and compositions of 48 interior silicate inclusions and a large K-rich surface inclusion from the Colomera IIE iron meteorite. Common minerals in the interior silicate inclusions are Cr diopside and Na plagioclase (albite). They are often enclosed by or coexist with albitic glasses with excess silica and minor Fe-Mg components. This mineral assemblage is similar to the "andesitic" material found in the Caddo County IAB iron meteorite for which a partial melt origin has been proposed. The fairly uniform compositions of Cr diopside (Ca 44Mg 46Fe 10) and Na plagioclase (Or 2.5Ab 90.0An 7.5 to Or 3.5Ab 96.1An 0.4) in Colomera interior inclusions and the angular boundaries between minerals and metal suggest that diopside and plagioclase partially crystallized under near-equilibrium conditions from a common melt before emplacement into molten metal. The melt-crystal assemblage has been called "crystal mush." The bulk compositions of the individual composite inclusions form an array between the most diopside-rich inclusion and plagioclase. This is consistent only with a simple mechanical mixing relationship, not a magmatic evolution series. We propose a model in which partly molten metal and crystal mush were mixed together by impact on the IIE parent body. Other models involving impact melting of the chondritic source material followed by growth of diopside and plagioclase do not easily explain near equilibrium growth of diopside and Na plagioclase, followed by rapid cooling. In the K-rich surface inclusion, K feldspar, orthopyroxene, and olivine were found together with diopside for the first time. K feldspar (sanidine, Or 92.7Ab 7.2An 0.1 to Or 87.3Ab 11.0An 1.7) occurs in an irregular veinlike region in contact with large orthopyroxene crystals of nearly uniform composition (Ca 1.3Mg 80.5Fe 17.8 to Ca 3.1Mg 78.1Fe 18.9) and intruding into a relict olivine with deformed-oval shape. Silica and subrounded Cr diopside are

  20. Utilization of Mineral Wools as Alkali-Activated Material Precursor

    Directory of Open Access Journals (Sweden)

    Juho Yliniemi

    2016-04-01

    Full Text Available Mineral wools are the most common insulation materials in buildings worldwide. However, mineral wool waste is often considered unrecyclable because of its fibrous nature and low density. In this paper, rock wool (RW and glass wool (GW were studied as alkali-activated material precursors without any additional co-binders. Both mineral wools were pulverized by a vibratory disc mill in order to remove the fibrous nature of the material. The pulverized mineral wools were then alkali-activated with a sodium aluminate solution. Compressive strengths of up to 30.0 MPa and 48.7 MPa were measured for RW and GW, respectively, with high flexural strengths measured for both (20.1 MPa for RW and 13.2 MPa for GW. The resulting alkali-activated matrix was a composite-type in which partly-dissolved fibers were dispersed. In addition to the amorphous material, sodium aluminate silicate hydroxide hydrate and magnesium aluminum hydroxide carbonate phases were identified in the alkali-activated RW samples. The only crystalline phase in the GW samples was sodium aluminum silicate. The results of this study show that mineral wool is a very promising raw material for alkali activation.

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

    Science.gov (United States)

    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.

  2. On the Paramagnetic Impurity Concentration of Silicate Glasses from Low-Temperature Physics

    Science.gov (United States)

    Bonfanti, Silvia; Jug, Giancarlo

    2015-08-01

    The concentration of paramagnetic trace impurities in glasses can be determined via precise SQUID measurements of the sample's magnetization in a magnetic field. However, the existence of quasi-ordered structural inhomogeneities in the disordered solid causes correlated tunneling currents that can contribute to the magnetization, surprisingly, also at the higher temperatures. We show that taking into account such tunneling systems gives rise to a good agreement between the concentrations extracted from SQUID magnetization and those extracted from low-temperature heat capacity measurements. Without suitable inclusion of such magnetization contribution from the tunneling currents, we find that the concentration of paramagnetic impurities gets considerably over-estimated. This analysis represents a further positive test for the structural inhomogeneity theory of the magnetic effects in the cold glasses.

  3. Role of elastic deformation in determining the mixed alkaline earth effect of hardness in silicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Potuzak, M.;

    2015-01-01

    show that the mixed alkaline earth effect manifests itself as deviations from linearity in shear modulus, Poisson’s ratio, glass transition temperature, liquid fragility index, hardness, volume of densification, and volume of plastic flow. We find no correlation between the elastic part...... of the indentation and hardness, and we thus infer that elastic deformation does not play a dominant role in determining the mixed alkaline earth effect of hardness. However, interestingly, we find a strong correlation between Poisson’s ratio, volume of plastic flow, and hardness, by which the minimum in hardness......Glasses deform permanently as a result of indentation and the total resistance to deformation consists of three individual resistances, i.e., those to elastic deformation, densification, and plastic flow. The link between Vickers hardness and the resistances to densification and plastic flow has...

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

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Hiroshi; Sakai, Daisuke; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Hokkaido 001-0020 (Japan); Funatsu, Shiro [Production Technology Center, Asahi Glass Co., Ltd., 1-1 Suehiro-cyo, Tsurumiku, Yokohama, Kanagawa 230-0045 (Japan); Yamamoto, Kiyoshi; Suzuki, Toshio [Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama, Kanagawa 221-8755 (Japan); Harada, Kenji [Department of Computer Science, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan)

    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.

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

    Science.gov (United States)

    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.

  6. Color center generation in sodium-calcium silicate glass by nanosecond and femtosecond laser pulses

    Science.gov (United States)

    Siiman, Leo A.; Glebov, Leonid B.

    2005-12-01

    It was found that high purity soda lime glass shows a markedly different induced absorption spectra when exposed to different types of ionizing radiation such as UV lamp or femtosecond and nanosecond laser pulses. The following irradiation was used in the experiments: nanosecond pulses at the fundamental and harmonics of a Nd:YAG laser (λ = 1064, 532, 355, and 266 nm), femtosecond pulses of a Ti:sapphire laser operating at λ = 780 nm, ultraviolet rays from a high pressure Xe lamp, X-rays, and Gamma rays. Features of radiation defect generations are discussed.

  7. Small angle X-ray and neutron scattering on cadmium sulfide nanoparticles in silicate glass

    Science.gov (United States)

    Kuznetsova, Yu. V.; Rempel, A. A.; Meyer, M.; Pipich, V.; Gerth, S.; Magerl, A.

    2016-08-01

    Small angle X-ray and neutron scattering on Cd and S doped glass annealed at 600 °C shows after the first 12 h nucleation and growth of spherical CdS nanoparticles with a radius of up to 34±4 Å. After the nucleation is completed after 24 h, further growth in this amorphous environment is governed by oriented particle attachment mechanism as found for a liquid medium. Towards 48 h the particle shape has changed into spheroidal with short and long axis of 40±2 Å and 120±2 Å, respectively.

  8. Ultrafast dynamics of copper nanoparticles embedded in soda-lime silicate glass fabricated by ion exchange

    International Nuclear Information System (INIS)

    Copper nanoparticles embedded in soda-lime glass were fabricated by ion exchange followed by thermal treatment in hydrogen. The ultrafast dynamics of the embedded Cu nanoparticles formed under different fabrication conditions were investigated by applying femtosecond pump-probe technique. Non-Fermi electrons were suggested to be dominant in the transient behavior of the nanocomposites far from surface plasmon resonance of Cu. The long ion-exchange processing time was found to benefit and improve the ultrafast response of the fabricated nanocomposites.

  9. Moessbauer analysis of crystallization processes in iron-soda-lime-silicate glasses

    International Nuclear Information System (INIS)

    57Fe Moessbauer spectroscopy was used to observe the crystallization process in glasses with composition denoted by [0.50SiO2, 0.45Na2O, 0.05CaO]100-x(Fe2O3)x with x equal to 4, 10 and 16 mol%. It is shown that Moessbauer spectroscopy is a very suitable technique for detecting and checking the very early stages of crystallite formation in amorphous materials. The crystallization process was observed and qualitatively analysed by means of classical volume nucleation theory

  10. Time-resolved luminescence studies of Eu3+ in soda-lime silicate glasses

    Science.gov (United States)

    Ruivo, Andreia; Muralha, Vânia S. F.; Águas, Hugo; de Matos, António Pires; Laia, César A. T.

    2014-02-01

    Soda-lime glasses doped with Eu3+ were synthesized using a variety of compositions, namely changing the fraction of CaO or Eu2O3. Those glasses were characterized with several techniques, including ellipsometry, UV-vis-NIR absorption spectroscopy, steady-state photoluminescence spectroscopy and time-resolved luminescence. The compositions' effects on optical properties such as refraction indexes, Eu3+ oscillator strengths and luminescence lifetimes were accessed from the analysis of the experimental results. Judd-Ofelt theory was used to analyze all these aspects, which allow the detection of a mismatch of optical properties from absorption and emission spectroscopy. This mismatch was confirmed from the time-resolved data, showing the existence of two different spectroscopic Eu3+ species. From those results it is concluded that there is evidence for lanthanide aggregation, giving rise to self-quenching effects that may be described through resonance energy transfer mechanisms. The difference between luminescence lifetimes for isolated and aggregated Eu(III) is interpreted as due to different interactions with oxygen in the matrix, namely degree of covalency of the Eu-O bond and point group symmetry of the lanthanide.

  11. Radiation-Induced Centers in Lead Silicate Glasses Irradiated by Stationary and Pulsed Electron Beams

    Science.gov (United States)

    Zhidkov, I. S.; Zatsepin, A. F.; Konev, S. F.; Cholakh, S. O.

    2015-08-01

    Radiation-induced centers formed in heavy flint glasses irradiated by electron beams are investigated by the methods of optical and EPR spectroscopy. It is revealed that stable and short-living optical absorption centers of close natures are formed under irradiation by fast electrons. A correlation is established between the stable optical absorption bands and the EPR signals interpreted as signals of the (Pb2+)/h+ hole centers. The shortliving color centers are formed due to short-term distortion of the O-Pb bonds, and the stable centers are formed due to the spatial separation, thermalization, and subsequent stabilization of excited electrons and holes in tails of the localized states. Irradiation by electron beams leads to a change in the spectral characteristics of the fundamental absorption edge and, in particular, of the Urbach energy that determines the degree of structural disorder.

  12. The behavior of Er3+ dopants during crystallization in oxyfluoride silicate glass ceramics

    International Nuclear Information System (INIS)

    In this paper, the changes of local environment of Er3+ during heat treatment process have been studied in 50SiO2-45PbF2-5PbO system. The samples were characterized by X-ray diffraction (XRD), absorption spectra, fluorescence decay curves and luminescence spectra. The experimental results indicate that PbF2 crystals were precipitated in the precursor sample. However, a significant fraction of Er3+ remains in the glassy phase. With increasing heat treatment time, the Er3+ in the glass matrix may enter into fluoride nanocrystals gradually. When the heat treatment time reached 15 min, most of the Er3+ ions were incorporated into the fluoride nanocrystals. Based on the experimental analysis, we considered that Er3+ not only act as nucleating agents for the precipitation of crystalline fluoride phase during nucleation process but also enter into nanocrystals during crystals growth process.

  13. Formation of Na1+xV3O8 Nanoribbon Thin Film from V2O5 Xerogel on Sodium Silicate Glass Substrate

    Institute of Scientific and Technical Information of China (English)

    GUO Yi; XU Jin-jie; LI Jun; YANG Wen-sheng

    2007-01-01

    Na1+xV3O8 nanoribbon thin film was successfully fabricated by annealing the V2O5 xerogel film on sodium silicate glass substrate at 450 ℃. It has been identified that the amount of sodium ions diffused into the V2O5 xerogel film increases with the high temperature of annealing treatment. The sodium glass substrate serves as a limited sodium source to induce the transformation from V2O5 to Na1+xV3O8.

  14. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    OpenAIRE

    Farah, Khaled; Hosni, Faouzi; Mejri, Arbi; Boizot, Bruno; Hafedh, Ben; Hamzaoui, Ahmed Hichem

    2014-01-01

    International audience Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO 3 and NaNO 3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the s...

  15. Enamel and Dentin Surface Finishing Influence on the Roughness and Microshear Bond Strength of a Lithium Silicate Glass-Ceramic for Laminate Veneers

    OpenAIRE

    Gonzaga, Carla Castiglia; Bravo, Ruth Peggy; Pavelski, Thiago Vinícius; Garcia, Paula Pontes; Gisele Maria CORRER; Leonardi, Denise Piotto; Cunha, Leonardo Fernandes da; Adilson Yoshio FURUSE

    2015-01-01

    Objectives. This study evaluated the influence of cavity surface finishing with diamond burs of different grit mounted on high-speed turbine and ultrasound on the roughness and microshear bond strength (MBS) of a lithium silicate glass-ceramic to enamel and dentin. Methods. Enamel and dentin specimens were divided into seven groups, according to the type of surface finishing: 1200-grit sandpaper (control), two different brands of medium-grit and fine-grit diamond burs in a high-speed turbine;...

  16. The behavior of Er{sup 3+} dopants during crystallization in oxyfluoride silicate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lin Lejing [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China); Ren Guozhong, E-mail: rgz76@sohu.co [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China); Chen Minpeng; Liu Yang [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China)

    2009-11-03

    In this paper, the changes of local environment of Er{sup 3+} during heat treatment process have been studied in 50SiO{sub 2}-45PbF{sub 2}-5PbO system. The samples were characterized by X-ray diffraction (XRD), absorption spectra, fluorescence decay curves and luminescence spectra. The experimental results indicate that PbF{sub 2} crystals were precipitated in the precursor sample. However, a significant fraction of Er{sup 3+} remains in the glassy phase. With increasing heat treatment time, the Er{sup 3+} in the glass matrix may enter into fluoride nanocrystals gradually. When the heat treatment time reached 15 min, most of the Er{sup 3+} ions were incorporated into the fluoride nanocrystals. Based on the experimental analysis, we considered that Er{sup 3+} not only act as nucleating agents for the precipitation of crystalline fluoride phase during nucleation process but also enter into nanocrystals during crystals growth process.

  17. A study on microstructure and luminescent properties of oxyfluoride silicate glass-ceramics with (Ho3+,Yb3+):NaYF4 crystallites

    International Nuclear Information System (INIS)

    Highlights: → Oxyfluoride glass-ceramic with NaYF4 nanocrystals content the Ho3+ and Yb3+ ions. → Up-converted green emission in glass-ceramics was observed. → Up-converted red emission occurs in glass samples. → Appropriate up-conversion mechanism is proposed. - Abstract: Glass-ceramics containing NaYF4 nanocrystals were prepared by heat-treatment from oxyfluoride silicate-based glass doped with Ho3+ and Yb3+ ions. The formation of crystalline fluoride phase was confirmed by X-ray diffraction and transmission electron microscopy. Absorption and emission spectra revealed that a fraction of Ho3+ and Yb3+ ions is incorporated into the NaYF4 ordered lattice influencing spectroscopic features of glass-ceramics in comparison with those of precursor glass. Green up-conversion emission (545 nm) originating in the 5S2 level in glass-ceramics and up-converted red emission (650 nm) originating in the 5F5 level in as-melted glass were observed under optical pumping into Yb3+ absorption band and analyzed. Although both emissions in both materials are achieved by two-photon excitations, the relation between green and red emission intensity in glass-ceramics and glass implies that processes relevant to up-conversion phenomena are different. Based on a careful analysis of relaxation dynamics of Ho3+ and Yb3+ excited states, the mechanisms involved in conversion of the infrared radiation into the visible emission in these materials are proposed and discussed.

  18. A study on microstructure and luminescent properties of oxyfluoride silicate glass-ceramics with (Ho{sup 3+},Yb{sup 3+}):NaYF{sub 4} crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Dominiak-Dzik, G., E-mail: G.Dominiak-Dzik@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-950 Wroclaw (Poland); Lisiecki, R.; Ryba-Romanowski, W.; Krajczyk, L. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-950 Wroclaw (Poland)

    2012-01-15

    Highlights: > Oxyfluoride glass-ceramic with NaYF{sub 4} nanocrystals content the Ho{sup 3+} and Yb{sup 3+} ions. > Up-converted green emission in glass-ceramics was observed. > Up-converted red emission occurs in glass samples. > Appropriate up-conversion mechanism is proposed. - Abstract: Glass-ceramics containing NaYF{sub 4} nanocrystals were prepared by heat-treatment from oxyfluoride silicate-based glass doped with Ho{sup 3+} and Yb{sup 3+} ions. The formation of crystalline fluoride phase was confirmed by X-ray diffraction and transmission electron microscopy. Absorption and emission spectra revealed that a fraction of Ho{sup 3+} and Yb{sup 3+} ions is incorporated into the NaYF{sub 4} ordered lattice influencing spectroscopic features of glass-ceramics in comparison with those of precursor glass. Green up-conversion emission (545 nm) originating in the {sup 5}S{sub 2} level in glass-ceramics and up-converted red emission (650 nm) originating in the {sup 5}F{sub 5} level in as-melted glass were observed under optical pumping into Yb{sup 3+} absorption band and analyzed. Although both emissions in both materials are achieved by two-photon excitations, the relation between green and red emission intensity in glass-ceramics and glass implies that processes relevant to up-conversion phenomena are different. Based on a careful analysis of relaxation dynamics of Ho{sup 3+} and Yb{sup 3+} excited states, the mechanisms involved in conversion of the infrared radiation into the visible emission in these materials are proposed and discussed.

  19. 高压电场对钠钙硅酸盐玻璃风化性能的影响%Influences of the Imposed High Voltage Electric Field on the Weathering Properties of Soda-lime Silicate Glass

    Institute of Scientific and Technical Information of China (English)

    王洪成; 刘启明

    2009-01-01

    The soda-lime silicate float gIass is imposed to high voltage electrostatic field at the annealing temperature range of the ghss.The in fluences of the leakage current intensity,processing temperature and time on the ehnical stabilityofgLassan.der high-voltage electrostatic field are researched.The use of chemical titration analysis tested alkali of glass surface to research the hydrolytic resistance of glass.The glass samples accelerated weathering tests are carried out using constant temperature and humidity chamber,and the glass microscope morphology after weathering is observed by metallographic microscope XJZ-6.The experimental results show that when leakage current strength is lower than l50μA/cm~2,with increase of the high voltage elec trostatic field,the chemical stability(hydrolytic resistance)of the glass surface near the cahode surface(air side)increases,and litde change is found in that of the side(tin permeability surface).%在玻璃退火温度范围内,对钠钙硅酸盐平板玻璃施加高压电场.研究了高压电场下处理温度、时间、电场强度及泄露电流对玻璃化学稳定性的影响.利用化学滴定法测试了玻璃表面析碱量,研究了玻璃的耐水性.利用恒温恒湿箱进行了加速风化实验,采用XJZ-6型金相显微镜观察玻璃样品风化后的形貌.实验表明,泄露电流强度不大于150 μA/cm~2,高压电场提高正极附近玻璃表面(空气面)的化学稳定性,同时负极附近玻璃表面(渗锡面)的化学稳定性变化不大.

  20. Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation.

    Science.gov (United States)

    Fu, Qiang; Rahaman, Mohamed N; Fu, Hailuo; Liu, Xin

    2010-10-01

    Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3. PMID:20544804

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

    Science.gov (United States)

    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.

  2. Experimental study on preparation of sodium silicate by purification of gangue and alkali melting activation%煤矸石除杂及碱融活化制取硅酸钠的实验研究

    Institute of Scientific and Technical Information of China (English)

    孔德顺; 吴红

    2013-01-01

    研究利用煤矸石中的硅元素制取硅酸钠,先将煤矸石粉在750℃下煅烧2h,除去有机质并破坏了煤矸石中的高岭石等矿物的晶型结构,再将煅烧过的煤矸石粉在95℃、液固比(mL/g)为8:1、质量分数为40%的硫酸中酸浸5h,煤矸石煅烧粉中的铁和铝等金属杂质离子的总去除率为86.93%;还研究了碱融活化条件对硅元素溶出率的影响,获得了适宜的碱融活化条件:m(酸浸粉):m(碳酸钠)=1:1.5、碱融温度为800 ℃、碱融时间为2h.在此条件下,硅元素溶出率大于75%,最终获得了硅酸钠溶液.%In order to utilize silicon in the coal gangue to prepare sodium silicate,the gangue powder was calcined at 750 ℃for 2 h firstly,then the organic matters were removed and the crystal structures of the minerals,such as kaolin in the gangue were destroyed.The calcined gangue powder was leached in sulfuric acid with mass fraction of 40% and liquid to solid ratio of 8:l at 95 ℃ for 5 h.The total removal ratio of impurity metal ions,such as iron and aluminum was 86.93%;the influences of the alkali melting activation conditions on the dissolution ratios of silicon element were investigated,then the suitable activation conditions were obtained:the mass ratio of acid leaching powder to sodium carbonate was 1:1.5,the alkali melting temperature was 800 ℃,and the alkali melting time was 2 h.Under these conditions silicon element dissolution ratio was more than 75% and the sodium silicate solution was obtained finally.

  3. Better Alternative to "Astronomical Silicate": Laboratory-Based Optical Functions of Chondritic/Solar Abundance Glass With Application to HD161796

    CERN Document Server

    Speck, A K; Hofmeister, A M

    2015-01-01

    "Astronomical" or "circumstellar" silicate optical functions (real and imaginary indices of refraction n and k have been previously derived from compositionally and structurally disparate samples; past values were compiled from different sources in the literature, and are essentially kluges of observational, laboratory, and extrapolated or interpolated values. These synthetic optical functions were created because astronomers lack the quantitative data on amorphous silicates at all wavelengths needed for radiative transfer modeling. This paper provides optical functions that (1) are created with a consistent methodology, (2) use the same sample across all wavelengths, and (3) minimize interpolation and extrapolation wherever possible. We present electronic data tables of optical functions derived from mid-ultraviolet to far-infrared laboratory transmission spectra for two materials: iron-free glass with chondritic/solar atmospheric abundances, and metallic iron. We compare these optical functions to other pop...

  4. Structure of glasses containing transition-metal ions. Progress report, January 1, 1982-October 31, 1982

    International Nuclear Information System (INIS)

    Investigations of host glasses include the completion of an interpretation of the Raman spectra of soda-gallia-silica glasses and some new work on zinc-containing glasses. The question of the structural environment of transition metal ions in silicate glasses and whether these ions should be regarded as occupying sites (a crystal-like model) or whether they form complexes (a solution-like model) continues to occupy our attention. A study of cobalt in alkali silicate glasses was completed and work is underway on chromium in borate glasses. The investigation of diffusion processes and the hydration of glass surfaces by sputter-induced-photon spectrometry (SIPS) was completed and the final portions are reported

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

    International Nuclear Information System (INIS)

    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 1 h. 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. - Highlights: • The addition of zinc to glasses decreased Tg and promoted crystallisation. • Zinc enhanced the sintering ability and increased mechanical strength by 36%. • The apatite formation ability decreased with increasing Zn contents. • Zinc stimulated mesenchymal stem cell proliferation in a dose dependent manner

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

    Energy Technology Data Exchange (ETDEWEB)

    Kapoor, Saurabh [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Goel, Ashutosh [Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8065 (United States); Correia, Ana Filipa [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Pascual, Maria J. [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, 28049 Madrid (Spain); Lee, Hye-Young; Kim, Hae-Won [Institute of Tissue Regeneration Engineering (ITREN) & College of Dentistry, Dankook University, Cheonan 330714 (Korea, Republic of); Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Centre for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Ferreira, José M.F., E-mail: jmf@ua.pt [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

    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 P{sub 2}O{sub 5}–38.49 SiO{sub 2}–0.59 CaF{sub 2} (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 1 h. 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. - Highlights: • The addition of zinc to glasses decreased T{sub g} and promoted crystallisation. • Zinc enhanced the sintering ability and increased mechanical strength by 36%. • The apatite formation ability decreased with increasing Zn contents. • Zinc stimulated mesenchymal stem cell proliferation in a dose dependent manner.

  7. Mechanical and microstructural properties of alkali-activated fly ash geopolymers.

    Science.gov (United States)

    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.

  8. Mechanical and microstructural properties of alkali-activated fly ash geopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Komljenovic, M., E-mail: miroslav.komljenovic@imsi.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bascarevic, Z., E-mail: zvezdana@cms.bg.ac.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bradic, V., E-mail: violeta.bradic@cms.bg.ac.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia)

    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){sub 2}, NaOH, NaOH + Na{sub 2}CO{sub 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 {mu}m), 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{sub 2}/Na{sub 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. Effect of Er{sub 2}O{sub 3} dopant on electrical and optical properties of potassium sodium niobate silicate glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yongsiri, Ploypailin [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sirisoonthorn, Somnuk [National Metal and Materials Technology Center, Pathumthani 12120 (Thailand); Pengpat, Kamonpan, E-mail: kamonpan.p@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-09-15

    Highlights: • The KNN–SiO{sub 2} doped Er{sub 2}O{sub 3} glass-ceramics was prepared by incorporation method. • High dielectric constant (458.41 at 100 kHz) and low loss (0.0005) could be obtained. • TEM and SEM confirmed the existence of KNN crystals embedded in glass matrix. • The Er{sub 2}O{sub 3} dopant causes insignificant effect on modifying E{sub g} value. - Abstract: In this study, transparent glass-ceramics from potassium sodium niobate (KNN)-silicate glass system doped with erbium oxide (Er{sub 2}O{sub 3}) were successfully prepared by incorporation method. KNN was added in glass batches as heterogeneous nucleating agent. The KNN powder was mixed with SiO{sub 2} and Er{sub 2}O{sub 3} dopant with KNN and Er{sub 2}O{sub 3} content varied between 70–80 and 0.5–1.0 mol%, respectively. Each batch was subsequently melted at 1300 °C for 15 min in a platinum crucible using an electric furnace. The quenched glasses were then subjected to heat treatment at various temperatures for 4 h. XRD results showed that the prepared glass ceramics contained crystals of KNN solid solution. In contrary, dielectric constant (ϵ{sub r}) and dielectric loss (tan δ) were found to increase with increasing heat treatment temperature. Additionally, optical properties such as absorbance and energy band gap have been investigated.

  10. Mixed alkali effect in borate glasses - electron paramagnetic resonance and optical absorption studies in Cu sup 2 sup + doped xNa sub 2 O- (30 - x)K sub 2 O- 70B sub 2 O sub 3 glasses

    CERN Document Server

    Chakradhar, R P S; Rao, J L; Ramakrishna, J

    2003-01-01

    The mixed alkali borate glasses xNa sub 2 O-(30 - x)K sub 2 O-70B sub 2 O sub 3 (5 sup sup 2 B sub 2 sub g) and a weak band on the higher energy side at 22 115 cm sup - sup 1 corresponding to the transition ( sup 2 B sub 1 sub g -> sup 2 E sub g). With x > 5, the higher energy band disappears and the lower energy band shifts slightly to the lower energy side. By correlating the EPR and optical absorption data, the molecular orbital coefficients alpha sup 2 and beta sub 1 sup 2 are evaluated for the different glasses investigated. The values indicate that the in-plane sigma bonding is moderately covalent while the in-plane pi bonding is significantly ionic in nature; these exhibit a minimum with x = 15, showing the MAE. The theoretical values of optical basicity of the glasses have also been evaluated. From optical absorption edges, the optical bandgap energies have been calculated and are found to lie in the range 3.00-3.40 eV. The physical properties of the glasses studied have also been evaluated with respe...

  11. The influence of different parameters on the hydration process of binders based on alkali activated slag

    Directory of Open Access Journals (Sweden)

    DARKO KRIZAN

    2005-02-01

    Full Text Available The influence of certain types of activators (water glass Na2O·nSiO2 and sodium-metasilicate Na2SiO3·5H2O on the hydration process of alkali activated slag was investigated in this study. The influence of activator concentration, specific surface area of the slag and the modulus n of the water glass (mass ratio between SiO2 and Na2O on the kinetics of the hydration process i.e., the change of compressive strength were also investigated. Poorly crystallized low base calcium silicate hydrate C–S–H (I is the main hydration product of alkali activated slag regardless of the activator used. This is the reason for the rapid increase in the strength of alkali activated slag and also of the very high strength values. The strength growth rate and strength values were significantly higher when sodium–metasilicate was used as the activator than when water glass was used. The specific surface area of the slag and the activator concentration are parameters which have a closely connected influence on strength and their action is cumulative. The modulus n of water glass does not have an explicit influence on the strength of alkali activated slag.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  14. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Farah, Khaled, E-mail: kafarah@gmail.com [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); ISTLS, University of Sousse (Tunisia); Hosni, Faouzi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Academie Militaire de Fondouk Jedid, 8012 Nabeul (Tunisia); Mejri, Arbi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Boizot, Bruno [Laboratoire des Solides Irradiés, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Hamzaoui, Ahmed Hichem [Centre National de Recherche en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Ben Ouada, Hafedh [Laboratoire des Interfaces et Matériaux Avancés, Faculté des Sciences, University of Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia)

    2014-03-15

    Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO{sub 3} and NaNO{sub 3} with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy.

  15. Enamel and Dentin Surface Finishing Influence on the Roughness and Microshear Bond Strength of a Lithium Silicate Glass-Ceramic for Laminate Veneers

    Science.gov (United States)

    Gonzaga, Carla Castiglia; Bravo, Ruth Peggy; Pavelski, Thiago Vinícius; Garcia, Paula Pontes; Correr, Gisele Maria; Leonardi, Denise Piotto; da Cunha, Leonardo Fernandes; Furuse, Adilson Yoshio

    2015-01-01

    Objectives. This study evaluated the influence of cavity surface finishing with diamond burs of different grit mounted on high-speed turbine and ultrasound on the roughness and microshear bond strength (MBS) of a lithium silicate glass-ceramic to enamel and dentin. Methods. Enamel and dentin specimens were divided into seven groups, according to the type of surface finishing: 1200-grit sandpaper (control), two different brands of medium-grit and fine-grit diamond burs in a high-speed turbine; medium-grit and fine-grit CVD (chemical vapor deposition) tips in an ultrasonic device. Roughness parameters (n = 5) and MSBS to a glass-ceramic (n = 10) were determined. Data were analyzed using ANOVA and Tukey's test (α = 5%). Results. Control group showed lower mean roughness readings and groups that used medium-grit diamond burs showed the highest mean roughness values. Regarding MSBS, there was no statistical difference when comparing the groups gritted with the same brand of medium- and fine-grit burs and tips. Conclusions. Cavity surface finishing influenced the roughness parameters and MSBS of a glass-ceramic to enamel and dentin. Medium-grit diamond burs in high-speed turbine showed the highest mean roughness values. Fine-grit CVD tips in ultrasound presented the highest MSBS values for both enamel and dentin. PMID:27347507

  16. High content silicate porous glasses used for radioactive wastes storage: preparation and characterization of the spinodal decomposition

    International Nuclear Information System (INIS)

    The phase separation behavior via spinodal decomposition of two sodium borosilicate glasses has been studied having the following compositions in weight %: Glass A: 8% Na2 O - 32% B2O3 - 60% Si O2 Glass 8% B: Na2 O -27% B2 O3 - 65% Si O2. The growth of the mean size r of the minor phase microstructure has been determined as a function of both the time length (0-100 hours) and the heat treatment by analyzing temperature 580, 6000 C of the glass sample images obtained with a Scanning Electron Microscope. The results are in good agreement with the theory of Lifshitz-Slyozov which predict a growth of the minor phase microstructure via a diffusion controlled process through the insoluble phase such that r-bar = Ao t e - ΔE/R T. The activation energy ΔE and the pre-exponential factor Ao of the diffusion process were found ΔE = 58,8 kCal/mol; Ao = 8,42 x 1021 Angstrom3/h for the glass A and ΔE = 92,6 kCal/mol; Ao = 4,84 x 1029 Angstrom3/h for the glass B. The distribution curves of the microstructure size allowed to suggest for the glasses under study the most adequate heat treatments to absorbs after the leaching of the soluble phase. (author)

  17. Sol-gel synthesis and in vitro bioactivity of copper and zinc-doped silicate bioactive glasses and glass-ceramics.

    Science.gov (United States)

    Bejarano, Julian; Caviedes, Pablo; Palza, Humberto

    2015-04-01

    Metal doping of bioactive glasses based on ternary 60SiO2-36CaO-4P2O5 (58S) and quaternary 60SiO2-25CaO-11Na2O-4P2O5 (NaBG) mol% compositions synthesized using a sol-gel process was analyzed. In particular, the effect of incorporating 1, 5 and 10 mol% of CuO and ZnO (replacing equivalent quantities of CaO) on the texture, in vitro bioactivity, and cytocompatibility of these materials was evaluated. Our results showed that the addition of metal ions can modulate the textural property of the matrix and its crystal structure. Regarding the bioactivity, after soaking in simulated body fluid (SBF) undoped 58S and NaBG glasses developed an apatite surface layer that was reduced in the doped glasses depending on the type of metal and its concentration with Zn displaying the largest inhibitions. Both the ion release from samples and the ion adsorption from the medium depended on the type of matrix with 58S glasses showing the highest values. Pure NaBG glass was more cytocompatible to osteoblast-like cells (SaOS-2) than pure 58S glass as tested by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The incorporation of metal ions decreased the cytocompatibility of the glasses depending on their concentration and on the glass matrix doped. Our results show that by changing the glass composition and by adding Cu or Zn, bioactive materials with different textures, bioactivity and cytocompatibility can be synthesized.

  18. Silicates materials of high vacuum technology

    CERN Document Server

    Espe, Werner

    2013-01-01

    Materials of High Vacuum Technology, Volume 2: Silicates covers silicate insulators of special importance to vacuum technology. The book discusses the manufacture, composition, and physical and chemical properties of technical glasses, quartz glass, quartzware, vycor glass, ceramic materials, mica, and asbestos.

  19. A structural investigation of the alkali metal site distribution within bioactive glass using neutron diffraction and multinuclear solid state NMR.

    Science.gov (United States)

    Martin, Richard A; Twyman, Helen L; Rees, Gregory J; Smith, Jodie M; Barney, Emma R; Smith, Mark E; Hanna, John V; Newport, Robert J

    2012-09-21

    The atomic-scale structure of Bioglass and the effect of substituting lithium for sodium within these glasses have been investigated using neutron diffraction and solid state magic angle spinning (MAS) NMR. Applying an effective isomorphic substitution difference function to the neutron diffraction data has enabled the Na-O and Li-O nearest-neighbour correlations to be isolated from the overlapping Ca-O, O-(P)-O and O-(Si)-O correlations. These results reveal that Na and Li behave in a similar manner within the glassy matrix and do not disrupt the short range order of the network former. Residual differences are attributed solely to the variation in ionic radius between the two species. Successful simplification of the 2 bioactive glasses, and an analogous splitting of the Li-O correlations. The observed correlations are attributed to the metal ions bonded either to bridging or to non-bridging oxygen atoms. (23)Na triple quantum MAS (3QMAS) NMR data corroborates the split Na-O correlations. The structural sites present will be intimately related to the release properties of the glass system in physiological fluids such as plasma and saliva, and hence to the bioactivity of the material. Detailed structural knowledge is therefore a prerequisite for optimizing material design. PMID:22868255

  20. Formation and bleaching of induced colour centres in gamma-irradiated vanadium-containing alkali-borate glasses

    International Nuclear Information System (INIS)

    The nature of radiation-induced defects and defect generation process in glasses of the base composition B2O3 and R2O + 0.5 g V2O5, where R is Li2O, Na2O or K2O were studied. The glasses were exposed to successive irradiation doses up to 17 kGy and their optical absorption spectra were measured in the range 200-1100 nm. Three factors were investigated: the role of V2O5, the effect of chemical composition, irradiation doses and the decay of colour centres by heat treatment at 200oC. The optical spectra have been shown to reveal the presence of V3+, V4+ and V5+ ions altogether in varying proportions. The response of the glass to irradiation is related to the competition between formation and annihilation of induced defects and hence the observed characteristic colour centres. The rate of thermal bleaching at interval times was discussed. (author)

  1. Glass substrates crosslinked with tetracycline-imprinted polymeric silicate and CdTe quantum dots as fluorescent sensors.

    Science.gov (United States)

    Chao, Mu-Rong; Hu, Chiung-Wen; Chen, Jian-Lian

    2016-06-21

    A fluorescence-based sensor that combines the merits of quantum dots (QDs) and molecularly imprinted polymers (MIPs) was first fabricated on a glass substrate via a sol-gel route. Some of the key performance factors, including silane selection, substrate etching, the reaction times of glass silanization and sol-gel polymerization, and the times and methods used for template stripping and loading, were discussed and determined. After fabricating the sensor on either a 3-aminopropyltriethoxysilane (APS) or a 3-mercaptopropyltriethoxysilane (MPS) modified glass substrate, APS showed a much better performance than MPS as both the capping reagent of QDs and the functional monomer of tetracycline-templated MIPs. The APS-QDs on APS-modified glass had a higher imprinted factor (IF = 5.6), a lower LOD (2.1 μM, 3σ), and a more stable signal (2.8%, n = 10 at 70 μM) than those on the MPS-modified glass (IF = 5.2, LOD = 6.5 μM, stability = 6.2%). Furthermore, the recoveries of tetracycline (70 μM) from BSA (133 μg/mL) and FBS (0.66 ppt) by the APS-modified glass were 98% (RSD = 3.5%, n = 5) and 97% (RSD = 5.7%), respectively. For the MPS-modified glass, recoveries of 95% (RSD = 7.2%) and 89% (RSD = 8.7%) were observed at 67 μg/mL of BSA and 0.33 ppt of FBS, respectively. PMID:27188318

  2. Extraction of Soluble Sodium Silicate using Corn Cob Ash as a Silica Source

    Directory of Open Access Journals (Sweden)

    B.A. Ajayi

    2015-09-01

    Full Text Available Extraction of soluble sodium silicate was carried out in this study using corn cob ash as silica source and alkali as soda source. Initially, received corn cob was burnt in open air to obtain the corn cob ash. The obtained corn cob ash was then placed inside refractory crucible and further heating was carried out inside muffle furnace at the temperature of 6000C for 5hrs. The thermally treated corn cob ash was mixed with 3M conc. NAOH and boiled with a constant stirring in a heating glass vessel placed inside a thermostatic water bath at 800C for 4hrs and 900C for 3hrs respectively. Various analyses such as PH value, specific gravity, electrical conductivity, viscosity were conducted on the produced sodium silicate and the results were compared with the reference sodium silicate sample.

  3. A structural investigation of the alkali metal site distribution within bioactive glass using neutron diffraction and multinuclear solid state NMR

    OpenAIRE

    Martin, R A; Twyman, H.L.; Rees, G.J.; Smith, J M; Barney, E. R.; Smith, M E; Hanna, J. V.; Newport, Robert J.

    2012-01-01

    The atomic-scale structure of Bioglass and the effect of substituting lithium for sodium within these glasses have been investigated using neutron diffraction and solid state magic angle spinning (MAS) NMR. Applying an effective isomorphic substitution difference function to the neutron diffraction data has enabled the Na-O and Li-O nearest-neighbour correlations to be isolated from the overlapping Ca-O, O-(P)-O and O-(Si)-O correlations. These results reveal that Na and Li behave in a simila...

  4. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    also increases such properties. Yet, these rules are not strictly followed even for the simplest binary oxide glasses, such as alkali silicates, borates and phosphates. In this thesis it is argued that the missing link between composition and properties is the glass structure. Structural models are......The composition of glass can be varied continuously within their glass-forming regions. This compositional flexibility makes it possible to tailor the properties of a glass for a variety of specific uses. In the industry such tailoring is done on a trial-and-error basis with only the intuition of a...... proposed based on topological selection rules and experimentally verified. The relation between structure and properties is evaluated using topological constraint theory, which in its essence is a theory that quantifies the two intuitions of the glass scientist. The end result is a quantitative model...

  5. Intrinsic single- and multiple-pulse laser-induced damage in silicate glasses in the femtosecond-to-nanosecond region

    International Nuclear Information System (INIS)

    We show that the threshold power density of the intrinsic laser-induced damage in borosilicate glass at ∼1 μm wavelength does not depend on pulse duration from 2x10-13 to 3x10-8 s and has the same value for both single- and multiple-pulse exposure of the sample. This indicates that the mechanism of the intrinsic damage in glasses involves a collective response of a certain volume in the dielectric as a whole, such as 'dielectric-metal' phase transition, rather than a process of individual generation and accumulation of electrons, such as multiphoton, tunneling, or avalanche. Also, we demonstrate that under femtosecond exposure the threshold of the plasma formation in transparent glasses is considerably higher than the threshold of the residual change of medium parameters

  6. Electrical Relaxation in Mixed Alkali Bi2O3-K2O-Li2O-Fe2O3 Glasses

    Institute of Scientific and Technical Information of China (English)

    E.E.Shaisha; Sh.F.El-Desouki; I.Shaltout; A.A.Bahgat

    2006-01-01

    A new glass system(Bi2O3)50(Fe2O3)10(Li2O)x(K2O)40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect(MAE)phenomena.Measurements of ac conductivity σac, dielectric permittivity ε' and loss factor tanδ in the frequency range of 0.12~102 kHz and in the temperature range of 300~650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ωs, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling(OLPT)model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε' and real dielectric modulus M'show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M" are insignificantly dependent on composition even at the same transition temperature Tg.

  7. Determination of lead, uranium, thorium, and thallium in silicate glass standard materials by isotope dilution mass spectrometry

    Science.gov (United States)

    Barnes, I.L.; Garner, E.L.; Gramlich, J.W.; Moore, L.J.; Murphy, T.J.; Machlan, L.A.; Shields, W.R.; Tatsumoto, M.; Knight, R.J.

    1973-01-01

    A set of four standard glasses has been prepared which have been doped with 61 different elements at the 500-, 50-, 1-, and 0.02-ppm level. The concentrations of lead, uranium, thorium, and thallium have been determined by isotope dilution mass spectrometry at a number of points in each of the glasses. The results obtained from independent determinations in two laboratories demonstrate the homogeneity of the samples and that precision of the order of 0.5% (95% L.E.) may be obtained by the method even at the 20-ppb level for these elements. The chemical and mass spectrometric procedures necessary are presented.

  8. Nickel-assisted growth and selective doping of spinel-like gallium oxide nanocrystals in germano-silicate glasses for infrared broadband light emission

    International Nuclear Information System (INIS)

    The target of taking advantage of the near-infrared light-emission properties of nickel ions in crystals for the design of novel broadband optical amplifiers requires the identification of suitable nanostructured glasses able to embed Ni-doped nanocrystals and to preserve the workability of a glass. Here we show that Ni doping of Li2O–Na2O–Ga2O3–GeO2–SiO2 glass (with composition 7.5:2.5:20:35:35 and melting temperature 1480 °C, sensibly lower than in Ge-free silicates) enables the selective embedding of nickel ions in thermally grown nanocrystals of spinel-like gallium oxide. The analysis of transmission electron microscopy and x-ray diffraction data as a function of Ni-content (from 0.01 to 1 mol%) indicates that Ni ions promote the nanophase crystallization without affecting nanoparticle size (∼6 nm) and concentration (∼4 × 1018 cm−3). Importantly, as shown by optical absorption spectra, all nickel ions enter into the nanophase, with a number of ions per nanocrystal that depends on the nanocrystal concentration and ranges from 1 to 102. Photoluminescence data indicate that fast non-radiative decay processes become relevant only at mean ion–ion distances shorter than 1.4 nm, which enables the incorporation of a few Ni ions per nanoparticle without too large a worsening of the light-emission efficiency. Indeed, at 0.1 mol% nickel, the room temperature quantum yield is 9%, with an effective bandwidth of 320 nm.

  9. Visible and near infrared up-conversion luminescence in Yb{sup 3+}/Tm{sup 3+} co-doped yttria-alumino-silicate glass based optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Arindam [Fiber Optics and Photonics Division, Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), Jadavpur, Kolkata-700032 (India); Chandra Paul, Mukul, E-mail: mcpal1266@gmail.com [Fiber Optics and Photonics Division, Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), Jadavpur, Kolkata-700032 (India); Wadi Harun, Sulaiman [Depertment of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kumar Bhadra, Shyamal, E-mail: skbhadra@cgcri.res.in [Fiber Optics and Photonics Division, Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), Jadavpur, Kolkata-700032 (India); Bysakh, Sandip [Electron Microscopy Section, Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), Jadavpur, Kolkata-700032 (India); Das, Shyamal; Pal, Mrinmay [Fiber Optics and Photonics Division, Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), Jadavpur, Kolkata-700032 (India)

    2013-11-15

    We report blue light up-conversion (UC) emission in Yb–Tm co-doped nano-phase separated yttria-alumino-silicate (YAS) glass based D-shaped with low-index cladding optical fibers. Y{sub 2}O{sub 3} creates an environment of nano structured YAS glass phases with Yb and Tm rich zone into the core glass which confirmed from TEM analyses. This kind of glass host assists in distributing of Yb and Tm rich zone uniformly throughout the core region. Yb and Tm doped regions exist mainly into nano YAS phases, defined as RE rich nano YAS-RE phases. All samples exhibit UC luminescence peaks at 483 nm, 650 nm and 817 nm for Tm{sup 3+} and 1044 nm for Yb{sup 3+} under excitation by 975 nm laser light. In such type of nano-engineered glass–ceramic based host, almost all the Yb ions transferred its energy to the nearer Tm ions. In particular 483 nm emission is attributed to {sup 1}G{sub 4}→{sup 3}H{sub 6} transition through a three step resonance energy transfer (ET) from excited Yb{sup 3+}. The highest emission intensity is obtained with a concentration of 0.5 wt% Tm{sup 3+} and 2.0 wt% Yb{sup 3+}. The ET between Yb{sup 3+} and Tm{sup 3+} is increased with increase of Yb{sup 3+} concentration with respect to Tm{sup 3+}. The experimental fluorescence life-times of Tm{sup 3+} upconversion emission at visible wavelengths into such kind of fiber is reported under 975 nm pump excitation. The present study is important for development of an efficient tunable 483 nm fluorescence light source. -- Highlights: • We report nano-phase separated YAS glass host based Yb–Tm co-doped optical fibers. • Almost all the Yb transferred its energy to the neighboring Tm ions. • We report strong UC luminescence peaks at 483 nm and 817 nm wavelengths. • We report third ET coefficient as 1.6723 Hz for such kind of Yb–Tm codoped fiber. • We report suitable fiber as an efficient tunable 483 nm fluorescence light source.

  10. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    OpenAIRE

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Robert J. Flatt; D'Espinose De Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measuremen...

  11. Comparative investigation on the effect of alkaline earth oxides on the intensity of absorption bands due to Cu2+, Mn3+ and Cr3+ ions in ternary silicate glasses

    Indian Academy of Sciences (India)

    S P Singh; Aman; Anal Tarafder

    2004-06-01

    Absorption characteristics of Cu2+, Mn3+ and Cr3+ ions in ternary silicate (20Na2O.10RO.70SiO2, where R=Ca, Sr, Ba) glasses were investigated. The intensities of absorption bands due to Cu2+ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case of Mn3+ and Cr3+ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu2+, Mn3+ and Cr3+ ion is attributed due to change in silicate glass compositions.

  12. Influence of alkali mixed effect on the mixing enthalpy in 0.7582O3-0.25[xNa2O-(1-x)K2O]glass system

    Institute of Scientific and Technical Information of China (English)

    A.Kouyate; A.E Ahoussou; A.Yapi; D.Diabate; J.Rogez; A.Trokourey

    2008-01-01

    The mixed alkali effect was investigated in the glass system 0.7582O3-0.25[xNa2O-(1-x)K2O]through thermodynamic properties.The calorimetric measurements were performed in HF solution calorimetry at 298 K,The mixing enthalpy values show non-linear behaviour upon substitution of one alkali ion by another.This thermodynamic non-idealiIy is caused by the slight variations of distance between metallic cations,the macromolecular structure being unchanged.It can be explained,at least qualitatively,using electrolyte theory based on the Coulombic interactions of charged species originally developed by Debye and Hiickel.

  13. Extraction of Soluble Sodium Silicate using Corn Cob Ash as a Silica Source

    OpenAIRE

    Ajayi, B.A.; S.S. Owoeye

    2015-01-01

    Extraction of soluble sodium silicate was carried out in this study using corn cob ash as silica source and alkali as soda source. Initially, received corn cob was burnt in open air to obtain the corn cob ash. The obtained corn cob ash was then placed inside refractory crucible and further heating was carried out inside muffle furnace at the temperature of 6000C for 5hrs. The thermally treated corn cob ash was mixed with 3M conc. NAOH and boiled with a constant stirring in a heating glass ves...

  14. Chemistry of glass corrosion in high saline brines

    International Nuclear Information System (INIS)

    Corrosion data obtained in laboratory tests can be used for the performance assessment of nuclear waste glasses in a repository if the data are quantitatively described in the frame of a geochemical model. Experimental data were obtained for conventional pH values corrected for liquid junction, amorphous silica solubility and glass corrosion in concentrated salt brines. The data were interpreted with a geochemical model. The brine chemistry was described with the Pitzer formalism using a data base which allows calculation of brine compositions in equilibrium with salt minerals at temperatures up to 200C. In MgCl2 dominated brines Mg silicates form and due to the consumption of Mg the pH decreases with proceeding reaction. A constant pH (about 4) and composition of alteration products is achieved, when the alkali release from the glass balances the Mg consumption. The low pH results in high release of rare earth elements REE (rare earth elements) and U from the glass. In the NaCl dominated brine MgCl2 becomes exhausted by Mg silicate formation. As long as there is still Mg left in solution the pH decreases. After exhaustion of Mg the pH rises with the alkali release from the glass and analcime is formed

  15. Carbonation of metal silicates for long-term CO2 sequestration

    Science.gov (United States)

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

    2014-03-18

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

  16. Structure and rheological properties in alkali aluminosilicate melts

    Science.gov (United States)

    Le Losq, Charles; Neuville, Daniel

    2010-05-01

    Rheological properties of silicate melts govern both magma ascension from the mantle to the surface of the earth and volcanological eruptions styles and behaviors. In this mind, it is very important to understand which parameters influence these properties. Up to now, we know for example that viscosity of silicate melts is dependent of temperature, pressure and chemical composition. 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 haplogranitic rhyolitic alkali magmas. We will first present our viscosity measurements and some modelisation concepts based on the Adam and Gibbs theory. From configurational entropy theory we obtain some macroscopic information's that we can link to the structure of glasses and melts. In this mind, we have investigated them with Raman and NMR spectroscopies. These spectroscopies provide information on speciation and polymerization of glasses and melts. We will present and discuss structural and rheological variations as a function of temperature and chemical change.

  17. Glasses

    DEFF Research Database (Denmark)

    Dyre, Jeppe

    2004-01-01

    The temperature dependence of the viscosity of most glassforming liquids is known to depart significantly from the classical Arrhenius behaviour of simple fluids. The discovery of an unexpected correlation between the extent of this departure and the Poisson ratio of the resulting glass could lead...... to new understanding of glass ageing and viscous liquid dynamics....

  18. Annual progress report to Battelle Pacific Northwest National Laboratories on prediction of phase separation of simulated nuclear waste glasses

    International Nuclear Information System (INIS)

    The objective of this research is to predict the immiscibility boundaries of multi-component borosilicate glasses, on which many nuclear waste glass compositions are based. The method used is similar to the prediction method of immiscibility boundaries of multi-component silicate glass systems successfully made earlier and is based upon the superposition of immiscibility boundaries of simple systems using an appropriate parameter. This method is possible because many immiscibility boundaries have similar shapes and can be scaled by a parameter. In the alkali and alkaline earth binary silicate systems, for example, the critical temperature and compositions were scaled using the Debye-Hueckel theory. In the present study on borosilicate systems, first, immiscibility boundaries of various binary alkali and alkaline borate glass systems (e.g. BaO-B2O3) were examined and their critical temperatures were evaluated in terms of Debye-Hueckel theory. The mixing effects of two alkali and alkaline-earth borate systems on the critical temperature were also explored. Next immiscibility boundaries of ternary borosilicate glasses (e.g. Na2O-SiO2-B2O3, K2O-SiO2-B2O3, Rb2O-SiO2-B2O3, and Cs2O-SiO2-B2O3) were examined. Their mixing effects are currently under investigation

  19. A study of redox kinetic in silicate melt

    International Nuclear Information System (INIS)

    The aim of this thesis is to understand better iron redox reactions and mechanisms in silicate glasses and melts. Particular interest has been paid to the influence of temperature and chemical composition. For this purpose, the influence of alkali element content, iron content and network formers on the kinetics of redox reactions has been determined through XANES and Raman spectroscopy experiments performed either near the glass transition or above the liquidus temperature. As a complement, electrical conductivity and RBS spectroscopy experiments have been made to characterize the diffusivity of the species that transport electrical charges and the reaction morphology, respectively. Temperature and composition variations can induce changes in the dominating redox mechanism. At a given temperature, the parameters that exert the strongest influence on redox mechanisms are the presence or lack of divalent cations and the existing decoupling between the mobility of network former and modifier elements. Near Tg, the diffusion of divalent cations, when present in the melt, controls the kinetics of iron redox reactions along with a flux of electron holes. Composition, through the degree of polymerization and the silicate network structure, influences the kinetics and the nature of the involved cations, but not the mechanisms of the reaction. Without alkaline earth elements, the kinetics of redox reactions are controlled by the diffusion of oxygen species. With increasing temperatures, the diffusivities of all ionic species tend to become similar. The decoupling between ionic fluxes then is reduced so that several mechanisms become kinetically equivalent and can thus coexist. (author)

  20. A study of redox kinetic in silicate melt; Etude cinetique des reactions d'oxydoreduction dans les silicates

    Energy Technology Data Exchange (ETDEWEB)

    Magnien, V

    2005-12-15

    The aim of this thesis is to understand better iron redox reactions and mechanisms in silicate glasses and melts. Particular interest has been paid to the influence of temperature and chemical composition. For this purpose, the influence of alkali element content, iron content and network formers on the kinetics of redox reactions has been determined through XANES and Raman spectroscopy experiments performed either near the glass transition or above the liquidus temperature. As a complement, electrical conductivity and RBS spectroscopy experiments have been made to characterize the diffusivity of the species that transport electrical charges and the reaction morphology, respectively. Temperature and composition variations can induce changes in the dominating redox mechanism. At a given temperature, the parameters that exert the strongest influence on redox mechanisms are the presence or lack of divalent cations and the existing decoupling between the mobility of network former and modifier elements. Near Tg, the diffusion of divalent cations, when present in the melt, controls the kinetics of iron redox reactions along with a flux of electron holes. Composition, through the degree of polymerization and the silicate network structure, influences the kinetics and the nature of the involved cations, but not the mechanisms of the reaction. Without alkaline earth elements, the kinetics of redox reactions are controlled by the diffusion of oxygen species. With increasing temperatures, the diffusivities of all ionic species tend to become similar. The decoupling between ionic fluxes then is reduced so that several mechanisms become kinetically equivalent and can thus coexist. (author)

  1. Ion-Exchange Processes and Mechanisms in Glasses

    International Nuclear Information System (INIS)

    Leaching of alkalis from glass is widely recognized as an important mechanism in the initial stages of glass-water interactions. Pioneering experimental studies [1-3] nearly thirty-five years ago established that alkali (designated as M+) are lost to solution more rapidly than network-forming cations. The overall chemical reaction describing the process can be written as: (triplebond)Si-O-M + H+ → (triplebond)Si-OH + M+ (1) or (triplebond)Si-O-M + H3O+ → (triplebond)Si-OH + M+ + H2O. (2) Doremus and coworkers [4-7] fashioned a quantitative model where M+ ions in the glass are exchanged for counter-diffusing H3O+ or H+. Subsequent investigations [8], which have relied heavily on reaction layer analysis, recognized the role of H2O molecules in the alkali-exchange process, without minimizing the importance of charged hydrogen species. Beginning in the 1980s, however, interest in M+-H+ exchange reactions in silicate glasses diminished considerably because important experimental observations showed that network hydrolysis and dissolution rates were principally controlled by the chemical potential difference between the glass and solution (chemical affinity) [9]. For nuclear waste glasses, formation of alteration products or secondary phases that remove important elements from solution, particularly Si, was found to have very large impacts on glass dissolution rates [10,11]. Consequently, recent work on glass/water interactions has focused on understanding this process and incorporating it into models [12]. The ion-exchange process has been largely ignored because it has been thought to be a short duration, secondary or tertiary process that had little or no bearing on long-term corrosion or radionuclide release rates from glasses [13]. The only significant effect identified in the literature that is attributed to alkali ion exchange is an increase in solution pH in static laboratory tests conducted at high surface area-to-volume ratios [14,15]. Renewed interest in

  2. Concrete alkali-silica reaction and nuclear radiation damage

    International Nuclear Information System (INIS)

    The deterioration of concrete by alkali-silica reaction of aggregates (ASR) and the effect of nuclear radiations on the ASR have been reviewed based on our studies on the mechanism of ASR and the effect of nuclear radiations on the resistivity of minerals to alkaline solution. It has been found that the ASR is initiated by the attack of alkaline solution in concrete to silicious aggregates to convert them into hydrated alkali silicate. The consumption of alkali hydroxide by the aggregates induces the dissolution of Ca2+ ions into the solution. The alkali silicate surrounding the aggregates then reacts with Ca2+ ions to convert to insoluble tight and rigid reaction rims. The reaction rim allows the penetration of alkaline solution but prevents the leakage of viscous alkali silicate, so that alkali silicate generated afterward is accumulated in the aggregate to give an expansive pressure enough for cracking the aggregate and the surrounding concrete. The effect of nuclear radiation on the reactivity of quartz and plagioclase, a part of major minerals composing volcanic rocks as popular aggregates, to alkaline solution has been examined for clarifying whether nuclear radiations accelerates the ASR. It has been found that the irradiation of these minerals converts them into alkali-reactive amorphous ones. The radiation dose for plagioclase is as low as 108 Gy, which suggests that the ASR of concrete surrounding nuclear reactors is possible to be accelerated by nuclear radiation. (author)

  3. Preliminary estudies on the use of sugar cane bagasse ash (SCBA) in the manufacture of alkali activated binders

    OpenAIRE

    Castaldelli, V.N.; Mitsuuchi Tashima, Mauro; Melges, J.L.; Monzó Balbuena, José Mª; AKASAKI, JORGE LUIS; Borrachero Rosado, María Victoria; Soriano Martinez, Lourdes; Paya Bernabeu, Jorge Juan

    2014-01-01

    Alkali activated binders require the addition of a mineral-rich amorphous silica and alumina. This paper proposes the use of a mineral residue from the burning of sugar cane bagasse. The alkali activated mixtures were prepared containing binary mixtures of sugar cane bagasse ash (SCBA) and other mineral admixtures: fly ash (FA) or blast furnace slag (BFS). As alkaline activators, mixtures of alkali (Na+ or K+) hydroxide and alkali (Na+ or K+) silicate were used. Alkali-activated pastes and mo...

  4. Oxygen isotope and petrological study of silicate inclusions in IIE iron meteorites and their relationship with H chondrites

    Science.gov (United States)

    McDermott, Kathryn H.; Greenwood, Richard C.; Scott, Edward R. D.; Franchi, Ian A.; Anand, Mahesh

    2016-01-01

    The origin of silicate-bearing irons, especially those in groups IAB, IIICD, and IIE, is poorly understood as silicate should have separated rapidly from molten metal. Here we report the results of high precision oxygen isotope analysis of silicate inclusions in eleven group IIE meteorites and a petrological study of silicate inclusions in ten IIE irons including those in Garhi Yasin and Tarahumara, which have not been described in detail before. Oxygen isotopes have also been analysed in 20 H chondrites to investigate their possible relationship with the IIE irons. Based on petrographic observations and mineral analysis, the silicate-bearing IIE meteorites have been divided into four types according to the nature of their silicate inclusions: (1) primitive chondritic, (2) evolved chondritic, (3) differentiated with >10 vol.% orthopyroxene, and (4) differentiated with oxygen isotope compositions, a genetic relationship between IIE irons and H chondrites is supported by our new data. However, derivation of both groups from one parent body seems unlikely. Instead, both groups probably sampled similar precursor materials and accreted at a similar nebular location. Our data suggest that the IIE meteorites formed on an internally heated H/HH chondrite-like body that experienced the initial stages of differentiation in response to radiogenic heating. However, prior to full differentiation the IIE parent body experienced a major hit-and-run style collision that resulted in silicate-metal mixing. The initial stages of this event involved a phase of rapid cooling that prevented unmixing of metal and silicates. Reassembly of the IIE parent body produced a large regolith blanket that facilitated subsequent slow cooling. The IIE parent body has probably experienced numerous subsequent less catastrophic collisions. The development of alkali glass textures in some differentiated inclusions is probably the result of one of these later events.

  5. Water Content of Lunar Alkali Fedlspar

    Science.gov (United States)

    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 water content of the magma ocean would have 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 likely very significant in the evolution of the lunar mantle. Conclusions: Lunar granites

  6. High effective silica fume alkali activator

    Indian Academy of Sciences (India)

    Vladimír Živica

    2004-04-01

    Growing demands on the engineering properties of cement based materials and the urgency to decrease unsuitable ecologic impact of Portland cement manufacturing represent significant motivation for the development of new cement corresponding to these aspects. One category represents prospective alkali activated cements. A significant factor influencing their properties is alkali activator used. In this paper we present a new high effective alkali activator prepared from silica fume and its effectiveness. According to the results obtained this activator seems to be more effective than currently used activators like natrium hydroxide, natrium carbonate, and water glass.

  7. Surface stress relaxation of oxide glasses: The effects on mechanical strength

    Science.gov (United States)

    Lezzi, Peter Joseph

    A new glass strengthening mechanism based upon surface compressive stress formation by surface stress relaxation of glasses that were held under a tensile stress, at a temperature lower than the glass transition temperature, in low water vapor pressure, has been demonstrated. Although glass fibers are traditionally known to become mechanically weaker when heat-treated at a temperature lower than the glass transition temperature in the presence of water vapor, the strength was found to become greater than the as-received fiber strength when fibers were subjected to a sub-critical tensile stress during heat-treatment. The observed strengthening was attributed to surface compressive residual stress formation through surface stress relaxation during the sub-critical tensile stress application in the atmosphere containing water vapor. Surface stress relaxation of the same glass fibers was shown to take place under conditions identical to those experienced by the strengthened mechanical test specimens by observing permanent bending of the fiber. Furthermore, the magnitude and presence of the residual stresses formed during bending or tensile heat-treatments were confirmed by FTIR, fiber etching, and fiber slicing methods. The method can in principle be used to strengthen any oxide glass and is not subjected to the constraints of traditional strengthening methods such as a minimum thickness for tempering, or a glass containing alkali ions for ion-exchange. Thus far, the method has been successful in strengthening silica glass, E-glass, and soda-lime silicate glass by approximately 20-30%.

  8. Y2O3掺杂对硅酸盐玻璃结构及其熔体黏度的影响%Effect of Y2O3 Dopant on Structure and Viscosity of Silicate Glass and Melt

    Institute of Scientific and Technical Information of China (English)

    王觅堂; 程金树; 李梅; 何峰

    2013-01-01

    Silicate glasses and melts, soda lime silicate glass frits with various contents of Y2O3 were prepared via melting-quenching in water The effect of Y2O3 on the structure and viscosity was investigated. The samples were characterized by Raman spectrometer and viscometer, respectively. The melting temperature was obtained based on the Arrhenius equation. Some expressions for the glass structure (i.e., fraction of non-bridging oxygen, average number of non-bridging oxygen per tetrahedron, average number of oxygen pre tetrahedron and average number of bridging comers per tetrahedron) were proposed. The results show that Y2O3 doped into soda lime silicate glass can change the [SiO4] tetrahedron structural unit, and the average number of non-bridging oxygen per tetrahedron and the average number of oxygen pre tetrahedron both increase and the average number of bridging corners per tetrahedron decreases with increasing the content of Y2O3. In addition, the incorporation of Y2O3 also decreases the viscosity and melting temperature of soda lime silicate glass.%为了探索稀土氧化物Y2O3掺杂对硅酸盐玻璃结构及其高温熔体黏度的影响,用熔融-水淬法制得了掺杂不同含量Y2O3的Na2O-CaO-SiO2系玻璃料,采用激光共聚焦Raman光谱仪和高温旋转黏度计分别对玻璃料进行了Raman光谱和黏度的测试,根据Arrhenius方程推算了玻璃的熔制温度,同时给出了计算玻璃结构中每个四面体中的氧数、非桥氧数、平均桥数及非桥氧比例的公式.结果表明:Y2O3的掺杂使得Na2O-CaO-SiO2系玻璃中,具有不同非桥氧的结构单元之间发生了一定转化.随着Y2O3掺杂量的增加,玻璃中每个四面体中的氧数和非桥氧数都逐渐增大,玻璃中每个四面体中的连接数降低.此外Y2O3的掺杂降低了Na2O-CaO-SiO2系玻璃的高温黏度与熔制温度,且与玻璃结构的变化规律相一致.

  9. Why neutron guides may end up breaking down? Some results on the macroscopic behaviour of alkali-borosilicate glass support plates under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Boffy, R.; Kreuz, M. [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9 (France); Beaucour, J., E-mail: beaucour@ill.fr [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9 (France); Köster, U. [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9 (France); Bermejo, F.J. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, E-20886 Madrid (Spain)

    2015-09-01

    In this paper we report on a first part of a study on the mechanisms leading to brittle fracture in neutron guides made of glass as structural element. Such devices are widely used to deliver thermal and cold neutron beams to experimental lines in most large neutron research facilities. We present results on macroscopic properties of samples of guide glass substrates which are subjected to neutron irradiation at relatively large fluences. The results show a striking dependence of some of the macroscopic properties such as density, shape or surface curvature upon the specific chemical composition of a given glass. The relevance of the present findings for the installation of either replacement guides at the existing facilities or for the deployment of instruments for ongoing projects such as the European Spallation Source is briefly discussed.

  10. Why neutron guides may end up breaking down? Some results on the macroscopic behaviour of alkali-borosilicate glass support plates under neutron irradiation

    International Nuclear Information System (INIS)

    In this paper we report on a first part of a study on the mechanisms leading to brittle fracture in neutron guides made of glass as structural element. Such devices are widely used to deliver thermal and cold neutron beams to experimental lines in most large neutron research facilities. We present results on macroscopic properties of samples of guide glass substrates which are subjected to neutron irradiation at relatively large fluences. The results show a striking dependence of some of the macroscopic properties such as density, shape or surface curvature upon the specific chemical composition of a given glass. The relevance of the present findings for the installation of either replacement guides at the existing facilities or for the deployment of instruments for ongoing projects such as the European Spallation Source is briefly discussed

  11. Influence of SiO2 on conduction and relaxation mechanism of Li+ ions in binary network former lead silicate glasses

    International Nuclear Information System (INIS)

    Ion conducting glasses having composition 30Li2O·(70−x)PbO·xSiO2 were prepared by the normal melt quench technique. The compositional variations in density, molar volume and glass transition temperature confirm the dual role of PbO acting as a network modifying oxide as well as a network forming oxide. Conduction and relaxation mechanisms in these glasses were studied using impedance spectroscopy in the frequency range from 1 Hz to 7 MHz and in a temperature range below glass transition temperature. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency were extracted from the impedance spectra. Similar values of activation energy for dc conduction and for conductivity relaxation time indicate that the ions have to overcome the same energy barrier while conducting and relaxing. The increase in dc conductivity for silica rich compositions is attributed to the presence of mixed former effect in the studied glasses. The study of conductivity spectra reveals a transition from non-random to random hopping motion of lithium ions on successive replacement of PbO by SiO2 in glass matrix. The conduction and relaxation mechanism in the studied glasses are well explained with the concept of mismatch and relaxation (CMR) model

  12. Calcium-borosilicate glass-ceramics wasteforms to immobilize rare-earth oxide wastes from pyro-processing

    Science.gov (United States)

    Kim, Miae; Heo, Jong

    2015-12-01

    Glass-ceramics containing calcium neodymium(cerium) oxide silicate [Ca2Nd8-xCex(SiO4)6O2] crystals were fabricated for the immobilization of radioactive wastes that contain large portions of rare-earth ions. Controlled crystallization of alkali borosilicate glasses by heating at T ≥ 750 °C for 3 h formed hexagonal Ca-silicate crystals. Maximum lanthanide oxide waste loading was >26.8 wt.%. Ce and Nd ions were highly partitioned inside Ca-silicate crystals compared to the glass matrix; the rare-earth wastes are efficiently immobilized inside the crystalline phases. The concentrations of Ce and Nd ions released in a material characterization center-type 1 test were below the detection limit (0.1 ppb) of inductively coupled plasma mass spectroscopy. Normalized release values performed by a product consistency test were 2.64·10-6 g m-2 for Ce ion and 2.19·10-6 g m-2 for Nd ion. Results suggest that glass-ceramics containing calcium neodymium(cerium) silicate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing.

  13. Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

    OpenAIRE

    Watson, Timothy F; Atmeh, Amre R.; Sajini, Shara; Cook, Richard J.; Festy, Frederic

    2014-01-01

    Objective Since their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set i...

  14. Hydrothermal Synthesis of Metal Silicates

    Institute of Scientific and Technical Information of China (English)

    Lii Kwang-Hwa

    2004-01-01

    Organically templated metal phosphates have been extensively studied because of interesting structural chemistry and potential applications in catalysis. However, in most cases the organic templates cannot be removed without collapse of the frameworks. This is in contrast to the high thermal stability and extensive applications of zeolites in refinery and petrochemical processes.Therefore, studies have been directed to the synthesis of transition metal silicates to produce more stable frameworks. Our synthetic methods are twofold, namely mild hydrothermal reactions in Teflon-lined autoclaves at 100-200 ℃ using organic amines as templates and high-temperature,high-pressure hydrothermal reactions in gold ampoules contained in a high-pressure reaction vessel at ca. 550 ℃ and 150 Mpa using alkali metal cations as templates. In this presentation I will report the high-temperature, high-pressure hydrothermal synthesis, crystal structures, and solid-state NMR spectroscopy of a number of new silicates of indium, uranium, and transition metals.

  15. Alkali-ions diffusion, mullite formation, and crystals dissolution during sintering of porcelain bodies: Microstructural approach

    DEFF Research Database (Denmark)

    Leonelli, C.; Kamseu, E.; Boccaccini, Dino;

    2009-01-01

    The effect of alkali-silicate glassy matrix as replacement for feldspar in soft and hard porcelain compositions was studied. SEM and X-ray diffraction analysis were used to evidence phase evolution. For each composition, the influence of soaking time was evaluated. The difference in chemical...... to hard porcelain. Replacing the feldspar by alkali-silicate glassy matrices with similar chemical composition, the amount of secondary mullite and mechanical properties increased in both soft and hard compositions....

  16. The effects of silicic acid, aluminate ion activity and hydrosilicate gel development on the dissolution rate of a simulated British Magnox waste glass

    International Nuclear Information System (INIS)

    The dissolution rate of a simulated Magnox waste glass has been investigated in single-pass flow-through experiments designed to investigate the role of Al and Si in the dissolution process. The results indicate that both Al and Si species suppress the rate of dissolution. These effects may be modeled using a combined Al/Si affinity term in a conventional glass dissolution rate law. Aluminium species may also play an inhibitory role when present at relatively high solution activities. In Si-rich alkaline media, the concentration of aluminium is controlled to very low levels by the development of secondary aluminosilicate phases. Removal of Al by secondary phase precipitation results in dissolved Al activities below that required to reach saturation with respect to the glass

  17. 氢氧化钠溶液对硼硅酸盐玻璃光学和润湿性能的影响%Influence of Sodium Hydroxide Solution on the Optical and Wetting Properties of Borate Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    孟祥曼; 王亮; 陈宇; 王波; 张永哲; 严辉

    2015-01-01

    To improve the optical and wetting properties of the boron silicate glass with lowcost, a thin layer of anti-reflection and self-cleaning properties was prepared by chemical etching method on glass surface. Chemical corrosion of glass after pretreatment with sodium hydroxide solution,scanning electron microscopy ( SEM) was used to observe the surface morphology of the glass before and after etching. By adjusting the concentration of etching solution, the variation trend of the transmittance and the contact angle of the glass surface were measured with the spectrophotometer and the contact angle meter. Results show that the micro groove is formed on the surface after etching by 0. 05 mol/L sodium hydroxide solution, the length is about 100 nm, the width is about 10 nm, and the distribution is uniform and the transmittance of the glass is up to 94. 85%, which is 4. 15% higher than that of the original substrate. The contact angle is reduced from 53. 13 ° to 3. 25 ° . The optical properties and the self-cleaning performanceof the glasshave been effectively improved.%为低成本提高硼硅酸盐玻璃光学和润湿性能,采用化学刻蚀法在玻璃表面制备具有减反和自清洁性能的薄层. 利用NaOH溶液对预处理后的玻璃进行化学刻蚀,采用扫描电镜( scanning electron microscopy,SEM)对刻蚀前后玻璃表面形貌进行了观察,通过调控刻蚀液浓度,分别采用分光光度计和接触角仪测量玻璃表面的透光率和接触角随浓度的变化趋势. 结果表明:经0. 05 mol/L的氢氧化钠溶液刻蚀后,在表面形成长约为100 nm、宽约为10 nm、分布比较均匀的细微沟槽,玻璃的透过率达94. 85%,比原始基片提高了4. 15%,接触角从53. 13°降至3. 25°,玻璃的光学性能和自清洁性能得到了有效的提高.

  18. Origin of hydrous alkali feldspar-silica intergrowth in spherulites from intra-plate A2-type rhyolites at the Jabal Shama, Saudi Arabia

    Science.gov (United States)

    Surour, Adel A.; El-Nisr, Said A.; Bakhsh, Rami A.

    2016-03-01

    Miocene rhyolites (19.2 ± 0.9 Ma) at the Jabal Shama in western Saudi Arabia represent an example of rift-related silicic volcanism that took place during the formation of the Red Sea. They mostly consist of tuffaceous varieties with distinct flow banding, and pea-sized spherulites, obsidian and perlitized rhyolite tuffs. Although they have the geochemical signature of A2-type rhyolites, these silicic rocks are not typically alkaline but alkali-calcic to calc-alkaline. They developed in a within-plate regime and possibly derived from a recycled mafic subducted slab in depleted sub-continental mantle beneath the western Arabian plate. The Jabal Shama rhyolites are younger in age than their Miocene counterparts in Yemen and Ethiopia. The Jabal Shama spherulites consist of hydrous alkali feldspar-silica radial intergrowths with an occasional brown glass nucleus. Carbonate- and glass-free spherulites give up to 4.45 wt% L.O.I. The hydrous nature of these silicates and the absence of magnetite in the spherulites is a strong indication of oxidizing conditions. The spherulites contain hydrous feldspars with up to ∼6 wt% H2O, and they develop by diffusion and devitrification of glass in the rhyolite tuff at ∼800 °C. Owing to higher undercooling due to supersaturation, the radial hydrous phases within spherulites might grow faster and led to coagulation. The polygonal contacts between spherulites and the ∼120° dihedral angle suggest solid-state modification and recrystallization as the process of devitrification proceeds as low as ∼300 °C. The sum of FeO + MgO is positively correlated with total alkalies along with magnetite oxidation in the matrix to Fe-oxyhydroxides, and to the incorporation of OH- into silicates within the spehrulites themselves. Structural H2O in glass of the Jabal Shama perlite (obsidian) is considerable (∼9-12 wt%) with 3.72-5.6 wt% L.O.I. of the whole-rock. The presence of deleterious silica impurities would lower the ore grade due to

  19. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates.

    Science.gov (United States)

    Pustovgar, Elizaveta; Sangodkar, Rahul P; Andreev, Andrey S; Palacios, Marta; Chmelka, Bradley F; Flatt, Robert J; d'Espinose de Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of (29)Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966

  20. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    Science.gov (United States)

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; D'Espinose de Lacaillerie, Jean-Baptiste

    2016-03-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.

  1. Performance of Straight Steel Fibres Reinforced Alkali Activated Concrete

    Science.gov (United States)

    Faris, Meor Ahmad; Bakri Abdullah, Mohd Mustafa Al; Nizar Ismail, Khairul; Muniandy, Ratnasamy; Putra Jaya, Ramadhansyah

    2016-06-01

    This paper focus on the performance of alkali activated concrete produced by using fly ash activated by sodium silicate and sodium hydroxide solutions. These alkali activated concrete were reinforced with straight steel fibres with different weight percentage starting from 0 % up to 5 %. Chemical composition of raw material in the production alkali activated concrete which is fly ash was first identified by using X-ray fluorescence. Results reveal there have an effect of straight steel fibres inclusion to the alkali activated concrete. Highest compressive strength of alkali activated concrete which is 67.72 MPa was obtained when 3 % of straight fibres were added. As well as flexural strength, highest flexural strength which is 6.78 MPa was obtained at 3 % of straight steel fibres inclusions.

  2. Milk-alkali syndrome

    Science.gov (United States)

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

  3. Silicate-salt(sulfate) liquid immiscibility: a study of melt inclusions in minerals of the Mushugai-Khuduk carbonatite-bearing complex ( southern Mongolia )%硅酸盐-盐(硫酸盐)流体不混溶:蒙古南部Mushugai-Khuduk含火成碳酸岩杂岩体矿物中的熔体包裹体研究

    Institute of Scientific and Technical Information of China (English)

    Irina A.Andreeva; Vyacheslav I.Kovalenko; Vladimir B.Naumov

    2007-01-01

    Crystalline and melt inclusions were studied in garnet, diopside, potassium feldspar, and sphene from the garnet syenite porphyry of the carbonatite-bearing complex Mushugai-Khuduk, southern Mongolia. Phlogopite, clinopyroxene, albite, potassium feldspar, sphene, wollastonite, magnetite, Ca and Sr sulfates, fluorite, and apatite were identified among the crystalline inclusions.The melt inclusions were homogenized at 1010 ~ 1080℃ and analyzed on an electron microprobe. Silicate, salt, and combined silicatesalt melt inclusions were found. Silicate melts show considerable variations in SiO2 concentration (56 to 66wt% ), high Na2O + K2O(up to 17wt% ), and elevated Zr, F, and Cl contents. In terms of bulk rock chemistry, the silicate melts are alkali syenites. During thermometric experiments, salt melt inclusions quenched into homogeneous glasses of predominantly sulfate compositions containing no more than 1.3wt% SiO2. These melts are enriched in alkalis, Ba, Sr, P, F, and Cl. The investigation of the silicate and salt melt inclusions in minerals of the garnet syenite porphyries indicate that these rocks were formed under influence of the processes of crystallization differentiation and magma separation into immiscible silicate and salt (sulfate)liquids.

  4. Effect of copper-doped silicate 13-93 bioactive glass scaffolds on the response of MC3T3-E1 cells in vitro and on bone regeneration and angiogenesis in rat calvarial defects in vivo.

    Science.gov (United States)

    Lin, Yinan; Xiao, Wei; Bal, B Sonny; Rahaman, Mohamed N

    2016-10-01

    The release of inorganic ions from biomaterials could provide an alternative approach to the use of growth factors for improving tissue healing. In the present study, the release of copper (Cu) ions from bioactive silicate (13-93) glass scaffolds on the response of cells in vitro and on bone regeneration and angiogenesis in vivo was studied. Scaffolds doped with varying concentrations of Cu (0-2.0wt.% CuO) were created with a grid-like microstructure by robotic deposition. When immersed in simulated body fluid in vitro, the Cu-doped scaffolds released Cu ions into the medium in a dose-dependent manner and converted partially to hydroxyapatite. The proliferation and alkaline phosphatase activity of pre-osteoblastic MC3T3-E1 cells cultured on the scaffolds were not affected by 0.4 and 0.8wt.% CuO in the glass but they were significantly reduced by 2.0wt.% CuO. The percent new bone that infiltrated the scaffolds implanted for 6weeks in rat calvarial defects (46±8%) was not significantly affected by 0.4 or 0.8wt.% CuO in the glass whereas it was significantly inhibited (0.8±0.7%) in the scaffolds doped with 2.0wt.% CuO. The area of new blood vessels in the fibrous tissue that infiltrated the scaffolds increased with CuO content of the glass and was significantly higher for the scaffolds doped with 2.0wt.% CuO. Loading the scaffolds with bone morphogenetic protein-2 (1μg/defect) significantly enhanced bone infiltration and reduced fibrous tissue in the scaffolds. These results showed that doping the 13-93 glass scaffolds with up to 0.8wt.% CuO did not affect their biocompatibility whereas 2.0wt.% CuO was toxic to cells and detrimental to bone regeneration. PMID:27287141

  5. Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

    Directory of Open Access Journals (Sweden)

    Souag R.

    2014-01-01

    Full Text Available New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350°C, followed by a nucleation at 564°C, during 2 h, and a crystal growth at 1010°C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM coupled with energy dispersive X-ray (EDX analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

  6. Influence of Ga{sup 3+} ions on spectroscopic and dielectric features of multi component lithium lead boro bismuth silicate glasses doped with manganese ions

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh Babu, P.; Vijay, R. [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510, A.P. (India); Nageswara Rao, P. [Department of Physics, University College of Engg. and Technology, Acharya Nagarjuna University, Nagarjunanagar 522510, A.P. (India); Veeraiah, N. [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510, A.P. (India); Krishna Rao, D., E-mail: krdhanekula@yahoo.co.in [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510, A.P. (India)

    2013-11-15

    Graphical abstract: The plots between ε″(ω)ω vs. ε′(ω) and ε″(ω)/ω vs. ε′(ω) yield straight lines with slope 1/τ and τ, respectively. Considerable deviation from the straight line is observed in the high frequency region. Such deviation suggests spreading of relaxation times and this is attributed to the presence of multiple type of dipoles in the glass matrix. Variation of the parameters ωε″(ω) and ε″(ω)/ω with ε′(ω) of glass Li{sub 2}O–PbO–B{sub 2}O{sub 3}–SiO{sub 2}–Bi{sub 2}O{sub 3}–MnO multi-component glasses mixed with 2.0 mol% of Ga{sub 2}O{sub 3} measured at 373 K. - Highlights: • A series of Li{sub 2}O–PbO–B{sub 2}O{sub 3}–SiO{sub 2}–Bi{sub 2}O{sub 3}–MnO:Ga{sub 2}O{sub 3} glasses have been synthesized. • A variety of spectroscopic and dielectric properties have been investigated. • Analysis of the results indicated that glasses with below 3.0 mol% Ga{sub 2}O{sub 3} are good conducting materials. - Abstract: Multi-component glasses of the chemical composition 19.5Li{sub 2}O–20PbO–20B{sub 2}O{sub 3}–30SiO–(10 − x)Bi{sub 2}O{sub 3}–0.5MnO:xGa{sub 2}O{sub 3} with 0 ≤ x ≤ 5.0 have been synthesized. Spectroscopic (optical absorption, IR, Raman and ESR) and dielectric properties were investigated. Optical absorption and ESR spectral studies have indicated that managanese ions do exist in Mn{sup 3+} state in addition to Mn{sup 2+} state in the samples containing low concentration of Ga{sub 2}O{sub 3}. The IR and Raman studies indicated increasing degree of disorder in the glass network with the concentration of Ga{sub 2}O{sub 3} up to 3.0 mol%. The dielectric constant, loss and ac conductivity are observed to increase with the concentration of Ga{sub 2}O{sub 3} up to 3.0 mol%. The quantitative analysis of the results of dielectric properties has indicated an increase in the insulating strength of the glasses as the concentration of Ga{sub 2}O{sub 3} is raised beyond 3.0 mol%. This has

  7. DFT modeling of 45S5 and 77S soda-lime phospho-silicate glass surfaces: clues on different bioactivity mechanism.

    Science.gov (United States)

    Berardo, Enrico; Pedone, Alfonso; Ugliengo, Piero; Corno, Marta

    2013-05-14

    The reactivity of bioglasses, which is related to the dissolution of cations and orthosilicate groups in the physiological fluid, strongly depends on the key structural features present at the glass surfaces. On the basis of the composition and the synthetic routes employed to make the glass, surfaces with very different characteristics and thus presenting different mechanisms of dissolution can be observed. In this paper, the surface structures of two very different bioglass compositions, namely 45S5 (46.1 SiO2, 24.4 Na2O, 26.9 CaO, and 2.6 P2O5 mol %) and 77S (80.0 SiO2, 16.0 CaO, and 4.0 P2O5 mol %), have been investigated by means of periodic DFT calculations based on a PBE functional and localized Gaussian basis set as encoded in the CRYSTAL code. Our calculations show that the two glass surfaces differ by the relative amount of key structural sites such as NBOs, exposed ions, orthosilicate units, and small rings. We have demonstrated how the number of these sites affects the surface stability and reactivity (bioactivity). PMID:23594027

  8. Heavy ion bombardment of silicates and nitrides

    International Nuclear Information System (INIS)

    Several silicates, including α-quartz, zirconium silicate, thorium silicate, LiAlSiO4, a silicate glass and several nitrides, α and β Si3N4, AlN, ZrN as well as Si2N2O and ThO2, have been irradiated by 1019 to 1021 Krypton (3 MeV) ions/m2. The damaged powders of original particle size less than 5 μm, have been examined by x-ray diffraction and electron microscope methods. The silicates and Si2N2O become non-crystalline by 10 x 1019 ions/m2. The particles change shape, extending and bloating under prolonged irradiations of the order of 100 x 1019 ions/m2. Silicate glass also undergoes this irradiation creep process. The nitrides and ThO2 behave quite differently and even at fluences of 200 x 1019 x ions/m-2 the powders remain crystalline, retaining relatively sharp edges to the particles without exhibiting irradiation creep. This difference in behavior can be related to the nature of the framework crystal structures, flexible for the silicates with variable bond angles, rigid for the nitrides with fixed bond angles. This may explain the behavior of radioactive minerals not found in a metamict condition. (author)

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

    Science.gov (United States)

    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 (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 performance, composition was also found to be important. The initial stoichiometry of the bulk mixture was maintained fairly closely, especially in mixtures made with fine

  10. FT-IR and 29 Si-NMR for evaluating aluminium silicate precursors for geopolymers

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Fischer, H.R.; Verkuijlen, M.H.W.; Eck, E.R.H.

    2014-01-01

    Geopolymers are systems of inorganic binders that can be used for sustainable, cementless concrete and are formed by alkali activation of an aluminium–silicate precursor (often secondary resources like fly ash or slag). The type of aluminium– silicate precursor and its potential variations within on

  11. Rapid quantitative determination of major and trace elements in silicate rocks and soils employing fused glass discs using wavelength dispersive X-ray fluorescence spectrometry

    Science.gov (United States)

    Krishna, A. Keshav; Khanna, Tarun C.; Mohan, K. Rama

    2016-08-01

    This paper introduces a calibration procedure and provides the data achieved for accuracy, precision, reproducibility and the detection limits for major (Si, Al, Fe, Mn, Mg, Ca, Na, K, Ti, P) and trace (Ba, Cr, Cu, Hf, La, Nb, Ni, Pb, Rb, Sr, Ta, Th, U, Y, Zn, Zr) elements in the routine analysis of geological and environmental samples. Forty-two rock and soil reference materials were used to calibrate and evaluate the analytical method using a sequential wavelength dispersive X-ray fluorescence spectrometer. Samples were prepared as fused glass discs and analysis performed with a total measuring time of thirty-one minutes. Another set of twelve independent reference materials were analyzed for the evaluation of accuracy. The detection limits and accuracy obtained for the trace elements (1-2 mg/kg) are adequate both for geochemical exploration and environmental studies. The fitness for purpose of the results was also evaluated by the quality criteria test proposed by the International Global Geochemical Mapping Program (IGCP) from which it can be deduced that the method is adequate considering geochemical mapping application and accuracy obtained is within the expected interval of certified values in most cases.

  12. Cd{sub 1−x}Mn{sub x}Te ultrasmall quantum dots growth in a silicate glass matrix by the fusion method

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Noelio Oliveira; Lima Fernandes, Guilherme de; Almeida Silva, Anielle Christine [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38408-100 Uberlândia, MG (Brazil); Baffa, Oswaldo; Gómez, Jorge Antônio [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP (Brazil)

    2014-09-29

    In this study, we synthesized Cd{sub 1−x}Mn{sub x}Te ultrasmall quantum dots (USQDs) in SiO{sub 2}-Na{sub 2}CO{sub 3}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3} glass system using the fusion method. Growth of these Cd{sub 1−x}Mn{sub x}Te USQDs was confirmed by optical absorption, atomic force microscopy (AFM), magnetic force microscopy (MFM), scanning transmission electron microscopy (TEM), and electron paramagnetic resonance (EPR) measurements. The blueshift of absorption transition with increasing manganese concentration gives evidence of incorporation of manganese ions (Mn{sup 2+}) in CdTe USQDs. AFM, TEM, and MFM confirmed, respectively, the formation of high quality Cd{sub 1−x}Mn{sub x}Te USQDs with uniformly distributed size and magnetic phases. Furthermore, EPR spectra showed six lines associated to the S = 5/2 spin half-filled d-state, characteristic of Mn{sup 2+}, and confirmed that Mn{sup 2+} are located in the sites core and surface of the CdTe USQD. Therefore, synthesis of high quality Cd{sub 1−x}Mn{sub x}Te USQDs may allow the control of optical and magnetic properties.

  13. Carbonatite-silicate immiscible melt inclusion in lamprophyre from Kutch, western India: Implication for plume-lithosphere interaction and initiation of Deccan Trap magmatism

    Science.gov (United States)

    Ray, Arijit; Paul, Dalim Kumar; Sen, Gautam; Biswas, Sanjib Kumar

    2014-05-01

    Kutch province of western India has undergone repeated rifting and marine transgression events from late Triassic to the late Cretaceous. Magmatic rocks occur in profusion in Kutch Basin. The southern part is characterized by occurrences of thick flows of tholeiitic basalt of Deccan Trap affinity, central part of Kutch Basin has numerous volcanic plugs of alkali basalt which is also considered as member of Deccan Trap, contain thin, discoidal mantle xenoliths of spinel lherzolite and wehrlite composition. Northern Kutch is dominated by suite of alkaline magmatic rocks similar to magmatic rocks of continental rift zone. The alkaline suite contains alkali pyroxenite, theralite, teschenite, basanite, nepheline syenite and kaersutite bearing lamprophyre (Ray et al., 2006, Das et al., 2007, Paul et al., 2008). The newly discovered east-west trending lamprophyre dyke swarm of northern Kutch (Pachham Island) is camptonite in composition and contains kaersutite phenocrysts in large proportion. These kaersutite phencrysts contain immscible melt/glass phases as melt inclusions. The lamprophyre yields an age of ca. 67 Ma.by Ar-Ar method (Sen et al., 2014 in press) synchronous with alkali basalt of central Kutch. The melt inclusions are fundamentally of two types - calciocarbonatite and alkaline silicate melts. We found sphene within carbonatitic melt and the rare mineral rhonite in silicate melt. Petrographic evidence indicates that carbonatite melt always occurs within alkali silicate melt as immiscible fraction. These carbonatite melts are extremely rich in CaCO3 (upto 95%) which contradicts the experimental results of carbonate melt composition (upto 80% CaCO3) in silicate-carbonate immiscible melt pair by Lee and Wyllie. The abundance of wehrlite xenoliths over lherzolite in alkali basalt, petrographic evidence of orthopyroxene to clinopyroxene transformation in wehrlite xenoliths, occurrence of calcite vein in mantle xenoliths indicate carbonatite metasomatism of spinel

  14. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    NARCIS (Netherlands)

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable

  15. Alkali-activated cementitious materials: Mechanisms, microstructure and properties

    Science.gov (United States)

    Jiang, Weimin

    The goal of this study was to examine the activation reaction, microstructure, properties, identify the mechanisms of activation, and achieve an enhanced understanding of activation processes occurring during the synthesis of alkali activated cementitious materials (AAC). The discussions classify the following categories. (1) alkali activated slag cement; (2) alkali activated portland-slag cement; (3) alkali activated fly ash-slag cement; (4) alkali activated pozzolana-lime cement; (5) alkali activated pozzolana cement. The activators involved are NaOH, KOH; Nasb2SOsb4;\\ Nasb2COsb3;\\ CaSOsb4, and soluble silicate of sodium and potassium. The effect of alkali activation on the microstructure of these materials were analyzed at the micro-nanometer scale by SEM, EDS, ESEM, and TEM. Also sp{29}Si and sp{27}Al MAS-NMR, IR, Raman, TGA, and DTA were performed to characterize the phase in these systems. Slag, fly ash, silica fume, as well as blended cements containing mixtures of these and other components were characterized. A set of ordinary portland cement paste samples served as a control. This study confirmed that AAC materials have great potential because they could generate very early high strength, greater durability and high performance. Among the benefits to be derived from this research is a better understanding of the factors that control concrete properties when using AAC materials, and by controlling the chemistry and processing to produce desired microstructures and properties, as well as their durability.

  16. Irradiations effects on the structure of boro-silicated glasses: long term behaviour of nuclear waste glassy matrices; Effets d'irradiations sur la structure de verres borosilicates - comportement a long terme des matrices vitreuses de stockage des dechets nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Bonfils, J. de

    2007-09-15

    This work deals with the long term behaviour of R7T7-type nuclear waste glasses and more particularly of non-active boro-silicated glasses made up of 3 or 5 oxides. Radioactivity of active glasses is simulated by multi energies ions implantations which reproduce the same defects. The damages due to the alpha particles are simulated by helium ions implantations and those corresponding to the recoil nucleus are obtained with gold ions ones. Minor actinides, stemming from the used fuel, is simulated by trivalent rare-earths (Eu{sup 3+} and Nd{sup 3+}). In a first part, we have shown by macroscopic experiments (Vickers hardness - swelling) and optical spectroscopies (Raman - ATR-IR) that the structure of the glassy matrices is modified under implantations until a dose of 2,3.10{sup 13} at.cm{sup -2}, which corresponds to a R7T7 storage time estimated at 300 years. Beyond this dose, no additional modifications have been observed. The second part concerns the local environment of the rare-earth ions in glasses. Two different environments were found and identified as follows: one is a silicate rich one and the other is attributed to a borate rich one. (author)

  17. Cementitious binders from activated stainless steel refining slag and the effect of alkali solutions.

    Science.gov (United States)

    Salman, Muhammad; Cizer, Özlem; Pontikes, Yiannis; Snellings, Ruben; Vandewalle, Lucie; Blanpain, Bart; Van Balen, Koen

    2015-04-01

    With an aim of producing high value cementitious binder, stainless steel refining slag containing a high amount of CaO in γ-dicalcium silicate form was activated with NaOH and Na-silicate as well as KOH and K-silicate solutions, followed by steam curing at 80 °C. Higher levels of alkali-silicate in the activating solution resulted in higher cumulative heat suggesting accelerated reaction kinetics. With respect to compressive strength, higher levels of alkali silicate resulted in higher strength and the mortars with Na activator were found to have higher early strength than the ones with K activator. The long term strength was found to be similar, regardless of the alkali metal. Thermogravimetric, QXRD and FTIR analyses showed an increase in the amount of reaction products (C-S-H type) over time, further confirming the reactivity of the crystalline slag. Batch leaching results showed lower leaching of heavy metals and metalloids with K activator compared to the Na activator. These results demonstrate that the alkali type and the ratio of hydroxide to silicates have a significant impact on the hydration and mechanical strength development of the stainless steel slag. The above findings can aid in the recycling and valorization of these type of slags which otherwise end up landfilled. PMID:25577317

  18. Fine Structure of Ag-Cu Bimetallic Nanoparticles in Silicate Glass%硅酸盐玻璃中银铜双金属纳米颗粒的精细结构

    Institute of Scientific and Technical Information of China (English)

    赵建富; 杨修春; 黄敏; 姜政; 黄宇营

    2012-01-01

    采用离子交换结合热处理方法制备了银铜纳米颗粒/硅酸盐玻璃复合材料。利用扩展X射线吸收精细结构谱和紫外-可见吸收光谱对复合材料中银铜纳米晶的精细结构进行了表征和分析。结果表明:玻璃中银铜纳米颗粒各自分散在玻璃基质中;银纳米颗粒的Ag-Ag键长由于制备过程中产生的张应力使标准银箔发生了膨胀;铜纳米颗粒表面的Cu-O配位数由于Cu-Cu配位的出现而降低,且Cu-Cu配位数远小于标准铜箔中Cu-Cu的配位数,其键长也发生了收缩。%Bimetallic Ag-Cu nano-particles were prepared via ion-exchange and subsequently thermal treatment. The formation process and local structure of Ag-Cu nano-particles in composite materials were characterized by extended X-ray absorption fine structure technique and ultraviolet-visible absorption spectroscopy, respectively. The results indicate that Ag and Cu nano-particles exist in the silicate glass. Compared to the corresponding value of Ag foil, the nearest-neighboring Ag-Ag distance expanded due to the tensile stress in the synthesis process. The Cu-Cu coordination appeared, inducing a decrease of the Cu-O coordination number. The Cu-Cu coordination number was smaller than the corresponding value of Cu foil, and the Cu-Cu distance contracted compared to the corresponding value of Cu foil.

  19. Reaction sintered glass: a durable matrix for spinel-forming nuclear waste compositions

    International Nuclear Information System (INIS)

    Glass formation by reaction sintering under isostatic pressure is an innovative process to vitrify refractory-rich high-level radioactive waste. We used a typical defense waste composition, containing spinel-forming components such as ∼4 wt% of Cr2O3, ∼23 wt% Al2O3, ∼13 wt% Fe2O3, and ∼9 wt% UO2, with CeO2 simulating UO2. Reaction sintered silicate glasses with waste loading up to 45 wt% were prepared within three hours, by hot pressing at 800 deg. C. The glass former was amorphous silica. Simulated waste was added as calcined oxides. The reaction sintered glass samples were characterized using scanning and analytical electron microscopy. The results show that extensive reaction sintering took place and a continuous glass phase formed. Waste components such as Na2O, CaO, MnO2, and Fe2O3, dissolved completely in the continuous glass phase. Cr2O3, Al2O3, and CeO2 were only partially dissolved due to incomplete dissolution (Al2O3) or super-saturation and reprecipitation (Cr2O3 and CeO2). The precipitation mechanism is related to a time dependent alkali content in the developing glass phase. Short-term corrosion tests in water showed that the glasses are chemically more durable than melted nuclear waste glasses. Based on hydration energies calculations, the long-term chemical durability of our reaction sintered glasses is expected to be comparable to that of rhyolitic and tektite glasses

  20. Effect of different glasses in glass bonded zeolite

    International Nuclear Information System (INIS)

    A mineral waste form has been developed for chloride waste salt generated during the pyrochemical treatment of spent nuclear fuel. The waste form consists of salt-occluded zeolite powders bound within a glass matrix. The zeolite contains the salt and immobilizes the fission products. The zeolite powders are hot pressed to form a mechanically stable, durable glass bonded zeolite. Further development of glass bonded zeolite as a waste form requires an understanding of the interaction between the glass and the zeolite. Properties of the glass that enhance binding and durability of the glass bonded zeolite need to be identified. Three types of glass, boroaluminosilicate, soda-lime silicate, and high silica glasses, have a range of properties and are now being investigated. Each glass was hot pressed by itself and with an equal amount of zeolite. MCC-1 leach tests were run on both. Soda-lime silicate and high silica glasses did not give a durable glass bonded zeolite. Boroaluminosilicate glasses rich in alkaline earths did bind the zeolite and gave a durable glass bonded zeolite. Scanning electron micrographs suggest that the boroaluminosilicate glasses wetted the zeolite powders better than the other glasses. Development of the glass bonded zeolite as a waste form for chloride waste salt is continuing

  1. The effect of melt composition on the partitioning of oxidized sulfur between silicate melts and magmatic volatiles

    Science.gov (United States)

    Zajacz, Zoltán

    2015-06-01

    Experiments were conducted at 500 MPa and 1240 °C in a piston cylinder apparatus to assess the effect of melt composition on the melt/volatile partition coefficient of sulfur (DSmelt/volatile) , which was used as a measure of the silicate melt's capacity to dissolve oxidized sulfur species. Iron-free, three- and four-component silicate melts were equilibrated with H2O-S fluids with sulfur concentrations ⩽2 mol% at an oxygen fugacity imposed by the Re-ReO2 buffer (1.4 log units above the Ni-NiO buffer). At these conditions, SO2 (S4+) is predicted to be the dominant sulfur species in the volatile phase and sulfate (S6+) is the dominant sulfur species in the silicate melt. The values of DSmelt /volatile were calculated by mass balance. The results show that DSmelt /volatile values increase exponentially with decreasing the degree of polymerization of the silicate melt structure. For example, in calcium-aluminosilicate melts, DSmelt /volatile changes from 0.005 to 0.3 as the degree of melt polymerization changes from the equivalent of a rhyolite to the equivalent of a basalt. At a constant degree of melt polymerization, DSmelt /volatile in equilibrium with sodium-aluminosilicate (NAS) melts is more than an order of magnitude higher than in equilibrium with calcium-aluminosilicate (CAS) melts, and more than two orders of magnitude higher than in equilibrium with magnesium-aluminosilicate (MAS) melts. The value of DSmelt /volatile changes from 0.014 in MAS glasses to 3.4 in NAS glasses for the most depolymerized compositions in each series. Potassium has a similar effect on sulfate dissolution to that of Na. The variation of DSmelt /volatile in equilibrium with various calcium-sodium aluminosilicate (CNAS), magnesium-sodium aluminosilicate (MNAS) and magnesium-potassium aluminosilicate (MKAS) melts indicates that alkalis are only available for sulfate complexation when they are present in excess compared to the required amount to charge balance for the Si4+ to Al3

  2. Structural Investigation of Alkali Activated Clay Minerals for Application in Water Treatment Systems

    Science.gov (United States)

    Bumanis, G.; Bajare, D.; Dembovska, L.

    2015-11-01

    Alkali activation technology can be applied for a wide range of alumo-silicates to produce innovative materials with various areas of application. Most researches focuse on the application of alumo-silicate materials in building industry as cement binder replacement to produce mortar and concrete [1]. However, alkali activation technology offers high potential also in biotechnologies [2]. In the processes where certain pH level, especially alkaline environment, must be ensured, alkali activated materials can be applied. One of such fields is water treatment systems where high level pH (up to pH 10.5) ensures efficient removal of water pollutants such as manganese [3]. Previous investigations had shown that alkali activation technology can be applied to calcined clay powder and aluminium scrap recycling waste as a foam forming agent to create porous alkali activated materials. This investigation focuses on the structural investigation of calcined kaolin and illite clay alkali activation processes. Chemical and mineralogical composition of both clays were determined and structural investigation of alkali activated materials was made by using XRD, DTA, FTIR analysis; the microstructure of hardened specimens was observed by SEM. Physical properties of the obtained material were determined. Investigation indicates the essential role of chemical composition of the clay used in the alkali activation process, and potential use of the obtained material in water treatment systems.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kurtis, K.E.; Monteiro, P.J.M. [Univ. of California, Berkeley, CA (United States); Brown, J.T.; Meyer-Ilse, W. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

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

  4. Photoactive transparent nano-crystalline glass-ceramic for remazole red dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gad-Allah, Tarek A., E-mail: tareqabdelshafy@yahoo.ca [Water Pollution Research Department, National Research Centre, Cairo 12311 (Egypt); Margha, Fatma H. [Department of Glass Research, National Research Centre, Cairo 12311 (Egypt)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Preparation and characterization of novel transparent nanocrystalline glass-ceramic. ► Precipitation of photoactive phases by using controlled heat-treatment. ► Conservation of transparency along with photoactivity. ► Using the prepared nanocrystalline glass-ceramic in water purification. -- Abstract: Transparent glass ceramic material was prepared from alkali-borosilicate glass containing titania by proper heat treatment scheme. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, transmission electron microscope, selected area electron diffraction and UV–visible spectroscopy. The applied heat treatment program allowed the crystallization of nano-crystalline anatase, rutile, barium titanate, titanium borate and silicate phases while maintaining the transparency. The precipitated nano-crystalline anatase and rutile phases were responsible for the observed high photocatalytic activity of the prepared samples. Samples of 24.29 and 32.39 TiO{sub 2} wt% showed better efficiency for the decolorization of remazole red dye compared with commercial-TiO{sub 2} used in preparation of glass-ceramic. The reuse of prepared glass-ceramic photocatalyst with nearly same efficiency for different times was also proved.

  5. Effect of the Composite of Natural Zeolite and Fly Ash on Alkali-Silica Reaction

    Institute of Scientific and Technical Information of China (English)

    FENG Xiao-xin; FENG Nai-qian; HAN Dong

    2003-01-01

    The effect of the composite of natural zeolite and fly ash on alkali-silica reaction ( ASR ) was studied with natural alkali-reactive aggregate and quartz glass aggregate respecthvely. The expansive experiment of mortar bar and concrete prism was completed. The results show that ASR can be suppressed effectively by the composite of natural zeolite and fly ash.

  6. Effect of ZnO and CaO on Alkali Borosilicate Glass Waste-form Immobilizing Simulated Mixed HLW%ZnO 和 CaO对模拟高放废液硅酸盐玻璃固化体性能的影响研究

    Institute of Scientific and Technical Information of China (English)

    张华; N.C.Hyatt; J.R.Stevens; R.Hand

    2015-01-01

    针对有些高放废液含有较多Fe、Cr、Ni过渡金属元素,在玻璃固化工艺过程中易于形成晶体,导致熔融玻璃体的黏度增加、化学稳定性变差以及工艺过程中易出现出料口堵塞等问题,研究了废物包容量为15%和20%、添加ZnO (5.6%)和CaO (1.75%)的配方对形成的4种玻璃固化体的物理性能(密度、硬度、断裂韧性)、化学性能(产品一致性测试和蒸汽腐蚀测试)和结构(X射线衍射析晶分析、拉曼光谱分析)的影响。研究分析显示,提高废物包容量至20%以及添加ZnO和CaO均可促进硼硅酸盐玻璃固化体网络结构的稳定性和化学稳定性,并增强玻璃体的密度,提高硬度;但玻璃固化体的高温黏度升高,断裂韧性下降。%Since the transit metals ,such as Fe ,Cr and Ni ,contained in some kinds of mixed HLW ,can likely to form crystal ,increase the melt viscosity ,destroy the chemi‐cal durability and block the discharge port .T he results obtained from investigating four glass waste‐forms ,including the alkali borosilicate glass matrix and alkali borosilicate glass matrix doped with 5.6% ZnO and 1.75% CaO in base matrixes ,immobilizing the simulated mixed HLW with 15% and 20% waste loadings aiming to determinate the effect of ZnO on the alkali borosilicate glass chemical durability with waste loading increasing ,were presented in this paper .Glass samples were characterized with XRD and Raman spectroscopy .The chemical durability was investigated using the standard protocols PCT and VHT .The XRD analysis results show that spinel crystal appears and grows in glass samples at the waste loading in 20% without ZnO addition and waste loading in 15% and 20% added ZnO .T he Raman spectroscopy analysis results indicate that ZnO and CaO can enhance the glass network connective ,and the chemical durability test results display that the addition of ZnO and CaO can improve the short term

  7. Alkali activated fly ash binders. A comparative study between sodium and potassium activators

    OpenAIRE

    Criado, M.; Palomo, A.; Fernández-Jiménez, A.

    2006-01-01

    This paper shows the effect of the nature of some alkaline activators in the microstructural development of thermal-alkali activated f/y ash systems. The alkaline compounds employed in this investigation were: NaOH, KOH, Na2C03, K2C03, sodium silicate and potassium silicate. Results confirm that the main reaction product of the activation process (throughout the studied systems) is the amorphous alkaline aluminosilicate gel with a three-dimensional structure already observed in earlier resea...

  8. Decalcification resistance of alkali-activated slag

    Energy Technology Data Exchange (ETDEWEB)

    Komljenovic, Miroslav M., E-mail: miroslav.komljenovic@imsi.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bascarevic, Zvezdana, E-mail: zvezdana@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Marjanovic, Natasa, E-mail: natasa@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia); Nikolic, Violeta, E-mail: violeta@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11030 Belgrade (Serbia)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer The effects of decalcification on properties of alkali-activated slag were studied. Black-Right-Pointing-Pointer Decalcification was performed by concentrated NH{sub 4}NO{sub 3} solution (accelerated test). Black-Right-Pointing-Pointer Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Black-Right-Pointing-Pointer Decalcification led to strength decrease and noticeable structural changes. Black-Right-Pointing-Pointer Alkali-activated slag showed significantly higher resistance to decalcification. - Abstract: This paper analyses the effects of decalcification in concentrated 6 M NH{sub 4}NO{sub 3} solution on mechanical and microstructural properties of alkali-activated slag (AAS). Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Decalcification process led to a decrease in strength, both in AAS and in CEM II, and this effect was more pronounced in CEM II. The decrease in strength was explicitly related to the decrease in Ca/Si atomic ratio of C-S-H gel. A very low ratio of Ca/Si {approx}0.3 in AAS was the consequence of coexistence of C-S-H(I) gel and silica gel. During decalcification of AAS almost complete leaching of sodium and tetrahedral aluminum from C-S-H(I) gel also took place. AAS showed significantly higher resistance to decalcification in relation to the benchmark CEM II due to the absence of portlandite, high level of polymerization of silicate chains, low level of aluminum for silicon substitution in the structure of C-S-H(I), and the formation of protective layer of polymerized silica gel during decalcification process. In stabilization/solidification processes alkali-activated slag represents a more promising solution than Portland-slag cement due to significantly higher resistance to decalcification.

  9. Analysis of early medieval glass beads – Glass in the transition period

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Smit, Ziga, E-mail: ziga.smit@ijs.si [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia); Jozef Stefan Institute, Jamova 39, P.O.B. 3000, SI-1001 Ljubljana (Slovenia); Knific, Timotej [National Museum of Slovenia, Presernova 20, SI-1000 Ljubljana (Slovenia); Jezersek, David [Jozef Stefan Institute, Jamova 39, P.O.B. 3000, SI-1001 Ljubljana (Slovenia); Istenic, Janka [National Museum of Slovenia, Presernova 20, SI-1000 Ljubljana (Slovenia)

    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.

  11. Nouvelle approche pour le suivi de la réactivité de phases SiO2 soumises à la Réaction Alcali Silice (RAS New approach for monitoring the reactivity of SiO2 phases subject to Alkali Silica Reaction (SAR

    Directory of Open Access Journals (Sweden)

    Harfouche M.

    2012-09-01

    Full Text Available Nous avons suivi- au moyen de la microscopie électronique à balayage environnementale (MEBE la diffraction X et la spectroscopie d’absorption des rayons X sous rayonnement synchrotron (XANES- la réactivité de certaines phases SiO2 lors du processus de la Réaction Alcali Silice (RAS. Cette réactivité est étroitement liée à la structure locale autour des atomes de silicium ainsi qu’à la présence d’impuretés comme le fer. Dans le cas du silex brut, la raie blanche du seuil K du fer ressemble davantage à celle de Fe3O4 ce qui permet de déduire la présence d’un mélange de Fe2+/Fe3+ dans le silex de départ. Après réaction, l’allure du spectre d’absorption des rayons X au seuil K du fer du silex est conservée avec un léger déplacement de la raie blanche vers les hautes énergies. Cette augmentation montre une prédominance de la valence Fe3+ au détriment de la valence Fe2+. Les résultats montrent que le fer participe à la stabilisation de la structure des phases formées. Cette étude peut être étendue à d’autres éléments traces présents dans la structure du silex de départ. In this study the reactivity of some SiO2 phases under Alkali Silica Reaction (RAS process is followed, using the environmental scanning electron microscopy (ESEM X-ray diffraction and absorption spectroscopy X-ray synchrotron radiation (XANES. This reactivity is closely related to the local structure around the silicon atoms and the presence of impurities such as iron. In the case of flint raw skate white iron K line is more like that of Fe3O4 which allows to deduce the presence of a mixture of Fe2+ / Fe3+ in the flint to start. After reaction, the shape of the spectrum of X-ray absorption K edge of iron in the flint is retained with a slight displacement of the white stripe to high energies. This increase shows a predominance of the valence Fe3+ at the expense of Fe2+ valence. The results show that iron is involved in stabilizing the

  12. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  13. Methods of recovering alkali metals

    Science.gov (United States)

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

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

  14. Spectroscopic study of biologically active glasses

    Science.gov (United States)

    Szumera, M.; Wacławska, I.; Mozgawa, W.; Sitarz, M.

    2005-06-01

    It is known that the chemical activity phenomenon is characteristic for some inorganic glasses and they are able to participate in biological processes of living organisms (plants, animals and human bodies). An example here is the selective removal of silicate-phosphate glass components under the influence of biological solutions, which has been applied in designing glasses acting as ecological fertilizers of controlled release rate of the nutrients for plants. The structure of model silicate-phosphate glasses containing the different amounts of the glass network formers, i.e. Ca 2+ and Mg 2+, as a binding components were studied. These elements besides other are indispensable of the normal growth of plants. In order to establish the function and position occupied by the particular components in the glass structure, the glasses were examined by FTIR spectroscopy (with spectra decomposition) and XRD methods. It has been found that the increasing amount of MgO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes systematically from a structure of the cristobalite type to a structure corresponding to forsterite type. Whilst the increasing content of CaO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes from a structure typical for cristobalite through one similar to the structure of calcium orthophosphate, to a structure corresponding to calcium silicates. The changing character of domains structure is the reason of different chemical activity of glasses.

  15. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  16. Cumulate Fragments in Silicic Ignimbrites

    Science.gov (United States)

    Bachmann, O.; Ellis, B. S.; Wolff, J.

    2014-12-01

    Increasingly, studies are concluding that silicic ignimbrites are the result of the amalgamation of multiple discrete magma batches. Yet the existence of discrete batches presents a conundrum for magma generation and storage; if silicic magma batches are not generated nearly in situ in the upper crust, they must traverse, and reside within, a thermally hostile environment with large temperature gradients, resulting in low survivability in their shallow magmatic hearths. The Snake River Plain (Idaho, USA) is a type example of this 'multi-batch' assembly with ignimbrites containing multiple populations of pyroxene crystals, glass shards, and crystal aggregates. The ubiquitous crystal aggregates hint at a mechanism to facilitate the existence of multiple, relatively small batches of rhyolite in the upper crust. These aggregates contain the same plagioclase, pyroxene, and oxide mineral compositions as single phenocrysts of the same minerals in their host rocks, but they have significantly less silicic bulk compositions and lack quartz and sanidine, which occur as single phenocrysts in the deposits. This implies significant crystallization followed by melt extraction from mushy reservoir margins. The extracted melt then continues to evolve (crystallizing sanidine and quartz) while the melt-depleted margins provide an increasingly rigid and refractory network segregating the crystal-poor batches of magma. The hot, refractory, margins insulate the crystal-poor lenses, allowing (1) extended residence in the upper crust, and (2) preservation of chemical heterogeneities among batches. In contrast, systems that produce cumulates richer in low-temperature phases (quartz, K-feldspars, and/or biotite) favour remelting upon recharge, leading to less segregation of eruptible melt pockets and the formation of gradationally zoned ignimbrites. The occurrence of similar crystal aggregates from a variety of magmatic lineages suggests the generality of this process.

  17. "Low-Li2O" Frits: Selecting Glasses that Support the Melt Rate Studies and Challenge the Current Durability Model

    Energy Technology Data Exchange (ETDEWEB)

    Peeler, D. K.; Edwards, T. B.

    2005-07-30

    During the progressive development of the cold cap model (as it applies to a potential melt rate predictive tool), the formation of an Al-Li-silicate phase was identified as an intermediate reaction phase that could possibly hinder melt rate for SB4. To test this theory, six glasses were designed (using Frit 320's composition as the baseline) to maintain a constant 20 wt% sum of alkali content (in frit) by varying Na{sub 2}O to Li{sub 2}O ratios. The Li{sub 2}O concentration ranged from 8 wt% down to 0% in either 2% or 1% increments with the differences being accounted for by an increase in Na{sub 2}O concentration. Although the primary objective of the ''lower Li{sub 2}O'' frits was to evaluate the potential for melt rate improvements, assessments of durability (as measured by the Product Consistency Test (PCT)) were also performed. The results suggest that durable glasses can be produced with these ''lower Li{sub 2}O'' frits should it be necessary to pursue this option for improving melt rate. In addition to the series of glasses to support melt rate assessments, a series of frits were also developed to challenge the current durability model based on the limits proposed by Edwards et al. (2004). Although the ''new'' limits allow access into compositional regions of interest (i.e., higher alkali systems) which can improve melt rate and/or waste loading, there may still be ''additional'' conservatism. In this report, two series of glasses were developed to challenge the ''new'' durability limits for the SB4 system. In the first series, the total alkali of the Frit 320-based glasses (designed to support the melt rate program) was increased from 20 wt% to 21 wt% (in the frit), but the series also evaluated the possible impact of various Na{sub 2}O and Li{sub 2}O mass ratio differences. The second series pushed the alkali limit in the frit even further with frits

  18. SUMMARY OF 2010 DOE EM INTERNATIONAL PROGRAM STUDIES OF WASTE GLASS STRUCTURE AND PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Choi, A.; Marra, J.; Billings, A.

    2011-02-07

    Collaborative work between the Savannah River National Laboratory (SRNL) and SIA Radon in Russia was divided among three tasks for calendar year 2010. The first task focused on the study of simplified high level waste glass compositions with the objective of identifying the compositional drivers that lead to crystallization and poor chemical durability. The second task focused on detailed characterization of more complex waste glass compositions with unexpectedly poor chemical durabilities. The third task focused on determining the structure of select high level waste glasses made with varying frit compositions in order to improve models under development for predicting the melt rate of the Defense Waste Processing Facility (DWPF) glasses. The majority of these tasks were carried out at SIA Radon. Selection and fabrication of the glass compositions, along with chemical composition measurements and evaluations of durability were carried out at SRNL and are described in this report. SIA Radon provided three summary reports based on the outcome of the three tasks. These reports are included as appendices to this document. Briefly, the result of characterization of the Task 1 glasses may indicate that glass compositions where iron is predominantly tetrahedrally coordinated have more of a tendency to crystallize nepheline or nepheline-like phases. For the Task 2 glasses, the results suggested that the relatively low fraction of tetrahedrally coordinated boron and the relatively low concentrations of Al{sub 2}O{sub 3} available to form [BO{sub 4/2}]{sup -}Me{sup +} and [AlO{sub 4/2}]{sup -}Me{sup +} tetrahedral units are not sufficient to consume all of the alkali ions, and thus these alkali ions are easily leached from the glasses. All of the twelve Task 3 glass compositions were determined to be mainly amorphous, with some minor spinel phases. Several key structural units such as metasilicate chains and rings were identified, which confirms the current modeling

  19. Silicate-carbonate-salt liquid immiscibility and origin of the sodalite-haüyne rocks: study of melt inclusions in olivine foidite from Vulture volcano, S. Italy

    Science.gov (United States)

    Panina, Liya; Stoppa, Francesco

    2009-12-01

    Melt inclusions in clinopyroxenes of olivine foidite bombs from Serra di Constantinopoli pyroclastic flows of the Vulture volcano (Southern Italy) were studied in detail. The rocks contain abundant zoned phenocrysts and xenocrysts of clinopyroxene, scarce grains of olivine, leucite, haüyne, glass with microlites of plagioclase and K-feldspar. The composition of clinopyroxene in xenocrysts (Cpx I), cores (Cpx II), and in rims (Cpx III) of phenocrysts differs in the content of Mg, Fe, Ti, and Al. All clinopyroxenes contain two types of primary inclusion-pure silicate and of silicate-carbonate-salt composition. This fact suggests that the phenomena of silicate-carbonate immiscibility took place prior to crystallization of clinopyroxene. Homogenization of pure silicate inclusions proceeded at 1 225 - 1 190°C. The composition of conserved melts corresponded to that of olivine foidite in Cpx I, to tephrite-phonolite in Cpx II, and phonolite-nepheline trachyte in Cpx III. The amount of water in them was no more than 0.9 wt.%. Silicate-carbonate inclusions decrepitated on heating. Salt globules contained salts of alkali-sulphate, alkali-carbonate, and Ca-carbonate composition somewhat enriched in Ba and Sr. This composition is typical of carbonatite melts when decomposed into immiscible fractions. The formation of sodalite-haüyne rocks from Vulture is related to the presence of carbonate-salt melts in magma chamber. The melts conserved in clinopyroxenes were enriched in incompatible elements, especially in Cpx III. High ratios of La, Nb, and Ta in melts on crystallization of Cpx I and Cpx II suggest the influence of a carbonatite melt as carbonatites have extremely high La/Nb and Nb/Ta and this is confirmed by the appearance of carbonatite melts in magma chamber. Some anomalies in the concentrations and relatives values of Eu and especially Ga seems typical of Italian carbonatite related melts. The mantle source for initial melts was, most likely, rather uniform

  20. Trace element studies of silicate-rich inclusions in the Guin (UNGR) and Kodaikanal (IIE) iron meteorites

    Science.gov (United States)

    Kurat, Gero; Zinner, Ernst; Varela, Maria Eugenia

    2007-08-01

    A devitrified glass inclusion from the Guin (UNGR) iron consists of cryptocrystalline feldspars, pyroxenes, and silica and is rich in SiO2, Al2O3, and Na2O. It contains a rutile grain and is in contact with a large Cl apatite. The latter is very rich in rare earth elements (REEs) (˜80 × CI), which display a flat abundance pattern, except for Eu and Yb, which are underabundant. The devitrified glass is very poor in REEs (IIE) iron consists of glass only, whereas inclusion 2 consists of clinopyroxene, which is partly overgrown by low-Ca pyroxene, and apatite embedded in devitrified glass. All minerals are euhedral or have skeletal habits indicating crystallization from the liquid precursor of the glass. Pyroxenes and the apatite are rich in trace elements, indicating crystallization from a liquid that had 10-50 × CI abundances of REEs and refractory lithophile elements (RLEs). The co-existing glass is poor in REEs (˜0.1-1 × CI) and, consequently, a liquid of such chemical composition cannot have crystallized the phenocrysts. Glasses have variable chemical compositions but are rich in SiO2, Al2O3, Na2O, and K2O as well as in HFSEs, Be, B, and Rb. The REE abundance patterns are mostly flat, except for the glass-only inclusion, which has heavy rare earth elements (HREEs) > light rare earth elements (LREEs) and deficits in Eu and Yb—an ultrarefractory pattern. The genetic models suggested so far cannot explain what is observed and, consequently, we offer a new model for silicate inclusion formation in IIE and related irons. Nebular processes and a relationship with E meteorites (Guin) or Ca-Al-rich inclusions (CAIs) (Kodaikanal) are indicated. A sequence of condensation (CaS, TiN or refractory pyroxene-rich liquids) and vapor-solid elemental exchange can be identified that took place beginning under reducing and ending at oxidizing conditions (phosphate, rutile formation, alkali and Fe2+ metasomatism, metasomatic loss of REEs from glass).

  1. An Evaluation of Ethyl Silicate-Based Grouts for Weathered Silicate Stones

    Science.gov (United States)

    Dolph, Brittany Helen

    Culturally significant monuments made of weathered siliceous stone often display sub-surface condition issues such as cracks and voids. These issues require grouts that are ideally compatible with the composition and properties of the substrate. Based on the successful application of ethyl silicates as consolidants in recent literature, this study examines possible formulation pathways for the development of a grout incorporating ethyl silicate. Tetraethylorthosilicate (TEOS), dibutyltin dilaurate (DBTL) as a catalyst, silicone oil (PDMS), various grades of ground quartz, sepiolite, and hollow glass spheres were used in differing concentrations to create samples. These were visually and physically assessed on workability, separation, shrinkage, cracking, strength, and flexibility. Quantitative analysis was performed on selected formulations using UV-Vis-NIR reflectance spectroscopy in coordination with a weight loss experiment to investigate kinetics, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Successful formulations tended to include oligomeric TEOS, crushed quartz of mixed grades, sepiolite powder, and PDMS, and show promise for future investigations.

  2. Polymeric, Metallic, and Other Glasses in Introductory Chemistry

    Science.gov (United States)

    Hawkes, Stephen J.

    2008-01-01

    Non-ceramic glasses are not adequately discussed in introductory chemistry. Such glasses include polycarbonate, which many corrective lenses are made of, amber, enamel, gelatin, hard candy, coal, refrigerated glycerol, and metallic glasses that have been marketed in recent decades. What is usually discussed in elementary texts is siliceous glass,…

  3. Characterizing Amorphous Silicates in Extraterrestrial Materials

    Science.gov (United States)

    Fu, X.; Wang, A.; Krawczynski, M. J.

    2015-12-01

    Amorphous silicates are common in extraterrestrial materials. They are seen in the matrix of carbonaceous chondrites as well as in planetary materials. Tagish Lake is one of the most primitive carbonaceous meteorites in which TEM and XRD analyses found evidence for poorly crystalline phyllosilicate-like species; Raman spectra revealed amorphous silicates with variable degree of polymerization and low crystallinity. On Mars, CheMin discovered amorphous phases in all analyzed samples, and poorly crystalline smectite in mudstone samples. These discoveries pose questions on the crystallinity of phyllosilicates found by remote sensing on Mars, which is directly relevant to aqueous alteration during geologic history of Mars. Our goal is to use spectroscopy to better characterize amorphous silicates. We use three approaches: (1) using silicate glasses synthesized with controlled chemistry to study the effects of silicate polymerization and (2) using phyllosilicates synthesized with controlled hydrothermal treatment to study the effect of crystallinity on vibrational spectroscopy, finally (3) to use the developed correlations in above two steps to study amorphous phases in meteorites, and those found in future missions to Mars. In the 1st step, silicate glasses were synthesized from pure oxides in a range of NBO/T ratios (from 0 to 4). Depending on the targeted NBO/T and composition of mixed oxides, temperatures for each experiment fell in a range from 1260 to 1520 °C, run for ~ 4 hrs. The melt was quenched in liquid N2 or water. Homogeneity of glass was checked under optical microscopy. Raman spectra were taken over 100 spots on small chips free of bubbles and crystals. We have observed that accompanying an increase of NBO/T, there is a strengthening and a position shift of the Raman peak near 1000 cm-1 (Si-Onon-bridging stretching mode), and the weakening of broad Raman peaks near 500 cm-1 (ring breathing mode) and 700cm-1 (Si-Obridging-Si mode). We are building the

  4. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    OpenAIRE

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable or superior engineering properties to Portland cement. Moreover, this material shows great potential for sustainable development since its production has a significantly lower CO2 emission than the...

  5. RECYCLING PHOSPHORUS SLAG AS A PRECURSOR FOR ALKALI-ACTIVATED BINDER; IMPACT OF TYPE AND DOSAGE OF ACTIVATOR

    OpenAIRE

    Hojjatollah Maghsoodloorad; Hamidreza Khalili Amiri; Allahverdi Ali; Lachemi Mohamed; Hossain Khandaker M. Anwar

    2014-01-01

    The objectives of this study were to investigate the suitability of phosphorus slag as a precursor for alkali-activated binder by studying the effects of type and dosage of alkaline activators on compressive strength and efflorescence formation of the material. Different alkaline activators including; potassium hydroxide, sodium hydroxide, sodium carbonate, calcium hydroxide, and their combinations with liquid sodium silicate were used. Different levels of total alkali content (1, 3,...

  6. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill − Part 1

    Directory of Open Access Journals (Sweden)

    M. Kermani

    2015-06-01

    Full Text Available In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investigated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF. The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The mechanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength and physical (water retention properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  7. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill L Part 1

    Institute of Scientific and Technical Information of China (English)

    M. Kermani; F.P. Hassani; E. Aflaki; M. Benzaazoua; M. Nokken

    2015-01-01

    In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investi-gated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF). The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The me-chanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength) and physical (water retention) properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP) revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  8. Investigation on Structures and Properties of Yb3+-Doped Laser Glasses

    Institute of Scientific and Technical Information of China (English)

    Liu Shujiang; Lu Anxian; Tang Xiaodong; He Shaobo

    2006-01-01

    The Yb3+-doped silicate, phosphate and borophosphate laser glasses were prepared by means of conventional melt quenching technology.The physical and spectral properties of the glasses were investigated.The results show that, due to the existence of OH-, the fluorescence lifetime of phosphate glass is shorter than that of silicate glass, so silicate glass has better spectral properties than phosphate glass.Silicate glass has better mechanical and thermal properties than phosphate glass, but with the addition of B2O3, mechanical and thermal properties of phosphate glass are improved greatly without fluorescence quenching effect.This kind of borophosphate glass can be used in high average power solid state lasers.

  9. Mecanismes d'action des fines et des granulats de verre sur la reaction alcali-silice et la reaction pouzzolanique

    Science.gov (United States)

    Idir, Rachida

    Recycling composite glass with different colours in order to be manufactured into new glass products is at present not economically viable. Therefore, the search for new issues other than stockpile areas or dumping sites could be a serious opportunity. To a certain extent, one of the possible solutions is to use the recycled glass in manufacturing cements and in the preparation of concrete mixtures. However, it is essential to manage the two main behaviours that the glass can have when used in cement-based materials: (1) the use of glass as coarse aggregates reveals harmful behaviour related to alkali-silica reaction; (2) on the other hand, it can result in useful behaviour related to pozzolanic reaction if used as fine particles. Furthermore, the significant alkali content should not be overlooked as their mass corresponds to about 13% of the total mass of the glass and as they may activate the alkali-silica reaction. An experimental programme was conducted to provide answers to the various questions raised about the use of glass in cement-based materials. The first part of this work was primarily devoted to the evaluation of the reactive potential of glass in mortars (alkali and pozzolanic reactions). At this stage, nine classes of glass particles ranging from 3mum to 2.5 mm were considered. Then, fine glass particles were used in order to counteract the negative effect of some classes of coarse aggregates having revealed alkali-reactive behaviour. The second part of this work was performed to study the mechanisms that could explain the behaviours of fine and coarse particles in aqueous and concentrated environments. Different answers have been proposed to explain the observed behaviour in terms of grain sizes of glass. Keywords: Glass, Powder, Pozzolan, aggregates, alkali-reaction, alkali-aggregate reaction, alkali-silica reaction, Pouzzolanicity, alkalis, Mortars

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

    Science.gov (United States)

    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. INFLUENCE OF GLASS CULLET IN CEMENT PASTES

    Institute of Scientific and Technical Information of China (English)

    A.Karamberi; E.Chaniotakis; D.Papageorgiou; A.Moutsatsou

    2006-01-01

    The present study investigates glass and cement compatibility with a view to use glass as a cement replacement. Amber, flint and green glasses were chosen due to their prevalence in the Greek market as packaging materials. The factors under investigation were the pozzolanicity of the glass cullet, the hydration rate and the mechanical strength development of the cement pastes, as well as the expansion of the specimens due to alkali-silica reaction.Moreover, the potential enhancement of glass pozzolanic activity was examined. The results of the study were encouraging to show the potentiality of utilising glass cullet in cementitious products.

  12. Lessons from a “Failed” Experiment: Zinc Silicates with Complex Morphology by Reaction of Zinc Acetate, the Ionic Liquid Precursor (ILP Tetrabutylammonium Hydroxide (TBAH, and Glass

    Directory of Open Access Journals (Sweden)

    Andreas Taubert

    2008-08-01

    Full Text Available At elevated temperatures, the ionic liquid precursor (ILP tetrabutylammonium hydroxide reacts with zinc acetate and the glass wall of the reaction vessel. While the reaction of OH- with the glass wall is not surprising as such and could be considered a failed experiment, the resulting materials are interesting for a variety of applications. If done on purpose and under controlled conditions, the reaction with the glass wall results in uniform, well-defined hemimorphite Zn4Si2O7(OH2·nH2O and willemite Zn2SiO4 microcrystals and films. Their morphology can be adjusted by variation of the reaction time and reaction temperature. The hemimorphite can be transformed to Zn2SiO4 via calcination. The process is therefore a viable approach for the fabrication of porous films on glass surfaces with potential applications as catalyst support, among others.

  13. Determination of boron in silicates after ion exchange separation

    Science.gov (United States)

    Kramer, H.

    1955-01-01

    Existing methods for the determination of boron in silicates are not entirely satisfactory. Separation as the methyl ester is lengthy and frequently erratic. An accurate and rapid method applicable to glass, mineral, ore, and water samples uses ion exchange to remove interfering cations, and boron is determined titrimetrically in the presence of mannitol, using a pH meter to indicate the end point.

  14. Silicic Large Igneous Provinces

    Institute of Scientific and Technical Information of China (English)

    Scott Bryan

    2007-01-01

    @@ Large Igneous Provinces (LIPs) are the end-product of huge additions of magma to the continental crust both at the surface and at depth. Since the first categorisation of LIPs by Coffin & Eldholm (1994), it has been recognised that LIPs are more varied inform, age and character, and this includes the recognition of Silicic LIPs. Silicic LIPs are the largest accumulations of primary volcaniclastic rocks at the Earth's surface with areal extents >0.1 Mkm2 and extrusive and subvolcanic intrusive volumes >0.25 Mkm3. The Late Palaeozoic to Cenozoic Silicic LIP events are the best recognised and are similar in terms of their dimension, crustal setting, volcanic architecture and geochemistry.

  15. Alkali Aggregate Reaction in Alkali Slag Cement Mortars

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of "Mortar Bar Method",the ratio of cement to aggregate was kept as a constant 1∶2.25,the water-cement ratio of the mixture was 0.40,and six prism specimens were prepared for each batch of mixing proportions with dimensions of 10×10×60mm3 at 38±2℃ and RH≥95%, the influences of content and particle size of active aggregate, sort and content of alkali component and type of slag on the expansion ratios of alkali-activated slag cement(ASC) mortars due to alkali aggregate reaction(AAR) were studied. According to atomic absorption spectrometry,the amount of free alkali was measured in ASC mortars at 90d.The results show above factors affect AAR remarkably,but no dangerous AAR will occur in ASC system when the amount of active aggregate is below 15% and the mass fraction of alkali is not more than 5% (Na2O).Alkali participated in reaction as an independent component, and some hydrates containing alkali cations were produced, free alkalis in ASC system can be reduced enormously.Moreover,slag is an effective inhibitor, the possibility of generating dangerous AAR in ASC system is much lower at same conditions than that in ordinary Portland cement system.

  16. Summary Report: Glass-Ceramic Waste Forms for Combined Fission Products

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Riley, Brian J.; Turo, Laura A.; Tang, Ming; Kossoy, Anna

    2011-09-23

    Glass-ceramic waste form development began in FY 2010 examining two combined waste stream options: (1) alkaline earth (CS) + lanthanide (Ln), and (2) + transition metal (TM) fission-product waste streams generated by the uranium extraction (UREX+) separations process. Glass-ceramics were successfully developed for both options however; Option 2 was selected over Option 1, at the conclusion of 2010, because Option 2 immobilized all three waste streams with only a minimal decrease in waste loading. During the first year, a series of three glass (Option 2) were fabricated that varied waste loading-WL (42, 45, and 50 mass%) at fixed molar ratios of CaO/MoO{sub 3} and B{sub 2}O{sub 3}/alkali both at 1.75. These glass-ceramics were slow cooled and characterized in terms of phase assemblage and preliminary irradiation stability. This fiscal year, further characterization was performed on the FY 2010 Option 2 glass-ceramics in terms of: static leach testing, phase analysis by transmission electron microscopy (TEM), and irradiation stability (electron and ion). Also, a new series of glass-ceramics were developed for Option 2 that varied the additives: Al{sub 2}O{sub 3} (0-6 mass%), molar ratio of CaO/MoO{sub 3} and B{sub 2}O{sub 3}/alkali (1.75 to 2.25) and waste loading (50, 55, and 60 mass%). Lastly, phase pure powellite and oxyapatite were synthesized for irradiation studies. Results of this fiscal year studies showed compositional flexibility, chemical stability, and radiation stability in the current glass-ceramic system. First, the phase assemblages and microstructure of all of the FY 2010 and 2011 glass-ceramics are very similar once subjected to the slow cool heat treatment. The phases identified in these glass-ceramics were oxyapatite, powellite, cerianite, and ln-borosilicate. This shows that variations in waste loading or additives can be accommodated without drastically changing the phase assemblage of the waste form, thus making the processing and performance

  17. Low-temperature heat capacity of diopside glass (CaMgSi2O6): A calorimetric test of the configurational-entropy theory applied to the viscosity of liquid silicates

    Science.gov (United States)

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

    1986-01-01

    Heat-capacity measurements have been made between 8 and 370 K on an annealed and a rapidly quenched diopside glass. Between 15 and 200 K, Cp does not depend significantly on the thermal history of the glass. Below 15 K Cp is larger for the quenched than for the annealed specimen. The opposite is true above 200 K as a result of what is interpreted as a secondary relaxation around room temperature. The magnitude of these effects, however, is small enough that the relative entropies S(298)-S(0) of the glasses differ by only 0.5 J/mol K, i.e., a figure within the combined experimental uncertainties. The insensitivity of relative entropies to thermal history supports the assumption that the configurational heat capacity of the liquid may be taken as the heat capacity difference between the liquid and the glass (??Cp). Furthermore, this insensitivity allows calculation of the residual entropies at 0 K of diopside glasses as a function of the fictive temperature from the entropy of fusion of diopside and the heat capacities of the crystalline, glassy and liquid phases. For a glass with a fictive temperature of 1005 K, for example, this calorimetric residual entropy is 24.3 ?? 3 J/mol K, in agreement with the prediction made by RICHET (1984) from an analysis of the viscosity data with the configurational-entropy theory of relaxation processes of Adam and Gibbs (1965). In turn, all the viscosity measurements for liquid diopside, which span the range 0.5-4?? 1013 poise, can be quantitatively reproduced through this theory with the calorimetrically determined entropies and ??Cp data. Finally, the unclear significance of "activation energies" for structural interpretations of viscosity data is emphasized, and the importance of ??Cp and glass-transition temperature systematics for determining the composition and temperature dependences of the viscosity is pointed out. ?? 1986.

  18. Natural Alkali Shifts to the Methanol Business

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Inner Mongolia Yuanxing Natural Alkali Co., Ltd. (Natural Alkali SZ: 000683) established in 1997 is a large chemical enterprise with new energy as its leading business and natural gas chemicals and natural alkali chemicals as the supplement business.

  19. Redox kinetics and mechanism in silicate melts

    International Nuclear Information System (INIS)

    This work contributes to better understand iron redox reactions and mechanisms in silicate melts. It was conducted on compositions in both Na2O-B2O3-SiO2-FeO and Na2O-Al2O3-SiO2-FeO systems. The influence of boron-sodium and aluminum-sodium substitutions and iron content on properties and structure of glasses and on the iron redox kinetics has been studied by Raman, Moessbauer and XANES spectroscopies at the B and Fe K-edges. In borosilicate glasses, an increase in iron content or in the Fe3+/ΣFe redox state implies a structural rearrangement of the BO4 species in the glass network whereas the BO3 and BO4 relative proportions remain nearly constant. In all studied glasses and melts, Fe3+ is a network former in tetrahedral coordination, unless for aluminosilicates of ratio Al/Na≥1 where Fe3+ is a network modifier in five-fold coordination. Near Tg, diffusion of network modifying cations controls the iron redox kinetics along with a flux of electron holes. At liquidus temperatures, oxygen diffusion is considered to be the mechanism that governs redox reactions. This study shows the role played by the silicate network polymerization on the redox kinetics. In borosilicate melts, iron redox kinetics depends on the boron speciation between BO3 and BO4 that depends itself on the sodium content. Furthermore, an increase in the network-former/network-modifier ratio implies a decrease in oxygen diffusion that results in a slowing down of the redox kinetics. The obtained results allow a description of the iron redox kinetics for more complex compositions as natural lavas or nuclear waste model glasses. (author)

  20. Topological Principles of Borosilicate Glass Chemistry - An Invited Talk

    DEFF Research Database (Denmark)

    Mauro, J.C.; Smedskjær, Morten Mattrup; Youngman, R. E.;

    topological representation of alkali-alkaline earth-borosilicate glasses that enables the accurate prediction of properties such as glass transition temperature, liquid fragility, hardness, and configurational heat capacity. The implications of the glass topology are discussed in terms of both the temperature...

  1. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Lee, Martin R.; Chatzitheodoridis, Elias

    2016-07-01

    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.

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

    Science.gov (United States)

    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.

  4. Sodium diffusion in boroaluminosilicate glasses

    DEFF Research Database (Denmark)

    Smedskjaer, Morten M.; Zheng, Qiuju; Mauro, John C.;

    2011-01-01

    Understanding the fundamentals of alkali diffusion in boroaluminosilicate (BAS) glasses is of critical importance for advanced glass applications, e.g., the production of chemically strengthened glass covers for personal electronic devices. Here, we investigate the composition dependence of isoth......Understanding the fundamentals of alkali diffusion in boroaluminosilicate (BAS) glasses is of critical importance for advanced glass applications, e.g., the production of chemically strengthened glass covers for personal electronic devices. Here, we investigate the composition dependence...... of isothermal sodium diffusion in BAS glasses by ion exchange, inward diffusion, and tracer diffusion experiments. By varying the [SiO2]/[Al2O3] ratio of the glasses, different structural regimes of sodium behavior are accessed. We show that the mobility of the sodium ions decreases with increasing [SiO2]/[Al2O...... diffusivity are explored in terms of the structural role of ferric and ferrous ions. By comparing the results obtained by the three approaches, we observe that both the tracer Na diffusion and the Na-K interdiffusion are significantly faster than the Na inward diffusion. The origin of this discrepancy could...

  5. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

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

  6. Analysis of polycyclic aromatic hydrocarbons I. Determination by gas chromatography with glass and fused silica capillary columns; Analisis de Hidrocarburos aromaticos policiclicos. I. Determinacion por cromatografia de gases con columnas capilares de vidrio de silice fundida

    Energy Technology Data Exchange (ETDEWEB)

    Perez, M. M.; Gonzalez, D.

    1987-07-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (Author) 17 refs.

  7. An extended topological model for binary phosphate glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian; Rodrigues, B.P.; Wondraczek, L.;

    2014-01-01

    , but for larger ions a significant fraction is broken. By accounting for the fraction of intact modifying ion related constraints, qγ, the Tg(x) of alkali phosphate glasses is predicted. By examining alkali, alkaline earth and rare earth metaphosphate glasses we find that the effective number of intact...... constraints per modifying cation is linearly related to the charge-to-distance ratio of the modifying cation to oxygen....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-13

    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.

  9. Silicates in Alien Asteroids

    Science.gov (United States)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  10. Discovery of ancient silicate stardust in a meteorite.

    Science.gov (United States)

    Nguyen, Ann N; Zinner, Ernst

    2004-03-01

    We have discovered nine presolar silicate grains from the carbonaceous chondrite Acfer 094. Their anomalous oxygen isotopic compositions indicate formation in the atmospheres of evolved stars. Two grains are identified as pyroxene, two as olivine, one as a glass with embedded metal and sulfides (GEMS), and one as an Al-rich silicate. One grain is enriched in 26Mg, which is attributed to the radioactive decay of 26Al and provides information about mixing processes in the parent star. This discovery opens new means for studying stellar processes and conditions in various solar system environments.

  11. Moessbauer spectroscopic study of the thermal neutron irradiated potassium borate glasses

    International Nuclear Information System (INIS)

    Moessbauer study was performed for thermal neutron irradiated potassium borate glasses containing 7 mol % of ferric oxide. The alkali contents of the glasses were changed from 10 to 40 mol %. The decrease of isomer shift was observed by the irradiation of the glasses when the alkali content was higher than 20 mol %. The increase of the quadrupole splitting was also observed in the low alkali content region. These results were discussed in connection with the nuclear reaction of 10B(n,α)7Li and the network structure of the borate glasses. (author)

  12. Formation of apatite on the surface of plasma sprayed dicalcium silicate coating

    Institute of Scientific and Technical Information of China (English)

    LIU Xuan-yong; DING Chuan-xian

    2001-01-01

    @@ INTRODUCTION Since the discovery of Bioglass by Hench et al. in 1969, various kinds of glass and glass-ceramic have been found to bond to living bone. All those bioglass and glass-ceramic including CaO-SiO2 components contributed to the bioactivity of those materials. The polymorphism of dicalcium silicate (Ca2SiO4) has been well studied because of the considerable importance of this compound in the cement and refractories industries. Dicalcium silicate may be bioactive in human body because it is also composed of CaO-SiO2 components.

  13. Detection of structural heterogeneity of glass melts

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2004-01-01

    The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One is the hyp......The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One...... is discussed. The ordered structure of glass melts above the liquidus temperature is indirectly characterized by use of X-ray diffraction method. The new approaches are of importance for monitoring the glass melting and forming process and for improving the physical properties of glasses and glass fibers....

  14. Studies and testing of antireflective (AR) coatings for soda-lime glass

    Science.gov (United States)

    Pastirik, E. M.; Sparks, T. G.; Coleman, M. G.

    1978-01-01

    Processes for producing antireflection films on glass are concentrated in three areas: acid etching of glass, plasma etching of glass, and acid development of sodium silicate films on glass. The best transmission was achieved through the acid etching technique, while the most durable films were produced from development of sodium silicate films. Control of the acid etching technique is presently inadequate for production implementation. While films having excellent antireflective properties were fabricated by plasma etching techniques, all were water soluble.

  15. Heat Capacity of Hydrous Silicate Melts

    Science.gov (United States)

    Robert, G.; Whittington, A. G.; Stechern, A.; Behrens, H.

    2015-12-01

    We determined the heat capacities of four series of glasses and liquids of basaltic and basaltic andesite compositions including two natural remelts from Fuego volcano, Guatemala, and two Fe-free analogs. The samples are low-alkali, Ca- and Mg-rich aluminosilicates with non-bridging oxygen to tetrahedrally-coordinated cation ratios (NBO/T) ranging between 0.33 and 0.67. Differential scanning calorimetry measurements were performed at atmospheric pressure between room temperature and ≈100 K above the glass transition for hydrous samples and up to ≈1800 K for dry samples. The water contents investigated range up to 5.34 wt.% (16.4 mol%). Water does not measurably affect the heat capacity of glasses (T glass transition, there is a ≈30-40% change in heat capacity, which generally gets larger with increasing water content and with decreasing polymerization. The onset of the glass transition in hydrous samples also occurs below the Dulong-Petit limit of 3R/g atom. We see little change in liquid heat capacity with increasing water content; hydrous liquid heat capacities are within 3-6% of the dry liquid, at low temperatures just above the glass transition. However, dry liquids show a decrease in heat capacity with increasing temperature above the glass transition, from supercooled to superliquidus temperatures. Liquid heat capacity values just above the glass transition range between 95-100 J/mol K, whereas liquid heat capacity values at superliquidus temperatures are between 85-91 J/mol K. Comparison with other studies of the heat capacity of hydrous glasses and liquids shows that the liquid heat capacity of strongly depolymerized samples (NBO/T ≥ 0.8) increases with increasing water content, whereas depolymerized samples (0.4 ≤ NBO/T ≤ 0.8) or polymerized samples (NBO/T ≤ 0.4) generally show little change or a moderate decrease in liquid heat capacity with increasing water content.

  16. Upgrading platform using alkali metals

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

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

  17. The Effect of Sm2O3 on the Chemical Stability of Borosilicate Glass and Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yongqiang; WANG Mitang; LI Mei; WANG Ming; LIU Quansheng

    2014-01-01

    Sm2O3 containing zinc-borosilicate glass and glass ceramics were prepared by melt quenching method, and the effect of Sm2O3 and micro-crystallization on the chemical stability of borosilicate glass was explored. DTA analysis showed that the endothermic peak and exothermic peak of basic glass changed from 635℃and 834℃to 630℃and 828℃respectively as a result of the doping of Sm2O3. XRD analysis showed the promoting effect of Sm2O3 on crystallization ability of this glass. The cumulative mass loss of base glass, Sm2O3 containing glass, glass ceramic and Sm2O3 containing glass ceramic was 0.289, 0.253, 0.329, 0.269 mg/mm2 respectively after 26 days corrosion in alkali solution, and 1.293, 1.290, 0.999, 1.040 mg/mm2 respectively in acidic erosion medium. Micro-crystallization decreased and improved the alkali and acid resistance of borosilicate glass respectively, the addition of Sm2O3 increased the alkali resistance of base glass and glass ceramics, and the slight effect of Sm2O3 on the acid resistance of borosilicate glass was also observed.

  18. Quantitative Evaluation by Glucose Diffusion of Microleakage in Aged Calcium Silicate-Based Open-Sandwich Restorations

    OpenAIRE

    Camps, J.; Tassery, H.; Koubi, G.; Elmerini, H.; Koubi, S.

    2012-01-01

    This study compared the in vitro marginal integrity of open-sandwich restorations based on aged calcium silicate cement versus resin-modified glass ionomer cement. Class II cavities were prepared on 30 extracted human third molars. These teeth were randomly assigned to two groups ( = 1 0 ) to compare a new hydraulic calcium silicate cement designed for restorative dentistry (Biodentine, Septodont, Saint Maur des Fossés, France) with a resin-modified glass ionomer cement (Ionolux, Voco, Cuxh...

  19. Structural and crystallisation study of a rare earth alumino borosilicate glass designed for nuclear waste confinement; Etude de la structure et du comportement en cristallisation d'un verre nucleaire d'aluminoborosilicate de terre rare

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, A

    2007-09-15

    This work is devoted to the study of a rare earth alumino borosilicate glass, which molar composition is 61,81 SiO{sub 2} - 3,05 Al{sub 2}O{sub 3} - 8,94 B{sub 2}O{sub 3} - 14,41 Na{sub 2}O - 6,33 CaO - 1,90 ZrO{sub 2} - 3,56 Nd{sub 2}O{sub 3}, and envisaged for the immobilization of nuclear wastes originating from the reprocessing of high discharge burn up spent fuel. From a structural viewpoint, we investigated the role of the modifier cations on the arrangement of the glass network through different modifications of the glass composition: variation of the Na/Ca ratio and modification of the nature of the alkali and alkaline earth cations. The NMR and Raman spectroscopic techniques were useful to determine the distribution of modifier cations among the glass network and also to cast light on the competition phenomena occurring between alkali and alkaline earth cations for charge compensation of [AlO{sub 4}]{sup -} and [BO{sub 4}]{sup -} species. The neodymium local environment could be probed by optical absorption and EXAFS spectroscopies which enabled to better understand the insertion mode of Nd{sup 3+} ions among the silicate domains of the glass network. Concerning the crystallization behavior we were interested in how the glass composition may influence the crystallization processes and especially the formation of the apatite phase of composition Ca{sub 2}Nd{sub 8}(SiO{sub 4}){sub 6}O{sub 2}. In particular, this work underlined the important role of both alkaline earth and rare earth cations on the crystallization of the apatite phase. (author)

  20. Behaviour of Silicate Melts in Respect of Volume

    Institute of Scientific and Technical Information of China (English)

    张金民; 叶大年

    1989-01-01

    The volumes per oxygen of some silicate melts have been calculated and then compared with those of silicate glasses.It is suggested that the volume of a silicate melt can be divided into two parts.One is contri buted by the silicon-oxygen network and the other by the “oxides”.Variation patterns of VPOs suggest that the volume of the Si-O network generally remains unchanged and the expansion of the melt is caused mainly by the locat expansion of the “oxides”.It is further proposed that the radius of O2- shows little variation,in striking contrast to the radius of cations.The mechanism governing the expansion is discussed in detail.

  1. K8(K5F)U6Si8O40: An Intergrowth Uranyl Silicate.

    Science.gov (United States)

    Morrison, Gregory; Tran, T Thao; Halasyamani, P Shiv; Zur Loye, Hans-Conrad

    2016-04-01

    Single crystals of K8(K5F)U6Si8O40 were grown from a mixed alkali halide flux. K8(K5F)U6Si8O40 is the first intergrowth uranyl silicate, being composed of alternating slabs related to two previously reported uranyl silicates: Cs2USiO6 and [Na9F2][(UO2)(UO2)2(Si2O7)2]. It exhibits intense luminescence, which is influenced by the [(UO2)2O] dimers present in the structure. PMID:26974872

  2. Flexural, Impact Properties and Sem Analysis of Bamboo and Glass Fiber Reinforced Polyester Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Raghavendra Rao. H

    2014-08-01

    Full Text Available The Flexural, Impact properties and Scanning electron microscope analysis of Bamboo/glass fibers Reinforced polyester Hybrid composites were studied. The effect of alkali treatment of the bamboo fibers on these properties was also studied. It was observed that the Flexural, impact properties of the hybrid composite increase with glass fiber content. These properties found to be higher when alkali treated bamboo fibers were used in the hybrid composites. The elimination of amorphous hemi-cellulose with alkali treated leading to higher crystallinity of the bamboo fibers with alkali treatment may be responsible for these observations. The author investigated the interfacial bonding between Glass/Bamboo reinforced polyester composites. The effect of alkali treatment on the bonding between Glass/Bamboo composites was also studied.

  3. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  4. Nitrogen distribution between aqueous fluids and silicate melts

    Science.gov (United States)

    Li, Yuan; Huang, Ruifang; Wiedenbeck, Michael; Keppler, Hans

    2015-02-01

    The partitioning of nitrogen between hydrous fluids and haplogranitic, basaltic, or albitic melts was studied at 1-15 kbar, 800-1200 °C, and oxygen fugacities (fO2) ranging from the Fe-FeO buffer to 3log units above the Ni-NiO buffer. The nitrogen contents in quenched glasses were analyzed either by electron microprobe or by secondary ion mass spectrometry (SIMS), whereas the nitrogen contents in fluids were determined by mass balance. The results show that the nitrogen content in silicate melt increases with increasing nitrogen content in the coexisting fluid at given temperature, pressure, and fO2. Raman spectra of the silicate glasses suggest that nitrogen species change from molecular N2 in oxidized silicate melt to molecular ammonia (NH3) or the ammonium ion (NH4+) in reduced silicate melt, and the normalized Raman band intensities of the nitrogen species linearly correlate with the measured nitrogen content in silicate melt. Elevated nitrogen contents in silicate melts are observed at reduced conditions and are attributed to the dissolution of NH3/NH4+. Measured fluid/melt partition coefficients for nitrogen (DNfluid/ melt) range from 60 for reduced haplogranitic melts to about 10 000 for oxidized basaltic melts, with fO2 and to a lesser extent melt composition being the most important parameters controlling the partitioning of nitrogen. Pressure appears to have only a minor effect on DNfluid/ melt in the range of conditions studied. Our data imply that degassing of nitrogen from both mid-ocean ridge basalts and arc magmas is very efficient, and predicted nitrogen abundances in volcanic gases match well with observations. Our data also confirm that nitrogen degassing at present magma production rates is insufficient to accumulate the atmosphere. Most of the nitrogen in the atmosphere must have degassed very early in Earth's history and degassing was probably enhanced by the oxidation of the mantle.

  5. Sol-Gel Synthesis and Luminescent Characteristic of Doped Eu3+ Silicate-Silica Phosphor

    Institute of Scientific and Technical Information of China (English)

    Yang Liangzhun; Yu Xibin; Yang Shiping; Zhou Pingle; Tang Jinfeng; Peng Xiudong

    2005-01-01

    Eu-doped silicate complex gel nano-particles was obtained by sol-gel process and characterized with TEM, XRD, PL, etc. The well dispersed particles have particle size about 60~70 nm with specific surface area 98.3 m2·g-1. The complex gel phosphor gives a broad and strong luminescent emission originating from Eu2+ ions centered at 425 nm. The emission band shifts to shorter wavelengths with the increase of the ion radius of the alkali earth metals, but the band becomes red-shifted gradually with the increase of the ion radius of the alkali metals(except Li+). These divalent Eu2+ ions originate in inequivalent substitution of the alkaline earth ions. The presence of alkaline ions is favorable for the increasing emission intensity of the Eu2+ and lowering crystalline temperature of the silicate complex gel.

  6. Dentin-cement Interfacial Interaction: Calcium Silicates and Polyalkenoates

    OpenAIRE

    Atmeh, A.R.; Chong, E. Z.; Richard, G; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline c...

  7. Viscous Glass Sealants for SOFC Applications

    Energy Technology Data Exchange (ETDEWEB)

    Scott Misture

    2012-09-30

    Two series of silicate glasses that contain gallium as the primary critical component have been identified and optimized for viscous sealing of solid oxide fuel cells operating from 650 to 850°C. Both series of glass sealants crystallize partially upon heat treatment and yield multiphase microstructures that allow viscous flow at temperatures as low as 650°C. A fully amorphous sealant was also developed by isolating, synthesizing and testing a silicate glass of the same composition as the remnant glassy phase in one of the two glass series. Of ~40 glasses tested for longer than 500 hours, a set of 5 glasses has been further tested for up to 1000h in air, wet hydrogen, and against both yttria-stabilized zirconia and aluminized stainless steel. In some cases the testing times reached 2000h. The reactivity testing has provided new insight into the effects of Y, Zr, and Al on bulk and surface crystallization in boro-gallio-silicate glasses, and demonstrated that at least 5 of the newly-developed glasses are viable viscous sealants.

  8. Epitaxial Growth of a Methoxy-Functionalized Quaterphenylene on Alkali Halide Surfaces

    DEFF Research Database (Denmark)

    Balzer, Frank; Sun, Rong; Parisi, Jürgen;

    2015-01-01

    The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of lowenergy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X...

  9. Corrosion by the Alkali Metals

    International Nuclear Information System (INIS)

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

  10. A new scintillating glass for high energy physics applications

    International Nuclear Information System (INIS)

    A new scintillating glass has been developed containing Cerium (3+) oxide in an aluminate host glass. In this material the scintillation emission spectrum is red-shifted relative to that observed for Ce/sup 3+/ in silicate glasses. Additionally, emission and absorption spectra are more widely separated in the aluminate composition, suggesting that such glasses might have improved light transmission properties. The refractive index is high, making it a potentially interesting material for use in fiber-optic tracking detectors

  11. Alkali-silica reaction resistant concrete using pumice blended cement

    Science.gov (United States)

    Ramasamy, Uma

    Durability of structures is a major challenge for the building industry. One of the many types of concrete deterioration that can affect durability is alkali-silica reaction (ASR). ASR has been found in most types of concrete structures, including dams, bridges, pavements, and other structures that are 20 to 50 years old. The degradation mechanism of ASR produces a gel that significantly expands in the presence of water as supplied from the surrounding environment. This expansion gel product can create high stresses and cracking of the concrete, which can lead to other forms of degradation and expensive structural replacement costs. The four essential factors that produce an expansive ASR gel in concrete are the presence of alkalis, siliceous aggregate, moisture, and free calcium hydroxide (CH). If concrete is starved of any one of these essential components, the expansion can be prevented. Reducing CH through the use of a supplementary cementitious material (SCM) such as natural pozzolan pumice is the focus of this research. By using a pozzolan, the amount of CH is reduced with time based on the effectiveness of the pozzolan. Many pozzolans exist, but one such naturally occurring pozzolanic material is pumice. This research focuses on determining the effect of a finely ground pumice as a SCM in terms of its resistance to ASR expansion, as well as improving resistance to other potential concrete durability mechanisms. In spite of having high alkali contents in the pumice, mixtures containing the SCM pumice more effectively mitigated the ASR expansion reaction than other degradation mechanisms. Depending on the reactivity of the aggregates and fineness of the pumice, 10-15% replacement of cement with the pumice was found to reduce the ASR expansion to the acceptable limits. The amount of CH remaining in the concrete was compared to the ASR expansion in order to improve understanding of the role of CH in the ASR reaction. Thermo-gravimetric analysis (TGA) and X

  12. Distinctive microstructural features of aged sodium silicate-activated slag concretes

    Energy Technology Data Exchange (ETDEWEB)

    San Nicolas, Rackel [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Bernal, Susan A. [Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD (United Kingdom); School of Materials Engineering, Composite Materials Group, Universidad del Valle, Cali (Colombia); Mejía de Gutiérrez, Ruby [School of Materials Engineering, Composite Materials Group, Universidad del Valle, Cali (Colombia); Deventer, Jannie S.J. van [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012 (Australia); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD (United Kingdom)

    2014-11-15

    Electron microscopic characterisation of 7-year old alkali-activated blast-furnace slag concretes enabled the identification of distinct microstructural features, providing insight into the mechanisms by which these materials evolve over time. Backscattered electron images show the formation of Liesegang-type ring formations, suggesting that the reaction at advanced age is likely to follow an Oswald supersaturation–nucleation–depletion cycle. Segregation of Ca-rich veins, related to the formation of Ca(OH){sub 2}, is observed in microcracked regions due to the ongoing reaction between the pore solution and available calcium from remnant slag grains. A highly dense and uniform interfacial transition zone is identified between siliceous aggregate particles and the alkali activated slag binders, across the concretes assessed. Alkali-activated slag concretes retain a highly dense and stable microstructure at advanced ages, where any microcracks induced at early ages seem to be partially closing, and the remnant slag grains continue reacting.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  16. Construction of thermionic alkali-ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Ul Haq, F.

    1986-04-01

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

  17. Influence of addition of B2O3 on properties of Yb3+ -doped phosphate laser glass

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-jiang; LU An-xian; TANG Xiao-dong; HE Shao-bo

    2006-01-01

    The three host glasses doped with Yb3+ were prepared by means of conventional melt quenching technol ogy, and the influence on physical and spectral properties of phosphate glass due to addition of B2O3 was investigated and compared with silicate glass. The results show that due to the existence of OH- impurities which induce thenon-radiative route, the fluorescence lifetime of phosphate glass is shorter, so silicate glass has better spectral properties than phosphate glass. Silicate glass has more excellent thermal-mechanical properties than phosphate glass,but with the addition of B2O3, thermal-mechanical properties of phosphate glass are improved greatly without fluo rescence quenching effect, and this kind of borophosphate glass will be the candidate to be used in high average pow er solid state laser.

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

    Science.gov (United States)

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

    2011-12-13

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Alkali-activated blast furnace slag-zeolite cements and concretes

    International Nuclear Information System (INIS)

    The aim of this work has been the study of alkali-activated slag-zeolite cements and concretes based on them. Various compositions have been tested and some characteristics such as the compressive strength have been measured versus zeolite additions. A table lists the specific surface area and particle size distributions of different cements. The conclusions of the study are the following. First, alkali-activated slag cements and concretes based on them are effective for immobilization of radioactive wastes and the production of building structures, designed for high radiation load. Secondly, zeolite-containing mineral additions are able to increase the immobilization capacity and radiation resistance of alkali-activated blast furnace slag cements and concretes. Thirdly, the efficiency of different zeolite-containing additions - 10% to increase alkali-activated blast furnace slag-zeolite cement strength was established. It is with alkaline components of water-glass, sodium carbonate, sodium sulphate. Fourth, the effective way of introducing zeolite additions in alkali-activated blast furnace slag-zeolite cement is inter-grinding of the slag and addition. Increase in strength of alkali-activated blast furnace slag-zeolite cement stone is 40% higher than that of the stone of a mixture of separately milled components. Fifth, Alkali-activated blast furnace slag-zeolite cements with zeolite-containing additions with a compressive strength of 10.1 to 140 MPa; alkali-activated blast furnace slag-zeolite cements mortars with compressive strength from 35.2 to 97.7 MPa; alkali-activated blast furnace slag-zeolite cements concretes with compressive strength up to 84.5 MPa and frost resistant up to 800 cycles were obtained

  1. Alkali and transition metal phospholides

    International Nuclear Information System (INIS)

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

  2. Mineralogy and Ar-Ar Age of the Tarahumara IIE Iron, with Reference to the Origin of Alkali-Rich Materials

    Science.gov (United States)

    Takeda, Hiroshi; Bogard, Donald D.; Otsuki, Mayumi; Ishii, Teruaki

    2003-01-01

    Silicate inclusions in nine known IIE irons show diversity in mineralogy, and Colomera, Kodaikanal, Elga and Miles contain alkali-rich silicate inclusions. Bogard et al. showed evidence of a complex parent body evolution for IIE irons based on Ar-39-Ar-40 ages. Colomera contained a sanidine-rich surface inclusion and the K-enrichment trends in the Na-rich inclusions are different from those of other IIEs. To elucidate the origin of K-rich materials, we studied the mineralogy and Ar-Ar age of silicate inclusions from the Tarahumara IIE iron meteorite.

  3. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

    Science.gov (United States)

    Zhang, Na; Li, Hongxu; Zhao, Yazhao; Liu, Xiaoming

    2016-04-01

    Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities. PMID:26691955

  4. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

    Science.gov (United States)

    Zhang, Na; Li, Hongxu; Zhao, Yazhao; Liu, Xiaoming

    2016-04-01

    Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities.

  5. On the plastic deformation of soda-lime glass - a Cr3+ luminescence study of densification

    OpenAIRE

    Perriot, Antoine; Barthel, Etienne; Kermouche, Guillaume; Querel, Gilles; Vandembroucq, Damien

    2011-01-01

    Silicate glasses are known to experience an anomalous plastic behavior at micron-scale: 1) they exhibit densification when flowing plastically and 2) hydrostatic pressure affects the yield point. We have previously shown (A. Perriot et al. J. Am. Ceram. Soc. 89 (2006) 596) that densification maps are useful to infer a reliable constitutive law for the plastic response of silicate glasses. It is shown here that for soda-lime glass Cr3+ luminescence microspectroscopy may be used for that purpos...

  6. Chalcophile element partitioning into magmatic sulphides: the effect of silicate melt composition

    Science.gov (United States)

    Kiseeva, Kate; Wood, Bernard

    2016-04-01

    Partitioning of many elements between sulphide and silicate melts is a function of the FeO content of the silicate liquid (Kiseeva and Wood, 2013). The theoretical relationship is a linear one between LogDM (DM=[M]sulph/[M]sil) and -log[FeO] with a slope of n/2, where n is the valency of trace element M. In practice we find that the slope deviates from the theoretical one because of the presence of oxygen in the sulphide. In our recent study we investigated the effects of sulphide composition and temperature on chalcophile element partitioning between sulphide and silicate liquids (Kiseeva and Wood, 2015). We have concluded that partitioning of most chalcophile elements is a strong function of the oxygen (or FeO) content of the sulphide. As expected, lithophile elements partition more strongly into sulphide as its oxygen content increases, while chalcophile elements enter sulphide less readily with increasing oxygen. The effect of Ni and Cu content of sulphide is significantly smaller than the effect of oxygen, while the effects of temperature are large only for a number of elements (such as Ni, Cu, Ag). In this study we show that in addition to the effect of sulphide composition, for certain elements the effect of silicate melt composition on sulphide/silicate partitioning can be quite large. For instance, within the range of NBO/T between 0.5 and 2 the DTlsulph/sil changes in order of magnitude. For the elements, like Pb, partition coefficient does not seem to change much with the silicate melt composition, while for Sb the effect of the silicate melt composition on D is a factor of 3. Partitioning of chalcophile elements into more evolved, alkali-rich and felsic magmas is estimated to be very different from the partitioning into basaltic melts, mainly due to the strong effects of temperature and alkali components. Although it is highly likely that sulphide is in solid form at liquidus temperatures for dacite and rhyolite and thus the partitioning of chalcophile

  7. Phase separation in an ionomer glass

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Tian, K.V.; Dobó-Nagy, C.;

    2015-01-01

    The G338 ionomer glass is a fluoro-alumino-silicate system, which is used as the powder component of glass ionomer cements (GICs) in dental applications. However, despite progress in understanding the nature of this glass, chemical identity of its separated amorphous phases has not yet been...... conclusively determined. In this work, we identify these phases by performing differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses on both the as-received glass and heat-treated samples. We detected three glass transitions in the as-received G338 glass during DSC upscaning, implying...... amorphous phases in G388 are Ca/Na-Al-Si-O, Ca-Al-F and Ca-P-O-F phases, respectively. However, the exact chemical compositions of the three phases still require further exploration. The results of this work are important for understanding the impact of phase separation within ionomer glasses on the setting...

  8. Environmental silicate nano-biocomposites

    CERN Document Server

    Pollet, Eric

    2012-01-01

    Environmental Silicate Nano-Biocomposites focuses on nano-biocomposites, which are obtained by the association of silicates such as bioclays with biopolymers. By highlighting recent developments and findings, green and biodegradable nano-composites from both renewable and biodegradable polymers are explored. This includes coverage of potential markets such as packaging, agricultures, leisure and the fast food industry. The knowledge and experience of more than twenty international experts in diverse fields, from chemical and biochemical engineering to applications, is brought together in four different sections covering: Biodegradable polymers and Silicates, Clay/Polyesters Nano-biocomposites, Clay/Agropolymers Nano-biocomposites, and Applications and biodegradation of Nano-biocomposites. By exploring the relationships between the biopolymer structures, the processes, and the final properties Environmental Silicate Nano-Biocomposites explains how to design nano-materials to develop new, valuable, environmenta...

  9. Process for Converting Waste Glass Fiber into Value Added Products, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hemmings, Raymond T.

    2005-12-31

    Nature of the Event: Technology demonstration. The project successfully met all of its technical objectives. Albacem has signed an exclusive licensing agreement with Vitro Minerals Inc., a specialty minerals company, to commercialize the Albacem technology (website: www.vitrominerals.com). Location: The basic research for the project was conducted in Peoria, Illinois, and Atlanta, Georgia, with third-party laboratory verification carried out in Ontario, Canada. Pilot-scale trials (multi-ton) were conducted at a facility in South Carolina. Full-scale manufacturing facilities have been designed and are scheduled for construction by Vitro Minerals during 2006 at a location in the Georgia, North Carolina, and South Carolina tri-state area. The Technology: This technology consists of a process to eliminate solid wastes generated at glass fiber manufacturing facilities by converting them to value-added materials (VCAS Pozzolans) suitable for use in cement and concrete applications. This technology will help divert up to 250,000 tpy of discarded glass fiber manufacturing wastes into beneficial use applications in the concrete construction industry. This technology can also be used for processing glass fiber waste materials reclaimed from monofills at manufacturing facilities. The addition of take-back materials and reclamation from landfills can help supply over 500,000 tpy of glass fiber waste for processing into value added products. In the Albacem process, waste glass fiber is ground to a fine powder that effectively functions as a reactive pozzolanic admixture for use in portland ce¬ment-based building materials and products, such as concrete, mortars, terrazzo, tile, and grouts. Because the waste fiber from the glass manufacturing industry is vitreous, clean, and low in iron and alkalis, the resulting pozzolan is white in color and highly consistent in chemical composition. This white pozzolan, termed VCAS Pozzolan (for Vitreous Calcium-Alumino-Silicate). is

  10. Spectroscopic studies of irradiated glasses: Application in nuclear dosimetry

    International Nuclear Information System (INIS)

    The present work aims to study the effects of ionizing radiation on silicate glasses in order to develop a new dosimetry system simple, precise, stable and inexpensive. Indeed, changes in mechanical properties, optical and paramagnetic glasses when subjected to ionizing radiation. The prediction of long-term behavior, physical aging under irradiation, the glass is paramount. many studies have brought many ways to avoid obscuring glass windows used in nuclear reactors or hot cells and optical devices. Recently, much work has concentrated on the application of the color induced by irradiation for developing a recyclable glass in the glass industry is of great interest economically and environmentally.

  11. Effect of silicate pretreatment, post-sealing and additives on corrosion resistance of phosphated galvanized steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Sodium silicate (water glass) pretreatment before phosphating, silicate post-sealing after phosphating and adding silicate to a traditional phosphating solution were respectively carried out to obtain the improved phosphate coatings with high corrosion resistance and coverage on hot-dip galvanized(HDG) steel. The corrosion resistance, morphology and chemical composition of the coatings were investigated using neutral salt spray(NSS) tests, scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). The results show that pretreatment HDG steel with silicate solutions, phosphate coatings with finer crystals and higher coverage are formed and the corrosion resistance is enhanced. Adding silicate to a traditional phosphating solution, the surface morphology of the coatings is nearly unchanged. The corrosion resistance of the coatings is mainly dependent on phosphating time.Phosphating for a longer time (such as 5 min), the corrosion resistance, increasing with concentration of silicate, is improved significantly. Post-sealing the phosphated HDG steel with silicate solutions, the pores among the zinc phosphate crystals are sealed with the films containing Si, P, O and Zn and the continuous composite coatings are formed. The corrosion resistance of the composite coatings, related to the pH value, contents of hydrated gel of silica and Si2O52- and post-sealing time, is increased markedly. The improved coatings with optimal corrosion resistance are obtained for phosphating 5 min and post-sealing with 5 g/L silicate solution for 10 min.

  12. Formation of Magnesium Silicates is Limited around Evolved Stars

    Science.gov (United States)

    Kimura, Yuki; Nuth, J. A., III

    2009-05-01

    Laboratory experiments suggest that magnesium silicide (Mg2Si) grains could be produced in the hydrogen dominant gas outflow from evolved stars in addition to amorphous oxide minerals. Astronomical observations have shown the existence of abundant silicate grains around evolved stars and we have long realized that most of the silicate grains are amorphous, based on the observed infrared features. Only high mass loss stars show the feature attributed to magnesium-rich crystalline silicate about 10-20 % respect to total silicates, so far. The lower degree of crystallinity observed in silicates formed in outflows of lower mass-loss-rate stars might be caused by the formation of magnesium silicide in this relatively hydrogen-rich environment. As a result of predominant distribution of magnesium into the silicide, the composition of interstellar amorphous silicates could be magnesium poor compared with silicon. Indeed, the chemical composition of isotopically anomalous GEMS (glass with embedded metal and sulfides) is magnesium poor with respect to a forsteritic composition (Floss et al. 2006; Keller & Messenger 2007). Infrared observations suggest that there is little or no crystalline forsterite in interstellar environments while there is an abundance of crystalline forsterite in our Solar System. If the forsterite is a result of the oxidation of interstellar magnesium silicide, then it is clear both why crystalline forsterite is stoichiometric olivine and why the chemical composition of isotopically anomalous GEMS is magnesium poor with respect to a forsteritic composition. In addition, it may also explain why the chemical composition of olivine is iron poor. Unfortunately, magnesium silicide has never been detected via astronomical observation or in the analysis of primitive meteorites. I would suggest that future analysis of meteorites and theoretical calculations could confirm the possibility of the formation of magnesium silicide grains around evolved stars.

  13. Irradiation effects in glasses

    International Nuclear Information System (INIS)

    The deposition of irradiation energy can alter the physical properties of glasses through bond-breaking (energetic photons; fast particles) and atomic displacements (Coulombic and collisional: n0, e, ions). These processes can alter UV-visible optical properties via electron-hole trapping and IR-spectra as a result of network damage. The movement of network atoms results in volume dilatation which change the hardness, refractive index, and dissolution rates. All of these changes can be realized with ion implantation and, in addition, implantation of chemically active species can lead to compound formation in the implanted regions. For this reason, emphasis will be placed on the implantation-induced surface modifications of glasses (mostly silicates). The paper includes crystallization, surface stress, refractive index changes and optoelectronic application and chemical reactivity

  14. Challenge of ASR in the Use of Waste Glass Slurry

    OpenAIRE

    Kara, P

    2014-01-01

    Currently the majority of industrial companies in the world develop and implements clean production technologies where manufacturing wastes are recycled and are used for new building materials production. Due glass debris sorting and recycling are practiced at minimum level in Latvia, there should be found alternative ways how to reduce the accumulated glass wastes. The worldwide application of waste glass in concrete was quite limited due to alkali-silica reactivity (ASR) for almost forty ye...

  15. Microstructural and Mechanical Properties of Alkali Activated Colombian Raw Materials

    Directory of Open Access Journals (Sweden)

    Maria Criado

    2016-03-01

    Full Text Available Microstructural and mechanical properties of alkali activated binders based on blends of Colombian granulated blast furnace slag (GBFS and fly ash (FA were investigated. The synthesis of alkali activated binders was conducted at 85 °C for 24 h with different slag/fly ash ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100. Mineralogical and microstructural characterization was carried out by means of X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX and Nuclear magnetic resonance (NMR. Mechanical properties were evaluated through the compressive strength, modulus of elasticity and Poisson’s ratio. The results show that two different reaction products were detected in the slag/fly ash mixtures, a calcium silicate hydrate with Al in its structure (C-A-S-H gel and a sodium aluminosilicate hydrate (N-A-S-H gel with higher number of polymerized species and low content in Ca. It was found that with the increase of the amount of added slag, the amount of C-A-S-H gel increased and the amount of N-A-S-H gel decreased. The matrix was more dense and compact with almost absence of pores. The predominance of slag affected positively the compressive strength, Young’s modulus and Poisson’s ratio, with 80% slag and 20% fly ash concrete being the best mechanical performance blend.

  16. Volume changes in glass induced by an electron beam

    International Nuclear Information System (INIS)

    Three glasses (float, borosilicate float and Schott D263 glasses) were irradiated by 50 keV electron beams with doses within the range of 0.21–318.5 kC/m2. Volume changes induced by electron bombarding were monitored by means of Atomic Force Microscopy. Incubation doses, related to mobility of alkali ions, were measured. Low doses showed compaction of all glasses while higher doses revealed volume inflation, except for borosilicate float glass. Both surfaces of float glass were irradiated and significant differences between them were found

  17. Solubility of a new calcium silicate-based root-end filling material

    OpenAIRE

    Shishir Singh; Rajesh Podar; Shifali Dadu; Gaurav Kulkarni; Rucheet Purba

    2015-01-01

    Introduction: The purpose of this study was to compare solubility of a new calcium silicate-based cement, Biodentine with three commonly used root-end filling materials viz. glass-ionomer cement (GIC), intermediate restorative material (IRM), and mineral trioxide aggregate (MTA). Materials and Methods: Twenty stainless steel ring molds were filled with cements corresponding to four groups (n = 5). The weight of 20 dried glass bottles was recorded. Samples were transferred to bottles conta...

  18. Glass sealing

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K.; Kovacic, L.; Chambers, R.S. [Sandia National Labs., Albuquerque, NM (United States)

    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.

  19. Use of Slag/Sugar Cane Bagasse Ash (SCBA) Blends in the Production of Alkali-Activated Materials

    OpenAIRE

    María V. Borrachero; Jordi Payá; José Monzó; Lourdes Soriano; Mauro M. Tashima; José L.P. Melges; Jorge L. Akasaki; Vinícius N. Castaldelli

    2013-01-01

    Blast furnace slag (BFS)/sugar cane bagasse ash (SCBA) blends were assessed for the production of alkali-activated pastes and mortars. SCBA was collected from a lagoon in which wastes from a sugar cane industry were poured. After previous dry and grinding processes, SCBA was chemically characterized: it had a large percentage of organic matter (ca. 25%). Solutions of sodium hydroxide and sodium silicate were used as activating reagents. Different BFS/SCBA mixtures were studied, replacing part...

  20. Stardust silicates from primitive meteorites.

    Science.gov (United States)

    Nagashima, Kazuhide; Krot, Alexander N; Yurimoto, Hisayoshi

    2004-04-29

    Primitive chondritic meteorites contain material (presolar grains), at the level of a few parts per million, that predates the formation of our Solar System. Astronomical observations and the chemical composition of the Sun both suggest that silicates must have been the dominant solids in the protoplanetary disk from which the planets of the Solar System formed, but no presolar silicates have been identified in chondrites. Here we report the in situ discovery of presolar silicate grains 0.1-1 microm in size in the matrices of two primitive carbonaceous chondrites. These grains are highly enriched in 17O (delta17O(SMOW) > 100-400 per thousand ), but have solar silicon isotopic compositions within analytical uncertainties, suggesting an origin in an oxygen-rich red giant or an asymptotic giant branch star. The estimated abundance of these presolar silicates (3-30 parts per million) is higher than reported for other types of presolar grains in meteorites, consistent with their ubiquity in the early Solar System, but is about two orders of magnitude lower than their abundance in anhydrous interplanetary dust particles. This result is best explained by the destruction of silicates during high-temperature processing in the solar nebula.

  1. Performance characterization of rigid polyurethane foam with refined alkali lignin and modified alkali lignin

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-ming; YU Fei; FANG Gui-zhen; YANG Hui-jun

    2009-01-01

    The two kinds of rigid polyurethane (PU) foams were prepared with respectively adding the refined alkali lignin and alkali lignin modified by 3-chloro-1,2-epoxypropane to be instead of 15% of the polyether glycol in weight. The indexes of mechanical performance, apparent density, thermal stability and aging resistance were separately tested for the prepared PU foams. The results show that the mechanical property, thermal insulation and thermal stability for PU foam with modified alkali lignin are excellent among two kinds of PU foams and control samples. The additions of the refined alkali lignin and modified alkali lignin to PU foam have little effect on the natural aging or heat aging resistance except for decreasing hot alkali resistance apparently. Additionally, the thermal conductivity of modified alkali lignin PU foam is lowest among two kinds of PU foams and control samples. The alkali lignin PU foam modified by 3-chloro-1,2-epoxypropane could be applied in the heat preservation field.

  2. Identifying glass compositions in fly ash

    Science.gov (United States)

    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.

  3. Identifying glass compositions in fly ash

    Directory of Open Access Journals (Sweden)

    Katherine eAughenbaugh

    2016-01-01

    Full Text Available 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.

  4. PIXE/PIGE characterization of medieval glass

    International Nuclear Information System (INIS)

    The glasses of Ljubljana, related historically to the spread of glassworks in the Venetian style, were studied by a combined PIXE/PIGE method based on the in-air proton beam. The contribution of PIGE was determination of Na, Mg and Al oxides that provided (1) non-ambiguous characterization of the alkali and limestone component, (2) stable concentration evaluation algorithm relying on the normalization of all metal oxides to 100%. The majority of investigated samples form a compact group with small variations due to the alkalis used; a clear distinction from a few imported objects confirms local production. The raw materials in medieval glassworks differ significantly from those of Late Antiquity

  5. Preparation and characterization of a PbO protective glass

    International Nuclear Information System (INIS)

    The study of the binary system of lead silicate glass PbO-SiO2, and particularly the glasses having more than 80% of PbO and no alkaline oxides allows to answer to some preoccupations and requirements towards these glasses, in particular their transparencies and their attenuation power, on account of the high values of the refractive index and the density of these glasses. Radiation protection is a field which concerns all the countries of the world including Algeria; this country is then concerned by the import of this product used in hospitals for instance. On account of the importance of this glass and of its wide application domain, it is interesting to study it in order to be able to manufacture it in Algeria and to improve its properties. The aim of this work is then to prepare different lead silicate glasses allowing a maximal absorption of the ionizing radiations. (O.M.)

  6. The Glass and Jade Road-the Cultural and Technical Exchange of Silicate Based Artefacts with Foreign Countries Before Qin Dynasty%玻璃和玉石之路—兼论先秦硅酸盐质文物的中、外文化和技术交流

    Institute of Scientific and Technical Information of China (English)

    干福熹

    2013-01-01

    nondestructive analysis belonged to soda-lime silicate system.By comparing the decorative design and application of colour agent,we found that the ancient eye-beads unearthed in Xichuan and Sui countries were imported from the ancient Egypt,which could promote the glass compound (eye) bead making technology in the ancient China.The sources of ancient Chinese Jade stones and pigment materials,as well as their exchange with foreign countries were discussed in this paper.By analyzing the material origin,sources and application of jade stones of nephrite,turquoise and lapis lazuli,we considered that the ancient pigment materials of lapis lazuli was came from Afghanistan,and the turquoise jade stones were possibly imported from Persia (i.e.,ancient Iran).The suddenly increase of the jade artefacts of nephrite with tremolite mineral between Xia and Shang Dynasties indicated that the nephrite minerals came from a new source,probably from Hetian,Xinjiang,China.According to the archaeological materials,a road map of transportation of ancient glasses and jade stones from West to East in 1 500~500 B.C.was proposed,showing the ancient steppe road connected Western Asia and Central Asia with Inner China.The movement of steppe nomad tribes and technical exchange in Eurasia in the proto-history period was also discussed.

  7. Topological Principles of Borosilicate Glass Chemistry

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Mauro, J. C.; Youngman, R. E.;

    2011-01-01

    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...... earthborosilicate 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...

  8. Glass capable of ionic conduction and method of preparation

    Science.gov (United States)

    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.

  9. Spectroscopic Properties of Nd3+-Doped High Silica Glass Prepared by Sintering Porous Glass

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new kind of Nd3+-doped high silica glass (SiO2>96% (mass fraction)) was obtained by sintering porous glass impregnated with Nd3+ ions. The absorption and luminescence properties of high silica glass doped with different Nd3+ concentrations were studied. The intensity parameters Ωt (t=2, 4, 6), spontaneous emission probability, fluorescence lifetime, radiative quantum efficiency, fluorescence branching ratio, and stimulated emission cross section were calculated using the Judd-Ofelt theory. The optimal Nd3+ concentration in high silica glass was 0.27% (mole fraction) because of its high quantum efficiency and emission intensity. By comparing the spectroscopic parameters with other Nd3+-doped oxide glasses and commercial silicate glasses, the Nd3+-doped high silica glasses are likely to be a promising material used for high power and high repetition rate lasers.

  10. NON-AUTOCLAVE SILICATE BRICK

    Directory of Open Access Journals (Sweden)

    V. N. Yaglov

    2015-01-01

    Full Text Available The paper proposes a technology for obtaining bricks on the basis of lime-silica mixtures where chemical interactions are practically completely realized in dispersive state at the stage of preparation of binding contact maturing and raw mixture as a whole. The role of forming operation (moulding is changed in principle because in this case conversion of dispersive system into a rock-like solid occurs and due to this the solid obtains complete water-resistance in contact with water immediately after forming operation. Theoretical basis for the developed technology is capability of silicate dispersive substances (hydrated calcium silicate to transit in non-stable state, to form a rock-like water-resistant solid in the moment of mechanical load application during forming process. Specific feature of the proposed method is an exclusion of additional operations for autoclaving of products from the process of obtaining a silicate brick.Synthetic hydrated calcium silicate in contrast to natural ones are more uniform in composition and structure, they contain less impurities and they are characterized by dispersive composition and due to the mentioned advantages they find wider practical application. Contact-condensation binders permit to manipulate product properties on their basis and ensure maximum correspondence to the requirements of the concrete application. Raw material sources for obtaining synthetic hydrated calcium silicates are practically un-limited because calcium-silicon containing substances are found as in various technogenic wastes so in natural compounds as well. So the problem for obtaining hydrated calcium silicates having contact-condensation ability for structure formation becomes more and more actual one. This transition is considered as dependent principally on arrangement rate of substance particles which determined the level of its instability.

  11. Effect of silicate incorporation on in vivo responses of α-tricalcium phosphate ceramics.

    Science.gov (United States)

    Kamitakahara, Masanobu; Tatsukawa, Eri; Shibata, Yasuaki; Umemoto, Shota; Yokoi, Taishi; Ioku, Koji; Ikeda, Tohru

    2016-05-01

    In addition to calcium phosphate-based ceramics, glass-based materials have been utilized as bone substitutes, and silicate in these materials has been suggested to contribute to their ability to stimulate bone repair. In this study, a silicate-containing α-tricalcium phosphate (α-TCP) ceramic was prepared using a wet chemical process. Porous granules composed of silicate-containing α-TCP, for which the starting composition had a molar ratio of 0.05 for Si/(P + Si), and silicate-free α-TCP were prepared and evaluated in vivo. When implanted into bone defects that were created in rat femurs, α-TCP ceramics either with or without silicate were biodegraded, generating a hybrid tissue composed of residual ceramic granules and newly formed bone, which had a tissue architecture similar to physiological trabecular structures, and aided regeneration of the bone defects. Supplementation with silicate significantly promoted osteogenesis and delayed biodegradation of α-TCP. These results suggest that silicate-containing α-TCP is advantageous for initial skeletal fixation and wound regeneration in bone repair. PMID:27003839

  12. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  13. Modelling The Effects of Aggregate Size on Alkali Aggregate Reaction Expansion

    Directory of Open Access Journals (Sweden)

    N. Z. Sekrane

    2014-06-01

    Full Text Available This work aims at developing models to predict the potential expansion of concrete containing alkali-reactive aggregates. The paper gives measurements in order to provide experimental data concerning the effect of particle size of an alkali-reactive siliceous limestone on mortar expansion. Results show that no expansion was measured on the mortars using small particles (0.5-1.0 mm while the particles (1.0–2.0 mm gave the largest expansions (0.217%. Two models are proposed, the first one studies the correlations between the measured expansions and the size of aggregates, the second one calculates the thickness of the porous zone necessary to take again all the volume of the gel created.

  14. Point defects in silicates

    International Nuclear Information System (INIS)

    Topaz is a wide band gap insulating crystal with four Al2F2SiO4 formula units per orthorhombic unit cell and containing isolated SiO4 tetrahedron. Electron spin resonance (ESR), UV-VIS spectrophotometry, photoluminescence, and isochronal annealing were used to study the point defects introduced by fast-neutron bombardment or by alpha decay recoils. The superoxide radical is characterized by a single hole-like spin 1/2 signal with principle g-values gxx = 2.0055, gzz = 2.0407 and the major axis of the defect points along 0.356a + 0.152b + 0.922c. The superoxide anneals near 650C. Two polarization dependent absorptions occur in the UV due to the transitions 2IIg → 2IIu and 2IIg → 2Δu. The former has an oscillator strength of 0.06. The 2.5 eV polarization dependent luminescence is due to the transition 2IIg → 2IIu. The 2Δu → 2IIu is non-radiative. The doubly occupied dangling silicon bond, the blue center, is characterized by a 2 eV polarization dependent absorption and is non-paramagnetic. The transition dipole for this absorption points in the direction 0.93a + 0.210b + 0.305c and the oscillator strength is approximately 2.0 x 10-3. The blue center anneals at 500C. This dangling bond defect is one of two models proposed for a similar 2 eV absorption in silica glass. The defects in quartz (SiO2) were introduced by the recoil nuclei after alpha decays of uranium, thorium, and their daughters in natural abundances. The accumulating damage provides a geological clock by which the age of the quartz can be found. The sample came from Yucca Flats, Nevada, the proposed site of a nuclear waste dump

  15. Fabrication and optical properties of lead silicate glass holey fibers

    OpenAIRE

    Ebendorff-Heidepriem, H.; Petropoulos, P.; Moore, R.; Frampton, K.; Monro, T.M.

    2003-01-01

    Since the first microstructured optical fiber was made in 1996, holey fibers (HFs) have attracted growing attention. Compared with conventional fibers, they offer a significantly broader range of optical properties such as photonic bandgap guiding, shift of anomalous dispersion into the visible, high nonlinearity in small core fibers and high power delivery in large mode area fibers. Therefore, HFs have a wide range of potential applications in optical technologies. The vast majority of resea...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...... 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....

  17. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO{sub 2}-coated carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Barrena, M.I., E-mail: ibarrena@quim.ucm.es [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain); Gomez de Salazar, J.M.; Soria, A.; Matesanz, L. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain)

    2011-11-15

    This work reported basically aims at understanding the extent of SiO{sub 2}-coated carbon nanofibers using two different sol-gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO{sub 2} precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

  18. Antibacterial Activity of Silicate Bioceramics

    Institute of Scientific and Technical Information of China (English)

    HU Sheng; NING Congqin; ZHOU Yue; CHEN Lei; LIN Kaili; CHANG Jiang

    2011-01-01

    Four kinds of pure silicate ceramic particles, CaSiO3, Ca3SiO5, bredigite and akermanite were prepared and their bactericidal effects were systematically investigated. The phase compositions of these silicate ceramics were characterized by XRD. The ionic concentration meas urement revealed that the Calcium (Ca) ion concentration were relatively higher in Ca3SiO5 and bredigite, and much lower in CaSiO3 and akermanite. Accordingly, the pH values of the four silicate ceramics extracts showed a positive correlation with the particle concentrations. Meanwhile, by decreasing the particle size, higher Ca ion concentrations can be achieved, leading to the increase of aqueous pH value as well. In summary, all of the four silicate ceramics tested in our study showed antibacterial effect in a dose-dependent manner. Generally, the order of their antibacterial activity against E.coli from strong to weak is Ca3SiO5, bredigite, CaSiO3 and akermanite.

  19. Amended Silicated for Mercury Control

    Energy Technology Data Exchange (ETDEWEB)

    James Butz; Thomas Broderick; Craig Turchi

    2006-12-31

    Amended Silicates{trademark}, a powdered, noncarbon mercury-control sorbent, was tested at Duke Energy's Miami Fort Station, Unit 6 during the first quarter of 2006. Unit 6 is a 175-MW boiler with a cold-side electrostatic precipitator (ESP). The plant burns run-of-the-river eastern bituminous coal with typical ash contents ranging from 8-15% and sulfur contents from 1.6-2.6% on an as-received basis. The performance of the Amended Silicates sorbent was compared with that for powdered activated carbon (PAC). The trial began with a period of baseline monitoring during which no sorbent was injected. Sampling during this and subsequent periods indicated mercury capture by the native fly ash was less than 10%. After the baseline period, Amended Silicates sorbent was injected at several different ratios, followed by a 30-day trial at a fixed injection ratio of 5-6 lb/MMACF. After this period, PAC was injected to provide a comparison. Approximately 40% mercury control was achieved for both the Amended Silicates sorbent and PAC at injection ratios of 5-6 lbs/MMACF. Higher injection ratios did not achieve significantly increased removal. Similar removal efficiencies have been reported for PAC injection trials at other plants with cold-side ESPs, most notably for plants using medium to high sulfur coal. Sorbent injection did not detrimentally impact plant operations and testing confirmed that the use of Amended Silicates sorbent does not degrade fly ash quality (unlike PAC). The cost for mercury control using either PAC or Amended Silicates sorbent was estimated to be equivalent if fly ash sales are not a consideration. However, if the plant did sell fly ash, the effective cost for mercury control could more than double if those sales were no longer possible, due to lost by-product sales and additional cost for waste disposal. Accordingly, the use of Amended Silicates sorbent could reduce the overall cost of mercury control by 50% or more versus PAC for locations where

  20. PREFACE: 5th Baltic Conference on Silicate Materials

    Science.gov (United States)

    Mezinskis, G.; Bragina, L.; Colombo, P.; Frischat, G. H.; Grabis, J.; Greil, P.; Deja, J.; Kaminskas, R.; Kliava, J.; Medvids, A.; Nowak, I.; Siauciunas, R.; Valancius, Z.; Zalite, I.

    2011-12-01

    Logo This Volume of IOP Conference Series: Materials Science and Engineering presents a selection of the contributions to the 5th Baltic Conference on Silicate Materials (BaltSilica2011) held at Riga Technical University, Riga, Latvia from 23-25 May 2011. The conference was organized by Riga Technical University (Latvia) and Kaunas University of Technology (Lithuania). The series of Baltic conferences on silicate materials was started since 2004: the first conference was held in Riga, Latvia, 2004; the second conference was held in Kaunas, Lithuania 2005; the third was held again in Riga, Latvia, 2007, and the fourth was held in Kaunas, Lithuania 2009. BaltSilica 2011 was attended by around 50 participants from Latvia, Lithuania, Estonia, Germany, Poland, Italy, France, Ukraine and Russia. In comparison with previous silicate materials conferences, the broadening of participating countries is an indication of the interest of scientists, engineers and students to exchange research ideas, latest results, and to find new research topics for cooperation in the fields of silicate, high temperature materials, and inorganic nanomaterials. The scientific programme included 8 invited plenary lectures 23 oral presentations and 25 posters [1]. Scientific themes covered in the conference and in this special issue: Natural and Artificial Stone Materials; Traditional and New Ceramic and Glass-Like Materials; Nanoparticles and Nanomaterials. This volume consists of 23 selected proceeding papers. The Editor of this special issue is grateful to all the contributors to BaltSilica 2011. I am also very grateful to the scientific committee, the local organizing committee, the session chairs, the referees who refereed the submitted articles to this issue, and to students from the Department of Silicate, High Temperature and Inorganic Nanomaterials Technology of the Riga Technical University who ensured the smooth running of the conference. Particular thanks goes to eight plenary

  1. 21 CFR 182.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2227 Calcium silicate. (a) Product. Calcium silicate....

  2. 21 CFR 582.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

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

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James Gordon [ORNL; Smith, Jeffrey D [ORNL; O' Hara, Kelley [University of Missouri, Rolla; Rodrigues-Schroer, Angela [Minteq International, Inc.; Colavito, [Minteq International, Inc.

    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

  4. Enhanced broadband near-infrared luminescence of Bi-doped oxyfluoride glasses.

    Science.gov (United States)

    Xu, Beibei; Tan, Dezhi; Zhou, Shifeng; Hong, Zhanglian; Sharafudeen, Kaniyarakkal N; Qiu, Jianrong

    2012-12-17

    Broadband near-infrared luminescence covering 900 to 1600 nm has been observed in Bi-doped oxyfluoride silicate glasses. The partial substitution of fluoride for oxide in Bi-doped silicate glasses leads to an increase of the intensity and lifetime of the near-infrared luminescence and blue-shift of the near-infrared emission peaks. Both Bi-doped silicate and oxyfluoride silicate glasses show visible luminescence with blue, green, orange and red emission bands when excited by ultra-violet light. Careful investigation on the luminescence properties indicates that the change of near-infrared luminescence is related to optical basicity, phonon energy of the glass matrix and crystal field around Bi active centers. These results offer a valuable way to control the luminescence properties of Bi-doped materials and may find some applications in fiber amplifier and fiber laser. PMID:23263148

  5. Thermophysical and structural studies on some glass-ceramics and role of nano size crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Kothiyal, G P; A, Arvind; Kumar, Rakesh; Dixit, Anupam; Sharma, Kuldeep; Goswami, Madhumita, E-mail: gpkoth@barc.gov.in [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400-085 (India)

    2009-07-15

    In this paper, we present some studies on structure and thermophysical properties of glass and glass-ceramics with possible bio-medical and sealing applications. The glass-ceramics prepared for bio-medical applications include phosphate as well as silico-phosphate compositions. In vitro bio-compatibility/activity of these materials is discussed. The glass-ceramics used for the sealing application are lithium aluminium silicate (LAS) and lithium zinc silicate (LZS). The phase formation and some aspects of thermophysical properties and sealing are discussed.

  6. Thermophysical and structural studies on some glass-ceramics and role of nano size crystallites

    International Nuclear Information System (INIS)

    In this paper, we present some studies on structure and thermophysical properties of glass and glass-ceramics with possible bio-medical and sealing applications. The glass-ceramics prepared for bio-medical applications include phosphate as well as silico-phosphate compositions. In vitro bio-compatibility/activity of these materials is discussed. The glass-ceramics used for the sealing application are lithium aluminium silicate (LAS) and lithium zinc silicate (LZS). The phase formation and some aspects of thermophysical properties and sealing are discussed.

  7. Silicate Composition of the Interstellar Medium

    CERN Document Server

    Fogerty, Shane; Watson, Dan M; Sargent, Benjamin A; Koch, Ingrid

    2016-01-01

    The composition of silicate dust in the diffuse interstellar medium and in protoplanetary disks around young stars informs our understanding of the processing and evolution of the dust grains leading up to planet formation. Analysis of the well-known 9.7{\\mu}m feature indicates that small amorphous silicate grains represent a significant fraction of interstellar dust and are also major components of protoplanetary disks. However, this feature is typically modelled assuming amorphous silicate dust of olivine and pyroxene stoichiometries. Here, we analyze interstellar dust with models of silicate dust that include non-stoichiometric amorphous silicate grains. Modelling the optical depth along lines of sight toward the extinguished objects Cyg OB2 No. 12 and {\\zeta} Ophiuchi, we find evidence for interstellar amorphous silicate dust with stoichiometry intermediate between olivine and pyroxene, which we simply refer to as "polivene." Finally, we compare these results to models of silicate emission from the Trapez...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Polymer-Layer Silicate Nanocomposites

    DEFF Research Database (Denmark)

    Potarniche, Catalina-Gabriela

    with a spectacular improvement up to 300 % in impact strength were obtained. In the second part of this study, layered silicate bio-nanomaterials were obtained starting from natural compounds and taking into consideration their biocompatibility properties. These new materials may be used for drug delivery systems......Nowadays, some of the material challenges arise from a performance point of view as well as from recycling and biodegradability. Concerning these aspects, the development of polymer layered silicate nanocomposites can provide possible solutions. This study investigates how to obtain polymer layered...... toughness-stiffness requirements. The new compatibilizer system used to obtain nanocomposites, presented an improvement of 8-20 % in tensile strength, 15-34 % in Young’s modulus, 23-34 % in fatigue tests and 20-58% in degree of crystalline phase. By introducing a rubbery phase as modifier, nanocomposites...

  10. Biogenic silicate accumulation in sediments, Jiaozhou Bay

    Institute of Scientific and Technical Information of China (English)

    LI Xuegang; SONG Jinming; DAI Jicui; YUAN Huamao; LI Ning; LI Fengye; SUN Song

    2006-01-01

    It has been widely recognized that low silicate content in seawater is a major limiting factor to phytoplankton primary production in Jiaozhou Bay. However the reason of Si-limitation remains poorly understood. In the present study we measured the biogenic silicate content and discussed the accumulation of silicate in Jiaozhou Bay sediment. The results show that the biogenic silica content in the sediment of the Jiaozhou Bay is obviously much higher than those in the Yellow Sea and the Bohai Sea. The BSi:TN ratios and BSi:16P ratios in the sediment are > 1 and the OC:BSi ratio in sediment is lower than these of Redfield ratio (106:16), indicating that the decomposition rate of OC is much higher than that for BSi in similar conditions. Therefore, the majority of the biogenic silicate was buried and thus did not participate in silicate recycling. Silicate accumulation in sediment may explain why Si limits the phytoplankton growth in the Jiaozhou Bay. Comparing the flux of biogenic silicate from sediments with primary production rate, it can be concluded that only 15.5% of biogenic silicate is hydrolyzed during the journey from surface to bottom in seawater, thus approximate 84.5% of biogenic silicate could reach the bottom. The silicate releasing rate from the sediment to seawater is considerably lower than that of sedimentation of biogenic silicate, indicating silicate accumulation in sediment too. In a word, the silicate accumulation in sediment is the key reason of silicate limiting to phytoplankton growth in Jiaozhou Bay.

  11. Modifying Silicates for Better Dispersion in Nanocomposites

    Science.gov (United States)

    Campbell, Sandi

    2005-01-01

    An improved chemical modification has been developed to enhance the dispersion of layered silicate particles in the formulation of a polymer/silicate nanocomposite material. The modification involves, among other things, the co-exchange of an alkyl ammonium ion and a monoprotonated diamine with interlayer cations of the silicate. The net overall effects of the improved chemical modification are to improve processability of the nanocomposite and maximize the benefits of dispersing the silicate particles into the polymer. Some background discussion is necessary to give meaning to a description of this development. Polymer/silicate nanocomposites are also denoted polymer/clay composites because the silicate particles in them are typically derived from clay particles. Particles of clay comprise layers of silicate platelets separated by gaps called "galleries." The platelet thickness is 1 nm. The length varies from 30 nm to 1 m, depending on the silicate. In order to fully realize the benefits of polymer/silicate nanocomposites, it is necessary to ensure that the platelets become dispersed in the polymer matrices. Proper dispersion can impart physical and chemical properties that make nanocomposites attractive for a variety of applications. In order to achieve nanometer-level dispersion of a layered silicate into a polymer matrix, it is typically necessary to modify the interlayer silicate surfaces by attaching organic functional groups. This modification can be achieved easily by ion exchange between the interlayer metal cations found naturally in the silicate and protonated organic cations - typically protonated amines. Long-chain alkyl ammonium ions are commonly chosen as the ion-exchange materials because they effectively lower the surface energies of the silicates and ease the incorporation of organic monomers or polymers into the silicate galleries. This completes the background discussion. In the present improved modification of the interlayer silicate surfaces

  12. Manufacture of nitrogen-containing crystalline metal silicates having a zeolite structure

    Energy Technology Data Exchange (ETDEWEB)

    Marosi, L.; Schwarzmann, M.; Stabenow, J.

    1984-06-26

    A process is claimed for the manufacture of a nitrogen-containing crystalline metal silicate having a zeolite structure from silicon dioxide and a metal oxide and/or metal hydroxide, wherein the crystallization is carried out in the absence of an alkali metal in an aqueous solution of hexamethylenediamine, preferably under the autogeneous pressure of the solution at from 100/sup 0/ to 200/sup 0/ C. The zeolites are preferably used as catalysts for the reaction of methanol and/or dimethyl ether to give unsaturated hydrocarbons, the oligomerization of olefins, the alkylation of aromatics, and other conversions of hydrocarbons.

  13. PMR-15/Layered Silicate Nanocomposites For Improved Thermal Stability And Mechanical Properties

    Science.gov (United States)

    Campbell, Sandi; Scheiman, Daniel; Faile, Michael; Papadopoulos, Demetrios; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Montmorillonite clay was organically modified by co-exchange of an aromatic diamine and a primary alkyl amine. The clay was dispersed into a PMR (Polymerization of Monomer Reactants)-15 matrix and the glass transition temperature and thermal oxidative stability of the resulting nanocomposites were evaluated. PMR-15/ silicate nanocomposites were also investigated as a matrix material for carbon fabric reinforced composites. Dispersion of the organically modified silicate into the PMR-15 matrix enhanced the thermal oxidative stability, the flexural strength, flexural modulus, and interlaminar shear strength of the polymer matrix composite.

  14. Polymer/Silicate Nanocomposites Developed for Improved Thermal Stability and Barrier Properties

    Science.gov (United States)

    Campbell, Sandi G.

    2001-01-01

    The nanoscale reinforcement of polymers is becoming an attractive means of improving the properties and stability of polymers. Polymer-silicate nanocomposites are a relatively new class of materials with phase dimensions typically on the order of a few nanometers. Because of their nanometer-size features, nanocomposites possess unique properties typically not shared by more conventional composites. Polymer-layered silicate nanocomposites can attain a certain degree of stiffness, strength, and barrier properties with far less ceramic content than comparable glass- or mineral-reinforced polymers. Reinforcement of existing and new polyimides by this method offers an opportunity to greatly improve existing polymer properties without altering current synthetic or processing procedures.

  15. Immobilisation and solidification of cesium on 11 A calcium silicate hydroxy hydrate column

    International Nuclear Information System (INIS)

    Calcium silicate hydrate closely resembling silicate mineral 11 A tobermorite has been synthesised by hydrothermal treatment of lime and silica at 175 degC. The synthetic mineral exhibits selectivity for Cs+ in the presence of strong solutions of alkali and alkaline earth cations, viz, Na+, K+, Mg2+, Ca2+, Sr2+, etc. The Al-substituted form of this mineral effectively separates cesium ion when used as an exchanger in column of size 35x5 mm (hxr). It is possible to remove 98.65±0.5%Cs+ from a mixed solution of cesium and sodium (0.0001N Cs+ + 0.5N Na+). Column separation of cesium from simulated intermediate level waste solution shows that from the first run ∼ 76% Cs+ can be immobilised on a small column, 18x10mm (hxr), having 2.0 g of exchanger. (author)

  16. Glass production in Late Antiquity and the Early Islamic period: a geochemical perspective

    OpenAIRE

    Freestone, I. C.

    2006-01-01

    First millennium AD glass production was divided between a relatively small number of workshops that made raw glass and a large number of secondary workshops that fabricated vessels. Glass compositions reflect the primary glassmaking source. For most of the period, Egyptian mineral soda was fused with lime-bearing siliceous sand to produce soda-lime-silica glass. The location of the Belus glassmaking sand, which is known from the classical literature, is located on that part of the Levantine ...

  17. Effects of Modulus and Modifying Agent on Aging of Water Glass

    Directory of Open Access Journals (Sweden)

    Xu Hailan

    2016-01-01

    Full Text Available This paper studied the content of water glass before and after adding modifying agent by TMS-GC method, it was found that different modulus of water glass led to decrease of silicate content at different levels after a period of storage, and the modifying agent could retard the aging of water glass. It has remarkable significance on the theory and practical application of water glass chemistry.

  18. Advancements in flowing diode pumped alkali lasers

    Science.gov (United States)

    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.

  19. The Impact of the Source of Alkali on Sludge Batch 3 Melt Rate

    International Nuclear Information System (INIS)

    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 Na2O 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 Na2O-rich frit to a Na2O-deficient frit while compensating the Na2O content in the sludge to maintain the same overall Na2O 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 % Na2O (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% Na2O feed) or the frit (the 0% Na2O 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 SMRF melt rate of the baseline feed. The SOA

  20. Modification of resin modified glass ionomer cement by addition of bioactive glass nanoparticles.

    Science.gov (United States)

    Valanezhad, Alireza; Odatsu, Tetsuro; Udoh, Koichi; Shiraishi, Takanobu; Sawase, Takashi; Watanabe, Ikuya

    2016-01-01

    In the present study, sol-gel derived nanoparticle calcium silicate bioactive glass was added to the resin-modified light cure glass-ionomer cement to assess the influence of additional bioactive glass nanoparticles on the mechanical and biological properties of resin-modified glass-ionomer cement. The fabricated bioactive glass nanoparticles added resin-modified glass-ionomer cements (GICs) were immersed in the phosphate buffer solution for 28 days to mimic real condition for the mechanical properties. Resin-modified GICs containing 3, 5 and 10 % bioactive glass nanoparticles improved the flexural strength compared to the resin-modified glass-ionomer cement and the samples containing 15 and 20 % bioactive glass nanoparticles before and after immersing in the phosphate buffer solution. Characterization of the samples successfully expressed the cause of the critical condition for mechanical properties. Cell study clarified that resin-modified glass-ionomer cement with high concentrations of bioactive glass nanoparticles has higher cell viability and better cell morphology compare to control groups. The results for mechanical properties and toxicity approved that the considering in selection of an optimum condition would have been a more satisfying conclusion for this study.