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1
Pan, Qun, Bin Zhu, Xiao Huang et Lin Liu. « Properties of Alkli-Activated Slag Cement Compounded with Soluble Glasses with a High Silicate Modulus ». Advanced Materials Research 712-715 (juin 2013) : 905–8. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.905.
Texte intégralRésumé :
Properties of alkali-activated slag cements compounded with soluble glasse with a high silicate modulus Ms=2.6 were detailedly studied in this paper, including compressive strength and flexure strength characterictics at the ages of 3,7,28 days and flow values of fresh cement mixtures on a jolting table. As a result, with the compressive strength at the age of 28 days of 95.6-107.8 MPa has been developed, and the flow values and strength characteristics of alkali-activated slag cement mortars increased with increase in a water to cement (alkaline activator solution to slag) ratio, and the flow value (determined on the cement mortar mixtures) would reach 145 mm. Moreover, the development speed of strength characteristics of mortar specimens would be affected negatively by increasing of water demand (requirement).
2
Möncke, Doris, Brian Topper et Alexis G. Clare. « Glass as a State of Matter—The “newer” Glass Families from Organic, Metallic, Ionic to Non-silicate Oxide and Non-oxide Glasses ». Reviews in Mineralogy and Geochemistry 87, no 1 (1 mai 2022) : 1039–88. http://dx.doi.org/10.2138/rmg.2022.87.23.
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OVERVIEW In theory, any molten material can form a glass when quenched fast enough. Most natural glasses are based on silicates and for thousands of years only alkali/alkaline earth silicate and lead-silicate glasses were prepared by humankind. After exploratory glass experiments by Lomonosov (18th ct) and Harcourt (19th ct), who introduced 20 more elements into glasses, it was Otto Schott who, in the years 1879–1881, melted his way through the periodic table of the elements so that Ernst Abbe could study all types of borate and phosphate glasses for their optical properties. This research also led to the development of the laboratory ware, low alkali borosilicate glasses. Today, not only can the glass former silicate be replaced, partially or fully, by other glass formers such as oxides of boron, phosphorous, tellurium or antimony, but also the oxygen anions can be substituted by fluorine or nitrogen. Chalcogens, the heavier ions in the group of oxygen in the periodic table (S, Se, Te), on their own or when paired with arsenic or germanium, can function as glass formers. Sulfate, nitrate, tungstate and acetate glasses lack the conventional anion and cation classification, as do metallic or organic glasses. The latter can occur naturally—amber predates anthropogenic glass manufacture by more than 200 million years. In this chapter, we are going to provide an overview of the different glass families, how the structure and properties of these different glass types differ from silicate glasses but also what similarities are dictated by the glassy state. Applications and technological aspects are discussed briefly for each glass family.
3
Ramamurthy, Sundar, Brian C. Hebert et C. Barry Carter. « Olivine-MgO interfaces produced by crystallization of glass fulms on single-crystal MgO substrates ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 342–43. http://dx.doi.org/10.1017/s0424820100138087.
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Glassy silicates are present at grain boundaries in almost all liquid-phase sintered ceramic oxides. In many cases, the amorphous-crystalline interfaces in the sintered microstructure can be modified by inducing crystallization of the glassy phase. The intergranular phases in polycrystalline MgO are typically silicates with cations of calcium, magnesium and iron in the silicate network. A systematic approach to study the crystallization behavior of glass-MgO interfaces has been attempted in the present study. Following the work by Mallamaci in which crystallization of a silicate glass in contact with A12O3 was studied, devitrification of glass in contact with single-crystal MgO has been investigated. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the resulting microstructures.A pellet of Mg2SiO4 (forsterite) prepared by hot-pressing MgO and SiO2 powders was used as the target for depositing glass films onto single-crystal MgO substrates by pulsed-laser deposition (PLD). Glass films with the composition of olivine.
4
Yanina, Svetlana V., Matthew T. Johnson, Zhigang Mao et C. Barry Carter. « On Devitrification of Monticellite (CaMgSiO4) Films Grown on (001)-Oriented Single-Crystal MgO. » Microscopy and Microanalysis 4, S2 (juillet 1998) : 590–91. http://dx.doi.org/10.1017/s1431927600023072.
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Silicate glasses are the most common constituents of intergranular phases which can be found in liquid-phase sintered ceramics [1]. Silicates are known to influence the structure of ceramic interfaces which, in turn, frequently affect mechanical properties of ceramic materials [2]. In earlier studies of silicate glasses on single-crystal alumina Ramamurthy et al [3] and Mallamaci [4] showed that the morphology of dewetted glass films and the mechanism of devitrification depend on the crystallographic orientation of the substrate surface. In continuation of these studies, results are presented on the dewetting behavior of monticellite (CaMgSi04) in contact with the (OOl)-oriented surface of single-crystal MgO. Due to the simplicity of sample preparation and availability of 3- dimensional topographic information, Atomic Force Microscopy (AFM) was used for surface characterization. These AFM results are complemented by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) data on the chemical composition and the structure of the glass-substrate interface.
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Vaiborisut, Napaporn, Chanittha Chunwises, Dararat Boonbundit, Sirithan Jiemsirilers et Apirat Theerapapvisetpong. « Effect of the Addition of ZrSiO4 on Alkali-Resistance and Liquidus Temperature of Basaltic Glass ». Key Engineering Materials 766 (avril 2018) : 145–50. http://dx.doi.org/10.4028/www.scientific.net/kem.766.145.
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Basalt fiber has been used as a reinforced material in cement-based materials because it has higher mechanical strength and cheaper than common silicate based glass-fibers. However, silicate-based glass fibers have low alkali resistance especially in cement matrix composite. In this work, we studied the improvement of alkali resistance by addition of zirconium silicate (ZrSiO4) in original basalt glass composition. The batch of basalt glass with additional ZrSiO4 contents of 0.00, 2.50, 5.00, 7.50 and 10.00 wt% were melted at 1500 °C. The liquidus temperature (TL) is important in for the fiber glass manufacturing. It need to formulate glass composition which requires a lower melting temperature and is crystallization resistant. TL as a function of composition is usually determined experimentally. In this study, glassy phase was determined by X-ray Diffraction (XRD). The glass transition temperature (Tg), the crystallization temperature (Tc) and TL were analyzed by Differential Thermal Analysis (DTA). The results found that the addition of ZrSiO4 in a basalt glass batch increased Tg while Tc of each sample was closed to original basalt fiber. Moreover, the alkali resistance of these glasses increased with an increasing of ZrSiO4 content. However, excessive ZrSiO4 contents (7.50 and 10.00 wt%) resulted in crystallization of ZrO2 which separated from glassy phase.
6
Vaisman, Ya I., I. S. Glushankova, Yu A. Ketov, L. V. Rudakova et M. P. Krasnovskikh. « Recovery of Sulfur-Alkaline Waste by Processing into Cellular Silicate Material ». Ecology and Industry of Russia 22, no 10 (5 octobre 2018) : 24–27. http://dx.doi.org/10.18412/1816-0395-2018-10-24-27.
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The formation of cellular silicate glasses from sulfide-alkaline solutions and amorphous silicon oxide has been studied. The mechanism of formation of silicates from sodium hydroxide and amorphous silicon oxide and processes of gasification with the participation of the organic component of waste are considered. Technological solutions for recovery of sulfide-alkaline solutions are proposed. At the same time, the process of recovery consists in mixing sulfuralkaline waste with natural amorphous silicon oxide, tripoli, and further roasting the resulting composition at glass formation temperatures. As a result of heat treatment, sulfur from organosulfur compounds is oxidized to sulfur (IV), and sodium hydroxide, after dehydration, enters in composition of the resulting vitreous silicate cellular material.
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da Silva, Antônio Carlos, S. C. Santos et Sonia Regina Homem de Mello-Castanho. « Transition Metals in Glass Formation ». Materials Science Forum 727-728 (août 2012) : 1496–501. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.1496.
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The structure of silicate glasses gets its charge stability through SiO2, R2O3, R2+and R+groups arrangement. In these glassy structures, transition metals are usually used as dopants in small amounts. However, in soda-lime glass systems, transition metals can take part in the glassy network in larger quantities as secundary former or modifier, insted R2+groups, if the charge balance conditions are made favorable by R2O3groups additions. This paper studies transition metals (Cr, Ni, Fe, Cu, Zn, Pb, Ru) soda-lime-borosilicate glass network incorporation. This process was applied for many kinds of toxic metals containing vitrification waste. The glasses were obtaind by melt at temperature of 1300°C, and characterized by FT-IR and XRD techinics. The chemical stability was evaluated by hydrolytic attack test. The glasses showed a high chemistry and environmental stability like the soda-lime glass.Keywords: glass structure, electroplating waste, e-waste, nanowaste.
8
Saakyan, Emma, Artavazd Arzumanyan et Gagik Galstyan. « New Energy Efficient Technology of Cellular Glass ». Key Engineering Materials 828 (décembre 2019) : 146–52. http://dx.doi.org/10.4028/www.scientific.net/kem.828.146.
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On the base of volcanic glass - perlite, the energy-efficient technology of cellular glass for heat-insulating purposes has been developed. Compositions of nanosized modifier and redox gas formers were developed by the method of experimental-statistical modeling and optimization of probability parameters, allowing to obtain cellular glasses with low average density and almost closed porosity in a single technological process at technologically acceptable temperatures. In the production of cellular glasses (foam glass) of new generation, based on natural glassy rocks of silicate and aluminosilicate composition modified with sodium hydroxide, in the presence of water and gas-forming additives, during mixing and sintering, the components react at the nanoscale level to form glass under low softening temperature and sufficient quantity of foam stabilizers. The main scientific results - the use of nanotechnological modification of amorphous silicate and aluminosilicate rocks in the technology of cellular glass for construction and technical purposes, the development of compositions and method for the production of cellular glass using energy-saving technology with the following performance parameters: average density of 115...250kg/m3, coefficient of thermal conductivity 0,051...0.075W/(m•K), water absorption 1.6...4.0%, compressive strength 0.14...4.20 MPa, hydrolytic glass class I...III.
9
Chen, Lu, et Ying Dai. « Effects of Iron Oxide on the Crystallization of Calcium Alumino-Silicate Glass ». Key Engineering Materials 680 (février 2016) : 293–96. http://dx.doi.org/10.4028/www.scientific.net/kem.680.293.
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Different amounts of iron oxide (Fe2O3) were added into a base calcium alumino-silicate glass (CaO 40, Al2O3 9, SiO2 51 wt%). The crystallization behavior of the glassed was investigated by DTA, XRD, SEM and optical microscopy. DTA analysis on the samples with and without the iron additions shows that the iron-containing glasses obviously absorb more heat energy than the base glass. All the glasses show two endothermal peaks correspondent to two transition temperatures, Tg1 and Tg2, indicating the existence of phase separation. Compared with the base glass, an initial addition of 5wt% Fe2O3 does not result in significant changes in Tg1, but a large decrease in Tg2 is observed. Further additions of 10 and 15wt% Fe2O3, both Tg1 and Tg2 decreases. The iron-containing glasses show two crystallization peaks in their DTA curves. Fe2O3 facilitates the crystallization of the calcium alumino-silicate glass indicated by the decreased activation energy and increased Avrami exponent. SEM observations evidenced that the crystallintes in the heat treated samples are nanosized. It is evidenced that the base glass and the glasses containing 5 and 10 wt% Fe2O3 are surface crystallized upon heat-treatment and the main crystalline phase is wollastonite. The surface crystallization layer and the grain size increase with Fe2O3. However, an addition of 15wt% Fe2O3 results in a bulk crystallization leading to the formation of iron-and aluminum-containing phases.
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Lu, An Xian, S. J. Liu, X. D. Tang et S. B. He. « Difference of Properties between Yb3+-Doped Silicate and Phosphate Laser Glasses ». Advanced Materials Research 11-12 (février 2006) : 213–16. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.213.
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The Yb3+-doped silicate and phosphate laser glasses were prepared by using of traditional melt quenching technology, and the physical and spectral properties were investigated. The results show that the stimulated emission cross section and the fluorescence lifetime are 0.67×10-20cm2 and 1200μs for the silicate glass, and 0.75×10-20cm2 and 1000μs for the phosphate glass respectively. And silicate glass’s mechanical and thermal properties were better than that of phosphate glass. But Yb3+-doped phosphate glass has lower nonlinear refraction index n2. Both Yb3+-doped silicate and phosphate glasses are possible to be used as laser medium.
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Mallamaci, Michael P., James Bentley et C. Barry Carter. « In situ crystallization of silicate glass films deposited on α-Al2O3 ». Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 août 1993) : 928–29. http://dx.doi.org/10.1017/s0424820100150472.
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Polycrystalline alumina compacts often contain amorphous films at grain boundaries and triple junctions as a result of the liquid-phase sintering process. An anorthite-based composition (CaAl2Si2O8) is typical of the glassy phases observed in these materials. With appropriate heat treatments the glass phase can be crystallized, which can influence the properties of the bulk material. Deposition of a thin film of glass on single-crystal α-Al2O3 is being used to study the influence of specific crystallographic orientations on the alumina-glass interface properties. Vapor-phase growth of glass on different orientations of α-Al2O3 has been accomplished previously and, through subsequent thermal treatments, the alumina was shown to facet preferentially when in contact with a glassy phase. In the present study, calcium-aluminosilicate glass films were grown on single-crystal α-Al2O3 at relatively low substrate temperatures (<950°C) by pulsed-laser deposition. These films were then heated in the electron microscope to determine the effect of α-Al2O3 crystallography on crystallization of calcium-aluminosilicate glasses.
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Niciu, H., Dorel Radu, C. Onose, A. Ioncea, Daniela Niciu, H. Stroescu et C. S. Onose. « The Permanently Bonded Glass Decor from Chemical Precursors ». Advanced Materials Research 39-40 (avril 2008) : 579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.579.
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Alkaline earth metal silicates as well as many polyvalent metals silicates can be obtained through aqueous solutions reactions between an alkaline silicate solution and the solutions of metal salts. The vitrifiation of the oxide compositions, established by the necessary molar ratios for the projected glass, is realised by calculating the concentration of chemical precursors, through their reaction directly on the substrate. The sodium silicate viscosity in aqueous solution and the viscosity of nitrogenated compounds or oxalates necessary in the silicates synthesis is compatible with the necessary viscosity for ink-jet cartridges. The necessary silicates forming reactions were studied directly on the deposition support, so that the functional characteristics of the multicompartment ink-jet cartridges were used. Compositions were realised, in which the colouring effect was obtained with ionic colorants. The vitrifiation and the quality of the obtained thin films were studied through Optical Microscopy and Scanning Electron Microscopy.
13
Galoisy, L., L. Cormier, S. Rossano, A. Ramos, G. Calas, P. Gaskell et M. Le Grand. « Cationic ordering in oxide glasses : the example of transition elements ». Mineralogical Magazine 64, no 3 (juin 2000) : 409–24. http://dx.doi.org/10.1180/002646100549472.
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AbstractStructural data have been obtained on the cation surroundings in multi-component silicate and borosilicate glasses using chemically selective spectroscopic and scattering methods, such as extended X-ray absorption and neutron scattering with isotope substitution (NSIS). Transition elements such as Ni or Ti may occur in unusual 5-coordinated sites which coexist with other coordination numbers, depending on glass composition. Distribution of cationic sites in the glassy structure is responsible for unusual spectroscopic properties, as shown by Fe2+ Mössbauer spectroscopy. The environment of cations such as Zn, Zr or Mo, has been determined by EXAFS and discussed using the bond valence theory, which predicts the way to charge compensate the oxygen neighbours and which indicates the linkage of cationic sites with the silicate framework. Cation-cation correlations are given by NSIS up to ∼8 Á, indicating an extensive Medium Range Ordering (MRO) with corner- and edge-linked cationic polyhedra, for Ti and Ni-bearing glasses, respectively. This heterogeneous cationic distribution in glasses is consistent with the presence of two-dimensional domains in which cation mixing may occur, as shown in a Ca-Ni metasilicate glass. Three-dimensional domains have also been found by Ni-K edge EXAFS in the case of low alkali borate glasses, with a local structure which mimics some aspects of crystalline NiO. The presence of ordered cationic domains, clearly illustrated by Reverse Monte Carlo simulations helps to rationalize the physical properties of multi-component silicate glasses.
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Chen, Xiaojing, Natalia Karpukhina, Delia S. Brauer et Robert G. Hill. « High chloride content calcium silicate glasses ». Physical Chemistry Chemical Physics 19, no 10 (2017) : 7078–85. http://dx.doi.org/10.1039/c6cp07905a.
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Chloride is known to volatilize from silicate glass melts and until now, only limited studies on oxychloride silicate glasses have been reported. In this paper we have synthesized silicate glasses that retain large amount of CaCl2.
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Cheng, Shangcong. « Structures of Sodium Silicate Glass ». Non-Metallic Material Science 3, no 2 (29 novembre 2021) : 39–45. http://dx.doi.org/10.30564/nmms.v3i2.4070.
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The structural model of sodium silicate glass plays a crucial role in understanding the properties and the nature of binary glass and other more complicated silicate glasses. This work proposes a structural model for sodium silicate glass based on the medium-range ordering structure of silica glass and the information found from the Na2O-SiO2 phase diagram. This new model is different from previous ones. First, the sodium silica glass is both structurally and chemically heterogeneous on the nanometer scale. Secondly, the sodium cation distribution is Na2O concentration-dependent. In order to reflect the structural change with Na2O concentration, it requires two different schematic graphs to present the glass structure. The model can be extended to other binary and multiple component silicate glasses and can be experimentally verified.
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Vedyakov, Ivan, Vladimir Vaskalov, Nikolai Maliavski et Mikhail Vedyakov. « Highly Efficient Glass Ceramic Thermal Insulation ». E3S Web of Conferences 263 (2021) : 01017. http://dx.doi.org/10.1051/e3sconf/202126301017.
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Alkali-silicate thermal insulation materials (foam silicates) belong to the group of mineral heat insulators. Their main disadvantage is insufficient water resistance, to increase which special water-strengthening additives are introduced into materials. The aim of this work was to obtain and study foam silicates in granular (FGCG) and slab (FGCS) forms using a new production technology characterized by a simple one-stage technological scheme. Natural or technogenic amorphous silica, glassy sodium silicate (with the addition of carbonate or hydroxide) and a carbon-containing foaming agent, were used as the raw materials. Some part of the silica component was included in the binder solution, which made it possible to increase the silicate modulus in the final product to 5-10. This factor together with rather high Al2O3 concentration in the silica raw, made it possible to obtain foamed materials of very high water resistance. Another feature of the applied technology was a high foaming temperature (750–900°C). This factor makes a significant contribution to improving the water resistance of foam silicates, and significantly reducing their thermal conductivity and water absorption. As a result, FGCG was obtained with a bulk density of 170-440 kg/m3 (for FGCS – 300-400 kg/m3), a compressive strength in a cylinder of 0.5-6.3 MPa, a thermal conductivity of 0.046-0.084 W/(m·K) and a water absorption of 7.8-13.5% by volume. Mass loss of the specimens in boiling water was 0.12-0.33%, which puts obtained foamed materials on a par with most waterproof foam silicates being produced today.
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Mitchell, Roger H. « Coexisting glasses occurring as inclusions in leucite from lamproites : examples of silicate liquid immiscibility in ultrapotassic magmas ». Mineralogical Magazine 55, no 379 (juin 1991) : 197–202. http://dx.doi.org/10.1180/minmag.1991.055.379.07.
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AbstractInclusions occurring in leucites from the Oscar and Zirkel Mesa leucite lamproites consist of high (>10 wt.%) and low (<4 wt.%) K2O discrete glass phases which are interpreted to have resulted from silicate liquid immiscibility. Both glasses are quartz-normative and rich in Ti, Fe, Mg, Ca and Ba and poor in Al. The high-K glass is strongly peralkaline. Neither of the glasses have compositions representative of any known lamproites. These inclusions represent the first described examples of silicate-silicate immiscibility shown by glass in alkaline rocks.
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Ruengsri, Suwimon. « Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices ». Science and Technology of Nuclear Installations 2014 (2014) : 1–5. http://dx.doi.org/10.1155/2014/218041.
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Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of the glass matrices. The silicate and phosphate glass systems are more appropriate choices as lead-based radiation shielding glass than the borate glass system. Moreover, comparison of results has shown that the glasses possess better shielding properties than standard shielding concretes, suggesting a smaller size requirement in addition to transparency in the visible region.
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Morard, Guillaume, Jean-Alexis Hernandez, Marco Guarguaglini, Riccardo Bolis, Alessandra Benuzzi-Mounaix, Tommaso Vinci, Guillaume Fiquet et al. « In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures ». Proceedings of the National Academy of Sciences 117, no 22 (15 mai 2020) : 11981–86. http://dx.doi.org/10.1073/pnas.1920470117.
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Properties of liquid silicates under high-pressure and high-temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core–mantle boundary. Here we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6,000 K along the MgSiO3glass Hugoniot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth’s core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures.
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Galeener, F. L. « A Focus on Glasses ». MRS Bulletin 12, no 5 (août 1987) : 17–19. http://dx.doi.org/10.1557/s0883769400067452.
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The following series of articles focuses attention on five important groups of glassy materials: silica, oxynitride, phosphate, chalcogenide, and halide glasses. Each author has made a concerted effort to indicate the nature of the scientific questions and technological applications which make his individual area of materials research both exciting and timely. Nevertheless, these five articles can cover only a few of the identifiable areas of glass science and technology which are active and find new importance today. A broader picture can be obtained by perusal of the general texts listed in References 1-13.Glasses are usually defined as a sub-class of amorphous materials which exhibit a glass transition and are formable by quenching from the melt. They include numerous oxides, chalcogenides, halides, polymers, organic glasses, and amorphous metals. We have chosen to discuss only the first three of these groupings, which largely comprise the traditional inorganic glasses. The oxide glasses are only partly covered by our first three articles; completeness would require descriptions of activities involving alkalisilicate glasses, alumino-silicates, boro-silicates, boro-phosphates, and more.Amorphous materials which are not viewed as glasses include tetrahedral amorphous semiconductors like a-Ge and a-Si, either pure or containing alloy levels of H, F, Cl, B, P, or other elements.
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Saakyan, Emma, Artavazd Arzumanyan et Gagik Galstyan. « Chemical technology of cellular glass production ». E3S Web of Conferences 97 (2019) : 02012. http://dx.doi.org/10.1051/e3sconf/20199702012.
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Cellular glass by its composition, structure and technical parameters is a high-performance multifunctional material, and its use in construction and engineering is extremely important. The problem of developing cellular glass power consumption technology on the base of natural amorphous aluminosilicates and silica rocks in a single technological process, combining the synthesis of a given glass composition and the formation of its cellular structure is solved by introduction of a nanodispersed modifier into the rock and by the mechanical activation of the charge, creating an impact possibility in the system at the atomic-molecular level. With the involvement of a complex modern theoretical and experimental methods, the processes of glass wool rock modifyed sintering and expanding were investigated, which served as a base for creating the cellular glass technology in the form of products and granules. The study of the secondary glass synthesis dynamics during sintering of volcanic glasses with sodium hydroxide solution showed that the hydrated amorphous neoplasms of sodium silicates synthesized at low temperatures and silica aluminosilicates with temperature rise gradually enriched with silica and formed hydrated secondary glasses, the dehydration of which expanded the mass upon reaching the pyroplastic state. Power consumption technologies of the new type cellular glasses based on the volcanic glass-wool and other amorphous silicate rocks, which allow to combine the processes of synthesis of low-melting glass and its expansion by sintering are challenging for the production and for application in construction and engineering.
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Liang, Wen, Christian Rüssel, Delbert E. Day et Günter Völksch. « Bioactive comparison of a borate, phosphate and silicate glass ». Journal of Materials Research 21, no 1 (1 janvier 2006) : 125–31. http://dx.doi.org/10.1557/jmr.2006.0025.
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A borate glass, phosphate glass, and silicate glass were converted to hydroxyapatite (HA) by soaking the substrates in a solution of K2HPO4 with a pH value of 9.0 at 37 °C. The weight loss of the substrates was studied as a function of time. Unlike the silicate glasses, the reaction processes of the borate glasses and phosphate glasses were bulk dissolution. X-ray diffraction and scanning electron microscopy revealed an initially amorphous product that subsequently crystallized to HA. The data suggest good bioactive characteristics for the borate and phosphate glass and the potential use of them as a favorable template for bone-tissue formation.
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Suetsugu, Tatsuya, Takashi Wakasugi et Kohei Kadono. « Effect of glass composition on silver-incorporation into aluminoborosilicate glasses through a staining process ». Journal of Materials Research 25, no 4 (avril 2010) : 701–7. http://dx.doi.org/10.1557/jmr.2010.0086.
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To fabricate graded-index optical elements by silver staining, we investigated the behavior of ion incorporation in aluminoborosilicate glasses, in which the contents of Al2O3 and Na2O were the same (in mol%). The amount of silver incorporated into the aluminoborosilicate glasses by the staining at 320 °C for 12 h was 5 to 10 times larger than that incorporated into the soda-lime silicate and borosilicate glasses. The diffusion depth of the incorporated silver ions was approximately 80 μm, which was also much deeper than that of the soda-lime silicate and borosilicate glasses. The coloration of the glasses was suppressed, particularly for the glass with the low content of Na2O. The concentration of the incorporated silver ions at the glass surface was 2 × 1021 atom/cm3 for the 37.5SiO2·25Al2O3·25Na2O·12.5B2O3 glass, corresponding to the replacement of sodium ions (20%). The refractive indices near the stained surfaces increased by 0.04 to 0.06. These values were comparable with those of the soda-lime silicate and borosilicate glasses.
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Lipatiev, A. S., G. Yu Shakhgildyan, M. P. Vetchinnikov, S. V. Lotarev et V. N. Sigaev. « Laser-assisted formation of luminescent domains in metal- or semiconductor-doped silicate and phosphate glasses ». Journal of Physics : Conference Series 2015, no 1 (1 novembre 2021) : 012163. http://dx.doi.org/10.1088/1742-6596/2015/1/012163.
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Abstract In this study, silicate and phosphate glasses doped with Ag or CdS were exposed to femtosecond laser pulses and photoluminescence properties of the laser-written domains were investigated. Laser writing in phosphate glass doped with CdS was found to induce very weak photoluminescence, while laser-written domains in silicate glass had a comparatively high photoluminescence intensity, that was assigned to the formation of the sulphur vacancies in the CdS nanocrystals precipitated under the ultrafast laser pulses. Observed photoluminescence bands in Ag-containing glasses we assigned to the formation of different silver nanospecies which provide photoluminescence bands with the maxima at 685 and 600 nm in Ag-doped silicate and phosphate glasses, respectively.
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Hampshire, Stuart, Amir R. Hanifi, Annaik Genson et Michael J. Pomeroy. « Ca-SiAlON Glasses : Effects of Fluorine on Glass Formation and Properties ». Key Engineering Materials 352 (août 2007) : 165–72. http://dx.doi.org/10.4028/www.scientific.net/kem.352.165.
Texte intégralRésumé :
Oxynitride glasses are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, resulting in increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium alumino-silicate glasses containing fluorine are known to have useful characteristics as potential bioactive materials. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful bioglasses with enhanced mechanical stability. This paper gives a review of oxynitride glasses and reports glass formation and evaluation of glass properties in the Ca-Si-Al-O-N-F system. Within the previously defined glass forming region in the Ca-Si-Al-O-N system, homogeneous, dense glasses are formed. However, addition of fluorine affects glass formation and reactivity of the glass melts and can lead to fluorine loss as SiF4, but also nitrogen loss, and cause bubble formation. At high fluorine and high Ca contents under conditions when Ca- F bonding is favoured, CaF2 crystals precipitate in the glass. It was found that fluorine expands the glass forming region of Ca-Sialon system and facilitates the solution of nitrogen into the melt.
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Wójcik, N. A., S. Ali, A. Mielewczyk-Gryń et B. Jonson. « Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses ». Journal of Materials Science 56, no 12 (25 janvier 2021) : 7613–25. http://dx.doi.org/10.1007/s10853-021-05781-w.
Texte intégralRésumé :
AbstractNiobium doped biosolubility glasses in the Na–Ca–(Mg)–P–Si–O system were prepared by using an untypical two-step synthesis route. The parent glass was melted in air atmosphere at 1350 °C followed by re-melting the glass in Nb crucible with the addition of metallic Mg/Ca powder in the nitrogen atmosphere. The second melting step was carried out at 1450–1650 °C, using an induction furnace. The topography and structure of the obtained glasses were characterized by confocal microscopy, X-ray powder diffraction and infrared spectroscopic techniques. The chemical compositions were examined by energy-dispersive X-ray spectroscopy (EDS). The glasses were found to be of grayish color, X-ray amorphous and having network connectivity between ~ 2.5 and 2.7. The network connectivity of re-melted glasses was lower than the one of the parent glass. The glass structure consists of a highly disrupted silicate network of predominantly Q2 groups as well as isolated orthophosphate tetrahedra. The parent glass contains nanocrystallites consisted of apatitic PO43− groups. The re-melted glasses contain non-apatitic or amorphous calcium phosphates. The obtained glass transition temperatures range from 530 to 568 °C and exhibit higher values for glassed doped with Ca metal. These glasses have improved thermal stability as compared to reference bioglasses. The biosolubility test in phosphate buffered saline solution (PBS) confirms that the glasses have biosolubility properties and HAp formation on the surfaces was observed.
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Hamada, Yuya, Teppei Murota, Masahiro Shimizu, Yasuhiko Shimotsuma et Kiyotaka Miura. « Volume relaxation of soda-lime silicate glasses below glass transition temperature ». AIP Advances 13, no 2 (1 février 2023) : 025353. http://dx.doi.org/10.1063/5.0131705.
Texte intégralRésumé :
Structural relaxation is a widely known phenomenon that occurs in glassy systems, which still attracts strong industrial and research interest. Although the volume change associated with structural relaxation is well described by the Kohlrausch–Williams–Watts function, its origin, particularly from a glass structural viewpoint, is not clearly defined. To understand the behavior of structural relaxation, in this study, we performed volume relaxation evaluations, Raman spectroscopy assessments, and surface resistivity measurements before and after annealing at 50 K below the glass transition temperature Tg of soda-lime silicate glasses with the same Tg but different fragilities. The combined results indicated that the following changes in the glass structure occurred during the structural relaxation: (1) reorganization of the SiO2 network; (2) transfer of Na ions from the ion channel region into the SiO2 network region; and (3) segmentation of the ion channel region in the modified random network model.
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Fanara, Sara, Harald Behrens et Regina Kappes. « Ionic Conductivity of Hydrous Silicate Glasses ». Advances in Science and Technology 46 (octobre 2006) : 89–92. http://dx.doi.org/10.4028/www.scientific.net/ast.46.89.
Texte intégralRésumé :
Hydrous silicate glasses with different compositions (LiAlSi4O10, CaMgSi2O6, CaMgSi2O6 - CaAl2Si2O8 and (Ca,Ba,Sr)O – SiO2) containing up to 3 wt% H2O were synthesized in platinum capsules at high temperature and pressures from 100 to 500 MPa in an internally heated gas pressure vessel. The water content of the glasses was analyzed by Karl-Fischer titration. Using infrared microspectroscopy the homogeneity of water distribution in the samples was checked and concentrations of OH- groups and H2O molecules were estimated. Frequency-dependent ionic conductivity of the glasses was investigated using impedance spectroscopy. It is shown that the proton conductivity is usually orders of magnitude lower than the partial conductivity of alkalis in silicate glasses. Proton conductivity in hydrous barium silicate glass was found to be more than one order of magnitude higher than in an aluminosilicate glass, supporting that the concentration of non-bridging oxygen is crucial for proton conduction in glasses.
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Sava, Bogdan Alexandru, Adriana Diaconu, Luminita Daniela Ursu, Lucica Boroica, M. Elisa, Cristiana Eugenia Ana Grigorescu, Ileana Cristina Vasiliu et al. « Ecological Silicate Glasses ». Advanced Materials Research 39-40 (avril 2008) : 667–70. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.667.
Texte intégralRésumé :
The investigated ecological glasses with no toxic compounds, such as BaO, PbO, As2O3, As2O5, fluorine, CdS and CdSe in their composition are located in ternary and quaternary oxide systems: ZnO-SiO2-TiO2 and SiO2-R'2O-R''O-R'''O2, where R' is Na or K, R'' is Ca or Mg and R''' is Zr or Ti. The first system contains P2O5, ZnO and TiO2 in order to obtain opal glasses, without fluorine compounds. The second system replaces the barium oxide and lead oxide with potassium, magnesium, zirconium and titanium oxides, for materials like lead free crystals. The raw materials can be replaced by silicate or borosilicate glass waste. The advantages of borosilicate glass waste are: bringing valuable components into recipes (B2O3, CaO, Al2O3), saving raw materials and energy, creating an ecological environment The characteristic temperatures (vitreous transition point, low and high annealing points, softening point) and the thermal expansion coefficient of the glass are presented. The FTIR and Raman spectroscopy provided structural data, such as characteristic vibration maxima for silicon and titanium oxide, and revealed the role of zinc oxide in the vitreous network. The refraction index and UV-VIS transmission are discussed.
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Iliushchenko, V., L. Kalina, P. Hruby, V. Bilek Jr, J. Fladr, P. Bily et J. Bojanovsky. « The treatment of cementitious surface by selected silicate sealers ». Journal of Physics : Conference Series 2341, no 1 (1 septembre 2022) : 012003. http://dx.doi.org/10.1088/1742-6596/2341/1/012003.
Texte intégralRésumé :
Over the past decades, the efficiency of the silicate-based surface treatment agents, in other words, sealers, in concrete systems has been widely investigated. The surface treatment technology protects the cementitious systems against the penetration of undesirable substances. Nevertheless, understanding of the several aspects concerning silicate-based sealers is not entirely clear. This paper studies the action mechanism of selected silicates such as potassium, sodium, lithium water glasses, and colloidal silica. The effectiveness of used sealers in terms of water absorption reduction, the ability of silicates to heal pores, and the influence on the microstructure of the cement substrate were studied. Instrumental methods such as rheology, mercury intrusion porosimetry, or scanning electron microscopy were used to achieve satisfactory results. Nuances between the unique film-forming sealers were found. Colloidal silica showed a low sealing effect compared to alkali silicates.
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Meechoowas, Ekarat, Benjamon Petchareanmongkol, Usanee Pantulap et Kanit Tapasa. « The Effect of Lithium on Crystallization and Microstructure of Glass-Ceramics in Soda-Lime Silicate System ». Solid State Phenomena 283 (septembre 2018) : 160–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.283.160.
Texte intégralRésumé :
This study investigated the crystallization of soda-lime silicate (NCS) system by re-melting soda-lime silicate glass cullet with Al2O3 CaCO3 and Li2O. The Li2O was added as a nucleating agent. The effect of the nucleating agent on crystallization was investigated in order to study the possibility for use as a parent glass for glass-ceramics. Soda-lime silicate cullet was the main raw material and its chemical composition by weight was 68% SiO2 2% Al2O3 9% Na2O 9% K2O 3.5% CaO 2.5% MgO 1.2% TiO2 3% SrO and 2% ZnO. Glass batches with composition (%wt) of (65-x) Cullet:13Al2O3:22CaCO3:x(Li2O) (x = 0, 1, 2, 4, 6 and 8) were melted at 1500°C for 3 hours and annealed at 600°C. All glasses added with Li2O were clear except x = 8. The crystallization was investigated by Differential Scanning Colorimetry technique (DSC). The results exhibited the exothermic peak of crystallization (TpI and TpII). The glasses with added Li2O exhibited decreasing crystallization temperature with increasing Li content. The glasses were heated at temperatures around the crystallization temperature (700, 750 and 800°C). After heat treatment, the crystalline phase in the glasses was determined by X-ray diffraction technique (XRD). The microstructure was investigated by optical microscope and Scanning Electron Microscope (SEM). The phases of Nepheline (Na,K)AlSiO4 and Wollastonite (CaSiO3) were found. The crystallization depended on the heat treatment temperature. The thermal expansion of the glasses was determined by the dilatometric method to indicate the characteristics of the glass-ceramics. In conclusion, Li2O had a strong effect on the crystallization in soda-lime silicate system. The result could be applied for the production of glass-ceramics from soda-lime cullet.
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Meechoowas, Ekarat, Surisa Suriyoporn, Usanee Pantulap et Kanit Tapasa. « The Effect of Zirconium Oxide on Properties and Crystallization of Soda-Lime Silicate Glass ». Key Engineering Materials 751 (août 2017) : 374–78. http://dx.doi.org/10.4028/www.scientific.net/kem.751.374.
Texte intégralRésumé :
In this study, the properties and crystallization of re-melted soda-lime silicate glass cullet added with Al2O3, CaCO3 and ZrO2 were investigated in order to study the potential usage as a parent glass for glass-ceramics. Al2O3, CaCO3 and ZrO2 were added into the 71SiO2-10Na2O-6K2O-5CaO-4MgO-2SrO-ZrO2-Al2O3 glass cullet to increase the crystallization of the glass. The glass batches (%wt) of (65-x) Cullet:13Al2O3:22CaCO3:xZrO2 (x = 0, 1, 2, 4, 6 and 8) were melted at 1500°C for 3 hours. The crystallization was investigated by Differential Scanning Colorimetry technique (DSC) and it was found that the glasses with 6 and 8 %wt of ZrO2 crystallized rapidly. It means that ZrO2 acted as the nucleating agent in this glass system. The major crystallines determined by X-ray diffraction technique (XRD) were silica (SiO2), wollastonite (CaSiO3) potassium silicate (K6Si3O9) and zirconium oxide (ZrO2). The thermal expansion of glasses determined by dilatometric method indicated the characteristic of glass-ceramics and the effect of ZrO2 on the thermal properties of glass. In conclusion, modifying the composition of soda-lime silicate cullet with Al2O3 CaCO3 and ZrO2 had potential to produce glass-ceramics.
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Brow, Richard K., Todd M. Alam, David R. Tallant et R. James Kirkpatrick. « Spectroscopic Studies on the Structures of Phosphate Sealing Glasses ». MRS Bulletin 23, no 11 (novembre 1998) : 63–67. http://dx.doi.org/10.1557/s088376940003102x.
Texte intégralRésumé :
Phosphate glasses generally have lower glass-transition temperatures and greater thermal-expansion coefficients than silicate and borate glasses, and so are candidate materials for specialty glass-metal sealing applications. Phosphate glasses also have desirable optical properties (rare-earth stimulated-emission cross sections, low thermo-optical coefficients, ultraviolet transparency, etc.) and so are used as laser glasses. Recent developments of novel compositions for biomedical applications and as fast-ion conductors have also revived interest in the study of phosphate glass structures.The structure/property relationships in simple phosphate glasses have not received nearly the attention paid to silicate and borate-based systems. This is partially due to the difficulty in preparing anhydrous compositions with more than 50-mol% P2O5. Ultraphosphate compositions (where the [O]/[P] ratio is less than 3) are highly reactive to ambient water. In addition because P2O5 sublimes at about 300°C, ultraphosphate glasses have not been studied to the extent that metaphosphate ([O]/[P] = 3) and polyphosphate ([O]/[P] > 3) compositions have.
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Hisano, Naoki, Tatsuya Sakamaki, Tomonori Ohashi, Ken-ichi Funakoshi, Yuji Higo, Yuki Shibazaki et Akio Suzuki. « Elastic properties and structures of pyrope glass under high pressures ». American Mineralogist 106, no 1 (1 janvier 2021) : 7–14. http://dx.doi.org/10.2138/am-2020-7410.
Texte intégralRésumé :
Abstract X-ray diffraction analysis and ultrasonic measurements of a glass with the pyrope composition were conducted to determine its structural and elastic properties at pressures from 1 atm to 12.9 GPa. Our results indicate that its structural evolution is closely related to changes in the compression wave velocity (VP), shear wave velocity (VS), and Poisson ratio. We observed three modes of pyrope glass compression. Moderate shrinkage in the intermediate-range ordered structure occurred at pressures below 6 GPa. Significant shrinkage in the intermediate-range ordering was observed at pressures between 6 and 9 GPa. We observed changes in the short-range ordered structure at pressures above 9 GPa, which were associated with an increase in the coordination number of tetrahedral cations. The absolute values of VP and VS in pyrope glass are similar to those in magnesium-bearing silicate glasses with enstatite and diopside compositions. However, the velocities are higher than those observed in sodium aluminum silicate glasses with jadeite and albite compositions. This indicates that the velocities are governed by the initial density of a glass, which is determined by its chemical composition. In terms of pressure, the velocity minimum in pyrope glass occurs at ~5 GPa, which is similar to the velocity minima in fully polymerized glasses, such as jadeite and albite. The degree of polymerization in pyrope glass is intermediate, and it has a relatively polymerized network. A drastic increase in velocity was observed when the pyrope glass was subjected to pressures above 7–8 GPa, and the velocity exceeded that observed in silicate glasses. Densification phenomenon, such as an increase in the Al coordination number, was efficiently promoted. This was because the cationic field strength of Mg2+ exceeds those of typical non-network forming cations. Magnesium cations may have an important role in controlling the behavior of silicate glass, and partially melted mantle becomes enriched with Mg under pressure. Studying Mg-bearing aluminosilicate glasses can thus help us to better understand the behavior of magma deep in the interior of the Earth.
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Bondar, Dali, et Raffaele Vinai. « Chemical and Microstructural Properties of Fly Ash and Fly Ash/Slag Activated by Waste Glass-Derived Sodium Silicate ». Crystals 12, no 7 (27 juin 2022) : 913. http://dx.doi.org/10.3390/cryst12070913.
Texte intégralRésumé :
Sodium silicate is commonly used for activating alumina silicates to produce alkali-activated binders that can compete with conventional Portland cement in concrete. However, the cost and emissions related to activators can hinder the use of alkali-activated materials in the industry. The novel, waste-based activators have been developed in the last years, using Si-rich waste streams. Processing waste glass cullet not only reduces the glass landfill disposal but also allows the production of sodium silicate for alkali activation. In this article, the chemical and microstructural properties of neat fly ash and blended 60 fly ash/40 slag pastes activated by sodium silicate produced from glass cullet were studied and compared to equivalent ones activated by commercially available sodium silicate and sodium hydroxide solutions. Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) were used to determine the microstructure and composition of the gel phase. Findings have confirmed that pastes activated by the processed waste glass showed chemical and microstructural properties comparable to pastes produced with commercially available activators.
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Hanifi, Amir R., Annaik Genson, Michael J. Pomeroy et Stuart Hampshire. « An Introduction to the Glass Formation and Properties of Ca-Si-Al-O-N-F Glasses ». Materials Science Forum 554 (août 2007) : 17–23. http://dx.doi.org/10.4028/www.scientific.net/msf.554.17.
Texte intégralRésumé :
Ca-Sialon glasses have been known for some time [1] and they are effectively calciumalumino- silicate glasses containing nitrogen which improves their mechanical properties. Calciumalumino- silicate glasses containing fluorine are known to have useful characteristics as potential bioactive materials [2]. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful bioglasses with enhanced mechanical stability.Addition of fluorine to oxynitride glasses was not reported previously and this paper gives the first report of the glass forming regions (and evaluation of some properties) in the Ca-Si-Al-O-N-F system. Within the previously defined [1] glass forming region in the Ca-Si-Al-O-N system, homogeneous, dense glasses are formed. Addition of fluorine extends the glass forming region but also increases the reactivity of the glass melts. One major problem is fluorine loss as SiF4, but also loss of nitrogen, which affects the final composition and results in porous samples. To suppress the fluorine loss and CaF2 precipitation, consideration of the ratio of cations to fluorine and the coordination number of Al atoms is important. Discussion of the role of cations in these oxyfluoronitride glasses is presented.
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Shakhgildyan, Georgiy. « Influence of Plasmonic Gold Nanoparticles on the Optical Properties of Oxide Glasses Doped with Rare-Earth Ions ». Key Engineering Materials 907 (21 janvier 2022) : 38–43. http://dx.doi.org/10.4028/www.scientific.net/kem.907.38.
Texte intégralRésumé :
We report on the thermally-induced precipitation of gold plasmonic nanoparticles in phosphate and silicate glasses, doped with Eu3+ and Er3+ ions. We studied the structure and optical properties of glasses under the heat treatment below and above glass transition temperature. The heat treatment of the glass at temperatures above transition is shown to facilitate the formation of plasmonic gold nanoparticles and decrease near-infrared luminescence intensity of the ions. The formation of pre-plasmonic gold nanoparticles under the low-temperature heat-treatment leads to the increase of luminescence intensity through the energy transfer process. We showed that nanophase separation in silicate glasses allows precise tuning of localized surface plasmon resonance spectral position of gold nanoparticles and paves the way for the development of new glass-based materials for photonics applications.
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Liu, Xiao Qing, et Jun Lin Xie. « OH-related Infrared Absorption Spectra in Silicate Glasses ». Advanced Materials Research 295-297 (juillet 2011) : 1108–12. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1108.
Texte intégralRésumé :
To discover the water structure in glass, two silicate glasses were synthesized under different melting atmospheric conditions. Fourier transform infrared spectrometric analyzer was used to study the OH contents and the infrared spectra bands in 1300-4000cm-1of the glasses. The research shows that water contents of glass samples melted under air atmosphere and oxyfuel firing atmosphere are 0.0323wt% and 0.0512wt% respectively. The infrared absorptions in 1300-4000cm-1band are dominantly related with water dissolved in glass melt. Water existing in glass is mainly in the form of Si-OH, in addition with some free OH connected with metal cations. The IR absorption of ferrous ion in glass is near 3430cm-1, while the IR absorption near 2500 cm-1does not belong to the vibration of KOH.
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Chimalawong, Parnuwat, Jakrapong Kaewkhao, Keerati Kirdsiri et Pichet Limsuwan. « A Study of the Physical and Optical Properties of Ho3+ in Soda-Lime-Silicate Glass Systems ». Advanced Materials Research 770 (septembre 2013) : 140–44. http://dx.doi.org/10.4028/www.scientific.net/amr.770.140.
Texte intégralRésumé :
Soda-lime-silicate glasses in the compositions of (65-x)SiO2-25Na2O-10CaO-xHo2O3 (where x = 0.0, 0.50, 1.00, 1.50, 2.00 and 2.50 mol % ) were prepared by melt-quenching technique and characterized. The results show that, the absorption spectra of Ho3+ doped in soda-lime-silicate glass correspond with several bands, which are assigned from the ground state, 5I8 to 3H6 (360 nm), 5G4 (380 nm), 5G5 (417 nm), 5G6 (453 nm), 5F3 (479 nm), 5F4 (538 nm), 5F5 (639 nm), and 5I5 (880 nm). The refractive index and density of glasses were increase with increasing of Ho2O3 concentration. The color of glass samples is light amber with doped Ho2O3 in glass matrix.
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Ravishankar, N., et C. Barry Carter. « Silicate Glass and Evaporation from Sapphire Surfaces ». Microscopy and Microanalysis 6, S2 (août 2000) : 388–89. http://dx.doi.org/10.1017/s1431927600034437.
Texte intégralRésumé :
Ceramic materials are processed at high temperatures where different mechanisms of mass transport are operative. The liquid-phase sintering (LPS) process involves the formation of a silicate liquid at the sintering temperature. In this case, mass transport takes place at the solidliquid, solid-vapor and liquid-solid interfaces. The mechanism and kinetics of these processes controls the microstructure. The silicate phase, which is usually the sintering additive, may influence the evaporation from and of the ceramic. The importance of the evaporation process has been clearly brought out in previous studies on the dewetting of silicates on a ceramic substrate. The present study considers the influence of a silicate phase (celsian) on evaporation from a ceramic (sapphire) substrate.Pulsed-laser deposition (PLD) has been used to deposit thin films (∼100 nm thick) of celsian (BaAl2Si2O8) on sapphire single-crystals of basal orientation. In the present study, the film/substrate assembly has been annealed at high temperatures (1750°C to 1850°C) in a vacuum furnace.
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Feike, M., K. Meise-Gresch, Qi Chen et G. H. Frischat. « NMR and FTIR Characterization of Sol-Gel Derived Ternary Oxide Glasses in the System BaO–TIO2–SiO2 ». Zeitschrift für Naturforschung A 50, no 9 (1 septembre 1995) : 837–44. http://dx.doi.org/10.1515/zna-1995-0908.
Texte intégralRésumé :
Abstract The annealing history of glasses in the system (20-40) BaO-40TiO2(40-20)SiO2 has been monitored by 29Si MAS NMR and FTIR spectroscopy from the dried gel to the final glassy state. Assignment of chemical shifts to specific building units has been facilitated by comparative studies of the limiting less complex binary silicate systems. From the NMR spectra at various compositions appreciable condensation to a three-dimensional network is inferred already at low drying temperatures. Processes like the pyrolysis of acetate rests of the starting materials and modification of the silicate structure due to Ba2+ cations have been mirrored in the spectra of both methods for samples annealed at intermediate temperatures. The microstructure of the final gel glass of the ternary system has been determined spectroscopically to consist of silicate and titanate species typical of crystalline fresnoite, whereas remaining amounts of TiO2 and SiO2 develop a separate network each. Only small amounts of Si-O-Ti linkages have been recognized in the vibrational absorptions; they vanish at higher annealing stages.
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Loehman, Ronald E. « Oxynitride Glasses ». MRS Bulletin 12, no 5 (août 1987) : 26–31. http://dx.doi.org/10.1557/s0883769400067476.
Texte intégralRésumé :
Research on oxynitride glasses has expanded considerably since the first systematic compositional investigations were begun some ten years ago. This review will briefly introduce that work with an emphasis on more recent developments. Also included is some discussion of the applications of oxynitride glasses in both bulk and thin film form. The literature review is selective, however, and the recently developed phosphorus oxynitride glasses are only briefly mentioned. For more detailed information on earlier work on silicon oxynitride glasses see the reviews by Jack and Loehman. For discussions of phosphorus oxynitride glasses see Marchand, Peng and Day, and Rajaram and Day.The development of bulk oxynitride glasses has been closely associated with research on Si3N4 and other nitrogen-containing ceramics. The initial discovery that large amounts of nitrogen can be incorporated in silicate glasses originated with analyses of glassy grain boundary phases in Si3N4 that was hot-pressed or sintered with different additives to promote liquid phase formation at the processing temperature. (Some applications of oxynitride glasses take advantage of that close connection to Si3N4. See Applications of Oxynitride Glasses below.) Later, systematic study of the bulk oxynitride glasses showed that nitrogen incorporation increases density, hardness, glass transition temperature and fracture toughness, and, to a certain extent, decreases the thermal expansion coefficient. Nitrogen additions also tend to lower glass solubility in aqueous solutions.
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Nishida, Tetsuaki. « Verification of the ‘‘Tg-Δ Rule’’ in Potassium Silicate and Sodium Tungstate Glasses ». Zeitschrift für Naturforschung A 51, no 5-6 (1 juin 1996) : 620–26. http://dx.doi.org/10.1515/zna-1996-5-641.
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Abstract A linear relationship exists in oxide glasses between glass transition temperature (Tg) and quadrupole splitting (Δ) of Fe3+ . DTA and Mössbauer measurements of silicate and tungstate glasses yielded large slopes of 680 and 260 °C/(mm s-1) from the slope of the straight lines when Fe3+ occupied, as network former (NWF), distorted tetrahedral Si4+ and distorted octahedral W6+ sites, respectively. This linear relationship, named a ‘‘Tg - Δ rule’’, suggests that Tg is in proportion to the distortion of NWF-oxygen polyhedra and a higher activation energy is required for the fragments of glass to have a cooperative movement in the supercooled liquid state. The ‘‘Tg - Δ rule’’ was also valid in the case of potassium silicate glasses heat treated at the temperature close to Tg, indicating a distortion of SiO4 and FeO4 tetrahedra. Substitution of Fe3+ for individual NWF in silicate and tungstate glasses was confirmed from the Fourier transform infrared (FT-IR) spectra because only the absorption bands due to Si and W were respectively observed without the bands due to Fe.
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Salman, Saad, Samia Salama et Ebrahim Mahdy. « Contribution of di- and trivalent oxides to crystal phase formations and properties of yttrium aluminosilicate glass-ceramics ». Processing and Application of Ceramics 9, no 3 (2015) : 139–49. http://dx.doi.org/10.2298/pac1503139s.
Texte intégralRésumé :
The crystallization behaviour, phase composition, microhardness and chemical durability of some silicate glasses and glass-ceramics based on LiAlSi2O6-YAlSiO5 system were investigated. The effects of partial replacements of LiAlSi2O6 mostly with LiFeSi2O6 and complete replacement of YAlSiO5 with CaMgSi2O6 were considered. In some cases small amount of Cr2O3 was introduced as nucleating agent or Fe2O3 was partially replaced with chromium or indium oxides. The main crystalline phases formed after controlled heat-treatments of the glasses were yttrium-containing ?-spodumene solid solution (ss) - Li(Al,Y)Si2O6, together with varieties of pyroxene-ss including lithium iron pyroxene-ss - LiFeSi2O6-CaMgSi2O6, augite - Ca(Mg,Fe)Si2O6, chromoaugitess, Li-aegirine - LiFeSi2O6, diopside - CaMgSi2O6 and lithium indium silicate - LiInSi2O6 phases. The Vickers? microhardness values of the studied glasses (ranged from 4610 to 6185MPa) were greatly affected by the modifications of the glass compositions. On the other hand, the glass-ceramics? microhardness (7245- 8175MPa) was markedly improved depending on the microstructure and the nature of crystalline phases formed. The glass-ceramics have chemical stability better than those for the corresponding glasses.
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Palomar, Teresa, Pedro Redol, Isabel Cruz Almeida, Eduardo Pereira da Silva et Marcia Vilarigues. « The Influence of Environment in the Alteration of the Stained-Glass Windows in Portuguese Monuments ». Heritage 1, no 2 (19 novembre 2018) : 365–76. http://dx.doi.org/10.3390/heritage1020025.
Texte intégralRésumé :
This work presents the results of the exposure of soda-lime, potash-lime and mixed-alkali silicate glasses during ten and twenty months in different Portuguese monuments with historical stained-glass windows to characterize the influence of local environmental conditions. The glass samples were exposed in the Monastery of Batalha (Batalha), the Monastery of Jerónimos (Lisbon), and the Cathedral of Évora (Évora). A set of analytical techniques to assess the physicochemical effects were used, including optical microscopy and Fourier transform infrared spectroscopy. All the samples presented crystalline deposits on their surface; however, their quantity and nature depended on the atmospheric conditions during the days before the collection. Potash-lime silicate glass was the most altered glass in comparison with soda-lime and mixed-alkali silicate glasses. The samples from the Cathedral of Évora showed a high content of dust and salts on their surface but without severe chemical pathologies; however, those samples exposed in the Monastery of Jerónimos and the Monastery of Batalha presented alteration layers due to a high humidity environment.
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Loganina, Valentina I., et Erkebulan B. Mazhitov. « Regularities of formation of adhesive contact “sol-silicate paint - substrate” ». Vestnik MGSU, no 1 (janvier 2019) : 94–101. http://dx.doi.org/10.22227/1997-0935.2019.1.94-101.
Texte intégralRésumé :
Introduction. The use as a binder in the manufacture of silicate paints polysilicate solutions obtained by mixing liquid glass and silica sol is considered. To regulate the rheological properties of the paint, improve the filling and prevent the pigment part from sagging, it has been proposed to introduce glycerin into the binder composition. The results of studying the interfacial interaction between the paint and the substrate are given. Materials and methods. In developing the formulation of silicate paints based on polysilicate solutions, MK-2 microcalcite, marshalite, diatomite and talc of MT-GSM grade were used as a filler, and titanium dioxide as a pigment. Polysilicate solutions were obtained by reacting stabilized solutions of colloidal silica (sols) with aqueous solutions of alkali silicates (liquid glasses). Nanosil 20 and Nanosil 30 silicic acid sol were used, produced by the Promsteklocentr PC. Used potassium liquid glass with module M = 3.29. A thermodynamic method was used to assess the interfacial interaction. Results. Shown that the introduction of glycerol into the formulation of a sol of silicate paint promotes a decrease in the interfacial surface tension and a better wetting of the surface of the mortar substrate. An increase in wetting coefficient is observed. Coatings based on sol silicate paints with the addition of glycerin are characterized by increased crack resistance. An increase in tensile strength, maximum tensile properties, and decrease in the elastic modulus of paint membranes based on the composition with glycerol has been established. The values of the free surface energy of the coating based on the sol of silicate paint and the ratio of the polar to the dispersion component of the free energy of the surface are given. Coatings based on sol of silicate paint with the addition of glycerin are characterized by a large value of the free energy of the surface. In the process of moistening a decrease in the free surface energy is observed due to a decrease in the dispersion component. Conclusions. Studies have shown that the introduction of an additive of glycerin in the formulation of a silicate paint sol contributes to an increase in the performance properties of coatings based on it.
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Ashkhotov, O. G., et I. B. Ashkhotova. « INVESTIGATION OF THE INTERACTION OF LEAD-SILICATE GLASSES WITH BARIUM HYDROXIDE ». Steklo i Keramika, no 2 (2022) : 8–11. http://dx.doi.org/10.14489/glc.2022.02.pp.008-011.
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The effect of alkaline treatment on the destruction process and some surface characteristics of mechanically processed glass discs of lead-silicate glasses C87-2 and C78-4 has been studied. It is shown that the interaction of these glasses with barium hydroxide leads to the removal of silicic acid from the gel surface, which in turn improves the water wettability and optical transparency of the glasses. It is proposed in the production technology of electric vacuum devices, where lead-silicate glasses are used, to use washing with barite water for rapid coagulation of silica gel, which eliminates the appearance of foreign particles on the surface of the glasses.
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Tang, Danna, Yushen Wang, Zheng Li, Yan Li et Liang Hao. « Coupling additive manufacturing and low-temperature sintering : a fast processing route of silicate glassy matrix ». Rapid Prototyping Journal 28, no 4 (18 octobre 2021) : 676–85. http://dx.doi.org/10.1108/rpj-07-2020-0173.
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Purpose The low-temperature sintering of silica glass combined with additive manufacturing (AM) technology has brought a revolutionary change in glass manufacturing. This study aims to carry out in an attempt to achieve precious manufacturing of silicate glassy matrix through the method of slurry extrusion. Design/methodology/approach A low-cost slurry extrusion modelling technology is used to extrude silicate glassy matrix inks, composed of silicate glass powder with different amounts of additives. Extrudability of the inks, their printability window and the featuring curves of silicate glassy matrix are investigated. In addition, the properties of the low-temperature sintering green part as a functional part are explored and evaluated from morphology, hardness and colour. Findings The results showed that the particle size was mainly distributed from 1.4 µm to 5.3 µm, showing better slurry stability and print continuity. The parameters were set to 8 mm/s, 80% and 0.4 mm, respectively, to achieve better forming of three-dimensional (3D) samples. Besides, the organic binder removal step was concentrated on 200°C–300°C and 590°C–650°C was the fusion bonding temperature of the powder. The hardness values of 10 test samples ranged from 588 HL to 613 HL, which met the requirements of hard stones with super-strong mechanical strength. In addition, the mutual penetration of elements caused by temperature changes may lead to a colourful appearance. Originality/value The custom continuous AM technology enables the fabrication of a glass matrix with 3D structural features. The precise positioning technology of the glass matrix is expected to be applied more widely in functional parts.
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Cai, Hua, Yong Sun, Xian Zhang, Lei Zhang, Hui Liu, Qing Li, Tiezhu Bo, Dongzhan Zhou, Chen Wang et Jiao Lian. « Reduction Temperature-Dependent Nanoscale Morphological Transformation and Electrical Conductivity of Silicate Glass Microchannel Plate ». Materials 12, no 7 (11 avril 2019) : 1183. http://dx.doi.org/10.3390/ma12071183.
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Lead silicate glasses are fundamental materials to a microchannel plate (MCP), which is a two dimensional array of a microscopic channel charge particle multiplier. Hydrogen reduction is the core stage to determine the electrical conductivity of lead silicate glass MCP multipliers. The nanoscale morphologies and microscopic potential distributions of silicate glass at different reduction temperatures were investigated via atomic force microscope (AFM) and Kelvin force microscopy (KFM). We found that the bulk resistance of MCPs ballooned exponentially with the spacing of conducting islands. Moreover, bulk resistance and the spacing of conducting islands both have the BiDoseResp trend dependence on the hydrogen reduction temperature. Elements composition and valence states of lead silicate glass were characterized by X-ray photoelectron spectroscopy (XPS). The results indicated that the conducting island was an assemblage of the Pb atom originated from the reduction of Pb2+ and Pb4+. Thus, this showed the important influence of the hydrogen temperature and nanoscale morphological transformation on modulating the physical effects of MCPs, and opened up new possibilities to characterize the nanoscale electronic performance of multiphase silicate glass.
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Laorodphan, Nattapol, et Jiratchaya Ayawanna. « BaO-Al2O3-SiO2-B2O3 Glass-Ceramic SOFCs Sealant : Effect of ZnO Additive ». Key Engineering Materials 751 (août 2017) : 455–60. http://dx.doi.org/10.4028/www.scientific.net/kem.751.455.
Texte intégralRésumé :
The crystallization of planar solid oxide fuel cells (SOFCs) sealant glasses in the systems BaO-Al2O3-SiO2-B2O3 (BaBS) and BaO-Al2O3-SiO2-B2O3-ZnO (BaBS-Zn) was investigated via both X-ray diffractometer and scanning electron microscopy with energy dispersive spectroscopy. The effect of nucleation heat-treatment of the BaBS glass at different temperature for 5 hours, i.e. 550 and 590 °C, on the crystallization behavior was also studied. Thermal expansion profiles of the glasses indicate that both glasses have a low sealing temperature. XRD patterns of all BaBS glass-ceramics, devitrified at 800 °C for 30 hours, show that Ba2Si3O8, BaAl2Si2O8, Ba3B2O6 and some unknown crystalline phases were found. It was also found that crystalline size of unknown barium aluminosilicate with low silicon content depends on the nucleation heat-treatment temperature. For the ZnO-containing glass, ZnO reduces the coefficient of thermal expansion value of glass and causes the devitrification of large needle-like barium zinc silicate phases. The crack at the YSZ/BaBS-Zn glass-ceramic interface was also observed. Two barium silicate phases, which are BaZnSiO4 and BaZn2Si2O7 were devitrified in ZnO-containing glass-ceramic.