Academic literature on the topic 'Alkali metal silicate'
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Journal articles on the topic "Alkali metal silicate"
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Krumrine, Paul H., Michael Lefenfeld, and Gregory A. Romney. "Alkali Metal Silicides: A New Material for Heavy-Oil Production Processes." SPE Journal 21, no. 01 (2016): 22–31. http://dx.doi.org/10.2118/169490-pa.
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Summary Alkali-metal silicides are a new class of materials that provide thermal, chemical, and immiscible gas-drive benefits in one treatment. Not previously known in oilfield applications, these materials are energy-dense chemicals that generate heat, hydrogen, and an alkali silicate after reaction with reservoir water. The reaction is only limited by the availability of water in any form; in a closed environment, one can generate pressures >10,000 psi (>68.9 MPa). One can disperse alkali-metal silicides in various hydrocarbon fluids to facilitate placement deep in the reservoir, or one can coat them to allow a time-delayed reaction. One can mill the powders to submicron size for optimum injectivity in high-permeability reservoirs or zones. This combination of reaction-product properties makes silicides particularly applicable for the recovery of heavier crude oils. Because the chemical reaction occurs in situ, silicides are not subject to the thermal-inefficiency limitations of conventional thermal-enhanced-oil-recovery processes at depth. Further, the resulting hydrogen and silicate reaction products represent a “green” chemistry approach that may reduce the environmental impact of oil-recovery operations. This paper discusses the potential impacts of heat, hydrogen, and alkali generated from alkali-metal silicide and presents bench-scale high-permeability unconsolidated-sandpack linear-flood results demonstrating recovery efficiencies up to 93% of original oil in place (residual oil saturation = 0.058). Results also show that alkali-metal silicides can provide accelerated oil production, as much as 20% faster than comparable chemical technologies.
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Liang, Jian-Jie, Alexandra Navrotsky, Thomas Ludwig, Hans J. Seifert, and Fritz Aldinger. "Enthalpy of Formation of Rare-earth Silicates Y2SiO5 and Yb2SiO5 and N-containing Silicate Y10(SiO4)6N2." Journal of Materials Research 14, no. 4 (1999): 1181–85. http://dx.doi.org/10.1557/jmr.1999.0158.
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The enthalpies of formation of two rare-earth silicates (Y2SiO5 and Yb2SiO5) and a N-containing rare-earth silicate Y10(SiO4)6N2 have been determined using high-temperature drop solution calorimetry. Alkali borate (52 wt% LiBO2·48 wt% NaBO2) solvent was used at 800 °C, and oxygen gas was bubbled through the melt. The nitrogen-containing silicate was oxidized during dissolution. The standard enthalpies of formation are for Y2SiO5, Yb2SiO5, and Y10(SiO4)6N2, respectively, –22868.54 ± 5.34, –22774.75 ± 8.21, and –14145.20 ± 16.48 kJ/mol from elements, and –52.53 ± 4.83, –49.45 6 ± 8.35, and –94.53 ± 11.66 kJ/mol from oxides (Y2O3 or Yb2O3, SiO2) and nitride (Si3N4). The silicates and N-containing silicate are energetically stable with respect to binary oxides and Si3N4, but the N-containing silicate may be metastable with respect to assemblages containing Y2SiO5, Si3N4, and SiO2. A linear relationship was found between the enthalpy of formation of a series of M2SiO5 silicates from binary oxides and the ionic potential (z/r) of the metal cation.
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Matos, Israel R. Montoya. "Influence of Alkali Metal Ions on the Structural and Spectroscopic Properties of Sm3+-Doped Silicate Glasses." Ceramics 6, no. 3 (2023): 1788–98. http://dx.doi.org/10.3390/ceramics6030109.
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In the present work, the influence of alkali ions (Li, Na, K) on the structural and spectroscopic properties of silica glasses doped with Sm3+ was investigated. Infrared and Raman spectroscopy techniques were used to investigate the structural properties of the alkali silicate glasses. The optical absorption showed bands characteristic of Sm3+ ions in alkali silicate glasses, and this was investigated. The Judd–Ofelt theory was applied to evaluate the phenomenological intensity parameters (Ω2, Ω4, and Ω6) of the optical absorption measurements. The multi-channel visible and near infrared emission transitions originating from the 4G5/2-emitting state of the Sm3+ in alkali silicate glasses with a maximum phonon energy of ~1050 cm−1 were investigated. From the evaluated Judd–Ofelt parameters, radiative parameters such as spontaneous emission probabilities, radiative lifetimes, branching ratios, and stimulated emission cross-sections were calculated. The recorded luminescence spectra regions revealed intense green, orange, red, and near-infrared emission bands, providing new traces for developing tunable laser and optoelectronic devices.
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Salguero, Tina T., Darrah Johnson-McDaniel, Christopher A. Barrett, Asma Sharafi, Richard Weimar, and Terra Blevins. "Nanoscience of Metal Silicate-Based Pigments." MRS Proceedings 1618 (2014): 161–66. http://dx.doi.org/10.1557/opl.2014.465.
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ABSTRACTThe colored component of several important ancient pigments, including Egyptian blue and Han blue, are based on alkali earth copper tetrasilicate materials. In recent work, we have found that these layered materials can be chemically exfoliated into their constituent monolayers to provide alkali earth copper tetrasilicate nanosheets—defined by nanometer thickness and lateral dimensions that are on the order of several microns. The facile exfoliation of these materials into nanosheets is especially surprising in view of their long history on artifacts under a variety of environmental conditions, and we have examined the issue of whether archaeological samples are affected by this exfoliation mechanism. We have characterized the properties of these nanosheets by an array of analytical techniques, including powder x-ray diffraction, photoluminescence measurements, and Raman spectroscopy. In all cases, we observe differences between nanosheet and bulk samples that originate from the loss of coupling between layers when going from three-dimensional to two- dimensional structures. Both CaCuSi4O10 nanosheets (derived from Egyptian blue) and BaCuSi4O10 nanosheets (derived from Han blue) have strong near-infrared luminescence properties like their bulk counterparts, yet they are amenable to modern solution processing methods. We have demonstrated ink jet printing with CaCuSi4O10 nanosheet inks, as well as the fabrication of nanosheet-based papers. Potential applications for these materials include NIR-based biomedical imaging and security inks.
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Kudina, Elena F., Natalia S. Vinidiktova, Vladeta Jevremović, and Radovan Nikolić. "Development of Coatings Based on Modified Epoxide Binder for Metal Surface Protection." Applied Mechanics and Materials 806 (November 2015): 135–40. http://dx.doi.org/10.4028/www.scientific.net/amm.806.135.
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Epoxy-silicate modifiers were obtained by a sol-gel procedure from the alkali-silicate solutions and their effect on physico-mechanical properties of the coatings based on the binary epoxide binder were investigated. It is shown that pretreatment of the metal surface effects strength of adhesive bonding with the epoxide coating.
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Zheng, Jian, Le Huang, Panpeng Wei, et al. "Molecular Insights into Adsorption and Diffusion Mechanism of N-Hexane in MFI Zeolites with Different Si-to-Al Ratios and Counterions." Catalysts 12, no. 2 (2022): 144. http://dx.doi.org/10.3390/catal12020144.
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The effect of the silicon to aluminum ratio (SAR) and alkali metal cations on adsorption and diffusion properties of ZSM-5 and silicate-1 zeolites was investigated using n-hexane as the model probe via giant canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. A wide range of SAR was considered in this study to explore the possible adsorption sites in the zeolites. The findings show that, at 298 K and 423 K, adsorption and diffusion of n-hexane on/in low SAR (≤50) H-ZSM-5 models were promoted due to the preferable distribution of n-hexane in straight channels and enhanced interaction between protons and n-hexane molecules (about 24 kcal·mol−1). In alkali metal cation (i.e., Na+ and K+) exchanged ZSM-5, the alkali metal cations affected transport of molecules, which led to significant differences in their adsorption and diffusion properties compared to HZSM-5. In the Na+ and K+ systems, lower saturated adsorption capacities were predicted compared to that of silicate-1, which could be attributed to the decrease in effective void size posed by alkali–metal cations. In addition, simulation results also suggested that the T9 and T3 are the most likely sites for n-hexane adsorption, followed by T2, T5, and T10. Findings of the work can be beneficial to the rational design of high-performance zeolite catalysts for n-hexane conversion.
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Jiang, Xintai, Fenglin Lu, Jiantao Ju, Wenke Guo, and Jian Zu. "The Influence of Alkali Metals on the Sintering Mineralization Process of Iron Ore." Materials 18, no. 2 (2025): 227. https://doi.org/10.3390/ma18020227.
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To investigate the influence of alkali metal compounds in different forms on the sintering mineralization process of iron ore, the basic sintering characteristics of iron ore with alkali metal contents ranging from 0 to 4% were measured using the micro-sintering method, and the influence mechanism was analyzed using thermodynamic analysis and first-principles calculations. The results showed that (1) the addition of KCl/NaCl increased the lowest assimilation temperature (LAT) and the index of liquid-phase fluidity (ILF), while that of K2CO3/Na2CO3 decreased the LAT but increased the ILF of iron ore. (2) The pores formed by the volatilization of KCl/NaCl suppressed the diffusion of Fe3+ and Ca2+, which inhibited the formation of silico-ferrite of calcium and aluminum (SFCA). The addition of K2CO3/Na2CO3 promoted the formation of a silicate liquid phase with better fluidity, intervening in the solid-phase reaction between iron ore and CaO. (3) The alkali metal compounds in different forms concentrated in silicate but showed lower levels of distribution in iron-bearing minerals in the form of a solid solution. Furthermore, the formation of an alkali metal-bearing solid solution decreased the microhardness of minerals. This decrease in microhardness and in the content of the SFCA bonding phase directly contributed to the decrease in the compressive strength of the sinter.
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Glenn, Michael, Jessica A. Allen, and Scott W. Donne. "Silicate Formation in a Ternary Alkali Metal Carbonate Melt." Energy & Fuels 33, no. 11 (2019): 12008–15. http://dx.doi.org/10.1021/acs.energyfuels.9b02356.
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Brykov, A. S., and V. I. Korneev. "Production and usage of powdered alkali metal silicate hydrates." Metallurgist 52, no. 11-12 (2008): 648–52. http://dx.doi.org/10.1007/s11015-009-9108-5.
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P V, Gokul, Megha S Murali, Mekha M Sivan, Nijo J Zachariah, and Joshua Jathin Vaz. "An Experimental Study on Performance of Two-Part Geopolymer Concrete Using Natural Binders and Activators." E3S Web of Conferences 529 (2024): 01007. http://dx.doi.org/10.1051/e3sconf/202452901007.
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The study investigates the characteristics of geopolymer concrete, employing sodium silicate and sodium hydroxide as activators instead of cement. In conventional construction practices, binders like fly ash, ground granulated blast furnace slag (GGBS) are commonly combined with alkali solutions. The manufacturing process of geopolymer relies on various alkaline activators. In this research, GGBS is replaced with sodium hydroxide and sodium silicate as activators. GGBS is recognized for its ability to enhance the workability and strength of geopolymer concrete, exhibiting favorable mechanical properties, resistance to chemicals, minimal shrinkage, environmental friendliness and exceptional durability. Furthermore, there are still certain drawbacks to geopolymer concrete, such as the fact that alkaline solutions are difficult to handle and apply because they are viscous, corrosive, difficult to transport, as well as challenging to store in huge quantities. A two part geopolymer concrete consists of two main components. An activator solution and a binder solution. The activator solution typically contains alkali metal hydroxides or silicates, while the binder solution contains aluminosilicate material such as fly ash or metakaolin. When mixed together, these solutions undergo a chemical reaction that forms a solid and durable geopolymer material.
Dissertations / Theses on the topic "Alkali metal silicate"
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F, SARRI. "Optical microstructuring of alkali metal nanoparticle coatings on porous silica substrates induced by Bessel beam." Doctoral thesis, Università di Siena, 2019. http://hdl.handle.net/11365/1075534.
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The ability to control atomic adsorption/desorption processes by light as well as nanoparticle growth
on proper substrates is nowadays recognized as a promising technique in nanotechnology. This
subject is a part of a rising area of research devoted to the development of micro and nanophotonic
devices, sensors, metamaterials. The experimental work in this thesis aims at obtaining ordered
microstructures exploiting atomic desorption phenomena such as LIAD (Light Induced Atomic
Desorption). The suitable substrates consist in nanoporous silica matrices sealed inside cells and
exposed to alkaline atom vapor. A Gaussian beam generated by a laser, transformed in Bessel beam
by a conical shape lens, has been used as desorption light: in such way, the nanoparticles are created
on the pores and they are arranged following the Bessel beam profile, obtaining then the order
microscopic structure. More efficiently a coating of alkali metal nanoparticles has been grown on the
porous substrate due to LIAD induced by a Hg lamp and then the atomic desorption induced by a
Bessel beam has been responsible for the redistribution of the generated nanoparticles in the
micrometric concentric ring structure following the beam profile. The experiments have been
performed using different alkaline atom vapors, moreover porous silica samples with different pore
size and lasers with different wavelengths have been used.
During the work, the experimental setup and procedure have been optimized, evaluating the best
conditions for obtaining a well defined structure, in particular as regards the power emitted by the
desorbing lasers and the lighting time intervals for the porous silica samples. Through adjustments to
these parameters multiple, overlapping or side-by-side, illuminations, without incurring erasing
phenomena, have been possible thus creating complex structures.
The structures thus obtained, whether simple or complex, act as micrometric masks made out of
nanoparticles, and they are persistent and reversible. These masks can be detected by illuminating
them with laser light and observing the ring-shaped pattern produced by diffraction.
The generated structures have been systematically analyzed verifying the effective formation of the
nanoparticles by detection of their absorption spectra, observing the microstructures under a
microscope and recording them with a CCD camera. By an image analysis software, the concentric ring
pattern, corresponding to a 2D quasi-Bessel function, has been studied, evaluating the spacing ring
distance from its Fourier transform using the FFT algorithm; in this way, the relationship between the
characteristics of the Bessel beam, the wavelength of the radiation and the physical characteristics of
the conical lens have been verified. Also, images of the ring-shaped pattern obtained by diffraction
have also been registered, in order to estimate the contrast with the background and its persistence
on the sample.
The experimental results on this thesis suggest a new technique for the laser structuring of alkali metal
nanoparticles in ordered patterns on micrometric scale resolution promising for many applications in
all-optical photonic devices.
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Harm, Sascha [Verfasser], and Bettina [Akademischer Betreuer] Lotsch. "Alkali metal ortho thioaluminates, -silicates and -phosphates as solid electrolytes for all-solid-state batteries / Sascha Harm ; Betreuer: Bettina Lotsch." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1215499841/34.
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Jago, Christopher Paul. "Metal- and alteration-zoning, and hydrothermal flow paths at the moderately-tilted, silica-saturated Mt. Milligan copper-gold alkalic porphyry deposit." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/609.
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The Mt. Milligan deposit is a tilted (~45°) Cu-Au alkalic porphyry located 155 km northwest of Prince George, B.C., Canada. It is the youngest of the BC alkalic porphyry deposits, all of which formed between 210 to 180 Ma in an extensive belt of K-enriched rocks related to the accretion of the Quesnellia-Stikinia superterrane to ancestral North America. Mt. Milligan has a measured and indicated resource of 205.9 million tonnes at 0.60 g/t Au and 0.25% Cu containing 3.7 million oz. gold, and 1.12 billion lb. copper.
Shoshonitic volcanic and volcaniclastic andesites host mineralization. These have been intruded by a composite monzonitic stock (MBX stock), and associated sill (Rainbow Dike). Early disseminated chalcopyrite-magnetite and accessory quartz veins are associated with K-feldspar alteration in the MBX stock. A halo of biotite alteration with less extensive magnetite replaces host rocks within a ~150 m zone surrounding the stock, while K-feldpsar alteration extends along the Rainbow Dike and permeable epiclastic horizons. Peripheral albite-actinolite-epidote assemblages surround the K-silicate zone. Albite-actinolite occurs at depth, and epidote dominates laterally. Copper and Au grade are maximal where the albite-actinolite assemblage overprints biotite alteration. Gold grade is moderate in association with epidote, whereas Cu is depleted. The post-mineral Rainbow Fault separates the core Cu-rich zone from a downthrown Au-rich zone. A similar zonation of metals occurs in the hanging-wall (66 zone), where a Cu-bearing, potassically-altered trachytic horizon transitions to a funnel-shaped zone of pyrite-dolomite-sericite-chlorite alteration with elevated gold.
Sulfide S-isotope compositions range from -4.79 δ34S in the central Cu-Au orebody to near-zero values at the system periphery, typical of alkalic porphyries. Sulfur isotope contours reflect the magmatic-hydrothermal fluid evolution, and indicate late-stage ingress of peripheral fluids into the Cu-Au zone. Carbonate C- and O-isotope compositions corroborate the magmatic fluid path from the Cu-Au rich zone to Au-rich zone with decreasing depth. Strontium isotopic compositions of peripheral alteration minerals indicate a laterally increasing meteoric fluid component. Changes in major- and trace element composition of epidote and pyrite across the deposit are also systematic. These provide additional vectors to ore, and confirm the kinematics of the Rainbow Fault.
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Song, Yang. "Design of metal silicide nanoparticles in molten salts : electrocatalytic and magnetic properties." Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS498.pdf.
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Les siliciures de métaux de transition sont une famille de composés intermétalliques, qui ont été largement étudiés en tant que matériaux fonctionnels dans les circuits intégrés, la thermoélectricité, la supraconductivité, le magnétisme et la catalyse hétérogène. La nanostructuration offre la possibilité repousser les frontières de la science de ces matériaux avec de nouvelles phases et des propriétés diverses. Cependant, l'énergie de liaison relativement élevée des siliciures de métaux de transition nécessite généralement une température élevée pour leur formation, ce qui n'est pas propice à la conception de nanomatériaux et n'est pas compatible avec les méthodes de synthèse colloïdales traditionnelles. Dans cette thèse, des synthèses en sels fondus basées sur l'insertion d'éléments dans des nanoparticules sont développées. Des nanoparticules de siliciure de métal de transition (M-Si, M=Ni, Fe, NiFe, Co) et un silicophosphure de nickel ternaire sont cristallisés dans des solvants inorganiques à haute température, où un environnement dilué et sans carbone est fourni. Les nanoparticules de siliciures obtenues sont étudiées en électrocatalyse de l'oxydation de l'eau alcaline et du magnétisme. Les siliciures de NiFe démontrent une activité et une stabilité exceptionnelles résultant d'une structure originale cœur-coquille-coquille générée in situ, tandis que les nanoparticules de CoSi riches en défauts présentent un ferromagnétisme inhabituel. De plus, l'étude des nanoparticules de silicophosphure donne un aperçu de la conception de matériaux multinaires dans les sels fondus et du rôle des éléments non métalliques dans l’électrocatalyse de l’électrolyse de l’eau<br>Transition metal silicides are a family of intermetallic compounds, which have been widely studied as functional materials in integrated circuits, thermoelectricity, superconductivity, magnetism and heterogeneous catalysis. Nanostructuration offers the opportunity to extend the frontier of silicon-based materials science with novel phases and diverse properties. However, building transition metal silicides encompassing relatively high energy bonds usually requires high temperatures, which are not conducive for nanomaterial design and not compatible with the traditional colloidal synthesis methods. In this thesis, molten salts syntheses based on element insertion into nanoparticles are developed. Transition metal silicide nanoparticles (M-Si, M=Ni, Fe, NiFe, Co) and a ternary nickel silicophosphide are crystallized in high temperature inorganic solvents, where a diluted and carbon-free environment is provided. The obtained silicide nanoparticles are investigated in electrocatalysis of alkaline water oxidation and magnetism. NiFe silicides demonstrate outstanding activity and stability arising from an original in situ generated core-shell-shell structure, while defect-rich CoSi nanoparticles show an unusual surface related ferromagnetism. Moreover, the study of silicophosphide nanoparticles provides an insight in multinary material design in molten salts and the role of nonmetal elements in overall alkaline water splitting electrocatalysis
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Castillo, Rodrigo. "Synthesis of silicon- and germanium-rich phases at high-pressure conditions." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-207708.
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The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge.
Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow.
By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6.
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Lafond, Fabien. "Hybrid functionals approach for the study of the properties of complex materials for photovoltaic applications." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0308.
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Les propriétés électriques des semiconducteurs sont fortement influencées par le type de dopants et défauts insérés ou formés lors de leur synthèse. Dans le domaine du photovoltaïque, ces défauts vont fortement dégrader l’efficacité et la durabilité des cellules solaires. Dans ce contexte, les méthodes de simulation ab-initio, Hartree-Fock (HF) ou la théorie de la fonctionnelle de la densité (DFT), sont pertinentes pour une compréhension de ces différents effets nécessaire à l’optimisation des matériaux. Cependant, l’obtention d’une bonne description des propriétés requiert l’utilisation d’approches sophistiquées, comme GW, coûteuses en temps de calcul. Ainsi, les approches pragmatiques basées sur les fonctionnelles hybrides, combinant HF et DFT, représentent une alternative intéressante. Dans un premier temps, des fonctionnelles hybrides ont été optimisées afin d’avoir une bonne description de l’énergie de bande interdite pour différents composés : Si, Ge, SiGe, les III-V et les chalcopyrites (CIGS). Les résultats obtenus avec cette approche semi-empirique ont été confrontés à ceux de la littérature et notamment à ceux obtenus au niveau GW. La description des propriétés électroniques est similaire à celle obtenue au niveau GW. L’évolution en température de différentes données thermodynamiques a aussi été abordée via l’approximation quasi-harmonique Pour celles-ci et les matériaux étudiés, les approches hybrides n’apportent pas d’amélioration par rapport aux fonctionnelles existante mais permettent une description cohérente des matériaux. Dans un second temps, ces fonctionnelles ont été utilisées pour réaliser une étude systématique de l’impact de la composition chimique sur les propriétés des CIGS pour des cellules solaires de type tandem. Tout d’abord, elles ont permis de déterminer les compositions, propriétés structurales et électroniques des CuGaxIn1-x(SySe1-y)2 avec des gaps donnés pour ce type d’application. Ensuite, l’effet de l’insertion des alcalins dans les CIGS a été abordé. L’accent a été porté sur la substitution du Cu par le Li, Na, K, Rb et Cs. Leur impact sur le gap a été interprété en terme d’évolution structurale et stabilité thermodynamique de différentes phases cristallines pouvant exister dans le matériau. Enfin, les défauts ponctuels de H, Fe et B dans le silicium ont été modélisés pour une étude concernant la dégradation induite par la lumière à haute température, un des mécanismes de vieillissement des cellules à base de silicium<br>Electrical properties of semiconductors are strongly influenced by the types of dopants and defects inserted or formed during the synthesis of materials. In the field of photovoltaics, these defects leads to various metastabilities and can degrade the efficiency and durability of solar cells. In this context, ab-initio simulation methods, such as Hartree-Fock (HF) or the one implemented in the framework of density functional theory (DFT), are relevant to understand these behaviours and thus optimise the photovoltaic materials. However, a good qualitative and quantitative description of properties requires sophisticated but time consuming method like GW. An interesting alternative can be provided by hybrid functionals, which combine HF and DFT. Firstly, hybrid functionals were optimised in order to accurately described the band gap for different compounds by varying the percentage of HF exact-exchange in the exchange term of the PBE and PBEsol functionals from the GGA approximation of DFT. The materials investigated were Si, Ge, SiGe, III-V and chalcopyrites. Results obtained by this approach were confronted to the one from the literature. The description of the electronic properties matched the one from GW. Temperature evolution of various thermodynamic properties was calculated via the quasi-harmonic approximation. In this approximation and for the range of studied materials, optimised hybrid functionals do not bring an enhancement compared to existing functionals. Nevertheless, they bring a coherent description of the materials. Secondly, these optimised hybrid functionals were used to systematically describe the impact of chemical composition on chalcopyrite’s properties for tandem solar cells. First, they enable the determination the compositions, structural and electrical properties of CuGaxIn1-x(SySe1-y)2 for band gap specific to this kind of application. As alkali metals leads to major enhancement of chalcopyrite efficiency, the effect of their incorporation in chalcopyrite bulk was address. Highlight was put on the substitution of copper by Li, Na, K, Rb and Cs. Their impact on the band gap was interpreted via the structural evolution and the thermodynamique stability of the different crystallines phases that can exists within the material. Finally, H, Fe and B point defects in silicon were simulated for a preliminary study on the light and elevated temperature induced degradation which is one of the ageing process of the silicon solar cells
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Creazzo, Fabrizio. "Oxygen evolution reaction at cobalt oxides/water interfaces : heterogeneous electrocatalysis by DFT-MD simulations & metadynamics Ab initio molecular dynamics study of an aqueous NaCl solution under an electric field Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts Ionic Diffusion and Proton Transfer in Aqueous Solutions under an Electric Field: State-of-The-Art Ionic diffusion and proton transfer of MgCl2 and CaCl2 aqueous solutions: an ab initio study under electric field DFT-MD of the (110)-Co 3 O 4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment Enhanced conductivity of water at the electrified air–water interface: a DFT-MD characterization Ions tune interfacial water structure and modulate hydrophobic interactions at silica surfaces." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE012.
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Dans cette thèse, des simulations DFT-MD couplées à des techniques inno-vantes de métadynamique, sont appliquées pour acquérir une compréhensionglobale des interfaces aqueuses d'oxyde de cobalt Co3O4 et CoO(OH) dansla catalyse de la réaction d'évolution de l'oxygène (OER), et ainsi éventuellement aider à la conception de nouveaux catalyseurs basés sur des matériaux non précieux, un domaine clé de la recherche scientifique et technologique, particulièrement important pour l'économie de l'hydrogène, pour les technologies vertes dans une période de temps avec une demande toujours plus croissanteen énergie verte. Dans cette thèse, nous révélons étape par étape les mécanismes de l'OER sur les électrocatalyseurs aqueux d'oxyde de cobalt Co3O4 etCoO(OH) via de nouvelles techniques de métadynamique.Jusqu'à présent, la littérature n'a jamais pris en compte les modificationsau niveau atomique de la structure des électrodes ainsi que de l'eau interfaciale dans leur modélisation des processus OER. Ce manque de connaissances représente clairement un obstacle important au développement de catalyseurs améliorés, qui pourrait être surmonté en utilisant des méthodes capables de suivre les caractéristiques catalytiques de l'OER à l'échelle atomique. Pour la première fois, nous montrons combien il est important de prendre en considération la présence de l'environnement aqueux dans la caractérisation structurale des surfaces du catalyseur, c'est-à-dire (110)-Co3O4 et (0001)-CoO(OH) dans ce travail. Une caractérisation détaillée des propriétés chimiques et physiques des interfaces aqueuses est fournie (la structure, la dynamique, la spectroscopie, le champ électrique), pour les surfaces (110)-Co3O4 et (0001)-CoO(OH) en contact avec l'eau liquide.Une étude détaillée de l'OER est présentée non seulement du point de vue descatalyseurs, mais aussi en abordant le rôle de l'environnement de l'eau dans leprocessus catalytique, ce qui n'a pas été fait auparavant dans la littérature. En conséquence, l'OER en phase gazeuse et en phase liquide sont étudiés ici auxinterfaces aqueuses (110)-Co3O4 et (0001)-CoO(OH) en adoptant une nouvelleapproche de métadynamique d'échantillonnage amélioré, capable d'identifieret caractériser les mécanismes de réaction chimique et d'intégrer pleinement lerôle des degrés de liberté du solvant, permettant ainsi de dévoiler des réactivités chimiques d'une complexité remarquable. L'énergétique, la cinétique et la thermodynamique derrière l'OER sont donc trouvées à ces surfaces d'oxyde de cobalt à l'interface avec l'eau<br>In this thesis, DFT-MD simulations, coupled with state-of-the-art metadynamics techniques, are applied to gain a global understanding of Co3O4 and CoO(OH) cobalt oxide aqueous interfaces in catalyzing the oxygen evolution reaction (OER), and hence possibly help in the design of novel catalysts basedon non-precious materials, a current key field of research in science and technology, especially of importance for the hydrogen economy, for green technology in a period of time with an ever more growing demand in green-energy. In this thesis, we step-by-step reveal the OER mechanisms on spinel Co3O4 andCoO(OH) cobalt aqueous electrocatalysts carefully and rationally via novelmetadynamics techniques.Up to now, the literature has never taken into account the atomistic modifications on the electrode structure as well as on the interfacial water into their modeling of OER processes. Such lack of knowledge clearly represents a significant hurdle toward the development of improved catalysts, which couldbe overcome by employing methods able to track the catalytic features of theOER at the atomistic scale. For the first time, we show how important itis to take into consideration the presence of the liquid water environment inthe structural characterization of catalyst surfaces, i.e. for (110)-Co3O4 and(0001)-CoO(OH) in this work. A detailed characterization of chemical andphysical properties of the aqueous interfaces is provided (i.e. structure, dynamics, spectroscopy, electric field), for the (110)-Co3O4 and (0001)-CoO(OH)aqueous surfaces.A study of the OER is presented not only by looking at the catalysts, butalso by addressing the role of the water environment in the catalytic process,not done before in literature. Accordingly, both gas-phase and liquid-phaseOER are here investigated at the (110)-Co3O4 and (0001)-CoO(OH) adoptinga novel enhanced sampling metadynamics approach able to address a widerange of chemical reaction mechanisms and to fully include the role of thesolvent degrees of freedom, allowing to unveil reaction networks of remarkablecomplexity. The energetics, kinetics and thermodynamics behind the OER aretherefore found at these cobalt oxide surfaces
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Lu, Ting-Hsuan, and 呂庭萱. "The Synthesis and Characterization of Narrow-Band Eu2+-doped Alkali Metal Silicate Phosphors and Their Application in Back Light Source for LCDs." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/83b5mn.
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碩士<br>國立交通大學<br>應用化學系碩博士班<br>108<br>In this study, narrow-band Eu2+-doped alkali metal silicate phosphors were prepared by solid state synthesis. This study investigate and describe two series of Mn (Li3SiO4)n:Eu2+ (n=2 and 4). The crystal structure belongs to the UCr4C4 type. The crystal structure and luminescence properties were characterized by using powder X-ray diffraction, fluorescence spectrometer, quantum efficiency measurement, thermal quenching experiment, and investigation scanning electron microscope. Finally, we evaluate the applications by fabrication of white light emitting diodes.
In this thesis, Eu2+ is used as an activator in the alkali metal silicate phosphors. The excitation range is from 330 nm to 450 nm. Due to the rigidity of the main structure, the emission band was narrow, and the full width at half maximum ( FWHM ) is about 41.6 nm. In the thermal quenching experiments, the heat resistance is as high as 300 °C. Finally, in the results of LED packaging, we use the 450 nm blue LED chip the red phosphor K2SiF6:Mn4+ combinated with the title phosphors in this study. This white light-emitting diode devices was found to show with wide NTSC color gamut of about 111%.
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Chen, Yu-Chi, and 陳羽綺. "Preparation and Application of Alkyl Silicone Polymer Noble Metal Nanoparticle Catalyst Ink." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/17740975276221108147.
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碩士<br>國防大學理工學院<br>化學工程碩士班<br>102<br>In this study, the preparation of St-co-MPS copolymer with both styrene(St) monomer and γ-methacryloxypropyltrimethoxysilane (γ-MPS) monomer by free radical polymerization. Poly(St-co-MPS)/Pd was prepared via self-reduction of palladium ions by St-co-MPS oligomer without using any reducing agent or surfactant. It was shown that Pd was reduced by the chain-end sulfate groups of styrene when copolymer reacted with the metallic ions. These St-co-MPS copolymer was characterized by 13C-NMR, 29Si-NMR and FTIR to confirm polymer composition and quantity sulfonation, and those self-assembly polymer-metal nanocomposites were characterized by electron microscopy (TEM), observe the stability of LU Misizer(LUM).
The Poly(St-co-MPS)/Pd used as ink for catalytic pattern of glasses, which allows to from the metallic pattern by electroless deposition. The cross-linking extend of Poly(St-co-MPS)/Pd ink and glasses dipping with different pH condition was characterized by X-ray photoelectron spectroscope(XPS) to enhance the adhesion of the Poly(St-co-MPS)/Pd ink and glass substrate. The pattern thickness of Ni layer about 8.51 μm.
Finally, we used Inkjet printing metallization process has been used in the fabricated of mobile antenna on special glass case, The WWAN five band antenna was made on the new glass case substrate by the printing of the catalyst activation and electroless plating forming the metal pattern. It will simplify the institutions of the antenna, and resolve the configuration problems of the limited space in the mobile phone's.
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Liu, Chia-lin, and 劉佳琳. "High-Temperature, High-Pressure Hydrothermal Synthesis, Crystal Structures and Properties of Alkaline Earth Metal-Containing Uranium Silicates." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/08791413924387255998.
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碩士<br>國立中央大學<br>化學學系<br>103<br>Three new alkaline earth metal-containing uranium silicates, Ba10[(UO2)2(Si2O7)4] (A1),K2Ca4[(UO2)(Si2O7)2] (A2) and K4Ca[(UO2)Si4O12] (A3), were synthesized by the high-temperature, high-pressure hydrothermal method, and structurally characterized by powder and single X-ray diffraction. These compounds were further characterized by EDS, PL and SHG.
Compound A1 is a barium-containing uranium silicate. The crystal structure consists of Sorosilicates [Si2O7] which connect adjacent UO6 tetragonal bipyramids via four equatorial oxygen atoms to form 2D layers in ac plane. The Ba2+ cations are located at sites in the intralayer and interlayer regions. This compound is the first Ba-containing uranium silicate synthesized using the high-temperature, high-pressure hydrothermal method.
Compound A2 is a uranium(VI) silicate. The structure consists of UO6 tetragonal bipyramids which are linked by Sorosilicate [Si2O7] units to form 1D chains along the a axis. The Ca2+ and K+ cations are located at sites in the interchain regions. This 1D chain structure is very rare in the literature.
Compound A3 is a uranium(VI) silicate. It’s structure consists of [Si4O12] units connecting with four UO6 tetragonal bipyramids to form a 3D framework. The K+ cations are located in the channels and the Ca2+ cations are located between each set of two UO6 polyhedra in the c direction. This arrangement produces a linear -U-O-Ca-O-U- chain along the c axis.
Books on the topic "Alkali metal silicate"
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Parker, Philip M. The World Market for Silicates and Commercial Alkali Metal Silicates: A 2007 Global Trade Perspective. ICON Group International, Inc., 2006.
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The World Market for Silicates and Commercial Alkali Metal Silicates: A 2004 Global Trade Perspective. Icon Group International, Inc., 2005.
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Parker, Philip M. The 2007 Import and Export Market for Silicates and Commercial Alkali Metal Silicates in India. ICON Group International, Inc., 2006.
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Parker, Philip M. The 2007 Import and Export Market for Silicates and Commercial Alkali Metal Silicates in China. ICON Group International, Inc., 2006.
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Parker, Philip M. The 2007 Import and Export Market for Silicates and Commercial Alkali Metal Silicates in United States. ICON Group International, Inc., 2006.
Find full textBook chapters on the topic "Alkali metal silicate"
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McCormick, A. V., A. T. Bell, and C. J. Radke. "Effect of Alkali Metal Cations on Silicate Structures in Aqueous Solution." In ACS Symposium Series. American Chemical Society, 1988. http://dx.doi.org/10.1021/bk-1988-0368.ch014.
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Marvila, M. T., A. R. G. Azevedo, E. B. Zanelato, et al. "Variation of the Silica Module for Dosing Activated Alkali Mortars." In Characterization of Minerals, Metals, and Materials 2021. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65493-1_62.
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Clayton, Dwight A., Hector Santos-Villalobos, N. Dianne Bull Ezell, Joseph Clayton, and Justin Baba. "Automated Detection of Alkali-Silica Reaction in Concrete Using Linear Array Ultrasound Data." In The Minerals, Metals & Materials Series. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-030-04639-2_87.
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Clayton, Dwight A., Hector Santos-Villalobos, N. Dianne Bull Ezell, Joseph Clayton, and Justin Baba. "Automated Detection of Alkali-Silica Reaction in Concrete Using Linear Array Ultrasound Data." In The Minerals, Metals & Materials Series. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-68454-3_11.
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Caldas, P. H. C. H., A. R. G. Azevedo, and M. T. Marvila. "Mechanical Properties of Silica Fume-Based Mortars Alkaline Activated by NaOH." In The Minerals, Metals & Materials Series. Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-22576-5_48.
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Thompson, David N., Peter G. Shaw, and Jeffrey A. Lacey. "Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw." In Biotechnology for Fuels and Chemicals. Humana Press, 2003. http://dx.doi.org/10.1007/978-1-4612-0057-4_16.
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Bajare Diana, Bumanis Girts, Korjakins Aleksandrs, and Sele Laura. "Reuse of non-metallic residues from aluminium recycling industry in production of porous building materials." In Construction Materials and Structures. IOS Press, 2014. https://doi.org/10.3233/978-1-61499-466-4-136.
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The aim of this study was to find a new method for usage of the hazardous waste coming from the aluminium scrap recycling factories. It is generally considered that non-metallic residues (NMR) are process waste and subject to disposal after residual metal has been recovered from primary dross. NMR are impurities, which are removed from the molten metal in the process of dross recycling, and it could be defined as a hazardous waste product. Processing of NMR created in the aluminium scrap recycling companies is one of the most challenging tasks due to its toxic nature - in accordance with the Basel Convention, Annex III, marking of this waste is H 4.3 (reaction with water results in highly inflammable substances) and H 10 (reaction with water results in increased concentration of toxic gases, for instance, ammonia). The new alkali activated materials, which could be defined as porous building materials, were created by using calcined illite clay from local site and NMR. Solution of sodium silicate (Na2SiO3+nH2O) modified by commercially available alkali flakes (NaOH) was used as an activating solution. Polymerization mechanism of raw materials in alkaline media was investigated by using FTIR and XRD. Physical and thermal properties of the obtained materials were tested. Density of the obtained materials was in the range 550-675 kg/m3, but the total porosity was from 73 to 78%. The compressive strength of the materials was in range from 1.4 to 2.0 MPa. The thermal conductivity of porous alkali activated building materials was between 0.14 and 0.15 (W/(m&middot;K).
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"The Chemistry, Corrosion and Provenance of Archaeological Glass." In Archaeological Chemistry, 3rd ed. The Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/bk9781782624264-00187.
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Archaeological glass is a non-crystalline solid, predominantly based on a polymerized network of silica tetrahedra modified by alkali and alkaline earth ions. This chapter reviews the Continuous Network Theory for the structure of such materials, and shows how the properties of glass such as working temperatures and chemical durability are explained by this model. In particular, a brief explanation is given of how the colour of glass is controlled not only by the presence of transition metal ions, but also by the interaction between these ions and their position within the network via crystal field theory. Two examples are given of the corrosion of glass, one of atmospheric corrosion, illustrated by some work on the medieval glass in York Minster, and the other considering the more complex situation of the decay of buried archaeological glass. Chemical analysis has resulted in the identification of characteristic chemical patterns over large areas and long time periods, associated with common traditions of use of specific sources of alkali, such as plant ash, evaporite deposits (natron), or ‘forest glass’. As with other common archaeological materials, provenance determination by trace element analysis has been a major objective for many years. For glass this has been largely unsuccessful, but newer isotopic techniques including strontium, neodymium and boron have given new impetus to these enquiries.
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Coppens, Philip. "The Charge Density in Extended Solids." In X-Ray Charge Densities and Chemical Bonding. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195098235.003.0013.
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Extended solids encompass all solids in which no well-defined molecular entities can be distinguished. This is the case for metals and alloys, covalently bonded solids like diamond and silicon, and ionic crystals of which the alkali halides are prototypes. Intermediate cases are common, such as crystals consisting of a charged covalent network with counterbalancing cations or anions. Silicates and their analogues are a prime example of often charged networks with partially covalent bonding. An increasing number of solids are known in which both an extended framework and molecular entities exist, with the molecules being embedded in the extended framework. Graphite intercalation compounds and a variety of host/guest complexes are examples of this class. The bonding features in the charge density are pronounced in crystals with extended covalent networks. The availability of perfect silicon crystals has allowed the measurement of uncommonly accurate structure factors, of millielectron accuracy. The data have served as a test of experimental formalisms for charge density analysis, and at the same time have provided a stringent criterion for quantum-mechanical methods. We will start the discussion in this chapter with silicon and its analogues, diamond and germanium, and proceed with the treatment of silicates, and metallic and ionic crystals. In the face-centered cubic structure of silicon, atoms are located at 1/8 1/8 1/8 and at the center-of-symmetry related position of −1/8 −1/8 −1/8.
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Gioncada, A., P. Fulignati, L. Vezzoli, et al. "Magmatic Sulfides from the Rincón-Portezuelo de las Ánimas Volcanic Complex, Northwest Argentina: Insights on Magma Fertility and Comparison with Mineralized Volcanic Systems." In Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits: A Tribute to Jeremy P. Richards (Volume I). Society of Economic Geologists, 2021. http://dx.doi.org/10.5382/sp24.07.
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Abstract The composition and fate of magmatic sulfides are some of the most critical factors invoked to play a role in the chalcophile metal fertility of arc magmas. Examination of magmatic sulfide accessory minerals in nonmineralized volcanic systems may help to understand the behavior of chalcophile metals at sulfide saturation. This study presents compositional data on magmatic sulfides in lavas of the late Miocene Rincón-Portezuelo de las Ánimas Volcanic Complex, northwest Argentina. This is the easternmost magmatic occurrence in the back arc of the Southern Central Andes, at 27°S, about 75 km northeast from the world-class Bajo de la Alumbrera porphyry Cu-Au deposit. At this latitude the late Miocene volcanic activity migrated eastward as a consequence of the shallowing slab subduction. Both copper-rich and pyrrhotite magmatic sulfide inclusions have been identified in the Rincón-Portezuelo de las Ánimas volcanic suite, straddling the high K calc-alkaline–shoshonite boundary. We discuss the sulfide composition in the framework of magmatic evolution and in comparison to the metal content of magmatic sulfides of the coeval Farallón Negro Volcanic Complex, associated with the Bajo de la Alumbrera porphyry Cu-Au and other mineralized systems. The results show that sulfide liquid, exsolved from silicate melts of intermediate composition, stores Cu, Pb, Ag, and Bi in crystal mushes, reducing the mineralizing potential of residual melts while fertilizing the middle-upper crust. Gold behavior seems to be controlled by additional mechanisms, linked to the magma source or to an early partitioning into an S-bearing fluid phase. The high Au/Cu ratio of sulfides formed as monosulfide solid solution may be associated with the potassic character of the magmas in this sector of the Central Andes.
Conference papers on the topic "Alkali metal silicate"
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Lytle, Darren A., Michael R. Schock, and Thomas J. Sorg. "Investigation on Techniques and Control of Building Lead and Copper Corrosion by Orthophosphate and Silicate." In CORROSION 1995. NACE International, 1995. https://doi.org/10.5006/c1995-95609.
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Abstract A new building was identified as having high lead levels in it’s drinking water. Through a detailed sampling protocol, the sources of lead were identified as brass plumbing fittings and fixtures, and Sn:Pb solder. A study was performed in two isolated sections of the building plumbing system to determine if the lead levels could be reduced naturally with time by simply using the water. Significant reductions in lead levels were not achieved following 8 months of water usage. A second study was performed to evaluate the effectiveness of three chemical corrosion inhibitors; zinc orthophosphate, alkali metal orthophosphate, and sodium silicate, to reduce the lead levels. Three economic, simple, low maintenance chemical feed systems were designed and installed in three different isolated sections of the building’s plumbing system. The chemicals were fed into the building sections for approximately 4 months. Results showed that all inhibitors effectively and rapidly reduced lead and copper levels.
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Morefield, Sean W., Charles A. Weiss, Philip G. Malone, and Mike Koenigstein. "Reactive Silicate Coatings for Protecting and Bonding Reinforcing Steel in Cement-Based Composites." In CORROSION 2009. NACE International, 2009. https://doi.org/10.5006/c2009-09492.
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Abstract Engineered glass-ceramic coatings that contain hydraulically reactive calcium silicates have been shown to be remarkably effective in increasing the bond strength between reinforcing steel and the surrounding concrete or mortar. The coatings are a mixture of portland cement and alkaline-resistant basecoat glass enamel. X-ray diffraction patterns indicate that all of the major reactive compounds, such as dicalcium silicate and tricalcium silicate and the ferrites and even gypsum survived the firing of the frit-cement mixture onto steel. When exposed to water the cement grains in contact with water hydrated to form gel products similar to those produced in hydrating normal cement paste. The hydration of the layer of cement appears to remove the “wall effect” and the bond strength between the concrete and steel is increased up to four times that developed with uncoated steel. The enamel over the steel isolates the metal and produces durable corrosion protection. A SEM study of cracks purposely produced in the enamel indicates the embedded cement grains will hydrate when moisture contacts them and produce hydration products that can fill fractures and raise the pH at the steel surface.
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Pomeroy, M. J., P. Byrne, and R. Ramesh. "Oxidation and Alkali-Metal Sulphate Corrosion Processes in Silicon Nitride - Based Materials." In CORROSION 1998. NACE International, 1998. https://doi.org/10.5006/c1998-98198.
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Abstract β-sialon materials (Si(6-z)AlzOzN(8-z)) densified with a YSiAlON glass and having z-values of 0.2, 0.5, 1.0, 1.5, 2.0 and 3.0 have been subjected to oxidation and hot corrosion experiments. From the results obtained, the process by which oxidation occurs at a temperature of 1350°C involves direct solution of β-sialon grains by an aluminosilicate liquid. This liquid forms by the preferential diffusion of yttrium and/or aluminium from the bulk of the ceramic into the scale - ceramic interface. In the case of higher z-value materials (≥1.0), liquid formation is also facilitated by the reaction of yttrium aluminium garnet, formed by the devitrification of the YSiAlON glass during oxidation, and silica formed as an oxidation product. Hot corrosion experiments carried out using a crucible testing technique at 1150°C showed that only the z=0.2 and 3.0 materials do not undergo catastrophic corrosion by molten sodium, potassium sulphate. The z=0.2 material is partially protected by a high viscosity surface film, whilst the z=3.0 material is protected by the formation of a nepheline (RAlSiO4 [R= alkali - metal]) scale layer. Corrosion morphologies for these two materials show that the reaction interface is at the scale - ceramic interface and that a liquid phase is in direct contact with the ceramic. Accordingly, the mechanism by which hot corrosion occurs, like oxidation at the higher temperature, is by solution of β-silaon grains. Whilst the z=3.0 material is protected by the formation of nepheline, the five to six fold difference between the coefficients of thermal expansion for this phase and the z=3.0 material results in significant mechanical damage to the scale during thermal cycling. Accordingly, the nepheline phase may have only limited protective ability.
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Sousa, I., A. Kuznetsova, T. Galvão, et al. "The Use of Nanostructured Materials Loaded with pH Indicating Molecules for Corrosion Sensing." In CORROSION 2017. NACE International, 2017. https://doi.org/10.5006/c2017-09666.
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Abstract In this work we report the synthesis of different materials for immobilization of well-known pH indicators, to be used as additives in coatings for corrosion sensing: inorganic materials such as layered double hydroxides, silica nanocapsules and polymeric microcapsules (chitosan). The materials obtained were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopies. Furthermore, the release profile of the obtained materials was performed using UV-Visible spectrophotometry under conditions relevant for the onset of corrosion processes, namely in the presence of NaCl and different pH conditions. The release and color changes were correlated with pH maps obtained by the scanning ion-selective technique for different galvanic couples (Al-Cu, Fe-Zn) and magnesium alloy AZ31. The results show that the materials obtained are able to change color, associated with the pKa of selected indicators and ascribed to pH changes in the alkaline direction as result of cathodic activity in different metals. These findings open prospects for the use of the prepared additives in functional coatings for corrosion sensing.
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N, Ajmal S., Thushara Raju, and Ramaswamy K. P. "Numerical Evaluation of Alkali Activated Reinforced Geopolymer Concrete Column." In 6th International Conference on Modeling and Simulation in Civil Engineering. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.156.12.
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Geopolymer concrete is a type of concrete that is made by reacting aluminate and silicate-bearing materials such as fly ash or slag from iron and metal production with a caustic activator. It can be a suitable substitute for ordinary Portland cement (OPC) concrete. Geopolymer concrete is considered as green concrete since the reduced CO2 emission and due to the usage of waste materials for manufacturing. A lot of studies are undertaken in the field of the usage of geopolymer concrete in structural members such as beams, columns, slabs, etc. In this paper, geopolymer concrete columns are modeled using the Finite Element Modeling software ANSYS, and the behavior of the same column under axial loading and eccentric loading is studied. The axial behavior of the geopolymer concrete column is compared with the axial behavior of the conventional M30 concrete column and also the behavior of the geopolymer concrete column under axial load is compared with that of 50mm eccentric load.
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S, Reshma, Chinsu Mereena Joy, Thushara Raju, and Ramaswamy K. P. "Numerical Study on Flexural Behavior of Alkali-Activated Slag Concrete Beam by ANSYS." In 6th International Conference on Modeling and Simulation in Civil Engineering. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.156.14.
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Geopolymer concrete is a type of concrete that is made by reacting aluminate and silicate-bearing materials with a caustic activator, such as fly ash or slag from iron and metal production. It can be a suitable substitute for ordinary Portland cement (OPC). Geopolymer concrete is considered green concrete because of the reduced CO2 emission and due to the usage of waste materials for manufacturing. Several investigations are happening on the topic of geopolymer concrete in structural members like beams, columns and slabs. This work focuses on the numerical analysis of the flexural behaviour of alkali-activated reinforced slag concrete beam under cyclic loading. Numerical study was conducted using finite element tool, ANSYS. For this, a numerical model was developed and modeled. Thereafter, cyclic load was applied on the same beam to obtain the load-deformation curve. From this curve, the first crack load, ultimate load, maximum deformation, ductility index and energy absorption capacity were obtained.
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Ward, John, Muhammad Akram, and Roy Garwood. "Fluidised Bed Combustion of Blends of Coal and Pressed Sugar Beet Pulp." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44093.
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It can be difficult to burn relatively cheap, poor quality, unprepared biomass materials in industrial heating processes because of their variable composition, relatively low calorific values and high moisture contents. Consequently the stability and efficiency of the combustion process can be adversely affected unless they are co-fired with a hydrocarbon support fuel. There is a lack of information on the “optimum” conditions for co-firing of coal and high moisture biomass as well as on the proportions of support fuel which should be used. This paper is therefore concerned with the pilot scale (<25 kW thermal input) fluidised bed combustion of blends of coal with pressed sugar beet pulp, a solid biomass with an average moisture content of 71%. The experimental work was undertaken in collaboration with British Sugar plc who operate a coal-fired 40 MW thermal capacity fluidised bed producing hot combustion gases for subsequent drying applications. The project studied the combustion characteristics of different coal and pressed pulp blends over a wide range of operating conditions. It was found that stable combustion could only be maintained if the proportion of pulp by mass in the blended fuel was no greater than 50%. However evaporation of the moisture in the pressed pulp cools the bed so that the excess air which is necessary to maintain a specified bed temperature at a fixed thermal input can be reduced as the proportion of biomass in the blended fuel is increased. Therefore, with a 50/50 blend the bed can be operated with 20% less fluidising air and this will be beneficial for the output of the full scale plant since at present the flow rate of the air and hence the amount of coal which can be burnt is restricted by supply system pressure drop limitations. A further benefit of co-firing pressed pulp is that NOx emissions are reduced by about 25%. Agglomeration of the bed can be a problem when co-firing biomass because of the formation of “sticky” low melting point alkali metal silicate eutectics which result in subsequent adhesion of the ash and sand particles. Consequently longer term co-firing tests with a 50/50 blended fuel by mass were undertaken. Problems of bed agglomeration were not observed under these conditions with relatively low levels of alkali metals in the ash.
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Maulidin, I., K. Nakashima, R. Naota, C. Takano, and S. Kawasaki. "Silica and polyphenol-based adsorbents of heavy metals fabricated by enzymes." In International Symposium on Earth Resources Management & Environment - ISERME 2024. Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024. https://doi.org/10.31705/iserme.2024.44.
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Lead (Pb) contamination in water sources poses severe health risks to both humans and ecosystems. Conventional methods for Pb removal often rely on chemical treatments or expensive filtration systems, which can be economically burdensome and environmentally hazardous. In response to this pressing issue, this study presents a novel approach leveraging biologically inspired fabrication techniques by using enzymes for the development of an efficient and ecofriendly silica-based biosorbent incorporating poly-tannic acid for efficient Pb (II) ion removal from aqueous solutions. The process involves the biological immobilization of laccase enzyme on the bead’s surface via a protective silica layer formed by the functional silica-polymerizing enzyme, silicatein. Silica beads were chosen as the support material for enzyme immobilization due to their favourable chemical and physical properties and natural compatibility with the silicatein enzyme. This innovative method prevents the immobilized enzyme from leaching and enhances laccase immobilization on the beads, ensuring the enzyme thermostability, and maintains its activity even under harsh conditions such as at an acidic-alkaline pH. Furthermore, poly-tannic acid was formed on the bead surface through oxidative polymerization mediated by immobilized laccase. Successful coverage of poly-tannic acid polymerized by laccase on the beads was confirmed by using SEM-EDS and FTIR spectra. The silicatein-treated biosorbent exhibited high laccase loading capacity and retained about 48% of its initial activity when tested under alkaline conditions. Additionally, it showed a remarkable enhancement compared to the biosorbent treated without silicatein in activity across varying temperatures which indicated favourable thermostability properties. The silicatein-treated biosorbent revealed its effectiveness in removing Pb(II) ions from aqueous solutions with a maximum adsorption capacity of 52.4 mg/g, a threefold increase compared to that of the biosorbent without silicatein. This silica-based biohybrid material presents advantages over conventional methods, including higher adsorption capacity and enhanced stability, offering a promising environmentally friendly solution for heavy metal bioremediation in water sources.
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Krumrine, Paul Henry, Michael Lefenfeld, and Gregory A. Romney. "Investigation of Post CHOPS Enhanced Oil Recovery of Alkali Metal Silicide Technology." In SPE Heavy Oil Conference-Canada. Society of Petroleum Engineers, 2014. http://dx.doi.org/10.2118/170141-ms.
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Вайтнер, В. В., and А. Н. Габдуллин. "NITRIC ACID METHOD FOR PROCESSING HIGH-SILICON ALUMINA-CONTAINING RAW MATERIALS." In Инновации и «зелёные» технологии : IV Всероссийская научно-практическая конференция. Crossref, 2024. http://dx.doi.org/10.34830/sounb-conf.2023.24.99.006.
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В статье рассмотрен азотнокислотный способ переработки вскрышной породы угледобычи – аргиллита Волчанского месторождения. В составе сырья содержится 52,6% кремнезема и 23,3 % глинозема, что позволяет считать глинозем высококремнистым сырьем. Предварительно прокаленный аргиллит выщелачивали азотной кислотой, с последующим обезжелезиванием нитратных растворов. Полученную кристаллическую массу подвергали термическому гидролизу, в ходе которого происходит регенерация азотной кислоты. После отмывания от нитратов щелочных и щелочно-земельных металлов получен глинозем, который может быть использован для производства керамики и огнеупоров. The article discusses the nitric acid method of processing overburden rock from coal mining – mudstone of the Volchanskoe deposit. The raw material contains 52.6% silica and 23.3% alumina, which allows us to consider alumina as a high-silica raw material. Pre-calcined mudstone was leached with nitric acid, followed by deferrization of nitrate solutions. The resulting crystalline mass was subjected to thermal hydrolysis, during which nitric acid was regenerated. After washing from alkali and alkaline earth metals nitrates, alumina is obtained, which can be used for the production of ceramics and refractories.
Reports on the topic "Alkali metal silicate"
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Chirachanchai, Suwabun. A Novel ion extraction material derived from silica surface modified silybenzoxazine derivatives via host-guest properties. Chulalongkorn University, 2001. https://doi.org/10.58837/chula.res.2001.81.
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Silylbenzoxazine derivatives with different bulky group on benzene ring are synthesized employing aminosilane as a primary amine. The silylbenzoxazine derivatives with more bulky group exhibit low ion extraction percentage due to the difficulty of molecular assembly formation as a result of the bulky group repulsion combining with the long alkyl chain of silane. Silica surface modified benzoxazines are successfully achieved via silylbenzoxazine derivatives and show the ion extraction property for various alkali and alkaline earth metal ions. When silane is coupled onto silica, the benzoxazine shows different ion extraction ability from that of silylbenzoxazine. The silica surface modified silylbenzoxazines with bulky groups exhibit high ion extraction percentage which may be due to the loose packing structure of the molecular assembly inducing the high amount of cavity for guest.