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Showing 1 to 20 of 404 for “"sol-gel"”.
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The sol-gel polymerization of octamethoxysilsesquioxane
In order to understand the effect of various solvents and catalysts on the sol-gel polymerization of [SigOi2](OCHg)g, the polymerization was followed by 29Si NMR spectroscopy, which indicated that the cubic structure of [SigOi2](OCH3)g was retained under initial polymerization conditions. …
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Sol-gel preparation of silicon nitride materials
Sol-gel techniques are mainly used for oxides but are of growing interest for non-oxide materials. They allow formation of solid materials through gelation of precursor solutions and can be used to control composition and to produce a large number of useful morphologies such as films, monoliths, …
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Multinuclear NMR Investigations of Sol-Gel Systems
… and polymerization of metal alkoxides in solution to form a gel, which may then be fired to form a glass. This so-called sol-gel process represents the synthesis of an inorganic polymer in a manner analogous to that in which organic polymers have traditionally been prepared.
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Strengthening of glass by sol-gel coatings
Thesis. (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1988.
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Sol-gel derived tantalum oxide thin films
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.
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Molecular growth pathways in silica sol-gel polymerization
… polysilicate intermediates formed during silica sol-gel polymerization. This protocol allowed the structural identification of mono- through hexasilicate species (1<x<6 in [SixOy]9OCH3)a) formed during partial hydrolysis and condensation of tetramethylorthosilicate.
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Herstellung und Charakterisierung carbonsäuremodifizierter Sol-Gel-Vorstufen von Mullit
Nach dem Sol-Gel-Verfahren wurden carbonsäuremodifizierte Mullitvorstufen hergestellt und charakterisiert. Dabei wurde die Kettenlänge der zur Synthese der Sole verwendeten Carbonsäuren variiert. Es zeigte sich, dass die säurekatalysierte Kondensation der Siliciumkomponente zu linearen, oligomeren …
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Pyrolyse- und Sinterverhalten Sol-Gel-abgeleiteter Al2O3-YAG-Fasern
Nichtwäßrige Sol-Gel-Vorstufen, die zu einem Mischgefüge aus Al2O3 und YAG führen (Volumenverhältnis 45 : 55), wurden zu Fasern versponnen, in unterschiedlichen Atmosphären pyrolysiert und abschließend gesintert. Die strukturelle Ent-wicklung während der Pyrolyse der Gel-Fasern wurde in …
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Polyoxotitanates and their role in titania sol-gel polymerization
… crystal X-ray diffraction study of its t-BuOH solvate revealed a $\rm Ti\sb{18}O\sb{45}$ metal-oxygen framework having a pentacapped Keggin structure Reaction of the complex with t-amyl alcohol led to the product $\rm\lbrack Ti\sb{18}O\sb{28}H\rbrack (OBu\sp{t})\sb{12}(OAm\sp{t})\sb5$, …
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Sol-gel synthesis of one-dimensional photonic bandgap structures
… using SiO2 and TiO2 films deposited from solution by the sol-gel method. A dielectric mirror, or broadband interference filter, was fabricated by alternating quarter-wave optical thickness layers of the two films on a silicon substrate for a total of six layer pairs. This device exhibited …
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Structure-property behavior of sol-gel derived hybrid materials
… were carried out on a number of different hybrid sol·gel materials. Multifunctional silicon ethoxides were prepared and studied by solid state ²⁹Si NMR and Raman spectroscopy to determine the type of silicate structures formed and the degree of conversion attained by the sol-gel process under …
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Raman studies of the nanostructure of sol-gel materials
Four sol-gel systems (alumina, aluminum hydroxide, zirconia, and magnesia) were investigated, primarily by laser spectroscopy, on several series of materials prepared by systematically varying the synthesis procedures. Key material phases analyzed were: (1) nanocrystalline boehmite [AlO(OH)]; (2) …
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Siloxane modified hybrid materials by the sol-gel process
… to the fonnation of a hybrid material by the sol-gel process. The oligomeric species chosen was silanol terminated poly(dimethylsiloxane) (PDMS) and the inorganic oxide precursor chosen was titanium tetra-isopropoxide (TIP). The rationale for choosing these materials stemmed from the desire to …
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Characterization of Methyltrimethoxysilane Sol-Gel Polymerization and the Resulting Aerogels.
… of these materials appears to affect their gelation behaviors and impact their mechanical properties and shrinkage during processing. 29Si solution NMR was used to follow the structural evolution of MTMS (methyltrimethoxysilane) polymerization to gelation or precipitation, and thus to better …
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The sol-gel synthesis of anti-stokes luminescent glass materials
… The synthesis of silica based glasses using sol-gel techniques is covered thoroughly in this work and the incorporation of various cations into these matrices has been investigated. Amongst the cations added to silica sol-gel reactions are titania, alumina and yttrium. Their reactions and the …
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Investigations of the early stages of titania sol-gel processing
… (OPr$\sp{\rm i})\sb{18}$ as the sole product in solution. Reaction of Ti(OPr$\sp{\rm i})\sb4$ with one equivalent of water in isopropanol at 100$\sp\circ$C for 3 days yielded as the sole products a 1:1 mixture of two isomeric complexes, $\alpha\sb1$- (Ti$\sb{12}$O$\sb{16}$) …
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Sol-gel processing of RxY3-xAlyFe5-yO12 magneto-optical films
… Accomplishment of this task was achieved via sol-gel processing of rare-earth and aluminum substituted yttrium-iron garnet (RxY3-xAlyFe5-yO12, R,Al:YIG), where R= Bi, Gd, Er, Ho. Detailed are the processing conditions, parameters and results leading to R,Al:YIG films with MO response. Success …
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