10193-36-9Relevant articles and documents
Structural and Photoluminescence properties of nepheline-structure NaAlSiO4:Dy3+ nanophosphors
Kumar, Ashwini,Dhoble,Peshwe,Bhatt, Jatin
, p. 100 - 106 (2014)
Most of the phosphors are composed of known host material with the incorporation of some percentage of an activator into the matrix. In this work Dy3+-activated NaAlSiO4 phosphors have been synthesized using sol-gel combustion techni
Controlled growth of in situ silica in a NR/CR blend by a solution sol-gel method and the studies of its composite properties
Bansod, Naresh D.,Kapgate, Bharat P.,Das, Chayan,Basu, Debdipta,Debnath, Subhas Chandra,Roy, Kumarjyoti,Wiessner, Sven
, p. 53559 - 53568 (2015)
Silica is grown in situ into a natural rubber (NR)/chloroprene rubber (CR) blend (at 40/60 ratio), by a solution sol-gel method, where the silica content in rubber blend is increased in a controlled manner exceeding the limit found for the same blend ratio in the soaking sol-gel method. Reaction conditions have been optimized to get adequate conversion of tetraethoxysilane (TEOS, a silica precursor) to silica. Rheological, thermal, mechanical and viscoelastic properties of all the composites are compared with those of the unfilled rubber blend at similar conditions. Thermal and mechanical properties of the composites are found to improve consistently as silica content in the composite increases owing to increased rubber-filler interaction as revealed in dynamical mechanical analysis (DMA). Further improvement in the properties is observed for a particular composite where a silane coupling agent ((γ-aminopropyl)trimethoxysilane, γ-APS) is used in the reactive sol-gel system during in situ generation of silica. This is attributed to the uniform distribution of silica in the rubber matrix and strong rubber-filler interaction, caused by bifunctionality of silane, as revealed by morphology and DMA studies respectively. The reinforcement effect of silica is evaluated by comparing the experimental results with theoretical values obtained from the Guth-Gold model and the modified Guth model. The present study supplements the in situ silica generation in NR/CR blend of 40/60 ratio, following the solution sol-gel method, to the earlier study involving the soaking sol-gel method where the maximum reinforcement was found for this composition.
Influence of annealing temperature on structural and optical properties of SiO2:RE2O3 [RE = Y, Gd] powder
Ahlawat, Rachna
, p. 356 - 363 (2015)
SiO2:RE2O3 [RE = Y, Gd] powder were prepared by wet chemical technique and the prepared binary oxides annealed at 500 °C and 900 °C. The crystalline structure, phase transformation, and surface morphologies of as-prepared and annealed samples were investigated by XRD and TEM. The normal transmission was measured using FTIR spectroscopy. Optical properties have been studied with UV-Vis spectroscopy and PL study. XRD results shows that the as prepared samples of SiO2:RE2O3 [RE = Y, Gd] powder has mixed phases of RE(NO3)3 and Si(OH)3. However, cubic rare earth oxide phase alone is found for annealed samples. The strain values are calculated from W-H plot for annealed samples. TEM micrograph shows that the samples are composed of individual spherical nanocrystallites at 500 °C and aggregated nanocrystallites at 900 °C. From the UV-Vis spectra, it is found that the position of the absorption peak is shifted toward the higher wavelength side when annealing temperature is increased. In the PL spectra, the broad emission bands are observed between 570-600 nm and the presence of O-Si-O (silica) and metal oxide is confirmed by FTIR spectra.
Interactions of water vapor with oxides at elevated temperatures
Jacobson, Nathan,Myers, Dwight,Opila, Elizabeth,Copland, Evan
, p. 471 - 478 (2005)
Many volatile metal hydroxides form by reaction of the corresponding metal oxide with water vapor. These reactions are important in a number of high temperature corrosion processes. Experimental methods for studying the thermodynamics of metal hydroxides include: gas leak Knudsen cell mass spectrometry, free jet sampling mass spectrometry, transpiration and hydrogen-oxygen flame studies. The available experimental information is reviewed and the most stable metal hydroxide species are correlated with position in the periodic table. Current studies in our laboratory on the Si-O-H system are discussed.
Near-infrared spectroscopic study of [AlO4Al12(OH)23(H2O)12]7+-O-Si(OH)3 nitrate crystals formed by forced hydrolysis of Al3+ in the presence of TEOS.
Kloprogge,Ruan,Frost
, p. 2405 - 2411 (2000)
The polymer [AlO4Al12(OH)23(H2O)12]7+-O-Si(OH)3 was prepared by forced hydrolysis of Al3+ up to an OH/Al molar ratio of 2.0 in the presence of monomeric orthosilicic acid. Crystalline material was obtained by slow evaporation. Although the near-infrared spectra of the Al13-sulfate and Al13-O-Si(OH)3 are very similar, there are differences related to the bonding of the -O-Si(OH)3 group to the Al13-unit. The strong complex of bands around 7000 cm(-1) associated with the overtones and combination bands of the OH-stretching modes for Al13-sulfate is much weaker for Al13-O-Si(OH)3 and the opposite is true for the complex of bands around 5000 cm(-1) associated with the water overtone and combination modes, suggesting that the outer OH-groups of the Al13-unit are involved in the formation of the new Al13-O-Si(OH)3 units. A weak band around 7370-7631 cm(-1) is interpreted as the overtone of the Si-OH stretching vibration around 3740 cm(-1). A low intensity band, absent for Al13-sulfate and -nitrate is observed around 5550-5570 cm(-1) and is interpreted as the overtone of the OH-stretching mode of the OH-groups in the vicinity of the central AlO4 in the Al13-unit around 2890-2935 cm(-1). The interaction between the -O-Si(OH)3 group and the Al13-unit has a small influence on other bands like the combination modes of water in the 4400-4800 cm(-1) region, which show a small shift towards higher wavenumbers. The internal OH-groups in the Al13-complex are relatively shielded by the water molecules and therefore do not reflect the influence of the -O-Si(OH)3 in their band positions.
Effect of polyethylenimine on hydrolysis and dispersion properties of aqueous Si3N4 suspensions
Zhu, Xinwen,Uchikoshi, Tetsuo,Suzuki, Tohru S.,Sakka, Yoshio
, p. 797 - 804 (2007)
The roles of polyethylenimine (PEI) in the hydrolysis and dispersion properties of aqueous Si3-N4 suspensions were studied in terms of the hydrolysis, adsorption, electrokinetic, and rheological measurements. It was found that the pH change of the suspensions in the acidic environment could be minimized in the presence of ≥ 0.5 dwb% PEI. The ammonia and oxygen measurements suggest that this phenomenon is primarily attributed to the buffer mechanism generated by the ionized PEI, instead of the protection mechanism. The constant pH enables the suspensions to retain a better stability with time at acidic pH. The adsorption of PEI on Si3N4 is a high-affinity type at highly basic pH, but is a low-affinity type at acidic pH. As the PEI amount increases, the adsorption shifts the isoelectric point (IEP) of Si3N4 from pH 5.9 to pH ～11 until complete coverage is attained. The stability of Si3N4 suspensions is found to depend strongly on the saturated adsorption of PEI, which is as a function of the pH and PEI amount. Once the saturated adsorption limit is reached, the excess free PEI molecules become more detrimental to the stability with increased solid loading. The stabilization mechanisms of Si 3N4 suspensions by PEI were discussed in detail.
Mass spectrometric identification of Si-O-H(g) species from the reaction of silica with water vapor at atmospheric pressure
Opila, Elizabeth J.,Fox, Dennis S.,Jacobson, Nathan S.
, p. 1009 - 1012 (1997)
A high-pressure sampling mass spectrometer was used to detect the volatile species formed from SiO2 at temperatures between 1200° and 1400°C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH)4. The fragment ion Si(OH)3+ was observed in quantities 3 to 5 times larger than the parent ion Si(OH)4+. The Si(OH)3+ intensity was found to have a small temperature dependence and to increase with the water vapor partial pressure as expected. In addition, SiO(OH)+, believed to be a fragment of SiO(OH)2, was observed. These mass spectral results were compared to the behavior of silicon halides.
Preparation and luminescence property of red-emitting hardystonite phosphors by near-ultraviolet irradiation
Yao, Shanshan,Xue, Lihong,Yan, Youwei,Yan, Mifang
, p. 1477 - 1482 (2011)
A1.95ZnSi2O7:Eu0.05 3+ (A=Ca, Sr, Ba) red phosphors were prepared by combustion-assisted synthesis method and their efficient red emission under near ultraviolet (UV) were observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometer, respectively. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0→7F2 transition of Eu3+. These phosphors have two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively. Thus, these phosphors could be used as red components for white light-emitting diodes.
Sonochemical synthesis of silica and silica sulfuric acid nanoparticles from rice husk ash: A new and recyclable catalyst for the acetylation of alcohols and phenols under heterogeneous conditions
Salavati-Niasari, Masoud,Javidi, Jaber
, p. 705 - 712 (2012)
Silica nanoparticles were synthesized from rice husk ash at room temperature by sonochemical method. The feeding rate of percipiteting agent and time of sonication were investigated. The nanostructure of the synthesized powder was realized by the FE-SEM photomicrograph, FT-IR spectroscopy, XRD and XRF analyses. These analytical observations have revealed that the nano-sized amorphous silica particles are formed and they are spheroidal in shape. The average particle size of the silica powders is found to be around 50 nm. The as-synthesized silica nanoparticles were subsequently modified with chlorosulfonic acid and prepared silica sulfuric acid nanoparticles, which were employed as an efficient catalyst for the acylation of alcohols and phenols with acetic anhydride in excellent yields under solvent-free conditions at room temperature. This reported method is simple, mild, and environmentally viable and catalyst can be simply recovered and reused over 9 times without any significant loss of its catalytic activity.
Forbes,Anderson
, p. 1241 (1947)
Poly(γ-glutamic acid)/silica hybrids with calcium incorporated in the silica network by use of a calcium alkoxide precursor
Poologasundarampillai, Gowsihan,Yu, Bobo,Tsigkou, Olga,Wang, Daming,Romer, Frederik,Bhakhri, Vineet,Giuliani, Finn,Stevens, Molly M.,McPhail, David S.,Smith, Mark E.,Hanna, John V.,Jones, Julian R.
, p. 8149 - 8160 (2014)
Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation. Sol-gel hybrids have the potential to do this through their nanoscale interpenetrating networks (IPN) of inorganic and organic components. Poly(γ-glutamic acid) (γ-PGA) was introduced into the sol-gel process to produce a hybrid of γ-PGA and bioactive silica. Calcium is an important element for bone regeneration but calcium sources that are used traditionally in the sol-gel process, such as Ca salts, do not allow Ca incorporation into the silicate network during low-temperature processing. The hypothesis for this study was that using calcium methoxyethoxide (CME) as the Ca source would allow Ca incorporation into the silicate component of the hybrid at room temperature. The produced hybrids would have improved mechanical properties and controlled degradation compared with hybrids of calcium chloride (CaCl2), in which the Ca is not incorporated into the silicate network. Class II hybrids, with covalent bonds between the inorganic and organic species, were synthesised by using organosilane. Calcium incorporation in both the organic and inorganic IPNs of the hybrid was improved when CME was used. This was clearly observed by using FTIR and solid-state NMR spectroscopy, which showed ionic cross-linking of γ-PGA by Ca and a lower degree of condensation of the Si species compared with the hybrids made with CaCl 2 as the Ca source. The ionic cross-linking of γ-PGA by Ca resulted in excellent compressive strength and reduced elastic modulus as measured by compressive testing and nanoindentation, respectively. All hybrids showed bioactivity as hydroxyapatite (HA) was formed after immersion in simulated body fluid (SBF). Organic/inorganic hybrid materials: Calcium methoxyethoxide (CME) was found to be an effective precursor for successfully introducing calcium into organic/inorganic hybrid materials (see figure). The Ca2+ ions were found to successfully cross-link the polymer chains, thereby avoiding a burst release of polymer and Ca2+ in buffered media. CME was found to distribute within the inorganic silica network thanks to the high reactivity of CME with hydroxyl groups.
Silanol Compound, Composition, and Method for Producing Silanol Compound
-
Paragraph 0242; 0243, (2017/07/14)
The purpose of the present invention is to provide silanol compounds that can be used as raw materials of siloxane compounds and the like, and a composition of the silanol compounds, as well as to provide a production method that makes it possible to produce silanol compounds at excellent yield. A composition comprising 5 mass % to 100 mass % of a silanol compound represented by Formulas (A) to (C) can be prepared by devising to produce silanol compounds under water-free conditions, to produce silanol compounds in a solvent having the effect of suppressing the condensation of silanol compounds, and to perform other such processes, the composition being able to be used as a raw material or the like of siloxane compounds because the silanol compounds can be stably present in the resulting composition.
