Papers by Keyword: Sol-Gel Synthesis

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Authors: Alexandre A. Ivanov, Vasily I. Tuev, Anatoly A. Vilisov
Abstract: The sol-gel synthesis of filled aluminosilicates (FAS) has been developed. Such FAS consist of dendrimer morphology macromolecules capable to accommodate as a filler up to 70 % wt of high-refractory nitrides and oxides of high-melting compounds. The study of the obtained ceramic coatings on the developed metal surfaces has showed their use prospects to develop an ion beam control electrode in the ion plasma machine, microelectronics, and LED technology.
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Authors: Oksana Lebedeva, Yury Pozhidaev, Evgenya Sipkina, Alexandra Chesnokova, Nikolay Ivanov
Abstract: The copolymers of N-vinylpyrazole with vinyl chloride and methyl methacrylate were obtained by radical polymerization. Constants reactivity and microstructure parameters of copolymers were calculated and their properties were studied. The sol-gel synthesis of obtained copolymers with tetraethyl orthosilicate results in a hybrid organic-inorganic composites. Films with proton conductivity to 7.8·10-3 S·sm-1 were formed on the basis the copolymers and composites.
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Authors: Chun Yuan Huang, Ping Hua Tsai, Ying Chih Chen, Hsin Chieh Yu, Yan Kuin Su
Abstract: In this article, the quantum dot (QD) light emitting diodes (QDLEDs) with ZnO electron transport layer (ETL) and MoO3 hole transport layer (HTL) were demonstrated. The ZnO ETL was fabricated by sol-gel method. To achieve balanced electron and hole injection, hole transport materials including 4,4'-di(N-carbazolyl)biphenyl (CBP) and MoO3 were also adapted. The device structure can be simply depicted as indium tin oxide (ITO)/ZnO/Cs2CO3/QD/CBP/MoO3/Au. It was found that the Cs2CO3 played an important role to facilitate radiative recombination and reduce the leakage current due to the poor quality of sol-gel fabricated ZnO thin film. Via inserting an annealed Cs2CO3 buffer layer with proper thickness, red-emitting QDLEDs with low luminance turn-on voltage of 4.1 V and luminance larger than 100 cd/m2 could be obtained. With our demonstration, QDLEDs with ZnO ETL can be a promising device structure for realizing QDLED’s commerizing.
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Authors: Félix Galindo-Hernández, Ricardo Gómez
Abstract: Sol-gel TiO2 and TiO2–CeO2 materials were synthesized at pH3 using HNO3 as hydrolysis catalysts. Gels were annealed at 473, 673 and 873 K for 4h. X-ray diffraction Rietveld refinement was used to determine the mean crystallite size, TiO2 stoichiometry (titanium deficiency) and Fourier electronic density maps. It has been found that the fractal surface dimension diminishes on TiO2 a nd TiO2–CeO2 surfaces as the annealing temperature increases. The X-ray diffraction patterns showed nanocrystalline anatase phase in the range of 8.9 to 43.6 nm in depending of the annealing temperature. A dependency between the crystallite size and the titanium deficiency [V+Ti4+] per unit cell was found, as lowest is the crystallite highest is the titanium deficiency. Strong differences on the Fourier electron density map were found on TiO2 and TiO2–CeO2 materials. It was concluded that the sol-gel preparation method favors the formation of nanosized TiO2 with high Ti4+ stoichiometry deficiency.
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Authors: S.V. Trukhanov, A.V. Trukhanov, Christian E. Botez, H. Szymczak
Abstract: Nanocrystalline La0.50Ba0.50MnO3 manganite was synthesized by an optimized sol-gel method. The initial sample was subjected to step-by-step heat treatment under air atmosphere. The ion stoichiometry, the morphology of crystallites of ceramics, and the magnetic properties were studied. It is established that the average crystallite size increases with increasing annealing temperature. All of the samples studied are characterized by a perovskite-like cubic structure, with the unit cell parameter a increasing continuously with the average crystallite size. The most significant lattice compression occurs in the sample with an average crystallite size of ~ 30 nm. The increase in the average crystallite size causes a nonmonotonic increase in the Curie temperature and in the spontaneous magnetic moment. The anomalous behavior of the magnetic properties of the La0.50Ba0.50MnO3 manganites obtained is explained by the competition between two size effects, namely, the frustration of the indirect exchange interactions Mn3+ – O – Mn4+ on the nanocrystallite surface and the crystal lattice compression due to the crystallite surface tension.
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Authors: Ben Lan Lin, Sheng Cui, Xiao Dong Shen, Ying Li Leng, Xue Yong Liu, Yu Liu
Abstract: Silica-based aerogels doped with nano-ITO powder were synthesized using sol–gel process followed by supercritical drying. The main factors were studied including dosage of compling agent KH570 and ITO. The result shows that thermal radiation conductivity is 0.02659 W/(m•K) with ITO of 44.44% after 10 g ITO powder is modified with 1 mL KH570. The microstructure and physical characteristic of the SiO2–ITO aerogels were characterized by FTIR, SEM, TG-DSC and BET. Their specific surface was in the range of 513–775m2/g and their average pore size was mainly 20 nm. Nano-ITO powders are physically embedded by SiO2 aerogels.
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Authors: Opeyemi Adetola, Leonid Golovko, Aleksey Vasiliev
Abstract: Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using the sol-gel technique. The effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were somewhat lower compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 500-1100 nm except for the W-containing sample obtained with trimethylstearylammonium chloride, which was significantly lower. This unusual effect was attributed to stabilization of primary silica nanoparticles by interactions between the surfactant and HPA. High ratio HPA/TEOS resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing HPAs in mesoporous structure.
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Authors: Lorraine Raboin, Muriel Matheron, Thierry Gacoin, Jean Pierre Boilot
Abstract: Well-ordered organosilicate mesoporous coatings with the 3D-hexagonal symmetry are prepared by the sol-gel technique. These films contain high amounts of hydrophobic methyl groups at the pore surface and do not absorb moisture making possible their use as low-index layers in interferential antireflective devices. Besides, these films also appear as good hosts for photochromic dyes leading to coatings for optical switching devices. Methyl groups and mesoporosity offer optimized environments for photochromic dyes dispersed by multiimpregnation technique.
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Authors: Mario Llusar, Carina Gargori, Sara Cerro, Jose Antonio Badenes, Guillermo Monrós
Abstract: In this communication we provide some examples of hot research topics in the field of ceramic pigments. The more classical approach of finding new host lattices or chromophores is first illustrated with recent examples of new formulations for yellow-orange, reddish-brown and blue ceramic pigments based on pseudobrookites and related titanates. Then we highlight the advantages of using non-conventional preparation routes, which can provide different pigmenting alternatives for the emerging ink-jet printing technology, such as the development of nanoor sub-micron pigments and “ceramic inks”, or the use of appropriate precursors for in situ-generating pigments.
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Authors: Ekaterina Gotovtseva, Alexander A. Biryukov, Valery Svetlichnyi
Abstract: SiO2-Cd2SiO4@CdS multicomponent composite materials were synthesized in several stages. The structure and morphology of powders obtained were studied. According to SEM data the size of individual particles was about 400 nm. Specific surface area for all the samples did not exceed 1 cm2/g. It was found, that in contradistinction to CdS, composites obtained had high photo-corrosion resistance both to visible and UV-light. On the example of photodegradation of the dye Nile blue in water, it was shown that SiO2-Cd2SiO4@CdS composites had high photocatalytic activity in visible range.
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