Effect of synthesis conditions on the microstructure of TEOS derived silica hydrogels synthesized by the alcohol-free sol–gel route

The layered LiNi1/2Mn1/2O2 cathode materials were synthesized by a sol gel method. The effects of calcination temperature and time on the structural and electrochemical properties of the LiNi1/2Mn1/2O2 were investigated. The prepared samples were characterized by X-ray diffraction (XRD) and electrochemical analysis. The results revealed that the layered LiNi1/2Mn1/2O2 material could be optimal synthesized at temperature of 900°C for 10h. The sample prepared under the above conditions has the highest initial discharge capacity of 151 mAh/g and showed no dramatic capacity fading during 20 cycles between 2.5-4.5V at a current rate of 20mA/g.

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Ceramics for the Immobilization of Plutonium and Americium: Current Progress of R&D of the V.G. Khlopin Radium Institute

MRS Proceedings ◽

10.1557/proc-807-207 ◽

2003 ◽

Vol 807 ◽

Cited By ~ 6

Author(s):

Evgeniy B. Anderson ◽

Boris E. Burakov

Keyword(s):

Sol Gel ◽

Tetragonal Zirconia ◽

Ceramic Materials ◽

Khlopin Radium Institute ◽

Radium Institute ◽

Crystalline Materials ◽

Synthesis Conditions ◽

Mixed Oxide Fuel ◽

Air Atmosphere ◽

Environmentally Safe

ABSTRACTSince 1990, the Laboratory of Applied Mineralogy and Radiogeochemistry of the V.G. Khlopin Radium Institute (KRI) has been developing several different types of crystalline host-phases acceptable for the economically feasible and environmentally safe immobilization of actinide wastes. We proposed that ceramics that are based on host phases similar to naturally occurring accessory minerals including zircon, (Zr,Hf,…)SiO4; hafnon, (Hf,Zr,…)SiO4; baddeleyite (monoclinic zirconia), (Zr,Hf,…)O2; tazheranite (cubic zirconia), (Zr,Hf,Ca,Ti,…)O2; garnet, (Ca,Fe,Gd,…)3(Al,Fe,Si,…)5O12; perovskite, (Ca,Gd,…)(Al,Fe,Ti,…)O3, and monazite, (La,Ce,…)PO4, are the most efficient materials for actinide immobilization in deep geological formations. Solid solution of Pu in zirconia, (Zr,Pu)O2, could be used as a ceramic nuclear fuel that is competitive with mixed oxide fuel (MOX). To date, the following crystalline materials doped with 239Pu, 238Pu and 243Am have been successfully synthesized and studied at KRI: zircon; hafnon; cubic and tetragonal zirconia; monazite; aluminate garnet and perovskite. The maximum actinide loading was (in wt.% el.): 239Pu -37; 238Pu-10; 243Am-23. All Pu-Am-doped samples were made in air atmosphere under glove boxes conditions. Polycrystalline (ceramic) materials were made by sintering or melting of sol-gel, co-precipitated hydroxides, oxalates and phosphates or ground oxide precursors; single crystals were grown by a flux method. It was demonstrated that all ceramic samples obtained are characterized by high chemical durability and typical normalized actinide losses in deionized water at 90°C do not exceed 10−2–10−3 g/m2 (without correction for ceramic porosity). However, investigation of long-term behavior of ceramic waste forms requires taking into account the results of accelerated radiation damage study and modeling of ceramic alteration by underground solutions. The principal features of Pu-Am-doped samples obtained so far at KRI and their synthesis conditions are discussed.

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Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

Butlerov Communications ◽

10.37952/roi-jbc-01/20-63-7-126 ◽

2020 ◽

Vol 63 (7) ◽

pp. 126-132

Author(s):

Lyubov V. Furda ◽

◽

Evgenia A. Tarasenko ◽

Sofya N. Dudina ◽

Olga E. Lebedeva ◽

...

Keyword(s):

Surface Area ◽

Sol Gel ◽

Molar Ratio ◽

Active Centers ◽

Indicator Method ◽

Synthesis Conditions ◽

Alkaline Conditions ◽

Acidic Conditions ◽

Amphoteric Properties ◽

Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

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Hybrid Sol-Gel Coatings

Production, Properties, and Applications of High Temperature Coatings - Advances in Chemical and Materials Engineering ◽

10.4018/978-1-5225-4194-3.ch013 ◽

2018 ◽

pp. 334-380 ◽

Cited By ~ 1

Author(s):

Rita Bacelar Figueira

Keyword(s):

Sol Gel ◽

Inorganic Materials ◽

Mechanical And Thermal Properties ◽

Metallic Substrates ◽

Gel Method ◽

Sol Gel Method ◽

Application Range ◽

Synthesis Conditions ◽

Optical And Mechanical Properties ◽

Significant Attention

The properties and wide application range of organic-inorganic hybrid (O-IH) sol-gel materials have attracted significant attention over the past decades. The combination of organic polymers and inorganic materials in a single-phase provides exceptional possibilities to tailor electrical, optical and mechanical properties concerning diverse applications. This unlimited design concept has led to the development of diverse coatings for several applications such as glasses, and metals to mitigate mechanical abrasion, erosion and corrosion. This class of materials could be easily obtained by sol-gel method at mild synthesis conditions. Furthermore, the large variety of available chemical precursors allows producing a diversity of coatings with tuned mechanical and thermal properties. This chapter will introduce the fundamentals of the sol-gel method to produce O-IH protective thin coatings and discuss the methodologies used to apply these materials onto different metallic substrates for erosion and corrosion protection.

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Structural Characterization and CO Oxidation Activity of Nanostructured LaMnO3 Catalysts

Australian Journal of Chemistry ◽

10.1071/ch02081 ◽

2002 ◽

Vol 55 (12) ◽

pp. 757 ◽

Cited By ~ 4

Author(s):

Min Chen ◽

Huai-Qing Huang ◽

Xiao-Ming Zheng ◽

Michael A. Morris

Keyword(s):

Co Oxidation ◽

Sol Gel ◽

X Ray Diffraction ◽

Total Oxidation ◽

Oxidation Activity ◽

Preparation Methods ◽

Synthesis Conditions ◽

Nanostructured Particles ◽

Transmission Electron ◽

Perovskite Type

Perovskite-type LaMnO3 catalysts were prepared by three different methods and tested for CO oxidation. The structural character of the catalysts was investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). All three different preparation methods resulted in nanostructured particles forming in the LaMnO3 catalysts. The crystallite size was in the range of 20 to 80 nm depending on the synthesis conditions. It was possible to synthesize the smallest particle size and a pure phase of perovskite-type LaMnO3 oxide by using a sol–gel method. The results also indicated that the CO total oxidation activity was related to the size of LaMnO3 particle and the structure formed.

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A comparative study of the pressureless sinterability of 3 mol% Y 2 O 3 -stabilized ZrO 2 powders prepared by the sol–gel method under different synthesis conditions without modifiers

Ceramics International ◽

10.1016/j.ceramint.2014.08.015 ◽

2014 ◽

Vol 40 (10) ◽

pp. 16829-16834 ◽

Cited By ~ 2

Author(s):

Nadia Mamana ◽

Angel L. Ortiz ◽

Florentino Sánchez-Bajo ◽

Ricardo Caruso

Keyword(s):

Comparative Study ◽

Sol Gel ◽

Gel Method ◽

Sol Gel Method ◽

Synthesis Conditions

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Organic Hydrogel Templates for Tunable Mesoporous Silica Hybrid Materials

MRS Proceedings ◽

10.1557/opl.2015.38 ◽

2015 ◽

Vol 1721 ◽

Cited By ~ 1

Author(s):

Jennifer L. Kahn ◽

Necla Mine Eren ◽

Osvaldo Campanella ◽

Sherry L. Voytik-Harbin ◽

Jenna L. Rickus

Keyword(s):

Mesoporous Silica ◽

Hybrid Materials ◽

Collagen Fibril ◽

Film Formation ◽

Sol Gel ◽

Collagen Matrix ◽

Silica Coating ◽

Absolute Amount ◽

Microstructural Properties ◽

Synthesis Conditions

ABSTRACTPorous coatings at the surface of living cells have application in human cell transplantation by controlling the transport of biomolecules to and from the cells. Sol-gel-derived mesoporous silica materials are good candidates for such coatings, owing to their biocompatibility, facile solution-based synthesis conditions, and thin film formation. Diffusion and transport across the coating correlates to long-range microstructural properties, including pore size distribution, porosity, and pore morphology. Here, we investigated collagen-fibril matrices with known biocompatibility to serve as templating systems for directed silica deposition. Type 1 collagen oligomers derived from porcine skin are extensively characterized such that we can predict and customize the final collagen-fibril matrix with respect to fibril density, interfibril branching and viscoelasticity. We show that these matrices template and direct the deposition of mesoporous silica at the level of individual collagen fibrils. We varied the fibril density, silicic acid concentration, and time of exposure to silicifying solution and characterized the resulting hybrid materials by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and rheology. Microstructural properties of the collagen-fibril template are preserved in the silica surface of hybrid materials. Results for three different collagen fibril densities, corresponding to shear storage moduli of 200 Pa, 1000 Pa, and 1600 Pa, indicate that increased fibril density increases the absolute amount of templated silica when all other silica synthesis conditions are kept constant. Additionally, mechanical properties of the hybrid material are dominated by the presence of the silica coating rather than the starting collagen matrix stiffness.

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RAMAN STUDY OF VANADIUM-DOPED TITANIA NANOPOWDERS SYNTHESIZED BY SOL-GEL METHOD

International Journal of Modern Physics B ◽

10.1142/s0217979210064289 ◽

2010 ◽

Vol 24 (06n07) ◽

pp. 667-675 ◽

Cited By ~ 1

Author(s):

M. ŠĆEPANOVIĆ ◽

S. AŠKRABIĆ ◽

M. GRUJIĆ-BROJČIN ◽

A. GOLUBOVIĆ ◽

Z. DOHČEVIĆ-MITROVIĆ ◽

...

Keyword(s):

Raman Spectra ◽

Structural Characteristics ◽

Anatase Phase ◽

Sol Gel ◽

X Ray Diffraction ◽

Gel Method ◽

Sol Gel Method ◽

Synthesis Conditions ◽

Raman Modes ◽

Doped Titania

Pure titania ( TiO 2) nanopowders and TiO 2 doped with 10 mol % of vanadium ions ( V 3+) are synthesized by sol-gel method. The dependence of structural characteristics of nanopowders on synthesis conditions is investigated by X-ray diffraction and Raman spectroscopy. Very intensive modes observed in Raman spectra of all nanopowders are assigned to anatase phase of TiO 2. Additional Raman modes of extremely low intensity which can be related to the presence of small amount of brookite amorphous phase are observed in pure TiO 2 nanopowders. In V -doped nanopowders anatase was the only TiO 2 phase detected. The variations in duration and heating rate of calcination influence slightly the Raman spectra of pure TiO 2, but have a great impact on Raman modes of anatase, as well as the additional Raman modes related to the presence of vanadium oxides in V -doped samples.

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