Sample records for non-aqueous sol-gel route

  1. Characterization of TiO 2 powders and thin films prepared by non-aqueous sol–gel techniques

    Microsoft Academic Search

    Nursen Avci; Philippe F. Smet; Hilde Poelman; Nigel Van de Velde; Klaartje De Buysser; Isabel Van Driessche; Dirk Poelman

    2009-01-01

    Stable TiO2 sols were prepared using two non-aqueous sol–gel processes with titanium n-butoxide and titanium isopropoxide, respectively. Crystallization and phase transitions of powders and thin films were studied\\u000a by ex situ and in situ X-ray diffraction. For both methods, TiO2 began to crystallize around 320 °C in air. Using helium instead of air during heat treatment slowed down the crystallization\\u000a and

  2. Optical and structural properties of aluminium oxide thin films prepared by a non-aqueous sol–gel technique

    Microsoft Academic Search

    Nursen Avci; Philippe F. Smet; Johan Lauwaert; Henk Vrielinck; Dirk Poelman

    Clear aluminium oxide sols without precipitation were synthesized via a non-aqueous sol–gel technique using three different\\u000a alcohols (ethanol, isopropanol and n-butyl alcohol) as solvent, aluminium sec-butoxide as a precursor and acetyl acetone as\\u000a a chelating agent. Although all sols could be successfully used to prepare thin films, the most stable one was prepared with\\u000a n-butyl alcohol. Highly transparent, homogenous and

  3. Nano Imprint Lithography on Silica Sol-gels: a simple route to sequential patterning**

    E-print Network

    Paris-Sud XI, Université de

    and glass substrates, would be a low pressure patterning technique on a directly functional thin film1 Nano Imprint Lithography on Silica Sol-gels: a simple route to sequential patterning or resist omitting the final pattern transfer step. In that respect, inorganically cross-linked sol-gel

  4. Preparation of nanocrystalline CuAlO 2 through sol–gel route

    Microsoft Academic Search

    C. K. Ghosh; S. R. Popuri; T. U. Mahesh; K. K. Chattopadhyay

    2009-01-01

    Nanocrystalline powders of CuAlO2 were synthesized through sol–gel method using nitrate-citrate route and also through solid state reaction method. We used\\u000a a new set of precursor materials for the synthesis of CuAlO2 through sol–gel route which were not reported in the past. A little lowering of the synthesis temperature (1,000 °C) was\\u000a observed in case of sol–gel process compared to the

  5. Sol-gel route to the tunneled manganese oxide cryptomelane

    SciTech Connect

    Ching, S.; Roark, J.L. [Connecticut College, New London, CT (United States)] [Connecticut College, New London, CT (United States); Duan, N.; Suib, S.L. [Univ. of Connecticut, Storr, CT (United States)] [Univ. of Connecticut, Storr, CT (United States)

    1997-03-01

    The sol-gel reaction between KMnO{sub 4} and fumaric acid in a 3:1 mole ratio generates a flocculant gel that serves as a precursor to the tunneled manganese oxide, cryptomelane. The elemental composition of sol-gel cryptomelane has been determined to be K{sub 0.12}MnO{sub 2.0-} (H{sub 2}O){sub 0.09}. Further characterization has been performed using powder X-ray diffraction, scanning electron microscopy, and Auger electron spectroscopy. The sol-gel process is heavily dependent on reactant concentration. Solutions that are too concentrated produce the layered manganese oxide birnessite, whereas overly dilute reactions yield mixtures of cryptomelane and Mn{sub 2}O{sub 3}. The preference for cryptomelane over birnessite correlates with low potassium content in the gel. The sol-gel procedure for synthesizing cryptomelane is not easily transferred to the preparation of analogous manganese oxides with different tunnel cations. Reactions that employ permanganates other than KMnO{sub 4} generally yield Mn{sub 2}O{sub 3}, with cryptomelane being a minor product at best. Thermal analyses of cryptomelane gels indicate that calcination proceeds through a series of stages that involve loss of water, loss of residual organics, conversion to cryptomelane, and finally degradation to Mn{sub 3}O{sub 4}. The extraction of potassium ions from sol-gel cryptomelane by various foreign cations is minimal, with the loss of K{sup +} being on the order of 10%. 49 refs., 7 figs., 3 tabs.

  6. Structural, magnetic and electrical properties of cobalt ferrites prepared by the sol–gel route

    Microsoft Academic Search

    I. H. Gul; A. Maqsood

    2008-01-01

    Nanosized cobalt ferrites having the general formula CoFe2?xAlxO4 (for x=0.00, 0.25, 0.50) have been synthesized by the sol–gel route. The effect of Al3+ ions on structural, Curie temperature, DC electrical resistivity and dielecltric properties are presented in this paper. From the analysis of powder X-ray diffraction patterns, the nanocrystallite size was calculated by the most intense peak (311) using Scherrer

  7. EXAFS study of ceria–lanthana-based TWC promoters prepared by sol–gel routes

    Microsoft Academic Search

    Francesca Deganello; Alessandro Longo; Antonino Martorana

    2003-01-01

    Extended X-ray absorption fine structure (EXAFS) experiments at the Ce K- and La K-edges were performed on ceria–lanthana–alumina three-way catalysts promoters prepared by sol–gel routes, in order to investigate the effect of lanthanum doping on the ceria structure. The formation of Ce1?xLaxO2?x\\/2 solid solution, already observed by X-ray diffraction, was confirmed by EXAFS analysis, while no experimental evidence of a

  8. Photoluminescence properties of sesquioxide doped ceria synthesized by modified sol–gel route

    Microsoft Academic Search

    Manas Kumar Rath; Susant Kumar Acharya; Bok-Hee Kim; Ki Tae Lee; Byung Guk Ahn

    2011-01-01

    Highly crystalline and porous sesquioxide (Sm2O3, La2O3) doped ceria with different molar ratio is successfully synthesized by a simple modified sol–gel route. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) are used to investigate their phase, microstructure and composition. XRD analysis confirmed the formation of highly crystalline cubic fluorite phase in all samples. The Raman

  9. Preparation of LiTaO 3 nanoparticles by a sol–gel route

    Microsoft Academic Search

    Y. G. Liu; J. H. Hu; Z. H. Huang; M. H. Fang

    2011-01-01

    A sol–gel route was developed to prepare pure ultrafine LiTaO3 powders using Ta2O5, Li2CO3, citric acid (CA) as chelating agent, ethylene glycol (EG) as esterification agent and polyethylene glycol (PEG) as dispersant.\\u000a The effects of pH value and heat treatment temperature of powder precursor on the synthesis of LiTaO3 powders were investigated. The phase content and morphology of the final

  10. Influence of process parameters on the synthesis of nano-titania by sol–gel route

    Microsoft Academic Search

    Sahil Sahni; S. Bhaskar Reddy; B. S. Murty

    2007-01-01

    Nano-rutile-titania has been synthesized via a sol–gel route using titanium tetra n-butoxide as the precursor and ethyl alcohol as the solvent at a low temperature of 80°C. When synthesized with HCl as the catalyst, the powders crystallized without calcination, while the materials prepared using acetylacetone as the catalyst required heating to ?300°C to initiate the crystallization. The anatase to rutile

  11. Zirconium titanate synthesis by diethanol amine based sol-gel route

    Microsoft Academic Search

    S. Naci Koç

    2006-01-01

    ZrTiO4 powder are synthesized by a modified sol-gel route via bimetallic diethanol amine complex of zirconium and titanium alkoxides.\\u000a Samples are cured at 140C and calcined between 500–800C. Powders are characterized with XRD, TGA, DTA, SEM and TEM methods.\\u000a The ZrTiO4 powders are obtained at 650C from the amorphous form. No identified peaks can be attibuted to other phases, namely,

  12. Sol–gel route to synthesize titania-silica nano precursors for photoactive particulates and coatings

    Microsoft Academic Search

    V. S. Smitha; K. A. Manjumol; K. V. Baiju; Swapankumar Ghosh; P. Perumal; K. G. K. Warrier

    2010-01-01

    Nano titanium dioxide sols containing silica in the range 5–50 mol% have been synthesized using sol–gel route starting from\\u000a titanyl sulphate with a view of developing antisoiling surfaces. The titania sol had an average particle size of ~30 nm while\\u000a the average size of titania-silica sol was 61 nm. The influence of silica addition on the phase transition and grain growth\\u000a of nanocrystalline

  13. Synthesis of Sol-Gel Matrices for Encapsulation of Enzymes Using an Aqueous Route

    SciTech Connect

    Ashley, C.S.; Bhatia, R.B.; Brinker, C.J.; Harris, T.M.

    1998-11-23

    Sol-gel matrices are promising host materials for potential chemical and biosensor applications. Previous studies have focused on modified sol-gel routes using alkoxides for encapsulation of enzymes. However the formation of alcohol as a byproduct during hydrolysis and condensation reactions poses limitations. We report the immobilization of glucose oxidase and peroxidase in silica prepared by an aqueous route which may provide a more favorable environment for the biomolecules. A two step aqueous sol-gel procedure using sodium silicate as the precursor was developed to encapsulate the enzymes and the dye precursor, o-dianisidine. Glucose oxidase catalyzes the oxidation of glucose to give gluconic acid and hydrogen peroxide. Peroxidase then catalyzes the reaction of the dye precursor with hydrogen peroxide to produce a colored product. The kinetics of the coupled enzymatic reactions were monitored by optical spectroscopy and compared to those occurring in tetramethyl orthosilicate (TMOS) derived silica matrices developed by Yamanaka. Enhanced kinetics in the aqueous silicate matrices were related to differences in the host microstructure as elucidated by microstructural comparisons of the corresponding aerogels.

  14. Synthesis and characterization of (Zn, Mn)TiO 3 by modified sol–gel route

    Microsoft Academic Search

    Mingzhen Zheng; Xianran Xing; Jinxia Deng; Lu Li; Jie Zhao; Lijie Qiao; Chunying Fang

    2008-01-01

    Hexagonal ilmenite-type (Zn1?xMnx)TiO3 (0?x?0.9) ceramic powders were synthesized by a sol–gel route including the Pechini process with heat treatments at 600°C for 3h and 800°C for 6h. The thermal stability of ZnTiO3 dielectric ceramics was improved (>1200°C) by doping manganese. The dielectric constant of (Zn1?xMnx)TiO3 ceramic was higher than those of (Zn, M)TiO3 (M=Co, Ni, etc.), increased with the amount

  15. Spectroscopic investigations of nanohydroxyapatite powders synthesized by conventional and ultrasonic coupled sol–gel routes

    Microsoft Academic Search

    D. Gopi; K. M. Govindaraju; Collins Arun Prakash Victor; L. Kavitha; N. Rajendiran

    2008-01-01

    In the present work, the synthesis and characterization of nano-HAP powders by a novel ultrasonic coupled sol–gel synthesis is reported. The obtained powders were sintered by conventional means at different temperatures. In addition to this, HAP powders prepared through the sol–gel method without the aid of the ultrasonic waves is also studied. The obtained nano-HAP powders were characterized by Fourier

  16. Transport properties of V 2O 5\\/polypyrrole nanocomposite prepared by a sol-gel alkoxide route

    Microsoft Academic Search

    Fritz Huguenin; Emerson M Girotto; Roberto M Torresi; Daniel A Buttry

    2002-01-01

    Nanocomposites of V2O5 xerogel and polypyrrole (Ppy) were prepared from a vanadyl tris(isopropoxide) precursor and pyrrole monomer by in situ oxidative polymerization of the pyrrole in the sol stage followed by gelation. Unlike previous sol-gel nanocomposite synthetic routes, the gel forms a stable solution from which thin homogeneous films can be cast. The nanocomposite was characterized by XRD, FTIR and

  17. Phase Analysis and Oxygen Storage Capacity of Ceria-Lanthana-Based TWC Promoters Prepared by Sol–Gel Routes

    Microsoft Academic Search

    Francesca Deganello; Antonino Martorana

    2002-01-01

    Ceria–lanthana-based promoters of three-way catalysts are synthesized by two different sol–gel routes, involving nitrate precursors. The oxygen uptake ability of these compounds is measured by O2 chemisorption. The specific surface area is determined by N2 adsorption (BET). X-ray diffraction data are analyzed by Rietveld refinement, demonstrating that lanthanum forms solid solution with CeO2; its total amount in ceria depends on

  18. Preparation of SDC electrolyte thin films on dense and porous substrates by modified sol–gel route

    Microsoft Academic Search

    Hongfei Lin; Changsheng Ding; Kazuhisa Sato; Yoshifumi Tsutai; Hiromichi Ohtaki; Mabito Iguchi; Chiharu Wada; Toshiyuki Hashida

    2008-01-01

    Nanocrystalline fluorite type samarium doped ceria (SDC) electrolyte thin film for intermediate temperature-solid oxide fuel cells (IT-SOFCs) application were prepared on the dense and porous substrates at low temperatures of 573–1373K using a novel citrate sol–gel route combined with a sol suspension spray coating technique. Thermogravimetric analysis showed that the decomposition of the citrate gel film and the initial crystallization

  19. Fabrication of silica nanocoatings on ZnS-type phosphors via a sol–gel route using cetyltrimethylammonium chloride dispersant

    Microsoft Academic Search

    Jiongliang Yuan; Koji Kajiyoshi; Kazumichi Yanagisawa; Hideki Sasaoka; Kazuhito Nishimura

    2006-01-01

    In order to apply ZnS-type phosphors in field emission displays (FEDs), their poor ageing performance, resulting from their surface oxidation at high current densities, should be improved. In this study, the green emitting ZnS:Ag,Cl phosphors are covered with uniform and continuous SiO2 coatings via a sol–gel route, which is expected to inhibit their surface oxidation. During the gelation process, cetyltrimethylammonium

  20. EXAFS study of ceria-lanthana-based TWC promoters prepared by sol-gel routes

    NASA Astrophysics Data System (ADS)

    Deganello, Francesca; Longo, Alessandro; Martorana, Antonino

    2003-11-01

    Extended X-ray absorption fine structure (EXAFS) experiments at the Ce K- and La K-edges were performed on ceria-lanthana-alumina three-way catalysts promoters prepared by sol-gel routes, in order to investigate the effect of lanthanum doping on the ceria structure. The formation of Ce 1- xLa xO 2- x/2 solid solution, already observed by X-ray diffraction, was confirmed by EXAFS analysis, while no experimental evidence of a Ce-Al interaction was found. In presence of cerium and aluminum, lanthanum is involved in the formation of solid solution with CeO 2 and of La-Al compounds. When the La:Al molar ratio is sufficiently high, the growth of a tridimensionally ordered LaAlO 3 perovskite compound is observed. For increasing values of x/1- x in the solid solution Ce 1- xLa xO 2- x/2 , the Ce-O distance decreases, while La-O distance remains nearly constant.

  1. A new synthesis route to high surface area sol gel bioactive glass through alcohol washing

    PubMed Central

    M. Mukundan, Lakshmi; Nirmal, Remya; Vaikkath, Dhanesh; Nair, Prabha D.

    2013-01-01

    Bioactive glass is one of the widely used bone repair material due to its unique properties like osteoconductivity, osteoinductivity and biodegradability. In this study bioactive glass is prepared by the sol gel process and stabilized by a novel method that involves a solvent instead of the conventional calcinations process. This study represents the first attempt to use this method for the stabilization of bioactive glass. The bioactive glass stabilized by this ethanol washing process was characterized for its physicochemical and biomimetic property in comparison with similar composition of calcined bioactive glass. The compositional similarity of the two stabilized glass powders was confirmed by spectroscopic and thermogravimetric analysis. Other physicochemical characterizations together with the cell culture studies with L929 fibroblast cells and bone marrow mesenchymal stem cells proved that the stabilization was achieved with the retention of its inherent bioactive potential. However an increase in the surface area of the glass powder was obtained as a result of this ethanol washing process and this add up to the success of the study. Hence the present study exhibits a promising route for high surface area bioactive glass for increasing biomimicity. PMID:23512012

  2. An alternative sol–gel route for the preparation of thin films in CeO 2–TiO 2 binary system

    Microsoft Academic Search

    Tongjit Kidchob; Luca Malfatti; Daniela Marongiu; Stefano Enzo; Plinio Innocenzi

    2010-01-01

    Thin films of titania–ceria have been prepared via sol–gel processing by employing titanium and cerium chloride compounds in highly acidic conditions for the precursor sol. This sol–gel route allows obtaining titania–ceria and cerium titanate films, CeTi2O6, after thermal treatment in air. The films exhibit a high optical transparency which is modulated by controlling the composition and the thermal treatment. The

  3. Preparation of NiFe2O4 thin films by a new route sol-gel

    Microsoft Academic Search

    J. V. A. Santos; J. G. S. Duque; J. M. Sasaki; E. A. S. Junior; M. A. Macedo

    2002-01-01

    Summary form only given. We describe a new route of preparation of NiFe2O4 thin films, utilizing a sol-gel process which uses coconut water as the solvent for metal salts. This new route has obtained good results in the preparation of CoFe2O4 thin films by Duque et al. (2000; 2001). Stoichiometric quantities of Fe(NO3)3.9H2O and Ni(NO3)2.6H2O were dissolved in filtered coconut

  4. Synthesis of mesoporous chromium phosphate through an unconventional sol–gel route

    Microsoft Academic Search

    A. Tarafdar; Susanta Biswas; N. K. Pramanik; P. Pramanik

    2006-01-01

    Mesoporous chromium (III) phosphate has been synthesized first time using an unconventional sol–gel technique using inexpensive chromium source ammonium dichromate. In situ synthesized chromium (III), prepared through reduction of ammonium dichromate using ethanol and nitric acid, forms gel in presence of ammonium dihydrogen phosphate and urea at elevated temperature where tetradecyltrimethylammonium bromide (TTBr) is used as structure directing agent. High

  5. Inorganic environment derived f rom the sol-gel route does not improve the thermal

    E-print Network

    Prentiss, Mara

    and on SiC (Do, degradation of organic moleculesincluded in sol gel matrices,then a coating of SiO2 should retard degradation.We hypothesizedthat the placement of a barrier to oxygen diffusion the coating of dense and of porous* SiO2 (Figures 1

  6. Effect of Niobium Modifications to PZT (53\\/47) Thin Films Made by a Sol-Gel Route

    Microsoft Academic Search

    Rajnish Kurchania; Steven J. Milne

    2003-01-01

    Niobium-modified lead zirconate titanate thin films (PNZT) with nominal compositions, Pb(1-0.5x) (Zr0.53 Ti0.47)1-x NbxO3:x = 0.02–0.07, have been prepared using a diol based sol-gel route. Single-layer (0.5 µm) films were fabricated on platinised silicon substrates by spin-coating. The effect of niobium additions with regard to phase development, microstructure, and ferroelectric and dielectric properties were investigated for different annealing temperatures. For

  7. Catalytic coatings on stainless steel prepared by sol–gel route

    Microsoft Academic Search

    Dimitri Truyen; Matthieu Courty; Pierre Alphonse; Florence Ansart

    2006-01-01

    Stainless steel (flat and microstructured) substrates have been coated with sol–gel catalysts made up of metal nanoparticles (Rh, Ni, Pt) dispersed on alumina and alumina–ceria supports. The aluminum monohydroxyde (boehmite) sols were synthesized by hot hydrolysis\\/peptization of an aluminum alkoxide (Yoldas method). It is shown that the rheological properties of the sol, especially the thixotropy, play a key role on

  8. Production and characterization of spodumene dosimetric pellets prepared by a sol-gel route

    NASA Astrophysics Data System (ADS)

    Lima, H. R. B. R.; Nascimento, D. S.; Bispo, G. F. C.; Teixeira, V. C.; Valério, M. E. G.; Souza, S. O.

    2014-11-01

    Spodumene is an aluminosilicate that has shown good results for high-dose TL dosimetry for beta or gamma rays. Due to its chemical composition (LiAlSi2O6) it has potential to be used as a neutron dosimeter. The synthetic spodumene is usually produced by solid state reaction and conventional sol-gel, whose shortcomings arise from the need to employ high temperatures and high cost reagents, respectively. Proteic sol-gel method is promising, because it can reduce production costs and the possibility of environmental contamination. This work reports the production of the spodumene by the proteic sol-gel method using edible unflavored gelatin as a precursor. The product is characterized physically and morphologically, and investigated its applicability as a TL dosimeter. Two sets of samples were prepared using different sources of silicon, one with TEOS (Si(OC3H5)4) and one with SILICA (SiO2). The materials produced were characterized by X-ray diffraction, differential thermal analysis and thermogravimetry in order to evaluate the structural properties, as well as possible changes in physical or chemical properties depending on the temperature. The production of spodumene was successful, with generation of the crystals in the ?-phase with tetragonal structure. Sintered pellets produced from these crystals were irradiated with a 90Sr-90Y source and their TL glow curves were evaluated. Although the samples prepared by the proteic sol-gel method with TEOS presented a lower forming temperature, the samples produced with SILICA showed higher sensitivity to radiation.

  9. Preparation and nonlinear optical properties of indium nanocrystals in sodium borosilicate glass by the sol–gel route

    SciTech Connect

    Zhong, Jiasong [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)] [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China) [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhao, Haijun; Chen, Zhaoping [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)] [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Liang, Xiaojuan [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)] [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhao, Wenguang; Chen, Guoxin [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)] [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2012-11-15

    Graphical abstract: The sodium borosilicate glass doped with indium nanocrystals have been successfully prepared by sol–gel methods. And the indium nanocrystals in tetragonal crystal system have formed uniformly in the glass, and the average diameter of indium nanocrystals is about 30 nm. The third-order optical nonlinear refractive index ?, absorption coefficient ?, and susceptibility ?{sup (3)} of the glass are determined to be ?4.77 × 10{sup ?16} m{sup 2}/W, 2.67 × 10{sup ?9} m/W, and 2.81 × 10{sup ?10} esu, respectively. Highlights: ? Indium nanocrystals embedded in glass matrix have been prepared by sol–gel route. ? The crystal structure and composition are investigated by XRD and XPS. ? Size and distribution of indium nanocrystals is determined by TEM. ? The third-order optical nonlinearity is investigated by using Z-scan technique. -- Abstract: The sodium borosilicate glass doped with indium nanocrystals have been successfully prepared by sol–gel route. The thermal stability behavior of the stiff gel is investigated by thermogravimetric (TG) and differential thermal (DTA) analysis. The crystal structure of the glass is characterized by X-ray powder diffraction (XRD). Particle composition is determined by X-ray photoelectron spectroscopy (XPS). Size and distribution of the nanocrystals are characterized by transmission electron microscopy (TEM) as well as high-resolution transmission electron microscopy (HRTEM). Results show that the indium nanocrystals in tetragonal crystal structure have formed in glass, and the average diameter is about 30 nm. Further, the glass is measured by Z-scan technique to investigate the nonlinear optical (NLO) properties. The third-order NLO coefficient ?{sup (3)} of the glass is determined to be 2.81 × 10{sup ?10} esu. The glass with large third-order NLO coefficient is promising materials for applications in optical devices.

  10. New Sol-Gel Route for Processing of PMN Thin Films

    Microsoft Academic Search

    Stephane Parola; Roland Khem; David Cornu; Zian Kighelman; Dragan Damjanovic; Nava Setter

    2003-01-01

    Pyrochlore free Pb(Mg1\\/3Nb2\\/3)O3 (PMN) thin films were prepared from mixed-metal precursors solutions using the sol-gel process. Lead acetate [Pb(CH3COO)2], magnesium acetate [Mg(CH3COO)2] and niobium ethoxide [Nb(C2H5O)5] were used as starting materials, while 2-isopropoxy-ethanol was chosen as solvent. The reactivity of the precursors was investigated in order to understand and control the process and thus to prevent the contamination of the

  11. DC electrical conductivity of nanocrystalline Mn3O4 synthesized through a novel sol-gel route

    NASA Astrophysics Data System (ADS)

    Bose, Vipin C.; Maniammal, K.; Madhu, G.; Veenas, C. L.; Aiswarya Raj, A. S.; Biju, V.

    2015-02-01

    Manganese oxides have generated considerable interest in recent years due to their electronic and magnetic properties with potential industrial applications. Among manganese oxides, Mn3O4 is one of the stable oxides with normal spinel structure and it has variety of important applications. In the present work nanocrystalline Hausmannite, Mn3O4 with phase purity and average crystallite size of 8 nm was synthesized through a novel sol-gel route at a temperature of 0-5°C. The samples were annealed at different temperatures to understand the thermal stability and the structural characterization was done using techniques such as X-ray powder diffraction (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR). The UV visible absorption spectra of the samples show that there are two types of transitions corresponding to Mn2+ ions and Mn3+ ions. The dc electrical conductivity of the samples increases in comparison with that of bulk.

  12. Influence of transition metals on the surface acidic properties of titania prepared by sol-gel route

    SciTech Connect

    Shali, N.B. [Department of Applied Chemistry, Cochin University of Science and Technology, Cochin-22, Kerala (India); Sugunan, S. [Department of Applied Chemistry, Cochin University of Science and Technology, Cochin-22, Kerala (India)]. E-mail: ssg@cusat.ac.in

    2007-09-04

    A series of titania catalysts containing chromium, molybdenum as well as tungsten has been prepared by colloidal sol-gel route using metatitanic acid as the precursor. Structural characterization of the prepared catalysts was done with Energy dispersive X-ray analysis, X-ray diffraction, BET surface area and pore volume measurements. The influence of different transition metals like chromium, molybdenum and tungsten on the surface acidic properties of titania is investigated in detail. Two independent methods have been used to study the surface acidity of these catalyst systems: temperature programmed desorption of ammonia which is a measure of total acidity and thermodesorption studies using 2,6-dimethyl pyridine which is a measure of Bronsted acidity. Cumene cracking reaction is carried out over the prepared systems for further characterizing the acidity of the prepared catalysts. Remarkable enhancement in the surface acidity is observed after transition metal incorporation. The catalytic activity of the prepared catalysts was tested towards the dehydrogenation of cyclohexane.

  13. Synthesis of Yttria-Stabilized Zirconia Aerogels by a Non-Alkoxide Sol-Gel Route

    SciTech Connect

    Chervin, C N; Clapsaddle, B J; Chiu, H W; Gash, A E; Satcher, Jr., J H; Kauzlarich, S M

    2005-02-11

    Homogeneous, nanocrystalline powders of yttria-stabilized zirconia were prepared using a nonalkoxide sol-gel method. Monolithic gels, free of precipitation, were prepared by addition of propylene oxide to aqueous solutions of Zr{sup 4+} and Y{sup 3+} chlorides at room temperature. The gels were dried with supercritical CO{sub 2}(l), resulting in amorphous aerogels that crystallized into cubic stabilized ZrO{sub 2} following calcination at 500 C. The aerogels and resulting crystalline products were characterized using in-situ temperature profile X-ray diffraction, thermal analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. TEM and N{sub 2} adsorption/desorption analysis of an aerogel indicated a porous network structure with a high surface area (409 m{sup 2}/g). The crystallized yttria-stabilized zirconia maintained high surface area (159 m{sup 2}/g) upon formation of homogeneous, nanoparticles ({approx}10 nm). Ionic conductivity at 1000 C of sintered YSZ (1500 C, 3 hours) prepared by this method, was 0.13 {+-} 0.02 {Omega}{sup -1} cm{sup -1}. Activation energies for the conduction processes from 1000-550 C and 550-400 C, were 0.95 {+-} 0.09 and 1.12 {+-} 0.05 eV, respectively. This is the first reported synthesis and characterization of yttria-stabilized zirconia via an aerogel precursor.

  14. EXAFS study of nanocrystalline CeO 2 samples prepared by sol–gel and ball-milling routes

    Microsoft Academic Search

    Alan V. Chadwick; Shelley L. P. Savin

    2009-01-01

    This paper reports a study of nanocrystalline ceria prepared by both sol–gel and ball-milling methods. EXAFS measurements show that the ball-milled samples contain a considerable fraction of amorphous material, whereas there is a high degree of order in the sol–gel samples of similar grain size. In addition, a study has been made of the effect of silica and alumina as

  15. SrAl2O4: Eu2+, Dy3+ phosphors derived from a new sol-gel route

    Microsoft Academic Search

    Yiqing Lu; Yongxiang Li; Yuhong Xiong; Dong Wang; Qingrui Yin

    2004-01-01

    The SrAl2O4: Eu2+, Dy3+ phosphor powders were prepared by a new sol–gel method using aluminum isopropoxide and strontium acetate as precursors. The sol–gel process and the structure of the phosphor powders were investigated by means of DSC-TG and XRD. It was found that the single-phase SrAl2O4 was formed at 900 °C, which is 300 °C lower than that required for

  16. Luminescent properties and the morphology of SrMoO4:Eu3+ powders synthesized via combining sol-gel and solid-state route

    NASA Astrophysics Data System (ADS)

    Wei, Qiong; Chen, Donghua

    2010-10-01

    SrMoO4:Eu3+ red phosphors were prepared by combining sol-gel and solid-state route. Citric acid and ethylenediaminetetraacetic acid (EDTA), employed as the chelating agents, were added to the aqueous solutions of metal nitrates. X-ray diffraction (XRD) and photoluminescent spectra techniques (PL) were used to characterize the resultant powders. The results indicated the obtained SrMoO4:Eu3+ phosphors were fine powders with a particle size of 50 nm. The effects of synthesizing conditions were also investigated and optimized, which included the synthesis temperature and the activator concentration on the luminescent intensity. Compared with SrMoO4:Eu3+ phosphors prepared by Solid-state reaction SrMoO4:Eu3+ phosphors prepared by combining sol-gel and solid-state route showed appropriate particle size and a higher emission intensity.

  17. Low temperature nanostructured zinc titanate by an aqueous particulate sol–gel route: Optimisation of heat treatment condition based on Zn:Ti molar ratio

    Microsoft Academic Search

    M. R. Mohammadi; D. J. Fray

    2010-01-01

    Nanocrystalline zinc titanate (ZnTiO3) thin films and powders with purity of 94% were produced at the low sintering temperature of 500°C and the short sintering time of 1h by a straightforward aqueous particulate sol–gel route. The effect of Zn:Ti molar ratio was studied on the crystallisation behaviour of zinc titanates. The prepared sols showed a narrow particle size distribution in

  18. A promising sol–gel route based on citric acid to synthesize Li 3V 2(PO 4) 3\\/carbon composite material for lithium ion batteries

    Microsoft Academic Search

    Yuzhan Li; Zhen Zhou; Xueping Gao; Jie Yan

    2007-01-01

    Li3V2(PO4)3\\/carbon composite material was synthesized by a promising sol–gel route based on citric acid using V2O5 powder as a vanadium source. Citric acid acts not only as a chelating reagent but also as a carbon source, which enhance the conductivity of the composite material and hinder the growth of Li3V2(PO4)3 particles. The structure and morphology of the sample were characterized

  19. Fabrication and characterisation of (Ba,Sr)TiO 3 thin films by sol–gel technique through organic precursor route

    Microsoft Academic Search

    N. V Giridharan; R Varatharajan; R Jayavel; P Ramasamy

    2000-01-01

    Ferroelectric thin films of barium strontium titanate (BST) have been deposited on silicon and quartz substrates by sol–gel technique through organic precursor route. Crystalline films were obtained by post deposition annealing at a temperature of 700°C. X-ray diffraction (XRD) studies have been carried out to assess the crystallinity and phase formation. The surface features of the films, studied by optical

  20. Phase Analysis and Oxygen Storage Capacity of Ceria-Lanthana-Based TWC Promoters Prepared by Sol-Gel Routes

    NASA Astrophysics Data System (ADS)

    Deganello, Francesca; Martorana, Antonino

    2002-02-01

    Ceria-lanthana-based promoters of three-way catalysts are synthesized by two different sol-gel routes, involving nitrate precursors. The oxygen uptake ability of these compounds is measured by O2 chemisorption. The specific surface area is determined by N2 adsorption (BET). X-ray diffraction data are analyzed by Rietveld refinement, demonstrating that lanthanum forms solid solution with CeO2; its total amount in ceria depends on the competitive formation of La-Al mixed oxides and on the synthetic method. The O2 uptake ability is essentially determined by the La content in the ceria-lanthana solid solution, while it is independent on the surface area and on the CeO2 particle size. The O2 uptake ability increases with the La:Ce relative amount in the ceria-lanthana solid solution, but decreases beyond a La:Ce molar ratio greater than ?0.18. This behavior is ascribed to the stable association of vacancy-vacancy or vacancy dopant cation.

  1. TPR, TPO, and TPD examinations of Cu 0.15Ce 0.85O 2? y mixed oxides prepared by co-precipitation, by the sol–gel peroxide route, and by citric acid-assisted synthesis

    Microsoft Academic Search

    Albin Pintar; Jurka Batista; Stanko Ho?evar

    2005-01-01

    Temperature-programmed reduction (TPR), oxidation (TPO), and desorption (TPD) studies were performed on three copper–ceria mixed oxide samples having the same nominal composition, Cu0.15Ce0.85O2?y, but prepared in three different ways: by co-precipitation, the sol–gel peroxide route, and the sol–gel citric acid route. The obtained results reveal that despite a drastic initial drop in specific surface area after consecutive redox cycles, the

  2. A novel organic-free sol-gel route to ceria-zirconia-alumina thin films and glassy products

    Microsoft Academic Search

    Elena V. Frolova; Mariya I. Ivanovskaya; Yuliya A. Kosareva; Vitalii P. Petranovskii; Sergio I. Fuentes

    2004-01-01

    Successful preparation of the Ce-Zr-Al oxide thin films and glassy products by a newly developed organic-free modification of the sol-gel technique is reported. The structural composition and some properties of the samples obtained were investigated by TEM, XRD, FTIR, ESR, UV-Vis, PL and XPS. The optical investigation of the obtained films together with ESR data indicate the appearance of the

  3. Microwave-assisted fluorolytic sol-gel route to iron fluoride nanoparticles for Li-ion batteries.

    PubMed

    Di Carlo, Lidia; Conte, Donato E; Kemnitz, Erhard; Pinna, Nicola

    2014-01-14

    A simple microwave-assisted fluorolytic sol-gel synthesis of 30 nm sized FeF3 nanocrystals supported on partially reduced graphene oxide is reported. The as-fabricated nanostructures used as positive electrodes in Li-ion batteries show capacity retention as high as 150 mA h g(-1) even after having sustained repeated charge-discharge cycles. PMID:24257142

  4. Diluted magnetic semiconductor properties in Zn 1?x Cu x O nanoparticles synthesized by sol gel route

    Microsoft Academic Search

    R. Elilarassi; P. Sambasiva Rao; G. Chandrasekaran

    2011-01-01

    Nanoparticles of ZnO:Cu Diluted Magnetic Semiconductor (DMS) are prepared using sol gel method. The structural, optical and\\u000a EPR properties of them are investigated. The XRD patterns of them show the formation of polycrystalline and hexagonal wurtzite\\u000a structure without any secondary phase formation. The average size of particles ranges from 14 to 19 nm. In the optical absorption\\u000a study of the samples,

  5. Gravure-Printed Sol-Gels on Flexible Glass: A Scalable Route to Additively Patterned Transparent Conductors.

    PubMed

    Scheideler, William J; Jang, Jaewon; Karim, Muhammed Ahosan Ul; Kitsomboonloha, Rungrot; Zeumault, Andre; Subramanian, Vivek

    2015-06-17

    Gravure printing is an attractive technique for patterning high-resolution features (<5 ?m) at high speeds (>1 m/s), but its electronic applications have largely been limited to depositing nanoparticle inks and polymer solutions on plastic. Here, we extend the scope of gravure to a new class of materials and on to new substrates by developing viscous sol-gel precursors for printing fine lines and films of leading transparent conducting oxides (TCOs) on flexible glass. We explore two strategies for controlling sol-gel rheology: tuning the precursor concentration and tuning the content of viscous stabilizing agents. The sol-gel chemistries studied yield printable inks with viscosities of 20-160 cP. The morphology of printed lines of antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO) is studied as a function of ink formulation for lines as narrow as 35 ?m, showing that concentrated inks form thicker lines with smoother edge morphologies. The electrical and optical properties of printed TCOs are characterized as a function of ink formulation and printed film thickness. XRD studies were also performed to understand the dependence of electrical performance on ink composition. Printed ITO lines and films achieve sheet resistance (Rs) as low as 200 and 100 ?/?, respectively (? ? 2 × 10(-3) ?-cm) for single layers. Similarly, ATO lines and films have Rs as low as 700 and 400 ?/? with ? ? 7 × 10(-3) ?-cm. High visible range transparency is observed for ITO (86-88%) and ATO (86-89%). Finally, the influence of moderate bending stress on ATO films is investigated, showing the potential for this work to scale to roll-to-roll (R2R) systems. PMID:26018206

  6. A novel organic-free sol-gel route to ceria-zirconia-alumina thin films and glassy products

    NASA Astrophysics Data System (ADS)

    Frolova, Elena V.; Ivanovskaya, Mariya I.; Kosareva, Yuliya A.; Petranovskii, Vitalii P.; Fuentes, Sergio I.

    2004-10-01

    Successful preparation of the Ce-Zr-Al oxide thin films and glassy products by a newly developed organic-free modification of the sol-gel technique is reported. The structural composition and some properties of the samples obtained were investigated by TEM, XRD, FTIR, ESR, UV-Vis, PL and XPS. The optical investigation of the obtained films together with ESR data indicate the appearance of the bulk Ce3+-defects (g? = 1.962-1.967, g// = 1.938-1.940, assigned to 4f1 state, with concentration ~2"1018spin/g). The significant PL intensity rising at elevated temperature was related to spontaneous increasing of Ce3+ concentration in sol-gel samples under thermal dehydration. Also, an unexpected formation of intra-band gap states during thermal treatment of xerogels was manifested in UV-Vis spectra. This intra-band-gap states was attributed to the oxygen related defects that contribute to PL signal.

  7. Optical properties of undoped and Mg doped CuCrO2 powders synthesized by sol-gel route

    NASA Astrophysics Data System (ADS)

    Srinivasan, Radhakrishnan; Bolloju, Satish

    2014-01-01

    In this work, CuCrO2 was synthesized by sol-gel method using citric acid as a gelling agent. The different parameters like ratio of citric acid to metal ions, calcination temperature, and duration were studied. A green colored powder with particle size around 300 nm was formed at the calcination temperature of 800 °C for four hours duration. The increase in temperature has a profound impact on crystallite size and in turn effected the optical properties. Band gap of the obtained CuCrO2 has varied from 2.3 to 1.7 eV by increasing the temperature from 800 °C to 900 °C. Doping studies were performed by introducing Mg2+ ion to substitute Cr3+ in CuCrO2. X-ray powder diffraction and SEM studies on 2% Mg doped samples indicated a clear formation of side phases. According to the X-ray powder patterns, the reflections from side phases were increasing with the increase in doping concentrations of Mg from 2 to 5%. The side phases were found to be MgCr2O4 spinel and CuO. The band gap has decreased for doped samples in comparison to undoped one. In this paper, sol-gel synthesis and characterization by Xray powder diffraction, SEM studies and UV-Vis-Diffuse Reflectance spectra are presented.

  8. Silica Sol-Gel Coatings on Metals Produced by EPD

    Microsoft Academic Search

    Y. Castro; B. Ferrari; R. Moreno; A. Durán

    2003-01-01

    The objective of this work has been to combine the sol-gel method and the electrophoretic deposition (EPD) process to prepare thick coatings onto metallic substrates. Two different routes were used for preparing the sol-gel silica suspensions. On one hand, silica particulate sols were obtained by basic catalysis of alkoxides and alkylalkoxides. On the other, silica suspensions were prepared by adding

  9. Optical spectroscopy study of YVO4:Eu3+ nanopowders prepared by the proteic sol-gel route

    NASA Astrophysics Data System (ADS)

    dos Santos, B. F.; Araujo, R. M.; Valerio, M. E. G.; Rezende, M. V. dos S.

    2015-04-01

    In this study, computational and experimental methods are employed to study the optical properties of YVO4 induced by europium dopant. Atomistic modeling is used to predict the symmetry and the detailed geometry of the dopant site. This information is then used to calculate the crystal-field parameters. Eu-doped YVO4 nanopowders are prepared via a sol-gel proteic technique. Thereafter, multiple techniques including X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to examine the structural properties and surface morphology of the YVO4:Eu3+ phosphors. The optical properties are studied using photoluminescence (PL) and radioluminescence (RL) spectroscopy performed at room temperature. The transition energy of the Eu3+-doped material is compared with the theoretical results. The intensity parameters ?2 and ?4 of Eu3+ in the YVO4 matrix are calculated with the Judd-Ofelt approach.

  10. A Sol-Gel Route for the Synthesis of Bi 2Ru 2O 7 Pyrochlore Oxide for Oxygen Reaction in Alkaline Medium

    NASA Astrophysics Data System (ADS)

    Kahoul, A.; Nkeng, P.; Hammouche, A.; Nâamoune, F.; Poillerat, G.

    2001-11-01

    In this investigation, Bi2Ru2O7 pyrochlore-type oxide was prepared using the Pechini process. We employed a sol-gel route, in which a solution of Ru(III) and Bi(III) in a mixture of citric acid and ethylene glycol was heated to form a polymeric precursor, followed by an annealing at higher temperatures during various periods. The oxide obtained was identified by X-ray diffraction analysis. The results revealed that the formation of homogeneous oxide with a single pyrochlore structure phase occured at or above 650°C. Sample powders consisted of fine grains with homogeneous morphology and an average size of about 0.5 ?m. This new preparation procedure yielded an electrode material with improved electrochemical activity compared to those elaborated through conventional methods.

  11. EPR investigation on synthesis of Lithium zinc vanadate using sol-gel-combustion route and its optical properties

    NASA Astrophysics Data System (ADS)

    Pathak, Nimai; Gupta, Santosh K.; Prince, Angelina; Kadam, R. M.; Natarajan, V.

    2014-01-01

    The present work describes the synthesis of Lithium zinc vanadate (LiZnVO4) nanophosphor prepared by sol-gel-combustion method and its optical properties. The prepared sample was characterized by X-ray diffraction, SEM, electron paramagnetic resonance and photoluminescence spectroscopy. X-ray diffraction study showed the formation of pure LiZnVO4 at 600 °C with distorted phenacite structure. SEM investigation revealed that the phosphor powder has spherical morphology with particle size of about 100-200 nm. EPR study showed the change of coordination sphere around vanadium from axially distorted octahedral symmetry to tetrahedral geometry along with the change in oxidation state of vanadium ion from +4 to +5. The emission spectrum showed a broad emission at 543 nm with ?ex = 375 nm. The decay time obtained on mono-exponential fitting was 8.3 ?s. The colour coordinates of the system were evaluated using CIE index diagram to be 0.31 and 0.41, which suggest that the prepared material is a potential green emitting phosphor. A bright green colour emission was also observed directly from this phosphor upon excitation with an UV source.

  12. Low-Temperature Anode-Supported SOFC with Ultra-Thin Ceria-Based Electrolytes Prepared by Modified Sol—Gel Route

    NASA Astrophysics Data System (ADS)

    Lin, Hongfei; Ding, Changsheng; Sato, Kazuhisa; Tsutai, Yoshifumi; Hashida, Toshiyuki

    The utilization of anode-supported electrolytes is a very promising strategy to improve the electrical performance in solid oxide fuel cells (SOFCs) application, because it is possible to decrease considerably the electrolytes thickness. In this paper, ultra-thin ceria-based electrolyte films were successfully prepared on porous NiO/GDC anode support. The electrolyte films with thickness of 0.5-1 µm were deposited by a novel citrate sol-gel route combined with a suspension spray coating technique. The characterization and microstructure of the ultra-thin films were investigated by DTA/TGA, XRD and FE-SEM. The results showed that ceria-based films prepared were pure fluorite type nanocrystalline, homogenous and almost fully dense. Electrochemical performance of single cells based on the ultra-thin electrolyte films was also tested. The single cell with electrolyte thickness of 1 µm provided an OCV of 0.832 V at 500 °C which was close to that of the reported single cell with thicker ceria-based electrolyte film of 10 µm, and maximum power densities of 59.6, 121.9 and 133.8 mW/cm2 at 500, 600, and 700 °C, respectively. These ultra-thin electrolyte films showed good combination with the porous NiO/GDC anode supports, and good insulating ability for inactive electron migration at temperatures less than 600 °C.

  13. Dielectric Relaxation, Electrical Conductivity and Impedance Response of BaNb2O6 Synthesized by Sol-Gel and Solid State Reaction Route: A Comparative Study

    NASA Astrophysics Data System (ADS)

    Singh, K. N.; Chauhan, B. R.; Bajpai, P. K.

    2011-11-01

    BaNb2O6 (BN)—an important precursor material for the synthesis of lead free relaxors, is synthesized in the nano phase using a modified Sol-Gel route in which the gel is formed by an aqueous solution of BaCl2, NbF5 and citric acid. The gel on decomposition at 700 °C yielded the nano phase of BaNb2O6 with particle size 48 nm. This is the lowest temperature for the formation of BaNb2O. Material is also prepared using the conventional solid state method in which the dominant columbite phase forms at 1100 °C after heating (6 h) with comparatively larger particle size of ˜1 ?m. X-ray diffraction analysis confirms that the BaNb2O6 prepared by both the methods stabilize in orthorhombic crystal structure. Dielectric relaxation is observed and the mechanism of relaxation is elucidated. Conducting charges and free charges both contribute to the dielectric relaxation in the materials. Electrical properties of the materials are studied using impedance spectroscopic technique. Detailed analysis of impedance spectrum suggests that the electrical properties are strongly temperature dependent. AC conduction activation energies are estimated from Arrheneus plots and conduction mechanism is discussed.

  14. A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol-gel auto combustion method and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Nassar, Mostafa Y.; Ahmed, Ibrahim S.; Samir, Ihab

    2014-10-01

    In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350 °C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65 nm was obtained at 800 °C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5 h with pseudo first order rate constants of 5.85 × 10-3 and 8.38 × 10-3 min-1, respectively.

  15. Aero-sol-gel Reactor for Nano-powder Synthesis

    Microsoft Academic Search

    G. Beaucage; J. Hyeon-Lee; D. J. Kohls; S. E. Pratsinis

    1999-01-01

    This paper discusses a new approach to the synthesis of nano-structured oxides where sol-gel reactions are carried out in aerosol droplets. This aero-sol-gel (ASG) reactor allows for manipulation of the structure, chemical composition and surface area of silica powders through variation of process parameters. ASG powders differ in nanostructure from other continuous process powders such as pyrolytic and solution-route powders.

  16. Thermal strain measurement in sol-gel lead zirconate titanate thin films T. A. Berfield,1,a

    E-print Network

    Sottos, Nancy R.

    Thermal strain measurement in sol-gel lead zirconate titanate thin films T. A. Berfield,1,a J. F-plane strain development of blanket sol-gel derived lead zirconate titanate thin films deposited on platinized zirconate titanate PZT , the sol-gel deposition route is particularly attractive as it can lower

  17. Determination of the network structure of sensor materials prepared by three different sol-gel routes using Fourier transform infrared spectroscopy (FT-IR).

    PubMed

    Cappeletti, Larissa B; Moncada, Edwin; Poisson, Joel; Butler, Ian S; Dos Santos, João Henrique Z

    2013-04-01

    Solid acid-base sensor materials were prepared by encapsulating three pH indicators (alizarin red, brilliant yellow, and acridine) within a silica matrix using a sol-gel approach through three different routes: (1) non-hydrolytic, (2) acid-catalyzed, and (3) base-catalyzed. Raman and Fourier transform infrared spectroscopies were used to evaluate the silica-indicator interactions. Because vibrational bands assigned to functional groups present in the indicator molecules were not detected, the main silica stretching mode ?Si-O between approximately 1300 and 1000 cm(-1) was used to detect the presence of our indicators within the silica matrix. The large band centered at 1100 cm(-1) was deconvoluted into four components corresponding to the longitudinal optic and transversal optic modes of the silicon monoxide (SiO)4 and (SiO)6 siloxane rings. Using the component area of each mode, it was possible to calculate the percentage of each structure. Such percentages ranged from 49% to 70% (SiO)6 for the analyzed samples, within a confidence level of 95% (p = 0.05). (The confidence limits were 53-62%.) These results could be related to the pH indicator content, indicating that the quantity of the encapsulated molecule affects the (SiO)6 percentage values. In addition, a comparison with the radius of gyration obtained by small angle X-ray scattering was done. These results indicate that the analyte accesses the receptor elements through the passages between the siloxane rings but not through the siloxane rings themselves. PMID:23601544

  18. Magnetic and 57Fe Mössbauer study of magneto-electric GaFeO3 prepared by the sol-gel route.

    PubMed

    Sharma, Kavita; Raghavendra Reddy, V; Gupta, Ajay; Banerjee, A; Awasthi, A M

    2013-02-20

    This work reports the preparation of magneto-electric GaFeO(3) by the sol-gel route and its characterization by x-ray diffraction, dc-magnetization, ac-susceptibility, low temperature and high field (57)Fe Mössbauer spectroscopy and dielectric constant measurements. The prepared samples are found to be single phase from x-ray diffraction studies. The crystallite sizes are found to be in the nano-regime for the samples sintered at low temperatures. From the temperature dependent dc-magnetization (M-T) measurements, bifurcation of the zero-field cooled (ZFC)-field cooled data and a cusp in the ZFC data are observed. With the help of low-field ac-susceptibility, (57)Fe Mössbauer and detailed dc-magnetic measurements these features are explained in terms of the magnetic anisotropy of the sample ruling out phenomena like spin-glass and super-paramagnetism as quoted in the literature for this compound. Apart from this, very interesting and different M-H behavior mimicking composite two-phase magnets is observed for the samples sintered at different temperatures. A symmetric M-H loop is observed for samples sintered at low temperatures and a pinched M-H loop is observed for samples sintered at high temperatures. The observed magnetic properties are explained by estimating the Fe cation distribution using high field (57)Fe Mössbauer spectroscopy measurements. An anomaly in the dielectric constant data at the Curie temperature indicates the ME coupling of the samples. PMID:23327995

  19. Ternary transition-metal fluoride precursors for the fluorolytic sol-gel route: new insights into speciation and decomposition.

    PubMed

    Kohl, J; Wiedemann, D; Troyanov, S I; Palamidis, E; Lerch, M

    2015-07-14

    The nanoscaled ternary transition-metal fluorides Li3MF6 (M = V, Fe, Mn) and Li2NiF4 are promising candidates for cathode materials in high-voltage lithium-ion batteries. The fluorolytic route to these compounds relies on thermal decomposition of a hitherto uncharacterised precursor mixture produced from acetylacetonates and hydrofluoric acid. By addition of pyridine, different cationic, electroneutral and anionic complexes containing the motifs [MFn]((3-n)+) (n = 0-4) have been trapped and characterised by single-crystal X-ray diffraction and IR spectroscopy. Based on the results, a model of successive and incomplete fluorination is proposed for the speciation and formation of the precursor. The decomposition of the latter has been monitored via thermogravimetry (TG) and differential scanning calorimetry (DSC). PMID:26126969

  20. Structural and optical properties of ZnO: K synthesized by sol-gel auto-combustion route

    NASA Astrophysics Data System (ADS)

    Krithiga, R.; Sankar, S.; Subhashree, G.; Bharathi, R. Niruban

    2015-06-01

    The structural and optical behavior of ZnO and ZnO doped with K synthesized by solution combustion route is reported in this article. The XRD patterns confirm the substitution of K atoms into ZnO lattice. There are no secondary peaks observed in the XRD patterns. The band gap of the K doped samples show a red shift on comparison with the bandgap of ZnO. The photoluminescence spectral study discloses the quenching behavior of UV emission and the aggrandizing blue emission when K content increases. The rich presence of defects is confirmed from the optical analysis and a practical mechanism, involving Zni for the origin of the blue emission in ZnO is discussed here.

  1. Bioactive nanocrystalline sol-gel hydroxyapatite coatings.

    PubMed

    Chai, C S; Ben-Nissan, B

    1999-08-01

    Sol-gel technology offers an alternative technique for producing bioactive surfaces for improved bone attachment. Previous work indicated that monophasic hydroxyapatite coatings were difficult to produce. In the present work hydroxyapatite was synthesized using the sol-gel technique with alkoxide precursors and the solution was allowed to age up to seven days prior to coating. It was found that, similar to the wet-chemical method of hydroxyapatite powder synthesis, an aging time is required to produce a pure hydroxyapatite phase. A methodology that has been successfully used to produce nanocrystalline hydroxyapatite thin film coatings via the sol-gel route on various substrates including alumina, Vycor glass, partially stabilized zirconia, Ti-6Al-4V alloy and single crystal MgO is described. Coatings produced on MgO substrates were characterized by X-ray diffraction and atomic force microscopy, while the analogous gels were examined with thermogravimetric and differential thermal analyses. The coatings were crack free and the surface was covered with small grains, of approximately 200 nm in size for samples fired to 1000 degrees C. Coating thickness varied between 70 and 1000 nm depending on the number of applied layers. PMID:15348113

  2. Comparative study of the synthesis of CoFe 2 O 4 and NiFe 2 O 4 in silica through the polymerized complex route of the sol–gel method

    Microsoft Academic Search

    Sagrario M. Montemayor; L. A. García-Cerda; J. R. Torres-Lubián; O. S. Rodríguez-Fernández

    2007-01-01

    In this work the synthesis of CoFe2O4-SiO2 and NiFe2O4-SiO2 nanocomposites was studied via the sol–gel method, using the polymerized complex route. The polymerized precursors obtained\\u000a by the reaction of citric acid, ethylene glycol, tetraethylorthosilicate, ferric nitrate, and cobalt nitrate or nickel chloride\\u000a were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. NMR and IR spectra of the precursors,

  3. Sol-gel derived sorbents

    DOEpatents

    Sigman, Michael E.; Dindal, Amy B.

    2003-11-11

    Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.

  4. Fabrication of Li 2 TiO 3 spherical microparticles from TiCl 4 by a classical, inorganic sol-gel route; characteristics and tritium release properties

    Microsoft Academic Search

    A. Deptula; T. Olczak; W. ?ada; B. Sartowska; A. G. Chmielewski; C. Alvani; P. L. Carconi; A. Di Bartolomeo; F. Pierdominici; S. Casadio

    2002-01-01

    Medium sized spherical particles of Li2TiO3 (with diameters below 100 µm) can be fabricated by a classical, inorganic sol-gel process, from commercially available TiCl4. Elaborated process consists of the following main steps: (1) dissolving of TiCl4 in concentrated aqueous HCl; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of

  5. Aqueous colloidal sol–gel route to synthesize nanosized ceria-doped titania having high surface area and increased anatase phase stability

    Microsoft Academic Search

    Pradeepan Periyat; K. V. Baiju; P. Mukundan; P. Krishna Pillai; K. G. K. Warrier

    2007-01-01

    Nanocrystalline sol–gel derived titania doped with ceria (1, 2, 5 and 10-mole%) has been prepared from titanyl oxysulphate.\\u000a The titania doped with 5-mole% CeO2 after calcining to 500 ?C, possesses specific surface area of 97 m2 g?1 and has anatase phase stability up to 900 ?C. Moreover it retains a surface area of 37 m2 g?1 at 700 ?C. In comparison, the undoped calcined material has anatase

  6. Sol-gel route to synthesis of microporous ceramic membranes: Preparation and characterization of microporous TiO[sub 2] and ZrO[sub 2] xerogels

    Microsoft Academic Search

    Q. Xu; M. A. Anderson

    1994-01-01

    This paper focuses on the preparation and characterization of pure TiO[sub 2] and ZrO[sub 2] xerogels. The preparation method is based on a sol-gel technique using metal tert-amyloxides as precursors to produce nano-sized metal oxide particles which are subsequently packed in a gelation process, eventually resulting in microporous xerogels. The unsupported TiO[sub 2]and ZrO[sub 2] xerogels produced in this manner

  7. Sol–gel route of synthesis of nanoparticles of MgFe 2O 4 and XRD, FTIR and VSM study

    Microsoft Academic Search

    A. Pradeep; P. Priyadharsini; G. Chandrasekaran

    2008-01-01

    Nanoparticles of MgFe2O4 are synthesized using sol–gel autocombustion method. Structural studies are carried out using X-ray diffraction (XRD). The XRD pattern of MgFe2O4 provides information about single-phase formation of spinel structure with cubic symmetry. The grain size and lattice constant are obtained using XRD data. The cation distribution is also proposed theoretically. The change in site preference of cations in

  8. Effect of Co substitution on the structural and optical properties of ZnO nanoparticles synthesized by sol–gel route

    Microsoft Academic Search

    Mohd Arshad; Ameer Azam; Arham S. Ahmed; S. Mollah; Alim H. Naqvi

    2011-01-01

    Co doped ZnO nanoparticles were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDAX), UV–Visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the formation of single phase structure of all samples which was further supported by FTIR data. With the increase in Co concentration from 0%

  9. Bioactive glass-ceramic coatings prepared by pulsed laser deposition from RKKP targets (sol-gel vs melt-processing route)

    SciTech Connect

    Rau, J.V., E-mail: giulietta.rau@ism.cnr.it [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Teghil, R. [Universita della Basilicata, Dipartimento di Chimica 'A.M. Tamburro', Via dell'Ateneo Lucano, 10-85100 Potenza (Italy) [Universita della Basilicata, Dipartimento di Chimica 'A.M. Tamburro', Via dell'Ateneo Lucano, 10-85100 Potenza (Italy); CNR-IMIP U.O.S. di Potenza, Zona Industriale di Tito scalo (PZ) (Italy); Fosca, M. [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy) [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Universita di Roma 'La Sapienza', Dipartimento di Chimica, Piazzale Aldo Moro, 5-00185 Rome (Italy); De Bonis, A. [Universita della Basilicata, Dipartimento di Chimica 'A.M. Tamburro', Via dell'Ateneo Lucano, 10-85100 Potenza (Italy) [Universita della Basilicata, Dipartimento di Chimica 'A.M. Tamburro', Via dell'Ateneo Lucano, 10-85100 Potenza (Italy); CNR-IMIP U.O.S. di Potenza, Zona Industriale di Tito scalo (PZ) (Italy); Cacciotti, I.; Bianco, A. [Universita di Roma 'Tor Vergata', Dipartimento di Ingegneria Industriale, UR INSTM 'Roma Tor Vergata', Via del Politecnico, 1-00133 Rome (Italy)] [Universita di Roma 'Tor Vergata', Dipartimento di Ingegneria Industriale, UR INSTM 'Roma Tor Vergata', Via del Politecnico, 1-00133 Rome (Italy); Albertini, V. Rossi [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy)] [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Caminiti, R. [Universita di Roma 'La Sapienza', Dipartimento di Chimica, Piazzale Aldo Moro, 5-00185 Rome (Italy)] [Universita di Roma 'La Sapienza', Dipartimento di Chimica, Piazzale Aldo Moro, 5-00185 Rome (Italy); Ravaglioli, A. [Parco Torricelli delle Arti e delle Scienze, Via Granarolo, 64-48018 Faenza (Ra) (Italy)] [Parco Torricelli delle Arti e delle Scienze, Via Granarolo, 64-48018 Faenza (Ra) (Italy)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Bioactive glass-ceramic coatings for bone tissue repair and regeneration. Black-Right-Pointing-Pointer Pulsed Lased Deposition allowed congruent transfer of target composition to coating. Black-Right-Pointing-Pointer Target was prepared by sol-gel process suitable for compositional tailoring. Black-Right-Pointing-Pointer Titanium, widely used for orthopaedics and dental implants, was used as substrate. Black-Right-Pointing-Pointer The physico-chemical properties of the prepared coatings are reported. -- Abstract: The deposition of innovative glass-ceramic composition (i.e. RKKP) coatings by Pulsed Lased Deposition (PLD) technique is reported. RKKP was synthesised following two methodologies: melt-processing and sol-gel, the latter being particularly suitable to tailor the compositional range. The PLD advantage with respect to other deposition techniques is the congruent transfer of the target composition to the coating. The physico-chemical properties of films were investigated by Scanning Electron and Atomic Force Microscopies, Fourier Transform Infrared Spectroscopy, Angular and Energy Dispersive X-ray Diffraction, and Vickers microhardness. The deposition performed at 12 J/cm{sup 2} and 500 Degree-Sign C allows to prepare crystalline films with the composition that replicates rather well that of the initial targets. The 0.6 {mu}m thin melt-processing RKKP films, possessing the hardness of 25 GPa, and the 4.3 {mu}m thick sol-gel films with the hardness of 17 GPa were obtained.

  10. TPR, TPO, and TPD examinations of Cu0.15Ce0.85O(2-y) mixed oxides prepared by co-precipitation, by the sol-gel peroxide route, and by citric acid-assisted synthesis.

    PubMed

    Pintar, Albin; Batista, Jurka; Hocevar, Stanko

    2005-05-01

    Temperature-programmed reduction (TPR), oxidation (TPO), and desorption (TPD) studies were performed on three copper-ceria mixed oxide samples having the same nominal composition, Cu0.15Ce0.85O(2-y), but prepared in three different ways: by co-precipitation, the sol-gel peroxide route, and the sol-gel citric acid route. The obtained results reveal that despite a drastic initial drop in specific surface area after consecutive redox cycles, the hydrogen consumption remains constant. This is because CuO is highly dispersed over the surface of CeO2 nanocrystallites and remains highly dispersed even after the agglomeration of CeO2 nanocrystallites in a denser secondary structure. The dispersed CuO is reduced to Cu(0) during the TPR, forming agglomerated metal particles on the surface of partially reduced CeO2. However, after subsequent temperature-programmed oxidation all the Cu(0) is oxidized back into CuO and redispersed over the CeO2 crystallites. PMID:15797417

  11. Citric acid effect on aqueous sol–gel cordierite synthesis

    Microsoft Academic Search

    Celso A Bertran; Nidinalva T da Silva; Gilmar P Thim

    2000-01-01

    Cordierite was synthesized by a simple aqueous sol–gel route. Citric acid action as a chelant for the Al3+ ion, and for controlling phase segregation during the drying and initial thermal treatment of the gel, results in an amorphous precursor that crystallizes to ?-cordierite and spinel. The changes in the ratios of the crystalline phases, formed during dry gel calcination at

  12. Sol–gel-fluorination synthesis of amorphous magnesium fluoride

    Microsoft Academic Search

    J. Krishna Murthy; Udo Gross; Stephan Ruediger; Erhard. Kemnitz; John M. Winfield

    2006-01-01

    The sol–gel fluorination process is discussed for the reaction of magnesium alkoxides with HF in non-aqueous solvents to give X-ray amorphous nano-sized magnesium fluoride with high surface areas in the range of 150–350m2\\/g (HS-MgF2). The H2 type hysteresis of nitrogen adsorption–desorption BET-isotherms is indicative for mesoporous solids. A highly distorted structure causes quite high Lewis acidity, shown by NH3 temperature-programmed

  13. Structural, magnetic and Mössbauer studies of (BiFeO3)0.7-(SrFe12O19)0.3 nanocomposite prepared by a sol-gel route

    NASA Astrophysics Data System (ADS)

    Das, A.; Roychowdhury, A.; Pati, S. P.; Bandyopadhyay, S.; Das, D.

    2014-04-01

    The nanocomposite (BiFeO3)0.7-(SrFe12O19)0.3 has been prepared by a sol-gel route and characterized by XRD, TEM, TGA/DTA, dc magnetization and 57Fe Mössbauer spectroscopy. The hyperfine parameters obtained from Mössbauer spectroscopy indicate formation of pure hexaferrite phase of SrFe12O19 (SRF) in the nanocomposite (NC). The NC exhibits typical hysteresis loops with significantly altered magnetization parameters (saturation magnetization, coercivity and remnant magnetization) in comparison with that of the pristine SRF and BiFeO3 (BFO) nanoparticles (NPs). The ZFC-FC curves show a divergence in low temperature region which confirms the irreversible character of magnetization.

  14. Synthesis of Organic-Inorganic Hybrid Particles by Sol-Gel Chemistry

    Microsoft Academic Search

    Anna Arkhireeva; John N. Hay; Miguel Manzano; Helen Masters; Wilberforce Oware; Steve J. Shaw

    2004-01-01

    The synthesis of ORganically MOdified SILica (ORMOSIL) particles has been carried out using both the hydrolytic and non-hydrolytic sol-gel routes. The hybrid (nano)composites are organically modified with an alkyl or aryl group covalently bonded to silicon. Hybrids have been synthesised in an aqueous sol-gel process by a modified Stöber route, producing spherical nanoparticles with diameters in the range 50–300 nm.

  15. Sol-gel chemistry by ring-opening polymerization

    SciTech Connect

    RAHIMIAN,KAMYAR; LOY,DOUGLAS A.

    2000-02-07

    Sol-gel processing of materials is plagued by shrinkage during polymerization of the alkoxide monomers and processing (aging and drying) of the resulting gels. The authors have developed a new class of hybrid organic-inorganic materials based on the solventless ring-opening polymerization (ROP) of monomers bearing the 2,2,5,5-tetramethyl-2,5-disilaoxacyclopentyl group, which permits them to drastically reduce shrinkage in sol-gel processed materials. Because the monomers are polymerized through a chain growth mechanism catalyzed by base rather than the step growth mechanism normally used in sol-gel systems, hydrolysis and condensation products are entirely eliminated. Furthermore, since water is not required for hydrolysis, an alcohol solvent is not necessary. Monomers with two disilaoxacyclopentyl groups, separated by a rigid phenylene group or a more flexible alkylene group, were prepared through disilylation of the corresponding diacetylenes, followed by ring closure and hydrogenation. Anionic polymerization of these materials, either neat or with 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane as a copolymer, affords thermally stable transparent gels with no visible shrinkage. These materials provide an easy route to the introduction of sol-gel type materials in encapsulation of microelectronics, which they have successfully demonstrated.

  16. Surfactant-assisted route to synthesize well-aligned ZnO nanorod arrays on sol-gel-derived ZnO thin films.

    PubMed

    Dev, Apurba; Panda, Subhendu K; Kar, Soumitra; Chakrabarti, Supriya; Chaudhuri, Subhadra

    2006-07-27

    Anisotropic growth of ZnO nanorod arrays on ZnO thin films was achieved at a temperature of 90 degrees C by a surfactant-assisted soft chemical approach with control over size and orientation. ZnO thin films with c-axis preferred orientation had been achieved by the sol-gel technique. Lengths, diameters, and the degree of alignment of the ZnO nanorods were controlled by changing the experimental parameters. It was observed that the surfactant was essential to restrict the lateral growth of the nanorods, whereas the pH level of the reaction medium controlled the length of the nanorods. On the other hand, the orientation of the nanorods depended on the crystalline orientation of the film as well as the pH of the reaction medium. Room-temperature photoluminescence studies revealed that the ZnO nanorods with the best alignment exhibited the best emission property. The ZnO nanorods exhibited a strong UV emission peak at approximately 3.22 eV, ascribed to the band-edge emission. The field emission studies of the well-aligned nanorod arrays exhibited a low turn-on field of 1.7 V/microm to get an emission current density of 0.1 microA/cm(2). PMID:16854131

  17. Phase and electrical properties of PZT thin films embedded with CuO nano-particles by a hybrid sol-gel route

    NASA Astrophysics Data System (ADS)

    Sreesattabud, Tharathip; Gibbons, Brady J.; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

    2013-07-01

    Pb(Zr0.52Ti0.48)O3 or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 wt. %) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrate using a spin-coating technique. The influence of CuO nano-particles' dispersion on the phase of PZT thin films was investigated. XRD results showed a perovskite phase in all films. At the CuO concentration of 0.4-1 wt. %, a second phase was observed. The addition of CuO nano-particles affected the orientation of PZT thin films. The addition was also found to reduce the ferroelectric properties of PZT thin films. However, at 0.2 wt. % CuO concentration, the film exhibited good ferroelectric properties similar to those of PZT films. In addition, the fatigue retention properties of the PZT/CuO system was observed, and it showed 14% fatigue at 108 switching bipolar pulse cycles while the fatigue in PZT thin films was found to be 17% at the same switching bipolar pulse cycles.

  18. Electrochemical impedance studies of sol–gel based ceramic coatings systems in 3.5% NaCl solution

    Microsoft Academic Search

    Abdel Salam Hamdy; D. P. Butt; A. A. Ismail

    2007-01-01

    Ceramic coatings based on salts like vanadia, ceria, silica and molybdate prepared by sol–gel route are proposed as alternatives to the process involving toxic hexavalent chromate. The surface of the specimens were modified under different conditions and then dipped in a corresponding salt solution prepared via sol–gel method. Electrochemical impedance spectroscopy (EIS) and polarization measurements have been used to evaluate

  19. Encapsulation of enzymes and cells in sol-gel matrices for biosensor applications

    NASA Astrophysics Data System (ADS)

    Singh, Anup K.; Gupta, Alok; Mulchandani, Ashok; Chen, Wilfred; Bhatia, Rimple B.; Schoeniger, Joseph S.; Ashley, Carol S.; Brinker, C. J.

    1999-12-01

    Porous silicate materials made by low temperature sol-gel process are promising host matrices for encapsulation of biomolecules. Their mechanical strength, chemical inertness, hydrophilic nature, and above all, their optical transparency makes them an exciting platform for development of biosensors. To date, researchers have focused on sol-gel routes using alkoxides for encapsulation of biomolecules. However, formation of alcohol as a byproduct is an undesired complication as it can have detrimental effect on the activity of entrapped biomolecules. We have developed a novel sol-gel process to encapsulate biological molecules (such as enzymes, antibodies and cells) that uses neutral pH, room temperature, and does not generate alcohol as a byproduct. The process uses sodium silicate as precursor and is carried out in two steps--preparation of a low pH silicate sol followed by gelation at neutral pH in a buffer containing biomolecules. We developed a novel homogeneous immunoassay for 2,4,6-trinitrotoluene (TNT), and have encapsulated the immunoassay reagents in sol-gel matrices to product dispersible biosensors for the detection of TNT. Using the sol-gel doped with immunoassay reagents, we can detect TNT at low ppm levels. We also report encapsulation of E. Coli cells expressing the enzyme organophosphorus hydrolase on the cell surface in sol-gel matrices. The cell- doped sol-gel material can be used to develop biosensors for detection of organophosphates.

  20. Sol–gel synthesis and characterization of hydroxyapatite nanorods

    Microsoft Academic Search

    Sanosh Kunjalukkal Padmanabhan; Avinash Balakrishnan; Min-Cheol Chu; Yong Jin Lee; Taik Nam Kim; Seong-Jai Cho

    2009-01-01

    In the present study hydroxyapatite (HA) nano-hexagonal rods with 70–90nm diameter and 400–500nm length are synthesized using a simple sol–gel route with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors respectively. Deionized water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH=9. After aging, the HA gel was dried

  1. Composite sol-gel ceramics

    NASA Astrophysics Data System (ADS)

    Yang, Quanzu

    1999-11-01

    The fundamental goal of the present study was to develop an understanding of the mechanisms of dispersion, gelation, drying, interfacial bonding and densification of composite sol-gel (CSG) ceramics. The general applied objective was to fabricate high performance CSG ceramics and to produce novel, non-permeable, adherent CSG coatings on stainless steel substrates for high temperature corrosion and wear protection. The properties of the alumina sols and CSG were studied by measuring viscosity, conductivity, ionic strength, and pH of the sol. The dispersion and stability of ceramic particles in alumina sols were investigated by measuring particle size distributions, measuring zeta potentials, and calculating the interaction energy according to DLVO theory. The CSG technology has been developed to fabricate high performance engineering composite ceramics and coatings through dispersing ceramic fillers (alumina, zirconia, SiC) into alumina sols, gelcasting, drying, and pressureless sintering. A sintering model for CSG was developed and validated by experiment results. The model was then used successfully to predict sinterability and to optimize the processing technologies of CSG. The research results indicate that hydrated alumina sols can be used as a sintering and dispersion additive for alumina-based ceramics. The sol-gel matrix provides fast diffusion paths for mass transport during sintering CSG. Dispersion of alumina and SiC particles is substantially improved in alumina sols, as compared to pure water of similar acidity, e.g. the average agglomerate size is decreased by at least 50%. For alumina/alumina CSG ceramics sintered at 1400°C, the microhardness is 20 GPa and porosity is less than 1 vol%. The CSG composite with composition of 50vol%SiC-50vol%Al2O 3 has been sintered successfully to full densification and microhardness of 22.9 GPa. A novel process for ceramic coatings on the metallic substrates has been developed successfully by combining chemical bonding and CSG technologies. Non-permeable, crack-free, thick ceramic coatings (2--600 mum) on the substrates were fabricated by spraying and dipping, followed by low temperature (500--600°C) sintering. The correlations between the processing methods, microstructure, and mechanical properties of CSG coatings were investigated by varying the preparation methods, studying morphology, and measuring mechanical properties of the ceramics. The chemically bonded CSG coatings have the best performance. The bonding strength between the substrates and coatings is about 42 MPa, and the surface microhardness of the coatings is about 6.5 GPa.

  2. Sol-gel deposited electrochromic coatings

    SciTech Connect

    Ozer, N.; Lampert, C.M.

    1995-06-01

    Electrochromic devices have increasing application in display devices, switchable mirrors and smart windows. A variety of vacuum deposition technologies have been used to make electrochromic devices. The sol- gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO[sub 3], V[sub 2]O[sub 5], TiO[sub 2], Nb[sub 2]O[sub 5], and NiO[sub x].

  3. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, Carol S. (Albuquerque, NM); Reed, Scott T. (Albuquerque, NM)

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  4. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, C.S.; Reed, S.T.

    1988-01-26

    An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  5. Sol-gel-based poliovirus-1 detector.

    PubMed

    Zolkov, Chen; Avnir, David; Armon, Robert

    2009-02-01

    Hybrid sol-gel films were used to grow Buffalo Green Monkey kidney cell tissues, which were used for poliovirus-1 detection. It is shown that the sol-gel approach allows cutting the standard EPA procedure from 48 to 24h of detection time; that better visualization of the plaques is obtained; that a variety of stains, including fluorescence, can be used; and that the shelf life of the resulting plaques system is well over a year. PMID:18996413

  6. Nonaqueous sol–gel synthesis of nano-structured metal fluorides

    Microsoft Academic Search

    Stephan Rüdiger; Udo Groß; Erhard Kemnitz

    2007-01-01

    This review summarises the progress, achieved in the last 5 years, in the field of synthesis of nano-structured metal fluorides. The main focus is laid on the non-aqueous sol–gel-synthesis, which is opening a wide window toward nanoscopic metal fluorides with properties remarkably different from that of crystalline metal fluorides. Based on examples of binary as well as complex metal fluorides

  7. The Influence of Microgravity on Silica Sol-Gel Formation

    NASA Technical Reports Server (NTRS)

    Sibille, L.; Smith, D. D.; Cronise, R.; Hunt, A. J.; Wolfe, D. B.; Snow, L. A.; Oldenberg, S.; Halas, N.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We discuss space-flight experiments involving the growth of silica particles and gels. The effect of microgravity on the growth of silica particles via the sol-gel route is profound. In four different recipes spanning a large range of the parameter space that typically produces silica nanoparticles in unit-gravity, low-density gel structures were instead formed in microgravity. The particles that did form were generally smaller and more polydisperse than those grown on the ground. These observations suggest that microgravity reduces the particle growth rate, allowing unincorporated species to form aggregates and ultimately gel. Hence microgravity favors the formation of more rarefied structures, providing a bias towards diffusion-limited cluster-cluster aggregation. These results further suggest that in unit gravity, fluid flows and sedimentation can significantly perturb sol-gel substructures prior to gelation and these deleterious perturbations may be "frozen" into the resulting microstructure. Hence, sol-gel pores may be expected to be smaller, more uniform, and less rough when formed in microgravity.

  8. Synthesis of Tube-Like PZT Nanostructures by Sol-Gel Process

    NASA Astrophysics Data System (ADS)

    Acharya, S. A.; Singh, K.

    2011-11-01

    In the present work, we report the synthesis of PZT in tubes-like nanostructure by microwave-assisted sol-gel route. According to our knowledge, this is the first report on tubes-like PZT, were obtained by microwave-assisted sol-gel route. To understand the effect of microwave heating on the synthesis, the same experiment was repeated by using conventional way of heating. Round shape nanoparticles of PZT were obtained by the conventional sol-gel route. The crystallization behaviors of the tubes and nanoparticles of PZT are confirmed by XRD. The structural morphologies of the PZT sample are observed by SEM and TEM. The thermal decomposition characteristics of the gel are identified by DTA and TGA. The molecular structures are investigated by FTIR. A pure pervoskite PZT powders were obtained after having been annealed tubes-like structure at 650 °C and NPs at 750 °C for 3 hr.

  9. Toward sol-gel-based sensors

    SciTech Connect

    Jordan, J.D.; Ingersoll, C.M.; Dunbar, R.A. [State Univ. of New York, Buffalo, NY (United States)] [and others

    1995-12-31

    Advances in biotechnology have produced a variety of antibodies and other biomolecules that possess selective recognition capabilities. Current techniques for the immobilization of these biomolecules typically involve multistep derivatization of a primary substrate, which is labor intensive and often requires large volumes of costly reagents. Further, these immobilization chemistries often adversely affect the characteristic properties of the protein (e.g., the binding affinity). As a result, the need for fast, accurate, inexpensive, and simple to operate diagnostic assays escalates. Because of their room temperature processing, transparency, inertness, and tunable pore structure, sol-gel-derived composites represent promising chemical and biosensing platforms. To date, many researchers have entrapped proteins and enzymes in sol-gel monoliths, and found that they retain some of their native properties. Our group first reported on the affinity of a sol-gel entrapped antibody. However, although these biogel monoliths were promising, analyte diffusion through the monolith matrix is slow, resulting in long response times. Thus, it is clear that the next level of sol-gel-derived biosensor must depend on thin film technology. In the current work, the affinity of fluorescein entrapped within a sol-gel derived thin film for the anti fluorescent hapten, 5- (and 6-)-carboxy 4{prime}, 5{prime}-dimethylfluorescein, is investigated. A novel film preparation technique will be introduced, and the response and response times of these films as a function of processing and storage conditions will be discussed.

  10. Chemical modification of TiO2 by H2PO{4/-}/HPO{4/2-} anions using the sol-gel route with controlled precipitation and hydrolysis: enhancing thermal stability

    NASA Astrophysics Data System (ADS)

    Elghniji, Kais; Saad, Mohamed El Khames; Araissi, Manel; Elaloui, Elimame; Moussaoui, Younes

    2014-12-01

    Two titanium phosphate materials (T p P and T h P) have been successfully synthesized by sol-gel route with controlled precipitation and hydrolysis. The T p P material was obtained from the reaction between precipitated titania and phosphate buffer solution H2PO{4/-} /HPO{4/2-} (pH = 7.3). The T p P material was prepared through hydrolysis of titanium in the presence of H2PO{4/-}/HPO{4/2}. The probable state of the phosphate anions in titania framework and their effect on the anatase-to-rutile transformation were characterized by ICP-AES, DTA-TG, 31P NMR, FT-IR, and Raman analysis HRTEM/SEM. FT-IR and 31P NMR analyses of titanium phosphate T p P calcined at low temperature showed that the phosphate species existed not only as Ti-O-P in the bulk TiO2 but also as amorphous titanium phosphates, including bidentate Ti(HPO4)2 and monodentate Ti(H2PO4)4. Increased calcination temperature only gave an enrichment of bidentate structure on the titania surface. For the T p P material, H2PO{4/-}/HPO{4/2-} anions were introduced into the initial solution, before precipitation, what promoted their lattice localization. At high temperatures, all the phosphorus inside the bulk of TiO2 migrated to the surface. The Raman analysis of both samples showed that the bidentate phosphates increased the temperature of the anatase-to-rutile phase transformation to more than 1000 °C with the formation of well crystalline TiP2O7 phase. This phenomenon was more evident for T p P sample.

  11. Sol-Gel Synthesis of Nano-Scaled BaTiO3, BaZrO3 and BaTi0.5Zr0.5O3 Oxides via Single-Source Alkoxide Precursors and Semi-Alkoxide Routes

    Microsoft Academic Search

    Michael Veith; Sanjay Mathur; Nicolas Lecerf; Volker Huch; Timo Decker; Horst P. Beck; Wolfgang Eiser; Robert Haberkorn

    2000-01-01

    Sol-gel synthesis of nano-sized BaTiO3, BaZrO3 and BaTi0.5Zr0.5O3 ceramics using alkoxide and semi-alkoxide routes has been investigated and the pervoskites obtained have been compared with respect to crystallisation temperature, crystallite size and compositional purity. Heterometal alkoxides containing two (for BaTiO3 and BaZrO3) and three (for BaTi0.5Zr0.5O3) different metals were used as single-source precursors in the alkoxide route while semi-alkoxide synthesis

  12. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M. (Albuquerque, NM)

    1993-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  13. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, J.M.

    1993-04-20

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  14. Hybrid sol-gel optical materials

    DOEpatents

    Zeigler, John M. (Albuquerque, NM)

    1992-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  15. Neutron detector using sol-gel absorber

    DOEpatents

    Hiller, John M. (Oak Ridge, TN); Wallace, Steven A. (Oak Ridge, TN); Dai, Sheng (Knoxville, TN)

    1999-01-01

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  16. Sintering effects on dielectric properties of Zn-doped CaCu3Ti4O12 ceramic synthesized by modified sol-gel route

    NASA Astrophysics Data System (ADS)

    Singh, Laxman; Rai, U. S.; Rai, Alok Kumar; Mandal, K. D.

    2013-01-01

    CaCu2.90Zn0.10Ti4O12 ceramic was synthesized by a novel semi-wet route and calcined at 800°C in air for 8 h. The obtained powder was divided into three parts and sintered in air at 950°C for 6 h, 8 h, and 12 h, separately. XRD results confirmed the single phase formation of all the sintered samples with similar cubic structure of CaCu3Ti4O12 (CCTO). Scanning electron micrographs of the CaCu2.9Zn0.1Ti4O12 ceramic sintered for 6 h shows bimodal grain size distribution. Increasing the sintering time significantly promotes the grain growth and microstructural densification. The sintering duration was found to have tremendous influence on microstructure and dielectric properties of CaCu2.90Zn0.10Ti4O12 ceramic. The CaCu2.9Zn0.1Ti4O12 ceramic sintered for 12 h exhibited high dielectric constant ? r ˜ 5971 at 1 kHz and room temperature. It is found that ? r is independent at high frequency and weakly dependent on temperature.

  17. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  18. Sol-Gel Derived Hafnia Coatings

    NASA Technical Reports Server (NTRS)

    Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

  19. MECHANICAL PROPERTY CHARACTERIZATION OF SOL-GEL DERIVED NANOMATERIALS

    E-print Network

    Brinker, C. Jeffrey

    MECHANICAL PROPERTY CHARACTERIZATION OF SOL-GEL DERIVED NANOMATERIALS USING AN ACOUSTIC WAVE;#12;For my Terra........ iii #12;MECHANICAL PROPERTY CHARACTERIZATION OF SOL-GEL DERIVED NANOMATERIALS, New Mexico November 2006 #12;Mechanical Property Characterization of Sol-gel Derived Nanomaterials

  20. Process ceramic fibers by Sol-Gel

    SciTech Connect

    Fernandez de, M.E.P.; Kang, Cheolho; Mangonon, P.L.

    1993-09-01

    The Sol-Gel process may transform the materials of construction chemical engineers make and use--thin films, fibers, and powders. The advantage of the Sol-Gel technology is the ability to produce high purity products at low temperatures. For example, silica film is used to passivate integrated circuits. To achieve this, the native silicon substrate now is oxidized at about 1,000C for a short period of time. At this temperature, diffusion of the dopant atoms may be induced to alter the electronic properties of the chip. In contrast, the film application using Sol-Gel may be done at 400-600C. Another example is the interest in ceramic fibers to incorporate in fiber-reinforced ceramic matrix composite materials. The latter is considered an enabling technology for the 21st Century high-speed civil transport plane (NASA) and the National Aerospace plane (X-30). Glass and ceramic fibers have been prepared conventionally by drawing or blowing a high temperature melt through an orifice. The traditional process requires the conversion of the raw materials into a homogeneous, high temperature melt, which makes producing fibers based on materials having high melting points or materials that are immiscible in the liquid state difficult. The Sol-Gel process applied to the production of fibers offers an advantage over the conventional method, since the fibers are drawn from the Gel at low temperatures and then are converted to glass or ceramics by heating the fibers at high temperatures, T[lt]600C. Also by using this technique there is the potential to produce glasses of new compositions with high purity and homogeneity. This article will briefly discuss the polymerization aspect of the Sol-Gel process. The chemical, physical, and rheological aspects of the process to produce the desired product will be discussed.

  1. Transparent ion-conducting ceria-zirconia films made by sol–gel technology

    Microsoft Academic Search

    X Luo; B Zhu; C Xia; G. A Niklasson; C. G Granqvist

    1998-01-01

    Films of Ce–Zr oxide were made by sol–gel deposition according to three different routes. Cyclic voltammetry showed that Li+ intercalation\\/deintercalation took place if the Ce content was sufficient. The films had a high transmittance for visible light. They are of interest as counter electrodes in electrochromic smart windows.

  2. High temperature spectral hole burning on porphyrins grafted to sol-gel matrices

    Microsoft Academic Search

    A. V. Veret-Lemarinier; J. P. Galaup; A. Ranger; F. Chaput; J. P. Boilot

    1995-01-01

    Protoporphyrin IX is grafted by two chemical bonds to a rigid Si-O-Si network prepared by using the sol-gel route. Efficient hole burning is observed in hybrid organic-inorganic matrices. Persistent spectral holes are still burnt at 120 K.

  3. Sol-Gel Growth of Vanadium Dioxide

    Microsoft Academic Search

    Kenneth Richard Speck

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using ^{51}V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard

  4. Characterization of sol–gel-prepared nanoferrites

    Microsoft Academic Search

    M. K. Shobana; S. Sankar

    2009-01-01

    Spinel Co1?xMnxFe2O4 nanoparticles were prepared by the sol–gel combustion technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and vibration sample magnetometer (VSM) studies have been carried out in order to understand the temperature dependence of their properties. It is observed that the high concentration of Mn2+ substituted into CoFe2O4 tends to reduce the particle size. Furthermore, the influence of Mn

  5. Sol-gel growth of vanadium dioxide

    SciTech Connect

    Speck, K.R.

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using {sup 51}V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs.

  6. Er3+-activated photonic structures fabricated by sol-gel and rf-sputtering techniques

    NASA Astrophysics Data System (ADS)

    Ferrari, M.; Alombert-Goget, G.; Armellini, C.; Berneschi, S.; Bhaktha, S. N. B.; Boulard, B.; Brenci, M.; Chiappini, A.; Chiasera, A.; Duverger-Arfuso, C.; Féron, P.; Gonçalves, R. R.; Jestin, Y.; Minati, L.; Moser, E.; Nunzi Conti, G.; Pelli, S.; Rao, D. N.; Retoux, R.; Righini, G. C.; Speranza, G.

    2009-05-01

    The realization of photonic structures operating at visible and near infrared frequencies is a highly attractive scientific and technological challenge. Since optical fiber innovation, a huge of activity has been performed leading to interesting results, such as optical waveguides and planar lightwave circuits, microphotonic devices, optical microcavities, nanowires, plasmonic structures, and photonic crystals. These systems have opened new possibilities in the field of both basic and applied physics, in a large area covering Information Communication Technologies, Health and Biology, Structural Engineering, and Environment Monitoring Systems. Several materials and techniques are employed to successfully fabricate photonic structures. Concerning materials, Er3+-activated silica-based glasses still play an important role, although recently interesting results have been published about fluoride glass-ceramic waveguides. As far as regards the fabrication methods sol-gel route and rf sputtering have proved to be versatile and reliable techniques. In this article we will present a review of some Er3+-activated photonic structures fabricated by sol gel route and rf sputtering deposition. In the discussion on the sol-gel approach we focus our attention on the silica-hafnia binary system presenting an overview concerning fabrication protocols and structural, optical and spectroscopic assessment of SiO2-HfO2 waveguides activated by Er3+ ions. In order to put in evidence the reliability and versatility of the sol-gel route for photonics applications four different confined structures are briefly presented: amorphous waveguides, coated microspheres, monolithic waveguide laser, and core-shell nanospheres. As examples of rf sputtering technique, we will discuss Er3+-activated silica-hafnia and silica-germania waveguides, the latter system allowing fabrication of integrated optics structures by UV photo-imprinting. Finally, two examples of photonic crystal structures, one prepared by sol-gel process and the other one fabricated by rf sputtering deposition, will be illustrated.

  7. Orientation of PZT thin films prepared by sol-gel techniques

    Microsoft Academic Search

    Jinrong Cheng; Laiqing Luob; Zhongyan Mengb

    2000-01-01

    The authors study the crystal orientation of PZT thin films fabricated by using sol-gel routes on (111) Pt\\/Ti\\/SiO2\\/Si substrates. The crystallization of PZT thin films was performed at 650°C for 30 minutes by using rapid thermal annealing (RTA) routes. XRD analysis was used to identify the film orientation. The morphology was examined using SEM. The different ratios of Zr\\/Ti, the

  8. Synthesis of nanocrystalline photocatalytic TiO 2 thin films and particles using sol–gel method modified with nonionic surfactants

    Microsoft Academic Search

    Hyeok Choi; Elias Stathatos; Dionysios D. Dionysiou

    2006-01-01

    A simple sol–gel route has been developed for the preparation of nanocrystalline photocatalytic TiO2 thin films and particles at 500 °C. The synthesis involved a novel chemistry method employing nonionic surfactant molecules as a pore directing agent along with acetic acid-based sol–gel route without direct addition of water molecules. This study investigated the effect of surfactant type and concentration on

  9. Synthesis of highly textured superconducting NdBa 2 Cu 3 O 7-y thin films using an aqueous inorganic sol-gel dip coating technique

    Microsoft Academic Search

    B. Schoofs; T. Mouganie; B. A. Glowacki; V. Cloet; S. Hoste; I. Van Driessche

    2006-01-01

    In general, the sol-gel method is a very attractive route for ceramic synthesis because it permits direct fabrication of multi-component ceramics in different configurations without powder intermediates. This diversity, in which materials can be formed, has made the sol-gel method an important synthesis route in several domains of research. For (RE)Ba2Cu3O7-y superconducting thin film development, chemical solution deposition (CSD) techniques

  10. Synthesis of highly textured superconducting NdBa2Cu3O7-y thin films using an aqueous inorganic sol-gel dip coating technique

    Microsoft Academic Search

    B Schoofs; T Mouganie; B A Glowacki; V Cloet; S Hoste; I Van Driessche

    2006-01-01

    In general, the sol-gel method is a very attractive route for ceramic synthesis because it permits direct fabrication of multi-component ceramics in different configurations without powder intermediates. This diversity, in which materials can be formed, has made the sol-gel method an important synthesis route in several domains of research. For (RE)Ba2Cu3O7-y superconducting thin film development, chemical solution deposition (CSD) techniques

  11. Beta zeolite supported sol-gel TiO2 materials for gas phase photocatalytic applications.

    PubMed

    Lafjah, Mama; Djafri, Fatiha; Bengueddach, Abdelkader; Keller, Nicolas; Keller, Valérie

    2011-02-28

    Beta zeolite supported sol-gel TiO(2) photocatalytic materials were prepared according to a sol-gel route in which high specific surface area Beta zeolite powder was incorporated into the titanium isopropoxide sol during the course of the sol-gel process. This led to an intimate contact between the zeolite surface and the TiO(2) precursors, and resulted in the anchorage of large amounts of dispersed TiO(2) nanoparticles and in the stabilization of TiO(2) in its anatase form, even for high TiO(2) wt. contents and high calcination temperatures. Taking the UV-A photocatalytic oxidation of methanol as gas phase target reaction, high methanol conversions were obtained on the Beta zeolite supported TiO(2) photocatalysts when compared to bulk sol-gel TiO(2), despite lower amounts of TiO(2) within the photoactive materials. The methanol conversion was optimum for about 40 wt.% TiO(2) loading and calcination temperatures of 500-600°C. PMID:21177024

  12. Multiwalled carbon nanotubes embedded in sol–gel derived TiO 2 matrices and their use as room temperature gas sensors

    Microsoft Academic Search

    M. Sánchez; R. Guirado; M. E. Rincón

    2007-01-01

    Sol–gel TiO2\\/Multiwall Carbon Nanotubes composites obtained by the Ti-isopropoxide route are reported as room temperature sensitive coatings.\\u000a The effect of functionalizing the carbon nanotubes in strong oxidizing acids prior to the sol–gel synthesis is studied in\\u000a the detection of acetone (CH3COCH3) and ammonia (NH3). Although, mixed oxide phases were found in the sol–gel oxide and composites, sensing was highly reproducible

  13. Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

    ERIC Educational Resources Information Center

    Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

    2010-01-01

    This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…

  14. AFM examination of sol-gel matrices doped with photosensitizers

    Microsoft Academic Search

    KATARZYNA WYSOCKA; AGNIESZKA ULATOWSKA-JAR?A; JOANNA BAUER; BOGDAN SAVU; GEORGE STANCIU; HALINA PODBIELSKA

    Various compounds may be entrapped into the sol-gel materials, including the photosensitive agents. The nanostructure of the final material depends on the matrix itself, as well as on the structural properties of doped compound. In this work, sol-gel matrices were produced from silica based precursor tetraethoxysilan (TEOS) in the form of single layers deposited on microscopic glasses. Materials were produced

  15. Synthesis and characterization of La 0.8 Sr 0.2 Co 0.5 Fe 0.5 O 3±? nanopowders by microwave assisted sol–gel route

    Microsoft Academic Search

    Shiming Liu; Xiaoliang Qian; Jianzhong Xiao

    2007-01-01

    Nano-crystalline La0.8Sr0.2Co0.5Fe0.5O3?? powder has been successfully synthesized by microwave assisted sol–gel (MWSG) method. The decomposition and crystallization\\u000a behavior of the gel-precursor was studied by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis.\\u000a From the result of FT-IR and X-ray diffraction patterns, it is found that a perovskite La0.8Sr0.2Co0.5Fe0.5O3?? was formed by irradiating the precursor at 700 W for 3 min,

  16. Dense PZT thick films derived from sol-gel based nanocomposite process

    Microsoft Academic Search

    Zhihong Wang; Weiguang Zhu; Changlei Zhao; Ooi Kiang Tan

    2003-01-01

    Dense, crack-free piezoelectric thick film integrated on silicon substrate has been the subject of considerable attention in recent years for potential application in microelectro mechanical systems (MEMS). We have proposed a new spin-coating route for this purpose in which films are made from homogenous slurry of sol-gel precursor and nano-sized powders. Commercially available ceramic PZT (53\\/47: Zr\\/Ti) powders are ball

  17. Sol–gel synthesis of pure nano sized ?-tricalcium phosphate crystalline powders

    Microsoft Academic Search

    K. P. Sanosh; Min-Cheol Chu; A. Balakrishnan; T. N. Kim; Seong-Jai Cho

    2010-01-01

    ?-Tricalcium phosphate (?-TCP) nano powders (?80nm) were synthesized using a simple sol–gel route with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for ?-TCP sol preparation and ammonia was used to adjust the pH. After aging, the ?-TCP gel was dried at 40°C and calcined to different temperatures

  18. Segregation effects in sol-gel zirconia-silica materials analyzed through their radial distribution functions

    Microsoft Academic Search

    P. Salas; J. Montoya; V. M. Castaño; R. Rodríguez

    2000-01-01

    A novel method to characterize segregation effects in silica-zirconia materials prepared by the sol-gel method through the\\u000a alkoxide route is reported. These segregation effects were studied by using the Radial Distribution Function obtained from\\u000a the X-ray diffractograms. The information obtained by this technique allows one to predict the spatial distribution of one\\u000a of the oxides into the other as a

  19. Luminescence properties of sol–gel-derived TiO 2:Sm powder

    Microsoft Academic Search

    V. Kiisk; V. Reedo; O. Sild; I. Sildos

    2009-01-01

    Sm-doped TiO2 nanopowder phosphors were prepared by employing a sol–gel route. Thermal treatment crystallizes the powder in anatase phase and leads to a quite efficient (quantum yield ?15%) Sm3+ luminescence with a well-resolved fine structure under optical excitation within the fundamental absorption band of the host. From the PL spectrum and its temperature dependence the energy level scheme of Sm3+

  20. Synthesis and characterization of LiFePO 4 prepared by sol–gel technique

    Microsoft Academic Search

    M. A. E. Sanchez; G. E. S. Brito; M. C. A. Fantini; G. F. Goya; J. R. Matos

    2006-01-01

    LiFePO4 powder was synthesized by means of a new route, using a two step process. In the first step, an intermediate compound was synthesized by the sol–gel method. This precursor compound to LiFePO4 was characterized by thermal analysis (TG\\/DTG and DSC), Mössbauer spectroscopy, Transmission Electronic Microscopy (TEM) and Small Angle Scattering (SAXS). In the second step, the precursor was sintered

  1. Characterization of nanostructured magnetite thin films produced by sol–gel processing

    Microsoft Academic Search

    Ali Erdem Eken; Macit Ozenbas

    2009-01-01

    Nanocrystalline films of magnetite have been prepared by a novel sol–gel route in which, a solution of iron (III) nitrate\\u000a dissolved in ethylene glycol was applied on glass substrates by spin coating. Coating solution showed Newtonian behaviour\\u000a and viscosity was found as 0.0215 Pa.s. Annealing temperature was selected between 291 and 350 °C by DTA analysis in order\\u000a to obtain magnetite films.

  2. Bimetallic colloids of silver and copper in thin films: sol–gel synthesis and characterization

    Microsoft Academic Search

    Ganesh Suyal

    2003-01-01

    A sol–gel route to synthesize thin films containing alloy- and phase separated mixed-colloids of silver (Ag) and copper (Cu) has been developed. Ag–Cu alloy colloids with Ag:Cu molar ratios of 4:1–1:2 in the coatings were obtained by the addition of copper ions stabilized in a pre-hydrolyzed SiO2-sol in the presence of hydroxylamine hydrochloride, to a colloidal silver sol stabilized by

  3. Sol-gel synthesis of protoenstatite

    SciTech Connect

    Jones, S.A.; Burlitch, J.M. [Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry

    1994-12-31

    Protoenstatite, a high-temperature polymorph of enstatite (MgSiO{sub 3}), is generally not stable at room temperature, and is difficult to synthesize. Using a recently developed, hydrogen peroxide assisted, sol-gel synthesis, protoenstatite was synthesized in a form that was stable at room temperature. Its crystallization was strongly dependent on processing conditions, particularly on the manner in which the xerogel was formed and fired. Xerogels prepared by evaporation, spray-drying and freeze-drying were compared by XRD, HTXRD, BET, TG/DTA, and {sup 29}Si NMR methods. When samples were prepared by evaporation or spray-drying, the result was a mixture of polymorphs. Only the freeze-dried precursor yielded protoenstatite at a lower temperature and within a shorter time than any previously reported.

  4. Sol-gel processing of energetic materials

    SciTech Connect

    Tillotson, T.M.; Hrubesh, L.H.; Fox, G.L.; Simpson, R.L.; Lee, R.W.; Swansiger, R.W.; Simpson, L.R.

    1997-08-18

    As part of a new materials effort, we are exploring the use of sol- gel chemistry to manufacture energetic materials. Traditional manufacturing of energetic materials involves processing of granular solids. One application is the production of detonators where powders of energetic material and a binder are typically mixed and compacted at high pressure to make pellets. Performance properties are strongly dependent on particle size distribution, surface area of its constituents, homogeneity of the mix, and void volume. The goal is to produce detonators with fast energy release rate the are insensitive to unintended initiation. In this paper, we report results of our early work in this field of research, including the preparation of detonators from xerogel molding powders and aerogels, comparing the material properties with present state-of-the-art technology.

  5. Sol-gel coatings for optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Avellaneda, Cesar O.; Macedo, Marcelo A.; Florentino, Aariovaldo O.; Aegerter, Michel A.

    1994-09-01

    Nb2O5 prepared by a sol-gel process in form of coatings and aerogels are new materials which present interesting properties: (a) the coatings present electrochromic properties and exhibit a blue coloration under Li+ insertion with 100% reversible variation of the optical transmission in the visible and near infrared range between 80% and 20% and have a high chemical stability (tested up to 2000 cycles), (b) they are semiconductor and present a photoelectric effect when illuminating in the UV region ((lambda) < 360 nm). These films are therefore very promising to be used in electrochromic devices, as electrodes for photoelectrochemical purpose and the development of nanocrystalline solar cell, and (c) when prepared in aerogel form, the high BET surface area of the powders is a promising asset to use these new materials for catalytic purposes.

  6. Evaluation of sol-gel methods for the synthesis of doped-ceria environmental catalysis systems. Part I: preparation of coatings

    Microsoft Academic Search

    Christos Agrafiotis; Athena Tsetsekou; C. J Stournaras; Anne Julbe; Laetitia Dalmazio; Christian Guizard

    2002-01-01

    Sol-gel technology can be employed for the synthesis of multi-component nanophase environmental catalysts with enhanced catalytic activity, controlled composition and tailor-made pore structure together with their simultaneous deposition upon porous supports. The conditions for effective deposition of nano-phase doped-ceria systems onto cordierite honeycombs through sol-gel routes were investigated. For the direct casting from the sol phase, the sol rheological characteristics

  7. Lead oxide coatings on sol-gel derived lead lanthanum zirconium titanate thin layers for enhanced crystallization into the perovskite structure

    Microsoft Academic Search

    Toshihiko Tani; David A. Payne

    1994-01-01

    An improved method is described for the sol-gel preparation of PLZT thin layers in the perovskite structure. The method uses a PbO cover coat. Details are reported for the sol-gel processing route and heat-treatment conditions. Through use of this method it is possible to prepare single-phase perovskite material with improved properties. The deleterious effect of additional phases--which are not present

  8. Current issues in sol-gel reaction kinetics

    SciTech Connect

    Assink, R.A.; Kay, B.D.

    1990-01-01

    This paper surveys a few of the current issues in sol-gel reaction kinetics. Many times seemingly modest changes in reactants or reaction conditions can lead to substantial differences in the overall reaction rates and pathways. For example, qualitative features of the reaction kinetics can depend on catalyst concentration. At very high acid-catalyst concentrations, reverse are significant for TMOS sol-gels, while for moderate acid-catalyst concentrations, reverse reactions are substantially reduced. The reaction kinetics are substantially reduced. The reaction kinetics of two similar tetraalkoxysilanes: tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), can be markedly different under identical reaction conditions. Under acid-catalyzed reaction conditions, a TMOS sol-gel undergoes both water-and alcohol-producing condensation reactions while a TEOS sol-gel undergoes only water-producing condensation. The early time hydrolysis and condensation reactions of a TMOS sol-gel are statistical in nature and can be quantitatively described by a few simple reaction rate constants while the reaction behavior of a TEOS sol-gel is markedly nonstatistical. A comprehensive theory of sol-gel kinetics must address diverse experimental findings. 9 refs., 3 figs., 1 tab.

  9. Photoelectrochemical investigations on particulate ZnO thin film electrodes in non-aqueous solvents

    Microsoft Academic Search

    Lal Bahadur; Tata N. Rao

    1995-01-01

    This particulate films of ZnO prepared from its ultrafine colloidal particles obtained by the sol-gel technique were studied as photoelectrodes in non-aqueous photoelectrochemical cells. With the use of non-aqueous (acetonitrile and propylene carbonate) electrolytes, higher photovoltage and photocurrent were observed as compared with those obtained with aqueous electrolyte. In propylene carbonate medium the particulate ZnO thin film electrode exhibited an

  10. Structural and dielectric/ferroelectric properties of (La{sub 1-x}Nd{sub x}){sub 2}Ti{sub 2}O{sub 7} synthesized by sol-gel route

    SciTech Connect

    Shao Zhenmian [Univ Lille Nord de France, F-59000 Lille (France); UArtois, UCCS, F-62300 Lens (France); CNRS, UMR 8181, F-59650 Villeneuve d'Ascq (France); ENSCL, UCCS, F-59652 Villeneuve d'Ascq (France); Saitzek, Sebastien, E-mail: sebastien.saitzek@univ-artois.f [Univ Lille Nord de France, F-59000 Lille (France); UArtois, UCCS, F-62300 Lens (France); CNRS, UMR 8181, F-59650 Villeneuve d'Ascq (France); Roussel, Pascal; Mentre, Olivier [Univ Lille Nord de France, F-59000 Lille (France); CNRS, UMR 8181, F-59650 Villeneuve d'Ascq (France); ENSCL, UCCS, F-59652 Villeneuve d'Ascq (France); Prihor Gheorghiu, Felicia; Mitoseriu, Liliana [University Al. I. Cuza Iasi, Department of Physics, Bv. Carol I, 11, Iasi 700506 (Romania); Desfeux, Rachel [Univ Lille Nord de France, F-59000 Lille (France); UArtois, UCCS, F-62300 Lens (France); CNRS, UMR 8181, F-59650 Villeneuve d'Ascq (France)

    2010-07-15

    A series of compounds with the general formula (La{sub 1-x}Nd{sub x}){sub 2}Ti{sub 2}O{sub 7} (0.0{<=}x{<=}1.0) has been prepared by the sol-gel method. The decomposition of the gel was characterized by thermo-gravimetric analysis coupled to mass spectrometry, indicating the reaction is achieved above 850 {sup o}C. The lattice parameters versus x show an expected decrease in the a and b parameters while c and the {beta} angle remain almost unchanged with respect to the monoclinic symmetry conserved for the full solid solution. Dielectric, piezoelectric and ferroelectric properties were measured on the entire series. - Graphical abstract: XRD patterns of (La{sub 1-x}Nd{sub x}){sub 2}Ti{sub 2}O{sub 7} powders for various x values. The (hkl) peaks positions (with h and k{ne}0) change with x values while the (00l) peaks positions remain unaffected.

  11. Effect of annealing temperature on optical properties of binary zinc tin oxide nano-composite prepared by sol-gel route using simple precursors: Structural and optical studies by DRS, FT-IR, XRD, FESEM investigations

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-01

    Binary zinc tin oxide nano-composite was synthesized by a facile sol-gel method using simple precursors from the solutions consisting of zinc acetate, tin(IV) chloride and ethanol. Effect of annealing temperature on optical and structural properties was investigated using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD results revealed the existence of the ZnO and SnO2 phases. FESEM results showed that binary zinc tin oxide nano-composites ranges from 56 to 60 nm in diameter at 400 °C and 500 °C annealing temperatures respectively. The optical band gap was increased from 2.72 eV to 3.11 eV with the increasing of the annealing temperature. FTIR results confirmed the presence of zinc oxide and tin oxide and the broad absorption peaks at 3426 and 1602 cm-1 can be ascribed to the vibration of absorptive water, and the absorption peaks at 546, 1038 and 1410 cm-1 are due to the vibration of Zn-O or Sn-O groups in binary zinc tin oxide.

  12. Organofunctional Sol-Gel Materials for Toxic Metal Separation

    SciTech Connect

    Im, Hee-Jung; Yost, Terry L.; Yang, Yihui; Bramlett, J. Morris; Yu, Xiang-Hua; Fagan, Bryan C.; Allain, Leonardo R.; Chen, Tianniu; Xue, Ziling; Barnes, Craig E.; Dai, Sheng; Rocker, Lee E.; Sepaniak, Michael J.

    2003-09-10

    Inorganic-organic silica sol-gels grafted or encapsulated with organic ligands were prepared and found to selectively and reversibly remove target metal ions such as Cu2+, Cd2+, and Sr2+. These organofunctional sol-gel materials, which were easily prepared from off-the-shelf chemicals, were hydrophilic and showed fast kinetics of metal uptake. The sol-gels were easily regenerated and used in multi-cycle metal removal. In our search for new ligands for metal removal, we found that the reactions of thioacetal ligands with Hg2+ gave Hg(SCH2COOH)2. Our studies of organofunctional sol-gel materials for metal separation will be discussed.

  13. Production of continuous mullite fiber via sol-gel processing

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Sparks, J. Scott; Esker, David C.

    1990-01-01

    The development of a continuous ceramic fiber which could be used in rocket engine and rocket boosters applications was investigated at the Marshall Space Flight Center. Methods of ceramic fiber production such as melt spinning, chemical vapor deposition, and precursor polymeric fiber decomposition are discussed and compared with sol-gel processing. The production of ceramics via the sol-gel method consists of two steps, hydrolysis and polycondensation, to form the preceramic, followed by consolidation into the glass or ceramic structure. The advantages of the sol-gel method include better homogeneity and purity, lower preparation temperature, and the ability to form unique compositions. The disadvantages are the high cost of raw materials, large shrinkage during drying and firing which can lead to cracks, and long processing times. Preparation procedures for aluminosilicate sol-gel and for continuous mullite fibers are described.

  14. Electrophoretic Porosimetry of Sol-Gels

    NASA Technical Reports Server (NTRS)

    Snow, L. A.; Smith, D. D.; Sibille, L.; Hunt, A. J.; Ng, J.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    It has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.

  15. Sol-gel-derived percolative copper film

    SciTech Connect

    Szu Sungping [Department of Physics, National Chung-Hsing University, Taichung 402, Taiwan (China)], E-mail: spszu@phys.nchu.edu.tw; Cheng, C.-L. [Department of Physics, National Chung-Hsing University, Taichung 402, Taiwan (China)

    2008-10-02

    Cu-SiO{sub 2} films were prepared by the sol-gel method. Two-dimensional fractal copper films were formed after the films were thermally treated in reducing atmosphere. dc resistances of the films decrease 12 orders of magnitude as the content of copper increases from 70 to 80 mol%. During the resistance measurement under argon atmosphere, samples showed a sharp increase or decrease of resistance at a transition temperature which is ascribed to the oxidation of Cu into CuO. The oxidation was also observed in the in situ high temperature X-ray diffraction under vacuum condition. The evolution of the morphology of the films was studied by scanning electron microscopy. As the content of copper increases, the forms of copper particles change from discrete to aggregate then to interconnecting. The coverage coefficients of the copper range from 23 to 55% and the fractal dimensions range from 1.65 to 1.77. The percolation thresholds for the coverage coefficient and the fractal dimension are about 33% and 1.71, respectively, which corresponds to the sample containing 72.5 mol% of Cu.

  16. Net shape ceramic microcomponents by modified sol–gel casting

    Microsoft Academic Search

    C. M. Chan; G. Z. Cao; T. G. Stoebe

    2000-01-01

    Development of ceramic microcomponents can open up the current silicon-based MEMS (micro-electro-mechanical systems) technology\\u000a to new applications, especially for use in high temperature, chemically reactive environments. We report a study of sol–gel\\u000a technologies applied to the fabrication of microcomponents. Organic\\/inorganic hybrid materials, particularly silica-based\\u000a hybrids, were developed by sol–gel processing. A weak silica network was made possible by using acid

  17. Technology and applications of sol-gel materials

    NASA Astrophysics Data System (ADS)

    Maruszewski, K.; Strek, W.; Jasiorski, M.; Ucyk, A.

    2003-01-01

    A brief review of some aspects of technology and applications of the sol-gel technology is presented. The content is divided into three parts concerning: (1) synthetic aspects of this technique, (2) optical sensors (optodes) and (3) pure and doped silica nanopowders manufactured by the sol-gel method. The versatility and applicability of the method is discussed. Also, several examples of active ("smart") materials obtained by this technique are presented.

  18. Chemical sensing of copper phthalocyanine sol-gel glass through organic vapors

    NASA Astrophysics Data System (ADS)

    Ridhi, R.; Gawri, Isha; Abbas, Saeed J.; Saini, G. S. S.; Tripathi, S. K.

    2015-05-01

    The sensitivities of metallophthalocyanine to vapor phase electron donors has gained significance in many areas and disciplines due to their sensing properties and ease of operation. In the present study the interaction mechanism of organic vapors in Copper Phthalocyanine (CuPc) sol-gel glass has been studied. The interaction mechanism is affected by many factors like morphology, electrical or optical properties of film. CuPc sol-gel glass has been synthesized using chemical route sol-gel method. Its structural characterization was conducted using XRD and the amorphous nature of the silicate glass was observed with characteristic ? polymorph phase of CuPc at around 6.64? with 13.30Å interplanar spacing. The size of the particle as determined using Debbye Scherre's formula comes out around 15.5 nm. The presence of ? phase of CuPc was confirmed using FTIR with the appearance of crystal parameter marker band at 787 cm-1. Apart from this A2u and Eu symmetry bands of CuPc have also been observed. The UV absorption spectrum of CuPc exhibits absorption peaks owing to ?? ?* and n? ?* transitions. A blue shift in the prepared CuPc glass has been observed as compared to the dopant CuPc salt indicating increase of band gap. A split in B (Soret) band and Q band appears as observed with the help of Lorentzian fitting. CuPc sol gel glass has been exposed with chemical vapors of Methanol, Benzene and Bromine individually and the electrical measurements have been carried out. These measurements show the variation in conductivity and the interaction mechanism has been analyzed.

  19. Nondestructive evaluation of sol–gels using terahertz time-domain reflectance spectroscopy to probe the effects of dendrimer incorporation and humidity on sol–gel aging

    Microsoft Academic Search

    Anita R. Taulbee-Combs; Matthew J. Bachus; Kamila M. Wiaderek; William H. Steinecker; Zechariah D. Sandlin; James A. Cox; Gilbert E. Pacey

    2010-01-01

    Terahertz (THz) time-domain reflectance spectroscopy is evaluated as a technique for nondestructive analysis of sol–gels over\\u000a the first week of aging without directly contacting or disturbing the sol–gels. In the sol–gels analyzed, tetramethyl orthosilicate\\u000a (TMOS) is the precursor and polyamidoamine (PAMAM) dendrimers are incorporated into each of two sol–gel sample groups; a third\\u000a control group contains no dendrimer. The study

  20. Nanocrystalline spin coated sol-gel hydroxyapatite thin films on Ti substrate: Towards potential applications for implants

    NASA Astrophysics Data System (ADS)

    Carradò, Adele; Viart, Nathalie

    2010-07-01

    Sol-gel spin coating is a promising process to obtain hydroxyapatite (HA) thin films. It is an alternative route to the hydroxyapatite deposition techniques usually employed to cover orthopaedic or dental titanium implant surfaces. The sol-gel (SG) parameters leading to a pure and crystalline HA coatings on Ti substrate were determined. They allow to reach a stoichiometric hydroxyapatite composition (ideal Ca/P atomic ratio 1.67) and a control of the growth of the crystalline phases. The samples, when observed by Scanning Electron Microscopy (SEM), exhibit grains of ca. 200 nm, well adapted for cell proliferation. The crystallisation of the HA films was thoroughly studied by X-Ray diffraction (XRD). The aim of this paper is to validate the sol-gel method as a processing method allowing the control of the mechanical state of the films and, in particular, of the residual stresses (RS) at metal-ceramic interfaces. These stresses were determined on titanium substrates. While the uncoated Ti substrates were in a compressive residual state, the coated ones were in a low tensile state. These results suggest that the sol-gel process is indeed a processing route to obtain HA coated Ti implants.

  1. Structural and spectroelectrochemical investigations of tetragonal CeVO 4 and Ce\\/V-oxide sol-gel derived ion-storage films

    Microsoft Academic Search

    U Opara Krašovec; B Orel; A Šurca; N Bukovec; R Reisfeld

    1999-01-01

    Thin films of CeVO4 prepared via the sol-gel route, with a tetragonal (I41\\/amd) crystalline structure, show good ion-storage properties. The sol-gel route combined with the dip-coating deposition technique allowed thin solid films and powders with a specific Ce\\/V molar ratio (Ce\\/V=2:1, 1:1 (CeVO4), 1:2) to be made. The structure of films and powders prepared at 400°C, and at different times

  2. Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials

    NASA Technical Reports Server (NTRS)

    Fang, Jonathan; Zhou, Jing C.; Lan, Esther H.; Dunn, Bruce; Gillman, Patricia L.; Smith, Scott M.

    2004-01-01

    An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more "rugged" sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection

  3. Solid-state NMR study of geopolymer prepared by sol-gel chemistry

    NASA Astrophysics Data System (ADS)

    Tsai, Yi-Ling; Hanna, John V.; Lee, Yuan-Ling; Smith, Mark E.; Chan, Jerry C. C.

    2010-12-01

    Geopolymers are a new class of materials formed by the condensation of aluminosilicates and silicates obtained from natural minerals or industrial wastes. In this work, the sol-gel method is used to synthesize precursor materials for the preparation of geopolymers. The geopolymer samples prepared by our synthetic route have been characterized by a series of physical techniques, including Fourier-transform infrared, X-ray diffraction, and multinuclear solid-state NMR. The results are very similar to those obtained for the geopolymers prepared from natural kaolinite. We believe that our synthetic approach can offer a good opportunity for the medical applications of geopolymer.

  4. Evaluation of sol–gel methods for the synthesis of doped-ceria environmental catalysis systems

    Microsoft Academic Search

    Christos Agrafiotis; Athena Tsetsekou; C. J. Stournaras; Anne Julbe; Laetitia Dalmazio; Christian Guizard; Gianmarco Boretto; Massimo Debenedetti; Flavio Parussa

    2001-01-01

    Nanophase calcia-doped-ceria-based washcoats with the molar composition (CeO)0.25(CaO)0.02(Al2O3)0.73\\/(Pd, Rh), deposited on ceramic honeycombs via sol–gel methods were evaluated with respect to catalytic activity for hydrocarbons conversion and thermal aging.With the proper synthesis and deposition route, such systems were tailor-made with a meso-porous structure similar to that of commercial catalysts and with significant resistance to pore collapse and surface area loss

  5. Photocatalytic activities of multiferroic bismuth ferrite nanoparticles prepared by glycol-based sol–gel process

    Microsoft Academic Search

    X. WangY; Y. Lin; Z. C. Zhang; J. Y. Bian

    The uniform multiferroic BiFeO3 nanoparticles with fairly narrow particle size distribution have been successfully synthesized by a simple glycol-based sol–gel\\u000a route at relatively low temperature. The thus-prepared powders were characterized by X-ray diffractometry (XRD), thermogravimetric\\u000a and differential thermal analysis (DTA\\/TG), and transmission electron microscopy (TEM). Rapid sintering and subsequently quenching\\u000a to room temperature are the two vital important factors for

  6. The effect of lithiation on the electrochromism of sol-gel derived niobium oxide films

    SciTech Connect

    Macek, M.; Orel, B.; Krasovec, U.O. [National Inst. of Chemistry, Ljubljana (Slovenia)

    1997-09-01

    Niobium oxide films are promising cathodic electrochromic materials that in certain aspects can compete with the more frequently studied WO{sub 3} films. The films reported here were prepared using the sol-gel route from a NbCl{sub 5} precursor. The electrochromic properties were pronounced for crystalline films heat-treated at 500 C exhibiting transmittance changes between the colored and bleached states of 60% in the ultraviolet (UV) and 80% in the visible and near-infrared spectral regions. The reversibility of electrochromic changes of thick niobium oxide films (d > 250 nm) was enhanced by lithiation.

  7. Sol-gel technology for ferroelectric thin films

    SciTech Connect

    Kim, You Song [Research Institute of Industrial Science and Technology, Pohang (Korea, Democratic People`s Republic of); Jang, Hyun M. [Pohang Univ. of Science and Technology (Korea, Democratic People`s Republic of)

    1994-12-31

    Sol-gel-derived ferroelectric thin films can offer particular promise for various microelectronic applications, including FRAM, DRAM elements, thin-film capacitors and pyroelectric IR sensors. In this article, recent progress in the sol-gel processing of two typical ferroelectric thin-film systems is briefly reviewed. These are lead zirconate titanate (PZT) solid solution and Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-based relaxor ferroelectrics. Several examples of the sol chemistry-structures/ferroelectric properties relationships are illustrated using various recent data, including results from the authors` laboratory.

  8. Indium selenide thin film preparation by sol–gel technique

    Microsoft Academic Search

    Ibrahim H. Mutlu; Maharram Z. Zarbaliyev; Ferhat Aslan

    2007-01-01

    s  Preparation and characterization of In–Se compound thin films prepared by sol–gel methods on glass substrate have been studied.\\u000a X-ray diffraction analyses and optical transmission spectrum of In–Se compound thin film samples show that the fabricated\\u000a sol–gel In–Se thin films features formed mainly as an In2Se3 crystal structure. From transmission spectra of In–Se thin films band gap energy were estimated approximately

  9. Ferroelectric thin films fabricated by sol-gel technique

    Microsoft Academic Search

    Yuhuan Xu

    2001-01-01

    This paper reviews our studies of sol-gel processes for some of ferroelectric thin films, including PZT, PLZT, BaTiO3, LiNbO 3, KNbO3, and Sr0.6Ba0.4Nb 2O6, etc. Different microstructures, such as epitaxial (single crystal-like), polycrystalline, and amorphous films, which depend on the sol-gel processing, were studied. Some interested phenomena including thickness effect, interface effect, ferroelectric-like property of amorphous, second harmonic generation, electro-optical

  10. Sol-gel synthesis of phosphate ceramic composites II

    SciTech Connect

    Cao, Z.; Lee, B.I. [Department of Ceramic and Materials Engineering, Clemson University, Clemson, South Carolina 29634-0907 (United States); Samuels, W.D.; Wang, L.; Exarhos, G.J. [Battelle Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)

    1998-06-01

    Phosphate ceramics were synthesized using the sol-gel technique of direct reaction of P{sub 2}O{sub 5} with tetraethoxy silane (TEOS) or titanium tetraethoxide (Ti(OEt){sub 4}). The reaction mechanism of P{sub 2}O{sub 5} and TEOS was deduced using liquid and solid-state NMR. Hexacoordinated silicon in phosphosilicate gels was observed. A specially structured titanium phosphate-layered Ti(HPO{sub 4}){sub 2}{center_dot}2H{sub 2}O was synthesized for the first time through the sol-gel method. The gelation process and sintering properties were investigated. {copyright} {ital 1998 Materials Research Society.}

  11. Application of energy-dispersive X-ray elemental mapping to probe the homogeneity of sol-gel derived YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} and related phases

    SciTech Connect

    Houk, C.S.; Burgoine, G.A.; Page, C.J. [Univ. of Oregon, Eugene, OR (United States)

    1995-04-01

    The authors describe results obtained using energy dispersive X-ray (EDX) elemental mapping to probe the homogeneity of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. Sol-gel synthesis and conventional solid-state synthesis of the ceramic with firing to 950{degrees}C and sol-gel synthesis with firing at 700{degrees}C are the synthetic routes considered. It was found that the low temperature sol-gel method yields high-quality YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} provided the firing stage is of sufficient duration.

  12. Characterization of Hafnia Powder Prepared from an Oxychloride Sol Gel

    SciTech Connect

    McGilvery, Catriona M. [Imperial College, London; De Gendt, S [Imperial College, London; Payzant, E Andrew [ORNL; MacKenzie, M [Imperial College, London; Craven, A J [Imperial College, London; McComb, D W [Imperial College, London

    2011-01-01

    Hafnium containing compounds are of great importance to the semiconductor industry as a replacement for Si(O,N) with a high- gate dielectric. Whilst Hf is already being incorporated into working devices1, much is still to be understood about it. Here we investigate the crystallisation processes and chemistry of bulk HfO2 powders which will aid in interpretation of reactions and crystallisation events occurring in thin films used as gate dielectrics. Amorphous HfO2 powder was prepared via a sol-gel route using hafnium oxychloride (HfOCl2 xH2O) as a precursor. The powders were subjected to various heat treatments and analysed using x-ray diffraction (XRD) and thermal analysis techniques. It was found that a large change in the crystallisation pathway occurred when the sample was heated in an inert environment compared with in air. Instead of the expected monoclinic phase (m-HfO2), tetragonal HfO2 (t-HfO2) also formed under these conditions and was observed up to temperatures of ~760 C. The t-HfO2 particles, which are less than 30nm in size, eventually transform into m-HfO2 on further heating. Possible mechanisms for the crystallisation of t-HfO2 are discussed. It is proposed that within this temperature range t-HfO2 is stabilised due to the presence of oxygen vacancies in the inert environment, forming by the reduction of HfIV to HfIII. As the crystal grows in size as the temperature increases there are too few oxygen vacancies left in the structure to continue stabilising the t-HfO2 phase and so transformation to m-HfO2 occurs.

  13. Hydrophobic self-cleaning surfaces of ZnO thin films synthesized by sol-gel technique Hydrophobic self-cleaning surfaces of ZnO thin films synthesized by sol-gel technique

    Microsoft Academic Search

    S. Patra; S. Sarkar; S. K. Bera; R. Ghosh; G. K. Paul

    2011-01-01

    This paper reported on highly transparent self-cleaning surfaces of zinc oxide synthesized via the sol-gel route. The results, including the x-ray diffraction, optical transmittance spectra, atomic force microscopy and the contact angles, were also reported in the paper, along with a discussion on the hydrophobic properties of zinc oxide. However, upon further investigation of the hydrophobicity of zinc oxide thin

  14. Enhanced photoelectrochemical performance of Ti-doped hematite thin films prepared by the sol–gel method

    Microsoft Academic Search

    Xiaojuan Lian; Xin Yang; Shangjun Liu; Ying Xu; Chunping Jiang; Jinwei Chen; Ruilin Wang

    Ti-doped ?-Fe2O3 thin films were successfully prepared on FTO substrates by the sol–gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed ?-Fe2O3 had a preferred (110) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed

  15. Sol–gel derived Pb(Zr,Ti)O 3 thin films: Residual stress and electrical properties

    Microsoft Academic Search

    R. J. Ong; T. A. Berfield; N. R. Sottos; D. A. Payne

    2005-01-01

    Pb(Zr,Ti)O3 compositions are under investigation for applications that include integrated capacitors, piezoelectric sensors, and actuators. Sol–gel synthesis and spin coating are popular routes to the formation of high quality, dense, crack free, insulating films. However, the electrical properties of the films are often different than those measured for bulk specimens of the same composition. Pb(Zr0.53Ti0.47)O3 films were deposited from a

  16. Effect of different fuels on the alumina–ceria composite powders synthesized by sol–gel auto combustion method

    Microsoft Academic Search

    J. Chandradass; M. Balasubramanian; Dong-sik Bae; Ki Hyeon Kim

    2009-01-01

    In this research, a sol–gel auto combustion route has been proposed to synthesize alumina–ceria composite powder, using aluminium nitrate, cerium(III) nitrate hexahydrate and various fuels such as citric acid, acetyl acetone and oxalic acid. DTA shows the phase transformation of ?-Al2O3 and CeO2 varies with fuel. XRD confirms the formation of ?-Al2O3 and CeO2 phase irrespective of fuels at 1200°C.

  17. Influence of Heat Treatment on Structure and Charge Capacity of Sol-Gel Produced TiO2 Films

    NASA Astrophysics Data System (ADS)

    Özdemir, Orhan; Gökdemir, Fatma P?nar; Keskin, Bahad?r; Kutlu, Kubilay

    Titanium dioxide thin films were synthesized by sol-gel route from titanium isopropoxide (TIP) with acetic acid. Prior to the heat treatment, the films were amorphous phase. Above 400 °C, phase transition took place from amorphous into anatase phase. Electrochromic properties of each phase indicated reversible coloration upon Li+ ion intercalation in cyclic voltammetric measurements. Nevertheless, both charge capacity and energy band gap of films begun to decrease with increase in annealing temperature due to the crystallization.

  18. Synthesis of lanthanum oxide doped photocatalytic nano titanium oxide through aqueous sol–gel method for titania multifunctional ultrafiltration membrane

    Microsoft Academic Search

    K. A. Manjumol; V. S. Smitha; P. Shajesh; K. V. Baiju; K. G. K. Warrier

    2010-01-01

    An all aqueous sol gel route has been demonstrated for the synthesis of titania multifunctional ultrafiltration membrane on\\u000a porous alumina substrate. Doping with lanthana was used to increase the thermal stability of anatase phase. This resulted\\u000a in a nanoporous membrane with considerable percentage of anatase phase even after consolidation at 800°C. The highly homogeneous\\u000a membranes with a thickness of ~4–5 ?m

  19. Microstructural and antibacterial properties of zinc-substituted cobalt ferrite nanopowders synthesized by sol-gel methods

    NASA Astrophysics Data System (ADS)

    Sanpo, Noppakun; Berndt, Christopher C.; Wang, James

    2012-10-01

    Zinc-substituted cobalt ferrite nanopowders were prepared via a sol-gel route using citric acid as a chelating agent. The influence of zinc concentration on the microstructure, crystal structure, surface wettability, surface roughness, and antibacterial property of zinc-substituted cobalt ferrite nanopowders was investigated systematically. The substitution of zinc influences slightly the microstructure, surface wettability, surface roughness, and crystal structure but strongly affects the antibacterial property of the cobalt ferrite nanopowders.

  20. Process of forming a sol-gel/metal hydride composite

    DOEpatents

    Congdon, James W. (Aiken, SC)

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  1. ARSENIC REMOVAL USING SOL-GEL SYNTHESIZED TITANIUM DIOXIDE NANOPARTICLES

    EPA Science Inventory

    In this study, the effectiveness of TiO2 nanoparticles in arsenic adsorption was examined. TiO2 particles (LS) were synthesized via sol-gel techniques and characterized for their crystallinity, surface area and pore volume. Batch adsorption studies were perf...

  2. Dynamics of Proteins Encapsulated in Silica Sol-Gel Glasses Studied with IR Vibrational Echo Spectroscopy

    E-print Network

    Fayer, Michael D.

    Dynamics of Proteins Encapsulated in Silica Sol-Gel Glasses Studied with IR Vibrational Echo by the extent of spectral diffusion, are the same for both proteins encapsulated in sol-gel glasses compared structural dynamics experienced by a biomolecule. I. Introduction Proteins embedded in silica sol-gel glasses

  3. Hydrophilization coating of silylated polyoxazoline using sol-gel Cdric Alexis,a,b

    E-print Network

    Boyer, Edmond

    -free coating for polymer supports using hybrid sol- gel technique with a new polyoxazoline based precursor1 Hydrophilization coating of silylated polyoxazoline using sol-gel process Cédric Alexis through sol-gel process. AFM, SEM, visible reflectance spectroscopy and contact angle experiments allowed

  4. New insights into uranium (VI) sol-gel processing

    SciTech Connect

    King, C.M.; Thompson, M.C.; Buchanan, B.R. (Westinghouse Savannah River Co., Aiken, SC (USA)); King, R.B. (Georgia Univ., Athens, GA (USA). Dept. of Chemistry); Garber, A.R. (South Carolina Univ., Columbia, SC (USA). Dept. of Chemistry)

    1990-01-01

    Nuclear Magnetic Resonance (NMR) investigations on the Oak Ridge National Laboratory process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been extremely useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub 12}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sup 17}O NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, ((UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}){sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results will be presented to illustrate that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an intercalation'' cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2} ((UO{sub 2}){sub 8} O{sub 4} (OH){sub 10}) {center dot} 8H{sub 2}O. This compound is the precursor to sintered UO{sub 2} ceramic fuel. 23 refs., 10 figs.

  5. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    NASA Technical Reports Server (NTRS)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2004-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil similar JSC-1 in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. Characterization of the precursor molecules and efforts to further concentrate and hydrolyze the products to obtain gel materials will be presented for evaluation as ceramic precursors.

  6. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    NASA Technical Reports Server (NTRS)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2003-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SiO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2,7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil simular in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. The elemental composition and structure of the precursor molecules were characterized. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors.

  7. Calcium hydroxyapatite, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2} ceramics prepared by aqueous sol-gel processing

    SciTech Connect

    Bogdanoviciene, Irma [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Beganskiene, Aldona [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Tonsuaadu, Kaia [Laboratory of Inorganic Materials, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Glaser, Jochen [Institut fuer Anorganische Chemie, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 18, D-72076 Tuebingen (Germany); Meyer, H.-Juergen [Institut fuer Anorganische Chemie, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 18, D-72076 Tuebingen (Germany)]. E-mail: juergen.meyer@uni-tuebingen.de; Kareiva, Aivaras [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania)]. E-mail: aivaras.kareiva@chf.vu.lt

    2006-09-14

    Aqueous sol-gel chemistry routes based on ammonium-hydrogen phosphate as the phosphorus precursor and calcium acetate monohydrate as source of calcium ions have been developed to prepare calcium hydroxyapatite samples with different morphological properties. In the sol-gel processes, an aqueous solutions of ethylene diamine tetra-acetic acid (EDTA) or tartaric acid (TA) as complexing agents were added to the reaction mixture. The monophasic Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2} samples were obtained by calcination of precursor gels for 5 h at 1000 deg. C. The phase transformations, composition and micro-structural features in the polycrystalline samples were studied by thermoanalytical methods (TGA/DTA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). It was shown that adjusting the nature of complexing agent in the aqueous sol-gel processing can be used to control the morphology of the ceramic samples.

  8. F-doped ZnO by sol-gel spin-coating as a transparent conducting thin film

    NASA Astrophysics Data System (ADS)

    Nam, Gil Mo; Kwon, Myoung Seok

    2011-06-01

    This paper reports a simple non-alkoxide sol-gel route for depositing F-doped ZnO thin film on glass substrates. Ammonium fluoride and zinc acetate were used as the dopant precursor and starting material for ZnO, respectively. After the first crystallization at 550°C in air, the sol-gel spin coated ZnO:F thin films at a F concentration < 5 at. % showed a nanosized polycrystalline structure with a c-plane preferred orientation. The structures, electrical resistivity, carrier concentration, mobility and optical transmittance were strongly dependent on the F concentration. The F concentration > 5 at. % degraded the microstructures, electrical conductivity, and optical transmittance. The second post-heat-treatment at 450°C in a reducing environment resulted in higher electrical resistivity than the first post-heat-treatment in air.

  9. Structural investigations of sol-gel-derived LiYF{sub 4} and LiGdF{sub 4} powders

    SciTech Connect

    Lepoutre, S. [Laboratoire des Materiaux Inorganiques, CNRS UMR 6002, Universite Blaise Pascal et Ecole Nationale Superieure de Chimie de Clermont-Ferrand, 24 Avenue des Landais, 63177 Aubiere cedex (France); Boyer, D. [Laboratoire des Materiaux Inorganiques, CNRS UMR 6002, Universite Blaise Pascal et Ecole Nationale Superieure de Chimie de Clermont-Ferrand, 24 Avenue des Landais, 63177 Aubiere cedex (France)], E-mail: damien.boyer@univ-bpclermont.fr; Potdevin, A.; Dubois, M. [Laboratoire des Materiaux Inorganiques, CNRS UMR 6002, Universite Blaise Pascal et Ecole Nationale Superieure de Chimie de Clermont-Ferrand, 24 Avenue des Landais, 63177 Aubiere cedex (France); Briois, V. [Synchrotron SOLEIL, L'Orme des Merisiers, BP48, 91192 Gif-sur-Yvette Cedex (France); Mahiou, R. [Laboratoire des Materiaux Inorganiques, CNRS UMR 6002, Universite Blaise Pascal et Ecole Nationale Superieure de Chimie de Clermont-Ferrand, 24 Avenue des Landais, 63177 Aubiere cedex (France)

    2007-11-15

    A soft synthesis route based on the sol-gel process was used for preparing rare-earth tetrafluoride powders from alkoxide precursors. In-situ fluorination was performed by decomposition of a fluorine containing organic compound named 1,1,1-trifluoro-5-methyl-2,4-hexanedione when sintering the as-prepared xerogel to produce crystallized samples. Both to insure complete departure of organic residues as well as to avoid any oxidation into oxyfluoride, annealing treatment was carried out under fluorine atmosphere. Free-oxygen content of resulting samples was evidenced by infrared and Raman spectroscopies. X-ray absorption spectroscopies (XAS) and {sup 19}F nuclear magnetic resonance (NMR) studies showed that samples heat treated at 300 deg. C are already crystallized but for a full crystallization in LiGdF{sub 4} and LiYF{sub 4} a thermal treatment at 550 deg. C is needed. Temperature dependence of powder morphology was analyzed by scanning electron microscopy (SEM). - Graphical abstract: The sol-gel route is a soft process, which allows developing versatile-shaped compounds. A fluorine organic compound named 1,1,1-trifluoro-5-methyl-2,4-hexadione was used to synthesis LiGdF{sub 4} and LiYF{sub 4} powders based on the sol-gel method. These materials can be used as host lattices for rare-earth ions to provide phosphors.

  10. Morphology evolution of ZrB{sub 2} nanoparticles synthesized by sol-gel method

    SciTech Connect

    Zhang Yun [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li Ruixing, E-mail: ruixingli@yahoo.com [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Jiang Yanshan; Zhao Bin; Duan Huiping [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li Junping; Feng Zhihai [Aerospace Research Institute of Materials and Processing Technology, Beijing 100076 (China)

    2011-08-15

    Zirconium diboride (ZrB{sub 2}) nanoparticles were synthesized by sol-gel method using zirconium n-propoxide (Zr(OPr){sub 4}), boric acid (H{sub 3}BO{sub 3}), sucrose (C{sub 12}H{sub 22}O{sub 11}), and acetic acid (AcOH). Clearly, it was a non-aqueous solution system at the very beginning of the reactions. Here, AcOH was used as both chemical modifier and solvent to control Zr(OPr){sub 4} hydrolysis. Actually, AcOH could dominate the hydrolysis by self-produced water of the chemical propulsion, rather than the help of outer water. C{sub 12}H{sub 22}O{sub 11} was selected, since it can be completely decomposed to carbon. Thus, carbon might be accounted precisely for the carbothermal reduction reaction. Furthermore, we investigated the influence of the gelation temperature on the morphology of ZrB{sub 2} particles. Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 deg. C to a particle chain at 75 deg. C, and then form rod-like particles at 85 deg. C. An in-depth HRTEM observation revealed that the nanoparticles of ZrB{sub 2} were gradually fused together to evolve into a particle chain, finally into a rod-like shape. These crystalline nature of ZrB{sub 2} related to the gelation temperature obeyed the 'oriented attachment mechanism' of crystallography. - Graphical Abstract: Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 deg. C to a particle chain at 75 deg. C, and then form rod-like particles at 85 deg. C. Highlights: > ZrB{sub 2} nanoparticles were synthesized by sol-gel method in an non-aqueous solution system. > AcOH was used as both chemical modifier and solvent to control Zr(OPr){sub 4} hydrolysis. > C{sub 12}H{sub 22}O{sub 11} was selected since it can be completely decomposed to carbon. > Increasing the gelation temperature, the particles changed from sphere-like to rod-like ones. > Crystalline nature of ZrB{sub 2} obeyed the 'oriented attachment mechanism' of crystallography.

  11. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  12. Optical detection of parasitic protozoa in sol-gel matrices

    NASA Astrophysics Data System (ADS)

    Livage, Jacques; Barreau, J. Y.; Da Costa, J. M.; Desportes, I.

    1994-10-01

    Whole cell parasitic protozoa have been entrapped within sol-gel porous silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silica sol before gelation occurs. They remain trapped within the growing oxide network and their cellular organization appears to be well preserved. Moreover protozoa retain their antigenic properties in the porous gel. They are still able to detect parasite specific antibodies in serum samples from infected patients via an enzyme linked immunosorbent assay (ELISA). Antigen- antibody associations occurring in the gel are optically detected via the reactions of a peroxidase conjugate with ortho-phenylenediamine leading to the formation of a yellow coloration. A clear-cut difference in optical density is measured between positive and negative sera. Such an entrapment of antigenic species into porous sol-gel matrices avoids the main problems due to non specific binding and could be advantageously used in diagnostic kits.

  13. Superhydrophobic sol-gel nanocomposite coatings with enhanced hardness

    NASA Astrophysics Data System (ADS)

    Lakshmi, R. V.; Bharathidasan, T.; Basu, Bharathibai J.

    2011-10-01

    Sol-gel superhydrophobic coatings with improved hardness were prepared by embedding fumed silica nanoparticles in a partially condensed hybrid sol of methyltriethoxysilane (MTEOS) and colloidal silica. Fumed silica particles of size 25-30 nm were incorporated in the sol and the mixture was spray-coated on glass substrate. Water contact angle (WCA) of the composite coating increased with increase in silica content of the sol mixture. The concentration of silica in the sol mixture was optimized to obtain robust superhydrophobic coatings with a WCA of 162.5° and a pencil hardness of 5H. The wetting state of water droplet on the sol-gel composite coatings was analysed with both Wenzel and Cassie-Baxter models.

  14. A Sol-Gel Approach to the Insulation of Rutherford Cables

    NASA Astrophysics Data System (ADS)

    Buta, F.; Hascicek, Y. S.; Sumption, M. D.; Arda, L.; Aslanoglu, Z.; Akin, Y.; Collings, E. W.

    2004-06-01

    Two wind-and-react compatible variants for the electrical insulation of Rutherford cables by a sol-gel route have been investigated. The first variant involves the direct application of a sol-gel coating of SnO2-ZrO2 to the surface of the strands in the cable, whereas the second is an indirect approach consisting of coating stainless steel tapes with MgO-ZrO2 that are to be wrapped around or co-wound with the cable. Following the application of the insulation by one of the two methods, the insulation electrical resistance and breakdown voltage were determined for samples consisting of two 7 inches long cables pressed together and vacuum impregnated with epoxy (CTD-101K). With a notable exception, the breakdown voltages on directly insulated cables were too low for practical purposes. Better results, with breakdown voltages ranging from 20 to almost 200 V, were obtained for insulator coatings applied to stainless steel tapes. An additional sintering at 700-800°C for 6-12h of the coatings deposited on stainless steel was found to increase the breakdown voltage.

  15. Preparation of potassium tantalate niobate through sol–gel processing

    Microsoft Academic Search

    C. J LU; A. X KUANG

    1997-01-01

    Potassium tantalate niobate (KTN) KTa0.65Nb0.35O3 powders and thin films of perovskite structure were prepared through sol–gel processing. A homogeneous and stable precursor\\u000a solution was obtained from tantalum ethoxide, niobium ethoxide, and potassium ethoxide in absolute ethanol with a key additive\\u000a of acetic acid. Powder gels were obtained by exposing the solution to atmospheric water, thus hydrolysing the solution. The\\u000a precursor

  16. Biological behavior of sol-gel coated dental implants

    Microsoft Academic Search

    P. A. Ramires; A. Wennerberg; C. B. Johansson; F. Cosentino; S. Tundo; E. Milella

    2003-01-01

    The biocompatibility of dental implants coated with titania\\/hydroxyapatite (HA) and titania\\/bioactive glass (BG) composites obtained via sol-gel process was investigated using an in vitro and in vivo model. A device for the in vitro testing of screw-shaped dental implants was developed, in order to well compare the two experimental models studying the behavior of human MG63 osteoblast-like cells seeded onto

  17. Sol-Gel Thin Films for Plasmonic Gas Sensors.

    PubMed

    Gaspera, Enrico Della; Martucci, Alessandro

    2015-01-01

    Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. PMID:26184216

  18. Synthesis of cadmium tungstate films via sol–gel processing

    Microsoft Academic Search

    Kirk Lennstrom; Steven J. Limmer; Guozhong Cao

    2003-01-01

    Cadmium tungstate is a scintillator material with excellent intrinsic photoluminescent properties. It is highly resistant to gamma radiation, has an almost non-existent afterglow and is highly efficient. Cadmium tungstate is also non-hydroscopic, unlike the more prevalent thallium-doped alkali halide scintillators. In order to create thin films of cadmium tungstate with precise stoichiometric control, a sol–gel processing technique has been applied

  19. Sol–gel synthesis of highly luminescent magnesium oxide nanocrystallites

    Microsoft Academic Search

    Ashok Kumar; Subhash Thota; Shikha Varma; Jitendra Kumar

    2011-01-01

    An attempt has been made to prepare MgO nano-crystallites through decomposition of sol–gel derived magnesium oxalate dihydrate in air, oxygen and nitrogen ambient at 500, 600, 800, and 1000°C for 2h each and study them with regard to their phase, average crystallite size, morphology, and photoluminescence (PL) behaviour. They are shown to possess f.c.c. (NaCl-type) structure with lattice parameter a?4.211Å,

  20. Superhydrophobic sol–gel nanocomposite coatings with enhanced hardness

    Microsoft Academic Search

    R. V. Lakshmi; T. Bharathidasan; Bharathibai J. Basu

    2011-01-01

    Sol–gel superhydrophobic coatings with improved hardness were prepared by embedding fumed silica nanoparticles in a partially condensed hybrid sol of methyltriethoxysilane (MTEOS) and colloidal silica. Fumed silica particles of size 25–30nm were incorporated in the sol and the mixture was spray-coated on glass substrate. Water contact angle (WCA) of the composite coating increased with increase in silica content of the

  1. Electrochemical properties of sol-gel deposited vanadium pentoxide films

    Microsoft Academic Search

    Nilgün Özer

    1997-01-01

    Microstructure, electrochemical and optical properties of sol-gel deposited vanadium pentoxide (V2O5) coatings were investigated. The films were deposited by spin coating on SnO2:F\\/glass and quartz substrates from a polymeric solution of V2O5 derived from vanadium tri(isopropoxide)oxide. Process parameters were investigated for the deposition of V2O5 films exhititing high lithium insertion capability. Investigations were conducted by cyclic voltammetry, impedance analysis, optical

  2. Erbium luminescence in sol–gel derived oxide glass films

    Microsoft Academic Search

    N. V Gaponenko; A. V Mudryi; O. V Sergeev; V. E Borisenko; E. A Stepanova; A. S Baran; A. I Rat’ko; J. C Pivin; J. F McGilp

    1998-01-01

    Sol–gel derived Al2O3, SiO2, TiO2 and In2O3 films, containing about 10 wt.% Er2O3 have been fabricated and the erbium PL (photoluminescence) in the region of 1.53 ?m has been investigated. In contrast to erbium implanted films, a strong influence of host matrix local environment on the electronic structure of Er ions was observed in the Er PL. The dependence of

  3. Synthesis of silica glass using solventless sol-gel process

    Microsoft Academic Search

    Kun-Hong Lee; Yung-Pyo Koh; Jae-Gon Lim

    1994-01-01

    Silica glass was synthesized form TEOS and deionized water using sol-gel process. To introduce the physicochemical effects of ultrasonic waves, an ultrasonic homogenizer was used to mix reactants instead of adding cosolvents. 2-step method was chosen to separate hydrolysis reaction and condensation reaction, and thus to control the microstructure of wet gels. Wet gels were dried in 5–8 hours without

  4. Vibrational spectra of phenyltriethoxysilane, phenyltrimethoxysilane and their sol-gels.

    PubMed

    Li, Ying-Sing; Wang, Yu; Ceesay, Sorrie

    2009-01-01

    Raman and infrared spectra of phenyltriethoxysilane and phenyltrimethoxysilane have been recorded. These silane coupling agents (SCAs) have been used as precursors to prepare sol-gels using acid or base as catalyst under different solution conditions. From the vibrational spectroscopic identification, it was found that the major sol-gel products obtained from different catalysts and different solvents were essentially the same. Vibrational assignments for the SCAs, sol-gel and xerogel have been made based on the group frequencies, the spectral variation collected at different physical and chemical states and the previous spectroscopic studies of similar molecules. The compositions of xerogels after thermal treatments at different temperatures have been analyzed and identified by using infrared spectroscopic method along with thermal gravimetric analysis. Results from the experimental treatments for the xerogels indicated that the xerogel baking at 118 degrees C served to evaporate the sample moisture, the curing at 225 degrees C helped to complete the condensation reaction, and the treatment at 600 degrees C caused the decomposition of the organic group but the siloxane net-work remained essentially unchanged. PMID:18722154

  5. Synthesis of Nano-sized Yttria via a Sol-Gel Process Based on Hydrated Yttrium Nitrate and Ethylene Glycol and Its Catalytic Performance for Thermal Decomposition of NH 4ClO 4

    Microsoft Academic Search

    Weifan Chen; Fengsheng Li; Leili Liu; Yongxiu Li

    2006-01-01

    Nano-sized yttria particles were synthesized via a non-aqueous sol-gel process based on hydrated yttrium nitrate and ethylene glycol. The effects of the molar ratio of ethylene glycol to yttrium ion and calcination temperature on crystallite size of the products were studied. The catalytic performance of the as-prepared yttria for the ammonium perchlorate (AP) decomposition was investigated by differential scanning calorimetry

  6. Direct synthesis of La 9.33Si 6O 26 ultrafine powder via sol–gel self-combustion method

    Microsoft Academic Search

    Changan Tian; Junliang Liu; Jun Cai; Yanwei Zeng

    2008-01-01

    Single phase La9.33Si6O26 ultrafine powder, as a kind of highly activated precursor to prepare medium-to-low temperature electrolyte for solid oxide fuel cells (SOFCs), has been successfully synthesized via a non-aqueous sol–gel and self-combustion approach from the starting materials: lanthanum nitrate (La(NO3)3·6H2O), citric acid, ethylene glycol (EG), tetraethyl orthosilicate (TEOS) and ammonium nitrate. The details of gel's self-combustion were investigated by

  7. Sol-gel powders and supported sol-gel polymers for immobilization of lipase in ester synthesis

    Microsoft Academic Search

    Jyh-Ping Chen; Wei-Shin Lin

    2003-01-01

    Candida rugosa lipase was entrapped in hybrid organic–inorganic sol-gel powder prepared by acid-catalyzed polymerization of tetramethoxysilane (TMOS) and alkyltrimethoxysilanes, and used in catalyzing esterification reactions between ethanol and butyric acid in hexane. Optimum preparation conditions were studied, which are gels made from propyltrimethoxysilane (PTMS)\\/TMOS molar ratio=4:1, hydrolysis time of silane precursor=30min, water\\/silane molar ratio=24, enzyme loading=6.25% (w\\/w) of gel, and

  8. Synthesis of phthalocyanine doped sol-gel materials

    NASA Technical Reports Server (NTRS)

    Dunn, Bruce

    1993-01-01

    The synthesis of sol-gel silica materials doped with three different types of metallophthalocyanines has been studied. Homogeneous materials of good optical quality were prepared and the first optical limiting measurements of dyes in sol-gel hosts were carried out. The properties of these solid state limiters are similar to limiters based on phthalocyanine (Pc) in solution. Sol-gel silica materials containing copper, tin and germanium phthalocyanines were investigated. The initial step in all cases was to prepare silica sols by the sonogel method using tetramethoxy silane (TMOS), HCl and distilled water. Thereafter, the synthesis depended upon the specific Pc and its solubility characteristics. Copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPc4S) is soluble in water and various doping levels (1 x 10 (exp -4) M to 1 x 10 (exp -5) M) were added to the sol. The group IV Pc's, SnPc(OSi(n-hexyl)3)2 and GePc(OSi(n-hexyl)3)2, are insoluble in water and the process was changed accordingly. In these cases, the compounds were dissolved in THF and then added to the sol. The Pc concentration in the sol was 2 x 10(exp -5)M. The samples were then aged and dried in the standard method of making xerogel monoliths. Comparative nanosecond optical limiting experiments were performed on silica xerogels that were doped with the different metallophthalocyanines. The ratio of the net excited state absorption cross section (sigma(sub e)) to the ground state cross section (sigma(sub g)) is an important figure of merit that is used to characterize these materials. By this standard the SnPc sample exhibits the best limiting for the Pc doped sol-gel materials. Its cross section ratio of 19 compares favorably with the value of 22 that was measured in toluene. The GePc materials appear to not be as useful as those containing SnPc. The GePc doped solids exhibit a higher onset energy (2.5 mj and lower cross section ratio, 7. The CuPc4S sol-gel material has a still lower cross section ratio, 4, however, the tetrasulfonate groups make the dye soluble in water which greatly facilitates its incorporation into the sol-gel matrix. The nonlinear transmission of CuPc4S in a pH 2 buffer solution and in a silica xerogel were compared. It is evident that the CuPc4S preserves its optical limiting behavior in the sol-gel matrix, indicating that the fundamental excited state absorption process is essentially the same for a molecule in solution or in the solid state. Although the spectroscopic details of energy level lifetimes are unknown, the significance is that passive optical limiting has been achieved in the solid state via incorporation of a dye into an inorganic host. The only compromise occurs at the extremely high energy regime where photobleaching is observed. This is a result of the limited mobility of the dye molecules in the solid silica host relative to a liquid host. The effects of photodegradation in the xerogel are additive, whereas the solution provides a supply of fresh molecules that are free to enter the active volume between pulses.

  9. Comparing nanostructured hydroxyapatite coating on AZ91 alloy samples via sol-gel and electrophoretic deposition for biomedical applications.

    PubMed

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2014-12-01

    Magnesium is one of the most critical elements in hard tissues regeneration and therefore causes speeding up the restoration of harmed bones, while high deterioration rate of magnesium in body fluid restricts it to be used as biodegradable implants. Alloying magnesium with some relatively nobler metals such as aluminium, zinc, rare earth elements, magnesium-bioceramics composites, and surface modification techniques are some of the routes to control magnesium corrosion rate. In this study AZ91 magnesium alloy had been coated by nanostructured hydroxyapatite via sol-gel dip coating and electrophoretical methods to survey the final barricade properties of the obtained coatings. In order to perform electrophoretic coating, powders were prepared by sol-gel method, and then the powders deposited on substrates utilizing direct current electricity. Zeta potentials of the electrophoresis suspensions were measured to determine a best mode for good quality coatings. Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were used to confirm nanoscale dimension, and the uniformity of the nanostructured hydroxyapatite coating, respectively. Fourier Transform-Infrared and X-ray diffraction analysis were utilized for functional group and phase structure evaluation of the prepared coatings, correspondingly. Electrochemical corrosion tests were performed in SBF at 37±1 (°)C which revealed considerable increase in corrosion protection resistivity and corrosion current density for electrophoretic coated specimens versus sol-gel coated specimens. Results showed that both sol-gel and electrophoretical techniques seem to be suitable to coat magnesium alloys for biomedical applications but electrophoretic coating technique is a better choice due to the more homogeneity and more crystalline structure of the coating. PMID:25095258

  10. Morphology evolution of ZrB 2 nanoparticles synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    Zhang, Yun; Li, Ruixing; Jiang, Yanshan; Zhao, Bin; Duan, Huiping; Li, Junping; Feng, Zhihai

    2011-08-01

    Zirconium diboride (ZrB 2) nanoparticles were synthesized by sol -gel method using zirconium n-propoxide (Zr(OPr) 4), boric acid (H 3BO 3), sucrose (C 12H 22O 11), and acetic acid (AcOH). Clearly, it was a non-aqueous solution system at the very beginning of the reactions. Here, AcOH was used as both chemical modifier and solvent to control Zr(OPr) 4 hydrolysis. Actually, AcOH could dominate the hydrolysis by self-produced water of the chemical propulsion, rather than the help of outer water. C 12H 22O 11 was selected, since it can be completely decomposed to carbon. Thus, carbon might be accounted precisely for the carbothermal reduction reaction. Furthermore, we investigated the influence of the gelation temperature on the morphology of ZrB 2 particles. Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 °C to a particle chain at 75 °C, and then form rod-like particles at 85 °C. An in-depth HRTEM observation revealed that the nanoparticles of ZrB 2 were gradually fused together to evolve into a particle chain, finally into a rod-like shape. These crystalline nature of ZrB 2 related to the gelation temperature obeyed the "oriented attachment mechanism" of crystallography.

  11. Effect of microstructure and surface roughness on the wettability of superhydrophobic sol–gel nanocomposite coatings

    Microsoft Academic Search

    Bharathibai J. BasuV; V. Hariprakash; S. T. Aruna; R. V. Lakshmi; J. Manasa; B. S. Shruthi

    2010-01-01

    Sol–gel nanocomposite coatings were fabricated by spraying precursor mixtures containing hydrophobically modified silica (HMS)\\u000a nanoparticles dispersed in sol–gel matrices prepared with acid-catalyzed tetraethoxysilane (TEOS), and methyltriethoxysilane\\u000a (MTEOS). The hydrophobicity of the coatings increased with increase in the concentration of HMS nanoparticles. Superhydrophobic\\u000a coatings with water contact angle (WCA) of 166° and roll-off angle <2° were obtained by optimizing the sol–gel

  12. Smart Glasses: Molecular Programming of Dynamic Responses in Organosilica Sol-Gels

    Microsoft Academic Search

    Mukti S. Rao; Joel Gray; Bakul C. Dave

    2003-01-01

    The stimuli-responsive behavior of a new class of sol-gel—derived materials prepared from organically-modified alkoxysilane precursors is reported. Starting from judiciously selected molecular precursors, the sol-gel reaction yields a solid state glass—a mechanically robust yet elastic material—that is capable of generating dynamic responses when subjected to different physicochemical stimuli. These materials represent an initial example of stimuli-responsive silica-based sol-gels that exhibit

  13. An Electrochemical Sol–Gel Sensor for Determining Iron by Stripping Voltammetry

    Microsoft Academic Search

    N. Yu. Stozhko; E. I. Morosanova; L. I. Kolyadina; Zh. M. Azarova

    2004-01-01

    Electrochemical sensors were developed based on thick-film carbon-containing electrodes coated with thin xerogel films fabricated by the sol–gel technology. The effect of the composition of a hydrolyzed mixture and the types of carbon-containing inks and a support on the properties of sol–gel electrodes was studied. Conditions for preparing sol–gel film sensors modified with 1,10-phenanthroline, 2,2'-dipyridyl, Chrome Azurol S, and Eriochrome

  14. Thick ceramic coatings using a sol gel based ceramic-ceramic 0–3 composite

    Microsoft Academic Search

    D. A. Barrow; T. E. Petroff; M. Sayer

    1995-01-01

    A sol gel based coating technology has been developed for making high quality, thick ceramic coatings. The films are ceramic-ceramic 0–3 composites made by dispersing ceramic powders in a sol gel solution. The resulting system has all the benefits of sol gel, i.e. ease of fabrication, ability to coat complex geometries and relative cost effectiveness, but is not limited in

  15. Corrosion inhibition of magnesium by combined zirconia silica sol–gel films

    Microsoft Academic Search

    Yair Tamar; Daniel Mandler

    2008-01-01

    The inhibition of Mg (AZ91D) corrosion by thin sol–gel films was studied. The sol–gel films were prepared by the traditional acid or base-catalyzed hydrolysis and condensation, and finally deposited by dip coating. Two different sol–gel monomers were used: phenyltrimethoxysilane (PTMOS) and zirconium(IV)tetra-1-propoxide (ZrTPO). Films were made of each of the individual monomers and by depositing first a PTMOS film followed

  16. Sol-gel derived porous bioactive nanocomposites: Synthesis and in vitro bioactivity

    NASA Astrophysics Data System (ADS)

    Shankhwar, Nisha; Kothiyal, G. P.; Srinivasan, A.

    2013-06-01

    Porous bioactive composites consisting of SiO2-CaO-Na2O-P2O5 bioactive glass-ceramic and synthetic water soluble polymer Polyvinylpyrrolidone [PVP (C6H9NO)n, MW˜40000 g/mol] have been synthesized by sol-gel route. As-prepared polymeric composites were characterized by X-ray diffraction (XRD) technique. Two major bone mineral phases, viz., hydroxyapatite [Ca10(PO4)6(OH)2] and wollastonite [calcium silicate (CaSiO3)] have been identified in the XRD patterns of the composites. Presence of these bone minerals indicates the bioactive nature of the composites. In vitro bioactivity tests confirm bioactivity in the porous composites. The flexibility offered by these bioactive polymer composites is advantageous for its application as implant material.

  17. Characterization of a sol-gel-entrapped artificial receptor

    NASA Astrophysics Data System (ADS)

    Dunbar, Richard A.; Narang, Upvan; Prasad, Paras N.; Bright, Frank V.

    1993-04-01

    We report on the development, characterization, and photophysics of a new fiber-optic-based sensor which uses a sol-gel entrapped recognition element. The recognition element is modified (beta) -cyclodextrin to which we have added a short tether (glycine) and a fluorophore (dansyl). This recognition element forms an intramolecular complex, and the dansyl group can include within the cyclodextrin cavity. Non-fluorescent analytes, that bind to the cyclodextrin cavity, can effectively displace the included dansyl group and result in a measurable change in signal. We report on the detection limits, dynamic range, and photophysics (i.e., transduction mechanism) of this new sensor.

  18. Characteristics of sol–gel dip coated Ceria films

    Microsoft Academic Search

    K. R. Murali

    2008-01-01

    Cerium oxide(CeO2) thin films were deposited by the sol–gel dip coating technique using cerium chloride, acrylamide and N,N bis methylene acrylamide. The as deposited films were heat-treated at different temperatures in air. X-ray diffraction studies\\u000a indicated the films to be of single phase CeO2. Optical bandgap in the range of 3.53–3.60 eV was obtained from optical studies. Laser Raman studies exhibited

  19. Guided wave measurements for characterization of sol-gel layers

    NASA Astrophysics Data System (ADS)

    Piombini, Hervé; Dieudonne, Xavier; Wood, Thomas; Flory, François

    2013-09-01

    Sol-gel applications require very thick layers with a good understanding of the interfaces. To address this problem, we have installed at CEA Le Ripault a characterization bench using guided waves with assistance from the IM2NP lab in Marseille. This bench allows us to measure the thickness and the refractive index and determine the extinction coefficient of a thin layer. We can distinguish losses at interfaces from those in the bulk according to the chosen propagation mode. This allows us to know if we can stack elementary layers to make thick layers without incurring problems.

  20. Durable hydrophobic sol-gel finishing for textiles

    NASA Astrophysics Data System (ADS)

    Vihodceva, S.; Kukle, S.; Bitenieks, J.

    2015-03-01

    The surface of cotton textile was modified to create a water-repellent finishing by depositing a modifying coatings using the sol-gel technique. Treated textiles evaluated using scanning electron microscopy, X-Ray powder diffraction (XRD). The wettability of treated fabrics was characterized by water contact angle and drop test. The results showed that the cotton textile treated with 7.5 wt.% zinc acetate dihydrate sol showed excellent hydrophobic properties, water contact angle could reach 145°C without decreasing after 50 hydrothermal treatment cycles.

  1. Wrinkling of a sol-gel-derived thin film.

    PubMed

    Kwon, S Joon; Park, Jae-Hwan; Park, Jae-Gwan

    2005-01-01

    We report on the wrinkle formation in a thin film produced by the sol-gel method. Through the relaxation of stress, which results from the removal of the solvent during the drying process, an isotropic wavy pattern is generated in the form of skeletal branches. The patterns have a dominant wavelength satisfying a relationship of three-fourths order of thickness. Densification of the gelated film is enhanced by an increase in the volumetric strain caused by the evaporation of the remaining solvent from the film. The number of skeletal branches and surface roughness increases as the annealing time progresses, without any change in the skeletal wavelength. PMID:15697615

  2. Sol-gel coatings for chemical protection of stainless steel

    Microsoft Academic Search

    PEDRO DE LIMA NETO; Mohamed Atik; Luis A. Avaca; Michel A. Aegerter

    1994-01-01

    Sol-gel thin coatings of ZrO2, SiO2, 70SiO2-30TiO2 and 88SiO2-12Al2O3 compositions (mole %) have been prepared from sonocatalyzed sols and deposited by dip-coating technique on 316L stainless steel foils. The influence of the coatings on the chemical corrosion of the substrate has been measured through potentiodynamic polarization curves in aqueous 15% H2SO4 solution between 25 and 50°C. The values of the

  3. Epitaxial Growth of Yb2O3 Buffer Layers on Biaxially Textured-Ni (100) Substrates by Sol-Gel Process

    SciTech Connect

    Beach, D.B.; Chirayil, T.G.; Christen, D.K.; Feenstra, R.; Goyal, A.; Kroeger, D.M.; Lee, D.F.; Martin, P.M.; Morrell, J.S.; Paranthaman, M.; Sun, E.Y.; Verebelyi, D.T.; Williams, R.K.

    1999-04-05

    In order to develop an alternative buffer layer architecture using the sol-gel process to produce YBCO (YBa2Cu307+) coated conductors, Yb203 has been chosen as the candidate material. Buffer layers of fi03 were epitaxkdly grown on biaxially textured-Ni (100) substrates by the sol gel process for the first time. The ~03 precursor solution was prepared from an alkoxide sol-gel route in 2-xnetho~ethanol and was deposited on textured-Ni (100) substrates by either spin coating or dip coating methods. The amorphous film was then processed at 1160oC under flowing (96%)MH2(4%) gas mixture for one hour. The fi03 iihn exhibited a strong c-axis orientation on the Ni (100) substrates. The phi and omega scans indicated good in plane and out of plane orientations. The X-ray (222) pde figure showed a cube-on-cube epitaxy. High current YBCO films were grown on the Y&03 sol-gel buffered-Ni substrates.

  4. Optical materials by a modified sol-gel nanoparticle process

    NASA Astrophysics Data System (ADS)

    Schmidt, Helmut K.; Mennig, Martin

    2000-05-01

    Optical sol-gel materials have been of interest for many years. The reason is that through the preparation of sold with nanoparticulate liquid structures, transparent coatings of many inorganic oxides can be produced. By using oxides for example, with different refractive indices, reflective or antireflective coatings can be fabricated. To obtain stable layers, the gel coating have to be densified at higher temperatures, in general between 400 and 600 degrees C. This may be suitable for glass surfaces, but not for temperature sensitive substrates like plastics. In addition to this, if multilayer coatings have to be produced, between each step a densification process has to be carried out before the net coating step takes place. This leads to an unsatisfying situation if industrial low cost processing is required. In addition to this, the dip coating process is not suitable for high speed or large area coating techniques. This is one of the reasons whey the sol-gel process never has gained a real high significance for industrial coatings on glass and is limited to special products so far.

  5. Titanium (IV) sol-gel chemistry in varied gravity environments

    NASA Astrophysics Data System (ADS)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    Sol-gel synthesis in reduced gravity is a relatively new topic in the literature and further inves-tigation is essential to realise its potential and application to other sol-gel systems. The sol-gel technique has been successfully applied to the synthesis of silica systems of varying porosity for many diverse applications [1-5]. It is proposed that current methods for the synthesis of silica sol-gels in reduced gravity may be applied to titanium sol-gel processing in order to enhance desirable physical and chemical characteristics of the final materials. The physical and chemical formation mechanisms for titanium alkoxide based sol-gels, to date, is not fully understood. However, various authors [6-9] have described potential methods to control the hydrolysis and condensation reactions of titanium alkoxides through the use of chemical inhibitors. A preliminary study of the reaction kinetics of titanium alkoxide sol-gel reaction in normal gravity was undertaken in order to determine reactant mixtures suitable for further testing under varied gravity conditions of limited duration. Through the use of 1H Nuclear Magnetic Resonance spectroscopy (NMR) for structural analysis of precursor materials, Ultra-Violet-Visible spectroscopy (UV-VIS) and viscosity measurements, it was demonstrated that not only could the rate of the chemical reaction could be controlled, but directed linear chain growth within the resulting gel structure was achievable through the use of increased inhibitor concentrations. Two unique test systems have been fabricated to study the effects of varied gravity (reduced, normal, high) on the formation of titanium sol-gels. Whilst the first system is to be used in conjunction with the recently commissioned drop tower facility at Queensland University of Technology in Brisbane, Australia to produce reduced gravity conditions. The second system is a centrifuge capable of providing high gravity environments of up to 70 G's for extended periods of time. The test systems and experimental results obtained will be presented. 1. Okubo, T., Tsuchida, A., Okuda, T., Fujitsuna, K., Ishikawa, M., Morita, T., Tada, T. , Kinetic Analyses of Colloidal Crystallization in Microgravity -Aircraft Experiments. . Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999. 153: p. 515-524. 2. Okubo, T., Tsuchida, A., Kobayashi, K., Kuno, A., Morita, T., Fujishima, M., Kohno, Y., Kinetic Study of the Formation Reaction of Colloidal Silica Spheres in Microgravity Using Aircraft. Colloid Polymer Science, 1999. 277(5): p. 474-478. 3. Pienaar, C.L., Chiffoleau, G. J. A., Follens, L. R. A., Martens, J. A., Kirschhock, C. E. A., Steinberg, T. A., Effect of Gravity on the Gelation of Silica Sols. Chem. Mater., 2007. 19(4): p. 660-664. 4. Smith, D.D., et al., Effect of Microgravity on the Growth of Silica Nanostructures. Langmuir, 2000. 16(26): p. 10055-10060. 5. Zhang, X., Johnson, D.P., Manerbino, A.R., Moore, J.J., Schowengerdt, F. , Recent Mi-crogravity Results in the Synthesis of Porous Materials. AIP Conference Proceedings (Space Technology and Applications International Forum-1999, Pt. 1), 1999. 458: p. 88-93. 6. Dunbar, P.B., Bendzko, N.J.,, 1H and 13C NMR observation of the reaction of acetic acid with titanium isopropoxide. Materials Chemistry and Physics, 1999. 59: p. 26-35. 7. Krunks, M., Oja, I., T˜nsuaadu, K., Es-Souni, M., Gruselle, M., Niinistü,. L, Thermoanalytical study of acetylacetonate-modified titanium (iv) isopropoxide as precursor for TiO2 films. Journal of Thermal Analysis and Calorimetry, 2005: p. 483-488. 8. Moran, P.D., Bowmaker, G. A., Cooney, R. P., Vibrational Spectra and Molecular Associa-tion of Titanium Tetraisopropoxide. Inorg. Chem., 1998. 37(1): p. 2741-2748. 9. Somogyvari, A., Serpone, N.,, Evidence for five-coordination in titanium(1V) complexes. A nuclear magnetic resonance investigation. Canadian Journal of Chemistry, 1977. 56: p. 316-319.

  6. Sol-gel derived ceramic electrolyte films on porous substrates

    SciTech Connect

    Kueper, T.W.

    1992-05-01

    A process for the deposition of sol-gel derived thin films on porous substrates has been developed; such films should be useful for solid oxide fuel cells and related applications. Yttria-stabilized zirconia films have been formed from metal alkoxide starting solutions. Dense films have been deposited on metal substrates and ceramic substrates, both dense and porous, through dip-coating and spin-coating techniques, followed by a heat treatment in air. X-ray diffraction has been used to determine the crystalline phases formed and the extent of reactions with various substrates which may be encountered in gas/gas devices. Surface coatings have been successfully applied to porous substrates through the control of substrate pore size and deposition parameters. Wetting of the substrate pores by the coating solution is discussed, and conditions are defined for which films can be deposited over the pores without filling the interiors of the pores. Shrinkage cracking was encountered in films thicker than a critical value, which depended on the sol-gel process parameters and on the substrate characteristics. Local discontinuities were also observed in films which were thinner than a critical value which depended on the substrate pore size. A theoretical discussion of cracking mechanisms is presented for both types of cracking, and the conditions necessary for successful thin formation are defined. The applicability of these film gas/gas devices is discussed.

  7. Sol-gel hydroxyapatite coatings on stainless steel substrates.

    PubMed

    Liu, Dean-Mo; Yang, Quanzu; Troczynski, Tom

    2002-02-01

    Thin film hydroxyapatite deposits onto sandblasted 316L stainless steel substrates were prepared using water-based sol-gel technique recently developed in our lab. The coatings were annealed in air at 375 degrees C, 400 degrees C, and 500 degrees C. Phase formation, surface morphology, interfacial microstructure, and interfacial bonding strength of the coatings were investigated. Apatitic structure developed within the coatings while annealing at temperatures > or = 400 degrees C, while those heat-treated at 375 degrees C showed poor crystallinity. The coatings were dense and firmly attached to the underlying substrates, reaching an average bonding strength (as determined through the pull-out test) of 44 MPa. Nano-porous structure was found for the coatings annealed at 500 degrees C, believed to result from grain growth, and causing a slight decrease in the bonding strength. Surface microcracking, although not extensive, occurred after annealing at temperatures > or = 400 degrees C, and was linked to non-uniform thickness of the coating due to roughness of the substrate. A contraction of the coatings as a result of sintering, and phase transition from amorphous (or poor crystalline) to reasonably good crystalline apatite, may be responsible for the loss of structural integrity of the thicker sections of the coatings. It seems quite promising that a dense and adhesive apatite coating can be achieved through water-based sol gel technology after short-term annealing at around 400 degrees C in air. PMID:11771689

  8. Granulation of sol-gel-derived nanostructured alumina

    SciTech Connect

    Deng, S.G.; Lin, Y.S. [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering] [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering

    1997-02-01

    A sol-gel granulation process was developed to prepare porous nanostructured {gamma}-alumina granules as supports for catalysts and adsorbents. The process, which starts with an aqueous sol of gelatinous boehmite, involves droplet formation, gelation in paraffin oil, conditioning in ammonia solution, and drying and calcination in air under controlled conditions. The {gamma}-Al{sub 2}O{sub 3} granules prepared are 1--3 mm-dia. spherical particles with large surface area (380 m{sup 2}/g) and pore volume (0.5 cm{sup 3}/g), uniform pore-size distribution (20--60 {angstrom}), and controllable average pore size (35 {angstrom}). These sol-gel-derived granules have excellent mechanical properties with crush strength (>100 N per granule) and attrition resistance (<0.01 wt.%/h), much better than the commercial alumina and zeolite granules. Supported CuO sorbents were prepared on these granules for SO{sub 2} removal applications. The alumina-supported CuO sorbents contain higher loading of well-dispersed CuO and better sulfation properties than similar sorbents reported in the literature.

  9. Novel thermochromism in silica sol-gel materials

    NASA Astrophysics Data System (ADS)

    Gardener, Martin; Perry, Carole C.

    2000-05-01

    In this contribution we provide evidence for thermochromic color changes unique to silica based materials formed at low temperatures by the sol-gel process. The materials formed have potential application as temperature sensitive light filters, visual temperature indicators, self-diagnostic labels for electronic devices and IR recording media. The dopants, diamine complexes of copper(II)/nickel(II) chloride, change from purple to green following heating to 100 degrees C and revert to purple on cooling in the atmosphere. This color change has been explained by the substitution of water molecules by chloride ions in the first coordination sphere of the metal ions. When the same compounds are incorporated into a silica sol-gel matrix under acidic conditions the gel-glasses may be pale green, dark green, yellow, olive-yellow, blue or brown depending on the metal ion chosen and the extent of thermal treatment. Studies on the complexes themselves and on granular silicas doped with some of the complexes are assisting us in understanding the molecular mechanisms that give rise to these color changes.

  10. Transpiration cooled ultraviolet sol-gel silica optics

    NASA Astrophysics Data System (ADS)

    Seth, Vinay K.; Noques, Jean-Luc

    1991-04-01

    All rocket guidance systems essentially require broadband optical transmission windows. These windows must also be temperature insensitive to transmission, thermal shock resistant, thermally stable, reasonably strong, and impact resistant. At hypersonic velocity, convective cooling is preferred to radiative cooling. Transpiration cooling is a novel and effective mode of convective cooling. Porous silica windows offer excellent rocket windows for transpiration cooling at a relatively inexpensive price. Sol-gel technology is an enabling technology which facilitates the fabrication of these rocket windows. This research used sol-gel technology to demonstrate the concept of transpiration-cooled porous silica windows. These windows were fabricated with various pore sizes and characterized with respect to gas diffusion, transpiration, high temperature transmission, thermal stability and shock resistance, hardness, impact resistance, and strength. The manufacturability aspect was also addressed. The diffusion of various gases through porous silica windows was studied and their permeabilities measured. In the experimental range, Knusden diffusion seemed to be the predominant mass transport mechanism. At a low transpiration velocity of 0.52 cm/s of helium, a 44 C temperature drop was observed showing the promise of this material for rocket window application. High temperature spectroscopy showed improved performance. The porous silica windows had thermal stability and thermal shock resistance and reasonable mechanical properties.

  11. Synthesis of stoichiometric nano crystalline hydroxyapatite by ethanol-based sol–gel technique at low temperature

    Microsoft Academic Search

    T. Anee Kuriakose; S. Narayana Kalkura; M. Palanichamy; D. Arivuoli; Karsten Dierks; G. Bocelli; C. Betzel

    2004-01-01

    A relatively easy method to synthesize pure, stable, stoichiometric nano crystalline hydroxyapatite (Ca10(PO4)6(OH)2, HAP) at low temperature by sol–gel route is presented. Equimolar solutions of Ca(NO3)24H2O and (NH4)2HPO4 dissolved in ethanol were used in the synthesis at 85°C. The product was sintered at 400°C, 750°C and 1200°C. They were characterized by chemical analysis, XRD, FT-IR, SEM and TGA\\/DTG. The synthesized

  12. Influence of processing parameters on the luminescence of sol-gel derived PrPO{sub 4}

    SciTech Connect

    Chadeyron-Bertrand, G. [Laboratoire des Materiaux Inorganiques UMR 6002 CNRS, Universite Blaise Pascal and ENSCCF, 24 Avenue des Landais, 63177 Aubiere Cedex (France)]. E-mail: chadeyr@chimtp.univ-bpclermont.fr; Vial, S. [Laboratoire des Materiaux Inorganiques UMR 6002 CNRS, Universite Blaise Pascal and ENSCCF, 24 Avenue des Landais, 63177 Aubiere Cedex (France); Cellier, J. [Laboratoire des Materiaux Inorganiques UMR 6002 CNRS, Universite Blaise Pascal and ENSCCF, 24 Avenue des Landais, 63177 Aubiere Cedex (France); Boyer, D. [Laboratoire des Materiaux Inorganiques UMR 6002 CNRS, Universite Blaise Pascal and ENSCCF, 24 Avenue des Landais, 63177 Aubiere Cedex (France); Mahiou, R. [Laboratoire des Materiaux Inorganiques UMR 6002 CNRS, Universite Blaise Pascal and ENSCCF, 24 Avenue des Landais, 63177 Aubiere Cedex (France)

    2005-09-01

    PrPO{sub 4} synthesis by the sol-gel process was carried out using an alkoxide route. Powders purity and morphology were analyzed by means of X-ray diffraction, laser granulometry and scanning electron microscopy. Moreover, praseodymium fluorescence in that lattice was recorded by laser induced spectroscopy at room temperature. Upon excitation into the {sup 3}P{sub 0} high energy level, emission in the red wavelength range is observed from this state as well as from the {sup 1}D{sub 2} level. Finally, dependence of the phosphorus precursor and hydrolysis rate on the quantum efficiency was investigated.

  13. Optimization of sol-gel synthesis of CoFe2O4 nanowires using template assisted vacuum suction method

    NASA Astrophysics Data System (ADS)

    Pirouzfar, A.; Seyyed Ebrahimi, S. A.

    2014-12-01

    In this study, cobalt ferrite nanowires were synthesized by a sol-gel route using anodized aluminum oxide (AAO) template by applying mechanical vacuum suction. The parameters of calcination temperature and pH value were optimized subsequently. The single phase cobalt ferrite was obtained at 600 °C. The results showed that pH=1 is appropriate for synthesis of uniform nanowires because at the higher pH values the autocombustion of the gel, with making cracks in nanowires, will be happened. Furthermore, the nanowires showed higher coercivity in the direction parallel to the axis of the nanowires (Hc?=1050 Oe) rather than that in the perpendicular direction (Hc?=772 Oe).

  14. High dielectric permittivity in sol-gel derived SiO2-As2O3 glasses

    NASA Astrophysics Data System (ADS)

    Datta, A.; Giri, Anit K.; Chakravorty, D.

    1991-07-01

    Glasses in the system x As2O3(1-x) SiO2 with 0.05sol-gel route. They exhibit anomalously large dielectric permittivity in the temperature range 275 to 325 K. The permittivity values are found to be in the range 400-100 000 depending on the glass composition and the frequency of measurement. This effect is believed to arise due to a fairly large value of ratio [As5+]/[As3+] in these glasses and its drastic change as a function of temperature.

  15. Sol-Gel Precursors for Ceramics from Minerals Simulating Soils from the Moon and Mars

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Gavira-Gallardo, Jose-Antonio; Hourlier-Bahloul, Djamila

    2003-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report some preliminary results on the production of sol-gel precursors for ceramic products using mineral resources available in Martian or Lunar soil. The presence of SiO2, TiO2, and A12O3 in both Martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and Lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from Lunar and Martian simulant soils. Clear sol-gel precursors have been obtained by dissolution of silica from Lunar simulant soil in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy were used to characterize the elemental composition and structure of the precursor molecules. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors. In the second set of experiments, we used the same starting materials to synthesize silicate esters in acidified alcohol mixtures. Preliminary results indicate the presence of silicon alkoxides in the product of distillation.

  16. UV and thermally stable superhydrophobic coatings from sol–gel processing

    Microsoft Academic Search

    Yonghao Xiu; Dennis W. Hess; C. P. Wong

    2008-01-01

    A method for the preparation of inorganic superhydrophobic silica coatings using sol–gel processing with tetramethoxysilane and isobutyltrimethoxysilane as precursors is described. Incorporation of isobutyltrimethoxysilane into silica layers resulted in the existence of hydrophobic isobutyl surface groups, thereby generating surface hydrophobicity. When combined with the surface roughness that resulted from sol–gel processing, a superhydrophobic surface was achieved. This surface showed improved

  17. Glucose sensing based on the intrinsic fluorescence of sol-gel immobilized yeast hexokinase

    E-print Network

    Strathclyde, University of

    Glucose sensing based on the intrinsic fluorescence of sol-gel immobilized yeast hexokinase Faeiza of the intrinsic fluorescence of yeast hexokinase as an assay for glucose and immo- bilization of the enzyme in a silica sol-gel matrix as a potential in vivo glucose sensor for use in patients with diabetes

  18. Flow birefringence at the sol-gel transition J. F. Joanny

    E-print Network

    Paris-Sud XI, Université de

    467 Flow birefringence at the sol-gel transition J. F. Joanny Physique de la Matière Condensée fournir une experience de birefringence d'écoulement à la transition sol-gel en phase sol. Deux effets- tant. Au voisinage de la transition, la birefringence 0394n a la même divergence que la viscosité

  19. Reactions in preparing Bi4Ti3O12 ultrafine powders by sol-gel process

    Microsoft Academic Search

    Haoshuang Gu; Peizhi Chen; Youhua Zhou; Min Zhao; Anxiang Kuang; Xingjiao Li

    1998-01-01

    Bismuth titanate powders around the nanometer range have been synthesized using sol-gel process with bismuth nitrate and titanium butoxide as raw materials. The formation mechanism of sol, gel and the reactions in heat treatment process have been studied. It was found that a chelate reaction occurred in solution. In heat treatment process, the gel started to crystallize into mixture phases

  20. Sol-gel based oxidation catalyst and coating system using same

    NASA Technical Reports Server (NTRS)

    Watkins, Anthony N. (Inventor); Leighty, Bradley D. (Inventor); Oglesby, Donald M. (Inventor); Ingram, JoAnne L. (Inventor); Schryer, Jacqueline L. (Inventor)

    2010-01-01

    An oxidation catalyst system is formed by particles of an oxidation catalyst dispersed in a porous sol-gel binder. The oxidation catalyst system can be applied by brush or spray painting while the sol-gel binder is in its sol state.

  1. Enhancement of evanescent fluorescence from fiber optic sensors by thin film sol gel coatings

    SciTech Connect

    Kao, H.P.; Yang, N.; Schoeniger, J.S.

    1997-09-01

    A theoretical analysis and experimental demonstration of the increase in collected evanescent fluorescence for a fiber optic sensor having a high refractive index, titanium sol gel, thin film coating is presented. Collected fluorescence increased by up to 6 X over that from a bare fiber having a numerical aperture of 0.60. The maximum collected fluorescence increased and shifted to smaller film thicknesses as the film refractive index increased. The simulations and experimental data are consistent with a decrease in the effective refractive index of the sol gel as the film thickness increased. Electron micrographs of the sol gel structure support this observation, and show that the sol gel structure is significantly different from those on a planar glass substrate. The sol gel technique is a potentially inexpensive approach to increase the signal from fiber sensors but higher photobleaching rates at the surface are predicted.

  2. Fabrication of advanced electrochemical energy materials using sol-gel processing techniques

    NASA Technical Reports Server (NTRS)

    Chu, C. T.; Chu, Jay; Zheng, Haixing

    1995-01-01

    Advanced materials play an important role in electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. They are being used as both electrodes and electrolytes. Sol-gel processing is a versatile solution technique used in fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. The application of sol-gel processing in the fabrication of advanced electrochemical energy materials will be presented. The potentials of sol-gel derived materials for electrochemical energy applications will be discussed along with some examples of successful applications. Sol-gel derived metal oxide electrode materials such as V2O5 cathodes have been demonstrated in solid-slate thin film batteries; solid electrolytes materials such as beta-alumina for advanced secondary batteries had been prepared by the sol-gel technique long time ago; and high surface area transition metal compounds for capacitive energy storage applications can also be synthesized with this method.

  3. Vibrational spectroscopic studies of triethoxy(4-(trifluoromethyl)-phenyl) silane and its sol-gel coating

    NASA Astrophysics Data System (ADS)

    Li, Ying-Sing

    2012-10-01

    We have prepared a silica sol-gel using triethoxy (4-(trifluoromethyl)-phenyl) silane (TETFMPS) as a precursor in ethanol solution under acidic condition. The prepared sol-gel was applied to the surface treatment of aluminum for corrosion prevention. Infrared and Raman spectra of the silane coupling agent, sol-gel and sol-gel films on metal have been collected. Infrared spectroscopy has been used to study the thermal effect on the chemical composition of xerogel. Results suggested that TETFMPS molecule has a Cs point group symmetry with the plane of reflection orthogonal to the phenyl ring and the organic part of the sol-gel film remains essentially unchanged at or below 450 °C but decomposes at or above 550 °C. After the decomposition of the organic branch, the remaining film is composed of silica. Vibrational assignments were suggested by using the collected spectroscopic data in different states along with the group vibrational frequencies and other related references.

  4. Fatigue characteristic and pyroelectric properties of highly (1 1 1)-oriented Nb doped Pb(Zr 0.2,Ti 0.8)O 3 thin films with Pb 0.8La 0.1Ca 0.1Ti 0.975O 3 seed layer prepared by a sol–gel route

    Microsoft Academic Search

    Q. G. Chi; W. L. Li; X. Wang; W. D. Fei; Q. Q. Lei

    2011-01-01

    A series of highly (111)-oriented tetragonal Nb-doped Pb(Zr0.2Ti0.8)O3 (PNZT) films with and without Pb0.8La0.1Ca0.1Ti0.975O3 (PLCT) seed layer were deposited on the Pt(111)\\/Ti\\/SiO2\\/Si substrates by sol–gel processing; it was found the pyroelectric properties and fatigue resistance characteristics of PNZT films could be improved by introducing PLCT seed layer. Because the rough surface structures of 5nm-thick PLCT seed layer can offer nucleation

  5. Investigations on the photocatalytic activity of sol–gel derived plain and Fe 3+\\/Nb 5+-doped titania coatings on glass substrates

    Microsoft Academic Search

    R. Subasri; M. Tripathi; K. Murugan; J. Revathi; G. V. N. Rao; T. N. Rao

    2010-01-01

    Plain and doped (Fe3+ and Nb5+) titania coatings were deposited by dip coating on soda lime glass substrates using titania sol synthesized by sol–gel route in combination with commercial nanoparticle dispersions. The dopant concentrations were fixed at 0.07wt% and the coatings heat treated at 400°C were characterized with respect to their thickness, phase composition, hydrophilicity\\/hydrophobicity and microstructure. Photocatalytic activity testing

  6. An overview of magnetism of spinel nanoferrite particles and A study of chromium substituted Zn-Mn ferrites nanostructures via sol-gel method

    Microsoft Academic Search

    C Ramesh; Maniysundar

    2011-01-01

    In this review article, we attempt to describe the structure of various spinel ferrites like zinc ferrite, nickel-zinc ferrite, manganese-zinc ferrite and cobalt ferrite. It also describes the important magnetic properties of these spinel ferrites. The article also focused Nanocrystalline ZnMn1?xCrxFeO4 (1.0 >x > 0) ferrites which were prepared by sol-gel route. The detailed results of XRD, SAED and infrared

  7. Applications of iron (III) nitrate to obtain the multiferroic Pb(Fe 1\\/2Nb 1\\/2)O 3 ceramics by the sol–gel method

    Microsoft Academic Search

    D. Bochenek; Z. Surowiak

    2009-01-01

    In the present work the results of preparation of the multiferroic Pb(Fe1\\/2Nb1\\/2)O3 (PFN) ceramics were presented. A synthesis of the PFN ceramics powders was carried out via a wet chemical route, by the sol–gel method. The densification process of ceramic powders was made by using the free sintering method (a conventional sintering) or by the hot uniaxial pressing method.Measurements of

  8. Synthesis of Sr0.5Ba0.5Nb2O6 (SBN) thin films by sol-gel technique

    Microsoft Academic Search

    S. B. Majumder; P. S. Dobal; S. Bhaskar; R. S. Katiyar

    2000-01-01

    Tungsten bronze Sr0.5Ba0.5Nb2O6 nano-powders and thin films on platinum, Si(100), and sapphire substrates were prepared by the sol-gel route and characterized by x-ray diffraction and micro-Raman scattering techniques. The transparent and crack-free films crystallized into an orthorhombic phase at 700°C. Annealing of these films at higher temperature (? 750°C) for longer time yielded a mixture of ferroelectric tetragonal and a

  9. Solid solutions of Ni and Co molybdates in silica-dispersed and bulk catalysts prepared by sol–gel and citrate methods

    Microsoft Academic Search

    Andrea Maione; Michel Devillers

    2004-01-01

    Silica-dispersed catalysts based on cobalt, nickel and mixed Ni–Co molybdates of various compositions are prepared by a sol–gel procedure from silicon alkoxides, metal nitrates and ammonium heptamolybdate. For comparative purposes, the corresponding bulk molybdates are obtained by the citrate route. The polymorphism and the textural properties of these catalysts are investigated by means of X-ray diffraction, UV–visible diffuse reflectance spectroscopy

  10. Preparation and electrochemical characterization of LiFePO 4 nanoparticles with high rate capability by a sol–gel method

    Microsoft Academic Search

    S. B. Lee; I. C. Jang; H. H. Lim; V. Aravindan; H. S. Kim; Y. S. Lee

    2010-01-01

    The synthesis of LiFePO4 nanoparticles by an adipic acid-assisted sol–gel route has been optimized based on cycling and structural analysis. Formation of the crystalline phase was investigated through thermogravimetric-differential thermal analysis (TG-DTA). Among the optimized conditions, a 0.5 molar ratio of the adipic acid to total metal ions at a 670°C calcination temperature under an Ar atmosphere yielded LiFePO4 particles

  11. Simple Preparation of ZnO Nano-layer by Sol-Gel Method as Active Electrode in P3HT\\/ZnO Heterojunction Solar Cell

    Microsoft Academic Search

    Annisa Aprilia; Rahmat Hidayat

    2010-01-01

    Highly transparent undoped ZnO thin films have been prepared on glass and indium tin oxide substrates with simple process by sol-gel route and dip-coating deposition. Gel precursor of ZnO was prepared from zinc acetat dehydrate solution in methanol with the addition of trietylamine as stabilizing agent. Thin layer of gel precursor was prepared by dip coating and then followed by

  12. Synthesis of indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) nano-powder by sol–gel combustion hybrid method

    Microsoft Academic Search

    Chi-Hwan Han; Sang-Do Han; Jihye Gwak; S. P. Khatkar

    2007-01-01

    ITO and FTO nano-powders were synthesized employing a new route sol–gel combustion hybrid method using acetylene black as a fuel. The dried gels exhibited an auto-catalytic combustion behavior. ITO and FTO nano-powders with narrow size distribution were obtained at 750 °C. Crystal structures were examined by powder X-ray diffraction (XRD) and particle morphology as well as crystal size was investigated by

  13. Sol-gel synthesis and characterization of mesoporous manganese oxide

    SciTech Connect

    Hong Xinlin; Zhang Gaoyong; Zhu Yinyan; Yang Hengquan

    2003-10-30

    Mesoporous manganese oxide (MPMO) from reduction of KMnO{sub 4} with maleic acid, was obtained and characterized in detail. The characterization of the material was confirmed by high-resolution transmission electron microscopy (HRTEM), X-ray powder diffractometry (XRD) and N{sub 2} sorptometry. The results showed that MPMO is a pseudo-crystalline material with complex network pore structure, of which BET specific surface area is 297 m{sup 2}/g and pore size distribution is approximately in the range of 0.7-6.0 nm. The MPMO material turns to cryptomelane when the calcinating temperature rises to 400 deg. C. The optimum sol-gel reaction conditions are KMnO{sub 4}/C{sub 4}H{sub 4}O{sub 4} molar ratio=3, pH=7 and gelation time>6 h.

  14. Sol-gel synthesis of strontium pyroniobate and calcium pyroniobate

    SciTech Connect

    Prasadarao, A.V.; Selvaraj, U.; Komarneni, S.; Bhalla, A.S. (Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.)

    1992-10-01

    This paper reports on strontium and calcium pyroniobates which were prepared by a sol-gel process, using strontium/calcium metal and niobium ethoxide as precursors. The formation of Sr[sub 2]Nb[sub 2]O[sub 7] occurred at 750[degrees] C via an intermediate perovskite phase of composition close to Sr[sub 0.82]NbO[sub 3]. The crystallization of Ca[sub 2]Nb[sub 2]O[sub 7] occurred at 600[degrees] C directly without any intermediate phases. Sintered Sr[sub 2]Nb[sub 2]O[sub 7] and Ca[sub 2]Nb[sub 2]O[sub 7] pellets showed a preferred grain orientation. Microstructural studies revealed an increase in grain growth and associated orientation with sintering temperature.

  15. Dewetting of a sol-gel-derived thin film.

    PubMed

    Kwon, S Joon; Park, Jae-Gwan

    2006-04-11

    We report on the dewetting of a thin film produced by the sol-gel method. In the early stages of dynamic morphological instability, the drying stress in the capillary wave model determines the linearly scaling behaviors of the characteristic wavelength with the initial film thickness and the square law dependence of the number density of the dewetted holes on the film thickness. These power law dependences are weaker than those observed in the case of the spinodal dewetting of a polymer thin film. The wavelength determined in the early stages also dominates the scaling behaviors of the average length of the sides and number density of the polygons and the diameter of the droplets of the dewetting pattern with the film thickness in the final stages of the dynamic instability. We also observed that further drying eventually induces wrinkles in the droplets, rim, and film, which have a characteristic wavelength that can be theoretically predicted. PMID:16584272

  16. Studies on immobilized lipase in hydrophobic sol-gel.

    PubMed

    Soares, Cleide M F; dos Santos, Onelia A; de Castro, Heizir F; de Moraes, Flavio F; Zanin, Gisella M

    2004-01-01

    The hydrolysis of tetraethoxysilane using the sol-gel process was used to produce silica matrices, and these were tested for the immobilization of lipase from Candida rugosa by three methods: physical adsorption, covalent binding, and gel entrapment in the presence and absence of polyethylene glycol (PEG-1450). The silica matrices and their derivatives were characterized regarding particle size distribution, specific surface area, pore size distribution (Brunauer, Emmett, and Teller [B.E.T.] method), yield of grafting (thermogravimetric analyzer [TGA]), and chemical composition (Fourier transform infrared). Immobilization yields based on recovered lipase activity varied from 3.0 to 32.0%, and the highest efficiency was attained when lipase was encapsulated in the presence of PEG. PMID:15054215

  17. Electrochromism in sol-gel deposited TiO2 films

    NASA Astrophysics Data System (ADS)

    Bell, John M.; Barczynska, Joanna; Evans, L. A.; MacDonald, Kathleen A.; Wang, J.; Green, David C.; Smith, Geoffrey B.

    1994-09-01

    Electrochromism is sol-gel deposited TiO2 films and films containing TiO2 and WO3 has been observed. The films are deposited by dip-coating from a precursor containing titanium isopropoxide in ethanol or titanium propoxide in ethanol, and after deposition the films are heat treated to between 250 degree(s)C and 300 degree(s)C. The films do not show any signs of crystallinity. However substantial coloration is observed using Li+ ions in a non-aqueous electrolyte, both in pure TiO2 films and in mixed metal oxide films (WO3:TiO2), although the voltage required to produce coloration is different in the two cases. Results will be presented detailing the optical switching and charge transport properties of the films during cyclic voltammetry. These results will be used to compare the performance of the TiO2 films with other electrochromics. The TiO2 and mixed metal films all color cathodically, and the colored state is a neutral greyish color for TiO2, while the bleached state is transparent and colorless, Results on coloration efficiency and the stability under repeated electrochemical cycling will also be presented. The neutral color of the TiO2 films and mixed-metal films means that electrochromic windows based on TiO2 may have significant advantages over WO3-based windows. A detailed analysis of the optical properties of the colored state of the films will be presented. The dynamics of coloration for these films is also under investigation, and preliminary results will be presented.

  18. Electrochromism in sol-gel deposited TiO(sub 2) films

    SciTech Connect

    Bell, J.M.; Barczynska, J.; Evans, L.A.; MacDonald, K.A.; Wang, J.; Green, D.C.; Smith, G.B. [Univ. of Technology, Sydney, New South Wales (Australia). Dept. of Applied Physics

    1994-12-31

    Electrochromism in sol-gel deposited TiO{sub 2} films and films containing TiO{sub 2} and WO{sub 3} has been observed. The films are deposited by dip-coating from a precursor containing titanium isopropoxide in ethanol or titanium propoxide in ethanol, and after deposition the films are heat treated to between 250 C and 300 C. The films do not show any signs of crystallinity. However substantial coloration is observed using Li{sup +} ions in a non-aqueous electrolyte, both in pure TiO{sub 2} films and in mixed metal oxide films (WO{sub 3}:TiO{sub 2}), although the voltage required to produce coloration is different in the two cases. Results will be presented detailing the optical switching and charge transport properties of the films during cyclic voltammetry. These results will be used to compare the performance of the TiO{sub 2} films with other electrochromics. The TiO{sub 2} and mixed metal films all color cathodically, and the colored state is a neutral greyish color for TiO{sub 2}, while the bleached state is transparent and colorless. Results on coloration efficiency and the stability under repeated electrochemical cycling will also be presented. The neutral color of the TiO{sub 2} films and mixed-metal films means that electrochromic windows based on TiO{sub 2} may have significant advantages over WO{sub 3}-based windows. A detailed analysis of the optical properties of the colored state of the films will be presented. The dynamics of coloration for these films is also under investigation, and preliminary results will be presented.

  19. A silica sol-gel design strategy for nanostructured metallic materials.

    PubMed

    Warren, Scott C; Perkins, Matthew R; Adams, Ashley M; Kamperman, Marleen; Burns, Andrew A; Arora, Hitesh; Herz, Erik; Suteewong, Teeraporn; Sai, Hiroaki; Li, Zihui; Werner, Jörg; Song, Juho; Werner-Zwanziger, Ulrike; Zwanziger, Josef W; Grätzel, Michael; DiSalvo, Francis J; Wiesner, Ulrich

    2012-05-01

    Batteries, fuel cells and solar cells, among many other high-current-density devices, could benefit from the precise meso- to macroscopic structure control afforded by the silica sol-gel process. The porous materials made by silica sol-gel chemistry are typically insulators, however, which has restricted their application. Here we present a simple, yet highly versatile silica sol-gel process built around a multifunctional sol-gel precursor that is derived from the following: amino acids, hydroxy acids or peptides; a silicon alkoxide; and a metal acetate. This approach allows a wide range of biological functionalities and metals--including noble metals--to be combined into a library of sol-gel materials with a high degree of control over composition and structure. We demonstrate that the sol-gel process based on these precursors is compatible with block-copolymer self-assembly, colloidal crystal templating and the Stöber process. As a result of the exceptionally high metal content, these materials can be thermally processed to make porous nanocomposites with metallic percolation networks that have an electrical conductivity of over 1,000 S cm(-1). This improves the electrical conductivity of porous silica sol-gel nanocomposites by three orders of magnitude over existing approaches, opening applications to high-current-density devices. PMID:22426457

  20. A silica sol-gel design strategy for nanostructured metallic materials

    NASA Astrophysics Data System (ADS)

    Warren, Scott C.; Perkins, Matthew R.; Adams, Ashley M.; Kamperman, Marleen; Burns, Andrew A.; Arora, Hitesh; Herz, Erik; Suteewong, Teeraporn; Sai, Hiroaki; Li, Zihui; Werner, Jörg; Song, Juho; Werner-Zwanziger, Ulrike; Zwanziger, Josef W.; Grätzel, Michael; Disalvo, Francis J.; Wiesner, Ulrich

    2012-05-01

    Batteries, fuel cells and solar cells, among many other high-current-density devices, could benefit from the precise meso- to macroscopic structure control afforded by the silica sol-gel process. The porous materials made by silica sol-gel chemistry are typically insulators, however, which has restricted their application. Here we present a simple, yet highly versatile silica sol-gel process built around a multifunctional sol-gel precursor that is derived from the following: amino acids, hydroxy acids or peptides; a silicon alkoxide; and a metal acetate. This approach allows a wide range of biological functionalities and metals—including noble metals—to be combined into a library of sol-gel materials with a high degree of control over composition and structure. We demonstrate that the sol-gel process based on these precursors is compatible with block-copolymer self-assembly, colloidal crystal templating and the Stöber process. As a result of the exceptionally high metal content, these materials can be thermally processed to make porous nanocomposites with metallic percolation networks that have an electrical conductivity of over 1,000?S?cm-1. This improves the electrical conductivity of porous silica sol-gel nanocomposites by three orders of magnitude over existing approaches, opening applications to high-current-density devices.

  1. Sol-gel processes and materials. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1995-12-01

    The bibliography contains citations of selected patents concerning sol-gel processes and sol-gel derived materials and products. Selected patents include sol-gel compositions, ceramic and refractory materials, fabrication of silica glass, sol-gel thin films and coatings, transparent inorganic oxide glass, luminescent quartz glass, catalysts and catalyst supports, nuclear fuels preparation, abrasives for grinding wheels, sol-gel production of microspheres, alumina composites, photographic materials, and dental materials. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  2. Non-Shrinking Sol-Gel Type Polymers by Ring Opening Polymerizations

    SciTech Connect

    Loy, D.A.; Rahimian, K.

    1999-04-05

    We have designed a new class of cyclic siloxane compounds that behave as sol-gel systems when ring open polymerized using a hydroxide base. These monomers polymerize through chain growth polymerization. unlike conventional alkoxysilane sol-gel precursors, to form sol-gel polymers. They do not require solvent or water for polymerization, show no visible shrinkage or cracking during polymerization and are thermally stable. We have successfully utilized these materials in encapsulation of microelectronics. Current efforts are focused toward expanding this family of ROP monomers and optimization of their mechanical properties.

  3. Textured growth of multi-layered buffer layers on Ni tape by sol-gel process

    Microsoft Academic Search

    Y. Akin; Z. Aslanoglu; E. Celik; L. Arda; W. Sigmund; Y. S. Hascicek

    2003-01-01

    Textured Cerium Oxide (CeO2)\\/Yttrium-Stabilized Zirconia (YSZ)\\/CeO2 buffer layers structure were grown by sol-gel dip coating process on bi-axially textured Ni tapes for processing of YBCO coated conductors. CeO2\\/YSZ\\/CeO2 buffer layer structure has been demonstrated by vacuum techniques, but first time textured CeO2\\/YSZ\\/CeO2 structure were grown by sol-gel on biaxially textured Ni tape. The buffer layer structure promoted c-axis oriented sol-gel

  4. Calcium phosphate sol-gel-derived coatings on titanium-aluminum-vanadium substrate for biomedical applications

    NASA Astrophysics Data System (ADS)

    Gan, Lu

    Osseointegration of implants to host bone is a necessary requirement for dental and orthopaedic implants. The rate and quality of osseointegration were enhanced through the use of calcium phosphate (Ca-P) films on metallic substrates. The present study investigates the characteristics of Ca-P films applied using sol-gel dip coating methods to sintered porous-surfaced implants. Ca-P films have been formed using Inorganic Route and Organic Route processes. It has been shown that both approaches resulted in the formation of carbonated hydroxyapatite but with different Ca/P ratios as well as different surface textures and film structures, the Inorganic Route-formed film being more porous at its outermost surface, and having a more irregular topography. An interfacial reaction product (calcium titanium oxide) was detected for the Inorganic Route-formed coatings while this interfacial phase was not detectable in the Organic Route-formed coatings. The interface tensile and shear adhesion strength properties of Ca-P films have been evaluated using an improved direct pull-off testing (ASTM C633) and a substrate straining method, respectively. For both Ca-P films, the adhesive tensile strength was higher than the failure stress of ˜38 MPa occurring between the Ca-P films and the glue or in the glue. A shear lag approach revealed a shear strength of 347 +/- 64MPa and 280 +/- 28MPa for the Inorganic Route and the Organic Route Ca-P films, respectively. In vivo animal model studies have been performed to compare the effect on early bone formation of sintered porous-surfaced implants that had been modified through the addition of Ca-P film. In Group I study (i.e. Inorganic Route-formed Ca-P-coated implants vs. non-coated implants), it has been found that the Inorganic Route-formed Ca-P film significantly enhances the early rate of bone ingrowth for sintered porous-surfaced implants. However, in Group II study (i.e. Organic Route-formed Ca-P-coated implants vs. non-coated implants), significant improvement was not observed for the Organic Route-formed Ca-P film. It is speculated that the slightly different surface topography and film density between the two Ca-P films result in a different amounts of protein adsorption on the implant surface at the early stage, which further affects the following processes leading to osseointegration.

  5. Molecular receptors in metal oxide sol-gel materials prepared via molecular imprinting

    SciTech Connect

    Sasaki, D.Y.; Brinker, C.J.; Ashley, C.S.; Daitch, C.E.; Shea, K.J.; Rush, D.J.

    2000-05-02

    A method is provided for molecularly imprinting the surface of a sol-gel material, by forming a solution comprised of a sol-gel material, a solvent, an imprinting molecule, and a functionalizing siloxane monomer of the form Si(OR){sub 3{minus}n}X{sub n}, wherein n is an integer between zero and three and X is a functional group capable of reacting with the imprinting molecule, evaporating the solvent, and removing the imprinting molecule to form the molecularly imprinted metal oxide sol-gel material. The use of metal oxide sol-gels allows the material porosity, pore size, density, surface area, hardness, electrostatic charge, polarity, optical density, and surface hydrophobicity to be tailored and be employed as sensors and in catalytic and separations operations.

  6. Enhanced piezoelectric performance of composite sol-gel thick films evaluated using piezoresponse force microscopy.

    PubMed

    Liu, Yuanming; Lam, Kwok Ho; Kirk Shung, K; Li, Jiangyu; Zhou, Qifa

    2013-05-14

    Conventional composite sol-gel method has been modified to enhance the piezoelectric performance of ceramic thick films. Lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT) thick films were fabricated using the modified sol-gel method for ultrasonic transducer applications. In this work, piezoresponse force microscopy was employed to evaluate the piezoelectric characteristics of PZT and PMN-PT composite sol-gel thick films. The images of the piezoelectric response and the strain-electric field hysteresis loop behavior were measured. The effective piezoelectric coefficient (d33,eff) of the films was determined from the measured loop data. It was found that the effective local piezoelectric coefficient of both PZT and PMN-PT composite films is comparable to that of their bulk ceramics. The promising results suggest that the modified composite sol-gel method is a promising way to prepare the high-quality, crack-free ceramic thick films. PMID:23798771

  7. Preparation of oxide glasses from metal alkoxides by sol-gel method

    NASA Technical Reports Server (NTRS)

    Kamiya, K.; Yoko, T.; Sakka, S.

    1987-01-01

    An investigation is carried out on the types of siloxane polymers produced in the course of the hydrolysis of silicon tetraethoxide, as well as the preparation of oxide glasses from metal alkoxides by the sol-gel method.

  8. Molecular receptors in metal oxide sol-gel materials prepared via molecular imprinting

    DOEpatents

    Sasaki, Darryl Y. (Albuquerque, NM); Brinker, C. Jeffrey (Albuquerque, NM); Ashley, Carol S. (Albuquerque, NM); Daitch, Charles E. (Charlottesville, VA); Shea, Kenneth J. (Irvine, CA); Rush, Daniel J. (Philadelphia, PA)

    2000-01-01

    A method is provided for molecularly imprinting the surface of a sol-gel material, by forming a solution comprised of a sol-gel material, a solvent, an imprinting molecule, and a functionalizing siloxane monomer of the form Si(OR).sub.3-n X.sub.n, wherein n is an integer between zero and three and X is a functional group capable of reacting with the imprinting molecule, evaporating the solvent, and removing the imprinting molecule to form the molecularly imprinted metal oxide sol-gel material. The use of metal oxide sol-gels allows the material porosity, pore size, density, surface area, hardness, electrostatic charge, polarity, optical density, and surface hydrophobicity to be tailored and be employed as sensors and in catalytic and separations operations.

  9. Production of cerium oxide microsheres by an internal gelation sol-gel process

    E-print Network

    Wegener, Jeffrey J.

    2010-01-14

    The experiments performed for this research were completed to produce solid cerium oxide microspheres by an internal gelation sol-gel process. The motivation for this work was to develop a process that would enable the fabrication of a storage...

  10. High second-order optical nonlinearities in thermally poled sol-gel silica

    NASA Astrophysics Data System (ADS)

    Pruneri, V.; Bonfrate, G.; Kazansky, P. G.; Takebe, H.; Morinaga, K.; Kohno, M.; Kuwasaki, K.; Takeuchi, T.

    1999-05-01

    Silica glass samples prepared by a sol-gel process, the mixture of silica sol for gelation and colloidal silica particles, have been thermally poled in vacuum by continuous high voltage (8-12 kV) at elevated temperature (280 °C). High second-order nonlinearities (>1 pm/V), located under the anodic surface, have been measured and the values are higher than those obtained in fused silica glass, poled under the same conditions. A model for thermal poling is suggested which explains the experimental results in sol-gel silica and the difference between thermal poling of sol-gel and fused silica. The granular structure and the boundaries of sol-gel silica seem to play a major role in establishing the electrical properties of the depletion layer during and after poling.

  11. The physics and chemistry of semiconductor nanocrystals in sol-gel derived optical microcavities

    E-print Network

    Chan, Yinthai

    2006-01-01

    The incorporation of semiconductor nanocrystals (NCs) into sol-gel derived matrices presents both novel applications as well as a robust platform in which to investigate the nonlinear optical properties of NCs. This thesis ...

  12. Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions.

    E-print Network

    Paris-Sud XI, Université de

    1 Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions. C. Mansuy1. In order to exhibit luminescence properties, these materials are generally doped with rare earth ions. Lu

  13. Optical pH detector based on LTCC and sol-gel technologies

    NASA Astrophysics Data System (ADS)

    Tadaszak, R. J.; ?ukowiak, A.; Golonka, L. J.

    2013-01-01

    This paper presents an investigation on using sol-gel thin film as a material for sensors application in LTCC (Low Temperature Co-fired Ceramics) technology. This material gives the opportunity to make new, low-cost highly integrated optoelectronic devices. Sensors with optical detection are a significant part of these applications. They can be used for quick and safe diagnostics of some parameters. Authors present a pH detector with the optical detection system made of the LTCC material. The main part of the device is a flow channel with the chamber and sol-gel active material. The silica sol-gel with bromocresol green indicator was used. As the absorbance of sol-gel layer changes with the pH value of a measured medium, the transmitted light power was measured. The pH detector was integrated with the electronic components on the LTCC substrate.

  14. Sol-gel and microwave processing of PZT materials for sensor and actuator applications

    NASA Astrophysics Data System (ADS)

    Ounaies, Zoubeida; Varadan, Vijay K.; Varadan, Vasundara V.

    1994-05-01

    In this work, the preparation of PZT materials used for the fabrication of smart sensors and actuators is closely investigated. The sol-gel method is used for the processing of the PZT powder because of its potential for making fine, pure and homogeneous powders. Sol-gel is a chemical method that has the possibility of synthesizing a reproducible material. Microwave energy is used for the calcining of this powder and the sintering of the PZT samples. Its use for calcination has the advantage of reducing the total processing time and the soak temperature. In addition, the combination of sol-gel and microwave processing leads to smaller particles and a more uniform distribution of their sizes. Microwave sintering of sol-gel prepared PZT has been accomplished successfully and has been shown to yield improved microstructure and good properties.

  15. Heat treatment effect on the physical properties of cobalt doped TiO{sub 2} sol–gel materials

    SciTech Connect

    Samet, L., E-mail: lolwasamet@gmail.com [Institut Préparatoires aux Etudes d'Ingénieurs d'El-Manar, Université Tunis El Manar, Campus Universitaire, 2092 El Manar (Tunisia); Laboratoire de Photovoltaique de Semi-conducteur et de Nanostructure, Centre de Recherches et des Technologies de l'Energie, Technopole borj cedria, Bp 95, hammamm lif 2050 (Tunisia); Ben Nasseur, J.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteur et de Nanostructure, Centre de Recherches et des Technologies de l'Energie, Technopole borj cedria, Bp 95, hammamm lif 2050 (Tunisia); March, K.; Stephan, O. [Laboratoire de Physique des Solides, UMR 8502 CNRS - Université Paris-Sud, Bât 510, 91405 Orsay cedex (France)

    2013-11-15

    Cobalt doped and undoped TiO{sub 2} powders have been prepared by sol–gel technique and annealed at temperatures ranging from 400 °C to 1000 °C. The effects of annealing temperature on the structural, morphological and optical properties have been characterized by X-ray diffraction, transmission electron microscopy, electron energy-loss spectroscopy and diffuse reflectance spectroscopy. For all doped samples there is a general reduction of the band gap energy, in comparison with undoped samples prepared in the same conditions. More specifically, experimental results indicate that cobalt doping, occurring as Co{sup 2+} ion insertion into the TiO{sub 2} (Ti{sup 4+}) host lattice, inhibits the growth of the crystallites and delays the phase transformation from anatase to rutile. Moreover, at high temperature, a secondary phase (CoTiO{sub 3}) is found to coexist with highly crystalline rutile. These structural characteristics are discussed in relation with the observed general trends for the optical properties. - Highlights: • Cobalt doped and undoped TiO{sub 2} powders have been prepared by sol–gel route. • Doping makes the band gap narrower. • Doping delays the phase transformation from anatase to rutile. • Doping inhibits the growth of the crystallites. • At high annealing temperature a CoTiO{sub 3} phase coexists with highly crystalline rutile.

  16. Hybrid carbon silica nanofibers through sol-gel electrospinning.

    PubMed

    Pirzada, Tahira; Arvidson, Sara A; Saquing, Carl D; Shah, S Sakhawat; Khan, Saad A

    2014-12-30

    A controlled sol-gel synthesis incorporated with electrospinning is employed to produce polyacrylonitrile-silica (PAN-silica) fibers. Hybrid fibers are obtained with varying amounts of silica precursor (TEOS in DMF catalyzed by HCl) and PAN. Solution viscosity, conductivity, and surface tension are found to relate strongly to the electrospinnability of PAN-silica solutions. TGA and DSC analyses of the hybrids indicate strong intermolecular interactions, possibly between the -OH group of silica and -CN of PAN. Thermal stabilization of the hybrids at 280 °C followed by carbonization at 800 °C transforms fibers to carbon-silica hybrid nanofibers with smooth morphology and diameter ranging from 400 to 700 nm. FTIR analysis of the fibers confirms the presence of silica in the as-spun as well as the carbonized material, where the extent of carbonization is also estimated by confirming the presence of -C?C and -C?O peaks in the carbonized hybrids. The graphitic character of the carbon-silica fibers is confirmed through Raman studies, and the role of silica in the disorder of the carbon structure is discussed. PMID:25474752

  17. Sol-gel derived electrode materials for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Lin, Chuan

    1998-12-01

    Electrochemical capacitors have been receiving increasing interest in recent years for use in energy storage systems because of their high energy and power density and long cycle lifes. Possible applications of electrochemical capacitors include high power pulsed lasers, hybrid power system for electric vehicles, etc. In this dissertation, the preparation of electrode materials for use as electrochemical capacitors has been studied using the sol-gel process. The high surface area electrode materials explored in this work include a synthetic carbon xerogel for use in a double-layer capacitor, a cobalt oxide xerogel for use in a pseudocapacitor, and a carbon-ruthenium xerogel composite, which utilizes both double-layer and faradaic capacitances. The preparation conditions of these materials were investigated in detail to maximize the surface area and optimize the pore size so that more energy could be stored while minimizing mass transfer limitations. The microstructures of the materials were also correlated with their performance as electrochemical capacitors to improve their energy and power densities. Finally, an idealistic mathematical model, including both double-layer and faradaic processes, was developed and solved numerically. This model can be used to perform the parametric studies of an electrochemical capacitor so as to gain a better understanding of how the capacitor works and also how to improve cell operations and electrode materials design.

  18. Simultaneous determination of ascorbic acid and dopamine at a sol–gel composite electrode

    Microsoft Academic Search

    D. Ravi Shankaran; K. Iimura; T. Kato

    2003-01-01

    A new sol–gel composite electrode containing dispersed copper was fabricated using (3-mercaptopropyl)trimethoxysilane (MPS) and copper nitrate. The sensor exhibited excellent characteristics for simultaneous determination of ascorbic acid and dopamine owing to its combined features of sol–gel composite and copper catalysis. The peaks for the oxidation of ascorbic acid and dopamine were well resolved at the reduced potentials with good sensitivity.

  19. Characterisation of bismuth-doped yttrium iron garnet layers prepared by sol–gel process

    Microsoft Academic Search

    J.-L Rehspringer; J. Bursik; D. Niznansky; A. Klarikova

    2000-01-01

    Yttrium iron garnets and Bi-substituted yttrium iron garnets were prepared by two different sol–gel processes. We investigated the evolution with temperature of XRD patterns and of the magnetisation of powders issued from sol–gel solution decomposition. We prepared layers on silica glass by the spin- or dip-coating processes. XRD patterns on layers were also obtained. The dependency of the Faraday effect

  20. Thickness dependency of sol-gel derived ZnO thin films on gas sensing behaviors

    Microsoft Academic Search

    Nitul Kakati; Seung Hyun Jee; Su Hyun Kim; Jun Young Oh; Young Soo Yoon

    2010-01-01

    ZnO thin films were fabricated by a sol-gel method using Zn(CH3COO)2·2H2O as starting material in order to prepare an acetone gas sensor. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of ethanol and monoethanolamine. The sol-gel solution is coated on alumina substrates with various thicknesses by spin coating technique and heat treated to

  1. Characterization of pitting corrosion in bare and sol–gel coated aluminum 2024-T3 alloy

    Microsoft Academic Search

    N. Voevodin; C. Jeffcoate; L. Simon; M. Khobaib; M. Donley

    2001-01-01

    The prevention of pitting corrosion in aerospace aluminum alloys by the application of protective sol–gel coatings requires a thorough understanding of pit formation kinetics and morphology developments in such surface coating systems. This study reports results of chemical and electrochemical methods of pitting corrosion tests for bare and sol–gel coated Al 2024-T3 alloy. Specific attention is focused on the characterization

  2. Sol–gel TiO 2 antireflective films for textured monocrystalline silicon solar cells

    Microsoft Academic Search

    G. San Vicente; A. Morales; M. T. Gutiérrez

    2002-01-01

    The aim of this study is validate the sol–gel method as a procedure to prepare antireflective films (AR) for textured monocrystalline solar cells. In this way, sol–gel TiO2 films were deposited on both microscope slides and textured monocrystalline silicon solar cells by dip coating. The solutions were prepared by mixing tetrabutyl ortotitanate, water and ethanol using a basic compound as

  3. Formation and microwave absorption of barium and strontium ferrite prepared by sol-gel technique

    Microsoft Academic Search

    K. A. Hempel; D. Bonnenberg

    1993-01-01

    Ba and Sr ferrites are prepared by sol-gel technique with different Fe\\/Ba(Sr) ratios in the starting materials. Magnetization, coercive, and anisotropy field strength are determined depending on the heat treatment of the gel and the iron\\/barium(strontium) ratio in the starting material. A two-step heat treatment is used to prepare single-domain powders with high magnetization. These powders prepared by sol-gel technique

  4. Fabrication, structure and biological properties of organic acid-derived sol-gel bioactive glasses

    Microsoft Academic Search

    Bo Lei; Xiaofeng Chen; Yingjun Wang; Naru Zhao; Chang Du; Liming Fang

    2010-01-01

    Sol-gel-derived bioactive glasses (BGs) have been developed for bone tissue regeneration. To develop more reliable bone tissue repair systems, it is necessary to control the morphology and surface textures of bioactive glasses. In this study, we prepared bioactive glasses by sol-gel technology using hydrochloride acid, lactic acid, citric acid and acetic acid as hydrolysis catalysts. We studied effects of acids

  5. Synthesis and characterization of nanocrystalline tin oxide by sol–gel method

    Microsoft Academic Search

    Jianrong Zhang; Lian Gao

    2004-01-01

    Nanocrystalline SnO2 particles have been synthesized by a sol–gel method from the very simple starting material granulated tin. The synthesis leads a sol–gel process when citric acid is introduced in the solution obtained by dissolving granulated tin in HNO3. Citric acid has a great effect on stabilizing the precursor solution, and slows down the hydrolysis and condensation processes. The obtained

  6. Structural and optical properties of YAG:Ce 3+ phosphors by sol–gel combustion method

    Microsoft Academic Search

    Guodong Xia; Shengming Zhou; Junji Zhang; Jun Xu

    2005-01-01

    High-quality Ce3+-doped Y3Al5O12 (YAG:Ce3+) phosphors were synthesized by a facile sol–gel combustion method. In this sol–gel combustion process, citric acid acts as a fuel for combustion, traps the constituent cations and reduces the diffusion length of the precursors. The XRD and FT-IR results show that YAG phase can form through sintering at 900°C for 2h. This temperature is much lower

  7. Study on the hydrophobic surfaces prepared by two-step sol–gel process

    Microsoft Academic Search

    Shi-Ing Huang; Yi-Ju Shen; Hui Chen

    2009-01-01

    In this study, the two-step sol–gel process was used to prepare hydrophobic coating films on the glass substrates. The first step was to add hydrogen chloride into TEOS (tetraethoxysilane) solution, and then the second step was to add ammonia into the above reacted solution. We adopted different amount of hydrogen chloride and ammonia to control the sol–gel reaction and observed

  8. Sol–gel network silica\\/modified montmorillonite clay hybrid nanocomposites for hydrophobic surface coatings

    Microsoft Academic Search

    Kamal Mohamed Seeni Meera; Rajavelu Murali Sankar; Adhigan Murali; Sellamuthu N. Jaisankar; Asit Baran Mandal

    Sol–gel silica\\/nanoclay composites were prepared through sol–gel polymerization technique using tetraethylorthosilicate precursor and montmorillonite (MMT) clay in aqueous media. In this study, both montmorillonite-K+ and organically modified MMT (OMMT) clays were used. The prepared composites were coated on glass substrate by making 1wt% solution in ethyltrichlorosilane. The incorporation of nanoclay does not alter the intensity of characteristic Si–O–Si peak of

  9. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    Microsoft Academic Search

    Jeffrey C. S. Wu; I.-Hsiang Tseng; Wan-Chen Chang

    2001-01-01

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following

  10. Characterization of titanium alkoxide sol–gel systems designed for anti-icing coatings: I. Chemistry

    Microsoft Academic Search

    Jennifer Ayres; W. H. Simendinger; C. M. Balik

    2007-01-01

    Recent interest in sol–gel chemistry involving titanium alkoxide precursors has been prompted by the ability to control the\\u000a morphology of the final TiO2 structure. The ligands used in these processes are typically sacrificial and are removed once the process is complete. In\\u000a contrast, the sol–gel chemistry presented here is used to facilitate the slow release of the attached alkoxide ligands:

  11. Sol-Gel synthesis of an optical silica glass doped with rare-earth elements

    Microsoft Academic Search

    N. N. Khimich; G. M. Berdichevskii; E. N. Poddenezhnyi; V. V. Golubkov; A. A. Boiko; V. M. Ken’ko; O. B. Evreinov; L. A. Koptelova

    2007-01-01

    An optical quality silica glass doped with Er3+, Yb3+ and Lu3+ ions is synthesized by the sol-gel method. Virtually unavoidable clusterization of rare-earth elements that occurs upon introduction\\u000a of lanthanide salts into a sol-gel system and leads to concentration quenching of luminescence of the glass is eliminated\\u000a through the use of rare-earth phosphate complexes that are chemically bound to the

  12. Nano-replication of diffractive optical elements in sol–gel derived glasses

    Microsoft Academic Search

    V. K. Parashar; A. Sayah; M. Pfeffer; F. Schoch; J. Gobrecht; M. A. M. Gijs

    2003-01-01

    A novel technological approach to generate glass micro- and nano-structures using in-house developed sol–gel materials, PDMS molding and thermal densification procedures was developed and presented. The synthesis of our sol–gel glass materials is based on the formation of particles of controlled size from organo-metallic compounds. The overall shrinkage during annealing of the gel material is negligible and does not imply

  13. Characterization of LiTaO3 thin films fabricated by sol-gel technique

    Microsoft Academic Search

    S. Youssef; R. Al Asmar; J. Podlecki; F. Pascal-delannoy; Y. Zaatar; A. Foucaran

    2007-01-01

    Lithium tantalite (LiTaO3) thin films have been fabricated by sol–gel technique and crystallized by RTA process. The effect of heating temperature on the structural properties of LiTaO3 is investigated. The thin films are characterized by means of X-ray diffraction, Raman spectroscopy and thermal analysis (DCA\\/DTA). After the optimization of the growth parameters of LiTaO3 prepared by sol–gel processing, the pyroelectric

  14. Preparation of Pb(Zr,Ti)O3 Thin Films by Sol-Gel Technique

    Microsoft Academic Search

    Tomoyasu Takusagawa; Noriaki Yamada; Terumasa Kato; Hajime Hattori; Teruyuki Matsui

    1994-01-01

    In the preparation of Pb(Zr,Ti)O3 thin films by the sol-gel technique, the following procedures are involved: evaporation of solvents, thermal decomposition of organometallic compounds and crystallization. In this study, a thermodynamic approach was employed for the sol-gel technique, and the processing conditions were determined. For the processes of evaporation and thermal decomposition, the processing conditions were determined by applying Ozawa's

  15. Hydroxyapatite powders and thin films prepared by a sol-gel technique

    Microsoft Academic Search

    C. M. Lopatin; V. Pizziconi; T. L. Alford; T. Laursen

    1998-01-01

    The formation of hydroxyapatite (HA) from a sol-gel precursor was studied using X-ray diffraction (XRD). The sol-gel was processed into both powders and thin films. The effect of drying and firing temperatures on the HA phase formation was studied. Thin HA films up to 1 ?m thick were deposited on silicon wafers coated either with borophosphate silicate glass (BPSG) or

  16. Strength of interactions between immobilized dye molecules and sol-gel matrices.

    PubMed

    Ismail, Fanya; Schoenleber, Monika; Mansour, Rolan; Bastani, Behnam; Fielden, Peter; Goddard, Nicholas J

    2011-02-21

    In this paper we present a new theory to re-examine the immobilization technique of dye doped sol-gel films, define the strength and types of possible bonds between the immobilized molecule and sol-gel glass, and show that the immobilized molecule is not free inside the pores as was previously thought. Immobilizing three different pH sensitive dyes with different size and functional groups inside the same sol-gel films revealed important information about the nature of the interaction between the doped molecule and the sol-gel matrix. The samples were characterized by means of ultraviolet-visible spectrophotometer (UV-VIS), thermal gravimetric analysis (TGA), mercury porosimetry (MP), nuclear magnetic resonance spectroscopy ((29)Si NMR) and field-emission environmental scanning electron microscopy (ESEM-FEG). It was found that the doped molecule itself has a great effect on the strength and types of the bonds. A number of factors were identified, such as number and types of the functional groups, overall charge, size, pK(a) and number of the silanol groups which surround the immobilized molecule. These results were confirmed by the successful immobilization of bromocresol green (BCG) after a completely polymerized sol-gel was made. The sol-gel consisted of 50% tetraethoxysilane (TEOS) and 50% methyltriethoxysilane (MTEOS) (w/w). Moreover, the effect of the immobilized molecule on the structure of the sol-gel was studied by means of a leaky waveguide (LW) mode for doped films made before and after polymerization of the sol-gel. PMID:21120245

  17. Sealing of pores in sol–gel-derived tritium permeation barrier coating by electrochemical technique

    Microsoft Academic Search

    Kun Zhang; Yuji Hatano

    2011-01-01

    An electrolytic deposition technique was applied to seal open pores in sol–gel derived ZrO2 coating and to improve barrier effects against permeation of hydrogen isotopes. Disk-type specimens of type 430 ferritic stainless steel were first covered by thin ZrO2 films (50nm) with a conventional sol–gel technique. Then, pores in the ZrO2 film was sealed with ZrO2 or Al2O3 by cathodic

  18. Fluorescent porous sol-gel coatings for near-IR single-mode fiber chemical sensors

    Microsoft Academic Search

    Alexander J. Fielding; Christopher C. Davis

    1998-01-01

    Reports of enhanced photostability of organic florescent dyes when entrapped in a sol-gel matrix have led us to examine the behavior of the near-IR dye IR-125 coated onto the end of single mode optical fibers. Various fiber tip geometries were fabricated and a specially prepared rounded tip was found to be optimal for long-term adhesion of thick sol-gel coatings to

  19. Optical fibers by a hybrid process using sol–gel silica overcladding tubes

    Microsoft Academic Search

    J. B MacChesney; D. W Johnson Jr; S Bhandarkar; M. P Bohrer; J. W Fleming; E. M Monberg; D. J Trevor

    1998-01-01

    We have successfully developed a sol–gel process to produce large silica glass bodies to be used as optical fiber preform overcladding tubes which meet the demands of optical fiber. We have made and tested tubes weighing approximately 4.5 kg, which comprise about 90% of the eventual fiber's mass. This sol–gel process uses colloidal silica dispersed in high pH water. The

  20. Mechanical properties and microstructures of sol-gel derived ceramic-matrix composites

    Microsoft Academic Search

    J. M. Chant; S. M. Bleay; B. Harris; R. Russell-Floyd; R. G. Cooke; V. D. Scott

    1995-01-01

    A sol-gel process involving rapid freezing (“freeze gelation”) permits the fabrication of ceramic-matrix composite components at low sintering temperatures, to near-net shape and with low shrinkage. The effects of matrix composition and sintering temperature on the microstructures, mechanical properties and damage modes of sol-gel-silica\\/unidirectional carbon-fibre composites obtained by filament winding were explored. Matrix properties were modified by the incorporation of

  1. Evaluation and characterization of nanostructure hydroxyapatite powder prepared by simple sol–gel method

    Microsoft Academic Search

    M. H. Fathi; A. Hanifi

    2007-01-01

    Many attempts have been focused on preparing of synthetic hydroxyapatite (HA), which closely resembles bone apatite and exhibits excellent osteoconductivity. Low temperature formation and fusion of the apatite crystals have been the main contributions of the sol–gel process in comparison with conventional methods for HA powder synthesis. This paper describes the synthesis of nano-HA particles via a sol–gel method. Nanocrystalline

  2. Molecular Homogeneity in Erbium-Doped Sol-Gel Waveguide Amplifiers

    Microsoft Academic Search

    Athanasios Laliotis; E. M. Yeatman; Munir M. Ahmad; Weibin Huang

    2004-01-01

    High net gain levels have recently been reported in silica-on-silicon waveguide amplifiers, using the sol-gel method of glass deposition. Spectroscopic measurements indicate that high inversion levels are achieved at high erbium concentrations, sug- gesting a high uniformity in the erbium distribution. Here we show that high inversion and low scattering losses are only achieved in sol-gel waveguides which have had

  3. Direct laser writing of ridge optical waveguides in silica-titania glass sol-gel films

    Microsoft Academic Search

    Stefano Pelli; Giancarlo C. Righini; Antonio Scaglione; Massimo Guglielmi; Alessandro Martucci

    1996-01-01

    Sol-gel process is attracting a growing attention as a rather simple technology with potential for low-cost batch manufacture of integrated optical waveguides. Here experimental results are presented on the fabrication of silica-titania sol-gel films and on their laser densification, a technique which may be very useful for rapid circuit prototyping. Transversally multimode waveguides with propagation loss around 1 dB\\/cm have

  4. Overview of sol-gel guest-host materials chemistry for optical devices

    Microsoft Academic Search

    Mark P. Andrews

    1997-01-01

    This paper gives an overview of opportunities for sol-gel glass guest-host materials chemistry in the area of glass integrated optics, glass integrated optics on silicon, from the perspective of optical devices and components. Our discussion locates sol-gel glass processing among several available and competing processes such as flame hydrolysis deposition and chemical vapor deposition for producing glass optical devices and

  5. Comparison study from sputtering, sol-gel, and ALD processes developing embedded thin film capacitors

    Microsoft Academic Search

    Jinyong Ahn; Joseph Y. Lee; Joonsung Kim; Je Gwang Yoo; Changsup Ryu

    2006-01-01

    Three methods for fabricating thin film capacitors are investigated using sputtering, sol-gel, and atomic layer deposition (ALD) techniques for advanced packaging applications for embedded capacitors. In particular, the microstructures and the electrical properties of ceramic oxide films Au\\/Ti\\/Al2O3 for ALD are being studied while ferroelectric thin films Au\\/Ti\\/BaTiO3 for sol-gel and Cu\\/Ba1 - xSrxTiO3 for sputtering are being discussed in

  6. Characterization of a fluorescent sol–gel encapsulated erythrosin B dissolved oxygen sensor

    Microsoft Academic Search

    R. T Bailey; F. R Cruickshank; G Deans; R. N Gillanders; M. C Tedford

    2003-01-01

    A thin film dissolved oxygen sensor was fabricated by trapping erythrosin B in a sol–gel matrix. No phosphorescence was observed when the sensor was immersed in water. Very weak phosphorescence was observed when erythrosin B was dissolved in aqueous ethanol and acetone solutions. However, fluorescence at 590nm, which was efficiently quenched by dissolved oxygen, was observed from the doped sol–gel

  7. Novel hybrid sol–gel coatings for corrosion protection of AZ31B magnesium alloy

    Microsoft Academic Search

    S. V. Lamaka; M. F. Montemor; A. F. Galio; M. L. Zheludkevich; C. Trindade; L. F. Dick; M. G. S. Ferreira

    2008-01-01

    This work aims to develop and study new anticorrosion films for AZ31B magnesium alloy based on the sol–gel coating approach.Hybrid organic–inorganic sols were synthesized by copolymerization of epoxy-siloxane and titanium or zirconium alkoxides. Tris(trimethylsilyl) phosphate was also used as additive to confer additional corrosion protection to magnesium-based alloy. A sol–gel coating, about 5-?m thick, shows good adhesion to the metal

  8. Structural Stability of Azurin Encapsulated in Sol-Gel Glasses: A Fluorometric Study

    Microsoft Academic Search

    Massimo Bottini; Almerinda Di Venere; Lutz Tautz; Alessandro Desideri; Paolo Lugli; Luciana Avigliano; Nicola Rosato

    2004-01-01

    In this study we investigated the structural features of azurin, a blue copper-containing enzyme, upon encapsulation in tetramethoxysilane derived sol-gel glasses. Fluorescence spectroscopy revealed that gelation of inorganic networks does not affect the protein tertiary structure and only after two months solvent phase loss altered protein stability. In case of organically modified sol-gel matrices, the protein stability was reduced after

  9. Tribological behavior of sol–gel TiO 2 films on glass

    Microsoft Academic Search

    Wenguang Zhang; Weimin Liu; Chengtao Wang

    2002-01-01

    TiO2 thin films were grown on a glass substrate by sol–gel and dip-coating processes from specially formulated sols, followed by annealing at 460°C. Thermogravimetric analysis (TGA) and differential scanning calorimetric analysis (DSC) of dried sols were performed to explore the thermal events occurring during the annealing process of the sol–gel TiO2 films. The chemical states of some typical elements in

  10. Sol-gel-derived micron scale optical fibers for chemical sensing

    Microsoft Academic Search

    U. Narang; R. Gvishi; F. V. Bright; P. N. Prasad

    1996-01-01

    We report for the first time on the preparation of organically-doped room temperature processed sol-gel-derived micron scale optical fibers as platforms for chemical- and bio-sensors. Micron scale optical fibers are drawn from fluorescent dye-doped tetraethoxysilane (TEOS)-derived sol-gel solution processed under ambient conditions. Such a simple methodology to entrap organic and even bioactive species within the optical fiber offers many advantages

  11. Structural Modification of Sol-Gel Materials through Retro Diels-Alder Reaction

    SciTech Connect

    SHALTOUT,RAAFAT M.; LOY,DOUGLAS A.; MCCLAIN,MARK D.; PRABAKAR,SHESHASAYANA; GREAVES,JOHN; SHEA,KENNETH J.

    1999-12-08

    Hydrolysis and condensation of organically bridged bis-triethoxysilanes, (EtO){sub 3}Si-R-Si(OEt){sub 3}, results in the formation of three dimensional organic/inorganic hybrid networks (Equation 1). Properties of these materials, including porosity, are dependent on the nature of the bridging group, R. Flexible groups (akylene-spacers longer than five carbons in length) polymerize under acidic conditions to give non-porous materials. Rigid groups (such as arylene-, alkynylene-, or alkenylene) form non-porous, microporous, and macroporous gels. In many cases the pore size distributions are quite narrow. One of the motivations for preparing hybrid organic-inorganic materials is to extend the range of properties available with sol-gel systems by incorporating organic groups into the inorganic network. For example, organically modified silica gels arc either prepared by co-polymerizing an organoalkoxysilane with a silica precursor or surface silylating the inorganic gel. This can serve to increase hydrophobicity or to introduce some reactive organic functionality. However, the type and orientation of these organic functionalities is difficult to control. Furthermore, many organoalkoxysilanes can act to inhibitor even prevent gelation, limiting the final density of organic functionalities. We have devised a new route for preparing highly functionalized pores in hybrid materials using bridging groups that are thermally converted into the desired functionalities after the gel has been obtained. In this paper, we present the preparation and characterization of bridged polysilsesquioxanes with Diels-Alder adducts as the bridging groups from the sol-gel polymerization of monomers 2 and 4. The bridging groups are constructed such that the retro Diela-Alder reaction releases the dienes and leaves the dienophiles as integral parts of the network polymers. In the rigid architecture of a xerogel, this loss of organic functionality should liberate sufficient space to modify the overall porosity. Furthermore, the new porosity will be functionalized with the dienophilic olefin bridging group. We also demonstrate that by changing the type of Diels-Alder adduct used as the bridging group, we can change the temperature at which the retro-Diels-Alder reaction will occur.

  12. Glass-based confined structures fabricated by sol-gel and radio frequency sputtering

    NASA Astrophysics Data System (ADS)

    Chiappini, Andrea; Armellini, Cristina; Carpentiero, Alessandro; Vasilchenko, Iustyna; Lukowiak, Anna; Risti?, Davor; Varas, Stefano; Normani, Simone; Mazzola, Maurizio; Chiasera, Alessandro

    2014-07-01

    Some of the main results obtained in the field of glass-based photonic crystal (PC) systems using complementary techniques, such as radio frequency (RF) sputtering and sol-gel route, are presented. Initially, rare earth-activated one-dimensional PCs fabricated by RF-sputtering technique will be discussed, specifically the cavity is constituted by an Er-doped SiO active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO2/TiO2 layers. Moreover, from near infrared, transmittance and variable angle reflectance spectra have verified the presence of a stop band from 1500 to 2000 nm with a cavity resonance centered at 1749 nm at 0 deg and quality factor of 890. In the second case, a composite system based on polystyrene colloidal nanoparticles assembled and embedded in an elastomeric matrix will be presented in detail. This system has been designed as a structure that displays an iridescent green color that can be attributed to the PC effect. This feature has been exploited to create a chemical sensor; in fact optical measurements have evidenced that this system presents a different optical response as a function of the solvent applied on the surface, showing: (1) high sensitivity, (2) fast response, and (3) reversibility of the signal change.

  13. Large-area sol-gel highly-reflective coatings processed by the dipping technique

    SciTech Connect

    Belleville, P. [CEA - Centre d`Etudes de Limeil-Valenton, Saint George (France); Pegon, P. [REOSC - Groupe Sfim, St Pierre du Perray (France)

    1997-12-01

    The Centre d`Etudes de Limeil-Valenton is currently involved in a project which consists of the construction of a 2 MJ/500TW (351-nm) pulsed Nd:glass laser devoted to Inertial Confinement Fusion (ICF) research. With 240 laser beams, the proposed megajoule-class laser conceptual design necessitates 44-cm x 2 44-cm x 6-cm cavity-end mirrors (1053-nm) representing more than 50-m{sup 2} of coated area. These dielectric mirrors are made of quaterwave stacks of SiO{sub 2} and ZrO{sub 2}-PVP (PolyVinylPyrrolidone) and are prepared from colloidal suspensions (sols) using the sol-gel route. After a sustained search effort. we have prepared (SiO{sub 2}/ZrO{sub 2}-PVP){sup 10} mirrored coatings with up to 99% reflection at 1053-nm and for different incidence use. Adequate laser-conditioned damage thresholds ranging 14 - 15 J/cm{sup 2} at 1053-nm wavelength and with 3-ns pulse duration were achieved. Large-area mirrors with good coating uniformity and weak edge-effect were produced by dip-coating at room temperature and atmospheric pressure.

  14. Sol-gel SiO2 film contained Au/SiO2/quantum dot core/shell/shell nanostructures with plasmonic enhanced photoluminescence.

    PubMed

    Yang, Ping; Zhang, Lipeng; Wang, Yingzi

    2012-12-01

    A sol-gel method has been developed to fabricate functional silica film with Au/SiO2/quantum dot (QD) core/shell/shell nanostructures which exhibited plasmonic enhanced photoluminescence (PL). Au nanoparticles (NPs) were homogeneously coated with a SiO2 shell by an optimal Stöber synthesis. Hydrophobic CdSe/ZnS QDs was transferred into water phase via a ligand exchange by a thin functional SiO2 layer consisted of partially hydrolyzed 3-aminopropyltrimethoxysilane (APS) sol. The Au/SiO2/QD core/shell/shell nanostructure was created by assembling the functional SiO2-coated QDs to the SiO2-coated Au NPs while QDs transferred into water phase. Those partially hydrolyzed APS molecules play an important role for the connection between the QDs and SiO2-coated Au NPs. The Au/SiO2/QD core/shell/shell nanostructures were embedded in functional sol-gel SiO2 films fabricated via spinning and dipping coating, in which the film revealed strong surface plasmon scattering and enhanced PL. Because of the dual functionality, the film is utilizable for various applications including biological and medical sensors, optical devices, and solar cells. This technique can serve as a general route for encapsulating a variety of nanomaterials in sol-gel films. PMID:23447950

  15. Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications.

    PubMed

    Regina, Viduthalai Rasheedkhan; Søhoel, Helmer; Lokanathan, Arcot Raghupathi; Bischoff, Claus; Kingshott, Peter; Revsbech, Niels Peter; Meyer, Rikke Louise

    2012-11-01

    Enzymes with antifouling properties are of great interest in developing nontoxic antifouling coatings. A bottleneck in developing enzyme-based antifouling coatings is to immobilize the enzyme in a suitable coating matrix without compromising its activity and stability. Entrapment of enzymes in ceramics using the sol-gel method is known to have several advantages over other immobilization methods. The sol-gel method can be used to make robust coatings, and the aim of this study was to explore if sol-gel technology can be used to develop robust coatings harboring active enzymes for antifouling applications. We successfully entrapped a protease, subtilisin (Savinase, Novozymes), in a ceramic coating using a sol-gel method. The sol-gel formulation, when coated on a stainless steel surface, adhered strongly and cured at room temperature in less than 8 h. The resultant coating was smoother and less hydrophobic than stainless steel. Changes in the coating's surface structure, thickness and chemistry indicate that the coating undergoes gradual erosion in aqueous medium, which results in release of subtilisin. Subtilisin activity in the coating increased initially, and then gradually decreased. After 9 months, 13% of the initial enzyme activity remained. Compared to stainless steel, the sol-gel-coated surfaces with active subtilisin were able to reduce bacterial attachment of both Gram positive and Gram negative bacteria by 2 orders of magnitude. Together, our results demonstrate that the sol-gel method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions. PMID:23020255

  16. Diffraction gratings in sol-gel films by direct contact printing using a UV-mercury lamp

    Microsoft Academic Search

    P. Ayras; J. T. Rantala; S. Honkanen; S. B. Mendes; N. Peyghambarian

    1999-01-01

    We report on the fabrication of diffraction gratings in photosensitive sol-gel thin films by direct contact printing using a UV-mercury lamp. Titanium amplitude masks were used to replicate diffraction gratings into photosensitive sol-gel films by contact printing with an incoherent UV-light source. Gratings with 1-mm period were fabricated in sol-gel films. The diffraction efficiencies of each diffracted order were measured

  17. Diffraction gratings in sol–gel films by direct contact printing using a UV-mercury lamp

    Microsoft Academic Search

    P. Äyräs; J. T Rantala; S. Honkanen; S. B Mendes; N. Peyghambarian

    1999-01-01

    We report on the fabrication of diffraction gratings in photosensitive sol–gel thin films by direct contact printing using a UV-mercury lamp. Titanium amplitude masks were used to replicate diffraction gratings into photosensitive sol–gel films by contact printing with an incoherent UV-light source. Gratings with 1-?m period were fabricated in sol–gel films. The diffraction efficiencies of each diffracted order were measured

  18. X-Ray Spectroscopic Investigation of the Zr-Site in Thin Film Sol-Gel Surface Preparations

    Microsoft Academic Search

    R. B. Greegor; K. Y. Blohowiak; J. H. Osborne; K. A. Krienke; J. T. Cherian; F. W. Lytle

    2001-01-01

    X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) measurements were made on thin film (~1000 Å) sol-gel adhesion promoting surface treatments. These silicon\\/zirconium-containing sol-gel coatings are possible replacement processes for traditional surface preparations that use environmentally undesirable and potentially toxic materials. The sol-gels were waterborne mixtures formulated with tetra-n-propoxyzirconium (TPOZ) and a silane, either 3-glycidoxypropyl-trimethoxysilane (GTMS) or 3-aminopropyl-triethoxysilane (APS).

  19. Sol–gel immobilized short-chain poly(ethylene glycol) coating for capillary microextraction of underivatized polar analytes

    Microsoft Academic Search

    Sameer Kulkarni; Anne M. Shearrow; Abdul Malik

    2007-01-01

    Sol–gel coating with covalently bonded low-molecular-weight (MW<300Da) poly(ethylene glycol) (PEG) chains was developed for capillary microextraction (CME). The sol–gel chemistry proved effective in the immobilization of low-molecular-weight PEGs thanks to the formation of chemical bonds between the organic–inorganic hybrid sol–gel PEG coating and the fused silica capillary inner surface. This chemical anchorage provided excellent thermal and solvent stability to the

  20. Preparation and Characterization of Sol-Gel SE30Coated Silica Stationary Phase for Capillary Liquid Chromatography

    Microsoft Academic Search

    Xue Gu; Yan Wang; Xiangmin Zhang

    2005-01-01

    A sol-gel chemistry-based polymer coating approach was developed for the preparation of a novel polysiloxane-coated silica stationary phase for capillary liquid chromatography. SE-30, a commercial polysiloxane stationary phase used in gas chromatography, was incorporated into the properly designed sol solution. Then the sol-gel mixture was introduced into a silica gel-packed capillary column by pressure. A thin film of sol-gel SE-30-coating

  1. Carbon nanotube-coated solid-phase microextraction metal fiber based on sol-gel technique.

    PubMed

    Jiang, Ruifen; Zhu, Fang; Luan, Tiangang; Tong, Yexiang; Liu, Hong; Ouyang, Gangfeng; Pawliszyn, Janusz

    2009-05-29

    A novel carbon nanotube (CNT)-coated solid-phase microextraction fiber was prepared based on sol-gel technique. Commonly used fragile fused silica fiber was replaced with stainless steel wire, which made the fiber unbreakable. An approach was also proposed for batch producing, and good reproducibilities for fiber to fiber and between fibers were achieved. Experiments showed that the sol-gel-CNT fiber exhibited high thermal stability to resist 350 degrees C and excellent solvent durability in methanol and acetonitrile. Compared to commercial polydimethylsiloxane (PDMS) fiber, the sol-gel-CNT fiber represented significantly improved extraction efficiencies for both polar (phenols) and non-polar (benzene, toluene, ethylbenzene, and o-xylene) compounds. Meanwhile, no replacement effect, low carry-over and wide linear range demonstrated that the newly prepared sol-gel-CNT coating has liquid properties, which allow a relatively easy quantification procedure. Moreover, the characterization of the sol-gel-CNT coating was also evaluated with McReynold probe solutes. The results showed that the coating has better affinity for all the five types of solutes compared to commercial 7microm PDMS fiber, which suggested that the coating has the potential to be developed as GC stationary phase. PMID:19394026

  2. Electrodeposited sol-gel-imprinted sensing film for cytidine recognition on Au-electrode surface.

    PubMed

    Zhang, Zhaohui; Nie, Lihua; Yao, Shouzhuo

    2006-04-15

    A novel thin molecularly imprinted sol-gel film with specific recognition for cytidine was electrodeposited on the surface of piezoelectric quartz crystal (PQC) Au-electrode. In this method, a sufficiently negative potential was applied to the electrode surface to generate hydroxyl ions, which play the role of the catalyst for the hydrolysis and condensation of 3-(aminopropyl)trimethoxysilane (APTMS). The process of the preparation of the imprinted sol-gel film was investigated in detail by using the piezoelectric quartz crystal impedance (PQCI) technique and cyclic voltammetry. The thickness of the imprinted film was controlled easily by adjusting the applied potential and the deposited time. The binding capacity and the selectivity of the electrodeposited imprinted sol-gel film were also studied in detail by using PQCI, electrochemically impedance technique and capacitance technique. The electrodeposited imprinted sol-gel film exhibited high selectivity toward cytidine in comparison to interfering substances. The dissociation constant (K(d)) in the nanomolar range indicated a strong imprinted interaction existing between the electrodeposited sol-gel-imprinted film and the template cytidine. PMID:18970586

  3. A comparative synthesis and physicochemical characterizations of Ni/Al2O3-MgO nanocatalyst via sequential impregnation and sol-gel methods used for CO2 reforming of methane.

    PubMed

    Aghamohammadi, Sogand; Haghighi, Mohammad; Karimipour, Samira

    2013-07-01

    Carbon dioxide reforming of methane is an interesting route for synthesis gas production especially over nano-sized catalysts. The present research deals with catalyst development for dry reforming of methane with the aim of reaching the most stable catalyst. Effect of preparation method, one of the most significant variables, on the properties of the catalysts was taken in to account. The Ni/Al2O3-MgO catalysts were prepared via sol-gel and sequential impregnation methods and characterized with XRD, FESEM, EDAX, BET and FTIR techniques. The reforming reactions were carried out using different feed ratios, gas hourly space velocities (GHSV) and reaction temperatures to identify the influence of operational variables. FESEM images indicate uniform particle size distribution for the sample synthesized with sol-gel method. It has been found that the sol-gel method has the potential to improve catalyst desired properties especially metal surface enrichment resulting in catalytic performance enhancement. The highest yield of products was obtained at 850 degrees C for both of the catalysts. During the 10 h stability test, CH4 and CO2 conversions gained higher values in the case of sol-gel made catalyst compared to impregnated one. PMID:23901507

  4. Ultrapure glass optical waveguide development in microgravity by the sol-gel process

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.; Holman, R. A.

    1981-01-01

    Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process referred to here is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation. The use of gels offers several advantages such as high purity and lower melting times and temperatures. The sol-gel process is studied for utilization in the preparation of multicomponent ultrapure glass batches for subsequent containerless melting of the batches in space to prepare glass blanks for optical waveguides.

  5. Thin film porous membranes based on sol-gel chemistry for catalytic sensors

    SciTech Connect

    Hughes, R.C.; Patel, S.V.; Jenkins, M.W.; Boyle, T.J.; Gardner, T.J.; Brinker, C.J.

    1998-05-01

    Nanoporous sol-gel based films are finding a wide variety of uses including gas separations and supports for heterogeneous catalysts. The films can be formed by spin or dip coating, followed by relatively low temperature annealing. The authors used several types of these films as coatings on the Pd alloy thin film sensors they had previously fabricated and studied. The sol-gel films have little effect on the sensing response to H{sub 2} alone. However, in the presence of other gases, the nanoporous film modifies the sensor behavior in several beneficial ways. (1) They have shown that the sol-gel coated sensors were only slightly poisoned by high concentrations of H{sub 2}S while uncoated sensors showed moderate to severe poisoning effects. (2) For a given partial pressure of H{sub 2}, the signal from the sensor is modified by the presence of O{sub 2} and other oxidizing gases.

  6. High-energy-density sol-gel thin film based on neat 2-cyanoethyltrimethoxysilane.

    PubMed

    Kim, Yunsang; Kathaperumal, Mohanalingam; Smith, O'Neil L; Pan, Ming-Jen; Cai, Ye; Sandhage, Kenneth H; Perry, Joseph W

    2013-03-13

    Hybrid organic-inorganic sol-gel dielectric thin films from a neat 2-cyanoethyltrimethoxysilane (CNETMS) precursor have been fabricated and their permittivity, dielectric strength, and energy density characterized. CNETMS sol-gel films possess compact, polar cyanoethyl groups and exhibit a relative permittivity of 20 at 1 kHz and breakdown strengths ranging from 650 V/?m to 250 V/?m for film thicknesses of 1.3 to 3.5 ?m. Capacitors based on CNETMS films exhibit extractable energy densities of 7 J/cm(3) at 300 V/?m, as determined by charge-discharge and polarization-electric field measurements, as well as an energy extraction efficiency of ~91%. The large extractable energy resulting from the linear dielectric polarization behavior suggests that CNETMS films are promising sol-gel materials for pulsed power applications. PMID:23427818

  7. Tantalum-Tungsten Oxide Thermite Composite Prepared by Sol-Gel Synthesis and Spark Plasma Sintering

    SciTech Connect

    Cervantes, O; Kuntz, J; Gash, A; Munir, Z

    2009-02-13

    Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO{sub 3}) energetic composite was consolidated to a density of 9.17 g.cm{sup -3} or 93% relative density. In addition those parts were consolidated without significant pre-reaction of the constituents, thus the sample retained its stored chemical energy.

  8. Tantalum-tungsten oxide thermite composites prepared by sol-gel synthesis and spark plasma sintering

    SciTech Connect

    Kuntz, Joshua D.; Gash, Alexander E. [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Cervantes, Octavio G. [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Chemical Engineering and Materials Science, University of California-Davis, One Shields Ave., Davis, CA 95616 (United States); Munir, Zuhair A. [Chemical Engineering and Materials Science, University of California-Davis, One Shields Ave., Davis, CA 95616 (United States)

    2010-08-15

    Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and the results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High-Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta-WO{sub 3}) energetic composite was consolidated to a density of 9.17 g cm{sup -3} or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy. (author)

  9. Laser-assisted sol-gel growth and characteristics of ZnO thin films

    SciTech Connect

    Kim, Min Su; Kim, Soaram [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae 621-749 (Korea, Republic of); Leem, Jae-Young [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae 621-749 (Korea, Republic of); Department of Nano Engineering, Inje University, Gimhae 621-749 (Korea, Republic of)

    2012-06-18

    ZnO thin films were grown on Si(100) substrates by a sol-gel method assisted by laser beam irradiation with a 325 nm He-Cd laser. In contrast to conventional sol-gel ZnO thin films, the surface morphology of the laser-assisted sol-gel thin films was much smoother, and the residual stress in the films was relaxed by laser irradiation. The luminescent properties of the films were also enhanced by laser irradiation, especially, by irradiation during the deposition and post-heat treatment stages. The incident laser beam is thought to play several roles, such as annihilating defects by accelerating crystallization during heat treatment, enhancing the surface migration of atoms and molecules, and relaxing the ZnO matrix structure during crystallization.

  10. Optical activation of Si nanowires using Er-doped, sol-gel derived silica

    SciTech Connect

    Suh, Kiseok; Shin, Jung H.; Park, Oun-Ho; Bae, Byeong-Soo; Lee, Jung-Chul; Choi, Heon-Jin [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon (Korea, Republic of); Department of Materials Science and Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon (Korea, Republic of); Materials Science and Technology Division, Korea Institute of Science and Technology (KIST), P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); School of Advanced Materials Science and Engineering, Yonsei University, Yonsei, 120-74 (Korea, Republic of)

    2005-01-31

    Optical activation of Si nanowires (Si-NWs) using sol-gel derived Er-doped silica is investigated. Si-NWs of about 100 nm diameter were grown on Si substrates by the vapor-liquid-solid method using Au catalysts and H{sub 2} diluted SiCl{sub 4}. Afterwards, Er-doped silica sol-gel solution was spin-coated, and annealed at 950 deg. C in flowing N{sub 2}/O{sub 2} environment. Such Er-doped silica/Si-NWs nanocomposite is found to combine the advantages of crystalline Si and silica to simultaneously achieve both high carrier-mediated excitation efficiency and high Er{sup 3+} luminescence efficiency while at the same time providing high areal density of Er{sup 3+} and easy current injection, indicating the possibility of developing sol-gel activated Si-NWs as a material platform for Si-based photonics.

  11. A sol-gel-derived acetylcholinesterase microarray for nanovolume small-molecule screening.

    PubMed

    Monton, Maria Rowena N; Lebert, Julie M; Little, Jessamyn R L; Nair, Jerald James; McNulty, James; Brennan, John D

    2010-11-15

    A fluorimetric acetylcholinesterase (AChE) assay was developed and characterized both in solution and with the enzyme entrapped in sol-gel-derived silica. The assay is based on a disulfide-thiol interchange reaction between the intramolecularly quenched dimeric dye BODIPY FL l-cystine and thiocholine generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh), which results in a brightly fluorescent monomeric product owing to the cleavage of the disulfide-coupled form of the dye. The new assay was validated by comparison with the Ellman assay performed under parallel conditions and was used in both kinetic and end point assays. The assay was extended to the fabrication of functional AChE microarrays using contact pin-printing of sol-gel-derived silica. A total of 392 sol-gel formulations were screened for gelation times and 192 of these were further evaluated for array fabrication on four different surfaces using a factor analysis approach. Of these, 66 sol-gel/surface combinations produced robust microarrays, while 26 sol-gel/surface combinations were identified that could produce highly active AChE microarrays. The Z' factor for the on-array assay using an optimal sol-gel/surface combination, which considers both signal variability and difference in signals between positive and negative controls, was determined to be 0.60, which is above the minimum level required for applicability to screening. By overprinting nanoliter volumes of solutions containing the dye, ATCh, and potential inhibitors, these microarrays could be used to screen two libraries of small molecules, one composed of newly synthesized alkaloids and another consisting of ?1000 known bioactive compounds, both as discrete compounds and mixtures thereof, for activity against AChE. IC(50) values were obtained on microarrays for compounds showing significant inhibitory activity, demonstrating the utility of arrays for quantitative inhibition assays. PMID:20949898

  12. Sol-gel deposited electrochromic films for electrochromic smart window glass

    SciTech Connect

    Oezer, N. [Istanbul Univ. (Turkey). Faculty of Science; Lampert, C.M. [Star Science (United States); Rubin, M. [Lawrence Berkeley National Lab., CA (United States). Environmental Energy Technologies Div.

    1996-08-01

    Electrochromic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these windows. The sol-gel process offers a low-capital investment for the deposition of these active films. Sol-gel serves as an alternative to more expensive vacuum deposition processes. The sol-gel process utilizes solution coating followed by a hydrolysis and condensation. In this investigation the authors report on tungsten oxide and nickel oxide films made by the sol-gel process for electrochromic windows. The properties of the sol-gel films compare favorably to those of films made by other techniques. A typical laminated electrochromic window consists of two glass sheets coated with transparent conductors, which are coated with the active films. The two sheets are laminated together with an ionically conductive polymer. The range of visible transmission modulation of the tungsten oxide was 60% and for the nickel oxide was 20%. The authors used the device configuration of glass/SnO{sub 2}:F/W0{sub 3}/polymer/Li{sub Z}NiO{sub x}H{sub y}/SnO{sub 2}:F glass to test the films. The nickel oxide layer had a low level of lithiation and possibly contained a small amount of water. Lithiated oxymethylene-linked poly(ethylene oxide) was used as the laminating polymer. Commercially available SnO{sub 2}:F/glass (LOF-Tec glass) was used as the transparent conducting glass. The authors found reasonable device switching characteristics which could be used for devices.

  13. Inorganic-based sol–gel synthesis of nano-structured LiFePO 4 \\/C composite materials for lithium ion batteries

    Microsoft Academic Search

    Jun Ma; Baohua Li; Hongda Du; Chengjun Xu; Feiyu Kang

    An inorganic and non-toxic compounds combination of FeCl2·4H2O, Li2CO3 and H3PO4 was chosen to synthesize homogeneous nano-structured LiFePO4\\/C composite material via a simplified sol–gel route. The dependency of the physicochemical properties and the corresponding\\u000a electrochemical responses on the residual carbon content were investigated in details. Rietveld refinement of X-ray diffraction\\u000a measurement and X-ray photoelectron spectroscopy analysis confirmed the feasibility of

  14. Surfactant-Assisted Sol-Gel Auto-Combustion Synthesis of SR-HEXAFERRITE Nanopowder Using Different Fuels and Basic Agents

    NASA Astrophysics Data System (ADS)

    Ghobeiti Hassab, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

    In this research Sr-hexaferrite powder was synthesized by a sol-gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N-decyltrimethylammonium bromide (C13H30BrN) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800 °C respectively, in the presence of citric acid, trimethylamine and surfactant.

  15. Surfactant-Assisted Sol-Gel Auto-Combustion Synthesis of Sr-Hexaferrite Nano-Crystalline Powder Using Different Fuels and Basic Agents

    NASA Astrophysics Data System (ADS)

    Ebrahimi, S. A. S.; Hasab, M. G.; Badiei, A.

    2010-03-01

    In this research Sr-hexaferrite powder was synthesized by a sol-gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N-decyltrimethylammonium bromide (C13H30BrN) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800° C respectively, in the presence of citric acid, trimethylamine and surfactant.

  16. Ionic conductivity of Bi{sub 2}Ni{sub x}V{sub 1?x}O{sub 5.5?3x/2} (0.1 ? x ? 0.2) oxides prepared by a low temperature sol-gel route

    SciTech Connect

    Rusli, Rolan; Patah, Aep, E-mail: ismu@chem.itb.ac.id; Prijamboedi, Bambang, E-mail: ismu@chem.itb.ac.id; Ismunandar, E-mail: ismu@chem.itb.ac.id [Inorganic and Physical Chemistry Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Abrahams, Isaac [Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2014-03-24

    Solid oxides fuel cells (SOFCs) is one technology that could contribute toward future sustainable energy. One of the most important components of an SOFC is the electrolyte, which must have high ionic conductivity. Cation substitution of vanadium in Bi{sub 4}V{sub 2}O{sub 11} yields a family of fast oxide ion conducting solids known collectively as the BIMEVOXes (bismuth metal vanadium oxide), which have the potential to be applied as electrolytes in SOFCs. The purpose of this work is to study the effect of Ni concentration, when used as a dopant, on the ionic conductivity of Bi{sub 2}Ni{sub x}V{sub 1?x}O{sub 5.5?3x/2} (BINIVOX) oxides (0.1 ? x ? 0.2) when prepared by a sol gel method. The gels were calcined at 600 °C for 24 h to produce pure BINIVOX. These oxides were found to exhibit the ?-phase structure with tetragonal symmetry in space group I4/mmm. Ionic conductivity of BINIVOX at 300 °C were 6.9 × 10{sup ?3} S cm{sup ?1}, 1.2 × 10{sup ?3} S cm{sup ?1}, and 8.2 × 10{sup ?4} S cm{sup ?1}, for x = 0.1; 0.15; and 0.2; respectively; and at 600 °C were 1.1 × 10{sup ?1} S cm{sup ?1}, 5.3 × 10{sup ?2} S cm{sup ?1}, and 2.8 ×10{sup ?2} S cm{sup ?1}, for x = 0.1; 0.15; and 0.2; respectively.

  17. Synthesis of superhydrophobic alumina membrane: Effects of sol-gel coating, steam impingement and water treatment

    NASA Astrophysics Data System (ADS)

    Ahmad, N. A.; Leo, C. P.; Ahmad, A. L.

    2013-11-01

    Ceramic membranes possess natural hydrophilicity thus tending to absorb water droplets. The absorption of water molecules on membrane surface reduces their application in filtration, membrane distillation, osmotic evaporation and membrane gas absorption. Fluoroalkylsilane (FAS) grafting allows the conversion of hydrophilic ceramic membranes into superhydrophobic thin layer, but it usually introduces a great increment of mass transfer resistance. In this study, superhydrophobic alumina membranes were synthesized by dip coating alumina support into sol-gel and grafted with the fluoroalkylsilane (FAS) named (heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane. Steam impingement and water treatment acted as additional steps to generate surface roughness on sol-gel and most importantly to reduce mass transfer resistance. Superhydrophobic alumina membrane with high water contact angle (158.4°) and low resistance (139.5 ± 24.9 G m-1) was successfully formed when the alumina membrane was dip coated into sol-gel for 7 s, treated with steam impingement for 1 min and immersed in hot water at 100 °C. However, the mass transfer resistance was greatly induced to 535.6 ± 23.5 G m-1 when the dip coating time was increased to 60 s. Long dip coating time contributes more on the blockage of porous structure rather than creates a thin film on the top of membrane surface. Reducing the pore size and porosity significantly due to increase of coating molecules deposited on the membrane. Steam impingement for 1 min promoted the formation of cones and valleys on the sol-gel, but the macro-roughness was destroyed when the steam impingement duration was extended to more than 3 min. The immersions of membranes into hot water at temperatures higher than 60 °C encouraged the formation of boehmite which enhances the formation of additional roughness and enlarges pore size greatly. Thus, this work showed that the formation of superhydrophobic alumina membrane with low resistance is influenced by three factors; sol-gel dip coating time, steam impingement time and temperature of water treatment. The optimum dip coating time could promote appropriate thickness of the sol-gel layer on the membrane support. The highest surface roughness and porosity could be created when the sol-gel layer was further treated with optimum steam impingement duration and immersed in hot water at 100 °C. The presence of appropriate sol-gel thickness can reduce the penetration of FAS during the grafting and reduce the membrane resistance.

  18. Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

    Microsoft Academic Search

    Kai Jiang; Jian Meng; Zhiqi He; Yufang Ren; Qiang Su

    1999-01-01

    A series of solid electrolytes (Ce0.8RE0.2)1\\u000a xMxO2-?(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at\\u000a 800°C. The synthesis temperature by the sol-gel methods was about 700°C lower than by the traditional ceramic method. The\\u000a electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased

  19. Site selective generation of sol-gel deposits in layered bimetallic macroporous electrode architectures.

    PubMed

    Lalo, Hélène; Bon-Saint-Côme, Yémima; Plano, Bernard; Etienne, Mathieu; Walcarius, Alain; Kuhn, Alexander

    2012-02-01

    The elaboration of an original composite bimetallic macroporous electrode containing a site-selective sol-gel deposit is reported. Regular colloidal crystals, obtained by a modified Langmuir-Blodgett approach, are used as templates for the electrogeneration of the desired metals in the form of a well-defined layered bimetallic porous electrode. This porous matrix shows a spatially modulated electroactivity which is subsequently used as a strategy for targeted electrogeneration of a sol-gel deposit, exclusively in one predefined part of the porous electrode. PMID:22260622

  20. Tribological performance of fluoroalkylsilane modification of sol–gel TiO 2 coating

    Microsoft Academic Search

    Yong Wan; Wenliu Chao; Yifang Liu; Junyan Zhang

    2011-01-01

    This paper explores the possibility of making coatings with super friction-reducing and wear protection properties by using\\u000a both sol–gel and self-assembling techniques. The thin film of TiO2 was firstly prepared on glass substrates via a sol–gel method, followed by sintering at 480°C. The self-assembled monolayer\\u000a of Fluoroalkylsilane (FAS) were then prepared on TiO2 thin film to obtain TiO2–FAS dual-layer film.

  1. Ion-irradiation-induced densification of zirconia sol-gel thin films

    SciTech Connect

    Levine, T.E.; Giannelis, E.P. [Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering; Kodali, P.; Tesmer, J.; Nastasi, M. [Los Alamos National Lab., NM (United States); Mayer, J.W. [Arizona State Univ., Tempe, AZ (United States)

    1994-02-01

    We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.

  2. Capacitance spectroscopy of alumina sol–gel capacitors with Al top contacts

    Microsoft Academic Search

    Patrick De Visschere; Karel Vanbesien

    2008-01-01

    We measured the complex capacitance C(f) of ITO\\/sol–gel alumina\\/Al capacitors deposited on glass (and some on stainless steel foil) in the frequency range 15 Hz–10 MHz.\\u000a The sol–gel films were deposited by dip-coating and following a two-step process. The capacitance C(f) found was much higher than that of a pure Al2O3-film due to the remaining porosity of the film and the uptake

  3. Novel Sol-Gel Based Pt Nanocluster Catalysts for Propane Dehydrogenation

    SciTech Connect

    Boespflug, Elaine; Kawola, Jeffrey S.; Martino, Anthony; Sault, Allen G.

    1999-08-09

    We report propane dehydrogenation behavior of catalysts prepared using two novel synthesis strategies that combine inverse micelle Pt nanocluster technology with silica and alumina sol-gel processing. Unlike some other sol-gel catalyst preparations. Pt particles in these catalysts are not encapsulated in the support structure and the entire Pt particle surface is accessible for reaction. Turnover frequencies (TOF) for these catalysts are comparable to those obtained over Pt catalysts prepared by traditional techniques such as impregnation, yet the resistance to deactivation by carbon poisoning is much greater in our catalysts. The deactivation behavior is more typical of traditionally prepared PtSn catalysts than of pure Pt catalysts.

  4. Piezoelectric thick film ultrasonic transducers fabricated by a sol-gel spray technique.

    PubMed

    Kobayashi, M; Olding, T R; Sayer, M; Jen, C K

    2002-10-01

    Thick film broadband ultrasonic transducers (UTs) produced by a sol-gel spray technique and operated below 10 MHz are presented. These UTs are formed by dispersing PZT and LiTaO3 particles, respectively in Al2O3 and PZT sol-gel solution. The 50-100 microm thick films have been deposited on curved steel, flat steel and aluminum substrates and steel rods. Ultrasonic pulse-echo signals with a signal to noise ratio of more than 25 dB are experimentally obtained for the operating temperatures up to 250 degrees C. PMID:12479598

  5. Zinc oxide films prepared by sol–gel spin coating technique

    Microsoft Academic Search

    Sharul Ashikin Kamaruddin; Kah-Yoong Chan; Ho-Kwang Yow; Mohd Zainizan Sahdan; Hashim Saim; Dietmar Knipp

    2011-01-01

    Zinc oxide (ZnO) thin films and micro- and nanostructures are very promising candidates for novel applications in emerging\\u000a thin-film transistors, solar cells, sensors and optoelectronic devices. In this paper, a low-cost sol–gel spin coating technique\\u000a was used to fabricate ZnO films on glass substrates. The sol–gel fabrication process of the ZnO films is described. The influence\\u000a of precursor concentration on

  6. Silica/quercetin sol–gel hybrids as antioxidant dental implant materials

    NASA Astrophysics Data System (ADS)

    Catauro, Michelina; Papale, Ferdinando; Bollino, Flavia; Piccolella, Simona; Marciano, Sabina; Nocera, Paola; Pacifico, Severina

    2015-06-01

    The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing the onset of peri-implant diseases. In this context, quercetin, a naturally occurring flavonoid, has been entrapped at different weight percentages in a silica-based inorganic material by a sol–gel route. The establishment of hydrogen bond interactions between the flavonol and the solid matrix was ascertained by Fourier transform infrared spectroscopy. This technique also evidenced changes in the stretching frequencies of the quercetin dienonic moiety, suggesting that the formation of a secondary product occurs. Scanning electron microscopy was applied to detect the morphology of the synthesized materials. Their bioactivity was shown by the formation of a hydroxyapatite layer on sample surface soaked in a fluid that simulates the composition of human blood plasma. When the potential release of flavonol was determined by liquid chromatography coupled with ultraviolet and electrospray ionization tandem mass spectrometry techniques, the eluates displayed a retention time that was 0.5 min less than quercetin. Collision-activated dissociation mass spectrometry and untraviolet-visible spectroscopy were in accordance with the release of a quercetin derivative. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods, whereas the 2,7-dichlorofluorescein diacetate assay highlighted their ability to inhibit the H2O2-induced intracellular production of reactive oxygen species in NIH-3T3 mouse fibroblast cells. Data obtained, along with data gathered from the MTT cytotoxicity test, revealed that the materials that entrapped the highest amount of quercetin showed notable antioxidant effectiveness.

  7. Dynamic light scattering studies on the sol-gel transition of a suspension of anisotropic colloidal particles

    E-print Network

    Sprik, Rudolf

    Dynamic light scattering studies on the sol-gel transition of a suspension of anisotropic colloidal light scattering study on the sol-gel transition of a suspension of disk-shaped colloidal particles in the neighborhood of the tran- sition can be studied best by using the noninvasive technique of light scattering

  8. Characterization and Scintillation properties of Sol-Gel derived Lu2SiO5:Ln3+

    E-print Network

    Paris-Sud XI, Université de

    Lu2SiO5 (LSO) powders. Ce3+ , Eu3+ and Tb3+ doped LSO powders have been synthesized by an original, confirming the potentiality of the sol-gel derived LSO. Keywords : Scintillation, LSO, sol-gel, medical by Melcher and Schweitzer in 1992 [1,2], lutetium oxyorthosilicate Lu2SiO5 (LSO) has presented a great

  9. Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions.

    E-print Network

    Boyer, Edmond

    Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions. C. Mansuy-669" DOI : 10.1016/j.tsf.2005.12.235 #12;Abstract Rare earth doped LuBO3 thin films have been prepared, 81.20. Fw, Keywords : Sol-Gel, Scintillators, XPS, RBS, Rare earth ions, Luminescence hal-00154764

  10. Environmentally benign sol-gel antifouling and foul-releasing coatings.

    PubMed

    Detty, Michael R; Ciriminna, Rosaria; Bright, Frank V; Pagliaro, Mario

    2014-02-18

    Biofouling on ships and boats, characterized by aquatic bacteria and small organisms attaching to the hull, is an important global issue, since over 80000 tons of antifouling paint is used annually. This biofilm, which can form in as little as 48 hours depending on water temperature, increases drag on watercraft, which greatly reduces their fuel efficiency. In addition, biofouling can lead to microbially induced corrosion (MIC) due to H2S formed by the bacteria, especially sulfate-reducing bacteria. When the International Maritime Organization (IMO) international convention banned the use of effective but environmentally damaging coatings containing tributyl tin in 2008, the development of clean and effective antifouling systems became more important than ever. New nonbiocidal coatings are now in high demand. Scientists have developed new polymers, materials, and biocides, including new elastomeric coatings that they have obtained by improving the original silicone (polydimethylsiloxane) formulation patented in 1975. However, the high cost of silicones, especially of fluoropolymer-modified silicones, has generally prevented their large-scale diffusion. In 2009, traditional antifouling coatings using cuprous oxide formulated in copolymer paints still represented 95% of the global market volume of anti-fouling paints. The sol-gel nanochemistry approach to functional materials has emerged as an attractive candidate for creating low fouling surfaces due to the unique structure and properties of silica-based coatings and of hybrid inorganic-organic silicas in particular. Sol-gel formulations easily bind to all types of surfaces, such as steel, fiberglass, aluminum, and wood. In addition, they can cure at room temperature and form thin glassy coatings that are markedly different from thick silicone elastomeric foul-releasing coatings. Good to excellent performance against biofouling, low cure temperatures, enhanced and prolonged chemical and physical stability, ease of application, and the waterborne nature of sol-gel coatings all support the diffusion of these paints to efficiently reduce the accumulation of fouling layers on valued surfaces immersed in marine or fluvial waters. Furthermore, sol-gel glassy coatings are transparent and can be effectively applied to optical devices, windows, and solar panels used in lake, fluvial, or marine environments. Sol-gel technology is eminently versatile, and the first generation sol-gel paints have already shown good performance. Even so, vast opportunities still exist for chemists to develop novel sol-gel derived coatings to both prevent biofouling and enhance the hydrodynamic properties of boat and ship hulls. Moreover, researchers have prepared and applied multifunctional sol-gel coatings providing protection against both biofouling and corrosion. They have tested these in the marine environment with good preliminary results. In this Account, we discuss some of our new strategies for the controlled functionalization of surfaces for the development of efficient antifouling and foul-releasing systems and summarize the main achievements with biocidal and nonbiocidal sol-gel coatings. We conclude by giving insight into the marine coatings and sol-gel products markets, providing arguments to justify our conclusion that the sol-gel coatings technology is now a mature platform for the development of economically viable and environmentally friendly antifouling and foul-release formulations of enhanced performance. PMID:24397288

  11. Formation of ZnO@Cd(OH) 2 core-shell nanoparticles by sol–gel method: An approach to modify surface chemistry for stable and enhanced green emission

    Microsoft Academic Search

    Rupali Mishra; Raghvendra S. Yadav; Avinash C. Pandey; Sharda. S. Sanjay; Chitra Dar

    2010-01-01

    We report the formation of highly stable and luminescent ZnO@Cd(OH)2 core-shell nanoparticles by simple introduction of cadmium salt in the initial precursor solution, used to synthesize ZnO nanoparticles by sol–gel route. The cadmium to zinc salt concentration ratio has been also varied to control the growth of ZnO nanoparticles at the smaller particle size. Formation of ZnO@Cd(OH)2 core-shell nanostructure has

  12. Synthesis and magnetic properties of quasi-single domain M-type barium hexaferrite powders via sol–gel auto-combustion: Effects of pH and the ratio of citric acid to metal ions (CA\\/M)

    Microsoft Academic Search

    Liu Junliang; Zhang Wei; Guo Cuijing; Zeng Yanwei

    2009-01-01

    Quasi-single magnetic domain M-type barium hexaferrite powders have been synthesized via sol–gel auto-combustion route, followed by secondary heating treatment at 800°C for 4h, using barium nitrate, ferrite nitrate, ammonium nitrate, citric acid, and ammonia solution as the starting materials. The auto-combustion producing powders were ?-Fe2O3 and BaCO3 with aid of additional ammonium nitrate to increase the combustion temperature. The influences

  13. Stress effects in sol-gel derived ferroelectric thin films L. Lian and N. R. Sottosa)

    E-print Network

    Sottos, Nancy R.

    Stress effects in sol-gel derived ferroelectric thin films L. Lian and N. R. Sottosa) Department 26 August 2003; accepted 19 October 2003 Residual stress development during processing of sol investigates the effects of stress on field-induced polarization switching in ferroelectric Pb Zr0.52Ti0.48)O3

  14. Biocompatibility and Reduced Drug Absorption of Sol-Gel-Treated Poly(dimethyl siloxane) for

    E-print Network

    Quake, Stephen R.

    Biocompatibility and Reduced Drug Absorption of Sol-Gel-Treated Poly(dimethyl siloxane Francisco, California 94143, United States Poly(dimethyl siloxane) (PDMS)-based microfluidic de- vices(dimethyl siloxane) (PDMS) is a popular material for making microfluidic devices. This widespread utility stems from

  15. Properties of PZT Nano-Powder Doped Silica Films Prepared by Sol-Gel Process

    Microsoft Academic Search

    Pei-Chen Yen; Jiann-Shiun Kao; Shang-Yu Huang; Chuen-Horng Tsai; I-Nan Lin

    2002-01-01

    Silica films doped with amorphous PZT nanopowder were prepared by a modified TEOS sol-gel process. The films were annealed by conventional furnace or rapid thermal annealing methods at 700 ¯ respectively, and were examined by field emission scanning electron microscopy and spectro-ellipsometer. Most of the PZT particles were detached from the film after annealing. To avoid this phenomenon, a hydrothermal

  16. Sol-gel deposited electrochromic films for electrochromic smart window glass

    Microsoft Academic Search

    N. Oezer; C. M. Lampert; M. Rubin

    1996-01-01

    Electrochromic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these

  17. The influence of surfactants on the roughness of titania sol-gel films

    SciTech Connect

    Medina-Valtierra, Jorge [Departamento de Ingenieria Quimica y Bioquimica, Instituto Tecnologico de Aguascalientes, Av. A. Lopez Mateos Ote. No. 1801, Fracc. Bona Gens, Aguascalientes 20256 (Mexico)]. E-mail: jormeval@yahoo.com; Frausto-Reyes, Claudio [Centro de Investigaciones en Optica A.C., Loma del Bosque No. 115, Col. Lomas del Campestre, Leon, Gto. 37150 (Mexico)]. E-mail: cfraus@cio.mx; Calixto, Sergio [Centro de Investigaciones en Optica A.C., Loma del Bosque No. 115, Col. Lomas del Campestre, Leon, Gto. 37150 (Mexico)]. E-mail: scalixto@cio.mx; Bosch, Pedro [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, Cd. Universitaria, Mexico, D.F. 04510 (Mexico)]. E-mail: croqcroqcroq@yahoo.com; Hugo Lara, Victor [Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Mexico, D.F. 09340 (Mexico)]. E-mail: lacv@xanum.uam.mx

    2007-03-15

    Substrate dipping in a composite sol-gel solution was used to prepare both smooth and rough thin films of titanium dioxide (TiO{sub 2}) on commercial fiberglass. The deposition of a composite film was done in a beaker using a solution of titanium (IV) isopropoxide as the sol-gel precursor and cetyltrimethyl ammonium bromide as the surfactant. In order to establish a correlation between experimental conditions and the titanium oxide produced, as well as the film quality, the calcined samples were characterized using Raman spectroscopy, UV-vis spectrophotometry, scanning electron microscopy and atomic force microscopy. One of the most important results is that a 61-nm TiO{sub 2} film was obtained with a short immersion of fiberglass into the sol-gel without surfactant. In other cases, the deposited film consisted of a titanium precursor gel encapsulating micelles of surfactant. The gel films were converted to only the anatase phase by calcining them at 500 deg. C. The resulting films were crystalline and exhibited a uniform surface topography. In the present paper, it was found that the TiO{sub 2} films prepared from the sol-gel with a surfactant showed a granular microstructure, and are composed of irregular particles between 1.5 and 3 {mu}m. Smooth TiO{sub 2} films could have useful optical and corrosion-protective properties and, on other hand, roughness on the TiO{sub 2} films can enhance the inherent photocatalytic activity.

  18. Characterization of boria-alumina mixed oxides prepared by a sol-gel method.

    E-print Network

    Boyer, Edmond

    Characterization of boria-alumina mixed oxides prepared by a sol-gel method. Part 2 of alumina matrix are present after calcination of dried B-alumina xerogels with B / Al > 0.15 prepared species (a) Boehmite sheet BO4 species (a) Calcination `Alumina' sheet New BO4 species Dislocation due

  19. Characterization of boria-alumina mixed oxides prepared by a sol-gel method.

    E-print Network

    Paris-Sud XI, Université de

    Characterization of boria-alumina mixed oxides prepared by a sol- gel method. Part 1: NMR induces the creation of tetrahedral alumina species in the boehmite network initially exclusively constituted of octahedral aluminum species. Al O Al Boehmite matrix: Octahedral alumina species arrangement O

  20. Electrochemical investigation of high-performance silane sol–gel films containing clay nanoparticles

    Microsoft Academic Search

    F. Deflorian; S. Rossi; M. Fedel; C. Motte

    2010-01-01

    Silane sol–gel coatings are widely used as adhesion promoters between inorganic substrates, such as metals, and organic coatings. The aim of these pre-treatments is to enhance the corrosion protection performance of the organic coating improving the adhesion to the substrate and acting as a barrier against water and aggressive ions diffusion. It is a matter of fact that the silane

  1. Investigation of optical properties of anthocyanin doped into sol-gel based matrix

    NASA Astrophysics Data System (ADS)

    Hashim, Hasrina; Abdul Aziz, Nik Mohd Azmi Nik; Isnin, Aishah

    2012-06-01

    Anthocyanin dye was extracted from petal of Hibiscus rosasinensis (Bunga Raya) and doped into sol-gel based matrix to investigate an effect of pH change on its optical properties. Sol-gel matrix based on Vinyl triethoxysilene (VTES) as a precursor was prepared through Sol-gel process at pH 7. The sol was doped with 0.1% of Anthocyanin and the same amount of dye was also dissolved in ethanol as a comparative sample. Hydrochloric Acid, HCl and Tetramethylammonium Hydroxide, TMAH were used to change the pH value by adding them at various concentrations into each sample. The emission spectra and chemical structures of the samples were measured by Spectrofluorometer and Fourier Transform Infrared (FTIR) respectively. When excited at 410 nm, two emission peaks at about 492 and 574 nm were observed for Anthocyanin in acidic environment both in ethanol and VTES sol. In base environment however, only Anthocyanin dissolved in ethanol produced emission peak with a single peak at about 539 nm. The sensitivity of Anthocyanin dye toward pH changes in VTES open a possibility to use it as sensing element in which sol-gel based matrix are known to have higher mechanical strength and thermal stability.

  2. Pressureless sintering of sol-gel derived alumina–zirconia composites

    Microsoft Academic Search

    Doni Jayaseelan; Tadahiro Nishikawa; Hideo Awaji; F. D Gnanam

    1998-01-01

    Alumina–zirconia (pure zirconia, 12 mol % ceria stabilized zirconia and 3 mol% yttria stabilized zirconia) composites containing 5, 10, 15, 20 and 25 vol.% zirconia were prepared by sol-gel technique. The procedure involved the following steps: preparation of stable (hydrous) alumina and zirconia sols, mixing of sols in proper ratio, to obtain the final precursor with the desired composition and

  3. Synthesis and Characterization of Pure and Doped Ceria Films by Sol-gel and Sputtering

    Microsoft Academic Search

    Kurt T. Koch; Laxmikant V. Saraf

    2004-01-01

    Synthesis and Characterization of Pure and Doped Ceria Films by Sol-gel and Sputtering. KURT T. KOCH (University of Missouri, Rolla, MO, 65409) LAXMIKANT SARAF (Environmental and Molecular Science Laboratory (Part of Pacific Northwest National Laboratory), Richland, Washington 99352). Pure and doped Ceria are known for their ability to gain or lose Oxygen, which is of interest to the Solid Oxide

  4. The sol-gel preparation of single and mixed oxides from commercial preformed sols

    Microsoft Academic Search

    Steven John Monaco

    1998-01-01

    The sol-gel preparation of single and mixed oxide materials has been researched extensively in recent years. These studies commonly use metal alkoxides as precursors due to their high purity and generally well understood chemistry. However, as a class of materials they are expensive, very reactive, and moisture sensitive, factors that all hinder their employment in a large-scale industrial process. The

  5. A composite sol–gel\\/fluoropolymer matrix for dissolved oxygen optical sensing

    Microsoft Academic Search

    R. N. Gillanders; M. C. Tedford; P. J. Crilly; R. T. Bailey

    2004-01-01

    A thin film dissolved oxygen optical sensor was fabricated by encapsulating the phosphorescent dye erythrosin B in a sol–gel\\/fluoropolymer composite matrix. Strong phosphorescence, which was efficiently quenched by dissolved oxygen, was observed. The sensor was stable, optically transparent, resistant to contamination, with good mechanical properties. Fast response, coupled with good sensitivity and resistance to leaching, were also exhibited by this

  6. Improving the temperature performance of low-density ceramic heatshields through sol-gel processing

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Leiser, Daniel; Sommers, Jeneen; Esfahani, Lili

    1991-01-01

    The performance of rigid insulations for use as thermal protection materials on reentry vehicles can be characterized by their resistance to dimensional and morphological change when exposed to an isothermal environment equivalent to that generated in entry. Improvements in these material characteristics for alumina-enhanced thermal barrier insulation by compositional modification through sol-gel processing are reported.

  7. Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol–gel combustion method

    Microsoft Academic Search

    Yingchao Han; Shipu Li; Xinyu Wang; Xiaoming Chen

    2004-01-01

    The citric acid sol–gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous

  8. Enhanced Proteolytic Activity of Covalently Bound Enzymes in Photopolymerized Sol Gel

    E-print Network

    Zare, Richard N.

    Enhanced Proteolytic Activity of Covalently Bound Enzymes in Photopolymerized Sol Gel Maria T (BAEE) and two peptides, neuro- tensin and insulin chain B. The coupling of the enzyme to the monolith on the carboxyl side of methionine residues whereas the enzyme trypsin specifically hydrolyzes peptide bonds

  9. Enzyme Stabilization by Covalent Binding in Nanoporous Sol-Gel Glass for

    E-print Network

    Wang, Ping

    Enzyme Stabilization by Covalent Binding in Nanoporous Sol-Gel Glass for Nonaqueous Biocatalysis mate- rial for enzyme immobilization. A model enzyme, -chy- motrypsin, was efficiently bound onto the glass via a bifunctional ligand, trimethoxysilylpropanal, with an ac- tive enzyme loading of 0.54 wt

  10. Preparation of Water-Repellent Glass by Sol–Gel Process Using Perfluoroalkylsilane and Tetraethoxysilane

    Microsoft Academic Search

    Hye-Jeong Jeong; Dong-Kwon Kim; Soo-Bok Lee; Soo-Han Kwon; Kohei Kadono

    2001-01-01

    Coating films on glass substrate were prepared by sol–gel process using alkoxide solutions containing perfluoroalkylsilane (PFAS) and tetraethoxysilane (TEOS). The physical properties of the coating films were characterized by SEM, FT-IR, and XRD. And their surface properties were investigated by measuring contact angles and atomic compositions. Transparent coating films with smooth surface and uniform thickness could be obtained. The contact

  11. Sol–gel derived carrier for the controlled release of proteins

    Microsoft Academic Search

    Erick M Santos; Shulamith Radin; Paul Ducheyne

    1999-01-01

    Sol–gel derived porous silica carriers for the controlled release of proteins were synthesized using a room temperature process. The materials are intended to serve as both substrates for bone growth as well as to allow incorporated proteins such as growth factors to diffuse out and stimulate cell function and tissue healing. The data document that the in vitro release of

  12. HIGH PURITY FERROELECTRIC MATERIALS BY SOL-GEL PROCESS FOR MICROWAVE APPLICATIONS

    E-print Network

    De Flaviis, Franco

    TUID-8 HIGH PURITY FERROELECTRIC MATERIALS BY SOL-GEL PROCESS FOR MICROWAVE APPLICATIONS Franco De, Department of Electrical Engineering ABSTRACT Ferroelectric materials (FEM) have a dielectric constant which thin film and thin ceramics of BaTi03(BTO), BaxSrl.xTi03 (BST) and PbTi03 (PTO) is presented. The high

  13. Synthesis of Nano Silica Particles for Polishing Prepared by Sol–Gel Method

    Microsoft Academic Search

    Yasuhiko Arai; Hiroyo Segawa; Kazuaki Yoshida

    2004-01-01

    In order to produce an excellent abrasive, a fabrication method for cocoon shaped silica particles has been studied. The particles are prepared from TMOS, water, ammonia and methanol by a sol–gel method. The method is to add the methanol solution of TMOS at a constant supply rate to a mixture of water, ammonia and methanol. Effects of various reaction conditions

  14. Carbon nanotube silica glass composites in thin films by the sol–gel technique

    Microsoft Academic Search

    L. Berguiga; J. Bellessa; F. Vocanson; E. Bernstein; J. C. Plenet

    2006-01-01

    We report the fabrication of a carbon nanotube silica composite. This inorganic composite is produced with the sol–gel technique and deposited in thin films by the dip-coating method. The functionalization of multiwall carbon nanotubes is a decisive step in order to introduce them inside a silica matrix. Functionalization ensures good homogeneity of multiwall carbon nanotubes. Atomic force microscopy and surface

  15. Titanium dioxide nanocrystalline bactericidal thin films grown by sol-gel technique

    Microsoft Academic Search

    Fernando Gordillo Delgado; Katherine Villa Gómez; Claudia Mejía Morales

    2008-01-01

    Titanium dioxide thin films were grown by sol–gel technique in order to obtain films to be used in photocatalytic reactions. We present results on the structural and optical characterization measured for series of films in which number of layers and sintering temperature were changed. Using X-ray diffraction we have characterized the crystalline phase in the films depending on the growth

  16. Enhancement of evanescent fluorescence from fiber optic sensors by thin film sol gel coatings

    Microsoft Academic Search

    H. P. Kao; N. Yang; J. S. Schoeniger

    1997-01-01

    A theoretical analysis and experimental demonstration of the increase in collected evanescent fluorescence for a fiber optic sensor having a high refractive index, titanium sol gel, thin film coating is presented. Collected fluorescence increased by up to 6 X over that from a bare fiber having a numerical aperture of 0.60. The maximum collected fluorescence increased and shifted to smaller

  17. Ferroelectric-Like Properties of Amorphous Metal Oxide Thin Films Prepared by Sol-Gel Technique

    Microsoft Academic Search

    Yuhuan Xu

    1995-01-01

    Advances in the field of both optical and electrical integrated circuit devices require new thin film materials. Ferroelectric materials have attractive properties such as hysteresis behavior, pyroelectricity, piezoelectricity and nonlinear optical properties. Many ferroelectric thin films have been successfully prepared from metal organic compounds via sol-gel processing. Thus far, research has concentrated upon polycrystalline or epitaxial ferroelectric films. For amorphous

  18. Stereoselective histidine sensor based on molecularly imprinted sol-gel films.

    PubMed

    Zhang, Zhaohui; Liao, Haiping; Li, Hui; Nie, Lihua; Yao, Shouzhuo

    2005-01-01

    A piezoelectric sensor coated with a thin molecularly imprinted sol-gel film has been developed for the determination of L-histidine in the liquid phase. Without preprotection, L-histidine was imprinted directly into silica sol-gel films that consisted of a hybrid mixture of functionalized organosilicon precursors (phenyltrimethoxysilane and methyltrimethoxysolane). The viscoelasticity of the film in the air and in buffer solution has been studied by the piezoelectric quartz crystal impedance technique. The binding of L-histidine to the imprinted film in the liquid phase was investigated by the piezoelectric microgravimetry and electrochemical impedance technique. Scatchard analysis showed that the maximum binding site (Qmax) of the L-histidine imprinted sol-gel film is about 23.7 micromol/g. A linear range from 5.0x10(-8) to 1.0x10(-4) M for a detection of L-histidine has been observed with a detection limit of 2.5x10(-8) M for S/N=3. The proposed imprinted sol-gel sensor exhibits good stability, high specificity, and excellent stereoselectivity. PMID:15582565

  19. Optical characterization of anti reflective sol-gel coatings fabricated using dip coating method

    NASA Astrophysics Data System (ADS)

    Melninkaitis, A.; Juškevi?ius, K.; Maciulevi?ius, M.; Sirutkaitis, V.; Beganskien?, A.; Kazadojev, I.; Kareiva, A.; Perednis, D.

    2007-01-01

    In recent years, there has been a growing interest in further development of sol-gel method which can produce ceramics and glasses using chemical precursors at relative low-temperatures. The applications for sol-gel derived products are numerous. Department of General and Inorganic Chemistry with Laser Research Center of Vilnius University and Institute of Physics continues an ongoing research effort on the synthesis, deposition and characterization of porous solgel. Our target is highly optically resistant anti-reflective (AR) coatings for general optics and nonlinear optical crystals. In order to produce AR coatings a silica (SiO II) sol-gel has been dip coated on the set of fused silica substrates. The optical properties and structure of AR-coatings deposited from hydrolysed tetraethylorthosilicate (TEOS) sol were characterized in detail in this study. The influence of different parameters on the formation of colloidal silica antireflective coatings by dip-coating technique has been investigated. All samples were characterized performing, transmission electron microscopy, UV-visible spectroscopy, atomic force microscopy, ellipsometric, total scattering and laser-induced damage threshold measurements. Herewith we present our recent results on synthesis of sol-gel solvents, coating fabrication and characterization of their optical properties.

  20. Fabrication and characterization of thin, spin-coated, sol-gel, and colloidal silica films

    Microsoft Academic Search

    David L. Williams; Sven G. Roden; Terence A. King; Kevin R. Welford

    1994-01-01

    This study was conducted on both inorganic silica and organically modified silica (ormosil) films. Sol-gel derived silica films were prepared by spin-coating either a sol or a colloidal silica (COLSI) suspension mixed with a polysiloxane solution onto glass substrates. The films were microscopically investigated to reveal their structure. The optical quality of the films was measured using a scatterometer which

  1. Non-cytotoxic antibacterial silver-coumarin complex doped sol-gel coatings.

    PubMed

    Jaiswal, Swarna; Bhattacharya, Kunal; Sullivan, Maeve; Walsh, Maureen; Creaven, Bernadette S; Laffir, Fathima; Duffy, Brendan; McHale, Patrick

    2013-02-01

    Microbial colonisation on clinical and industrial surfaces is currently of global concern and silane based sol-gel coatings are being proposed as potential solutions. Sol-gels are chemically inert, stable and homogeneous and can be designed to act as a reservoir for releasing antimicrobial agents over extended time periods. In the present study, silver nitrate (AgN) and a series of silver coumarin complexes based on coumarin-3-carboxylatosilver (AgC) and it is 6, 7 and 8 hydroxylated analogues (Ag6, Ag7, Ag8) were incorporated into sol-gel coatings. The comparative antibacterial activity of the coatings was determined against meticillin resistant Staphylococcus aureus (MRSA) and multidrug resistance Enterobacter cloacae WT6. The percentage growth inhibitions were found in the range of 9.2 (±2.7)-66.0 (±1.2)% at low silver loadings of 0.3% (w/w) with E. cloacae being the more susceptible. Results showed that among the Ag coumarin complexes, the Ag8 doped coating had the highest antibiofilm property. XPS confirmed the presence of silver in the nanoparticulate state (Ag(0)) at the coating surface where it remained after 4 days of exposure to bacterial culture. Comparative cytotoxicity studies revealed that the Ag-complex coatings were less toxic than the AgN coating. Thus, it can be concluded that a sol-gel matrix with Ag-coumarin complexes may provide non-toxic surfaces with antibacterial properties. PMID:23010125

  2. Sol–gel synthesis and controlled sintering of silver vanadium oxide

    Microsoft Academic Search

    Esther S. Takeuchi; Amy C. Marschilok; Randolph A. Leising; Kenneth J. Takeuchi

    2007-01-01

    A two part synthesis process is used to prepare pure silver vanadium oxide (SVO) with desired properties. First, a low temperature sol gel process is used to generate SVO feedstock materials. These materials can then the sintered using varied time and temperature profiles to generate SVO with desired physical characteristics.

  3. Processing and optical properties of sol-gel derived nanostructured CdWO4 films

    Microsoft Academic Search

    H. M. Shang; Y. Wang; M. Bliss; G. Z. Cao

    2005-01-01

    Dense and transparent cadmium tungstate (CWO) scintillation films have been first synthesized by sol-gel processing and their optical properties have been studied. Different precursors (tungsten oxychloride and tungstic acid), solvents (alcohol based and aqueous based) and thermal annealing processing conditions were investigated to achieve stable sols and resultant dense nanocrystalline CWO films. XRD showed CWO was the only detectable crystalline

  4. Sol-gel deposition of buffer layers on biaxially textured metal substances

    DOEpatents

    Shoup, Shara S. (Woodstock, GA); Paranthamam, Mariappan (Knoxville, TN); Beach, David B. (Knoxville, TN); Kroeger, Donald M. (Knoxville, TN); Goyal, Amit (Knoxville, TN)

    2000-01-01

    A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

  5. DOI: 10.1002/cplu.201200088 Biofilm Formation on Chromatic SolGel/Polydiacetylene

    E-print Network

    Jelinek, Raz

    DOI: 10.1002/cplu.201200088 Biofilm Formation on Chromatic Sol­Gel/Polydiacetylene Films Margarita] Introduction Bacterial biofilms are integrated communities of cells consist- ing of one or more species joined to the ecology and biology of most bacterial strains. Owing to the impregnable nature of biofilm frameworks

  6. Immobilization of Biomolecules in Sol–Gels: Biological and Analytical Applications

    Microsoft Academic Search

    Vivek Babu Kandimalla; Vijay Shyam Tripathi; Huangxian Ju

    2006-01-01

    The encapsulation or generation of new surfaces that can fix biomolecules firmly without altering their original conformations and activities is still challenging for the utilization of biochemical functions of active biomolecules. Presently, sol–gel chemistry offers new and interesting possibilities for the promising encapsulation of heat-sensitive and fragile biomolecules (enzyme, protein, antibody and whole cells of plant, animal and microbes); mainly,

  7. Development of sol-gel integrated optical waveguide for Electro-Optical PCB

    Microsoft Academic Search

    Michal Siesicki; Krzysztof Nieweglowski; Klaus-Jürgen Wolter; Sergiusz Patela

    2008-01-01

    For several years data rate limitation in printed circuit technology becomes more and more actually. A promising approach to increase bandwidth in the future links are integrated optical interconnections. The next generation PCBs will be Electro-Optical Printed Circuit Board (EOPCB). Polymer optical waveguides on the basis of cost effective sol-gel materials are one possible solution to be up to data

  8. Preparation and electrochemical study of cerium–silica sol–gel thin films

    Microsoft Academic Search

    M. Garcia-Heras; A. Jimenez-Morales; B. Casal; J. C. Galvan; S. Radzki; M. A. Villegas

    2004-01-01

    Design and development of suitable multilayered systems for delaying corrosion advance in metals requires that both the alteration mechanisms of the metal and the behaviour and properties of the protective coatings be known. Coatings prepared by the sol–gel method provide a good approach as protective layers on metallic surfaces. This kind of coatings can be prepared from pure chemical reagents

  9. Integrated ultrasonic transducers made by the sol–gel spray technique for structural health monitoring

    Microsoft Academic Search

    M Kobayashi; C-K Jen; J-F Moisan; N Mrad; S B Nguyen

    2007-01-01

    Integrated piezoelectric-based ultrasonic transducers (UTs) have been developed for potential structural health monitoring. Fabrication techniques and performance evaluation of these transducers at selected monitoring sites are presented. Our novel transducer fabrication approach focuses on the use of handheld and readily accessible equipment to perform sol–gel spray coating, including the use of a heat gun or a torch, to carry out

  10. Integrated ultrasonic transducers made by the sol gel spray technique for structural health monitoring

    Microsoft Academic Search

    M. Kobayashi; C.-K. Jen; J.-F. Moisan; N. Mrad; S. B. Nguyen

    2007-01-01

    Integrated piezoelectric-based ultrasonic transducers (UTs) have been developed for potential structural health monitoring. Fabrication techniques and performance evaluation of these transducers at selected monitoring sites are presented. Our novel transducer fabrication approach focuses on the use of handheld and readily accessible equipment to perform sol-gel spray coating, including the use of a heat gun or a torch, to carry out

  11. OPTIMIZATION OF ALKYL ESTER PRODUCTION FROM GREASE USING A PHYLLOSILICATE SOL-GEL IMMOBILIZED LIPASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simple alkyl ester derivatives of restaurant grease were prepared using a lipase from Pseudomonas cepacia immobilized within a phyllosilicate sol-gel matrix as biocatalyst. Alcoholysis reactions of grease were carried out in solvent-free media using a one step addition of alcohol to reaction mixtur...

  12. Osteoblast adhesion and matrix mineralization on sol-gel-derived titanium oxide.

    PubMed

    Advincula, Maria C; Rahemtulla, Firoz G; Advincula, Rigoberto C; Ada, Earl T; Lemons, Jack E; Bellis, Susan L

    2006-04-01

    The biological events occurring at the bone-implant interface are influenced by the topography, chemistry and wettability of the implant surface. The surface properties of titanium alloy prepared by either surface sol-gel processing (SSP), or by passivation with nitric acid, were investigated systematically using X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and contact angle metrology. The bioreactivity of the substrates was assessed by evaluating MC3T3-E1 osteoblastic cell adhesion, as well as by in vitro formation of mineralized matrix. Surface analysis of sol-gel-derived oxide on Ti6Al4V substrates showed a predominantly titanium dioxide (TiO(2)) composition with abundant hydroxyl groups. The surface was highly wettable, rougher and more porous compared to that of the passivated substrate. Significantly more cells adhered to the sol-gel-coated surface, as compared with passivated surfaces, at 1 and 24h following cell seeding, and a markedly greater number of mineralized nodules were observed on sol-gel coatings. Collectively our results show that the surface properties of titanium alloy can be modified by SSP to enhance the bioreactivity of this biomaterial. PMID:16313951

  13. Submicron metal oxide structures by a sol-gel process on patterned substrates

    Microsoft Academic Search

    Clemens Bechinger; Hans Muffler; Claudia Schäfle; Olle Sundberg; Paul Leiderer

    2000-01-01

    We report about a combination of micro-contact-printing and the sol-gel technique which results in structures in the micron- and submicron range. This technique which is here demonstrated on electrochromic tungsten oxide does not rely on vacuum methods and may therefore be easily upscaled to large areas.

  14. Sol-gel composite hydrothermal processing of barium strontium titanate films for microwave frequency applications

    NASA Astrophysics Data System (ADS)

    Zelonka, Kim

    Stoichiometric barium strontium titanate (BST) films of composition Ba 0.7Sr0.3TiO3 with thickness >2mum have been fabricated on various substrates including Si/SiO2/Pt and Al 2O3/Au by hydrothermal sol-gel composite processing. This film deposition technique involves the treatment of a spun-on sol-gel composite film in an alkaline aqueous solution at temperatures from 50-200°C and pressures of 1-15 atm. An initial hydrolysis procedure eliminates dissolution of the dried sol-gel prior to hydrothermal processing. Glancing angle x-ray diffraction shows excellent crystallinity and stoichiometry in the BST films. Scanning electron micrography, atomic force microscopy, and transmission electron microscopy are used to examine the microstructure of the films. Both the film morphology and electrical studies suggest that the microstructure of the films evolves by nucleation and growth of the sol-gel-derived BST on the underlying powder, resulting in an interconnected microstructure in which the sol-gel-derived material forms bridges between the original powder particles. The relative dielectric constant and loss tangent of the BST films are measured in the frequency range from 1 to 100 kHz using parallel plate capacitors. Changes in the electrical characteristics of the film upon variation of hydrothermal process parameters including temperature, process duration, and the concentration of the hydrothermal solution are examined. At 100 kHz relative permittivities of the films range from epsilonr = 400-1200 and loss tangents lie in the range 0.05 < tan delta < 0.10, depending on the parameters of preparation. Complex impedance analysis is used to examine the varying bulk and grain boundary contributions to the total film behaviour. BST pellets of various thicknesses have also been produced. These pellets are impregnated with BST sol-gel which is subsequently hydrothermally processed. The electrical characteristics of the pellets are evaluated and explained in terms of the degree of penetration of the sol-gel into the pellets. The relative dielectric constant and loss tangent of the films between 5 and 40 GHz are determined using a set of coplanar waveguides with spur-line filters. The maximum relative dielectric permittivity at 40 GHz was found to be 94. The loss tangent of the film was found to increase from 3.5% to 6.0% from 10-15 GHz. The permittivity of the films from 1 kHz to 40 GHz is explained in terms of a fractal description of the film microstructure.

  15. Conformal sol-gel coatings on three-dimensional nanostructured templates

    NASA Astrophysics Data System (ADS)

    Weatherspoon, Michael R.

    Sol-gel processing techniques, such as spin coating and dip coating, have successfully been utilized over the past several decades to apply conformal coatings on planar substrates; however, controlled film growth on three-dimensional (3-D) nanostructured templates using the sol-gel process remains a significant challenge. Obstacles such as, uncontrolled hydrolyzation and condensation of metal alkoxide precursors on nanostructured surfaces are a few of the obstacles which lead to coatings with undesirable thicknesses and excess inorganic particles. A little over a decade ago, a surface sol-gel process was developed which utilizes stepwise film growth of anhydrous metal alkoxide precursors with hydroxylated surfaces. The surface sol-gel process provides control over the applied coating thickness and is viewed as a wet chemical analog to atomic layer deposition (ALD). The work presented in this dissertation has focused on applying conformal sol-gel derived coatings with controlled thicknesses on 3-D nanostructured templates. The templates utilized in this work were derived from biological species, such as diatoms and butterflies, as well as a synthetic photoresist polymer (SU-8). Coatings were applied on the templates using a conventional reflux/evaporation deposition process and a custom-built computer controlled surface sol-gel pumping system. The coatings applied using the reflux/evaporation process yielded conformal coatings with uncontrolled film thicknesses whereas the coatings applied using the surface sol-gel process yielded conformal coatings with controlled thicknesses. Barium titanate and europium-doped barium titanate coatings were applied on diatom frustules using the reflux/evaporation deposition process. The silica-based diatom frustules had to first be converted into magnesia/silicon composite replicas using a gas/solid displacement reaction to render the template chemically compatible with the barium titanate-based coating. Conformal titanate-based coatings were obtained on the magnesia frustule replicas possessing uncontrolled thicknesses and excess inorganic particles using the reflux/evaporation deposition process. The europium-doped barium titanate coated frustules exhibited bright red photoluminescent properties upon stimulation with an ultraviolet light source. Silica-based diatom frustules were also utilized as 3-D nanostructured templates for fabrication of a micro-scale nitric oxide gas sensor. Tin oxide coatings were applied on the silica frustules using the automated surface sol-gel pumping system. An organic dendrimer method was developed for amplifying hydroxyl groups on the silica frustule surfaces to enhance the surface sol-gel deposition process. Conformal coatings with controlled thicknesses were obtained on the hydroxyl amplified frustule surfaces; however, little if any deposition was observed on the frustules that were not subjected to the hydroxyl amplification process. A single tin oxide coated diatom frustule served as a gas sensor component which was sensitive to very low concentrations of nitric oxide gas. The automated surface sol-gel system was also used to apply multicomponent tin oxide-doped titania alkoxide chemistries on the wing scales of a blue Morpho butterfly. The alkoxide solutions reacted directly with the OH functionalities provided by the native chitin chemistry of the scales. The tin oxide served as a rutile nucleating agent which allowed the titania to completely crystallize in the high refractive index rutile titania phase with doping concentrations of tin oxide as low as 7 mol% after annealing at 450°C. The tin oxide-doped titania coatings were both nanocrystalline and nanothick and replicated the nanostructured scales with a high degree of accuracy. Undoped titania coatings applied on the scales required a heat treatment of 900°C to crystallize the coating in the rutile titania phase which led to adverse coarsening effects which destroyed the nanostructed features of the scales. Tin oxide-doped titania coatings were also deposited on synthetic polymer (SU-8) pho

  16. Magnetic resonance as a structural probe of a uranium (VI) sol-gel process

    SciTech Connect

    King, C.M.; Thompson, M.C.; Buchanan, B.R. [Westinghouse Savannah River Co., Aiken, SC (United States); King, R.B. [Georgia Univ., Athens, GA (United States). Dept. of Chemistry; Garber, A.R. [South Carolina Univ., Columbia, SC (United States). Dept. of Chemistry

    1989-12-31

    NMR investigations on the ORNL process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub l2}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-Gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sub 17}0 NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}]{sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results show that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an ``intercalation`` cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ ion exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2}[(UO{sub 2}){sub 8}O{sub 4}(OH){sub 10}] {center_dot} 8H{sub 2}0. This compound is the precursor to sintered U0{sub 2} ceramic fuel.

  17. Magnetic resonance as a structural probe of a uranium (VI) sol-gel process

    SciTech Connect

    King, C.M.; Thompson, M.C.; Buchanan, B.R. (Westinghouse Savannah River Co., Aiken, SC (United States)); King, R.B. (Georgia Univ., Athens, GA (United States). Dept. of Chemistry); Garber, A.R. (South Carolina Univ., Columbia, SC (United States). Dept. of Chemistry)

    1989-01-01

    NMR investigations on the ORNL process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub l2}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-Gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sub 17}0 NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, ((UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}){sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results show that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an intercalation'' cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ ion exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2}((UO{sub 2}){sub 8}O{sub 4}(OH){sub 10}) {center dot} 8H{sub 2}0. This compound is the precursor to sintered U0{sub 2} ceramic fuel.

  18. Nonlinear solid-state filter based on photochromism induced by 2-photon absorption in a dye-doped sol-gel

    NASA Astrophysics Data System (ADS)

    Gvishi, Raz; Zhao, Peng; Hu, Honghua; Strum, Galit; Tal, Amir; Grinvald, Shmuel; Bar, Galit; Bekere, Laura; Lokshin, Vladimir; Khodorkovsky, Vladimir; Sigalov, Mark; Hagan, David; Van Stryland, Eric

    2014-10-01

    There is much interest in enhancement of the absorbance performance of nonlinear absorber solid-state filters. In this work we present an advanced reversible nonlinear filter based on a dye-doped sol-gel matrix. The absorbance enhancement was achieved by using a combination of two absorption mechanisms in the same molecule; a photochromic absorption which is induced by 2-photon absorption (2PA). The 2PA serves as the trigger for initiating the photochromism through Förster-resonance-energy-transfer (FRET) between the fluorescent donor and the photochromic acceptor. We synthesized a new bifunctional-chromophore that incorporated a carbazole-derived 2PA fluorescent donor and a chromene-derived photochromic acceptor, covalently linked together in a single molecule by a ~6 Å carboxyl group or oxygen bridge. The bifunctional-chromophore was doped in an inorganic-organic hybrid matrix prepared by the fast-sol-gel process. These materials solidify without shrinkage or formation of cracks and present promising properties as optical matrices for smart filters. The dye-doped sol-gel disc presents high transparency in the visible region ("colorless"), which under UV-irradiation (one-photon absorption in the photochromic part of the molecule), transforms into a strongly absorbing filter ("dark colored"), due to the conversion of the photochromic moiety to its "open" absorbing form. We have demonstrated that this ring-opening can also be induced by visible-light (620 nm) using the 2PA carbazole-derived moiety of the molecule. We have studied the fabrication routes and optical performance of these filters. We present studies of the 2PA mechanism of the carbazole derivative, FRET efficiency of the combined-molecule as well as in solutions of the individual moieties, and reversible dynamics of the photochromic moiety.

  19. Phthalic acid assisted nano-sized spinel LiMnO and LiCrMn{sub 2-x}O (x = 0.00-0.40) via sol-gel synthesis and its electrochemical behaviour for use in Li-ion-batteries

    Microsoft Academic Search

    R. Thirunakaran; A. Sivashanmugam; S. Gopukumar; Charles W. Dunnill; Duncan H. Gregory

    2008-01-01

    Nano-sized particles of spinel LiMnO and LiCrMn{sub 2-x}O (x = Cr; 0.00-0.40) have been synthesized using phthalic acid as chelating agent for the first time by sol-gel method. When compared to solid-state synthesis method, the sol-gel route reduces heating time of synthesize and to obtain particles of uniform surface morphology. The synthesized samples were characterized through thermo-gravimetric analysis (TGA), X-ray

  20. Phthalic acid assisted nano-sized spinel LiMn 2O 4 and LiCr x Mn 2? x O 4 ( x = 0.00–0.40) via sol–gel synthesis and its electrochemical behaviour for use in Li-ion-batteries

    Microsoft Academic Search

    R. Thirunakaran; A. Sivashanmugam; S. Gopukumar; Charles W. Dunnill; Duncan H. Gregory

    2008-01-01

    Nano-sized particles of spinel LiMn2O4 and LiCrxMn2?xO4 (x=Cr; 0.00–0.40) have been synthesized using phthalic acid as chelating agent for the first time by sol–gel method. When compared to solid-state synthesis method, the sol–gel route reduces heating time of synthesize and to obtain particles of uniform surface morphology. The synthesized samples were characterized through thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), scanning

  1. Sol-gel synthesis of nanocomposite materials based on lithium niobate nanocrystals dispersed in a silica glass matrix

    SciTech Connect

    Marenna, Elisa [Dipartimento di Ingegneria dei Materiali e della Produzione, Universita di Napoli Federico II, Piazzale V. Tecchio, 80125 Napoli (Italy); Aruta, Carmela [CNR-INFM Coherentia e Dipartimento di Fisica, Universita di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli (Italy); Fanelli, Esther [Dipartimento di Ingegneria dei Materiali e della Produzione, Universita di Napoli Federico II, Piazzale V. Tecchio, 80125 Napoli (Italy); Barra, Mario [CNR-INFM Coherentia e Dipartimento di Fisica, Universita di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli (Italy); Pernice, Pasquale [Dipartimento di Ingegneria dei Materiali e della Produzione, Universita di Napoli Federico II, Piazzale V. Tecchio, 80125 Napoli (Italy); Aronne, Antonio, E-mail: anaronne@unina.i [Dipartimento di Ingegneria dei Materiali e della Produzione, Universita di Napoli Federico II, Piazzale V. Tecchio, 80125 Napoli (Italy)

    2009-05-15

    With the final goal to obtain thin films containing stoichiometric lithium niobate nanocrystals embedded in an amorphous silica matrix, the synthesis strategy used to set a new inexpensive sol-gel route to prepare nanocomposite materials in the Li{sub 2}O-Nb{sub 2}O{sub 5}-SiO{sub 2} system is reported. In this route, LiNO{sub 3}, NbCl{sub 5} and Si(OC{sub 2}H{sub 5}){sub 4} were used as starting materials. The gels were annealed at different temperatures and nanocrystals of several phases were formed. Futhermore, by controlling the gel compositions and the synthesis parameters, it was possible to obtain LiNbO{sub 3} as only crystallizing phase. LiNbO{sub 3}-SiO{sub 2} nanocomposite thin films on Si-SiO{sub 2} and Al{sub 2}O{sub 3} substrates were grown. The LiNbO{sub 3} average size, increasing with the annealing temperature, was 27 nm for a film of composition 10Li{sub 2}O-10Nb{sub 2}O{sub 5}-80SiO{sub 2} heated 2 h at 800 deg. C. Electrical investigation revealed that the nanocrystals size strongly affects the film conductivity and the occurrence of hysteretic current-voltage curves. - Graphical abstract: Sol-gel synthesis of nanocomposite materials in the Li{sub 2}O-Nb{sub 2}O{sub 5}-SiO{sub 2} system is reported. The goal was to synthesize thin films containing lithium niobate nanocrystals embedded in a silica matrix. Starting from LiNO{sub 3}, NbCl{sub 5} and Si(OC{sub 2}H{sub 5}){sub 4,} it was possible to obtain LiNbO{sub 3} as only crystallizing phase, nanocrystals size was 27 nm for a film 10Li{sub 2}O-10Nb{sub 2}O{sub 5}-80SiO{sub 2} heated 2 h at 800 deg. C.

  2. Effect of sol-gel modifications on formation and morphology of nanocrystalline lanthanum aluminate

    SciTech Connect

    Koc, S. Naci [Department of Chemical Engineering, Istanbul University, Istanbul (Turkey)]. E-mail: nacik@istanbul.edu.tr; Oksuzomer, Faruk [Department of Chemical Engineering, Istanbul University, Istanbul (Turkey); Yasar, Erdem [Department of Physics, Kirikkale University, Kirikkale (Turkey); Akturk, Selcuk [Department of Physics, Kirikkale University, Kirikkale (Turkey); Gurkaynak, M. Ali [Department of Chemical Engineering, Istanbul University, Istanbul (Turkey)

    2006-12-14

    LaAlO{sub 3} powders are prepared by sol-gel method. The effect of preparation conditions on morphological properties and crystal formations are investigated. iso-Propanol/tert-butanol and ethyl acetoacetate/ethylene glycol monomethylether are used solvents and complexing agents, respectively. Samples are dried with conventional and freeze-drying methods and calcined between 600 and 1000 deg. C. TGA, DTA, XRD, SEM and TEM methods are used for characterization. It is observed that freeze-dried sample prepared with tert-butanol has the lowest LaAlO{sub 3} formation temperature and uniform rhombohedral crystals. But conventionally dried sample, prepared with iso-propanol has smallest agglomerates at 1000 deg. C and does not show clear crystallization temperature in DTA analysis. The XRD peaks of LaAlO{sub 3} crystal are observed at 600 deg. C for all samples prepared by various sol-gel conditions.

  3. Synthesis and characterization of a photochromic sol gel material functionalized with azo dye

    NASA Astrophysics Data System (ADS)

    Ke, Xianjun; Yan, Xingzhong; Song, Sangyup; Li, Daqun; Yang, Jame J.; Wang, Michael R.

    2007-07-01

    An azo dye functionalized sol-gel material has been designed and synthesized to possess photochromism under a green laser beam illumination control. 10-mW laser illumination with a spot size of 1 mm2 at 532 nm wavelength on the film material was found to result in 6 × 10-4 change in material refractive index. The response time of the material photochromism is around 50 ms (3-dB modulation bandwidth of 20 Hz). Further optical transmission measurements reveal low optical absorption by the film material at 1.55 ?m wavelength window. The investigation of a tunable waveguide Bragg grating device with the sol-gel material suggests a new promising platform candidate for the fabrication of all-optical controlled photonic devices.

  4. Transversely tapered hybrid electro-optic polymer/sol-gel Mach-Zehnder waveguide modulators

    NASA Astrophysics Data System (ADS)

    Enami, Y.; Mathine, D.; DeRose, C. T.; Norwood, R. A.; Luo, J.; Jen, A. K.-Y.; Peyghambarian, N.

    2008-05-01

    We show results of a proposed hybrid modulator structure that reduces both the optical loss and half wave voltage (V?). A sol-gel waveguide core transversely sandwiched between two Mach-Zehnder arms of electro-optic (EO) polymer cores enables an adiabatic transverse transition between the sol-gel and the EO polymer cores without the need for Y branches. The undercladding thickness is reduced to 3.7?m with negligible further optical loss from the bottom electrode. EO modulation with V? of 1.8V at 1550nm is demonstrated using a guest-host EO polymer, with an optical insertion loss of 13.7dB in the transverse magnetic mode.

  5. Relaxation dynamics near the sol-gel transition: From cluster approach to mode-coupling theory

    NASA Astrophysics Data System (ADS)

    Coniglio, A.; Arenzon, J. J.; Fierro, A.; Sellitto, M.

    2014-10-01

    A long standing problem in glassy dynamics is the geometrical interpretation of clusters and the role they play in the observed scaling laws. In this context, the mode-coupling theory (MCT) of type-A transition and the sol-gel transition are both characterized by a structural arrest to a disordered state in which the long-time limit of the correlator continuously approaches zero at the transition point. In this paper, we describe a cluster approach to the sol-gel transition and explore its predictions, including universal scaling laws and a new stretched relaxation regime close to criticality. We show that while MCT consistently describes gelation at mean-field level, the percolation approach elucidates the geometrical character underlying MCT scaling laws.

  6. A Review of Photocatalysts Prepared by Sol-Gel Method for VOCs Removal

    PubMed Central

    Tseng, Ting Ke; Lin, Yi Shing; Chen, Yi Ju; Chu, Hsin

    2010-01-01

    The sol-gel process is a wet-chemical technique (chemical solution deposition), which has been widely used in the fields of materials science, ceramic engineering, and especially in the preparation of photocatalysts. Volatile organic compounds (VOCs) are prevalent components of indoor air pollution. Among the approaches to remove VOCs from indoor air, photocatalytic oxidation (PCO) is regarded as a promising method. This paper is a review of the status of research on the sol-gel method for photocatalyst preparation and for the PCO purification of VOCs. The review and discussion will focus on the preparation and coating of various photocatalysts, operational parameters, and will provide an overview of general PCO models described in the literature. PMID:20640156

  7. Sol-gel coatings for high power laser optics-past, present and future

    SciTech Connect

    Thomas, I.M.

    1993-12-21

    An investigation into the preparation of sol-gel coatings for high power lasers was started at LLNL in 1983 and AR coatings were successfully developed for use in the Nova laser in 1984. Several other large lasers now use these coatings. Subsequent work on HR coatings resulted in AlOOH/SiO{sub 2} and later ZrO{sub 2} or HfO{sub 2}/SiO{sub 2} systems of good optical performance. The use of organic polymer binders gave increased damage threshold and enhanced optical performance. We are in the process of scaling up HR fabrication for substrates approximately 38 cm square. Concurrently we are developing sol-gel random phase plates for laser beam smoothing. These have a patterned surface design of silica which induces phase shifts in the beam by variation in the optical path length. Plates of this type on 80 cm diameter substrates have been used successfully on the Nova.

  8. Ultrapure glass optical waveguide development in microgravity by the sol-gel process

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Containerless melting of glasses in space for the preparation of ultrapure homogeneous glass for optical waveguides is discussed. The homogenization of the glass using conventional raw materials is normally achieved on Earth either by the gravity induced convection currents or by the mechanical stirring of the melt. Because of the absence of gravity induced convection currents, the homogenization of glass using convectional raw materials is difficult in the space environment. Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation.

  9. Cotton Fabric Surface Modification by Sol-Gel Deposition of ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Vihodceva, S.; Kukle, S.

    2012-08-01

    One of the main tasks of research is to impact the additional value on natural textiles by adding to them ultraviolet (UV) absorption and antimicrobial protection properties with ZnO nano-level coatings. ZnO shows high absorption in the UV region of the light spectrum, in comparison with organic absorbers conventionally used in the textile industry shows no significant degradation, is stable and classified as non-toxic material. Nanosols were prepared by using the sol-gel process. In this work comparison of samples coated by nanosols with zinc acetate (Zn (CH3COO)2-2H2O) and zinc sulphate (ZnSO4) was made. Scanning electron microscopy (SEM) was used to examine the nature of the surface modification with ZnO coating by the sol-gel technique as also after exploitation of samples; energy dispersive X-ray spectroscopy was used for the analysis of elemental composition of coated fabric samples.

  10. Chitosan-silane sol-gel hybrid thin films with controllable layer thickness and morphology.

    PubMed

    Spirk, Stefan; Findenig, Gerald; Doliska, Ales; Reichel, Victoria E; Swanson, Nicole L; Kargl, Rupert; Ribitsch, Volker; Stana-Kleinschek, Karin

    2013-03-01

    The preparation of thin films of chitosan-silane hybrid materials by combining sol-gel processing and spin coating is reported. A variety of silanes can be used as starting materials for the preparation of such thin films, namely tetraethoxysilane, tri-tert-butoxysilanol, trimethylethoxysilane, p-trifluoromethyltetra-fluorophenyltriethoxysilane, trivinylmethoxysilane, (methoxymethyl)trimethyl-silane, and hexamethoxydisilane. These silanes are subjected to a sol-gel process before they are added to acidic chitosan solutions. The chitosan:silane ratio is kept constant at 6:1 (w/w) and dilutions with ethanol are prepared and spin coated. Depending on the degree of dilution, film thickness can be controlled in a range between 5 and 70 nm. For the determination of additional surface properties, static water contact angle measurements and atomic force microscopy have been employed. PMID:23465932

  11. Sol-gel solution-deposited InGaZnO thin film transistors.

    PubMed

    Street, Robert A; Ng, Tse Nga; Lujan, René A; Son, Inyoung; Smith, Matthew; Kim, Sangbok; Lee, Taegweon; Moon, Yongsik; Cho, Sungseo

    2014-03-26

    Thin film transistors (TFTs) fabricated by solution processing of sol-gel oxide semiconductor precursors in the group In-Ga-Zn are described. The TFT mobility varies over a wide range depending on the precursor materials, the composition, and the processing variables, with the highest mobility being about 30 cm(2)/(V s) for IZO and 20 cm(2)/(V s) for IGZO. The positive dark bias stress effect decreases markedly as the mobility increases and the high mobility devices are quite stable. The negative bias illumination stress effect is also weaker in the higher mobility TFTs, and some different characteristic properties are observed. The TFT mobility, threshold voltage, and bias stress properties are discussed in terms of the formation of self-compensated donor and acceptor states, based on the chemistry and thermodynamics of the sol-gel process. PMID:24593772

  12. Cross-condensation reactions in an organically modified silica sol-gel

    SciTech Connect

    Prabakar, S.; Raman, N.K. [New Mexico Univ., Albuquerque, NM (United States); Assink, R.A. [Sandia National Labs., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States)

    1993-12-31

    High resolution {sup 29}Si NMR has been used to study the extent of cross condensation taking place in a hybrid organic/inorganic sol-gel system. Tetraethoxysilane (TEOS) and methltriethoxysilane (MTEOS) sol-gels were chosen for this purpose. The sols were prepared by acid catalyzed hydrolysis of TEOS and MTEOS with a H{sub 2}O/Si ratio of 0.3. {sup 29}Si NMR shows signals due to both self-condensation and cross-condensation between TEOS and MTEOS. Resonance assignments were made by comparing the positions and intensities of peaks in the spectra of single and multicomponent systems. It was found that, within experimental error, the self- and cross-condensation rates are equal and that extensive molecular level mixing takes place during the early stages of the reaction.

  13. Sol gel based fiber optic sensor for blook pH measurement

    SciTech Connect

    Grant, S. A.; Glass, R. S.

    1996-12-19

    This paper describes a fiber-optic pH sensor based upon sol-gel encapsulation of a self-referencing dye, seminaphthorhodamine-1 carboxylate (SNARF-1C). The simple sol-gel fabrication procedure and low coating leachability are ideal for encapsulation and immobilization of dye molecules onto the end of an optical fiber. A miniature bench-top fluorimeter system was developed for use with the optical fiber to obtain pH measurements. Linear and reproducible responses were obtained in human blood in the pH range 6.8 to 8.0, which encompasses the clinically-relevant range. Therefore, this sensor can be considered for in vivo use.

  14. Treatments of paper surfaces with sol-gel coatings for laminated plywood

    NASA Astrophysics Data System (ADS)

    Wang, Shaoxia; Jämsä, Saila; Mahlberg, Riitta; Ihalainen, Petri; Nikkola, Juha; Mannila, Juha; Ritschkoff, Anne-Christine; Peltonen, Jouko

    2014-01-01

    Two silane-based hybrid coatings were developed for surface modification of paper samples with an attempt to improve the hydrophobic properties of the paper surfaces. A phenolic resin was used along with the sol-gel coatings to impregnate the paper samples before they were pressed on to plywood surfaces. The surface characteristics of the sol-gel-coated paper were investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), confocal laser scanning microscopy (CLSM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The surface chemical properties and water absorption of the laminated plywood was also evaluated. It was observed that the hybrid coatings had clearly different effect on the surface properties of the base paper compared to the industrially impregnated paper. The water absorption of the laminated plywood was decreased the most effectively by mixing the phenolic resin with the coating having an octyl group attached to the silane backbone.

  15. Synthesis of the Nanocrystalline Nickel Ferrite by a Novel Mechano Sol-Gel Auto-Combustion Method

    NASA Astrophysics Data System (ADS)

    Shahmirzaei, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

    In this work, a novel method of mechano sol-gel auto-combustion has been developed for production of single phase nickel ferrite nanocrystalline powder, consisting of a sol-gel auto-combustion synthesis followed by a high energy milling process before calcination. Sol-gel auto-combustion was carried out using a gel including citric acid as a reductant and metal nitrates as oxidants. This gel exhibited a self-propagating behavior after ignition in air. The effects of the intermediate high energy milling on the physical properties of the final product after calcination were investigated. The results showed that with a high energy milling of the sol-gel auto-combusted powders with a ball-to-powder mass ratio of 20 for 20 h, the temperature of calcination for synthesis of the single phase ferrite reduced from 1000°C to 700°C and the size of the ferrite crystallites decreased from 72 nm to 15 nm.

  16. Solid solutions of Ni and Co molybdates in silica-dispersed and bulk catalysts prepared by sol-gel and citrate methods

    NASA Astrophysics Data System (ADS)

    Maione, Andrea; Devillers, Michel

    2004-07-01

    Silica-dispersed catalysts based on cobalt, nickel and mixed Ni-Co molybdates of various compositions are prepared by a sol-gel procedure from silicon alkoxides, metal nitrates and ammonium heptamolybdate. For comparative purposes, the corresponding bulk molybdates are obtained by the citrate route. The polymorphism and the textural properties of these catalysts are investigated by means of X-ray diffraction, UV-visible diffuse reflectance spectroscopy and Raman spectroscopy. Their surface and textural characteristics are investigated by X-ray photoelectron spectroscopy and nitrogen or krypton physisorption. In the sol-gel prepared catalysts, the ?-phase of Ni 1- xCo xMoO 4, which is the most active phase in the oxidative dehydrogenation of light alkanes, is stabilized over the whole composition range. In the analogous bulk catalysts prepared by the citrate method, this phase is stabilized only at high Co content ( x?0.55). Dispersion of the active phase in silica is shown to improve the propene productivity in comparison with bulk catalysts obtained by citrate or coprecipitation methods.

  17. Characterization of Sol-gel Encapsulated Proteins using Small-angle Neutron Scattering

    SciTech Connect

    Luo, Guangming [ORNL; Zhang, Qiu [ORNL; Del Castillo, Alexis Rae [ORNL; Urban, Volker S [ORNL; O'Neill, Hugh Michael [ORNL

    2009-01-01

    Entrapment of biomolecules in silica-derived sol-gels has grown into a vibrant area of research since it was originally demonstrated. However, accessing the consequences of entrapment on biomolecules and the gel structure remains a major challenge in characterizing these biohybrid materials. We present the first demonstration that it is possible with small-angle neutron scattering (SANS) to study the conformation of dilute proteins that are entrapped in transparent and dense sol-gels. Using deuterium-labeled green fluorescent protein (GFP) and SANS with contrast variation, we demonstrate that the scattering signatures of the sol-gel and the protein can be separated. Analysis of the scattering curves of the sol-gels using a mass-fractal model shows that the size of the colloidal silica particles and the fractal dimensions of the gels were similar in the absence and presence of protein, demonstrating that GFP did not influence the reaction pathway for the formation of the gel. The major structural difference in the gels was that the pore size was increased 2-fold in the presence of the protein. At the contrast match point for silica, the scattering signal from GFP inside the gel became distinguishable over a wide q range. Simulated scattering curves representing a monomer, end-to-end dimer, and parallel dimer of the protein were calculated and compared to the experimental data. Our results show that the most likely structure of GFP is that of an end-to-end dimer. This approach can be readily applied and holds great potential for the structural characterization of complex biohybrid and other materials.

  18. Sol–gel-entrapped nano silver catalysts-correlation between active silver species and catalytic behavior

    Microsoft Academic Search

    Vasile I. Pârvulescu; Bogdan Cojocaru; Viorica Pârvulescu; Ryan Richards; Zhi Li; Chris Cadigan; Pascal Granger; Pierre Miquel; Chris Hardacre

    2010-01-01

    Silver colloids prepared by reducing AgNO3 in aqueous solution with sodium citrate were embedded in alumina following two different preparation procedures resulting in samples containing 3 and 5wt.% silver. Characterization of these materials using TEM, XPS, XAES, CP\\/MAS NMR, XRD, and adsorption–desorption isotherms of nitrogen showed that embedding the pre-prepared silver colloids into the alumina via the sol–gel procedure preserved

  19. Organic\\/Inorganic Hybrid Electroluminescent Devices Prepared via Sol-Gel Process

    Microsoft Academic Search

    Ji Hwan Keum; Eunjung Kang; Youngkyoo Kim; Won Jeicho; Chang Sik Ha

    1998-01-01

    Organic\\/inorganic hybrid thin film was introduced into organic electroluminescent device (ELD) in order to enhance the device stability. The inorganic network structure was prepared via sol-gel reaction from tetraethoxysilane (TEOS) in the presence of water. 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran(DCM) was used as an organic lumophore. The ELD was fabricated in a simple structure of anode\\/hybrid layer\\/cathode. The turn-on voltage of the ELD was

  20. Ceramic thin films by sol-gel processing as novel materials for integrated humidity sensors

    Microsoft Academic Search

    Enrico Traversa; Guglielmina Gnappi; Angelo Montenero; Gualtiero Gusmano

    1996-01-01

    Thin films based on 10 at% alkali-doped TiO2 and on iron with very large humidity sensitivity were prepared using a sol-gel technique. Prototype humidity sensors were prepared by depositing metal alkoxide solutions onto Al2O3 substrates with comb-type Au electrodes, by dip-coating and heating in air. Heating to 300°C produces continuous films, free of porosity, which appear as layers covering the

  1. Sol—gel processed TiO 2-based thin films as innovative humidity sensors

    Microsoft Academic Search

    Giampiero Montesperelli; Antonio Pumo; Enrico Traversa; Gusmano; Andrea Bearzotti; Angelo Montenero; Guglielmina Gnappi

    1995-01-01

    Active elements for humidity sensors based on alkali-doped and undoped TiO2 films have been prepared by the sol-—gel technique. TiO2-based films are deposited onto Al2O3 substrates with comb-type Au electrodes by dip-coating, from the appropriate solutions, to obtain four different compositions of 1, 3, 6, and 10 at.% Li and K, with respect to the alkali metal\\/Ti system. The humidity-sensing

  2. Sol–gel preparation and in vitro deposition of apatite on porous gelatin–siloxane hybrids

    Microsoft Academic Search

    Lei Ren; Kanji Tsuru; Satoshi Hayakawa; Akiyoshi Osaka

    2001-01-01

    Ca(II) containing porous hybrids of gelatin and 3-(glycidoxypropyl)trimethoxysilane (GPSM) were prepared using a sol–gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A second soaking of

  3. Densification and microstructure of lead zirconate titanate ceramics fabricated from a triol sol–gel powder

    Microsoft Academic Search

    C. Sangsubun; A. Watcharapasorn; S. Jiansirisomboon

    2008-01-01

    Lead zirconate titanate (PZT) nano-powder was prepared by a triol sol–gel process. X-ray diffraction and transmission electron microscopy results showed that as-synthesized amorphous powder started to crystallize at the calcination temperature above 500°C. The crystalline powder was formed into pellets and sintered at temperatures between 900 and 1300°C. Co-existence of tetragonal and rhombohedral phase was observed in all ceramics. Microstructural

  4. Photochemical diodes of a TiO 2 film prepared by a sol-gel method

    Microsoft Academic Search

    S. Sato; H. Koshiba; H. Minakami; N. Kakuta; A. Ueno

    1994-01-01

    Photochemical diodes were prepared using a thin film of TiO2 made from titanium isopropoxide by a sol-gel method. A half part of a conductive SnO2 film plated on a quartz plate was coated with the TiO2 film, and the other parts of the SnO2 substrate were coated with a thin Pt film. The photochemical diode thus prepared shows photocatalytic activity

  5. Electrochemical Urea Biosensor Based on Sol-gel Derived Nanostructured Cerium Oxide

    Microsoft Academic Search

    Anees A Ansari; B D Malhotra

    2012-01-01

    Urease (Urs) and glutamate dehydrogenase (GLDH) have been co-immobilized onto a nanostructured–cerium oxide (Nano-CeO2) film deposited onto a indium-tin-oxide (ITO) coated glass substrate by dip-coating via sol-gel process for urea detection. This nanostructured film has characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscope (SEM) and electrochemical techniques, respectively. The particle size of the Nano-CeO2 film has

  6. Synthesis and characterization of zinc aluminum oxide thin films by sol–gel technique

    Microsoft Academic Search

    A. R Phani; M Passacantando; S Santucci

    2001-01-01

    Crack free, and dense ZnAl2O4 thin films have been prepared by a sol–gel method using aluminum sec-butoxide and zinc acetate. The complete single phase cubic structure of ZnAl2O4 was formed on a silicon (100) substrate at an annealing temperature of 700°C for 5h. As the annealing temperature increased from 700 to 800°C, we did not observe any kind of diffusion

  7. Preparation and characterization of sol–gel derived ZnTiO 3 nanocrystals

    Microsoft Academic Search

    Shu Fen Wang; Feng Gu; Meng Kai Lü; Chun Feng Song; Su Wen Liu; Dong Xu; Duo Rong Yuan

    2003-01-01

    Nanometer scale cubic ZnTiO3 has been synthesized by sol–gel method at a lower temperature (600°C). X-ray diffraction (XRD) analysis shows that the average crystalline size of the sample is ?8–10nm. The cubic to hexagonal phase transition of ZnTiO3 is clearly observed from the XRD patterns of the sample. The thermal behavior of the sample was characterized by the thermogravimetric\\/differenthermal analysis

  8. Preparation and Characterizations of ZnTiO 3 Powders by Sol–Gel Process

    Microsoft Academic Search

    Lili Zhao; Fangqin Liu; Xuewen Wang; Zhiyong Zhang; Junfeng Yan

    2005-01-01

    ZnTiO3 powders were prepared by a sol–gel method. The gelation conditions and the gelation mechanism were investigated. The crystallization behavior and characteristics of the ZnTiO3 were also investigated in detail. The experimental results show that homogenous and translucent gels can be prepared when the gelation conditions are appropriate and the gelation temperature remains constant. The gel structure can be described

  9. Photoluminescence of sol–gel derived ZnTiO 3:Ni 2+ nanocrystals

    Microsoft Academic Search

    Shu Fen Wang; Feng Gu; Meng Kai Lü; Chun Feng Song; Dong Xu; Duo Rong Yuan; Su Wen Liu

    2003-01-01

    Cubic ZnTiO3 nanocrystal doped with Ni2+ ion has been synthesized by sol–gel method at a lower temperature (600 °C). The crystallinity of the doped sample was characterized by the X-ray diffraction (XRD) patterns and the infrared spectra (IR). The photoluminescence (PL) spectra of the sample measured at different excitation wavelength reveal a novel luminescent phenomenon in blue, green and red

  10. Synthesis and characterization of zinc titanate nano-crystal powders by sol–gel technique

    Microsoft Academic Search

    Yee-Shin Chang; Yen-Hwei Chang; In-Gann Chen; Guo-Ju Chen; Yin-Lai Chai

    2002-01-01

    A sol–gel technique including the Pechini process has been employed for the preparation of nano-sized zinc titanate (ZnTiO3) powders. The yielding powders were heated at temperature from 500°C to 1000°C for various times. The ZnTiO3 phase was formed at the beginning of 500°C. The shape of crystalline will be changed from granular to fiber as the calcination temperature increasing from

  11. Surface modification of polyester nonwoven fabrics by Al 2 O 3 sol–gel coating

    Microsoft Academic Search

    Xueliang Xiao; Fang Chen; Qufu Wei; Ning Wu

    2009-01-01

    Nonwoven polyester (PET) fabrics have been extensively studied for various applications. However, the nonwoven PET fabrics\\u000a have poor wettability. In this work, nonwoven PET fabrics were impregnated in a stable and transparent alumina sol that was\\u000a prepared by the hydrolysis of aluminium isopropoxide using the sol–gel technique. The Al2O3 particles were coated on nonwoven PET fabrics after the rolling-drying process.

  12. The detection of hexavalent chromium by organically doped sol-gels

    SciTech Connect

    Wong, P.W.; Mackenzie, J.D. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering

    1994-12-31

    The sol-gel process can be used to produce porous inorganic matrices that are doped with organic molecules. These doped gels can be used as a quantitative method for the spectrophotometric determination of trace concentrations of metallic ions. For the detection of hexavalent chromium, malachite green was used as the dopant. Preliminary results indicate concentrations on the order of 5 ppb are detectable using this method.

  13. Effect of annealing temperature on Ag nano-composite synthesized by sol–gel

    Microsoft Academic Search

    M. Raffi; J. I. Akhter; M. M. Hasan

    2006-01-01

    Composite silicate thin films containing silver nano-particles were prepared on the glass substrate by sol–gel method to investigate the effect of annealing temperature. The sol coated samples were annealed in the oxidative air environment and subsequently reduced in pure hydrogen environment at 400, 500 and 600°C for the formation of silver nano-particles. Evolution of silver nano-particles in the amorphous SiO2

  14. Preparation of core shell particles consisting of cobalt ferrite and silica by sol–gel process

    Microsoft Academic Search

    Shuping Zhang; Dawei Dong; Yu Sui; Zhiguo Liu; Hongxia Wang; Zhengnan Qian; Wenhui Su

    2006-01-01

    Core shell particles consisting of a magnetic core of cobalt ferrite (CoFe2O4) and a shell of silica (SiO2) are prepared by sol–gel process using tetraethylorthosilicate (TEOS) as a precursor of silica, and metallic nitrates as precursors of ferrite. The core shell structure is confirmed by TEM. The magnetic properties of these nanocomposites are measured by PPMS in low temperature and

  15. High temperature oxidation of chromium with nanometric ceria sol–gel coating

    Microsoft Academic Search

    Hui Ming Jin; Lin Nan Zhang

    2008-01-01

    Isothermal oxidation behavior of chromium with and without nanometric sol–gel CeO2 coating is studied at 1000°C in air. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer

  16. Electrochromic performance of sol-gel-deposited CeO2 films

    Microsoft Academic Search

    Nilgun Ozer; John P. Cronin; Sevim Akyuz

    1999-01-01

    Ceria (CeO2) films were prepared by a sol-gel technique onto fluorine doped tin oxide coated glass substrates. The coating solution was derived from cerium ammonium nitrate dissolved in ethanol with diethanolamine used as a complexing agent. Lithium intercalating properties of the films were investigated using cyclic voltammetry (CV) and UV-visible spectroscopy. The electrochemical examinations were performed in a 0.5 M

  17. Sol–gel derived porous ceria powders using cerium glycolate complex as precursor

    Microsoft Academic Search

    Bussarin Ksapabutr; Erdogan Gulari; Sujitra Wongkasemjit

    2006-01-01

    The preparation of ceria powders via a sol–gel process using cerium glycolate complex as precursor has been investigated to study the hydrolysis and condensation of cerium glycolate precursor. The gelation was followed by FT-IR spectroscopy and the evolution of the CeOC and CeOCe bands of the cerium glycolate molecule was analyzed. The intensity of these bands decreased with the hydrolysis

  18. Effect of heat treatment on corrosion properties of sol–gel titania–ceria nanocomposite coating

    Microsoft Academic Search

    A. Ghasemi; T. Shahrabi; A. A. Oskuie; H. Hasannejad; S. Sanjabi

    2010-01-01

    The objective of this work is to study the effect of heat treatment temperature on corrosion resistance of TiO2–CeO2 composite coatings deposited by sol–gel method. TiO2–CeO2 thin films were applied on 316L stainless steel substrates via spin coating technique. The samples were heat treated at different temperatures from 300 to 500°C and the corrosion resistance of the coated samples was

  19. Preparation and characterization of ceria-zirconia ceramics using a sol-gel process

    Microsoft Academic Search

    Zhu Bin; Xia Changrong; Luo Xiaoguang; Meng Guangyao

    1997-01-01

    Both powder and thin film CeOâ-ZrOâ ceramic materials have been successfully prepared via a sol-gel process. In this process, Zr and Ce hydroxide-mixed sols were prepared by hydrolysis of Zr oxychloride and Ce nitrate. The thin films were coated on glass or alumina plates and also alumina tubes by a spin- or dip-coating procedure. The structure and phase of the

  20. Effects of sol-gel coatings on the localized corrosion behavior of 304 stainless steel

    Microsoft Academic Search

    P. P. Trzaskoma-Paulette; A. Nazeri

    1997-01-01

    The corrosion behavior of ceria\\/titania coated 304 stainless steel (304 SS) was studied by anodic polarization measurements in 0.05 N NaCl. Coatings were prepared by sol-gel methods, were approximately 0.5 μm thick and bonded well to the substrate. The as-received stainless steel suffers sensitization at the coating cure temperature of 900 C and a 500 mV decrease in pitting potential

  1. The Nanocrystalline Ceria Sol-Gel Coatings for High Temperature Applications

    Microsoft Academic Search

    F. Czerwinski; J. A. Szpunar

    1997-01-01

    Sol-gel technology was utilized to produce nanocrystalline thin films of CeO2 on substrates with different oxidation resistance at high temperatures. After deposition, the coatings were composed of CeO2 crystallites with a size of 5 nm, randomly oriented on all the substrates. The annealing of gel deposited on Pt and Si substrates was accompanied by evaporation of water and other species

  2. Grain growth in sol–gel derived alumina–zirconia composites

    Microsoft Academic Search

    V. V. Srdic; D. I. SAVIC

    1998-01-01

    Grain-growth kinetics in sol–gel derived alumina–zirconia composites, containing 20 wt% ZrO2 stabilized with 0, 3 and 6 mol% ceria have been examined. The growth of alumina grains was effectively retarded by zirconia particles and a lake of abnormal growth was evident. Coupled grain growth was observed, but only if the required minimal sintering conditions (i.e. minimal sintering density) were reached.

  3. Synthesis of crystalline cerium dioxide hydrosol by a sol–gel method

    Microsoft Academic Search

    Hong-Wei He; Xiao-Qing Wu; Wei Ren; Peng Shi; Xi Yao; Zhi-Tang Song

    A nano-cerium dioxide hydrosol was synthesized via a sol–gel process at the range of room temperature to 65°C with the nonionic surfactant PVP (polyvinylpyrrolidone). The mixture solution of cerium nitrate and urea turned out a visible chemical reaction under the catalysis of ammonia. The X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses indicated the colloidal

  4. The nanocrystalline ceria sol-Gel coatings for high temperature applications

    Microsoft Academic Search

    F. Czerwinski; J. A. Szpunar

    1997-01-01

    Sol-gel technology was utilized to produce nanocrystalline thin films of CeO2 on substrates with different oxidation resistance at high temperatures. After deposition, the coatings were composed of CeO2 crystallites with a size of 5 nm, randomly oriented on all the substrates. The annealing of gel deposited on Pt and Si substrates\\u000a was accompanied by evaporation of water and other species

  5. Sol–gel preparation and characterization of ceria stabilized zirconia minispheres

    Microsoft Academic Search

    J. Judes; V. Kamaraj

    2009-01-01

    A novel processing technique based on sol–gel drop generation method has been developed to prepare fine zirconia minispheres\\u000a for use as grinding media. Zirconium oxalate gel formation from the prepared sol was obtained in proper synthesis condition\\u000a using Zirconium oxy-chloride octahydrate(ZrOCl2·8H2O) as starting material. The transparent oxalate gel was then added dropwise into the setting solution for the formation minispheres.

  6. Optical Sol-Gel-Based Dissolved Oxygen Sensor: Progress Towards a Commercial Instrument

    Microsoft Academic Search

    C. M. Mcdonagh; A. M. Shields; A. K. Mcevoy; B. D. Maccraith; J. F. Gouin

    1998-01-01

    A dissolved oxygen sensor based on fluorescence quenching of the oxygen-sensitive ruthenium complex, [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline]2+, which has been immobilized in a porous silica sol-gel-derived film, is reported. Ormosil sensing films were fabricated using modified silica precursors such as methyltriethoxysilane (MTEOS) and ethyltriethoxysilane (ETEOS) and were dip-coated onto planar glass substrates. Tailoring of the films for dissolved oxygen (DO) sensing is described

  7. Optical and electrochemical characteristics of sol-gel deposited tungsten oxide films: a comparison

    Microsoft Academic Search

    Nilgün Özer

    1997-01-01

    Tungsten oxide (WO3) films prepared by the sol-gel spin coating technique from a solution of tungsten oxychloride (S WO3) and for comparison from tungsten complex precursor (D WO3). Both types of films were analyzed by ellipsometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and cyclic voltammetry (CV). XRD studies showed that both films were amorphous.

  8. In situ ion-beam analysis and modification of sol-gel zirconia thin films

    NASA Astrophysics Data System (ADS)

    Levine, Timothy Edge; Yu, Ning; Kodali, Padma; Walter, Kevin C.; Nastasi, Michael; Tesmer, Joseph R.; Maggiore, Carl J.; Mayer, James W.

    We report the investigation of ion-beam-induced densification of sol-gel zirconia thin films via in situ ion backscattering spectrometry. We have irradiated three regions of a sample with neon, argon, and krypton ions. For each ion species, a series of irradiation and analysis steps were performed using an interconnected 3 MV tandem accelerator. The technique offers the advantages of minimizing the variation of experimental parameters and sequentially monitoring the densification phenomenon with increasing ion dose.

  9. In situ ion-beam analysis and modification of sol-gel zirconia thin films

    NASA Astrophysics Data System (ADS)

    Levine, T. E.; Yu, N.; Kodali, P.; Walter, K. C.; Nastasi, M.; Tesmer, J. R.; Maggiore, C. J.; Mayer, J. W.

    1995-12-01

    We report the investigation of ion-beam-induced densification of sol-gel zirconia thin films via in situ ion backscattering spectrometry. We have irradiated three regions of a sample with neon, argon, and krypton ions. For each ion species, a series of irradiation and analysis steps were performed using an interconnected 3 MV tandem accelerator. The technique offers the advantages of minimising the variation of experimental parameters and sequentially monitoring the densification phenomenon with increasing ion dose.

  10. Calcium phosphate sol-gel-derived coatings on titanium-aluminum-vanadium substrate for biomedical applications

    Microsoft Academic Search

    Lu Gan

    2003-01-01

    Osseointegration of implants to host bone is a necessary requirement for dental and orthopaedic implants. The rate and quality of osseointegration were enhanced through the use of calcium phosphate (Ca-P) films on metallic substrates. The present study investigates the characteristics of Ca-P films applied using sol-gel dip coating methods to sintered porous-surfaced implants. Ca-P films have been formed using Inorganic

  11. DEVELOPMENT OF SOL-GEL-BASED BIOACTIVE PAPER SENSING PLATFORMS TOWARD NEUROTOXIN DETECTION

    Microsoft Academic Search

    Roger Elliot Luckham

    2009-01-01

    We report on a new solid-phase colorimetric bioassay format based on enzyme-catalyzed enlargement of gold nanoparticles (AuNP) that are coentrapped with the enzyme in a sol-gel based silica material. Biocatalysed hydrolysis of the enzyme substrate, acetylthiocholine (ATCh) leads to formation of thiocholine, which in turn reduces Au(III) onto the entrapped nanoparticles, producing particle growth and a concomitant increase in color

  12. Comparative study of the sol–gel processes starting with different substituted Si-alkoxides

    Microsoft Academic Search

    Andrei Jitianu; Alina Britchi; Calin Deleanu; Virgil Badescu; Maria Zaharescu

    2003-01-01

    In the present work a comparative study of the hydrolysis–polycondensation processes of different Si-substituted alkoxides, leading to hybrid materials with covalent –Si–C– bonds, was carried out. The following alkoxides were used: tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS) and vinyltriethoxysilane (VTEOS). Using gas chromatography coupled with mass spectrometry (CG-MS), nuclear magnetic resonance (29Si-NMR) and infrared spectrometry (IR), information about the sol–gel process in

  13. Barium hydroxyapatite nanoparticles synthesized by citric acid sol–gel combustion method

    Microsoft Academic Search

    Zhiliang Xiu; Lue Mengkai; Suwen Liu; Guangjun Zhou; Benyu Su; Haiping Zhang

    2005-01-01

    Barium hydroxyapatite (BaHAP) nanoparticles have been synthesized by citric acid sol–gel combustion method using citric acid as a reductant\\/fuel and nitrate as an oxidant at a relatively low temperature of 600°C. The thermal decomposition of nitrate–citrate xerogel was investigated by thermogravimetric\\/differential thermal analysis (TG\\/DTA) technique. The yielding powders calcined at 600°C have been characterized by Fourier transform infrared (FT-IR), X-ray

  14. Surface Area Study of High Area Cobalt Aluminate Particles Prepared by the Sol-Gel Method

    Microsoft Academic Search

    Marcos Zayat; David Levy

    2002-01-01

    Cobalt aluminate particles were prepared by the sol-gel method, starting from aluminum sec-butoxide and cobalt salts with a Co:Al ratio of 1:3. Samples with the same composition were also prepared by the citrate-gel method from cobalt and aluminum nitrates and citric acid. The particles were calcined to temperatures between 400 and 1000°C, for the formation of the mixed oxide having

  15. The effect of citric acid addition on the formation of sol–gel derived hydroxyapatite

    Microsoft Academic Search

    Wenjian Weng; Gaorong Han; Piyi Du; Ge Shen

    2002-01-01

    In order to improve the gelation in sol–gel preparation of hydroxyapatite by using Ca(NO3)2 and PO(OH)3?x(OEt)x precursors, citric acid was selected as an enhancing gelation additive. Hydroxyapatite derived from the mixed precursor solutions (Ca\\/P molar ratio of 1.67) with citric acid showed a different reaction path from that without citric acid. The addition of citric acid led to formation of

  16. Immobilization of bacteria in silica matrices using citric acid in the sol–gel process

    Microsoft Academic Search

    Gisela S. Alvarez; Martín F. Desimone; Luis E. Diaz

    2007-01-01

    The aim of this work was to use citric acid in the sol–gel process to generate an inorganic polymer that allows bacterial\\u000a survival for long periods of time and to study the influence of different storage temperatures. We compared gram-negative\\u000a Escherichia coli and gram-positive Staphylococcus aureus, immobilized and preserved at different storage temperatures in silica matrices prepared by the method

  17. A study on the effect factors of sol-gel synthesis of yttrium aluminum garnet nanopowders

    Microsoft Academic Search

    Lin Yang; Tiecheng Lu; Hui Xu; Wei Zhang; Benyuan Ma

    2010-01-01

    Yttrium aluminum garnet (YAG) nanopowders were synthesized by sol-gel method using aluminum nitrate, yttrium nitrate, and citric acid as starting materials, de-ionized water, ethanol, and ethylene glycol as solvents, respectively. The phase formation process, state of particle size distribution (PSD), compositions, morphological characteristics, and thermal behavior of the powders were investigated by means of x-ray diffractometry, PSD, Fourier transform infrared,

  18. Formation of superhydrophobic boehmite film on glass substrate by sol-gel method

    Microsoft Academic Search

    Xinhui Fang; Zhijia Yu; Xiangyu Sun; Xinhua Liu; Futao Qin

    2009-01-01

    Superhydrophobic boehmite film has been successfully prepared on a glass substrate by a sol-gel method. A chelated Aluminum-sec-butoxide\\u000a (Al(OBus)3) solution, instead of aluminum hydroxide collosol, was used for the film coating. By immersing the film in boiling water,\\u000a boehmite crystal was formed on a glass substrate. Subsequently, the rough surface was modified with fluoroalkylsilane (FAS).\\u000a The result shows that the

  19. Physical characteristics of heat-treated nano-silvers dispersed in sol gel silica matrix

    Microsoft Academic Search

    A. Babapour; O. Akhavan; R. Azimirad; A. Z. Moshfegh

    2006-01-01

    Silica films containing various concentrations of Ag nanoparticles were deposited on glass slides using a sol-gel process and then heat-treated in air at different temperatures. The films were analysed by using UV-visible spectrophotometry, atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) for their optical, surface morphological as well as structural, and

  20. Development of novel sol-gel indicators (SGI`s) for in-situ environmental measurements

    SciTech Connect

    Livingston, R.R.; Wicks, G.G.; Baylor, L.C.; Whitaker, M.J.

    1993-10-01

    Organic indicator molecules have been incorporated in a porous sol- gel matrix coated on the end of a fiber-optic lens assembly to create sensors for in situ environmental measurements. Probes have been made that are sensitive to pH and uranyl concentration. The use of fiber optics allows the probe to be lowered into a well or bore hole, while support equipment such as a spectrophotometer and computer may be situated hundreds of meters away.

  1. Preparation and antibacterial activity of hybrid materials containing quaternary ammonium salts via sol–gel process

    Microsoft Academic Search

    M. Marini; M. Bondi; R. Iseppi; M. Toselli; F. Pilati

    2007-01-01

    Organic–inorganic hybrid coatings containing quaternary ammonium salts (QAS) bonded to the organic–inorganic network were prepared from tetraethoxysilane and triethoxysilane terminated poly(ethylene glycol)-block-poly(ethylene) using a sol–gel process. They were applied as a thin layer (0.6–1?m) to PE films and the antibacterial activity of the coated films was tested against both Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538)

  2. A TiO2-Sol-Gel Derived Prussian Blue Nanoparticles-Based Glucose Biosensor

    Microsoft Academic Search

    Jianping Li; Sufen Wang; I. M. Ayoub; C. F. Yang

    2007-01-01

    A highly sensitive and selective glucose biosensor was designed by immobilizing glucose oxidase (GOD) on a Prussian blue nanoparticles (nanoPBs) modified glassy carbon electrode using a novel titanic dioxide Solution-Gelation (TiO2-Sol-Gel) technique. Glucose measurement was based on the level of hydrogen peroxide (H2O2) produced concomitantly with the reaction of glucose and oxygen mediated by GOD. NanoPBs catalyze this reaction efficiently

  3. STUDY OF FEXOY-SIO2 NANOPARTICLES OBTAINED BY SOL-GEL SYNTHESIS

    Microsoft Academic Search

    D. Predoi; R. Cléracb; A. Jitianu; M. Zaharescu; M. Crisan; M. Raileanu

    Nanocomposites FexOy-SiO2, with an iron content of 3wt. % has been prepared by the sol- gel method starting from tetraethoxysilane (TEOS) and methyltrietoxysilane (MTEOS) precursors as the SiO2 sources. This original method produces large quantities of amorphous gels that are thermally treated at 550 ºC and 1000 ºC as the final step of the synthesis. The average diameter of iron

  4. Size-controlled synthesis of nano ?-alumina particles through the sol–gel method

    Microsoft Academic Search

    F. Mirjalili; M. Hasmaliza; L. Chuah Abdullah

    2010-01-01

    Nano ?-alumina particles were synthesized by a sol–gel method using aqueous solutions of aluminum isopropoxide and 0.5M aluminum nitrate. 1\\/3-benzened disoulfonic acid disodium salt (SDBS) and sodium bis-2-ethylhexyl sulfosuccinate (Na(AOT)) were used as surfactant stabilizing agents. Solution was stirred for different periods (24, 36, 48 and 60h) at 60°C. The samples were then analyzed by X-ray diffraction (XRD), scanning electron

  5. Synthesis of nano-sized ceramic powders using precipitated silica in aqueous sol-gel method

    Microsoft Academic Search

    N. N. Ghosh; P. Pramanik

    1997-01-01

    Many multicomponent nano-sized ceramic powders have been prepared using an aqueous sol-gel method. Metal formates and precipitated silica were used as precursors and water was used as reaction medium. The gels prepared by this method were dried at 100 °C for 24 h and calcined at different temperatures. X-ray powder diffraction. Thermal analysis (TGA and DTA), and I.R. spectroscopy analysis

  6. Aqueous sol–gel synthesis of lanthanum phosphate nano rods starting from lanthanum chloride precursor

    Microsoft Academic Search

    Sasidharan Sankar; Krishna Gopakumar Warrier

    2011-01-01

    Aqueous sol–gel technique is reported for synthesizing nanosize, rod shaped lanthanum phosphate particles starting from lanthanum\\u000a chloride, which is suitable for variety of applications such as machinable ceramics, thermal barrier coatings and luminescent\\u000a materials. The phosphate particles are having rod like morphology having an overall size in the range 25–100 nm and with an\\u000a average aspect ratio 4. The morphology is

  7. Economical synthesis of nano alumina powder using an aqueous sol–gel method

    Microsoft Academic Search

    M. Shojaie-Bahaabad; E. Taheri-Nassaj

    2008-01-01

    Nano alumina powder can be widely used in the fields of electronics, catalyst supports and high temperature applications. In the present article, a nano Al2O3 powder was synthesized by a simple aqueous sol–gel method using inexpensive AlCl3·6H2O and Al powder as raw materials. It was shown that the gel calcined at 1100 °C resulted in the formation of a crystalline ?-Al2O3

  8. Transparent MgF 2-films by sol–gel coating: Synthesis and optical properties

    Microsoft Academic Search

    Hannes Krüger; Erhard Kemnitz; Andreas Hertwig; Uwe Beck

    2008-01-01

    Dielectric, anti-reflective or high reflective systems consist of low and high refractive index layers. Common systems are oxides. The preparation of low refractive index MgF2-films of optical quality by means of an anhydrous low temperature sol–gel synthesis is presented. The MgF2-sol is prepared by spin-coating on silicon and glass substrates. Various film thicknesses between 20 nm and 435 nm have been deposited.

  9. ITO films on glass substrate by sol–gel technique: synthesis, characterization and optical properties

    Microsoft Academic Search

    E. Celik; U. Aybarc; M. F. Ebeoglugil; I. Birlik; O. Culha

    2009-01-01

    The present paper extensively demonstrates synthesis, characterization and optical properties of semiconductor indium tin\\u000a oxide (ITO) thin films on glass substrate using sol–gel technique for gas sensor applications. Turbidity, pH values, wettability\\u000a and rheological properties of the prepared solutions were measured to determine solution characteristics by turbidimeter,\\u000a pH meter, contact angle goniometer and rheometer machines prior to coating process. Thermal,

  10. Sol-gel synthesis of zeolite coatings and their application in catalytic microstructured reactors

    Microsoft Academic Search

    E. V. Rebrov

    2009-01-01

    Sol-gel hydrothermal synthesis is one of the most promising methods for the obtaining of zeolitic coatings (films, membranes)\\u000a on the internal surface of channels of catalytic microstructured reactors. In this review, we discuss the basic methods for\\u000a the synthesis of zeolite coatings, the processes that influence the rate of crystallization and crystal growth on a substrate,\\u000a and the methods for

  11. Sol–gel synthesis and characterization of Ce doped-BaTiO 3

    Microsoft Academic Search

    Marin Cernea; Odile Monnereau; Philip Llewellyn; Laurence Tortet; Carmen Galassi

    2006-01-01

    Barium titanate (BaTiO3) have been doped “in situ” with 5.5mol% cerium by a sol–gel method using barium acetate, titanium (IV) isopropoxide, and cerium (III) acetylacetonate as starting materials. The dried gel showed a microstructure consisting of nano-sized grains (?140nm) with great tendency to agglomeration. Several thermal analysis techniques were used to study the decomposition process of the gel. The presence

  12. Sol–gel synthesis of inorganic complex fluorides using trifluoroacetic acid

    Microsoft Academic Search

    Shinobu Fujihara; Sachiko Ono; Yoko Kishiki; Munehiro Tada; Toshio Kimura

    2000-01-01

    A sol–gel method to prepare inorganic complex fluorides, SrAlF5 and BaMgF4 is described. Metal acetates and alkoxide were used as starting materials, and trifluoroacetic acid was used as a fluorine source. The formation of the fluorides was examined using thermal analysis, X-ray diffraction (XRD) and infrared (IR) absorption. The fluorides were formed through the highly exothermic decomposition reaction of trifluoroacetate

  13. Preparation and properties of ZnO thin films deposited by sol-gel technique

    Microsoft Academic Search

    Wei Lan; Xingping Peng; Xueqin Liu; Zhiwei He; Yinyue Wang

    2007-01-01

    Zinc oxide (ZnO) thin films were deposited on (100) Si substrates by sol-gel technique. Zinc acetate was used as the precursor\\u000a material. The effect of different annealing atmospheres and annealing temperatures on composition, structural and optical\\u000a properties of ZnO thin films was investigated by using Fourier transform infrared spectroscopy, X-ray diffraction, atomic\\u000a force microscopy and photoluminescence (PL), respectively. At an

  14. Synthesis and characterisation of cadmium titanium oxide thin films by sol–gel technique

    Microsoft Academic Search

    A. R. Phani; M. Passacantando; S. Santucci

    2002-01-01

    Crack free, dense and transparent CdTiO3 thin films have been prepared by sol–gel technique using titanium butoxide and cadmium acetate. The formation of the CdTiO3 phase started from 500°C annealing temperature onwards. The complete orthorhombic structure of CdTiO3 was formed on Silicon (100) substrate at an annealing temperature of 600°C for 5h. As the annealing temperature increased from 600 to

  15. Synthesis and characterization of lead strontium titanate thin films by sol–gel technique

    Microsoft Academic Search

    M Jain; S. B Majumder; R Guo; A. S Bhalla; R. S Katiyar

    2002-01-01

    A series of strontium doped lead titanate (PbxSr1?xTiO3) thin films were deposited on platinized silicon substrates by sol–gel technique and were characterized for their phase purity, surface morphology, dielectric and leakage current characteristics. The grain size of lead titanate thin films was systematically reduced with the increase in strontium content. With the addition of 50 at.% strontium doping, at room

  16. Preparation of EuO films by sol-gel technique

    SciTech Connect

    Yi, G.; Batalla, E. [Department of Physics, Royal Military College, Kingston, Ontario, Canada, K7K 5L0 (CANADA)

    1996-10-01

    EuO thin films with the cubic NaCl structure were fabricated by a sol-gel technique. The composition and crystal structure of the films were investigated as a function of firing temperature. The preparation of the stock solution and the coating and firing of the films are described. The firing of the gel film and the reduction of the Eu{sub 2}O{sub 3} phase are also discussed. {copyright} {ital 1996 Materials Research Society.}

  17. Preparation of Ga 2 Se 3 thin films by sol–gel technique

    Microsoft Academic Search

    Ibrahim H. Mutlu; Maharram Z. Zarbaliyev; Ferhat Aslan

    2009-01-01

    In this study we describe the preparation of Ga2Se3 semiconductor compound thin films by sol–gel method for different crystal formation temperatures. The films were characterized\\u000a by X-ray diffraction analyses (XRD), UV–visible spectrometer, and scanning electron microscope (SEM). The XRD spectrum showed\\u000a that the formation of Ga2Se3 crystals were between 743 and 823 K. The thin film crystals that were formed at

  18. Indium-doped ZnO thin films deposited by the sol–gel technique

    Microsoft Academic Search

    E. J. Luna-Arredondo; A. Maldonado; R. Asomoza; D. R. Acosta; M. A. Meléndez-Lira; M. de la L. Olvera

    2005-01-01

    Conducting and transparent indium-doped ZnO thin films were deposited on sodocalcic glass substrates by the sol–gel technique. Zinc acetate and indium chloride were used as precursor materials. The electrical resistivity, structure, morphology and optical transmittance of the films were analyzed as a function of the film thickness and the post-deposition annealing treatments in vacuum, oxygen or argon. The obtained films

  19. Development of nanograined hexagonal barium ferrite thin films by sol–gel technique

    Microsoft Academic Search

    Nimai Chand Pramanik; Tatsuo Fujii; Makoto Nakanishi; Jun Takada

    2005-01-01

    Nanograined hexagonal barium ferrite (BaFe12O19) thin films have been developed on naturally oxidized Si substrates by sol–gel technique using aqueous solution of metal chlorides. Coated films were heat treated at different temperatures ranging from 450 to 900 °C, and all the films were characterized by using X-ray diffraction (XRD), inductive coupled plasma (ICP) spectroscopy, and field emission scanning electron microscopy

  20. Fabrication of La2Ti2O7 thin films by a sol-gel technique

    Microsoft Academic Search

    A. V. Prasadarao; U. Selvaraj; S. Komarneni; A. S. Bhalla

    1992-01-01

    Sol-gel thin films of La2Ti2O17 were deposited on fused silica and Si( 100) substrates by a spin-coating process. The La2Ti2O17 precursor solution for the spin-coating was prepared from lanthanum acetylacetonate and titanium iso-propoxide dissolved in 2-methoxyethanol. Crystalline and crack-free films of ? 0.3 ?m thickness were deposited on the above sulastrates using a single coating and followed by annealing at

  1. Electrical and Optical Properties of MgO Thin Film Prepared by Sol-Gel Technique

    Microsoft Academic Search

    In-Chyuan Ho; Yuhuan Xu; John D. Mackenzie

    1997-01-01

    MgO thin films with either (111) or (200) preferential orientation have been prepared on (100) Si substrates by sol-gel method after a heat-treatment at 800°C. The obtained (111) preferentially oriented MgO film has a dielectric constant of 7.0 with a loss factor of 5% and a dielectric strength higher than 8 × 105 V\\/cm. The optical refractive index, which depends

  2. Optical and Structural Properties of Nanostructured Oxide Thin Films by Sol-Gel Technique

    Microsoft Academic Search

    K. S. A. Kareem; K. Narasimha Rao; A. R. Phani; R. Uma Rani; A. K. Sharma

    2011-01-01

    TiO2 and Al2O3 are commonly used materials in optical thin films in the visible and near-infrared wavelength region due to their high transparency and good stability. In this work, TiO2 and Al2O3 single, and nano composite thin films with different compositions were deposited on glass and silicon substrates at room temperature using a sol-gel spin coater. The optical properties like

  3. Electrical and optical properties of MgO thin film prepared by sol-gel technique

    Microsoft Academic Search

    In-Chyuan Ho; Yuhuan Xu; John D. Mackenzie

    1997-01-01

    MgO thin films with either (111) or (200) preferential orientation have been prepared on (100) Si substrates by sol-gel method\\u000a after a heat-treatment at 800C. The obtained (111) preferentially oriented MgO film has a dielectric constant of 7.0 with\\u000a a loss factor of 5% and a dielectric strength higher than 8105 V\\/cm. The optical refractive index, which depends on the

  4. Eu-doped indium tin oxide thin films fabricated by sol–gel technique

    Microsoft Academic Search

    Jung Kyun Kim; Yong Gyu Choi

    2009-01-01

    We have fabricated Eu-doped indium tin oxide thin films via the conventional sol–gel technique, and confirmed that the doped Eu atoms were chemically incorporated into the indium tin oxide lattice by substituting the In sites. Optical spectra indicated that the Eu-doped films were free of any impurities leading to additional vibrational effects. Valence states of Eu ions in our Eu-doped

  5. Lead-based titanate ferroelectric thin films fabricated by a sol–gel technique

    Microsoft Academic Search

    D. G. Wang; C. Z. Chen; J. Ma; T. H. Liu

    2008-01-01

    Because of its excellent ferroelectric properties including piezoelectricity, thermoelectricity and photoelectricity, the lead-based titanate ferroelectric thin films have been widely used in the high-tech fields such as microelectronics, optoelectronics, integrated optics and microelectro-mechanical system. As a significant technique in preparing thin films, the sol–gel method has achieved great success in preparing the lead-based titanate ferroelectric thin films. In this paper,

  6. Magnetic properties of cobalt ferrite nanoparticles synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    George, T.; Sunny, A. T.; Varghese, T.

    2015-02-01

    Cobalt ferrite nanoparticles of average size 18 nm are synthesized by sol-gel method and investigated the magnetic properties. The saturation magnetization value calculated from vibration sample magnetometer (VSM) studies for CoFe2O4 is lower than the reported value for the bulk. The magnetization curves demonstrate a trend towards the superparamagnetic behavior of the as-prepared CoFe2O4 nanoparticles. The microwave magnetic parameters show a decreasing trend with the increase of frequency.

  7. Sol-Gel Preparation and Properties of Fluoride-Substituted Hydroxyapatite Powders

    Microsoft Academic Search

    Hae-Won Kim; Long-Hao Li; Young-Hag Koh; Jonathan C. Knowles; Hyoun-Ee Kim

    2004-01-01

    Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) pow- ders were synthesized by a sol-gel method for usage as bone filler and drug carrier. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water-based solu- tion. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of FHA powders. With heat treatment above 400°C, a characteristic apatite phase was observed

  8. Preparation of (Pb,Sr)TiO3 Films by Sol-Gel Technique

    Microsoft Academic Search

    Tadashi Fujii; Masatoshi Adachi

    2005-01-01

    Ferroelectric (Pb,Sr)TiO3 (PST) thin films with a perovskite structure were prepared by the sol-gel technique. PST precursor solutions were prepared from lead (II) acetate, titanium tetraisopropoxide, and strontium acetate hemihydrate with solvents of acetic acid and 2-methoxyethanol. The PST film fabricated on an Ir\\/SiO2\\/Si substrate with a perovskite structure exhibited a ferroelectric hysteresis curve. The Pb\\/Sr ratio of the PST

  9. High second-order optical nonlinearities in thermally poled sol-gel silica

    Microsoft Academic Search

    V. Pruneri; G. Bonfrate; P. G. Kazansky; H. Takebe; K. Morinaga; M. Kohno; K. Kuwasaki; T. Takeuchi

    1999-01-01

    Silica glass samples prepared by a sol-gel process, the mixture of silica sol for gelation and colloidal silica particles, have been thermally poled in vacuum by continuous high voltage (8-12 kV) at elevated temperature (280 °C). High second-order nonlinearities (>1 pm\\/V), located under the anodic surface, have been measured and the values are higher than those obtained in fused silica

  10. Fabrication of high-purity silica glass through the WSPA-sol-gel process

    Microsoft Academic Search

    M. Toki; T. Takeuchi; S. Miyasita; S. Kanbe

    1992-01-01

    High-purity and large-size silica glass was prepared by a wet process silica and pH adjustment (WSPA)-sol-gel process which involved the following steps: (1) colloidal silica synthesis through the hydrolysis reaction of TEOS catalysed by ammonia solution; (2) sol preparation through the hydrolysis reaction of TEOS by hydrochloric acid; (3) mixing the colloidal silica and sol solution; (4) adjusting the pH

  11. The chemistry of and physics with porous sol-gel glasses

    Microsoft Academic Search

    M. W. Shafer; D. D. Awschalom; J. Warnock; G. Ruben

    1987-01-01

    Porous media with well-defined pore diameters can be employed as hosts within which one may study a wealth of physical phenomena in well-characterized confining geometries. In this paper we describe the procedures for forming variable pore size glasses via the sol-gel process. Two general methods were used to form the gels from which the porous glasses were formed; the hydrolysis

  12. Characteristics of Nanohybrid Coating Films Synthesized from Colloidal Silica and Organoalkoxysilanes by Sol-Gel Process

    Microsoft Academic Search

    Moonkyong Na; Dongpil Kang; Myeongsang Ahn; Heewoong Lee

    2008-01-01

    Organic-inorganic hybrid sols were synthesized using colloidal silica and organoalkoxysilane using the sol-gel process. Hybrid sols were functionalized using methyltrimethoxysilane (MTMS) and gamma-glycidoxypropyltrimethoxysilane (GTMS). Coating films were formed on a glass substrate using a spin coating procedure. The hybrid sols were evaluated for stability and thermal degradation. Viscosity increased markedly when the hybrid sols were reacted for 10 d. It

  13. Rare earth ions, their spectroscopy of cryptates and related complexes in sol–gel glasses

    Microsoft Academic Search

    Renata Reisfeld; Tsiala Saraidarov; Michael Gaft; Marek Pietraszkiewicz; Oksana Pietraszkiewicz; S?awomir Bianketti

    2003-01-01

    A number of europium and terbium complexes were incorporated into glass films prepared by the sol–gel method. The selected films consisted of zirconium oxide, zirconium oxide-glymo and zirconium-silica-polyurethane (ZSUR). The short theory of rare earth spectra and their transition probabilities and non-radiative relaxations are outlined. Steady state and dynamic laser excited luminescence reveal an increase of the emission intensity of

  14. Formation of copper and silver nanometer dimension clusters in silica by the sol-gel process

    Microsoft Academic Search

    G. de; L. Tapfer; M. Catalano; G. Battaglin; F. Caccavale; F. Gonella; P. Mazzoldi; R. F. Haglund Jr.

    1996-01-01

    Ag and Cu (pure and\\/or mixture) nanoclusters doped silica films were prepared by the sol-gel process. In the case of Ag and Cu codoped silica films, Cu\\/Ag molar ratio was 1, 2, and 3 at constant (Ag+Cu)\\/SiO2 molar ratio of 0.175. Separated Ag and Cu nanoclusters are formed in the silica matrix. The size of the clusters and their distribution

  15. Encapsulation of Proteins in Transparent Porous Silicate Glasses Prepared by the Sol-Gel Method

    Microsoft Academic Search

    Lisa M. Ellerby; Clinton R. Nishida; Fumito Nishida; Stacey A. Yamanaka; Bruce Dunn; Joan Selverstone Valentine; Jeffrey I. Zink

    1992-01-01

    Novel sol-gel synthetic techniques were used to immobilize copper-zinc superoxide dismutase (CuZnSOD), cytochrome c, and myoglobin (Mb) by encapsulation in stable, optically transparent, porous silica glass matrices under mild conditions such that the biomolecules retained their characteristic reactivities and spectroscopic properties. The resulting glasses allowed transport of small molecules into and out of the glasses at reasonable rates but nevertheless

  16. Ultrapure glass optical waveguide: Development in microgravity by the sol gel process

    NASA Technical Reports Server (NTRS)

    Mukherjee, S. P.; Debsikdar, J. C.; Beam, T.

    1983-01-01

    The sol-gel process for the preparation of homogeneous gels in three binary oxide systems was investigated. The glass forming ability of certain compositions in the selected oxide systems (SiO-GeO2, GeO2-PbO, and SiO2-TiO2) were studied based on their potential importance in the design of optical waveguide at longer wavelengths.

  17. Al 2 O 3 -based pigments synthesized by a new proteic sol–gel method

    Microsoft Academic Search

    Ronaldo S. Silva; Zélia S. Macedo

    2011-01-01

    Alumina-based pigments were synthesized by the proteic sol–gel method. In this method, coconut water is employed as polymeric\\u000a agent instead of the conventional alkoxide precursors. To this study, three common chromophore metallic ions (Mn3+, Co3+, and Cr3+) were chosen in order to verify the method efficiency. Differential thermal analysis (DTA), thermogravimetry (TG), and XRD\\u000a techniques were used to characterize the

  18. Use of sol-gel thin films in solar energy applications

    Microsoft Academic Search

    R. B. Pettit; C. J. Brinker

    1985-01-01

    The sol-gel process uses metal alkoxides of network forming cations, such as Si, B, or Al, in alcohol\\/water solutions to form glass-like, polymeric networks in liquid solution. Thin films are formed by depositing the solution on a substrate by spinning, dipping or spraying. When the film is then heated to moderate temperatures (400 to 500°C), dense glass films or stable

  19. CO 2 capture using mesoporous alumina prepared by a sol–gel process

    Microsoft Academic Search

    Chao Chen; Wha-Seung Ahn

    2011-01-01

    Mesoporous alumina (MA) having high surface area (812m2\\/g) and large pore volume (0.83cm3\\/g) with a narrow pore size distribution was prepared by a simple sol–gel process. The as-prepared MA was characterized by XRD, N2 adsorption–desorption isotherms, and transmission electron microscopy (TEM). The CO2 adsorption performance of MA was tested under both low (<1bar) pressure using a static volumetric system and

  20. Waveguided visible lasing effects in a dye-doped sol-gel glass film

    Microsoft Academic Search

    I. Finkelstein; S. Ruschin; Y. Sorek; R. Reisfeld

    1997-01-01

    We report the first laser action in wavelength films of dye-doped sol-gel glass. Rhodamine B (RB)-doped films were prepared that were pumped by frequency-doubled Nd:YAG laser light focused by means of cylindrical lens. Fresnel back-reflections of the order of a few percent at the edge of the film provided sufficient feedback to change significantly the characteristics of the emitted light.

  1. Active optical properties of Er-containing crystallites in sol–gel derived glass films

    Microsoft Academic Search

    C. Strohhöfer; J Fick; H. C Vasconcelos; R. M Almeida

    1998-01-01

    Thin films of controlled refractive index are prepared by sol–gel processing and thick multilayer deposits are used as planar waveguides for integrated optics (IO). By doping these layers with rare-earth ions such as Nd3+ or Er3+, IO devices such as lasers or amplifiers can be fabricated; the incorporation of these active elements into crystallites offers possibilities for increased dopant concentration

  2. Enhancement of electrochemical performance of lithium iron phosphate by controlled sol–gel synthesis

    Microsoft Academic Search

    Jae-Kwang Kim; Jae-Won Choi; Ghanshyam S. Chauhan; Jou-Hyeon Ahn; Gil-Chan Hwang; Jin-Beom Choi; Hyo-Jun Ahn

    2008-01-01

    The porous phase pure lithium iron phosphate (LiFePO4\\/C) composite particles with a few nanometers thick layer of carbon were synthesized by sol–gel method. The in situ coating of carbon on the LiFePO4 particles was achieved by the pyrolysis of carbon source during the thermal treatment. The synthetic conditions were observed to affect physical, morphological and electrochemical properties of the composites.

  3. Zinc selenide (ZnSe) nanoparticles prepared by sol-gel method

    Microsoft Academic Search

    Sabar D. Hutagalung; Siaw C. Loo

    2007-01-01

    ZnSe nanoparticles embedded in SiO2 thin films were prepared by sol-gel method using zinc acetate dihydrate, selenic acid and TEOS as source materials. The ZnSe nanoparticles\\/SiO2 thin film composites were deposited on the glass substrate by dip coating technique. FESEM images show that morphology of embedded ZnSe nanoparticles affected by ZnSe\\/SiO2 molar ratio. The optical properties of thin film composite

  4. Characterization of sol-gel-prepared Ti02 thin film for O2 sensing

    Microsoft Academic Search

    Massood Z. Atashbar; Muralidhar K. Ghantasala; Wojtek Wlodarski

    1997-01-01

    This paper presents the results of our investigation on deposition and characterization of sol-gel prepared TiO2 thin films for oxygen sensing applications. The properties of pure TiO2 thin films are compared with those doped with niobium oxide and 1%pt. These films are characterized using Rutherford backscattering spectroscopy (RBS), x-ray diffraction (XRD) and scanning electron microscopy (SEM) to study their chemical

  5. Nanostructural control of the release of macromolecules from silica sol–gels

    PubMed Central

    Radin, Shula; Bhattacharyya, Sanjib; Ducheyne, Paul

    2013-01-01

    The therapeutic use of biological molecules such as growth factors and monoclonal antibodies is challenging in view of their limited half-life in vivo. This has elicited the interest in delivery materials that can protect these molecules until released over extended periods of time. Although previous studies have shown controlled release of biologically functional BMP-2 and TGF-? from silica sol–gels, more versatile release conditions are desirable. This study focuses on the relationship between room temperature processed silica sol–gel synthesis conditions and the nanopore size and size distribution of the sol–gels. Furthermore, the effect on release of large molecules with a size up to 70 kDa is determined. Dextran, a hydrophilic polysaccharide, was selected as a large model molecule at molecular sizes of 10, 40 and 70 kDa, as it enabled us to determine a size effect uniquely without possible confounding chemical effects arising from the various molecules used. Previously, acid catalysis was performed at a pH value of 1.8 below the isoelectric point of silica. Herein the silica synthesis was pursued using acid catalysis at either pH 1.8 or 3.05 first, followed by catalysis at higher values by adding base. This results in a mesoporous structure with an abundance of pores around 3.5 nm. The data show that all molecular sizes can be released in a controlled manner. The data also reveal a unique in vivo approach to enable release of large biological molecules: the use more labile sol–gel structures by acid catalyzing above the pH value of the isoelectric point of silica; upon immersion in a physiological fluid the pores expand to reach an average size of 3.5 nm, thereby facilitating molecular out-diffusion. PMID:23643607

  6. Superhydrophobic cotton fabrics prepared by one-step water-based sol–gel coating

    Microsoft Academic Search

    Lihui Xu; Wei Zhuang; Bi Xu; Zaisheng Cai

    2012-01-01

    A simple one-step superhydrophobic coating method for cotton fabrics based on a modified silica hydrosol is presented in this study. The modified silica hydrosol was prepared by the co-hydrolysis\\/co-condensation of methyl trimethoxy silane and a non-fluoro compound, hexadecyltrimethoxysilane, via water-based sol–gel reaction under alkaline condition in the presence of a surfactant. The as-obtained products were characterized by particle size analyzer,

  7. Superhydrophobic cotton fabrics prepared by one-step water-based sol–gel coating

    Microsoft Academic Search

    Lihui Xu; Wei Zhuang; Bi Xu; Zaisheng Cai

    2011-01-01

    A simple one-step superhydrophobic coating method for cotton fabrics based on a modified silica hydrosol is presented in this study. The modified silica hydrosol was prepared by the co-hydrolysis\\/co-condensation of methyl trimethoxy silane and a non-fluoro compound, hexadecyltrimethoxysilane, via water-based sol–gel reaction under alkaline condition in the presence of a surfactant. The as-obtained products were characterized by particle size analyzer,

  8. Preparation of durable superhydrophobic surface by sol–gel method with water glass and citric acid

    Microsoft Academic Search

    Jinyun Liu; Wenqi Huang; Yanjun Xing; Rong Li; Jinjin Dai

    2011-01-01

    Durable superhydrophobic surface on cotton fabrics has been successfully prepared by sol–gel method. Cellulose fabric was\\u000a first coated with silica sol prepared with water glass and citric acid as the acidic catalyst. The silica coated fabric was\\u000a then padded with hydrolyzed hexadecyltrimethoxysilane afterwards obtaining low surface energy. Water contact angle and hydrostatic\\u000a pressure were used to characterize superhydrophobicity and washing

  9. High surface area neodymium phosphate nano particles by modified aqueous sol–gel method

    Microsoft Academic Search

    Sasidharan Sankar; Krishna Gopakumar Warrier; Rajesh Komban

    2011-01-01

    Synthesis of nano rod shaped neodymium phosphate (NdPO4) particles with specific surface area as high as 107m2g?1 and an average length of 50nm with aspect ratio 5 was achieved using modified sol gel method. Crystallite size calculated from the X-ray diffraction data by applying Scherer equation was 5nm for the precursor gel after calcination at 400°C. NdPO4 was first precipitated

  10. Solid oxide fuel cells developed by the sol-gel process for oxygen generation

    Microsoft Academic Search

    Joshua S. Finch

    2008-01-01

    Electrochemical fuel cells convert chemical energy directly to electrical energy through the reaction of a fuel and an oxidant. Solid oxide fuel cells (SOFC) are solid-state devices that operate at temperatures around 800°C, using a solid oxygen electrolyte. The goal of this thesis is to prepare a defect-free solid oxygen electrolyte by a sol-gel process that is capable of (a)

  11. Optical properties and electrochromic characterization of sol–gel deposited ceria films

    Microsoft Academic Search

    Nilgün Özer

    2001-01-01

    Ceria (CeO2) films were deposited by the sol–gel spin coating process and optical and electrochromic properties have been investigated. Ceria coating solutions were prepared using cerium amonium nitrate and ethanol. The films were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-visible (UV–Vis) spectroscopy and cyclic voltammetry. XRD analysis of the films showed that they

  12. Sol–gel derived highly transparent and conducting yttrium doped ZnO films

    Microsoft Academic Search

    Ravinder Kaur; A. V. Singh; R. M. Mehra

    2006-01-01

    This paper reports the structural, electrical and optical properties of Yttrium doped zinc oxide (YZO) thin films deposited on Corning (7059) glass substrates by spin coating technique. A precursor solution of ZnO, 0.2M in concentration was prepared from zinc acetate dissolved in anhydrous ethanol with diethanolamine as a sol gel stabilizer. Yttrium nitrate hexahydrate (Y2NO3·6H2O) was used as the dopant

  13. Fabrication of tin oxide film by sol–gel method for photovoltaic solar cell system

    Microsoft Academic Search

    Seung-Chul Lee; Jae-Ho Lee; Tae-Sung Oh; Young-Hwan Kim

    2003-01-01

    Transparent conducting tin(IV) oxide thin films have been developed with a sol–gel method, which is a low-cost process for the electrode materials of solar cell substrate. The precursor solution was made of tin isopropoxide dissolved in isopropyl alcohol. The hydrolysis rate was controlled by the addition of triethanolamine. Dipping and spin-coating technique were applied to coat tin oxide on borosilicate

  14. Sol-Gel Synthesis of Vanadate-Based Thin Films as Counter Electrodes in Electrochromic Devices

    Microsoft Academic Search

    Riccardo Ceccato; Giovanni Carturan; Franco Decker; Florinda Artuso

    2003-01-01

    V2O5-based thin films were prepared via the sol-gel method in order to obtain semiconductive films suitable as counter electrodes in electrochemical devices (e.g. electrochromic windows). Different metal precursors (nickel 2,4-pentanedionate, NiCl2, BiCl3, SbCl3) were added, after dissolution, into the starting vanadium oxo-triisopropoxide solution in the presence of acetic acid as a chelating agent. Preventing different synthesis conditions due to the

  15. Optical and electrochemical properties of V 2O 5:Ta Sol–Gel thin films

    Microsoft Academic Search

    César O. Avellaneda; Luis O. S. Bulhões

    2006-01-01

    Vanadium and tantalum-doped vanadium pentoxide, V2O5 and V2O5:Ta thin films (2.5 and 5mol% of Ta) were prepared using sol–gel dip-coating technique.The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent.The films were deposited on a transparent glass substrate with ITO conducting film by dip-coating technique, with a withdrawal

  16. Electrochromic performance of sol–gel deposited V 2O 5:Ta films

    Microsoft Academic Search

    César O. Avellaneda

    2007-01-01

    Vanadium and tantalum-doped vanadium pentoxide, V2O5 and V2O5:Ta thin films (2.5 and 5mol% of Ta) were prepared using sol–gel dip coating technique.The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent.The films were deposited on a transparent glass substrate with ITO conducting film by dip coating technique, with

  17. Probing the sol–gel transition of egg white proteins by pulsed-NMR method

    Microsoft Academic Search

    K. S. Goh; Rajeev Bhat; A. A. Karim

    2009-01-01

    The utility of pulsed NMR spectroscopy as a convenient means to monitor a sol–gel transition during heat-induced gelation\\u000a of egg white proteins was investigated. This is based on the notion that, regardless of the mechanism of gel formation, the\\u000a transition from sol to a gel state in such system is accompanied by the appearance of solid-like domain and a concomitant

  18. Electrochromism in sol-gel deposited TiO2 films

    Microsoft Academic Search

    John M. Bell; Joanna Barczynska; L. A. Evans; Kathleen A. MacDonald; J. Wang; David C. Green; Geoffrey B. Smith

    1994-01-01

    Electrochromism is sol-gel deposited TiO2 films and films containing TiO2 and WO3 has been observed. The films are deposited by dip-coating from a precursor containing titanium isopropoxide in ethanol or titanium propoxide in ethanol, and after deposition the films are heat treated to between 250 degree(s)C and 300 degree(s)C. The films do not show any signs of crystallinity. However substantial

  19. The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

    Microsoft Academic Search

    Corrie Leigh Carnes

    2000-01-01

    The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3\\/MgO and ZnO\\/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR,

  20. Synthesis of YAG powder by the modified sol–gel combustion method

    Microsoft Academic Search

    Lin Yang; Tiecheng Lu; Hui Xu; Nian Wei

    2009-01-01

    Yttrium aluminum garnet (YAG) precursor was prepared by sol–gel combustion method using ethanol as solvent. Nano-sized YAG powders were obtained by precalcining the precursor at 500°C, and then calcining at different temperatures. The phase formation and characteristics of YAG powders were investigated by means of XRD, TG\\/DSC and TEM. Pure crystalline YAG phase was obtained at 800°C, without any intermediate