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1

Synthesis of cobalt aluminate nanopigments by a non-aqueous sol-gel route  

NASA Astrophysics Data System (ADS)

Here we report the chemical synthesis of cobalt aluminum oxide (CoAl2O4) nanoparticles by a non-aqueous sol-gel route. The one-pot procedure is carried out at mild temperatures (in the 150 to 300 °C range), and consists of the reaction between cobalt acetate and aluminium isopropoxide in benzyl alcohol. The resulting CoAl2O4 nanoparticles show an unusually low average size, between 2.5 and 6.2 nm, which can be controlled by the synthesis temperature. The colorimetric properties of the nanoparticles are also determined by the synthesis temperature and the characteristic blue color of CoAl2O4 pigments is achieved in samples prepared at T >= 200 °C. The nanoparticles are antiferromagnetically ordered below ~27 K with an uncompensated configuration. The uncompensated moment shows the typical features of strongly interacting superparamagnetic nanoparticles and spin-glass systems.Here we report the chemical synthesis of cobalt aluminum oxide (CoAl2O4) nanoparticles by a non-aqueous sol-gel route. The one-pot procedure is carried out at mild temperatures (in the 150 to 300 °C range), and consists of the reaction between cobalt acetate and aluminium isopropoxide in benzyl alcohol. The resulting CoAl2O4 nanoparticles show an unusually low average size, between 2.5 and 6.2 nm, which can be controlled by the synthesis temperature. The colorimetric properties of the nanoparticles are also determined by the synthesis temperature and the characteristic blue color of CoAl2O4 pigments is achieved in samples prepared at T >= 200 °C. The nanoparticles are antiferromagnetically ordered below ~27 K with an uncompensated configuration. The uncompensated moment shows the typical features of strongly interacting superparamagnetic nanoparticles and spin-glass systems. Electronic supplementary information (ESI) available: Further microscopy, diffraction, spectroscopy and thermal data. See DOI: 10.1039/c3nr34229h

Karmaoui, Mohamed; Silva, Nuno J. O.; Amaral, Vitor S.; Ibarra, Alfonso; Millán, Ángel; Palacio, Fernando

2013-05-01

2

Non-hydrolytic sol-gel routes to heterogeneous catalysts.  

PubMed

Oxides and mixed oxides have a tremendous importance in the field of heterogeneous catalysis, serving either as catalysts or as supports for active species. The performance of a catalyst depends directly on its composition, texture, structure and surface properties, which have to be precisely controlled and adapted to each application. In this context, the sol-gel process is a unique tool for the preparation and understanding of catalytic materials, owing to its exceptional versatility. In the last 10 years, the non-hydrolytic sol-gel (NHSG) or non-aqueous sol-gel process based on nonhydrolytic condensations in nonaqueous media has established itself as a simple and powerful method for the design of a wide range of oxide, mixed oxide and hybrid materials with controlled composition, morphology, texture and structure. NHSG proved particularly interesting for the preparation of catalytic materials, notably mesoporous xerogels, single site catalysts and highly crystalline nanoparticles. This critical review addresses the application of NHSG to the preparation of heterogeneous catalysts, emphasizing the specificities of this process, and giving a comprehensive overview of the literature (251 references). PMID:22377899

Debecker, Damien P; Mutin, P Hubert

2012-02-29

3

Synthesis of Carbon Nanotubes Using Sol Gel Route  

NASA Astrophysics Data System (ADS)

Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

Abdel-Fattah, Tarek

2002-12-01

4

Phase transition of Er 3+-doped Al 2O 3 powders prepared by the non-aqueous sol–gel method  

Microsoft Academic Search

The Er3+-doped Al2O3 powders have been prepared by the non-aqueous sol–gel method using the aluminum isopropoxide as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, and hydrated erbium nitrate, as dopant under isopropanol environment. The phase structure and phase transition of the Er3+-doped Al2O3 powders were investigated by using thermogravimetry\\/differential thermal analysis (TG\\/DTA), Fourier transform infrared spectroscopy (FT-IR), and

T. Yang; H. Wang; M. K. Lei

2006-01-01

5

AntiMicrobial Hydroxyapatite Particles Synthesized by a Sol–Gel Route  

Microsoft Academic Search

Sol–gel route was applied to synthesize anti-microbial hydroxyapatite (HAp) powders by the addition of silver 200–20000 ppm or zinc salts. The bacteria strain, Streptococcus mutans (S. mutans, ATCC 25175) was used in the anti-bacterial tests. HAp phase was reproducibly obtained by the preparation conditions: Ca(NO3)2-4H2O and trietheyl phosphate as sources of calcium and phosphorus sources, respectively, and ethanol as the

Ren-Jei Chung; Ming-Fa Hsieh; Kuo-Chang Huang; Li-Hsiang Perng; Fong-In Chou; Tsung-Shune Chin

2005-01-01

6

Raman study of nanosized titania prepared by sol–gel route  

Microsoft Academic Search

TiO2 polycrystalline powders have been prepared by different sol–gel routes and have been investigated by Raman spectroscopy and transmission electron microscopy. The influence of different catalysts on the crystalline phases obtained by thermal annealing is studied. The mechanisms that determine the Raman line shapes are discussed, including phonon confinement and pressure effects. The analysis of the Raman spectra, after thermal

Danilo Bersani; Giovanni Antonioli; Pier Paolo Lottici; Tessy Lopez

1998-01-01

7

Synthesis of alkoxide-derived V-Nb catalysts prepared by sol–gel route  

Microsoft Academic Search

Amorphous vanadium-niobium mixed oxides with high surface area have been prepared by sol–gel route starting from metal alkoxides using different H2O\\/V ratios. Dried samples have been characterized by XRD, atomic absorption and BET analysis. Calcination of dried materials up to 550°C in flowing air has been followed with TG–FT-IR spectroscopic analysis. Redox properties of calcined samples have been investigated with

M. Catauro; C. Pagliuca; L. Lisi; G. Ruoppolo

2002-01-01

8

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

SciTech Connect

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.

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

1998-11-23

9

New sol–gel synthetic route to transition and main-group metal oxide aerogels using inorganic salt precursors  

Microsoft Academic Search

We have developed a new sol–gel route to synthesize several different transition and main-group metal oxide aerogels. The approach is straightforward, inexpensive, versatile, and it produces monolithic microporous materials with high surface areas. Specifically, we report the use of epoxides as gelation agents for the sol–gel synthesis of chromia aerogels and xerogels from simple Cr(III) inorganic salts. The dependence of

Alexander E Gash; Thomas M Tillotson; Joe H Satcher Jr; Lawrence W Hrubesh; Randall L Simpson

2001-01-01

10

Intense up-conversion emissions of Yb3+/Dy3+ co-doped Al2O3 nanopowders prepared by non-aqueous sol—gel method  

NASA Astrophysics Data System (ADS)

Yb3+/Dy3+ co-doped Al2O3 nanopowders have been prepared by the non-aqueous sol—gel method and their up-conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4G9/2 ? 6H13/2, 4G9/2 ? 6H11/2, 4I15/2 ? 6H13/2, and 4F9/2 ? 6H11/2 transitions of Dy3+, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3+ and Dy3+ is discussed.

Li, Cheng-Ren; Li, Shu-Feng; Dong, Bin; Sun, Jing-Chang; Bo, Xiao-Feng; Fan, Xu-Nan

2012-09-01

11

Tailoring the dimensions of V2O5 nanoparticles by surfactant assisted non-aqueous sol-gel protocol and characterization  

NASA Astrophysics Data System (ADS)

Highly monodisperse vanadium pentoxide nanoparticles were synthesized by surfactant assisted non-aqueous sol-gel technique and followed by sintering at 300°C. From the powder XRD studies, as-prepared V2O5 show the average particle size between 25-50 nm and sintered sample in the range 35-75 nm. DRS UV-Vis spectroscopy and PL spectral studies reveal the optical direct band gap values between 2.5-2.7 eV and confirm the blue shift due to quantum confinement effect. HRSEM and HRTEM images of as-prepared sample show less fuzzy product due to the agglomeration with surfactant (PEG 400). But sintered sample images exactly illustrate particle size and its morphology. SAED pattern displays the (001) and (110) diffraction plane of orthorhombic crystalline phase.

Venkatesan, A.; Chandar, N. Krishna; Arjunan, S.; Kumar, R. Mohan; Jayavel, R.

2012-06-01

12

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

Microsoft Academic Search

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

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

2008-01-01

13

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

PubMed

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 transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. The results have proved that the nano-HAP powders synthesized by ultrasonic coupled sol-gel synthesis showed remarkable reduction in the particle size when compared with the conventional sol-gel method and hence these powders could be used as a coating material in biomedical applications. PMID:18356096

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

2008-02-14

14

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

Microsoft Academic Search

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

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

2008-01-01

15

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

PubMed Central

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.

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

2013-01-01

16

Tungsten Trioxide Films with Controlled Morphology and Strong Photocatalytic Activity via a Simple Sol–Gel Route  

Microsoft Academic Search

Novel nanostructured tungsten trioxide (WO3) films with strong photocatalytic activity, have been prepared by a simple sol–gel route from aqueous peroxopolytungstic\\u000a acid (PTA) precursor solutions. We demonstrate that films with different morphologies can be synthesized by simply adjusting\\u000a the pH of this precursor solution using different mineral acids such as HCl and HC1O4, and that this control of film texture

Bin Yang; Piers R. F. Barnes; Yingjie Zhang; Vittorio Luca

2007-01-01

17

Infrared-to-visible CW frequency upconversion in erbium activated silica–hafnia waveguides prepared by sol–gel route  

Microsoft Academic Search

70SiO2–30HfO2 mol% planar waveguides, doped with Er3+ with concentrations ranging from 0.3 to 2 mol% were prepared by sol–gel route, using dip-coating deposition on vitreous-SiO2 substrates. Infrared-to-visible upconversion emission, upon excitation at 980 nm, has been observed for all the samples. The upconversion results in green, red and blue emissions. The investigation of the upconversion dynamic as a function of

Rogéria R. Gonçalves; Giovanni Carturan; Luca Zampedri; Maurizio Ferrari; Alessandro Chiasera; Maurizio Montagna; Giancarlo C. Righini; Stefano Pelli; Sidney J. L. Ribeiro; Younes Messaddeq

2003-01-01

18

Synthesis and Characterization of Oxide Dispersion Strengthened Ferritic Steel via a Sol-Gel Route  

NASA Astrophysics Data System (ADS)

Nanocrystalline oxide dispersion strengthened (ODS) ferritic steel powders with nominal composition of Fe-14Cr-3W-0.3Ti-0.4Y2O3 are synthesized using sol-gel method and hydrogen reduction. At low reduction temperature the impurity phase of CrO is detected. At higher reduction temperature the impurity phase is Cr2O3 which eventually disappears with increasing reduction time. A pure ODS ferritic steel phase is obtained after reducing the sol-gel resultant products at 1200°C for 3 h. The HRTEM and EDS mapping indicate that the Y2O3 particles with a size of about 15 nm are homogenously dispersed in the alloy matrix. The bulk ODS ferritic steel samples prepared from such powders exhibit good mechanical performance with an ultimate tensile stress of 960 MPa.

Sun, Qinxing; Zhang, Tao; Wang, Xianping; Fang, Qianfeng; Hu, Jing; Liu, Changsong

2012-07-01

19

Ferroelectric properties of tungsten-doped bismuth titanate thin film prepared by sol–gel route  

Microsoft Academic Search

Ferroelectric properties of W-doped Bi4Ti3O12 (W-BIT) thin film were investigated in comparison with those of undoped Bi4Ti3O12 (BIT), which were prepared by sol–gel method and spin-coating technique. X-ray diffraction (XRD) measurements showed layered perovskite structures with a single phase in both films. The W-BIT film appeared to have superior ferroelectric properties to the undoped film prepared under the same conditions.

Jong Kuk Kim; Tae Keon Song; Sang Su Kim; Jinheung Kim

2002-01-01

20

The nanoparticle-coating process: a potential sol-gel route to homogeneous nanocomposites  

Microsoft Academic Search

A sol-gel process was developed for fabricating inherently homogeneous nanocomposites involving: (a) precipitation of nanoparticles; (b) coating the nanoparticles with a film of matrix phase, and; (c) powder forming and sintering. Die-pressed ZrO2(nanoparticle)–glass(matrix) specimens were pressureless sintered at 1100°C. Scanning electron microscopy (SEM) of these partially sintered specimens revealed a uniform arrangement of nanopores (?10?8 m), suggesting homogeneous ZrO2 nanoparticle

Andrew J. Ruys; Yiu-Wing Mai

1999-01-01

21

New sol-gel synthetic route to transition and main-group metal oxide aerogels using inorganic salt precursors  

SciTech Connect

We have developed a new sol-gel route to synthesize several transition and main-group metal oxide aerogels. The approach is straightforward, inexpensive, versatile, and it produces monolithic microporous materials with high surface areas. Specifically, we report the use of epoxides as gelation agents for the sol-gel synthesis of chromia aerogels and xerogels from simple Cr(III) inorganic salts. The dependence of both gel formation and its rate was studied by varying the solvent used, the Cr(III) precursor salt, the epoxide/Cr(III) ratio, as well as the type of epoxide employed. All of these variables were shown to affect the rate of gel formation and provide a convenient control of this parameter. Dried chromia aerogels were characterized by high-resolution transmission electron microscopy (HRTEM) and nitrogen adsorption/desorption analyses, results of which will be presented. Our studies have shown that rigid monolithic gels can be prepared from many different metal ions salts, provided the formal oxidation state of the metal ion is greater than or equal to +3. Conversely, when di-valent transition metal salts are used precipitated solids are the products.

Gash, A E; Tillotson, T M; Satcher Jr, J H; Hrubesh, L W; Simpson, R L

2000-09-12

22

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

SciTech Connect

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.

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

23

Physical and optical properties of CuBO2 nanopowders synthesized via sol-gel route  

NASA Astrophysics Data System (ADS)

As a new candidate in the p-type TCOs group, CuBO2 has been under research spotlight in very recent years. The present work describes a new cost effective sol-gel technique to synthesize the CuBO2 nanopowders and structural properties of the same were examined by X-ray powder diffraction studies. The particle size and other morphological information were obtained from field emission scanning electron microscope and transmission electron microscope. The compositional analysis was performed using energy dispersive analysis of X-ray. The transmittance spectra and hence the band gap of the as-synthesized CuBO2 nanopowder was obtained by a UV-visible near infrared spectrophotometer. The photoluminescence property of this material is reported here for the first time and the material showed efficient photoluminescence with the appearance of a broad peak at 370 nm. The broad band can be deconvoluted and the different peaks were assigned to band to band transition and electron transition in Cu+ ions under the excitation, i.e. 3d94s1-3d10.

Santra, S.; Das, N. S.; Chattopadhyay, K. K.

2012-10-01

24

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

SciTech Connect

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.

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

2005-02-11

25

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

NASA Astrophysics Data System (ADS)

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.

Wei, Qiong; Chen, Donghua

2010-10-01

26

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

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

Albin Pintar; Jurka Batista; Stanko Ho?evar

2005-01-01

27

A sol-gel route to prepare Tl-Ca-Ba-Cu-O superconductor with Tc above 120 K  

NASA Astrophysics Data System (ADS)

The preparation of Tl-Ca-Ba-Cu-O superconductor with Tc above 120 K from Ca-Ba-Cu-O precursor mixed with thallium oxide was obtained. The Ca-Ba-Cu-O precursor was prepared by sol-gel method from the proper complexation and polymerzation of the metal nitrates by citric acid and ethylene diamine. The excellent homogeneity and small particle size make the sol-gel precursor a potential candidate for Tl-Ca-Ba-Cu-O film preparation by screen-printing or spin-coating and thallium vapor diffusion.

Liu, R. S.; Wang, W. N.; Wu, P. T.; Chang, C. T.

1989-12-01

28

Aqueous sol-gel routes to conducting films of indium oxide and indium-tin-oxide  

NASA Astrophysics Data System (ADS)

Thin films of indium tin oxide (ITO) are of interest because of their high transparency and low electrical resistivity. Applications include use as electrodes for liquid crystal display and as heat mirrors for solar energy devices. We have developed totally aqueous routes to indium oxide (IO) and ITO materials because, (1) the particulate sols afford a longer shelf life than for alkoxyide derived materials, (2) organics do not have to be removed from the films by baking, and (3) the starting materials are cheaper than the corresponding alkoxides. Indium and mixed indium/tin sols have been prepared form inorganic solutions and treated with alkali to produce white thixotropic sols ca. 0.64 in Mz+ ions. This films were prepared by spinning on low iron or pure silica slides previously cleaned with DECON and washed with distilled water. Films were subsequently heated at 773K in air, or 1173K in air or nitrogen. The film with the lowest resistivity contained ca. 5 percent Sn and had an average optical transmittance between 400 and 600nm of 95 percent. The film was non-porous, smooth in texture, approximately 300nm thick and had a band gap energy of 3.22eV.

Perry, Carole C.; McGiveron, J. K.; Harrison, Philip G.

2000-05-01

29

Density fractionated hollow silica microspheres with high-yield by non-polymeric sol–gel\\/emulsion route  

Microsoft Academic Search

Hollow silica microspheres were synthesized by non-polymeric sol–gel\\/emulsion technique using tetra ethyl orthosilicate (TEOS) as a source of silica. A sol mixture of TEOS, water, ethanol and acid was emulsified in a solution of light paraffin oil and surfactant (Span-80). Calcined spheres were density fractionated between density ranges: 1.74gcm?3. The samples were characterized by optical and scanning electron microscopy with

R. K. Singh; A. Garg; R. Bandyopadhyaya; B. K. Mishra

2007-01-01

30

Bioactive materials for biomedical applications using sol-gel technology.  

PubMed

This review paper focuses on the sol-gel technology that has been applied in many of the potential research areas and highlights the importance of sol-gel technology for preparing bioactive materials for biomedical applications. The versatility of sol-gel chemistry enables us to manipulate the characteristics of material required for particular applications. Sol-gel derived materials have proved to be good biomaterials for coating films and for the construction of super-paramagnetic nanoparticles, bioactive glasses and fiberoptic applicators for various biomedical applications. The introduction of the sol-gel route in a conventional method of preparing implants improves the mechanical strength, biocompatibility and bioactivity of scaffolds and prevents corrosion of metallic implants. The use of organically modified silanes (ORMOSILS) yields flexible and bioactive materials for soft and hard tissue replacement. A novel approach of nitric-oxide-releasing sol-gels as antibacterial coatings for reducing the infection around orthopedic implants has also been discussed. PMID:18689920

Gupta, Radha; Kumar, Ashok

2008-08-08

31

Controlled synthesis of highly ordered LaFeO{sub 3} nanowires using a citrate-based sol-gel route  

SciTech Connect

Highly ordered LaFeO{sub 3} nanowires of complex oxide were controlled synthesized with a porous anodic aluminum oxide (AAO) template by a citrate-based sol-gel route. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the LaFeO{sub 3} nanowires formed a uniform length and diameter, which were determined by the thickness and the pore diameter of the AAO template, respectively. The results of X-ray diffraction (XRD) and the selected area electron diffraction (SAED) indicated that the LaFeO{sub 3} nanowires had a perovskite-type crystal structure. Furthermore, X-ray photoelectron spectroscopy (XPS) demonstrated that stoichiometric LaFeO{sub 3} was formed.

Yang Zhi [College of Chemistry and Chemical Engineering, Lanzhou University, Gansu, Lanzhou 730000 (China); Huang Yi [College of Chemistry and Chemical Engineering, Lanzhou University, Gansu, Lanzhou 730000 (China); Dong Bin [College of Chemistry and Chemical Engineering, Lanzhou University, Gansu, Lanzhou 730000 (China); Li Hulin [College of Chemistry and Chemical Engineering, Lanzhou University, Gansu, Lanzhou 730000 (China)]. E-mail: lihl@lzu.edu.cn

2006-02-02

32

Role of the surface polarity in governing the luminescence properties of ZnO nanoparticles synthesized by Sol-gel route  

NASA Astrophysics Data System (ADS)

ZnO nanoparticle samples, which are synthesized by a sol-gel route and collected after various stages of a washing procedure, are systematically investigated using a variety of experimental techniques. The study shows that while the surface charge polarity is positive for the as-grown (unwashed) particles, the surface turns negatively charged when the particles are sufficiently washed. This dissimilar surface charge polarity has been found to result in markedly different luminescence characteristics for the two cases (washed and unwashed). Our study of the luminescence properties under different surrounding conditions furthermore reveals that the major source for the GL emission for these nanoparticles is the hydroxyl groups, which are physisorbed on the surface.

Sharma, A.; Dhar, S.; Singh, B. P.

2013-05-01

33

A Sol-Gel Route for the Synthesis of Bi2Ru2O7 Pyrochlore Oxide for Oxygen Reaction in Alkaline Medium  

NASA Astrophysics Data System (ADS)

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.

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

2001-11-01

34

Homoleptic gallium(III) and indium(III) aminoalkoxides as precursors for sol-gel routes to metal oxide nanomaterials.  

PubMed

New homoleptic aminoalkoxides of gallium(III) and indium(III) of the types M4{(OC2H4)2NMe}6 [M = Ga (1), In (2)] and [Ga{(OC2H4)3N}]n (3), as well as a previously described Ga2(OC2H4NMe2)6 (A) have been prepared by isopropoxo(chloro)-aminoalkoxo exchange reactions and characterised by elemental analyses, FT-IR and 1H NMR spectroscopy. Formation of a star-shaped Ga[Ga{mu-eta3:eta1-(OC2H4)2NMe}2]3 (1.4CHCl3) and a zigzag linear In4{mu-eta3:eta1-(OC2H4)2NMe}6 (2.6CHCl3), as revealed by X-ray single crystal structures, reflects the structural diversity among N-methyldiethanolaminate derivatives. Their hydrolyses in boiling water, either in presence or absence of tetraalkylamonium bromide, have been studied and, for gallium derivatives, compared with similar hydrolytic reactions of Ga(OiPr)3. The hydrolysed products were studied by FT-IR, TG-DTA and XRD techniques. For gallium derivatives, transition from orthorhombic Ga(O)OH phase of as-prepared powder to phase pure rhombohedral- and monoclinic-Ga2O3 occurred at about 500 degrees C and 700 degrees C, respectively, whereas cubic In(OH)3 phase of as-prepared powder of 2 was converted to cubic In2O3 at 250 degrees C. Partial hydrolyses were also performed and evolution of the particle size in solution was recorded by light scattering measurements. Various sol-gel processing parameters such as concentration and hydrolysis ratio (h) were studied in order to stabilise nano-sized colloidal suspensions for access to thin films by spin coating. The N-methyldiethanolamine derivatives 1 and 2 were found to be the most suitable candidates for sol-gel processing. The transparent Ga2O3 and In2O3 films obtained on glass or Si wafers from spin-coating of 1 and 2, respectively, were characterised by SEM, EDX and XRD. PMID:19319402

Mishra, Shashank; Daniele, Stéphane; Petit, Sarah; Jeanneau, Erwann; Rolland, Marc

2009-02-13

35

Structural, optical and morphological analyses of pristine titanium di-oxide nanoparticles - Synthesized via sol-gel route.  

PubMed

Pure titanium di-oxide nanoparticles (TiO2) were synthesized by sol-gel technique at room temperature with appropriate reactants. The synthesis of anatase phase TiO2 nanoparticles was achieved by tetraisopropyl orthotitanate and 2-propanol as common starting materials and the product was annealed at 450°C for 4h. The synthesized product was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-VIS-Diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy and Scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX) analysis. XRD pattern confirmed the crystalline nature and tetragonal structure of synthesized composition. Average grain size was determined from X-ray line broadening, using the Debye-Scherrer relation. The functional groups present in the sample were identified by FTIR spectroscopy. Diffuse reflectance measurement indicated an absorption band edge on UV-region. The allowed direct and indirect band gap energies, as well as the crystallite size of pure TiO2 nanoparticles are calculated from DRS analysis. The microstructure and elemental identification were done by SEM with EDX analysis. PMID:24113014

Praveen, P; Viruthagiri, G; Mugundan, S; Shanmugam, N

2013-09-19

36

Coupling sol-gel synthesis and microwave-assisted techniques: a new route from amorphous to crystalline high-surface-area aluminium fluoride.  

PubMed

A non-aqueous sol-gel Al-based fluoride has been subjected to the microwave solvothermal process. The final material depends on the temperature heat treatment used. Three types of material have been prepared: 1) for low temperature heat treatment (90 degrees C) X-ray amorphous alkoxy fluoride was obtained; 2) for the highest temperature used (200 degrees C) the metastable form beta-AlF3 was obtained with a very large surface area of 125 m2 g(-1). The mechanism of the amorphous=crystalline transformation has been rationalised by the occurrence of a decomposition reaction of the gel fluoride induced by the microwave irradiation. 3) Finally, at intermediate temperature (180 degrees C) a multi-component material mixture exhibiting a huge surface area of 525 m2 g(-1) has been obtained and further investigated after mild post-treatment fluorination using F2 gas. The resulting aluminium-based fluoride still possesses a high-surface-area of 330 m2 g(-1). HRTEM revealed that the solid is built from large particles (50 nm) identified as alpha-AlF3, and small ones (10 nm), relative to an unidentified phase. This new high-surface-area material exhibits strong Lewis acidity as revealed by pyridine adsorption and catalytic tests. By comparison with other materials, it has been shown that whatever the composition/structure of the Al-based fluoride materials, the number of strong Lewis acid sites is related to the surface area, highlighting the role of surface reconstruction occurring on a nanoscopic scale on the formation of the strongest Lewis acid sites. PMID:18491305

Dambournet, Damien; Eltanamy, Gehan; Vimont, Alexandre; Lavalley, Jean-Claude; Goupil, Jean-Michel; Demourgues, Alain; Durand, Etienne; Majimel, Jérôme; Rudiger, Stephan; Kemnitz, Erhard; Winfield, John M; Tressaud, Alain

2008-01-01

37

Magnetic, electrical, and microstructural properties of YBa2Cu3O7 - A comparison of sol-gel, co-precipitated, and solid state processing routes  

NASA Astrophysics Data System (ADS)

Samples of YBa2Cu3O7 were prepared by sol-gel, co-precipitation, and solid state processes. Sol-gel samples were prepared from a solution of yttrium, barium, and copper nitrates dissolved in ethylene glycol, co-precipitated samples were made by the amorphous citrate method, and solid state samples were prepared by conventional high temperature reaction of the appropriate metal oxides and carbonates. The sol-gel process was shown to yield superconducting samples of superior Meissner effect, critical current, and critical field. The co-precipitated samples contain impurities that affect the critical properties. The sol-gel and co-precipitated processes yield materials with well-formed, plate-like particles with a fairly uniform size of about 10 microns. The grains in the solid state sample are smaller but have a much wider distribution of sizes than the samples prepared by solution methods.

Hayri, E. A.; Greenblatt, M.; Ramanujachary, K. V.; Nagano, M.; Oliver, J.

1989-10-01

38

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

NASA Astrophysics Data System (ADS)

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.

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

39

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)

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.

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

2011-11-01

40

Crystallization behaviors and electric properties of (Pb0.8Ca0.2)TiO3 thin films prepared by a sol-gel route  

NASA Astrophysics Data System (ADS)

The pure tetragonal perovskite (Pb0.8Ca0.2)TiO3 (PCT) thin films deposited on (1 1 1)Pt/Ti/SiO2/Si substrate were successfully achieved by a sol-gel route, and the influence of pyrolysis temperature on crystallization behaviors and electric properties of the PCT films was investigated. It was found that the film pyrolyzed at 450 °C could be crystallized at temperature as low as 450 °C, while the film pyrolyzed at 350 °C is amorphous under the same crystallization temperature. It was also found that the PCT films pyrolyzed at different temperatures could be fully crystallized when the crystallization temperature was raised to 600 °C, and compared to the film pyrolyzed at 350 °C, the film pyrolyzed at 450 °C exhibited higher (1 0 0) orientation and possessed enhanced electric properties (remanent polarization ˜19.5 ?C/cm2, piezoelectric constant ˜125 pm/v, pyroelectric coefficient ˜310 ?C/m2K).

Chi, Q. G.; Zhu, H. F.; Lin, J. Q.; Chen, C. T.; Wang, X.; Chen, Y.; Lei, Q. Q.

2013-05-01

41

Thickness effect on electrical properties of Pb(Zr 0.52Ti 0.48)O 3 thick films embedded with ZnO nanowhiskers prepared by a hybrid sol–gel route  

Microsoft Academic Search

Silicon-based lead zirconate titanate thick films embedded with zinc oxide nanowhiskers (ZnOw–PZT) were prepared by a hybrid sol–gel route. ZnOw–PZT films with thickness from 1.5?m to 4?m are perovskite structure and have smooth surface without any cracks. As the thickness increases, the remanent polarization and dielectric constant increase, but the coercive field and tetragonality decrease. Compared with PZT films, the

Q. L. Zhao; M. S. Cao; J. Yuan; R. Lu; D. W. Wang; D. Q. Zhang

2010-01-01

42

The Microscopic Magnetic Properties of W-type Hexaferrite Powder Prepared by A Sol-Gel Route  

Microsoft Academic Search

Magnetic particles of W-type barium-calcium hexaferrite (BaCa2Fe16O27) have been synthesized using a Stearic acid gel route. The gel precursors were dried at 100° C for 2 hrs and then calcinated at 650° C, 750° C, 850° C and 950° C for 4 hrs in a furnace and slowly cooled to room temperature in order to obtain barium-calcium hexaferrite particles. The

Rajshree Jotania; Chetna Chauhan; Pooja Sharma

2010-01-01

43

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

PubMed

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

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

2013-04-01

44

The Microscopic Magnetic Properties of W-type Hexaferrite Powder Prepared by A Sol-Gel Route  

SciTech Connect

Magnetic particles of W-type barium-calcium hexaferrite (BaCa{sub 2}Fe{sub 16}O{sub 27}) have been synthesized using a Stearic acid gel route. The gel precursors were dried at 100 deg. C for 2 hrs and then calcinated at 650 deg. C, 750 deg. C, 850 deg. C and 950 deg. C for 4 hrs in a furnace and slowly cooled to room temperature in order to obtain barium-calcium hexaferrite particles. The microscopic magnetic properties of prepared samples studying using Moessbauer spectroscopy. Moessbauer spectra of all samples were recorded at room temperature. Mossbauer parameters like Isomer shift, Quadruple splitting etc. were calculated with respect to iron foil. Barium calcium hexaferrite samples heated at 650 deg. C, 750 deg. C, 850 deg. C show relaxation type Moessbauer spectra along with paramagnetic doublet. The intensity of paramagnetic doublet increases with temperature confirm the presence of ferrous ions in the samples, where as sample calcinated at 950 deg. C confirm the presence of ferrimagnetic phase with partial super paramagnetic nature of prepared hexaferrite sample.

Jotania, Rajshree; Chauhan, Chetna [Material Science Research Laboratory, Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380 009 (India); Sharma, Pooja [Department of Physics, Saurashtra University, Rajkot 360 005 (India)

2010-12-01

45

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

Microsoft Academic Search

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

A. Pradeep; P. Priyadharsini; G. Chandrasekaran

2008-01-01

46

A sol–gel route using propylene oxide as a gelation agent to synthesize spherical NiAl 2O 4 nanoparticles  

Microsoft Academic Search

Spherical NiAl2O4 nanoparticles with large surface area were successfully synthesized by a sol–gel method using propylene oxide as a gelation agent. The formation process of the resulting nanoparticles is described and characterized by TG-DTA, XRD, BET and TEM. A pseudo-spinel structure was formed at 700°C and a spinel NiAl2O4 structure was formed at 800°C by the reaction of NiO at

Hongtao Cui; Marcos Zayat; David Levy

2005-01-01

47

An easy sol–gel route for deposition of oriented Ln 2Ti 2O 7 (Ln=La, Nd) films on SrTiO 3 substrates  

Microsoft Academic Search

The effect of the orientation of SrTiO3 (STO) substrates, (100) or (110), on the growth of La2Ti2O7 (LTO) and Nd2Ti2O7 (NTO) thin films was investigated. The films were deposited via a sol–gel process coupled to the spin-coating technique. Depending on the substrate orientation, a similar effect was observed on the structural properties for both the LTO and NTO thin films.

Zhenmian Shao; Sébastien Saitzek; Pascal Roussel; Marielle Huvé; Rachel Desfeux; Olivier Mentré; Francis Abraham

2009-01-01

48

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

Microsoft Academic Search

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%

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

2011-01-01

49

Effect of curing process on simulated antisoiling properties of sol–gel coating on pine sapwood  

Microsoft Academic Search

Recently, inorganic–organic hybrid coatings produced by the sol–gel route have proven to be a potential protective treatment\\u000a for wooden surfaces. In this study, the effect of curing process on simulated antisoiling properties of sol–gel coating was\\u000a investigated. The sol–gel coating was spray-coated on pine sapwood and cured with different temperature and time combinations.\\u000a The antisoiling properties were studied by measuring

Juha Nikkola; Riitta Mahlberg; Juha Mannila; Saila Jämsä

2010-01-01

50

Morphology and optical properties of a porous silicon-doped sol-gel host  

NASA Astrophysics Data System (ADS)

Porous silicon (PSi) fabricated by a chemical route was successfully separated in 1,4-dioxane and then incorporated in a sol-gel host. The properties of PSi in both solution and a sol-gel environment were investigated using optical techniques, and strong luminescence was observed. The morphology of PSi was similar in solution and the sol-gel, with particles positioned close together. The PSi samples were highly crystalline. Transmission electron microscopy of PSi in solution revealed that the particles were monodisperse and roughly spherical in shape, with a diameter of around 5 nm. The effect of embedding PSi in a sol-gel matrix on its optical properties was investigated. Changes in the photoluminescence peaks of PSi during the phase transition from sol to dried gel were observed. PSi exhibited good photoluminescence stability in the sol-gel matrix, and crack-free sol-gel rods were obtained.

Khan, M. Naziruddin; Al Dwayyan, A. S.; Al Hoshan, M.

2013-09-01

51

Acetone gas-sensing performance of Sr-doped nanostructured LaFeO 3 semiconductor prepared by citrate sol–gel route  

Microsoft Academic Search

Nanocrystalline La1?xSrxFeO3 (x = 0, 0.1, 0.2, 0.3 and 0.4) was prepared by sol–gel citrate method. The structural and microstructural characterization has been carried out with the help of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD studies confirm the formation of LaFeO3 with perovskite phase. Further studies by Fourier transform infrared spectroscopy were also conducted. DC electrical properties of

P. A. Murade; V. S. Sangawar; G. N. Chaudhari; V. D. Kapse; A. U. Bajpeyee

2011-01-01

52

Effect of acetylacetone on the preparation of PZT materials in sol–gel processing  

Microsoft Academic Search

Sol–gel processing is an advantageous route to produce PZT thin film materials with high quality. PZT powders and thin films with good properties were fabricated by sol–gel processing, using acetylacetone as modifier, in the study. The morphologies of PZT powders and thin films were observed by field emission microscopy, and the dielectric and properties of the PZT thin films were

Luqian Weng; Xujin Bao; Kwesi Sagoe-Crentsil

2002-01-01

53

Synthesis of YBa2Cu3O7-x by sol-gel route formation of YBaCuO oxycarbonate intermediate  

NASA Astrophysics Data System (ADS)

High-Tc superconducting powders of the Y-Ba-Cu-O system are prepared by a solution-polyacrylamide gel using citric acid as a complexing agent. This method provides an easy way to prepare reactive YBaCuO powders. However, sol-gel synthesis of this oxide involves the formation of intermediate phases which impedes the obtaining of the pure phase at low temperature. An intermediate oxycarbonate phase forms between 800 and 850°C in flowing oxygen. From powder X-ray diffraction, thermal analysis and IR spectroscopy, it is concluded that the intermediate oxycarbonate has an average tetragonal structure - SG P4/ mmm - similar to the parent oxide with a stoichiometry close to YBa2Cu2.95(CO3)0.35O6.6. The carbonate group is located in the center of the basal CuO square. This compound has superconducting properties. A pure 123 phase is obtained when the sol-gel precursor is annealed at 925°C in O2.

Gotor, F. J.; Odier, P.; Gervais, M.; Choisnet, J.; Monod, Ph.

1993-12-01

54

Sol-gel processing of a bimetallic alkoxide precursor confined in a porous glass matrix: a route to novel glass/metal oxide nanocomposites.  

PubMed

In this work we present the utilization of the heterometallic alkoxide [FeCl{Ti(2)(OPr(i))(9)}] as the first sol-gel single-source precursor to achieve nanocomposites made of iron and titanium oxides incorporated into Porous Vycor Glass (PVG). The nanocomposites were prepared by the impregnation of the precursor in a PVG plate followed by hydrolysis reactions. Different samples were obtained by further thermal treatment of the hydrolyzed sample. The nanocomposites were characterized by UV-vis-NIR, Raman and EPR spectroscopies, XRD and TEM. The results indicate that the room-temperature hydrolyzed samples are formed by nanoparticles of FeOOH and brookite-TiO(2) embedded on a glassy matrix. After the heat treatment at temperatures above 900 degrees C, a pseudobrookite Fe(2)TiO(5) was formed. All samples present high transparency and homogeneity. The results showed here indicate that the sol-gel process using the single-source precursor [FeCl{Ti(2)(OPr(i))(9)}] should be a novel and efficient approach to the preparation of nanometric Fe/Ti oxides incorporated into a glassy matrix. PMID:16494894

Menezes, Willian G; Camargo, Pedro H C; Oliveira, Marcela M; Evans, David J; Soares, Jaísa F; Zarbin, Aldo J G

2006-02-21

55

Invited review “sol-gel” preparation of high temperature superconducting oxides  

Microsoft Academic Search

This review article focuses on the sol-gel preparation of high temperature superconducting oxides wherein different classes of gel technologies were utilized. These involve: 1) the sol-gel route based upon hydrolysis-condensation of metal-alkoxides, 2) the gelation route based upon concentration of aqueous solutions involving metal-chelates, often called as “chelate gel” or “amorphous chelate” route, and 3) the organic polymeric gel route.

Masato Kakihana

1996-01-01

56

Sol-gel processing of NASICON thin-film precursors  

Microsoft Academic Search

Metal-alkoxides have been used to produce Nasicon solid electrolyte thin-film precursors via sol-gel processing route. The influence of various processing parameters e.g., solvent type, temperature, acid or base catalysts, pH, chelating agents, etc., on the hydrolysis-polycondensation (gelation) behaviour of the metal-alkoxides is discussed.

A. Ahmad; C. Glasgow; T. A. Wheat

1995-01-01

57

Photobleaching in Y3Al5O12:Ce3+ macroporous monoliths prepared via sol - gel route accompanied by phase separation  

NASA Astrophysics Data System (ADS)

Macroporous Y3Al5O12 doped with Ce3+ (YAG:Ce) ceramics has been prepared using the metal salt-derived sol-gel processing followed by the heat treatment at temperatures of 800 to 1500 °C. The obtained YAG:Ce crystal exhibits a broad emission band around 530 nm ascribable to 5d-4f transitions of Ce3+. Irradiation of the samples with an intense laser light from a He-Cd laser (wavelength = 442 nm) leads to a decrease in the fluorescence intensity, indicating the occurrence of photoionization of Ce3+ and subsequent capture of excited electrons by some trapping sites. It is found that the rate of the photobleaching decreases with an increase in size of YAG crystallites, depending on the temperature of heat treatment; photobleaching takes place more rapidly when heat treatment is performed at lower temperatures, while the heat treatment at higher temperatures suppresses the bleaching.

Iwata, Koji; Fujita, Koji; Murai, Shunsuke; Tanaka, Katsuhisa

2011-02-01

58

Molecular imprinting in sol-gel matrix.  

PubMed

Molecular imprinting is a newly developed methodology which provides molecular assemblies of desired structures and properties and is being increasingly used for several applications such as in separation processes, microreactors, immunoassays and antibody mimics, catalysis, artificial enzymes, biosensor recognition elements and bio- and chemo-sensors. The ambient processing conditions and versatility of the sol-gel process makes sol-gel glassy matrix suitable for molecular imprinting. The progress of sol-gel based molecular imprinted polymers (MIPs) for various applications can be seen from the growing number of publications. The main focus of the review is molecular imprinting in sol-gel matrix and applications of molecular imprinted sol-gel derived materials for the development of sensors. Combining sol-gel process with molecular imprinting enables to procure the sensors with greater sensitivity and selectivity necessary for sensing applications. The merits, problems, challenges and factors affecting molecular imprinting in sol-gel matrix have been discussed. Considerable attention has been drawn on recent developments like use of organically modified silane precursors (ORMOSILS) for the synthesis of hybrid molecular imprinted polymers (HMIPs) and applying surface sol-gel process for molecular imprinting. The development of molecular imprinted sol-gel nanotubes for biochemical separation and bio-imprinting is a new advancement and is under progress. Templated xerogels and molecularly imprinted sol-gel films provide a good platform for various sensor applications. PMID:18692561

Gupta, Radha; Kumar, Ashok

2008-07-19

59

Fabrication of molecularly imprinted hybrid monoliths via a room temperature ionic liquid-mediated nonhydrolytic sol-gel route for chiral separation of zolmitriptan by capillary electrochromatography.  

PubMed

A room temperature ionic liquid (RTIL)-mediated nonhydrolytic sol-gel (NHSG) protocol was explored for the fabrication of new molecularly imprinted silica-based hybrid monoliths for chiral separation of a basic template zolmitriptan by CEC. The RTIL-mediated NHSG protocol involved free-radical copolymerization and NHSG process. Three carboxylic acids (trifluoromethyl acrylic acid, cinnamic acid, and methacrylic acid (MAA)) were examined as both the functional monomers and the catalysts for the NHSG condensation of methacryloxypropyltrimethoxysilane (MPTMS) to form silica-based framework. RTIL was incorporated to reduce gel shrinkage and also to act as the pore template. The effects of carboxylic acids and RTIL on the performance of the silica-based hybrid molecularly imprinted polymer (MIP) monoliths were investigated in detail to realize excellent chiral recognition and to give new insights into the mechanism of the RTIL-mediated NHSG strategy. Excellent chiral separation of (R)/(S)-zolmitriptan was achieved when the molar ratio of MAA to MPTMS was 1:4 and 1:2 with RTIL involved. The synergism of the free-radical copolymerization of the C=C bond of carboxylic acids and MPTMS with the NHSG condensation of MPTMS catalyzed by the carboxylic acids was demonstrated. The incorporation of RTIL increased porosity, and hence improved selectivity of the prepared hybrid monoliths. PMID:18203253

Wang, He-Fang; Zhu, Yi-Zhou; Lin, Jian-Ping; Yan, Xiu-Ping

2008-02-01

60

Densely packed single-crystal Bi{sub 2}Fe{sub 4}O{sub 9} nanowires fabricated from a template-induced sol-gel route  

SciTech Connect

Densely packed single-crystal Bi{sub 2}Fe{sub 4}O{sub 9} nanowires were successfully synthesized by a template-induced citrate-based sol-gel process. The structural properties of the nanowires were characterized using many techniques. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that Bi{sub 2}Fe{sub 4}O{sub 9} nanowires possessed a uniform length and diameter, which were controlled by the thickness and the pore diameter of the applied porous anodic aluminum oxide (AAO) template, respectively. The results of X-ray diffraction (XRD) and the selected area electron diffraction (SAED) indicated that Bi{sub 2}Fe{sub 4}O{sub 9} nanowires had an orthorhombic single-crystal structure. Furthermore, the energy-dispersive X-ray (EDX) spectroscopy demonstrated that the stoichiometric Bi{sub 2}Fe{sub 4}O{sub 9} was formed. The possible formation mechanism of nanowires was also discussed. - Graphical abstract: The top view in low magnification of SEM images of Bi{sub 2}Fe{sub 4}O{sub 9} nanowires after AAO template is partly dissolved.

Yang Zhi [Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Huang Yi [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Dong Bin [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Li Hulin [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Shi Sanqiang [Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)]. E-mail: mmsqshi@polyu.edu.hk

2006-11-15

61

Structural and magnetic properties of BaCoxZrxFe(12-2x)O19 prepared by citrate precursor sol-gel route  

NASA Astrophysics Data System (ADS)

The aim of this work is to investigate the correlation between the distribution of cations over five crystallographic positions and magnetic properties of Ba-hexaferrites in the coupled substitution of magnetic Co2+ and non-magnetic Zr4+ for Fe3+. We have accomplished the synthesis of Co-Zr doped BaCoxZrxFe(12-2xO19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) by citrate precursor sol-gel method under acidic conditions. Single phase M-type hexagonal ferrites are formed at 800 °C. The average size of hexagonal platelets is 34 nm. Mössbauer analysis suggests that site preferences depend upon the concentration of dopants. Dopant ions prefer 4f2 site at x = 0.4 while 12k site is largely substituted at higher dopant concentrations. Magnetic hysteresis data show that the coercive force is markedly reduced with increasing Co-Zr contents but net magnetization and coercivity are not correlated with dopant levels [MS = 61.02 emu/g, HC = 2790 Oe (x = 0); MS = 61.31 emu/g, HC = 100 Oe (x = 0.4); MS = 49.34, HC = 2134 Oe (x = 0.6); MS = 54.94 emu/g, HC = 1443 Oe (x = 1.0)]. Our results show that the magnetization and magnetocrystalline anisotropy are closely related to the distribution of Co-Zr on the five sites.

Chawla, S. K.; Mudsainiyan, R. K.; Meena, S. S.; Yusuf, S. M.

2013-06-01

62

Sol-gel coating on acoustic wave devices: Thin film characterization and chemical sensor development.  

National Technical Information Service (NTIS)

We have investigated the use of porous oxide coatings, formed using sol-gel chemistry routes, as the discriminating elements of acoustic wave (AW) chemical sensors. These coatings provide several unique advantages: durability, high adsorption capacity bas...

G. G. Frye C. J. Brinker A. J. Ricco S. J. martin J. Hilliard

1990-01-01

63

Sol–gel materials for electrochemical biosensors  

Microsoft Academic Search

An overview is presented of the state-of-the art of electrochemical biosensors employing sol–gel materials. Low-temperature, porous sol–gel ceramics represent a relatively new class of materials for the immobilization of biomolecules. The rational design of sol–gel sensing materials, based on the judicious choice of the starting alkoxide, encapsulated reagents, and preparation conditions, allows tailoring of material properties in a wide range,

Joseph Wang

1999-01-01

64

Photoluminescence of sol-gel-prepared hafnia  

NASA Astrophysics Data System (ADS)

We employed a sol-gel route followed by a thermal treatment (up to 1000 °C) to prepare crystalline (monoclinic) hafnium dioxide. Thorough steady-state and time-resolved photoluminescence characterization of the material within the temperature range of 10-300 K was conducted by using various excitation sources. The most prominent spectroscopic feature of the material was an intense broad emission band centered at 2.3-2.5 eV with an associated excitation band centered at 4.2-4.4 eV (well below the bandgap of monoclinic hafnia). The emission was characterized by an essentially non-exponential, thermally stimulated decay and exposed a marked blue shift with the increase of temperature from 10 to 300 K. Relation of the emission to the intrinsic defects of hafnia is discussed.

Kiisk, Valter; Lange, Sven; Utt, Kathriin; Tätte, Tanel; Mändar, Hugo; Sildos, Ilmo

2010-01-01

65

Absence of free carrier and paramagnetism in cobalt-doped ZnO nanoparticles synthesized at low temperature using citrate sol-gel route  

NASA Astrophysics Data System (ADS)

Cobalt-doped ZnO nanoparticles have been synthesized using a simple citrate sol-gel auto-combustion method. The XRD confirms nano-single phase and Wurtzite structure. Increased cobalt solubility from 15 to 20 % was observed in ZnO matrix due to low temperature synthesis. Room temperature paramagnetic contribution is observed for all the samples, since cobalt is a neutral dopant and no free carriers are produced. Normally, ferromagnetism is observed in ZnO due to carrier mediated interaction between transition metal ions and free carriers. Hence no ferromagnetism was observed and only paramagnetism was observed due to non-availability of free carriers for long range ferromagnetic interaction in our system. At higher doping, peak broadening of the highly intense XRD peak (101) was observed indicating formation of cobalt cluster (metal-metal) which reduces paramagnetism due to antiferromagnetic interaction and the magnetization value decreases to 0.00456 from 0.0076 emu/g. Absence of photoluminescence peak at 520 nm due to oxygen related defects also supports, the presence of paramagnetism in our samples, since oxygen defects are the another source of ferromagnetism in ZnO. Indirect evidence for the presence of cobalt clustering is also obtained from the photoluminescence studies which lead to concentration quenching of peaks. Photoluminescence studies exhibit NBE peak at 412 nm and defect peaks at 471 and 672 nm. The intensity of red emission peak at 672 nm remains constant whereas the intensity of the peaks at 412 and 471 nm increases and then decreases due to doping induced disorder leading to concentration quenching.

Sivagamasundari, A.; Pugaze, R.; Chandrasekar, S.; Rajagopan, S.; Kannan, R.

2013-10-01

66

Sol-gel chemistry by ring-opening polymerization  

SciTech Connect

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.

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.

2000-02-07

67

Nanostructured energetic materials using sol-gel methodologies  

SciTech Connect

The fundamental differences between energetic composites and energetic materials made from a monomolecular approach are the energy density attainable and the energy release rates. For the past 4 years, we have been exploiting sol-gel chemistry as a route to process energetic materials on a microstructural scale. At the last ISA conference, we described four specific sol-gel approaches to fabricating energetic materials and presented our early work and results on two methods - solution crystallization and powder addition. Here, we detail our work on a third approach, energetic nanocomposites. Synthesis of thermitic types of energetic nanocomposites are presented using transition and main group metal-oxide skeletons. Results on characterization of structure and performance will also be given.

Tillotson, T M; Simpson, R L; Hrubesh, L W; Gash, A E; Thomas, I M; Poco, J F

2000-09-27

68

Composite sol-gel ceramics  

NASA Astrophysics Data System (ADS)

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.

Yang, Quanzu

1999-11-01

69

Textural properties of sol-gel silicoaluminates  

Microsoft Academic Search

Silicoaluminates were synthesized from Al and Si alkoxides by the sol-gel method and characterized by FTIR spectroscopy and specific BET areas. The water and aluminate ion concnetration effects were studied.

Tessy Lopez; Metropolitana Iztapalapa

1992-01-01

70

Sol-gel antireflective coating on plastics  

DOEpatents

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.

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

1990-01-01

71

Dip coating of sol-gels.  

National Technical Information Service (NTIS)

Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface...

A. J. Hurd C. J. Brinker P. R. Schunk

1991-01-01

72

Sol-gel deposited electrochromic coatings  

SciTech Connect

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].

Ozer, N.; Lampert, C.M.

1995-06-01

73

Sol-gel deposited electrochromic coatings.  

National Technical Information Service (NTIS)

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 ...

N. Ozer C. M. Lampert

1995-01-01

74

Sol-gel technology for biomedical engineering  

Microsoft Academic Search

Sol-gel derived silica possess many promising features, including low-temperature preparation procedure, porosity, chemical and physical stability. Applications exploiting porous materials to encapsulate sensor molecules, enzymes and many other compounds, are devel- oping rapidly. In this paper some potential applications, with emphasis on biomedical and environmental ones, are reviewed. The material preparation procedure is described and practical remarks on silica-based sol-gels

H. PODBIELSKA; A. ULATOWSKA-JAR

75

Germania sol-gel waveguides for optical amplifiers  

NASA Astrophysics Data System (ADS)

Sol-gel is one of the possible production techniques of silica-on-silicon integrated optical devices, combining low cost with a great flexibility. In the frame of a European project, we have investigated the application of the sol-gel technique for the realization of an erbium-doped optical amplifier. In particular we developed GeO2-SiO2-Al2O3 sol-gel waveguides doped with Er. The material was optimized in terms of heat treatments, Al2O3 co- doping content and Er doping level. RBS measurements showed that well densified films could be obtained heating the coatings at 700 degrees C in O2 flux. Waveguide properties were tested measuring the propagation losses at 840 nm. In the planar waveguide pumped at 980 nm, erbium showed fluorescence around 1530 nm with up to 6.5 ms. In order to achieve lateral confinement, the planar waveguides were co-doped with Na2O and channel waveguides were fabricated by ion exchange. The feasibility of sodium-silver and sodium-potassium ion exchange was demonstrated. The influence of the process parameters on passive and active optical properties of the films was studied and straight channel waveguides with Gaussian mode profiles were obtained by the sodium-silver route.

Martucci, Alessandro; Guglielmi, Massimo; Fick, Jochen; Pelli, Stefano; Forastiere, Michele A.; Righini, Giancarlo C.; Battaglin, C.

2000-05-01

76

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

Microsoft Academic Search

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

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

1999-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

78

Hybrid sol-gel optical materials  

DOEpatents

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.

Zeigler, J.M.

1993-04-20

79

Neutron detector using sol-gel absorber  

DOEpatents

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.

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

1999-01-01

80

Optical bonding with fast sol-gel  

NASA Astrophysics Data System (ADS)

We investigate here the properties of fast sol-gel for optical bonding. The precursors of the fast sol-gel material are organically modified alkoxides generating a transparent hybrid (organic-inorganic) substance with silica glass-like properties whose index of refraction can be modified by the addition of various metal-oxides. The fast sol-gel method consists of rapid fabrication of a viscous resin and its subsequent dilution for long shelf life use. This material, when used as an adhesive offers the option of either a thermal or UV curing procedure. We demonstrate a bonding strength of ~ 10 MPa when a 15 ?m layer is applied between two glass elements. The bonding remained stable after an extensive -40°C - 120°C temperature cycling with minimal residual solvent evaporation at 150°C. The fast sol-gel material was tested for optical bonding between silica bulks, between silica bulk and silicon wafers and as an adhesive in silica fibre couplers.

Gvishi, R.; Pokrass, M.; Strum, G.

2009-06-01

81

Sol-Gel Based Electrochemical Biosensors.  

National Technical Information Service (NTIS)

This work is based on the use of the sol-gel process to encapsulate biomolecules in a porous silicate matrix. The porosity of the matrix is such that small molecules and ions can readily diffuse into the materials while the much larger proteins remain tra...

B. C. Dave B. Dunn J. S. Valentine J. I. Zink

1996-01-01

82

DTA and TGA characterization of sol-gel hydrotalcites  

Microsoft Academic Search

Double layered hydroxides with hydrotalcite structure were synthesized by the sol-gel precess using aluminum and magnesium alkoxides as precursors. The thermal decomposition of sol-gel hydrotalcites was studied by TGA and DTA methods. The sol-gel hydrotalcites show thermal stability up to 550 °C.

T. Lopez; E. Ramos; P. Bosch; M. Asomoza; R. Gomez

1997-01-01

83

The Sol-Gel Process for Nano-Technologies: New Nanocomposites with Interesting Optical and Mechanical Properties  

Microsoft Academic Search

Various nanocomposite systems have been synthesized by sol-gel routes. For this reason, prefabricated nanoparticles (SiO2 sols or boehmite powder) have been dispersed after surface modification in sol-gel-derived organically modified or polymeric ligand matrices. In all cases, a significant effect on dispersibility by surface modification could be observed. After curing, the mechanical or optical properties depend strongly on the dispersion and

H. K. Schmidt; E. Geiter; M. Mennig; H. Krug; C. Becker; R.-P. Winkler

1998-01-01

84

Sol-gel PZT and Mn-doped PZT thin films for pyroelectric applications  

Microsoft Academic Search

Thin films of ferroelectric lead zirconate titanate (PbZr0.3Ti0.7O3 PZT30\\/70) and manganese-doped lead zirconate titanate ((Pb(Zr0.3Ti0.7)1- xMnx)O3, where x = 0.01, PM01ZT30\\/70; and x = 0.03, PM03ZT30\\/70) have been prepared using sol-gel processing techniques. These materials can be used as the pyroelectric thin films in uncooled infrared detectors. The thin films were prepared via a sol-gel route based on a hybrid

Q. Zhang; R. W. Whatmore

2001-01-01

85

Temperature dependent EXAFS measurements on YGG during a sol-gel process  

Microsoft Academic Search

Temperature dependent X-ray absorption spectroscopy has been used as a local probe to elucidate the structure of yttrium gallium garnet produced by a sol-gel route. The treatment of our experimental data includes a cumulant expansion analysis taking into account the asymmetry of the pair distribution function resulting from disorder at high temperature.

C. Landron; N. Gautier; A. Douy; J. P. Coutures; D. Bazin

1995-01-01

86

Water-based sol–gel synthesis of hydroxyapatite: process development  

Microsoft Academic Search

Hydroxyapatite (HA) ceramics were synthesized using a sol–gel route with triethyl phosphite and calcium nitrate as phosphorus and calcium precursors, respectively. Two solvents, water and anhydrous ethanol, were used as diluting media for HA sol preparation. The sols were stable and no gelling occurred in ambient environment for over 5 days. The sols became a white gel only after removal

Dean-Mo Liu; T Troczynski; Wenjea J Tseng

2001-01-01

87

Sol-gel coating on acoustic wave devices: Thin film characterization and chemical sensor development  

Microsoft Academic Search

We have investigated the use of porous oxide coatings, formed using sol-gel chemistry routes, as the discriminating elements of acoustic wave (AW) chemical sensors. These coatings provide several unique advantages: durability, high adsorption capacity based on large surface areas, and chemical selectivity based on both molecular size and chemical interactions. The porosity of these coatings is determined by performing nitrogen

G. G. Frye; C. J. Brinker; A. J. Ricco; S. J. martin; J. Hilliard; D. H. Doughty

1990-01-01

88

Preparation and electrical properties of Pb(Zr 0.52Ti 0.48)O 3 thick films embedded with ZnO nanowhiskers by a hybrid sol–gel route  

Microsoft Academic Search

Pb(Zr0.52Ti0.48)O3 thick films embedded with ZnO nanowhiskers (ZnOw–PZT) were successfully prepared on Pt\\/Cr\\/SiO2\\/Si substrates by a hybrid sol–gel method via spin-coating ZnOw suspension and PZT sol. Effects of annealing time and thickness on the corresponding orientation and crystallization of ZnOw–PZT films are investigated. XRD and SEM results show that ZnOw–PZT composite thick films have perovskite structure and high-quality film surface.

Q. L. Zhao; M. S. Cao; J. Yuan; W. L. Song; R. Lu; D. W. Wang; D. Q. Zhang

2010-01-01

89

Sol-gels and chemical sensors  

Microsoft Academic Search

We review the principles of optical and electrochemical sensors based on the use of the sol-gel technique, in particular their\\u000a fabrication, working principles, and various configurations. We also report on potential applications, e.g. to environmental\\u000a and clinical analysis, to gas sensing, and to bioprocess monitoring. Methods are critically reviewed for making such sensors,\\u000a how to encapsulate organic, inorganic and biological

Otto S. Wolfbeis; Renata Reisfeld; Ines Oehme

90

Catalyst Doped Sol-Gel Materials  

Microsoft Academic Search

\\u000a An important subject in catalysis is the synthesis of metallic supported catalysts. The structural and textural modification\\u000a of this materials can improve the activity, selectivity or catalyst lifetime. Research groups have recently shown a great\\u000a interest in the preparation of metal doped catalysts by the well known sol-gel method. This process consists in the hydrolysis\\u000a and condensation of an alkoxide

Tessy López; Ricardo Gómez

91

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

NASA Astrophysics Data System (ADS)

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.

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

92

Sol-gel silica-on-silicon buried-channel EDWAs  

Microsoft Academic Search

Silica-on-silicon erbium-doped waveguide amplifiers (EDWAs) fabricated by the sol-gel route are demonstrated. The preparation of stable sols is first described, with emphasis on identifying chemical routes that allow the incorporation of sufficient concentration of erbium without precipitation or gelation. Erbium-doped glasses containing various codopants, such as phosphorus, aluminum, germanium and ytterbium are formed and used in the construction of buried

W. Huang; R. R. A. Syms

2003-01-01

93

Substituent effects on the sol-gel chemistry of organotrialkoxysilanes  

SciTech Connect

Silsesquioxanes have been the subject of intensive study in the past and are becoming important again as a vehicle for introducing organic functionalities into hybrid organic-inorganic materials through sol-gel processing. Depending on the application, the target hybrid material may be required to be a highly cross-linked, insoluble gel or a soluble polymer that can be cast as a thin film or coating. The former has applications such as catalyst supports and separations media; the latter is an economically important method for surface modification or compatiblization for applying adhesives or introducing fillers. Polysilsesquioxanes are readily prepared through the hydrolysis and condensation of organotrialkoxysilanes, though organotriaminosilane and organotrihalosilane monomers can also be used. This paper explores the kinetics of the preparation route.

LOY, DOUGLAS A.; BAUGHER, BRIGITTA M.; BAUGHER, COLLEEN R.; SCHNEIDER, DUANE A.; RAHIMIAN, KAMYAR

2000-05-09

94

Examination of the haemolytic activity of sol-gel materials  

NASA Astrophysics Data System (ADS)

Recently, the sol-gel based biomaterials are extendedly investigated with emphasis on theirs various applications, including medical ones. In this respect it is important to investigate the influence of sol-gel matrices on biological systems. The results of laboratory and biological testing of aqueous extracts of sol-gels are presented in this work. It was proved that it is possible to produce the sol-gel derived materials that will be non-haemolytic. This can be achieved by heating the materials in elevated temperatures. This effect can also be reached by suitably long aging (minimum 6 months).

Ulatowska-Jarza, Agnieszka; Podbielska, Halina; Holowacz, Iwona; Lechna-Marczynska, Monika I.; Szymonowicz, Maria; Staniszewska-Kus, Jolanta; Paluch, Danuta

2001-10-01

95

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

PubMed

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

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

2010-12-08

96

UV-cured sol-gel broadband antireflective and scratch-resistant coating for CRT  

NASA Astrophysics Data System (ADS)

A novel optical coating devoted to reduction of CRT panel specular reflection has been developed using the sol-gel route. The sol-gel antireflective (AR) coating is made from tantalum and silicon oxide-based solutions. First layer is an hybrid material based on polymeric mixture of tantalum with silicon oxide. Second and third layers are respective containing tantalum oxide and silica polymeric matrix, since they correspond to the high and low index thin film in the optical stack. Sol-gel synthesis has been carried out starting from cheap precursors in order to produce metallic alkoxide-based solution, each one suitable for liquid- deposition technique use such as dip or spin-coating. After layer deposition, a curing step is required. Both thermal and UV-curing could include layer densification and generate final coating properties. UV-curing is performed using short wavelength irradiation and thermal baking step does not exceed 150 degrees C temperature. CRT front panel prototypes have been produced with sol-gel AR-coat for test measurements. The process time including deposition by dip- coating and curing, is about one hour. This three-layer antireflective coating has been optimized to offer scratch- resistance, easy-clean and broadband antireflection properties on CRT panels.

Belleville, Philippe F.; Prene, Philippe; Lambert, Benoit

2000-05-01

97

Sol–gel based sensor for selective formaldehyde determination  

Microsoft Academic Search

We report the development of transparent sol–gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with ?-diketones (for example acetylacetone) in a sol–gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of

Opas Bunkoed; Frank Davis; Proespichaya Kanatharana; Panote Thavarungkul; Séamus P. J. Higson

2010-01-01

98

Synthesis of Phthalocyanine Doped Sol-Gel Materials.  

National Technical Information Service (NTIS)

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 ca...

B. Dunn

1993-01-01

99

Sol-Gel Fluxes for Flux Cored Welding Consumables.  

National Technical Information Service (NTIS)

The feasibility of producing high purity homogeneous welding fluxes by the sol-gel process and the effects that these fluxes have on the welding process were determined. Reagent grade sol-gel welding fluxes were produced by making systematic variations of...

P. S. Dunn C. A. Natalie D. L. Olson

1986-01-01

100

Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase  

ERIC Educational Resources Information Center

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…

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

2010-01-01

101

Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase  

ERIC Educational Resources Information Center

|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…

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

2010-01-01

102

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

SciTech Connect

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. -- Graphical abstract: Geopolymer prepared by the sol-gel route has the same spectroscopic properties as the sample prepared from the natural kaolinite. Display Omitted

Tsai, Yi-Ling [Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan ROC (China); Hanna, John V. [Department of Physics, The University of Warwick, Coventry CV4 7AL (United Kingdom); Lee, Yuan-Ling, E-mail: yuanlinglee@ntu.edu.t [Graduate Institute of Clinical Dentistry, National Taiwan University and Hospital, No. 1, Changde Street, Taipei 10048, Taiwan ROC (China); Smith, Mark E., E-mail: M.E.Smith.1@warwick.ac.u [Department of Physics, The University of Warwick, Coventry CV4 7AL (United Kingdom); Chan, Jerry C.C., E-mail: chanjcc@ntu.edu.t [Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan ROC (China)

2010-12-15

103

Synthesis and characterization of hydroxyapatite obtained from different organic precursors by sol–gel method  

Microsoft Academic Search

The synthesis of four types of hydroxyapatite synthesized from calcium chloride and four different organic phosphites is presented.\\u000a The method of synthesis chosen is the sol–gel route, which has a number of advantages compared to other methods, like the\\u000a intimate contact between reactants and the milder synthesis conditions. The samples were thermally treated, the TG\\/DTG\\/DTA\\u000a curves being obtained at four

Alexandra Ioi?escu; Gabriela Vlase; T. Vlase; G. Ilia; N. Doca

2009-01-01

104

Sol-gel processing of energetic materials  

SciTech Connect

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.

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

1997-08-18

105

Cr-free Fe-based water-gas shift catalysts prepared through propylene oxide-assisted sol–gel technique  

Microsoft Academic Search

Chromium-free Fe-based water-gas shift catalysts were prepared through a gelation agent-assisted sol–gel route utilizing propylene oxide and citric acid as the gelation agents. Catalyst preparation using propylene oxide is a “one-pot” method that is cleaner, more eco-friendly and less time consuming over our previously developed sol–gel method for preparing Fe–Al–Cu and leads to comparable activities. The effect of Cu loading

Preshit Gawade; Burcu Mirkelamoglu; Bing Tan; Umit S. Ozkan

2010-01-01

106

Current issues in sol-gel reaction kinetics  

SciTech Connect

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.

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

1990-01-01

107

Wet powder processing of sol-gel derived mesoporous silica-hydroxyapatite hybrid powders.  

PubMed

This paper describes a method by which a porous silica coating layer can be obtained on different apatite particles through a simple sol-gel synthesis route. Sol-gel derived powders of hydroxyapatite (HAP) and beta tricalciumphosphate (beta-TCP) were coated with a mesoporous silica using C16TAB (hexadecyltrimethylammonium bromide) as a template in order to induce mesophase formation. Further calcination of the material removes the template from the mesophase and leaves a highly ordered hexagonal arranged mesoporous silica structure with a core of HAP/beta-TCP. The phase purity of the SiO2/apatite composites has been thoroughly investigated by the means of FT-IR, XRD, and solid state 31P MAS NMR. The phase purity of these materials is shown to be dependent on the solubility properties of the used apatites. The hybrid materials are suitable as a multifunctional biomaterial where osteoconductive properties can be combined with drug delivery. PMID:17037853

Andersson, Jenny; Johannessen, Espen; Areva, Sami; Järn, Mikael; Lindén, Mika

2006-08-01

108

Structural and Dynamical Properties of the Sol-Gel Transition.  

National Technical Information Service (NTIS)

A variety of experimental techniques (multinuclear NMR, Raman, fluorescence polarization, small-angle neutron scattering, viscosity, turbidity, static and dynamic light scattering experiments) have been employed to investigate the nature of the sol-gel tr...

R. Winter D. W. Hua X. Song W. Mantulin J. Jonas

1990-01-01

109

Sol-gel film formation by dip coating.  

National Technical Information Service (NTIS)

In this paper, the physical aspects of sol-gel film formation are discussed. The equations governing the steady state film profile, controlled by hydrodynamic flow, capillary pressure and evaporation, are presented along with representative data obtained ...

A. J. Hurd C. J. Brinker

1990-01-01

110

Structural and Dynamical Properties of the Sol-Gel Transition.  

National Technical Information Service (NTIS)

Different experimental techniques have been employed to investigate the macroscopic and microscopic structural and dynamical properties of the sol-gel transition of tetramethoxysilicate. In conclusion, we note that no drastic changes in structure occur at...

R. Winter D. W. Hua X. Song J. Jonas

1988-01-01

111

Dip coating of sol-gels  

SciTech Connect

Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (<1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. We set out to understand these phenomena with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape. 2 refs., 2 figs.

Schunk, P.R.; Hurd, A.J.; Brinker, C.J.

1991-01-01

112

Opportunities for sol-gel materials in fuel cells  

Microsoft Academic Search

Fuel cells are electrochemical devices that convert the chemical energy of a fuel and oxidant directly to electrical energy. Three types of fuel cells are (a) proton-exchange membrane fuel cells (PEMFC), (b) molten carbonate fuel cells (MCFC) and (c) solid oxide fuel cells (SOFC). In each case, there is a role for sol-gel processing. In the case of PEMFC, sol-gel

LISA C. KLEIN

113

New nonlinear Sol-Gel films exhibiting photorefractivity  

SciTech Connect

The first photorefractive sol-gel film has been prepared by copolymerization of tetraethoxysilane and modified silane monomers having push-pull azobenzene and carbazole moieties. Thin films poled by corona discharge exhibited large quadratic nonlinearities (electrooptic coefficient r{sub 33}{approx} 17 pm/V, at 633 nm). Preliminary two-beam coupling measurements, without applying external electric field, showed photorefractivity of this new sol-gel material. 21 refs., 3 figs.

Chaput, F.; Boilot, J.P.; Cargnelli, K. [Ecole Polytechnique, Palaiseau (France)] [and others

1996-02-01

114

Sol-gel synthesis and characterization of yttrium gallium garnets  

Microsoft Academic Search

Precursor powders for yttrium gallium garnet (Y3Ga5O12, YGG) were prepared by a simple sol-gel method based on the formation of metal chelates in aqueous solvents. A systematic study of sol-gel technique synthesized YGG samples is presented using different complexing agents. Six high-purity organic substances were used as complexing agents, namely, tartaric acid, 1,2-ethanediol, citric acid, ethylene diamine tetra-acetic acid (EDTA),

Asta Leleckaite; Sigita Urbonaite; Kaia Tõnsuaadu; Aivaras Kareiva

2005-01-01

115

Silica Sol–Gel Biocomposite Materials for Sensor Development  

Microsoft Academic Search

The performance of a silica sol–gel biosensor is intimately related to the characteristics of an encapsulated guest molecule.\\u000a The effect of charge, size, and polarity on the behavior of the encapsulate was investigated using both ensemble measurements\\u000a and single-molecule spectroscopy. Simply by monitoring the mobility of individual encapsulates, the heterogeneous microscopic\\u000a environment within a silica sol–gel was directly revealed. Regardless

Yongyao Zhou; Tami A. Martyn; James W. Gilliland

116

Interstitial laser coagulation in vitro with sol–gel applicators  

Microsoft Academic Search

In the past years new materials have been developed for innovative applications in the field of medical technology. The sol–gel-coated applicators were prepared from the silicate precursor tetraethylorthosilicate (TEOS) mixed with the solvent ethanol in acid to catalyze hydrolysis. The sol–gel layers were deposited on the fiber optic core, substituting the original fiber coating which had been removed. In these

Halina Podbielska; Iwona Ho?owacz; Uwe Bindig; Agnieszka Ulatowska-Jar?a; Ewa Rohde; Eicke-Eric Scheller

2006-01-01

117

Characterization of sol-gel surfaces for biomedical applications  

Microsoft Academic Search

The aim of the present study was to characterize sol-gel derived titania coatings prepared by dipping. The surface characterization was carried out using X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF SIMS), combined with X-ray diffraction (XRD) and thermal analysis. Sol-gel derived titania surfaces mimicked the surface chemistry of the natural oxide layer found on

D. B. Haddow; P. F. James; R. VAN NOORT

1996-01-01

118

Sol-gel processing for fiber optic applications  

NASA Astrophysics Data System (ADS)

The sol-gel process is a versatile process for the preparation of many types of glass and ceramics. This includes optical fibers. The general principles of sol-gel processing are described first. This is followed by details of the specific methods that can be used for the fabrication of optical fibers. Finally, some conclusions are drawn as to the commercial potential of the various methods.

Thomas, Ian M.

1989-11-01

119

Dimer formation in phthalocyanine-doped sol-gel materials  

NASA Astrophysics Data System (ADS)

A number of different organic molecules have been used as optical probes of the sol-gel process. There is relatively little information, however, as to whether these molecules remain well isolated within the sol-gel structure or if they tend to form dimers or higher aggregates within the network. This issue is particularly important for doped sol-gel optical materials as dimer formation can exert a significant influence on the optical properties of dyes. The present paper uses the optical absorption characteristics of copper phthalocyanine tetrasulfonate (CuPcts) to determine how the state of the dye is affected by the chemical changes during the sol-gel process. The absorption spectra of CuPcts indicate that the dye molecules are dimerized in acid-catalyzed silica xerogels prepared from TMOS. The dimerization is largely controlled by the chemical environment inside the pores. By using appropriate reference solutions, we are able to identify the factors which cause dimerization and the stages of the sol-gel-xerogel transformation when the dimers form. These factors include the quantity of solvent remaining in the pores, the alcohol/water content of the solvent and its acidity. It is shown that by modifying the sol-gel processing conditions and the solvent chemistry within the pores, it is possible to reduce significantly dimer formation in silica xerogels.

Fuqua, Peter D.; Dunn, Bruce S.; Zink, Jeffrey I.

1994-10-01

120

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

NASA Astrophysics Data System (ADS)

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 starting from sol-gel precursors can offer a cost-effective and more flexible large-scale alternative synthesis route in comparison to the common used vacuum techniques. This work describes the deposition of thin NdBa2Cu3O7-y layers on SrTiO3 single crystals based on a new sol-gel dip coating process using aqueous precursor solutions. Two inorganic aqueous sol-gel routes were investigated, a metal nitrate - citric acid based and a metal acetate - triethanol amine based solution.

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

2006-06-01

121

Sol-gel encapsulation for controlled drug release and biosensing  

NASA Astrophysics Data System (ADS)

The main focus of this dissertation is to investigate the use of sol-gel encapsulation of biomolecules for controlled drug release and biosensing. Controlled drug release has advantages over conventional therapies in that it maintains a constant, therapeutic drug level in the body for prolonged periods of time. The anti-hypertensive drug Captopril was encapsulated in sol-gel materials of various forms, such as silica xerogels and nanoparticles. The primary objective was to show that sol-gel silica materials are promising drug carriers for controlled release by releasing Captopril at a release rate that is within a therapeutic range. We were able to demonstrate desired release for over a week from Captopril-doped silica xerogels and overall release from Captopril-doped silica nanoparticles. As an aside, the antibiotic Vancomycin was also encapsulated in these porous silica nanoparticles and desired release was obtained for several days in-vitro. The second part of the dissertation focuses on immobilizing antibodies and proteins in sol-gel to detect various analytes, such as hormones and amino acids. Sol-gel competitive immunoassays on antibody-doped silica xerogels were used for hormone detection. Calibration for insulin and C-peptide in standard solutions was obtained in the nM range. In addition, NASA-Ames is also interested in developing a reagentless biosensor using bacterial periplasmic binding proteins (bPBPs) to detect specific biomarkers, such as amino acids and phosphate. These bPBPs were doubly labeled with two different fluorophores and encapsulated in silica xerogels. Ligand-binding experiments were performed on the bPBPs in solution and in sol-gel. Ligand-binding was monitored by fluorescence resonance energy transfer (FRET) between the two fluorophores on the bPBP. Titration data show that one bPBP has retained its ligand-binding properties in sol-gel.

Fang, Jonathan

122

Sol-Gel Production; Proceedings of the First International Conference on Application and Commercialization of Sol-Gel Processing Held in Saarbruecken, Germany on 24-25 May 1993.  

National Technical Information Service (NTIS)

Partial contents: Sol-Gel Production of Silica Microparticles; Synthesis of Zircon-Based Ceramic Pigments via Sol-Gel Methods; Sol-Gel Ceramic Pigments; Characterization of Oxide Layers Deposited by Sol-Gel; Mechanical Precision in Sol-Gel Manufacturing o...

H. Schmidt

1998-01-01

123

Structural evolution and stability of sol gel biocatalysts  

NASA Astrophysics Data System (ADS)

Immobilisation strategies for catalytic enzymes are important as they allow recovery and reuse of the biocatalysts. In this work, sol gel matrices have been used to immobilise Candida antarctica lipase B (CALB), a commonly used industrial enzyme. The sol gel bioencapsulate is produced through fluoride-catalysed hydrolysis of mixtures of tetramethylorthosilicate (TMOS) and methyltrimethoxysilane (MTMS) in the presence of CALB, yielding materials with controlled pore sizes and surface chemistries. Sol gel matrices prolong the catalytic life and enhance the activity of CALB, although the molecular basis for this effect has yet to be elucidated due to the limitations of analytical techniques applied to date. Small angle neutron scattering (SANS) allows such multi-component systems to be characterised through contrast matching. In the sol gel bioencapsulate system at the contrast match point for silica, residual scattering intensity is due to the CALB and density fluctuations in the matrix. A SANS contrast variation series found the match point for the silica matrix, both with and without enzyme present, to be around 35%. The model presented here proposes a mechanism for the interaction between CALB and the surrounding sol gel matrix, and the observed improvement in enzyme activity and matrix strength. Essentially, the inclusion of CALB modulates silicate speciation during evolution of the inorganic network, leading to associated variations in SANS contrast. The SANS protocol developed here may be applied more generally to other encapsulated enzyme systems.

Rodgers, L. E.; Knott, R. B.; Holden, P. J.; Pike, K. J.; Hanna, J. V.; Foster, L. J. R.; Bartlett, J. R.

2006-11-01

124

Optical spectroscopy of trivalent chromium in sol-gel lithium niobate  

SciTech Connect

We report on the characterization of sol-gel derived lithium niobate via trivalent chromium probe ions, a study that is motivated by recent reports on the synthesis of high quality sol-gel lithium niobate (LiNbO{sub 3}). In order to assess the quality of sol-gel derived LiNbO{sub 3}, we incorporate Cr{sup 3+} during the hydrolysis stage of the sol-gel process. A comparison of the Cr{sup 3+} emission and photoexcitation data on both sol-gel and melt-grown LiNbO{sub 3} shows that the sol-gel derived material is highly stoichiometric.

Krebs, J.K.; Happek, U. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, Pennsylvania 17604 (United States); Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602-2451 (United States)

2005-12-19

125

A modified sol-gel process for multiferroic nanocomposite films  

NASA Astrophysics Data System (ADS)

Multiferroic CoFe2O4-Pb(Zr,Ti)O3 (CFO-PZT) composite films with nanoscale mixture of the two phases were prepared by a modified sol-gel process, in which a mixed precursor solution of both CFO and PZT was used. X-ray diffraction and transmission electron microscopy examinations revealed the coexistence of perovskite PZT and spinel CFO that were mixed in nanoscale with mean grain sizes of 5-10 nm. Magnetic properties of the CFO-PZT nanocomposite were examined, which were consistent with their microstructures. The magnetoelectric coupling between CFO and PZT was demonstrated by an external magnetic field induced electric polarization change. This modified sol-gel processing provides an alternative for multiferroic composite films, which is simpler and easier to control compared to the conventional layer-layer sol-gel process for multiferroic composite films.

Liu, Ming; Li, Xin; Lou, Jing; Zheng, Shijian; Du, Kui; Sun, Nian X.

2007-10-01

126

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

127

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

Microsoft Academic Search

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

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

128

Sol-gel laser coatings at CEA Limeil-Valenton  

NASA Astrophysics Data System (ADS)

CEA Limeil-Valenton has embarked in a project called 'laser megajoule' (LMJ) consisting of the construction of a 2-MJ/500- TW (351-nm) pulsed Nd:glass laser and devoted to inertial confinement fusion research in France. Room temperature and atmospheric pressure deposited sol-gel coatings for antireflective (AR), highly reflective (HR) and polarizer uses, and silicone films for environmental protection have displayed remarkable optical and laser strength performance. Such coatings can be applied onto large area and at a low cost compared to conventional vacuum deposition techniques. CEA Limeil-Valenton is also maintaining sustained efforts to promote the sol-gel technology in other areas.

Floch, Herve G.; Belleville, Philippe F.

1997-10-01

129

Sol-gel synthesis of phosphate ceramic composites II  

SciTech Connect

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.}

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

130

Energy Transfer Studies of Tb Doped Sol-gel glasses  

NASA Astrophysics Data System (ADS)

We present recent studies of the effects of energy transfer on the time evolution of Tb^3+ emission lines in sol-gel glasses. Utilizing a multichannel analyzer we are now able to measure the lifetimes of weak emission lines from the sol-gel glasses. The measured decay signals have been analyzed using theoretical models to gain insight into the distribution of the rare earth ions in doped glasses. We will discuss the observed energy dynamics as the result of chemical treatments of the glass and fabrication variables.

Sanchez, Freddy; Montejo, Genderzon; Wenzlau, Dylan; Hoffman, Kurt

2010-10-01

131

Characterization of Hafnia Powder Prepared from an Oxychloride Sol Gel  

SciTech Connect

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.

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

132

Fabrication of sol-gel optical element with dichromated gelatin as photoresist  

NASA Astrophysics Data System (ADS)

Based on the cleaving-etch method and hardening of dichromated gelatin (DCG), DCG was used as a photoresist for fabricating sol-gel optical elements. Anti-etch characteristic of hardened gelatin was investigated. Compared with etching of sol-gel, hardened gelatin could be used as photoresist to fabricate sol-gel optical elements. Coating condition of sol-gel was investigated. The results showed that thickness of coatings was independent of aging time of the sol-gel solution during a month. Thick multilayer sol-gel coatings were etched with HF solution after ammonia treatment. Good linearity was obtained, which showed adaptation of sol-gel coatings to fabricate optical elements. Using DCG resist the cleaving etch with method, the image of mask was transferred into sol-gel coatings. It was tested imitatively to smooth laser beams and the result was satisfactory.

Pang, Lin; Wei, Hui; Zeng, Yongqun; Chen, Bo; Guo, Lurong

1998-08-01

133

Flow injection fluorescence immunoassay for gentamicin using sol-gel-derived mesoporous biomaterial  

Microsoft Academic Search

Sol-gel-derived mesoporous biomaterials were used for the first time in the flow-injection fluorescence immunoassay system. Anti-gentamicin antibody was immobilized in a mesoporous sol-gel material using tetramethoxysilane as a precursor and poly(ethylene glycol) as a template. The sol-gel glass was used to develop an immunoaffinity column for the flow-injection immunoassay of gentamicin. Little unspecific adsorption of gentamicin on the sol-gel and

Huang-Hao Yang; Qing-Zhi Zhu; Hui-Ying Qu; Xiao-Lan Chen; Ma-Tai Ding; Jin-Gou Xu

2002-01-01

134

Sol-Gel Synthesis and Sensing Study of Perovskite CaCu3Ti4O12 Nanopowders  

Microsoft Academic Search

CaCu3Ti4O12 nanopowders were fabricated by a facile effective sol-gel route using tetrabutyl titanate, calcium acetate and cupric nitrate as precursors. The intermediate xerogel was characterized by thermal analyzer and the products with different calcination temperature were then studied by IR spectrum. Further X-ray diffraction, transmission electronic microscopy, high-resolution transmission electron microscopy and energy dispersive X-ray spectrum were used to characterize

Yang Tian; Xiaojie Zhang; Yiyi Yang; Zhen Liu; Xiaozhu Huang

2011-01-01

135

Thick-film gas sensors based on vanadium–titanium oxide powders prepared by sol-gel synthesis  

Microsoft Academic Search

Two titania powders modified by 10 at.% of vanadium were prepared by two different sol-gel routes. The powders fired at 650 °C had the rutile structure. These powders were used to produce prototype thick-film sensors. Four series of thick-film samples were fabricated by screen-printing, fired for 1 h at 650 and 850 °C. The morphology and gas-sensing properties were examined and compared

Maria Cristina Carotta; Matteo Ferronia; Sandro Gherardi; Vincenzo Guidi; Cesare Malagù; Giuliano Martinelli; Michele Sacerdoti; Maria Luisa Di Vona; Silvia Licoccia; Enrico Traversa

2004-01-01

136

Safe and Environmentally Acceptable Sol-Gel-Derived Pyrophoric Pyrotechnics.  

National Technical Information Service (NTIS)

It was demonstrated that highly porous sol-gel derived iron (III) oxide materials could be reduced to sub-micron-sized metallic iron by heating the materials to intermediate temperatures in a hydrogen atmosphere. Through a large number of experiments comp...

R. L. Simpson W. Hubble B. Stevenson A. Gash J. Satcher

2004-01-01

137

Sol-gel matrices for direct colorimetric detection of analytes  

DOEpatents

The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

Charych, Deborah H. (Albany, CA); Sasaki, Darryl (Albuquerque, NM); Yamanaka, Stacey (Dallas, TX)

2000-01-01

138

Current issues in sol-gel reaction kinetics.  

National Technical Information Service (NTIS)

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 f...

R. A. Assink B. D. Kay

1990-01-01

139

Sol-Gel Matrices For Direct Colorimetric Detection Of Analytes  

DOEpatents

The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

Charych, Deborah H. (Albany, CA); Sasaki, Darryl (Albuquerque, NM); Yamanaka, Stacey (Dallas, TX)

2002-11-26

140

Sol—Gel preparation of supported metal catalysts  

Microsoft Academic Search

Variables important in the synthesis of supported metal catalysts using the sol-gel method are reviewed. Potential applications of these materials are presented with emphasis on: thermally resistant materials, catalysts with low deactivation rates, high surface area materials, catalytic membrane reactors and high surface area superacid materials. Emphasis is on synthesis conditions including the control of variables which enable the preparation

Richard D. Gonzalez; Tessie Lopez; Ricardo Gomez

1997-01-01

141

Platinum acetylacetonate effect on sol-gel derived titania catalysts  

Microsoft Academic Search

The band gap (Eg) of sol-gel derived titania has been determined using UV-Vis spectroscopy. When platinum acetylacetonate\\u000a was added during titanium tetrabutoxide gelation, a significant diminution of the band gap was observed. Low Eg values were\\u000a stabilized on heat-treated platinum\\/titania samples.

T. Lopez; E. Sanchez; R. Gomez; L. Ioffe; Y. Borodko

1997-01-01

142

Inorganic Sensing Using Organofunctional Sol-Gel Materials  

PubMed Central

This Account describes recent work in the development and applications of sol-gel sensors for concentrated strong acids/bases and metal ions. The use of sol-gel films doped with organic indicators for the optical sensing of concentrated strong acids (HCl 1-10 M) and bases (NaOH 1-10 M) has been explored, and the development of dual optical sensor approaches for ternary systems (HCl-salt-H2O and NaOH-alcohol-H2O) to give acid and salt as well as base and alcohol concentrations is discussed. The preparation of transparent, ligand-grafted sol-gel monoliths is also described, and their use in the analysis of both metal cations (Cu2+) and anions [Cr(VI)] is presented. A new model using both metal ion diffusion and immobilization by the ligands in such monoliths has been developed to give metal concentrations using the optical monolith sensors. In addition to optical sensing, a method utilizing ligand-grafted sol-gel films for analyte preconcentration in the electrochemical determination of Cr(VI) has been explored and is discussed.

Carrington, Nathan A.; Xue, Zi-Ling

2007-01-01

143

Electrospun sol-gel fibers for fluorescence-based sensing  

Microsoft Academic Search

Fluorescence based biosensors have the ability to provide reliable pathogen detection. However, the performance could be improved by enhancing the effective surface area of the biosensor. We report on a new nanofibrous fluorescencebased biosensor, whereas a sol-gel platform mesh was constructed by utilizing electrospinning techniques. Furthermore, incorporating cetyltrimethylammonium bromide (CTAB) and conducting pore-forming techniques resulted in a high surface area

Jasenka Memisevic; Lela Riley; Sheila A. Grant

2009-01-01

144

Protein interactions with nanoporous sol-gel derived bioactive glasses.  

PubMed

Sol-gel derived bioactive glasses are excellent candidates for bone regenerative implant materials as they bond with bone, stimulate bone growth and degrade in the body. Their interactions with proteins are critical to understanding their performance after implantation. This study focuses on the interactions between fibrinogen and sol-gel glass particles of the 70S30C (70 mol.% SiO(2), 30 mol.% CaO composition). Sol-gel silica and melt-derived Bioglass® were also used for comparison. Fibrinogen penetration into the nanoporous glasses was observed by live tracking the fluorescent-labelled fibrinogen with confocal microscopy. The effect of pore size on protein penetration was investigated. Nanoporous networks with modal pore diameters larger than 6 nm were accessible to fibrinogen. When the modal nanopore diameter was decreased to 2 nm or less, the penetration of fibrinogen was inhibited. The surface properties of the glasses, which can be modulated by media pH, glass composition and final stabilisation temperature in the sol-gel process, have effects on fibrinogen adsorption via long-range Coulombic forces before the adsorption and via short-range interactions such as hydrogen bonding after the adsorption. PMID:21757036

Lin, Sen; Van den Bergh, Wouter; Baker, Simon; Jones, Julian R

2011-06-30

145

The controlled release of drugs from emulsified, sol gel processed silica microspheres  

Microsoft Academic Search

Controlled release silica sol gels are room temperature processed, porous, resorbable materials with generally good compatibility. Many molecules including drugs, proteins and growth factors can be released from sol gels and the quantity and duration of the release can vary widely. Processing parameters render these release properties exquisitely versatile. The synthesis of controlled release sol gels typically includes acid catalyzed

Shula Radin; Tiffany Chen; Paul Ducheyne

2009-01-01

146

New insights into uranium (VI) sol-gel processing  

SciTech Connect

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.

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

147

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

SciTech Connect

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.

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

148

Growth of epitaxial LaAlO(sub 3) and CeO(sub 2) films using sol-gel precursors.  

National Technical Information Service (NTIS)

LaAlO(sub 3) and CeO(sub 2) films have been successfully grown using sol-gel precursors. LaAlO(sub 3) precursor solution has been prepared from a metal alkoxide route and spun-cast on a SrTiO(sub 3) (100) single crystal to yield an epitaxial film followin...

S. S. Shoup M. Paranthaman D. B. Beach

1996-01-01

149

Characterization of sol-gel mullite powders  

SciTech Connect

Using tetraethyl orthosilicate and aluminum tri-sec-butoxide as raw materials, two series of mullite gels were prepared, one involving a chemical modification of aluminum alkoxide by ethylacetoacetate, the other one by reacting both alkoxides in a non-homologous alcohol, i.e., isopropyl alcohol or 2-methoxyethanol. For the first route, the excess water or basic conditions promote the formation of nanosized powders that appear X-ray amorphous after the crystallization exotherm on the DTA trace. The same result is obtained for the second route with isopropanol as solvent. The sample preparation strongly influences the ceramic densifications that can vary from 70 to 93 % of the theoretical value after 1,200 C calcination.

Chen, Y.F.; Vilminot, S. [IPCMS, Strasbourg (France). Groupe des Materiaux Inorganiques

1995-03-01

150

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

SciTech Connect

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.

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

151

Sol-gel fabrication of high-quality photomask substrates  

NASA Astrophysics Data System (ADS)

Synthetic silica photomask substrates are currently manufactured by cutting, grinding, and polishing glass boules prepared using a flame hydrolysis process. YTC America is developing an alternative technique, based on sol-gel processing, to fabricate high quality substrates. This new technology allows near net shape fabrication of synthetic silica monoliths, thus eliminating the need for cutting and grinding. The complex relationship between glass properties and process parameters in the formulation, drying, and sintering steps has been determined, and a repeatable process has been established. These substrates meet all SEMI specifications for ULTE hard surface photomask substrates for 248-nm lithography. The technology may also be extended to 193-nm and 157-nm photomask substrates. This sol-gel-based process may represent a unique and cost-effective alternative for manufacturing photomask substrates for deep UV lithography.

Ganguli, Rahul; Meixner, D. L.; Colbern, Steve G.; Gleason, Matt S.; Meyers, Douglas E.; Chaudhuri, Satyabrata R.

2003-06-01

152

Sol-gel synthesis and characterization of yttrium gallium garnets  

NASA Astrophysics Data System (ADS)

Precursor powders for yttrium gallium garnet (Y3Ga5O12, YGG) were prepared by a simple sol-gel method based on the formation of metal chelates in aqueous solvents. A systematic study of sol-gel technique synthesized YGG samples is presented using different complexing agents. Six high-purity organic substances were used as complexing agents, namely, tartaric acid, 1,2-ethanediol, citric acid, ethylene diamine tetra-acetic acid (EDTA), malonic acid, and oxalic acid. These agents were found to influence the characteristics of the end products, in particular their homogeneity. The phase purity, composition, and microstructure of the polycrystalline samples were studied by thermoanalytical methods (TGADTA), x-ray diffraction (XRD) analysis, IR spectroscopy, and scanning electron microscopy (SEM). From the typical XRD patterns of different synthesis products it is concluded that only the use tartaric acid, 1,2-ethanediol, citric acid, and EDTA yields a single YGG phase.

Leleckaite, Asta; Urbonaite, Sigita; Tõnsuaadu, Kaia; Kareiva, Aivaras

2005-08-01

153

Superhydrophobic sol-gel nanocomposite coatings with enhanced hardness  

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

154

REVIEW ARTICLE: Photopolymerizable sol-gel nanocomposites for holographic recording  

NASA Astrophysics Data System (ADS)

The research into new photosensitive materials with advanced performance for holographic applications is an active branch in material science and photonics, still challenging the field. We proposed a new class of volume hologram recording materials, sol-gel nanocomposites, with important advantages for various holographic applications, including data storage. Here we review several aspects of different types of photosensitive sol-gel glasses that we have developed. Our photopolymerizable glasses exhibit high refractive index modulation, diffraction efficiencies close to the theoretical maxima, along with low scattering and negligible shrinkage. Beside these and other practical advantages discussed in this paper, our recently developed nanocomposite glass incorporating high refractive index species has enabled fundamental studies of new optical phenomena such as the Pendellösung effect, which was observed for the first time in the optical band.

Calvo, María L.; Cheben, Pavel

2009-02-01

155

A Sol-Gel Approach to the Insulation of Rutherford Cables  

SciTech Connect

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 deg. C for 6-12h of the coatings deposited on stainless steel was found to increase the breakdown voltage.

Buta, F. [Global Research and Development, Inc., Columbus, Ohio, 43210 (United States); LASM, MSE, Ohio State University, Columbus, Ohio, 43210 (United States); Hascicek, Y.S.; Arda, L.; Aslanoglu, Z.; Akin, Y. [National High Magnetic Field Laboratory, Tallahassee, Florida, 32310 (United States); Sumption, M.D.; Collings, E.W. [LASM, MSE, Ohio State University, Columbus, Ohio, 43210 (United States)

2004-06-28

156

Improving CdS quantum-dot materials by the sol-gel method  

NASA Astrophysics Data System (ADS)

In this paper we discuss our approaches and results for the preparation of improved semiconductor quantum dot materials by the sol-gel method. By taking advantage of the low- temperature sol-gel route, the nanostructure and optical properties of CdS quantum dots were greatly improved for device applications. Pore-free sodium borosilicate (NBS) glasses and organically modified silicates (ORMOSILs) were used as matrices for the CdS nanocrystallites. Results from both degenerate four-wave mixing and pump-probe techniques indicated large third-order nonlinear responses of the order of 10-6 esu from CdS-doped NBS glasses. By using potassium ion exchange, the first CdS-doped channel waveguides were fabricated in NBS glasses. Propagation of femtosecond laser pulses through the waveguide was investigated. Pulse breakup effect that may be the result of soliton formation was observed in these waveguides. Polydimethylsiloxane (PDMS) was uses as the organic component to modify the silica gel. CdS-doped ORMOSILs derived from the PDMS- TEOS system exhibits improved mechanical property and film-forming ability compared to purely inorganic gels. Both CdS-doped PDMS-TEOS ORMOSILs and NBS glasses were much more resistant to photodarkening than the glasses made by melting. The use of the bifunctional ligand 3-aminopropyltriethoxysilane (APTES) significantly reduced the average particle size and narrowed the size distribution of CdS quantum dots in silica gels and densified NBS glasses.

Li, Chia-Yen; Kao, Yu-Hua; Hayashi, Kazutaka; Takada, Toshimi; MacKenzie, John D.; Kang, Koo I.; Lee, San-Goo; Peyghambarian, Nasser; Yamane, Masayuki; Zhang, Guang-Wen; Najafi, S. Iraj

1994-10-01

157

Radiation-induced densification of sol-gel SnO2:Sb films  

NASA Astrophysics Data System (ADS)

Thin films of tin oxide doped with antimony (25 at.% nominal) were deposited on either silicon wafers or pyrex plates using the sol-gel dip coating technique. The samples processed on Si consist of a single layer of SnO2:/Sb dried at low temperature (150 /°C) for 40 min. Three successive layers, subsequently dried and annealed at 500 /°C for 1 h, were coated on pyrex substrates. Single and multilayered samples were then implanted at room temperature with Xe+ ions in the 1014-1016 cm-2 fluence range. The incident energy (300 keV) was chosen so that the main part of collisional processes occured within the film. The atomic composition and density of the irradiated targets were determined using Rutherford backscattering spectrometry in conjunction with profilometry measurements. Structural informations were obtained from transmission electron microscopy performed on cross-sectional specimen. The results show that ion beam processing is a promising route to densify sol-gel SnO2:/Sb films without overheating the underlying substrate. As an example, the density of a single layer sample irradiated at the highest fluences exceeds 80% of bulk SnO2 density, whereas only 45% of bulk density could be achieved by means of conventional annealing at 500 /°C. A radiation-induced densification is also evidenced in the annealed multideposits. In this case, the whole film is polycrystalline before implantation and becomes amorphous in its densified part.

Canut, B.; Teodorescu, V.; Roger, J. A.; Blanchin, M. G.; Daoudi, K.; Sandu, C.

2002-05-01

158

Intra-grain composition nonuniform barium strontium calcium titanate ceramics by sol-gel pervasion techniques  

NASA Astrophysics Data System (ADS)

The use of ferroelectric ceramics in microwave devices requires that they possess low-loss, frequency-stable and highly tunable properties. The problems of traditional barium strontium calcium titanate ceramics are higher loss and inappropriate work temperature dependence. In this work, a conventional mixed oxide route was used to prepare BaTiO3, SrTiO3 and CaTiO3 precursor powders. The BaTiO3, SrTiO3 and CaTiO3 powders were thoroughly ball mill mixed. They were then added to 5 wt% polyvinyl alcohol and pressed under a uni-axial pressure of 220 MPa into discs of 12 mm diameter. We introduced nano-grains of barium strontium titanate (BST) into the BSCT ceramic by nano-grain pervasion techniques to fabricate compositionally nonuniform BSCT ceramic samples. The nano-particles of BST are prepared with the sol-gel method. The sol-gel was subjected to ultrasonic irradiation and then vacuum methods in order to easily introduce nanoparticles into bulky BSCT. The ceramics do not show a sharp change in the dielectric constant and have a wide range of Curie temperature distribution. This is attributed to the presence of a compositionally nonuniform micro-area in the samples. Compared with uniform-composition BSCT, compositionally nonuniform BSCT has favourable dielectric properties. These results suggest that the compositionally nonuniform BSCT ceramics are promising candidates as tunable microwave elements.

Xu, Honghai; Jin, Dengren; Wu, Wenbiao; Cheng, Jinrong

2009-03-01

159

Sol–gel-derived photonic structures: fabrication, assessment, and application  

Microsoft Academic Search

Sol–gel is a handy, very flexible, and cheap method to fabricate, study, and apply innovative photonic structures. The possibility\\u000a of starting from molecular precursors and elementary building blocks permits to tailor structures at the molecular level and\\u000a to create new materials with enhanced performances. Of specific interest for the study of important physical effects as well\\u000a as for application in

Andrea ChiappiniAlessandro; Alessandro Chiasera; Simone Berneschi; Cristina Armellini; Alessandro Carpentiero; Maurizio Mazzola; Enrico Moser; Stefano Varas; Giancarlo C. Righini; Maurizio Ferrari

160

Hydrolysis catalyst effect on sol–gel silica structure  

Microsoft Academic Search

Silica samples were prepared by the sol–gel process varying the hydrolysis catalyst. The samples were characterized by X-ray diffraction and the radial distribution function was determined (R.D.F.). Fourier transform infrared spectroscopy and thermal analysis were also used. It was found that OH-retention capacity as well as order in the material may be modified with hydrolysis catalysts. When the hydrolysis catalyst

M Asomoza; M. P Dom??nguez; S Sol??s; V. H Lara; P Bosch; T López

1998-01-01

161

Nanostructured energetic materials using sol–gel methodologies  

Microsoft Academic Search

We have utilized a sol–gel synthetic approach in preparing nano-sized transition metal oxide components for new energetic nanocomposites. Nanocomposites of Fe2O3\\/Al(s), are readily produced from a solution of Fe(III) salt by adding an organic epoxide and a powder of the fuel metal. These materials can be processed to aerogel or xerogel monolithic composite solids. High resolution transmission electron microscopy (HRTEM)

T. M. Tillotson; A. E. Gash; R. L. Simpson; L. W. Hrubesh; J. H. Satcher; J. F. Poco

2001-01-01

162

Synthesis of Silicon Carbide Fibers by Sol-Gel Processing  

Microsoft Academic Search

Silica-phenolic resin hybrid fibers with carbon-to-silicon atomic ratios of 2.6 to 5.4 have been prepared from ethanol solutions of tetraethoxysilane, phenolic resins, water, and hydrochloric acid with a tetraethoxysilane- H2O-HCl molar ratio of 1 : 2 : 0.01 by sol-gel processing. The hybrid fibers have been heated at 1500°C in Ar for carbothermal reduction to convert them into silicon carbide

Isao Hasegawa; Toshiyuki Nakamura; Seiji Motojima; Meisetsu Kajiwara

1997-01-01

163

Superhydrophobic sol–gel nanocomposite coatings with enhanced hardness  

Microsoft Academic Search

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

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

2011-01-01

164

Sol-gel laser coatings at CEA Limeil-Valenton  

Microsoft Academic Search

CEA Limeil-Valenton has embarked in a project called 'laser megajoule' (LMJ) consisting of the construction of a 2-MJ\\/500- TW (351-nm) pulsed Nd:glass laser and devoted to inertial confinement fusion research in France. Room temperature and atmospheric pressure deposited sol-gel coatings for antireflective (AR), highly reflective (HR) and polarizer uses, and silicone films for environmental protection have displayed remarkable optical and

Herve G. Floch; Philippe F. Belleville

1997-01-01

165

Sol-Gel Insulation Coatings on Wires for Coil Development  

Microsoft Academic Search

In this study, preparation, structure, morphology and thermal properties of ceramic insulation coating on Monel\\/Fe\\/MgB2 wires, which were fabricated by Hyper Tech Research Inc., using Continuous Tube Forming and Filling (CTFF) process were studied for coil development. Ceramic insulation coatings were prepared by reel-to-reel sol-gel method using solutions of Y and Zr based organometallic compounds. The coating thickness was controlled

L. Arda; C. Boyraz; O. A. Sacli; M. Tomsic; Y. S. Hascicek

2008-01-01

166

Strategies for novel transparent conducting sol–gel oxide coatings  

Microsoft Academic Search

Transparent conducting coatings of doped SnO2 and Zn2SnO4 have been deposited by the sol–gel technique on borosilicate and alumosilicate glass substrates, respectively. As films of SnO2:Sb (ATO) show some intrinsic drawbacks, which are discussed in this report, alternative dopants for SnO2 such as Ta, Nb and W, were examined concerning the electrical and optical properties of the deposited coatings. In

A. Kurz; K. Brakecha; J. Puetz; M. A. Aegerter

2006-01-01

167

Films based on bacteriorhodopsin in sol-gel matrices  

NASA Astrophysics Data System (ADS)

The bacteriorhodopsin film in gelatin matrixes which are used as sensitive elements of integrated optic and fibre-optic sensors of various vapor and gases components will not be able to carry out the chemical control of aqueous solutions. In the given paper the results of technological development of obtaining the bacteriorhodopsin (bR) films in a sol-gel matrix are represented. The films are obtained in a broad thickness range (from 0.5 to 20 microns) with various bR concentrations and photosensitize additives. The optimal technological conditions of obtaining of uniform films with given optical parameters are defined. The surface morphology and cross section of the obtained films was studied using an AFM and SEM. The films have a reasonable surface roughness (~ 100 nm) and a uniform distribution of the purple membrane fragments in the nanostructured sol-gel glass matrix along the films surface and thickness. The transmission spectrums have the characteristic for bR the absorption band, the value of which depends on bR concentration and technological features of the films deposition. The investigated photosensitive properties of the obtained films and influence on them of chemical components of aqueous solutions, allow recommending the thin bR films in sol-gel matrixes for creation of planar waveguides in the role of components of the chemical sensors of liquid solutions.

Korposh, S. O.; Sichka, M. Y.; Trikur, I. I.; Sharkan, Y. P.; Yang, D. H.; Lee, S. W.; Ramsden, J. J.

2005-09-01

168

Sol-Gel Processing of Neodymia-Silica Glass  

NASA Astrophysics Data System (ADS)

Silica glass containing neodymium is a potentially important laser glass because of its low thermal expansion, and high temperature stability. The sol-gel method is highly advantageous in that it permits the uniform distribution of relatively large concentrations of neodymium in a silica host with respect to conventional processing techniques. In the research herein described, the formation of neodymia-silica gels and glasses and the evolution of structure as a function of heat treatment temperature from the liquid state to the glassy state is discussed. A thorough review of the fundamentals of sol-gel processing, many of which were developed as direct result of this research effort, is presented with an emphasis on gel structural evolution. Inasmuch as sol-gel is an aqueous solution based process, the significant problem of hydroxyl contamination is explored. Two methods of OH removal, by chlorination at elevated temperatures and "In Situ dehydroxylization" are examined and compared. The fluorescence and optical properties of neodymia -silica glass is presented and compared with other laser glasses doped with neodymium. For the first time a tentative structural model of the local environment of neodymium in silica glass is proposed.

Pope, Edward John Andrew

169

Functional nucleic acid entrapment in sol-gel derived materials.  

PubMed

Functional nucleic acids (FNAs) are single-stranded DNA or RNA molecules, typically generated through in vitro selection, that have the ability to act as receptors for target molecules (aptamers) or perform catalysis of a chemical reaction (deoxyribozymes and ribozymes). Fluorescence-signaling aptamers and deoxyribozymes have recently emerged as promising biological recognition and signaling elements, although little has been done to evaluate their potential for solid-phase assays, particularly with species made of RNA due to their lack of chemical stability and susceptibility to nuclease attack. Herein, we present a detailed overview of the methods utilized for solid-phase immobilization of FNAs using a sol-gel entrapment method that can provide protection from nuclease degradation and impart long-term chemical stability to the FNA reporter systems, while maintaining their signaling capabilities. This article will also provide a brief review of the results of such entrapment studies involving fluorescence-signaling versions of a DNA aptamer, selected RNA-cleaving deoxyribozymes, and two different RNA aptamers in a series of sol-gel derived composites, ranging from highly polar silica to hydrophobic methylsilsesquioxane-based materials. Given the ability to produce sol-gel derived materials in a variety of configurations, particularly as thin film coatings on electrodes, optical fibers, and other devices, this entrapment method should provide a useful platform for numerous solid-phase FNA-based biosensing applications. PMID:24025165

Carrasquilla, Carmen; Brennan, John D

2013-09-08

170

Sol-gel optical coatings for lasers, 3  

SciTech Connect

The planned megajoule-class neodymium-glass laser system will be the world`s largest. The proposed CEL-V design, based on the use of 240 beams, will use 50--150 times more optical material than did Phebus. Almost 10,000 m{sup 2} of coated area are required for optical coatings; this is a factor of almost 500 increase over Phebus. Lens, flashlamp, blastshield, harmonic converter, debris shield, window and cavity-end mirror coatings by the sol-gel process represent >96% of the entire coated area. The remaining <4% are high-rejection-ratio polarizers, pick-off cavity mirrors and transport mirrors. Cost estimates show that, for coating deposition, the sol-gel technique provides considerable saving compared to the more conventional e-beam deposition technique. Highly reflective and polarizing sol-gel-derived optical coatings have been prepared and tested for the proposed French megajoule neodymium-glass laser. Laser damage studies are reported here.

Floch, H.G.; Belleville, P.F.; Priotton, J.J. [CEA-Centre d`Etudes de Limeil-Valenton, Villeneuve-Saint Georges (France). Dept. of Lasers and Plasma Physics; Pegon, P.M.; Dijonneau, C.S.; Guerain, J. [Reosc Optique-Groupe SFIM, Ballainvilliers (France)

1995-12-01

171

Nanofiltration in non-aqueous solutions by porous silica–zirconia membranes  

Microsoft Academic Search

Porous membranes having various average pore sizes, ranging from 1 to 4nm, were prepared from silica–zirconia composite colloidal sols by sol–gel processes, and were used for nanofiltration (NF) experiments in non-aqueous solutions of ethanol and methanol. Silica–zirconia membranes, which were tested in pure alcohol solutions for the first time after the preparation of the membrane, showed a gradual decrease in

Toshinori Tsuru; Takashi Sudoh; Tomohisa Yoshioka; Masashi Asaeda

2001-01-01

172

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

Microsoft Academic Search

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

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

2010-01-01

173

Solventless sol-gel chemistry through ring-opening polymerization of bridged disilaoxacyclopentanes  

SciTech Connect

Disilaoxacyclopentanes have proven to be excellent precursors to sol-gel type materials. These materials have shown promise as precursors for encapsulation and microelectronics applications. The polymers are highly crosslinked and are structurally similar to traditional sol-gels, but unlike typical sol-gels they are prepared without the use of solvents and water, they have low VOC's and show little shrinkage during processing.

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.

2000-04-04

174

Morphology evolution of ZrB2 nanoparticles synthesized by sol-gel method  

NASA Astrophysics Data System (ADS)

Zirconium diboride (ZrB2) nanoparticles were synthesized by sol-gel method using zirconium n-propoxide (Zr(OPr)4), boric acid (H3BO3), sucrose (C12H22O11), 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. C12H22O11 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 ZrB2 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 ZrB2 were gradually fused together to evolve into a particle chain, finally into a rod-like shape. These crystalline nature of ZrB2 related to the gelation temperature obeyed the “oriented attachment mechanism” of crystallography.

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

2011-08-01

175

Magnetic properties of sol-gel derived Gd2O3 nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline Gd2O3 particles of average particle size 25 nm (p25) and 18 nm (p18) are prepared through sol-gel route. Magnetization measurements in both samples show a linear variation of ?-1 with T having two different slopes in the temperature range 30 K- 260 K. In the temperature range 135 K <= T <= 260 K (TR1) the effective moment (?eff) per Gd3+ is estimated to be 7.70 ?B and 7.56 ?B whereas, in the temperature range 30 K <= T <= 135 K (TR2) they are estimated as 7.92 ?B and 7.79 ?B for p25 and p18, respectively. The enhancement of ?eff in the TR2 region may be related with the clustering of spins. Below 30 K, ?-1 deviates from the linearity. At 5K magnetization curve displays superparamagnetic like characteristic features.

Ray, R.; Biswas, Sumita; Das, S.; Patra, M.

2012-06-01

176

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

177

Sol-gel processes and materials. (Latest citations from the Aerospace database). Published Search  

SciTech Connect

The bibliography contains citations concerning design and development of sol-gel processes and sol-gel derived materials. Sol-gel derived materials include protective and transparent films, ceramic coatings, nanocomposites and microcomposites, porous and dense composites, fiber reinforced composites, oxides, and ductile ceramics. Topics include preparation of high temperature superconducting oxides and films, glass-ceramic composites and ceramic matrix composites for high temperature applications, sol-gel processes for advanced ceramics, coatings on semiconductors, infrared optical coatings, and coatings on carbon/carbon composites. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1994-11-01

178

Sol-gel processes and materials. (Latest citations from the Aerospace database). Published Search  

SciTech Connect

The bibliography contains citations concerning design and development of sol-gel processes and sol-gel derived materials. Sol-gel derived materials include protective and transparent films, ceramic coatings, nanocomposites and microcomposites, porous and dense composites, fiber reinforced composites, oxides, and ductile ceramics. Topics include preparation of high temperature superconducting oxides and films, glass-ceramic composites and ceramic matrix composites for high temperature applications, sol-gel processes for advanced ceramics, coatings on semiconductors, infrared optical coatings, and coatings on carbon/carbon composites. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1994-01-01

179

Titanium vacancy defects in sol gel prepared anatase  

NASA Astrophysics Data System (ADS)

Rietveld refinement of powder X-ray diffraction data for nanocrystalline anatase samples prepared by different sol gel methods shows that the samples contain high concentrations (? 20%) of titanium vacancies, the levels of which decrease with increasing crystallite size. Debye function modelling of anatase clusters with different well-defined sizes, shapes and stoichiometries confirmed that the titanium vacancy concentrations obtained from the Rietveld refinements are correct. However, the Debye modelling showed that for nanocrystals smaller than ˜4 nm, the Rietveld modelling gives artificially high cell parameters. Density function theory calculations show that the titanium vacancies are stable defects when the vacancy sites are charge-balanced by incorporation of protons.

Grey, Ian. E.; Wilson, Nicholas C.

2007-02-01

180

Dehydration and crystallization process in sol-gel zirconia  

Microsoft Academic Search

Sol-gel zirconia was characterized using high-resolution thermogravimetry (Hi-Res TG) and differential scanning calorimetry\\u000a (DSC) and compared with X-ray diffraction, Raman scattering, and UV-Vis spectroscopy. ZrO2-x(OH)2x·yH2O annealed below 400°C show typical behavior of amorphous material. As the annealing temperature is increased, the tetragonal\\u000a and monoclinic phases crystallize. Typical Hi-Res TG curve shows that the samples are continuously dehydrated in a long

M. Picquart; T. López; R. Gómez; E. Torres; A. Moreno; J. Garcia

2004-01-01

181

Sol-Gel Processed Conjugated Polymers for Optical Waveguides  

Microsoft Academic Search

Novel sol-gel processed poly(l,4-phenylene vinylene) (PPV) and poly(2,5-disubstituted-l,4-phenylene vinylene)\\/silica composites were prepared by a soluble precursor technique. The two PPV derivatives included in this study were poly(2-bromo-5-methoxy-l,4-phenylene vinylene) and poly(2-butoxy-5-methoxy-1,4-phenylene vinylene). The spectral characteristics of these materials have been investigated using UV-visible and FT-IR spectroscopy. The densification process was studied by differential scanning calorimetry and thermal gravimetric analyzer. The third-order

Kwang-Sup Lee; Chichang J. Wung; Paras N. Prasad; Jong-Chul Kim; Chi Kyun Park; Jung-Il Jin; Hong-Ku Shim

1993-01-01

182

Synthesis of silicon carbide fibers by sol-gel processing  

Microsoft Academic Search

Silica-phenolic resin hybrid fibers with carbon-to-silicon atomic ratios of 2.6 to 5.4 have been prepared from ethanol solutions\\u000a of tetraethoxysilane, phenolic resins, water, and hydrochloric acid with a tetraethoxysilane-H2O?HCl molar ratio of 1:2:0.01 by sol-gel processing. The hybrid fibers have been heated at 1500C in Ar for carbothermal reduction\\u000a to convert them into silicon carbide fibers. The effects of the

Isao Hasegawa; Toshiyuki Nakamura; Seiji Motojima; Meisetsu Kajiwara

1997-01-01

183

Sol–gel combustion synthesis of BNBT powders  

Microsoft Academic Search

Ba-modified bismuth sodium titanate with composition 0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3 (BNBT) was prepared by a citrate nitrate sol–gel combustion method. The sol was obtained using barium acetate, bismuth nitrate,\\u000a sodium nitrate and a peroxo-citrate complex of titanium isopropoxide as starting precursors. Various molar ratios of citrate\\/nitrate\\u000a (C\\/N) were considered for the sol production. The corresponding gels were fired at different temperatures (300, 400,

Elisa Mercadelli; Carmen Galassi; Anna Luisa Costa; Stefania Albonetti; Alessandra Sanson

2008-01-01

184

Guided wave measurements for characterization of sol-gel layers  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

185

Manipulation and characterization of thin-film interfacial chemistry: Sol-gel deposition and single molecule tracking experiments  

NASA Astrophysics Data System (ADS)

Single molecule trajectories of 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbo - cyanine perchlorate (DiI) fluorophores diffusing on planar supported 1,2-dimyristoyl-snglycero- 3-phosphocholine (DMPC) lipid bilayers imaged through total internal reflection fluorescence (TIRF) microscopy at different temperatures are investigated. The spatial resolution limit for detecting molecular motion is evaluated by characterizing the apparent motion which arises from the limited signal-to-noise ratio (S/N) of imaged and simulated stationary DiI molecules. Statistical criteria for reliably distinguishing molecular motion from stationary molecules using F-test statistics, including the computation of local signal-to-noise ratios are then established and used for reliably detecting subdiffraction motion of DiI molecules on DMPC. The same single molecule tracking concept is used in investigating the temperature dependence of subdiffraction diffusional confinement of single Rhodamine 6G molecules in polymer brushes of poly (N-isopropylacrylamide), pNIPAAm, above and below its lower critical solution temperature (LCST) of 32°C. Reliably distinguishing subdiffraction molecular motion from stationary events is crucial in validating the application of single molecule tracking experiment in probing nanometersized hydrophobic environments of polymer structure. A versatile and rapid sol-gel technique for the fabrication of high quality one-dimensional photonic bandgap materials was developed. Silica/titania multilayer materials are fabricated by a sol-gel chemistry route combined with dip-coating onto planar or curved substrate. A shock-cooling step immediately following the thin film heat-treatment process is introduced. The versatility of this sol-gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties. Measured optical properties show good agreement with theoretical simulations confirming the high quality of these sol-gel fabricated optical materials. Finally, magnetic functionalization studies of sol-gel derived Co-ion doped titania thin films using superconducting quantum interference device (SQUID) magnetometry and an attempt to measure their magneto-optical properties using a home-built Faraday rotation setup are discussed. The experimental limitations in reliably measuring magnetization responses of these thin films are introduced and discussed in detail. The summary and outlook chapters summarize the scientific significance of each research project and briefly introduce ongoing research based on the work and the results presented in this dissertation.

Barhoum, Moussa

186

Preparation of superhydrophobic surface with a novel sol-gel system  

NASA Astrophysics Data System (ADS)

Sol-gel method is a simple and cheap way to prepare superhydrophobic coatings or films, however, most of the researches on sol-gel focus on silica or ZnO sol-gel. The present paper proposes a novel sol-gel which is made from hydrolysis and condensation of the by-product of polymethylhydrosiloxane (PMHS) reacting with ?-aminopropyltriethoxysilane (KH550). The mechanism of formation of the by-product and the sol-gel is discussed and the by-product is characterized by FT-IR. The mass ratio of KH550/PMHS of the sol-gel influences the water contact angle (WCA) and water sliding angle (WSA) of the film made of spraying the sol-gel to microscope glass. When the mass ratio of KH550/PMHS of the sol-gel reaches 0.25, WCA of the corresponding film is 157° and WSA of it is less than 1°. The mechanism of formation of the sol-gel is discussed, and the size of the sol-gel is characterized by polarization microscope as well. The morphology of the film made of the sol-gel is analyzed by means of scanning electron microscope (SEM). It was found that the diameter of the particle of the superhydrophobic film is about 40 ?m, nevertheless, from the larger magnification picture, the particle is found to be composed of micro-balls whose diameter is about 2 ?m, and the micro-ball is composed of nano-sphere whose diameter is less than 200 nm.

Su, Dong; Huang, Chengya; Hu, You; Jiang, Qiangwei; Zhang, Long; Zhu, Yunfeng

2011-11-01

187

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

NASA Astrophysics Data System (ADS)

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.

Hales, Matthew; Martens, Wayde; Steinberg, Theodore

188

New photonics media prepared by sol-gel process  

NASA Astrophysics Data System (ADS)

It is recognized that the earliest and most prodigious development in photonics technology will be in the area of second-order nonlinear optical processes: second-harmonic generation and electro-optic modulation. Photonics applications will undoubtedly involve an integration of fast and reliable high-speed optical crossbar switches, electric field sensing devices, and beam alignment of read-write heads for optical data storage in optical computers. The requirements for such devices are very rigorous, and their development relies on employing photonics materials whose linear and nonlinear optical properties can be engineered. There are several organic materials that are being developed into viable devices due to the fact that their (chi) (2) nonlinearities are much higher than those of existing dielectrics. The most recent materials applied to integrated optics have been the sol-gel processed glasses and glass/polymer nanocomposites which have the inherent advantages of being more easily processed and are cost effective. We report in this paper the recent developments of studies involving linear and nonlinear optical properties of some novel sol-gel processed inorganic oxides/organic polymer composites for nonlinear optics and photonics applications.

Burzynski, Ryszard; Casstevens, Martin K.; Zhang, Yue; Zieba, Jaroslaw W.; Prasad, Paras N.

1993-04-01

189

Electrospun sol-gel fibers for fluorescence-based sensing  

NASA Astrophysics Data System (ADS)

Fluorescence based biosensors have the ability to provide reliable pathogen detection. However, the performance could be improved by enhancing the effective surface area of the biosensor. We report on a new nanofibrous fluorescencebased biosensor, whereas a sol-gel platform mesh was constructed by utilizing electrospinning techniques. Furthermore, incorporating cetyltrimethylammonium bromide (CTAB) and conducting pore-forming techniques resulted in a high surface area material suitable for biosensor immobilization. The biosensor was designed to detect Helicobacter hepaticus bacterium by sandwiching the pathogen between two antibodies, one labeled with Alexa Fluor 546 fluorescent dye and the other with 20nm Au nanoparticles. In the presence of pathogen, the close proximity of Au nanoparticles quenched the Alexa Fluor fluorescence, suggesting that the electrospun fiber platforms are suitable for sensing H. Hepaticus. Additionally, sol-gel fibers used as biosensor platform have the added benefit of increased immobilization, as fluorescence intensity from immobilized biosensors is 8.5x106 cps higher on fibers than on a flat, non-porous substrate.

Memisevic, Jasenka; Riley, Lela; Grant, Sheila A.

2009-05-01

190

Nanostructured energetic materials derived from sol-gel chemistry  

SciTech Connect

Initiation and detonation properties are dramatically affected by an energetic material's microstructural properties. Sol-gel chemistry allows intimacy of mixing to be controlled and dramatically improved over existing methodologies. One material goal is to create very high power energetic materials which also have high energy densities. Using sol-gel chemistry we have made a nanostructured composite energetic material. Here a solid skeleton of fuel, based on resorcinol-formaldehyde, has nanocrystalline ammonium perchlorate, the oxidizer, trapped within its pores. At optimum stoichiometry it has approximately the energy density of HMX. Transmission electron microscopy indicated no ammonium perchlorate crystallites larger than 20 nm while near-edge soft x-ray absorption microscopy showed that nitrogen was uniformly distributed, at least on the scale of less than 80 nm. Small-angle neutron scattering studies were conducted on the material. Those results were consistent with historical ones for this class of nanostructured materials. The average skeletal primary particle size was on the order of 2.7 nm, while the nanocomposite showed the growth of small 1 nm size crystals of ammonium perchlorate with some clustering to form particles greater than 10 nm.

Simpson, R L; Tillotson, T M; Hrubesh, L W; Gash, A E

2000-03-15

191

Optical materials by a modified sol-gel nanoparticle process  

NASA Astrophysics Data System (ADS)

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.

Schmidt, Helmut K.; Mennig, Martin

2000-05-01

192

Exact kinetics of the sol-gel transition  

NASA Astrophysics Data System (ADS)

The formation of a gel in a disperse system wherein binary coagulation alone governs the temporal changes of particle mass spectra is studied under the assumption that the coagulation kernel is proportional to the product of masses of coalescing particles. This model is known to reveal the sol-gel transition, i.e., the formation of one giant cluster with the mass comparable to the total mass of the whole system. This paper reports on the exact solution of this model for a finite total mass of the coagulating system. The evolution equation for the generating functional defining all properties of coagulating systems is solved exactly for this particular kernel. The final output is the exact expression for the single-particle mass spectrum as a function of time. The analysis of the spectrum in the thermodynamic limit shows that after a critical time a giant single particle (the gel) appears. Although the concentration of this giant gel particle is zero in the thermodynamic limit, it actively interacts with smaller particles “eating” them and thus growing in mass. Special attention is given to the transition point, where the gel is appearing. It is demonstrated that the sol-gel transition reminds the second-order phase transition. The time dependencies of the gel mass, the number concentration, and the second moment of the particle mass spectrum are found.

Lushnikov, A. A.

2005-04-01

193

Study of silica sol-gel materials for sensor development  

NASA Astrophysics Data System (ADS)

Silica sol-gel is a transparent, highly porous silicon oxide glass made at room temperature by sol-gel process. The name of silica sol-gel comes from the observable physical phase transition from liquid sol to solid gel during its preparation. Silica sol-gel is chemically inert, thermally stable, and photostable, it can be fabricated into different desired shapes during or after gelation, and its porous structure allows encapsulation of guest molecules either before or after gelation while still retaining their functions and sensitivities to surrounding environments. All those distinctive features make silica sol-gel ideal for sensor development. Study of guest-host interactions in silica sol-gel is important for silica-based sensor development, because it helps to tailor local environments inside sol-gel matrix so that higher guest loading, longer shelf-life, higher sensitivity and faster response of silica gel based sensors could be achieved. We focused on pore surface modification of two different types of silica sol-gel by post-grafting method, and construction of stable silica hydrogel-like thin films for sensor development. By monitoring the mobility and photostability of rhodamine 6G (R6G) molecules in silica alcogel thin films through single molecule spectroscopy (SMS), the guest-host interactions altered by post-synthesis grafting were examined. While physical confinement remains the major factor that controls mobility in modified alcogels, both R6G mobility and photostability register discernable changes after surface charges are respectively reversed and neutralized by aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTES) grafting. The change in R6G photostability was found to be more sensitive to surface grafting than that of mobility. In addition, silica film modification by 0.4% APTS is as efficient as that by pure MTES in lowering R6G photostability, which suggests that surface charge reversal is more effective than charge neutralization in disrupting R6G/silica attraction. Similar post-grafting method was applied to highly hydrated silica hydrogel monoliths. Rhodamine 6G (R6G) and fluorescein (Fl) molecules were used as probes to monitor the surface modification inside silica hydrogel by measuring anisotropy values of doped dyes. Due to the larger pore sizes, pore surface modification inside hydrogel was more effective than in alcogel. Surface modification by chemical reactions of 3-Aminopropyltrimethoxysilane (APTS) and methyltriethoxysilane (MTES) showed dramatic effect on guest molecule mobility, whereas surface modification by physical method, that is to increase ionic strength by using 1.0 M sodium chloride or to neutralize pore surfaces by adding pH 2.0 hydrochloric acid, barely showed any effect. Charge-reversal by APTS is a more effective way to modify pore surfaces in hydrogel than hydrophobic capping from MTES. The ease of tracking surface modification inside hydrogel by simply locating R6G dye band, and the negligible pore fluid effect on R6G in modified hydrogel makes R6G a better probe than Fl to monitor the pore surface modification process in silica hydrogel monoliths. During the study of post-grafting on silica alcogel thin film, a new approach to produce stable silica hydrogel-like thin films was discovered. Homogeneous thin film hydrogel-like samples with thickness between 100 nm and 300 nm were produced, and they showed a very hydrophilic surface, high dye loading capacity, and the support of molecular diffusion. The reactive stage of starting silica gel matrix was elongated by increasing environmental humidity, the reproducibility of sample preparation was greatly improved by controlling environmental humidity, and the dye loading capacity of samples was improved more than ten times by using phosphate buffer solutions (PBS). The concentration of R6G trapped inside hydrogel-like thin film could reach as high as 900 times of its saturated aqueous solution. Dye encapsulation can simply be accomplished by dipping a chemically reactive alcogel thin film into a dye-doped buffer

Lei, Qiong

194

Sol-gel optical coatings for lasers, 2  

SciTech Connect

There are three basic types of antireflective (AR) coatings. The first is a single-layer coating in which the coating index is equal to the square root of the index of the substrate, assuming air is the external medium. The second type is a system of two or more layers of different indexes. The third type is a graded-index system, where the index is uniformly and continuously graded from the substrate to the external medium. Low reflection ranges from narrow for the single-layer to broad for the graded-layer and multilayered with a large number of layers. Four types of sol-gel AR coatings have been developed at CEL-V. They are based on single-layer or multilayer designs. They consist mainly of amorphous silica in the polymeric and/or colloidal state, combined in certain cases with other metallic oxides, binders, fillers, hydrophobic and lubricating agents, and adhesion promoters. These antireflective sol-gel-derived optical coatings have been prepared and tested for the proposed French megajoule neodymium-glass laser.

Floch, H.G.; Belleville, P.F.; Priotton, J.J. [CEA-Centre d` Etudes de Limeil-Valenton, Villeneuve-Saint Georges (France). Dept. of Lasers and Plasma Physics; Pegon, P.M.; Dijonneau, C.S.; Guerain, J. [Reosc Optique-Groupe SFIM, Ballainvilliers (France)

1995-11-01

195

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

SciTech Connect

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.

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

196

Sol–gel prepared MoO 3–WO 3 thin-films for O 2 gas sensing  

Microsoft Academic Search

Oxygen gas sensing properties of molybdenum trioxide and tungsten trioxide (MoO3–WO3) mixed metal oxide thin-films are investigated. Various MoO3–WO3 ratio thin-film samples are deposited onto silicon (100) and sapphire substrates via the sol–gel route. SEM analysis showed the presence of MoO3 orthorhombic phase, abating as WO3 dominated the mixed system. MoO3–WO3 sensors exhibited a linear response to O2 concentrations varying

K Galatsis; Y. X Li; W Wlodarski; K Kalantar-zadeh

2001-01-01

197

Calcium and phosphate adsorption as initial steps of apatite nucleation on sol-gel-prepared titania surface.  

PubMed

Titania powders have been prepared by the sol-gel route from Ti (IV) ethoxide under acidic conditions. Adsorption experiments of calcium and phosphate ions on gel-derived titania suspensions were performed to suggest a likely initial step of apatite growth on its surface. Experiments were performed as a function of time and pH at 37 degrees C with and without NaCl present in the suspensions. Also, zeta (zeta) potential experiments were performed to determine the kind of calcium adsorption. Results suggest that, apparently, calcium and phosphate adsorption can act as two different initial steps for apatite growth. PMID:12483705

Coreño, Juan; Martínez, Antonia; Coreño, Oscar; Bolarín, Ana; Sánchez, Félix

2003-01-01

198

Self-aligned magnetic dipole moments of Fe 2O 3 formed within sol–gel matrix  

Microsoft Academic Search

Fe2O3 nanoparticles were formed within SiO2 framework via a sol–gel co-precipitation synthesis route. Various weight percentages of Fe2O3 in the composites ranging from 8.6 to 52.8wt.% were formulated. X-ray diffraction and Raman spectra indicated the formation of ?-phase Fe2O3 nanoparticles. EPR spectra of the Fe2O3 nanocomposites were found to depend significantly on the weight composition of Fe2O3. The composite with

Xiaoming Zhang; Haiquan Guo; Ning Chi; Shunchin C. Wang; Nan-Loh Yang; Daniel L. Akins

2006-01-01

199

Composition and magnetic studies of ultrafine Al-substituted Sr hexaferrite particles prepared by citrate sol-gel method  

Microsoft Academic Search

Ultrafine aluminum-substituted strontium hexaferrite particles have been prepared via citrate sol-gel route. Gels were synthesized with molar ratios [Al3+]:[Fe3+] of 0.4:11.6, 1:11, 1.5:10.5 and 2:10 and the ferrite particles were obtained by annealing the gels at 950 °C for 2 and 24h. Electron energy dispersive X-ray spectroscopy (EDX) verified the presence of Al in the substituted samples. X-ray diffraction (XRD)

Tran Thi Viet Nga; Nguyen Phuc Duong; Than Duc Hien

200

In situ synthesis of terbium-benzoic acid complex in sol–gel derived silica by a two-step sol–gel method  

Microsoft Academic Search

Terbium complexes with benzoic acid and its derivatives o-hydroxybenzoic acid and p-hydroxybenzoic acid were in situ synthesized in sol–gel derived silica matrix via a two-step sol–gel process. The formation process of the complex was characterized by fluorescence spectra, absorption spectra and IR spectra. The gels that contain in situ synthesized complexes exhibit the characteristic emission bands of terbium ion. The

F. Lianshe; Meng Qingguo; Zhang Hongjie; Wang Shubin; Yang Kuiyue; N. Jiazuan

2000-01-01

201

Preparation and catalytic performance of lipases encapsulated in sol-gel materials.  

PubMed

Three kinds of lipases (from Candida antarctica, Pseudomonas cepacia, and Pseudomonas fluorescens) were encapsulated in inorganic matrices by the sol-gel method in order to synthesize chiral compounds by kinetic resolution. Sol-gel lipases prepared with vinyltriethoxysilane had higher hydrolysis activity for 2-octyl acetate than those with other silane precursors: tetramethoxysilane, methyltrimethoxysilane, and propyltrimethoxysilane. PMID:11866115

Kato, Katsuya; Gong, Yuefa; Saito, Takao; Yokogawa, Yoshiyuki

2002-01-01

202

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

Microsoft Academic Search

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

C. T. Chu; Jay Chu; Haixing Zheng

1995-01-01

203

Low-temperature thermal properties of a sol-gel glass  

Microsoft Academic Search

The thermal conductivity and specific heat of an uncompacted sol-gel glass have been measured over the temperature range T~=0.1-10 K. Relative to the compacted product, vitreous silica, the specific heat attributed to two-level states at T1 K, phonon transport appears to be limited by scattering from pores intrinsic to the sol-gel product.

J. M. Grace; A. C. Anderson

1986-01-01

204

Nanoporous carbon synthesized from sol–gel template for adsorbing gibberellic acid in aqueous solution  

Microsoft Academic Search

A novel method, based on dynamic carbonization and silica template formed by sol–gel, was developed to prepare nanoporous carbon materials with tailored pore structures. The effects of the sol–gel reaction and carbonization process on the final nanoporous carbon product were investigated by pore features such as specific surface area, the total pore volume, and pore size distribution, which were systemically

Jin Li; Jin-Tong Xia; Hong-Bo Liu; Jiao-Lian He; Jun-Hua Zhang

2011-01-01

205

Encapsulation of Proteins in Bulk and Thin Film Sol-Gel Matrices  

Microsoft Academic Search

This paper considers the nature of the interactions between the sol-gel derived inorganic matrix and a specific biomolecule, cytochrome c. Optical absorption and impedance spectroscopies are used to characterize the influence of synthesis conditions on the protein's stability and conformation within the silica matrix. In some instances, encapsulation within the sol-gel matrix provides stabilization. For example, protein denaturation is reversible

B. C. Dave; J. M. Miller; B. Dunn; J. S. Valentine; J. I. Zink

1997-01-01

206

Synthesis, functionalisation and characterisation of mesoporous materials and sol–gel glasses for applications in catalysis, adsorption and photonics  

Microsoft Academic Search

In this review, synthesis and functionalisation approaches for ordered mesoporous materials and sol–gel glasses are described. Catalytic and adsorption applications are emphasised for the ordered mesoporous materials, while optical applications are the focus for sol–gel glasses.

Gisle Øye; Wilhelm R. Glomm; Torbjørn Vrålstad; Sondre Volden; Heléne Magnusson; Michael Stöcker; Johan Sjöblom

2006-01-01

207

Photochemical Enzyme Co-Factor Regeneration: Towards Continuous Glutamate Monitoring with a Sol-Gel Optical Biosensor.  

National Technical Information Service (NTIS)

Sol-gel encapsulation has recently surfaced as a successful approach to biomolecule immobilization. Proteins, including enzymes, are trapped in the pores of the sol-gel derived glass while retaining their spectroscopic properties and biological activity. ...

A. J. Tobin B. Dunn J. I. Zink J. L. Rickus

2002-01-01

208

Epitaxial growth of La 2Zr 2O 7 thin films on rolled Ni-substrates by sol–gel process for high T c superconducting tapes  

Microsoft Academic Search

A solution process was used to grow epitaxial La2Zr2O7 (LZO) buffer layers on roll-textured Ni (100) substrates to produce YBa2Cu3O7?? (YBCO)-coated conductors. The LZO precursor solution was prepared by an all alkoxide sol–gel route using mixed metal methoxyethoxides in 2-methoxyethanol. The partially hydrolyzed solution was either spin-coated or dip-coated onto the textured Ni substrates. The amorphous thin film was then

T. G Chirayil; M. Paranthaman; D. B Beach; D. F Lee; A. Goyal; R. K Williams; X. Cui; D. M Kroeger; R. Feenstra; D. T Verebelyi; D. K Christen

2000-01-01

209

Magnetic properties of As2O3- and Sb2O3-doped BaM hexagonal ferrites prepared by the sol-gel method  

Microsoft Academic Search

Ba-M hexagonal ferrites with As2O3 and Sb2O3 doping have been prepared in the composition series BaO.(6 - x)Fe2O3 .xM2O3 (M = As or Sb) with 0 <= x <= 0.4 by the sol-gel route. The precursor sol is prepared by using barium acetate and the chlorides of iron and arsenic\\/antimony respectively. Pellitized powders of these hexaferrites are sintered in the

P. Brahma; Anit K. Giri; D. Chakravorty; M. Roy; D. Bahadur

1992-01-01

210

Titanium and iron oxides produced by sol–gel processing of [FeCl{Ti 2(OPr i ) 9}]: structural, spectroscopic and morphological features  

Microsoft Academic Search

The first structurally characterised titanium and iron isopropoxide, [FeCl{Ti2(OPri)9}] (1), has been used as a single-source precursor for TiO2\\/Fe2TiO5 composites prepared by the sol–gel route. Two distinct hydrolysis and condensation conditions were employed, followed by drying and thermal treatment up to 1000°C. Product composition and oxide phase transitions were characterised by powder X-ray diffractometry and Raman, electron paramagnetic resonance, Mössbauer

Pedro H. C Camargo; Giovana G Nunes; Geraldo R Friedermann; David J Evans; G. Jeffery Leigh; Germano Tremiliosi-Filho; Eduardo L de Sá; Aldo J. G Zarbin; Ja??sa F Soares

2003-01-01

211

Titanium vacancy defects in sol-gel prepared anatase  

SciTech Connect

Rietveld refinement of powder X-ray diffraction data for nanocrystalline anatase samples prepared by different sol-gel methods shows that the samples contain high concentrations ({<=} 20%) of titanium vacancies, the levels of which decrease with increasing crystallite size. Debye function modelling of anatase clusters with different well-defined sizes, shapes and stoichiometries confirmed that the titanium vacancy concentrations obtained from the Rietveld refinements are correct. However, the Debye modelling showed that for nanocrystals smaller than {approx}4 nm, the Rietveld modelling gives artificially high cell parameters. Density function theory calculations show that the titanium vacancies are stable defects when the vacancy sites are charge-balanced by incorporation of protons. - Graphical abstract: Relaxed structure from DFT modelling of anatase containing one titanium vacancy and four protons.

Grey, Ian.E. [CSIRO Minerals, Bayview Avenue, Clayton, Vic., 3169 (Australia)], E-mail: ian.grey@csiro.au; Wilson, Nicholas C. [CSIRO Minerals, Bayview Avenue, Clayton, Vic., 3169 (Australia)

2007-02-15

212

Controlled deposition of sol-gel sensor material using hemiwicking  

NASA Astrophysics Data System (ADS)

Optical sensors are fabricated by depositing liquid sol-gel sensor material on a polycarbonate surface, which has been decorated with arrays of periodic micropillars. Using the principle of hemiwicking, the liquid material is spread, guided by the surface structures, to homogeneously fill the volume between the surface structures and form a liquid film with a thickness determined by the height of the micropillars. After evaporation of solvents, a uniform layer of sensor material resides on the surface. This fabrication method enables easy and reproducible deposits of isolated spots of different sensor materials of precise thickness to be made on plastic surfaces, and it provides an improved method for fabricating cheap optical sensors integrated in disposable lab containers.

Mikkelsen, Morten Bo; Marie, Rodolphe; Hansen, Jan H.; Wencel, Dorota; McDonagh, Colette; Nielsen, Hans Ole; Kristensen, Anders

2011-11-01

213

Eu2+ doped calcium aluminate coatings by sol gel methods  

NASA Astrophysics Data System (ADS)

Eu2+ doped calcium aluminate coatings were prepared by the dip- and spin-coating methods on ?-alumina substrates. This kind of persistent luminescent coatings may replace the luminous paints used in many applications. If sol gel methods are used the expense of preparing the coatings is relatively low. Annealing at 1050 °C yielded the CaAl2O4:Eu2+ coatings with similar luminescence and thermoluminescence properties than those of the CaAl2O4:Eu2+ powders. At higher annealing temperatures, CaAl4O7 and CaAl12O19 were formed due to the diffusion of alumina from the substrate. The persistent luminescence was, however, relatively weak and thus more work is needed to optimize the multitude of parameters affecting the properties of the coatings.

Aitasalo, T.; Hölsä, J.; Jungner, H.; Lastusaari, M.; Niittykoski, J.; Saarinen, J.

2005-07-01

214

Low-index electro-optic sol-gel materials  

NASA Astrophysics Data System (ADS)

Polymeric electro-optic materials have made significant progress in increasing electro-optic co-efficient, enhancing temporal stability, and lower optical loss at operating wavelength. To fully realize the electro-optic activity in a waveguide device, appropriate cladding materials need to be designed carefully and a compatible fabrication process should be developed accordingly, which has been challenging and tedious. It would be desirable if glass-based optical fiber or silica substrate can be utilized as parts of device materials. The challenge is to match the relatively lower refractive index of fiber and silica substrates. Thus, a low refractive (~1.44) of electro-optic material was designed. The efforts include the synthesis and characterization of the low index host materials via sol-gel process and silanization of a chromophore with large hyperpolarizability. In this study, an electro-optic sol-gel material with a refractive index ~1.44 at the wavelength of 1.55 ?m was developed. It was highly processible and compatible with glass-based fiber or silica-based materials. An interdigitated electrode configuration is designed and a substrate with such a configuration was fabricated. Combined with the in-situ SHG monitoring setup, poling process can be readily monitored and optimized. The r33 obtained at the wavelength of 1.3 ?m is 19 pm/V. Thus, it becomes possible to design optical devices using glass-based fiber or silica substrate as part of the device structure, which could simplify the material and process development.

Jin, Danliang; Huang, Diyun; Condon, Stephen; Guan, HannWen; Cong, Shuxin; Barklund, Anna; Dinu, Raluca

2005-12-01

215

Composite sol-gel process for photocatalytic titanium dioxide  

NASA Astrophysics Data System (ADS)

Photocatalytic TiO2 decomposes organic and inorganic pollutants upon irradiation with UV light. TiO2 thin films and powder suspensions are used for purification treatments, but small surface area of TiO2 films, and difficult filtration of powders are the two major drawbacks in application of photocatalytic TiO2. The major objective of this work was to develop a novel process to combine the thin film coatings and the fine (sub-micron) powder anatase TiO2 to provide high photocatalytic efficiency thick films and self-supported membranes. The microstructural properties and photocatalytic efficiency of the developed materials were characterized and compared with that of the conventional TiO2 coatings and powders. Photocatalytic activity of CSG TiO 2 was measured through the ability to decompose organic compounds (trichloroethane, dioxane, toluene), as well as to destroy bacteria. The major achievement of this work is the development of a process wherein structurally sound, thick films and membranes of CSG anatase photocatalytic TiO2 can be produced in reproducible way. A novel method for the synthesis of monodispersed anatase TiO2 microspheres through colloidal precipitation has also been established. The microspheres were used as filler TiO2 in the composite microstructure, bonded with sot-gel derived TiO2, to produce the composite sol-gel (CSG) TiO2. A sol-gel-assisted sintering model for the CSG thick films and self-supported membranes was established and validated by experimental data. The model has the ability to predict the sintering behavior of the CSG-TiO2, in terms of the reduction of specific surface area versus the time of heating, particularly at the initial and intermediate stages of the sintering.

Keshmiri, Mehrdad

216

Nitric oxide-releasing sol-gels as antibacterial coatings for orthopedic implants.  

PubMed

To assess the benefits of nitric oxide (NO)-releasing sol-gels as potential antibacterial coatings for orthopedic devices, medical-grade stainless steel is coated with a sol-gel film of 40% N-aminohexyl-N-aminopropyltrimethoxysilane and 60% isobutyltrimethoxysilane. Upon converting the diamine groups in these films to diazeniumdiolate NO donors, the NO release from the sol-gel-coated stainless steel is evaluated at both ambient and physiological temperature. Sol-gel films incubated at 25 degrees C have a lower NO flux over the first 24 h compared to those at 37 degrees C, but release more than five times longer. The bacterial adhesion resistance of NO-releasing coatings is evaluated in vitro by exposing bare steel, sol-gel, and NO-releasing sol-gel-coated steel to cell suspensions of Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis at 25 degrees C and 37 degrees C. Cell adhesion to bare and sol-gel-coated steel is similar, while NO-releasing surfaces have significantly less bacterial adhesion for all species and temperatures investigated. PMID:15353203

Nablo, Brian J; Rothrock, Aaron R; Schoenfisch, Mark H

2005-03-01

217

The controlled release of drugs from emulsified, sol gel processed silica microspheres.  

PubMed

Controlled release silica sol gels are room temperature processed, porous, resorbable materials with generally good compatibility. Many molecules including drugs, proteins and growth factors can be released from sol gels and the quantity and duration of the release can vary widely. Processing parameters render these release properties exquisitely versatile. The synthesis of controlled release sol gels typically includes acid catalyzed hydrolysis to form a sol with the molecules included. This is then followed by casting, aging and drying. Additional steps such as grinding and sieving are required to produce sol gel granules of a desirable size. In this study, we focus on the synthesis of sol gel microspheres by using a novel process with only two steps. The novelty is related to acid-base catalysis of the sol prior to emulsification. Sol gel microspheres containing either vancomycin (antibiotic) or bupivacaine (analgesic) were successfully synthesized using this method. Both drugs showed controlled, load dependent and time dependent release from the microspheres. The in vitro release properties of sol gel microspheres were remarkably different from those of sol gel granules produced by grinding and sieving. In contrast to a fast, short-term release from granules, the release from microspheres was slower and of longer duration. In addition, the degradation rate of microspheres was significantly slower than that of the granules. Using various mathematical models, the data reveal that the release from sol gel powder is governed by two distinct phases of release. In addition, the release from emulsified microspheres is delayed, a finding that can be attributed to differences in surface properties of the particles produced by emulsification and those produced by casting and grinding. The presented results represent an excellent data set for designing and implementing preclinical studies. PMID:19010531

Radin, Shula; Chen, Tiffany; Ducheyne, Paul

2008-11-17

218

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

SciTech Connect

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)

NONE

1995-12-01

219

The effect of Na 2CO 3, NaF and NH 4OH on the stability and release behavior of sol–gel derived silica xerogels embedded with bioactive compounds  

Microsoft Academic Search

Stability, defined as the reproducible behavior of a device upon its storage, is an important issue in pharmaceutical formulation. Silica xerogels obtained through the sol–gel route are relatively new as matrices for the controlled release of drugs. In some cases, it was observed that their behavior changes upon storage, so that they cannot always be defined as “stable”. This occurs

M. Morpurgo; D. Teoli; M. Pignatto; M. Attrezzi; F. Spadaro; N. Realdon

2010-01-01

220

Elaboration by the sol-gel process of fluorescent sensitive coatings for gas chemical sensors  

NASA Astrophysics Data System (ADS)

Fluorescent chemical sensors have been widely exploited for the detection and quantification of trace explosives. Their performances are mainly dependent on the sensitive material. Fluorescent organic materials are very efficient in terms of sensitivity, selectivity and response time but their degradation is a major drawback. Sol-gel materials offer a much longer life span, especially in the case of inorganic sensitive coatings. The elaboration of sol-gel sensitive films is detailed in this paper. Two examples of sol-gel fluorescent sensitive materials are presented: a hybrid organic-inorganic film and an inorganic material.

Oudot, N.; Le Guevel, X.; Ambard, C.; Pereira, F.; Belleville, P.; Hairault, L.; Vallé, K.; Autissier, D.; Sanchez, C.

2012-05-01

221

The growth and characterization of L-arginine phosphate microcrystals in a silica sol gel matrix  

NASA Astrophysics Data System (ADS)

Silica sol-gel has proven to be a versatile material that can host a number of inorganic and organic dopant molecules, providing an environment in which they may retain their activity. This dissertation studies the relationship between crystallization and gelation in a system consisting of L-arginine phosphate (LAP), an organic non-linear optical crystal, in an inorganic silica sol-gel matrix. The objectives of this research are to investigate the mechanisms of crystal nucleation and growth in a silica sol-gel matrix. Complex impedance measurements were used to determine the solubility of LAP in sol-gel as a function of temperature, the induction times for crystallization of LAP, and the overall rate of LAP precipitation. Analysis of the induction times was performed to determine the interfacial energies, surface entropy factors, and nucleation and growth mechanisms of LAP in sol-gel over a range of temperatures and concentrations. Nucleation and growth of LAP in sol-gel was found to follow a model of primary nucleation followed by spiral growth (5°C to 20°C) or normal growth (25°C to 40°C) for LAP concentrations high enough that nucleation occurs in the sol. For lower LAP concentrations, heterogeneous nucleation occurs on sample interfaces or electrodes. The solubility of LAP in silica sol-gel was found to follow an Arrhenius relationship, with an enthalpy of solution of 0.68 eV. The enthalpy of solution for LAP in sol-gel is comparable to that in aqueous solutions, while the pre-exponential factor is about 8 times smaller in sol-gel than in water. The interfacial energies of LAP in sol-gel are close to, but slightly larger than, those in aqueous solution. The interfacial energies decrease with increasing temperature at about the same rate in sol-gel as in aqueous solution. Conductivity of LAP in sol-gel is primarily through proton conduction and follows an Arrhenius relationship with an activation energy for conduction of 0.26 eV and a pre-exponential factor that depends upon the square root of the LAP concentration.

Faltens, Tanya Anne

222

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

SciTech Connect

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.

Loy, D.A.; Rahimian, K.

1999-04-05

223

Solventless sol-gel chemistry through ring-opening polymerization of bridged disilaoxacyclopentanes  

SciTech Connect

Ring-opening polymerization (ROP) of disilaoxacyclopentanes has proven to be an excellent approach to sol-gel type hybrid organic-inorganic materials. These materials have shown promise as precursors for encapsulation and microelectronics applications. The polymers are highly crosslinked and are structurally similar to traditional sol-gels, but unlike typical sol-gels they are prepared by an organic base or Bronsted acid (formic or triflic acid), without the use of solvents and water, they have low VOC's and show little shrinkage during processing.

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.

2000-05-01

224

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

NASA Astrophysics Data System (ADS)

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.

Gan, Lu

225

Synthesis of lead-free (K, Na)(Nb, Ta)O3 nanopowders using a sol-gel process.  

PubMed

Lead-free (K0.5Na0.5)(Nb0.7Ta0.3)O3 piezoelectric material was successfully synthesized via a sol-gel process. Crystalline (K0.5Na0.5)(Nb0.7Ta0.3)O3 nanopowders were obtained after heat treatment at 700 degrees C. The particle size was estimated to be 87nm +/- 23 nm. The transmission electron microscopy images showed that individual nanoparticles were single crystalline and had a pseudo-cubic structure with a lattice parameter of -3.96 angstroms. Both X-ray diffraction and scanning electron microscopy studies consistently showed that the crystallization of the (K0.5Na0.5)(Nb0.7Ta0.3)O3 occurred slightly above 500 degrees C. The samples have an appropriate stoichiometry as found via energy dispersive X-ray spectroscopy. The demonstration of the synthesis of (K0.5Na0.5)(Nb0.7Ta0.3)O3 via a sol-gel process as presented in this paper can provide an important foundation for the development of a synthetic route towards (K0.5Na0.5)(Nb0.7Ta0.3)O3 doped with various other elements for high performance piezoelectric devices. PMID:22849167

Rajesh, Dodla; Kim, Seungwook; Jeong, Jinhoo; Nahm, Sahn; Kim, Woong

2012-04-01

226

Structural and Dynamical Properties of the Sol-Gel Transition. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

A variety of experimental techniques (multinuclear NMR, Raman, fluorescence polarization, small-angle neutron scattering, viscosity, turbidity. static and dynamic light scattering experiments) have been employed to investigate the nature of the Sol-gel tr...

R. Winter D. W. Hua X. Song W. Mantuin J. Jonas

1990-01-01

227

Sol-Gel Synthesis and Densification of Aluminoborosilicate Powders. Part 1: Synthesis.  

National Technical Information Service (NTIS)

Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowin...

J. Bull G. Selvaduray D. Leiser

1992-01-01

228

Immobilization of Pseudomonas cepacia lipase in a phyllosilicate sol-gel matrix: effectiveness as a biocatalyst.  

PubMed

A novel procedure is described for immobilizing a lipase from Pseudomonas cepacia (PS-30) within a phyllosilicate sol-gel matrix. The method is based on cross-linking a phyllosilicate clay with silicate polymers produced by the controlled hydrolysis of tetramethyl orthosilicate (TMOS). The activity of the phyllosilicate sol-gel-immobilized lipase was dependent upon the type of alkylammonium salt, inorganic catalyst and volume ratio of phyllosilicate clay to TMOS used. Lipase PS-30 immobilized in this way was more stable and had higher activity compared with the free lipase. Studies on the lipase-catalysed esterification of lauric acid with octan-1-ol in iso-octane showed that under controlled water activity conditions the phyllosilicate sol-gel-immobilized lipase had better activity compared with other supported lipase preparations. In addition, the phyllosilicate sol-gel-immobilized lipase was reusable for at least five esterification cycles without significant loss of activity. PMID:10814587

Hsu, A F; Foglia, T A; Shen, S

2000-06-01

229

Novel Sol-Gel Composite Second Harmonic Generator and Electrooptic Modulator.  

National Technical Information Service (NTIS)

The development of organic inorganic second order nonlinear optical materials is discussed in light of the need to obtain practical (high performance, stable operation, processable and low cost) alternatives to inorganic crystals. Sol gel materials have w...

R. Burzynski M. Casstevens S. Ghosal

1995-01-01

230

Dielectric properties of silicon dioxide and silicon-oxynitride sol/gel thin films  

SciTech Connect

Sol-gel film coatings are considered as candidate abrasion resistant and anti-reflection coatings for photovoltaic concentrator solar cells. The studies described in this report concern the electrical breakdown potential as a function of processing in ammonia. It has previously been determined that large (5-40 atomic percent) amounts of nitrogen can be incorporated into silica sol-gels by ammonia exposure during the densification process to form an oxynitride. Most of the expected behavior of the nitrided sol/gel deposits were masked due to the presence of alkali impurities and interfacial defects. The dielectric strength of such films was no greater than silicon oxide films thermally grown. The distribution of breakdown potential was much narrower, however, for nitrided films. For the expected improved properties of nitrided sol gel films to be seen, more care with the purity of the deposition materials and atmosphere will need to be exercised.

Carman, L.A.; Pantano, C.G.

1986-03-01

231

Physical and Chemical Properties of Sol-Gel Processing.  

NASA Astrophysics Data System (ADS)

Sol-gel processing is known as a novel technique to synthesize glasses using liquid chemicals. Hydrolysis reaction can basically determine a polymeric structure resulting in glasses of different properties. The hydrolysis reaction of tetramethyl orthosilicate, TMOS, is investigated at pHs of 4.9, 6.0, 7.5 of water, and with the chemical additives: formamide, acetone, methanol acetonitrile, and dioxane. The chemical additives are used for a solvation effect, and the water of different pHs is used as a catalyst. The experiment has been completed as a function of time, and at pressures from 1 to 2 kilobars. The rate constant is determined using Raman spectroscopy. The roles of viscosity, pressure induced mobility, concentration of hydronium and hydroxyl ions, volumes of activations, dipole moment, dielectric constant, and hydrogen bonds are discussed. After hydrolysis and polymerization, gelation occurs. The Positronium Decay Technique is also used to measure pore sizes of the silica gels. The results are compared with the BET method. The gels of pores larger than 50 A are used to synthesize titanium and boron doped gels and to characterize their physical properties. Infrared spectroscopy is used to identify Si-O-Ti and Si-O-B bonds.

Hoang, Geun Chang

232

Cobalt silicon mixed oxide nanocomposites by modified sol gel method  

NASA Astrophysics Data System (ADS)

Cobalt silicon mixed oxide materials (Co/Si=0.111, 0.250 and 0.428) were synthesised starting from Co(NO3)2·6H2O and Si(OC2H5)4 using a modified sol gel method. Structural, textural and surface chemical properties were investigated by thermogravimetric/differential thermal analyses (TG/DTA), XRD, UV vis, FT-IR spectroscopy and N2 adsorption at -196 °C. The nature of cobalt species and their interactions with the siloxane matrix were strongly depending on both the cobalt loading and the heat treatment. All dried gels were amorphous and contained Co2+ ions forming both tetrahedral and octahedral complexes with the siloxane matrix. After treatment at 400 °C, the sample with lowest Co content appeared amorphous and contained only Co2+ tetrahedral complexes, while at higher cobalt loading Co3O4 was present as the only crystalline phase, besides Co2+ ions strongly interacting with siloxane matrix. At 850 °C, in all samples crystalline Co2SiO4 was formed and was the only crystallising phase for the nanocomposite with the lowest cobalt content. All materials retained high surface areas also after treatments at 600 °C and exhibited surface Lewis acidity, due to cationic sites. The presence of cobalt affected the textural properties of the siloxane matrix decreasing microporosity and increasing mesoporosity.

Esposito, Serena; Turco, Maria; Ramis, Gianguido; Bagnasco, Giovanni; Pernice, Pasquale; Pagliuca, Concetta; Bevilacqua, Maria; Aronne, Antonio

2007-12-01

233

Sol-gel template synthesis of semiconductor nanostructures  

SciTech Connect

The template method for preparing nanostructures entails synthesis of the desired material within the pores of a nanoporous membrane or other solid. A nonofibril or tubule of the desired material is obtained within each pore. Methods used previously to deposit materials within the pores of such membranes include electrochemical and electroless deposition and in situ polymerization. This paper describes the first use of sol-gel chemistry to prepare semiconductor nanofibrils and tubules within the pores of an alumina template membrane. TiO{sub 2}, WO{sub 3}, and ZnO nanostructures have been prepared. TiO{sub 2} nanofibrils with diameters of 22 nm were found to be single crystals of anatase with the c-axis oriented along the fibril axis. Bundles of these fibrils were also found to be single crystalline, suggesting that the individual fibrils are arranged in a highly organized fashion within the bundle. Finally, 200 nm diameter TiO{sub 2} fibrils were used as photocatalysts for the decomposition of salicylic acid. 30 refs., 8 figs.

Lakshmi, B.B.; Dorhout, P.K.; Martin, C.R. [Colorado State Univ., Fort Collins, CO (United States)

1997-03-01

234

Tuning of sol-gel derived PZT MEMS resonators  

NASA Astrophysics Data System (ADS)

This paper demonstrates the tunability of resonant frequencies for MEMS piezoelectric resonators acting in the d33 mode by experiment and theoretical analysis. Thin-film MEMS beams made by sol-gel PZT processing are first fabricated and tested to investigate the tuning capability. The three-layered interdigitated-electrode trapezoidal beams are then modeled by finite element analysis for validation. Beam curl and undercutting are also examined to present an alternative way of finding the stress gradient in comparison to Stoney's formula. The experimental and analytical results indicate that piezoelectric MEMS resonators have the ability to passively tune their resonant frequencies between open-circuit and short-circuit frequencies. Tuning of 0.2-0.6% is demonstrated experimentally, which compares with finite element predictions of 1.02-1.08%. Consideration is given to the reason for the differences in experimental percentages versus those predicted numerically, including the use of bulk PZT values in the ANSYS simulations, the undercut and curling effects of fabrication, and the low percentage of piezoelectric poling in the length direction.

Knight, Ryan R.; Frederick, Amanda A.; Mo, Changki; Clark, William W.

2010-12-01

235

Synthesis of High Purity Cordierite via Sol-Gel Method  

NASA Astrophysics Data System (ADS)

Cordierite (2MgO2.2Al2O3.5SiO2) had many excellent properties such as low thermal expansion, good thermal shock resistance, sufficient mechanical strength, high refractoriness and others. Therefore, it had been widely used in many fields such as packaging materials for substrate in electronic packaging, special refractory and containers for high temperature application, potential sealing materials for high temperature devices such as high intensity discharge lamps and others. In this study, high purity Cordierite was successfully synthesized via sol-gel method using TEOS, Al(NO3)3.9H2O, Mg(NO3)2.6H2O as starting materials and sintered at 1300° C. Powders obtained were characterized using XRD, FTIR and CTE analysis. XRD result showed that high purity of ?-cordierite was obtained with Spinel phase as a minor impurity. FTIR spectroscopy result showed the band characteristics for ?-cordierite which supported the XRD result. The CTE value for synthetic ?-cordierite is 2×10-6 which proved that high purity ?-cordierite was obtained.

Hasmaliza, M.; Srimala, S.; Choo, Y. P.

2010-03-01

236

High temperature sol–gel insulation coatings for HTS magnets and their adhesion properties  

Microsoft Academic Search

This paper describes the adhesion properties of sol–gel insulation coatings with silver tape substrates using a mini-tensile-testing for HTS magnets. The sol–gel coatings were produced using solutions of Zr, Mg, Y, Ce, In and Sn based organometallic compounds. The growth mechanism of these coatings on Ag and AgMg sheathed Bi-2212 superconducting tapes was characterized by scanning electron microscopy, energy dispersive

E. Celik; E. Avci; Y. S. Hascicek

2000-01-01

237

Tribological behavior of sol–gel TiO 2 films on glass  

Microsoft Academic Search

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

Wenguang Zhang; Weimin Liu; Chengtao Wang

2002-01-01

238

Investigation of Sol-Gel Derived Zr0 2 Thin Films by Nanoindentation  

Microsoft Academic Search

The near surface mechanical response of multi-layer sol-gel derived ZrO2 thin films has been investigated by nanoindentation. Five layer sol-gel coatings deposited on AISI 304 stainless steel were prepared by dip coating and subsequently heat treated at temperatures ranging from 400-700 °C. Elastic modulus and hardness were measured at depths corresponding to 7-10 percent of the film thickness. Heat treatment

D. A. Lucca; M. J. Klopfstein; R. Ghisleni; A. Gude; A. Mehner; W. Datchary

2004-01-01

239

Bioencapsulation within synthetic polymers (Part 1): sol–gel encapsulated biologicals  

Microsoft Academic Search

Since its inception a decade ago, sol–gel encapsulation has opened up an intriguing new way to immobilize biological materials. An array of substances, including catalytic antibodies, DNA, RNA, antigens, live bacterial, fungal, plant and animal cells, and whole protozoa, have been encapsulated in silica, metal-oxide, organosiloxane and hybrid sol–gel polymers. The advantages of these ‘living ceramics’ might give them applications

Iqbal Gill; Antonio Ballesteros

2000-01-01

240

Sol-Gel Formation of Reticular Methyl-Silicate Materials by Hydrogen Peroxide Decomposition  

Microsoft Academic Search

A new method for the formation of reticular silicate and organically modified silicate is introduced. Monoliths were prepared by incorporating a few percent hydrogen peroxide in the sol-gel starting solution. For example, incorporation of 6–10% (v) hydrogen peroxide in base catalyzed sol-gel precursors of methyl-Ormosil yielded macroporous monoliths with a bi-modal pore size distribution. The average characteristic pore diameters were

J. Gun; O. Lev; O. Regev; S. Pevzner; A. Kucernak

1998-01-01

241

Characterization of zirconia-based catalysts prepared by precipitation, calcination, and modified sol-gel methods  

Microsoft Academic Search

Zirconia-based catalysts were synthesized by various methods and were evaluated for the synthesis of isobutane and isobutene from CO hydrogenation. The methods of preparation included precipitation (ZrO[sub 2] (PPT)), calcination of zirconyl salt (ZrO[sub 2] (H-0304)), and a modified sol-gel method (ZrO[sub 2] (sol-gel)). Acid-base properties of zirconia were affected by the method of preparation. The number of acidic sites

Zhentao Feng; Walter S. Postula; Aydin Akgerman; Rayford G. Anthony

1995-01-01

242

Mixed Pyridine-phenol Boron Complex Encapsulated in Polymer\\/Silica Hybrid Sol-gel Matrix  

Microsoft Academic Search

A novel pyridine-phenol boron complex[(dppy)BF] was encapsulated into polymer\\/silica composite matrix by sol-gel process. UV-Vis absorption spectra show that this process can control the aggregation structure of complex (dppy)BF. The results of photoluminescence of (dppy)BF in sol-gel composite film indicate that both fluorescence intensity and photostability are markedly increased using this method compared with other methods, which increases the practical

Wei DONG; Jun TANG; Yue WANG

2008-01-01

243

Antimicrobial coatings on textiles–modification of sol–gel layers with organic and inorganic biocides  

Microsoft Academic Search

Antimicrobial textile materials were produced by sol–gel coatings with embedded biocidal compounds. For preparation a sol–gel\\u000a procedure was used, starting from pure silica sols and 3-glycidyloxypropyltriethoxysilane (GLYEO) containing silica sols.\\u000a These sols were modified with silver compounds, hexadecyltrimethyl-ammonium-p-toluolsulfonat (HTAT) and copper compounds, respectively. The investigations were performed on viscose fabrics as function\\u000a of the concentration of biocidal compounds and of

Boris Mahltig; Dirk Fiedler; Anja Fischer; Paul Simon

2010-01-01

244

Conformal sol-gel coatings on three-dimensional nanostructured templates  

Microsoft Academic Search

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

Michael R. Weatherspoon

2008-01-01

245

Fabrication of superhydrophobic sol–gel composite films using hydrophobically modified colloidal zinc hydroxide  

Microsoft Academic Search

A superhydrophobic sol–gel composite film was fabricated by incorporating hydrophobically modified colloidal zinc hydroxide (CZH) in sol–gel matrix. CZH was prepared by controlled precipitation and modified by treatment with stearic acid. The concentration of stearic acid and stirring time were optimized to obtain modified CZH with very high water contact angle (WCA) of 165° and sliding angle (SA)<2°. X-ray diffraction

R. V. Lakshmi; Bharathibai J. Basu

2009-01-01

246

Hybrid silica sol–gel coatings on Austempered Ductile Iron (ADI)  

Microsoft Academic Search

Sol–gel organic–inorganic hybrid coatings are being increasingly used to protect metal surfaces. The presence of non-hydrolysable groups in their structure can lead to the formation of coatings with properties intermediate between glasses and organic polymers. Crack-free, homogeneous and adherent hybrid silica sol–gel coatings around 1 ?m thick were obtained by dip-coating on glass and Austempered Ductile Iron (ADI). Homogeneous multilayer

Andrés Pepe; Pablo Galliano; Silvia Ceré; M. Aparicio; A. Durán

2005-01-01

247

Fabrication of ridge waveguides by UV embossing and stamping of sol-gel hybrid materials  

Microsoft Academic Search

Multimode large core (45×35 ?m2) optical ridge waveguides are fabricated in the room temperature by ultraviolet (UV) imprinting of soft rubber template with the organic-inorganic sol-gel hybrid materials. The fabrication processes may be either well-known UV embossing or stamping. A new sol-gel hybrid material that is thermally stable has been developed for the fabrication of low-loss optical waveguides. The UV

Woo-Soo Kim; Jong-Hwan Lee; Sang-Yung Shin; Byeong-Soo Bae; Young-Cheol Kim

2004-01-01

248

Structural Evolution During Reaction to Form Aluminum Titanate from Sol-Gel Precursors  

Microsoft Academic Search

Aluminum titanate ceramic materials have been obtained by field-activated sintering of amorphous sol-gel powder precursors. Aluminum titanate formation started at 1000°C. The structural evolution with temperature from the amorphous sol-gel state to the final fully densified ceramic product has been monitored by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and electron microscopy. The full crystallization of aluminum titanate occurred at 1200°C.

Lia A. Stanciu; Joanna R. Groza; A. Jitianu; Maria Zaharescu

2004-01-01

249

Encapsulation of proteins in bulk and thin film sol-gel matrices  

Microsoft Academic Search

This paper considers the nature of the interactions between the sol-gel derived inorganic matrix and a specific biomolecule,\\u000a cytochrome c. Optical absorption and impedance spectroscopies are used to characterize the influence of synthesis conditions\\u000a on the protein’s stability and conformation within the silica matrix. In some instances, encapsulation within the sol-gel\\u000a matrix provides stabilization. For example, protein denaturation is reversible

B. C. Dave; J. M. Miller; B. Dunn; J. S. Valentine; J. I. Zink

1997-01-01

250

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

Microsoft Academic Search

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

Alexander J. Fielding; Christopher C. Davis

1998-01-01

251

Microalgae fiber optic biosensors for herbicide monitoring using sol–gel technology  

Microsoft Academic Search

Three microalgal species (Dictyosphaerium chlorelloides (D.c.), Scenedesmus intermedius (S.i.) and Scenedesmus sp. (S.s.)) were encapsulated in silicate sol–gel matrices and the increase in the amount of chlorophyll fluorescence signal was used to quantify simazine. Influence of several parameters on the preparation of the sensing layers has been evaluated: effect of pH on sol–gel gelation time; effect of algae density on

Elena Peña-Vázquez; Emilia Maneiro; Concepción Pérez-Conde; Maria Cruz Moreno-Bondi; Eduardo Costas

2009-01-01

252

Preparation and optical properties of sol gel deposited electrochromic iron oxide films  

Microsoft Academic Search

The preparation and optical properties of sol-gel deposited iron oxide films are investigated in this study. The films are deposited on glass by spin-coating from polymeric sol-gel solutions. The coating solutions were prepared from Fe(OCH3H7)3 and isopropanol. Fe2O3 films were obtained at a firing temperature 180 degrees Celsius. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM),

Nilgun Ozer; Fatma Tepehan; Galip Tepehan

1997-01-01

253

Platinum nanoparticles-doped sol–gel\\/carbon nanotubes composite electrochemical sensors and biosensors  

Microsoft Academic Search

Platinum nanoparticle-doped sol–gel solution is prepared and used as a binder for multi-walled carbon nanotubes (CNT) for the fabrication of electrochemical sensors. Amine group containing sol–gel solution is selected to utilize the affinity of –NH2 groups toward metal nanoparticles for stabilization the nanoparticles in solution. The resulting CNT-silicate material brings new capabilities for electrochemical devices by using the synergistic action

Minghui Yang; Yunhui Yang; Yanli Liu; Guoli Shen; Ruqin Yu

2006-01-01

254

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

Microsoft Academic Search

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

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

2009-01-01

255

Sol-Gel Synthesis and Characterization of Copper Stabilized Zirconia Nanoparticles  

Microsoft Academic Search

A sol-gel method is investigated to synthesize CuO-ZrO2 nanoparticles as catalyst for hydrogen production from methanol. Finer precursor nanoparticles give rise to larger specific areas in catalyst which result in a high hydrogen production. The effects of some critical process parameters on the sol-gel synthesis of CuO-ZrO2 nanoparticles are studied. These parameters are affected on synthesis of CuO-ZrO2 when it

Y. Vahidshad; H. Abdizadeh; H. R. Baharvandi; M. Akbari Baseri

2011-01-01

256

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

Microsoft Academic Search

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

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

2000-01-01

257

Non-Aqueous Primary Cell.  

National Technical Information Service (NTIS)

This patent application relates to electrochemical cells and especially to high-energy, liquid cathode, non-aqueous lithium electrochemical cells free from highly toxic materials. A non-aqueous lithium electrochemical cell is described which includes a ha...

S. D. James P. H. Smith K. M. O'Neill M. H. Wilson

1986-01-01

258

Biocompatibility evaluation of sol-gel coatings for subcutaneously implantable glucose sensors.  

PubMed

The objective of the current investigation is to determine the soft-tissue biocompatibility of sol-gel matrices which can be used to optimize the properties of implantable glucose sensors. The biocompatibility of sol-gel matrices with heparin, dextran sulphate, Nafion, polyethylene glycol, and polystyrene sulphonate was examined in vitro in simulated body fluid and with cell culture experiments using human dermal fibroblasts. Finally, an in vivo study was performed. Therefore, sol-gel coated polystyrene discs were inserted subcutaneously in the back of rabbits. After 4 and 12 weeks, the implants with surrounding tissue were retrieved and processed histologically. In simulated body fluid, the formation of a granular calcium phosphate precipitate was observed. Cell proliferation on polyethylene glycol, Nafion, and heparin coated substrates was comparable to control samples and significantly higher than on dextran sulphate and polystyrene sulphate coated substrates. Light microscopic evaluation of the retrieved in vivo samples showed a fair tissue reaction to all materials. Histomorphometric analysis demonstrated that there were no differences in tissue response to the different sol-gel coatings. In conclusion, sol-gel matrices exhibit a fair biocompatibility both in vitro and in vivo. These results will form the basis for further research into the real merits of sol-gel coatings in optimizing the properties of subcutaneously implantable glucose sensors. PMID:10619680

Gerritsen, M; Kros, A; Sprakel, V; Lutterman, J A; Nolte, R J; Jansen, J A

2000-01-01

259

Sol-gel processes and materials. January 1970-August 1988 (Citations from the US Patent data base). Report for January 1970-August 1988  

SciTech Connect

This 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, cataylsts and catalyst supports, nuclear fuels preparation, abrasives for grinding wheels, Sol-Gel production of microspheres, Sol-Gel thin films and coatings, photographic materials, and dental materials. (Contains 71 citations fully indexed and including a title list.)

Not Available

1988-08-01

260

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

NASA Astrophysics Data System (ADS)

The Centre d'Etudes de Limeil-Valenton is currently involved in a project which consists of the construction of a 2 MJ/500TW pulsed Nd:glass laser devoted to inertial confinement fusion research. With 240 laser beams, the proposed megajoule-class laser conceptual design necessitates 44-cm X 44-cm X 6-cm cavity-end mirrors representing more than 50-m2 of coated area. These dielectric mirrors are made of quarterwave stacks of SiO2 and ZrO2-PVP and are prepared from colloidal suspensions using the sol-gel route. After a sustained search effort, we have prepared (SiO2/ZrO2- PVP)10 mirrored coatings with up to 99 percent reflection at 1053-nm and for different incidence use. Adequate laser-conditioned damage thresholds ranging 14-15 J/cm2 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.

Belleville, Philippe F.; Pegon, Philippe M.

1997-05-01

261

Optical constants and electrochromic properties of sol-gel V{2}O{5} thin films  

NASA Astrophysics Data System (ADS)

Vanadium pentoxide thin films are prepared by the sol-gel route by dissolving V{2}O{5} powder (99.5% purity) in H{2}O{2} solution. The solution is spin - coated on glass substrates for optical (UV-VIS-NIR) analysis, and on ITO-coated glass substrates for electrochromic measurements. The samples are then annealed at 150 ° C for 1 hour. The resulting films have a yellow-orange color, typical of polycrystalline V{2}O{5}. The optical and physical constants (n, ? , Eg, the thickness d and the mean thickness inhomogeneity ? ) of the films are calculated using a simple and accurate method based on the transmission spectrum alone. Electrochromism of the films is studied using cyclic voltammetry (CV) in propylene carbonate solution containing 1 mol/1LiClO{4}. The films show reversible multichromism (yellow-green-blue) upon Li+ ion insertion/extraction. The absorbance of films colored at three different potentials is measured in the UV-VIS wavelength range, and this study shows that the changes in the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of the sputtered films already studied in our previous works.

Benmoussa, M.; Outzourhit, A.; Bennouna, A.; Ameziane, E. L.

2005-03-01

262

Growth of epitaxial LaAlO{sub 3} and CeO{sub 2} films using sol-gel precursors  

SciTech Connect

LaAlO{sub 3} and CeO{sub 2} films have been successfully grown using sol-gel precursors. LaAlO{sub 3} precursor solution has been prepared from a metal alkoxide route and spun-cast on a SrTiO{sub 3} (100) single crystal to yield an epitaxial film following pyrolysis at 800{degrees}C in a rapid thermal annealer. A CeO{sub 2} precursor solution has been made using both an aqueous and an alkoxide route.

Shoup, S.S.; Paranthaman, M.; Beach, D.B. [and others

1996-04-01

263

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

PubMed

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

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

2012-10-24

264

Synthesis of geranyl acetate by esterification with lipase entrapped in hybrid sol-gel formed within nonwoven fabric  

Microsoft Academic Search

Candida cylindracea lipase was entrapped in organic-inorganic hybrid sol-gel polymers made from tetramethoxysilane (TMOS) and alkyltrimethoxysilanes.\\u000a By forming the gels within the pores of a nonwoven polyester fabric, a novel immobilized biocatalyst in sheet configuration\\u000a based on sol-gel en-trapment of the enzyme was obtained. Lipases immobilized in sol-gel matrices efficiently catalyzed the\\u000a direct esterification reaction of geraniol and acetic acid

Jyh-Ping Chen; Wei-Shin Lin; Min-Far Chang

2002-01-01

265

Investigation of a new electrochemical cyanide sensor based on Ag nanoparticles embedded in a three-dimensional sol–gel  

Microsoft Academic Search

In this study, a novel sensor for cyanide detection was developed by self-assembling of a sol–gel network and silver nanoparticles. Silver doped silica nanocomposite was synthesized via a sol–gel technique combined with a nanoparticle preparing method. Then a cleaned gold electrode (GE) was immersed in a hydrolyzed mercaptopropyltrimethoxysilane (MPS) sol–gel solution containing Ag nanoparticles (AgNPs) to assemble three-dimensional silica gel.

Aboozar Taheri; Meissam Noroozifar; Mozhgan Khorasani-Motlagh

2009-01-01

266

Synthesis of nanocrystalline NiCuZn ferrite powders by sol-gel auto-combustion method  

NASA Astrophysics Data System (ADS)

A nitrate-citrate gel was prepared from metal nitrates and citric acid by sol-gel process, in order to synthesize Ni0.25Cu0.25Zn0.50Fe2O4 ferrite. The thermal decomposition process was investigated by DTA-TG, IR and XRD techniques. The results revealed that the nitrate-citrate gel exhibits self-propagating combustion behavior. After combustion, the gel directly transformed into single-phase, nano-sized NiCuZn ferrite particles with spinel crystal structure. The synthesized powder can be densified at a temperature lower than 900 degC. The sintered body possesses fine-grained microstructure, good frequency stability and high-quality factor compared to the sample prepared by conventional ceramic route.

Yue, Z.; Zhou, J.; Li, L.; Zhang, H.; Gui, Z.

2000-01-01

267

Sol-gel preparation and characterization of nanoporous ZnO/SiO 2 coatings with broadband antireflection properties  

NASA Astrophysics Data System (ADS)

Nanoporous ZnO/SiO 2 bilayer coatings were prepared on the surface of glass substrates via sol-gel dip-coating process. The structural, morphological and optical properties of the coatings were characterized. The refractive indices of ZnO layer and SiO 2 layer are 1.34 and 1.21 at 550 nm, respectively. The transmittance and reflectance spectra of the coatings were investigated and the broadband antireflection performance of the bilayer structure was determined over the solar spectrum. The solar transmittances in the range of 300-1200 nm and 1200-2500 nm are increased by 6.5% and 6.2%, respectively. The improvement of transmittance is attributed to the destructive interference of light reflected from interfaces between the different refractive-index layers with an optimized thickness. Such antireflection coatings of ZnO/SiO 2 provide a promising route for solar energy applications.

Li, Dezeng; Huang, Fuqiang; Ding, Shangjun

2011-09-01

268

Structural and optical characterization of ZrO2:CeO2 slab waveguides obtained via sol-gel  

NASA Astrophysics Data System (ADS)

Planar multilayer ZrO2:CeO2 slab waveguides were prepared by a sol-gel route and dip-coating technique onto commercial glass substrates. The coatings were microstructurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and by optical confocal microscopy. Coating thicknesses of ca. 500 nm and refractive index values of 2.069 ± 0.001 and 2.087 ± 0.001, respectively for TE and TM light polarization modes, were calculated by Dark m-line spectroscopy. This is consistent with the birefringent character of the coating, associated to the presence of anisotropic crystalline phases within the coating's vitreous matrix. Finally, propagation losses of 0.9 ± 0.2 and 1.5 ± 0.2 dB/cm were determined by the scattered light measurement for TE and TM polarization modes, respectively.

Rey-García, F.; Flores-Arias, M. T.; Gómez-Reino, C.; De La Fuente, G. F.; Assenmacher, W.; Mader, W.; Berneschi, S.; Pelli, S.; Nunzi-Conti, G.; Righini, G. C.

2012-12-01

269

Investigation of corrosion protection performance of sol-gel surface treatments on AA2024-T3  

NASA Astrophysics Data System (ADS)

The dissertation research project addresses the technologically important problem of replacement of chromate based coatings for corrosion protection of aircraft. A review of corrosion processes in high-strength aluminum alloys indicated that the strengthening intermetallic precipitates provide local cathodic areas, which may initiate surface pitting. The mechanisms of chromate inhibition in these localized corrosion processes were identified. The environmental hazard of chromates was also highlighted, serves as the impetus for chromate coating replacement. Sol-gel coatings are shown as an excellent alternative, based on environment compliance, flexibility in the composition control, and reasonable costs. Several sol-gel coatings were formulated and applied to the surface of an AA2024-T3 alloy. The coating composition and bonding were analyzed with XPS and FTIR, surface morphology was studied with SEM and AFM, and corrosion protection properties were tested with EIS, PDS, salt water immersion, and salt-fog exposure. The results demonstrated that epoxy-zirconate sol-gel coatings can provide excellent barrier properties. A novel SVET technique was applied for studies of local electrochemical processes in the pitting formation. This technique was further refined in model studies of aluminum surfaces with artificially created local cathodic regions, experimental studies of chromate inhibition with pit formation, and pitting development studies in sol-gel coatings with artificially introduced defects. Mechanisms of pitting development and inhibition with the pit initiation and growth kinetics were established. The Zr-epoxy coatings are subjected to the pit development and undercutting in the absence of the corrosion inhibitors. Several organic and non-organic inhibitors were evaluated in the sol-gel coating composition. Organic inhibitors had a better compliance with sol-gel chemistry and were identified for future studies. Experiments were performed to verify that sol-gel coatings can be used as barrier layers in complex coating systems. The results clearly demonstrated that Zr-epoxy sol-gel coatings are a viable replacement for the currently used chromate-based surface treatments. This work expands the fundamental knowledge of chromate coating replacement with chromate-free sol-gel coatings and identifies possible ways to implement this goal.

Voevodin, Natalia Nikolajevna

270

Affinity of antifluorescein antibodies encapsulated within a transparent sol-gel glass  

SciTech Connect

Low temperature processed, porous sol-gel glasses represent a new class of materials for immobilization of biomolecules. The ability to form these materials into films, monoliths, and fibers to produce high-purity, porous glasses and the fact that they are optically transparent and chemically inert make them an intriguing platform for the development of chemical biosensors. In this paper, we report on the first attempt to encapsulate an intact antibody in a sol-gel glass matrix. Specifically, we present results on the affinity of sol-gel-encapsulated polyclonal antifluorescein. The results demonstrate that the sol-gel-encapsulated antibody retains an affinity for fluorescein; the affinity constant (K[sub f]) for antibody-hapten complex is on the order of 10[sup 7] M[sup [minus]1]. The encapsulation process decreases K[sub f] by about 2 orders of magnitude compared to the native system in buffer solution. The effect of aging and drying on the K[sub f] for sol-gel-encapsulated antifluorescein is reported. Finally, we demonstrate that the intact antibody affinity can be maintained using simple storage protocols. 31 refs., 8 figs.

Wang, R.; Narang, U.; Prasad, P.N.; Bright, F.V. (State Univ. of New York, Buffalo, NY (United States))

1993-10-01

271

Vibrational spectroscopic studies of (3-mercaptopropyl)trimethoxylsilane sol-gel and its coating  

NASA Astrophysics Data System (ADS)

Organosilane sol-gels have been prepared under different conditions from mercaptopropyltrimethoxysilane (MPTMS) and mercaptopropyltriethoxysilane (MPTES). These sol-gels were applied for the thin film coating on aluminum. Vibrational spectroscopy has been employed to trace and to study the proceeding of the sol-gel formation and the curing of the coated films on Al. Based on the group frequencies as well as their spectral behavior under different conditions, vibrational assignments have been made for most of the observed bands. Surface enhanced Raman scattering has revealed the chemical adsorption of MPTMS sol-gel on silver particles. Recorded reflection and absorption infrared (RAIR) spectra of coated tiles cured at different temperatures have indicated that surface reaction may occur at high temperature. The anticorrosion characters of the coated metals have been evaluated with the measured electrochemical data. Results from cyclic voltammographs have indicated that each layer of sol-gel coating would reduce the redox current across the electrode/electrolyte solution interface. Tafel plots have shown that the anodic current of the coated electrode decreases significantly and the corrosion potentials shift to the positive side.

Li, Ying-Sing; Wang, Yu; Tran, Tuan; Perkins, Anshion

2005-10-01

272

Sol-gel prepared glass for micro-optical elements and arrays  

NASA Astrophysics Data System (ADS)

Sol-gel processes of metal alkoxides involve hydrolysis of the alkoxy groups and condensation to a 3-D oxide glass network. Volume reduction of the drying gel typically results in cracking, unless sufficient relaxation is allowed to take place. Further, the common shrinkage by a factor of 2.5 and higher imposes great difficulty to obtain dimensional accuracy in thus prepared micro-optical elements. The new fast sol-gel method enables facile preparation of siloxane-based glassy materials in which polymerization is completed within minutes and curing within a few hours. The optical quality of thin films obtained by the fast sol-gel method and the ease of preparation makes this method technologically and economically attractive for micro-lenses and micro-optical arrays by replication. Micro-optical arrays are highly patterned, including sharp curvatures of small radii. This necessitates to study primarily two aspects of the sol-gel replication process: (1) the chemical constitution of the sol-gel and the reaction pathway that ensures prompt adhesion to the template during the process. (2) the surface chemical adaptation of the template that allows timing of adhesion and release of the produced elements. The adaptation of this process to the desired replication is described. Thence, the results of preliminary fabrication of micro-optical elements and arrays by this method are shown and their features discussed.

Haruvy, Yair; Gilath, Irith; Maniewictz, M.; Eisenberg, Naftali P.

1997-09-01

273

Synthesis of Indium Tin Oxide Thin Films by Cvd and Sol-Gel Processing.  

NASA Astrophysics Data System (ADS)

The object of this work was to synthesize indium tin oxide thin films on glass substrates using Chemical Vapor Deposition and Sol-gel processes. Starting materials included indium-2,2,6,6-tetramethylheptane - 3,5-dione and tin chloride as precursors for the CVD method, indium nitrates (In(NO_3)_35H _2O), tin chloride and ethylene glycol for the sol-gel method. A spin coating system was used to prepare the films by sol-gel. Analyses were carried out by X-ray powder diffraction, scanning electron microscope (SEM), four probe resistivity measurements, profilometry, atomic absorption and Hall effect measurements. Continuous, adherent films with high visible optical transmission and low resistivities were obtained at a deposition temperature of about 500 ^circC. A pressure of 1.5 torr was used for the CVD technique. Films made by a sol-gel technique were annealed under vacuum (6 times 10^{-2} torr) in order to obtain low resistivity. The films obtained by the CVD process exhibited lower resistivity and better optical transmission. Some of the differences between the films made by CVD and sol-gel have been explained in term of grain sizes. Larger grain size for the CVD films, leading to lower resistivity, were due to the growth process.

Bernard, Laurent-Sebastien

274

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

PubMed

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

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

2009-04-01

275

Sol-gel-based molecularly imprinted xerogel for capillary microextraction.  

PubMed

A novel molecularly imprinted xerogel (MIX) based on organically modified silica (ORMOSIL) was successfully prepared for on-line capillary microextraction (CME) coupled with high-performance liquid chromatography (HPLC). The sol-gel-based xerogel was prepared using only one precursor and exhibited extensive selectivity towards triazines along with significant thermal and chemical stability. Atrazine was selected as a model template molecule and 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) as a precursor in which the propylmethacrylate moiety was responsible for van der Waals, dipole-dipole, and hydrogen-bond interactions with the template. This moiety plays a key role in creation of selective sites while methoxysilyl groups in TMSPMA acted as crosslinkers between the template and the propylmethacrylate moiety. Moreover, a non-imprinted xerogel (NIX) was also prepared in the absence of the template for evaluating the extraction efficiency of the prepared MIX. Then, the prepared imprinted and non-imprinted xerogels were used for extraction of three selected analytes of triazines class including atrazine, ametryn, and terbutryn, which have rather similar structures. The extraction efficiency of the prepared xerogel for atrazine, the template molecule, was found to be ten times greater than the efficiency achieved by the non-imprinted one. In the meantime, the extraction efficiency ratio of MIX to NIX for ametryn and terbutryn was also rather significant (eight times). Moreover, other compounds from different classes including dicamba, mecoprop, and estriol were also analyzed to evaluate the selectivity of the prepared MIX towards triazines. The ratio of enrichment factors (EF) of MIX to NIX for atrazine, ametryn, terbutryn, dicamba, mecoprop, and estriol were about 10, 8, 8, 2, 2, and 3, respectively. The linearity for the analytes was in the range of 5-700 ?g L(-1). Limit of detection was in the range of 1-5 ?g L(-1) and the RSD% values (n = 5) were all below 6.6% at the 20 ?g L(-1) level. The developed method was also applied to real water samples and the relative recovery percentages obtained for the spiked water samples were from 92 to 104%. The CME loop, containing the prepared MIX, exhibited a rather long life time due to its remarkable solvent and mechanical stability. Even after 100 runs, no decrease in the peak areas was observed. The developed method could easily provide the possibility of preparing a selective sorbent in a unique way with the lowest possible cost and time. PMID:22752449

Bagheri, Habib; Piri-Moghadam, Hamed

2012-07-01

276

Incorporation of triethoxysilyl functionalized Coumarin 4 in sol-gel hosts  

NASA Astrophysics Data System (ADS)

A silylated Coumarin 4 (derCoum) laser dye has been incorporated over a large range of concentrations in sol-gel silica composites. Optically transparent films of derCoum and Coumarin 4 (Coum) doped silica were obtained; and their absorption and fluorescence spectra and fluorescence efficiency were measured. Dye extraction was investigated as a function of sol-gel processing conditions. Dye extraction results indicated that prehydrolysis of the derCoum and full hydrolysis of TMOS resulted in films from which the dye could not be extracted, suggesting that all the dye is bonded within the sol-gel matrix. The silylated dye films showed higher fluorescence efficiency at all concentrations with respect to the normal dye film.

Suratwala, Tayyab I.; Gardlund, Z.; Boulton, J. M.; Uhlmann, Donald R.; Watson, J.; Peyghambarian, Nasser

1994-10-01

277

Photochromic organic-inorganic composite materials prepared by sol-gel processing: properties and potentials  

NASA Astrophysics Data System (ADS)

The sol-gel method which features a low-temperature wet-chemical process opens vast possibilities to incorporating organic dyes into solid matrices for various optical applications. In this paper we present our experimental results on the sol-gel derived photochromic organic- inorganic composite (Ormocer) materials following an introductory description of the sol-gel process and a brief review on the state of the art of the photochromic solids prepared using this method. Our photochromic spirooxazine-Ormocer gels and coatings possess better photochromic response and color-change speed than the corresponding photochromic polymer coatings and similar photochemical stability to the latter. Further developments are proposed as to tackle the temperature dependence problem and further tap the potentialities of the photochromic dye-Ormocer material for practical applications.

Hou, Lisong; Mennig, Martin; Schmidt, Helmut

1994-09-01

278

Room temperature sol-gel fabrication and functionalization for sensor applications  

NASA Astrophysics Data System (ADS)

The structure and physical properties of a thin titania sol-gel layer prepared on silicon and silica surfaces were examined. Spectroscopic (FTIR, UV-VIS spectroscopy), refractive index (ellipsometry) and microscopic (light microscopy and SEM/EDS) tools were used to examine both chemical uniformity and physical uniformity of the sol-gel glass layers. The conditions for the fabrication of uniform layers were established, and room temperature dopant incorporation was examined. The absorption bands of porphyrin-containing titania sol-gel layers were characterized. By addition of a metal salt to the titania layer, it was possible to metallate the free-base porphyrin within and change the UV-VIS absorbance of the porphyrin, the basis of metal detection using porphyrins. The metalloporphyrins were detected by localized laser ablation inductive coupled mass spectroscopy (LA-ICP-MS), indicating fairly uniform distribution of metals across the titania surface.

Huyang, George; Canning, John; Petermann, Ingemar; Bishop, David; McDonagh, Andrew; Crossley, Maxwell J.

2013-06-01

279

Reflow technique for the fabrication of an elliptical microlens array in sol-gel material.  

PubMed

A simple reflow technique is employed for the fabrication of elliptical refractive microlens arrays (MLAs) on a low-cost inorganic-organic SiO2/ZrO2 sol-gel glass. The measured results show that the fabricated elliptical microlenses in a 256 x 512 array have excellent surface and dimensional qualities in terms of smoothness and uniformity. It is also shown that the optical parameters of the MLAs, such as the focal length and aperture dimension, can be accurately controlled. The proposed technique requires only an ordinary binary photomask for pattern transfer. Furthermore, the sol-gel material is found to be feasible for high-volume production, because the fabrication of MLAs can be implemented by use of cheap sol-gel materials without an etching step. PMID:14717295

He, Miao; Yuan, Xiaocong; Ngo, Nam Q; Cheong, Wai C; Bu, Jing

2003-12-20

280

Reflow technique for the fabrication of an elliptical microlens array in sol-gel material  

NASA Astrophysics Data System (ADS)

A simple reflow technique is employed for the fabrication of elliptical refractive microlens arrays (MLAs) on a low-cost inorganic-organic SiO2/ZrO2 sol-gel glass. The measured results show that the fabricated elliptical microlenses in a 256 × 512 array have excellent surface and dimensional qualities in terms of smoothness and uniformity. It is also shown that the optical parameters of the MLAs, such as the focal length and aperture dimension, can be accurately controlled. The proposed technique requires only an ordinary binary photomask for pattern transfer. Furthermore, the sol-gel material is found to be feasible for high-volume production, because the fabrication of MLAs can be implemented by use of cheap sol-gel materials without an etching step.

He, Miao; Yuan, Xiaocong; Ngo, Nam Q.; Cheong, Wai C.; Bu, Jing

2003-12-01

281

Sol-gel deposited electrochromic films for electrochromic smart window glass  

SciTech Connect

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.

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

282

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

PubMed

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

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

2010-10-15

283

Surfactant-Assisted Sol-Gel Auto-Combustion Synthesis of Sr-Hexaferrite Nano-Crystalline Powder Using Different Fuels and Basic Agents  

NASA Astrophysics Data System (ADS)

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.

Ebrahimi, S. A. S.; Hasab, M. G.; Badiei, A.

2010-03-01

284

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

NASA Astrophysics Data System (ADS)

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.

Ghobeiti Hassab, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

285

Formation of stable and strong green luminescent ZnO\\/Cd(OH)2 core-shell nanostructure by sol–gel method  

Microsoft Academic Search

Highly stable and strong green luminescent ZnO\\/Cd(OH)2 core-shell nanoparticles have been synthesised by simple sol–gel route. X-ray diffraction (XRD) and energy dispersive analysis of X-rays confirm the formation of ZnO\\/Cd(OH)2 core-shell nanoparticles. The XRD and UV–visible spectroscopy shows that ZnO core size can be efficiently engineered by varying initial precursor ratio. The photoluminescence emission spectra showed the remarkably stable and

Rupali Mishra; Raghvendra S. Yadav; Sharda S. Sanjay; Avinash C. Pandey; Chitra Dar

2010-01-01

286

Fabrication of SWNT/silica composites by the sol-gel process.  

PubMed

Single-walled carbon nanotubes (SWNTs) have successfully been incorporated into a silica matrix using the sol-gel process. The SWNTs were first functionalized with 3-aminopropyltriethoxysilane (APTES) through an amide linkage formed between the carboxylic acid groups already present on their surface and the amino group on APTES. The silane moieties were then used to form silica with and without the presence of tetramethylorthosilicate (TMOS) in a sol-gel reaction. The addition of TMOS was found to influence the molecular arrangement of the SWNT in the silica matrix and also to retard the degradation of the silica-SWNT composite. PMID:20355770

Babooram, Keshwaree; Narain, Ravin

2009-01-01

287

Whole Cell Imprinting in Sol-Gel Thin Films for Bacterial Recognition in Liquids: Macromolecular Fingerprinting  

PubMed Central

Thin films of organically modified silica (ORMOSILS) produced by a sol-gel method were imprinted with whole cells of a variety of microorganisms in order to develop an easy and specific probe to concentrate and specifically identify these microorganisms in liquids (e.g., water). Microorganisms with various morphology and outer surface components were imprinted into thin sol-gel films. Adsorption of target microorganism onto imprinted films was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations (SEM, AFM, HSEM and CLSM). The imprinted films showed high selectivity toward each of test microorganisms with high adsorption affinity making them excellent candidates for rapid detection of microorganisms from liquids.

Cohen, Tally; Starosvetsky, Jeanna; Cheruti, Uta; Armon, Robert

2010-01-01

288

Dielectric Properties of Sol-Gel Derived Barium Strontium Titanate and Microwave Sintering of Ceramics  

Microsoft Academic Search

This thesis consists of two areas of research: (1) sol-gel processing of Ba_{rm 1-x}Sr_{rm x} TiO_3 ceramics and their dielectric properties measurement; and (2) microwave versus conventional sintering of ceramics such as Al_2 O_3, Ba_{ rm 1-x}Sr_{rm x}TiO_3, Sb-doped SnO _2 and YBa_2Cu _3O_7. Sol-gel powders of BaTiO_3, SrTiO_3, and their solid solutions were synthesized by the hydrolysis of titanium

Fathi A. Selmi

1991-01-01

289

Synthesis of superhydrophobic alumina membrane: Effects of sol-gel coating, steam impingement and water treatment  

NASA Astrophysics Data System (ADS)

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.

Ahmad, N. A.; Leo, C. P.; Ahmad, A. L.

2013-11-01

290

Ion-irradiation-induced densification of zirconia sol-gel thin films  

SciTech Connect

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.

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

291

Cobalt-Doped Antimony/Tin Oxide Sol--Gels on Carbon--Silicon Layers for Modeling Sol--Gel-Carbon Fiber Interfaces  

NASA Astrophysics Data System (ADS)

This research presents a novel thermo-responsive sol--gel (dopant) combination and evaluation of the actuating responses due to various heat treatment temperatures. In this project, samples of antimony-doped tin oxide (ATO) doped with 0.1% cobalt oxide (0.1% Co2O3) sol--gel on carbon/silicon substrates are used to model the implementation of sol--gel coatings into carbon fiber composite systems. While ATO is a well-known transparent conductive material, the addition of cobalt oxide (Co2O3) alters its morphology and optical parameters at low annealing temperatures. By altering the ATO (0.1% Co2O3) heat treatment temperatures, the grain size starts to increase at 200 °C. However, when approaching 500 °C, Raman spectroscopy shows that the increase in intensity of ATO (0.1% Co2O3) is lower than ATO undoped. Scanning electron microscopy is used for imaging, and energy dispersive spectroscopy will be used for the composition analysis. Optical reflectance is reported via Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy analysis.

Richard, Brandon Demar; Alcantar, Norma; Thomas, Sylvia Wilson

2012-11-01

292

Study of the sodium phenytoin effect on the formation of sol–gel SiO 2 nanotubes by TEM  

Microsoft Academic Search

Microencapsulation is a versatile technology that allows controlling the release of different active molecules. Recently the sol–gel process has emerged like a promising method to immobilization and stabilization of biologically active compounds like enzymes, antigens, microorganisms and drugs. Porous silica and titanium dioxide materials made by low temperature sol–gel processes are promising host matrixes for encapsulation of biological molecules. The

T. López; M. Asomoza; M. Picquart; P. Castillo-Ocampo; J. Manjarrez; A. Vázquez; J. A. Ascencio

2005-01-01

293

Studies of (3-mercaptopropyl)trimethoxylsilane and bis(trimethoxysilyl)ethane sol-gel coating on copper and aluminum  

NASA Astrophysics Data System (ADS)

Bis(trimethoxysilyl)ethane (BTMSE) and (3-mercaptopropyl)trimethoxysilane (MPTMS) have been used as precursors to prepare sol-gels and hybrid sol-gel under acidic condition. From the X-ray photoelectron spectroscopy data on MPTMS sol-gel coated aluminum and copper, it has been shown that the silane film is covalently bonded to Al surface through the interfacial condensation. There is no evidence of bonding interaction between the thiol group and the Cu. The recorded reflection adsorption IR (RAIR) spectrum has provided evidence that the coating BTMSE film covalently interacts with Al. Vibrational assignments have been suggested for pure BTMSE, BTMSE sol-gel, BTMSE xerogel, and BTMSE coated Al panel based on the group frequencies and the variation of frequencies with the sample treatment conditions. The progression of condensation reaction has been observed from the IR spectra of the BTMSE sol-gel and the sol-gel coated film after the treatments at different temperatures with different lengths of time. The corrosion protection of the sol-gel coated Al and Cu has been characterized in NaCl solutions by cyclic voltammetric, potentiodynamic polarization and impedance spectroscopy methods. All these electrochemical measurements indicate that the sol-gel coated metals have better corrosion protection than the corresponding uncoated metals.

Li, Ying-Sing; Lu, Weijie; Wang, Yu; Tran, Tuan

2009-09-01

294

THERMALLY STABLE NANOCRYSTALLINE TIO2 PHOTOCATALYSTS SYNTHESIZED VIA SOL-GEL METHODS MODIFIED WITH IONIC LIQUID AND SURFACTANT MOLECULES  

EPA Science Inventory

Recently, sol-gel methods employing ionic liquids (ILs) have shown significant implications for the synthesis of well-defined nanostructured inorganic materials. Herein, we synthesized nanocrystalline TiO2 particles via an alkoxide sol-gel method employing a water-immi...

295

Electrochemical and In Vitro Behavior of Nanostructure Sol-Gel Coated 316L Stainless Steel Incorporated with Rosemary Extract  

NASA Astrophysics Data System (ADS)

The corrosion resistance of AISI 316L stainless steel for biomedical applications, was significantly enhanced by means of hybrid organic-inorganic sol-gel thin films deposited by spin-coating. Thin films of less than 100 nm with different hybrid characters were obtained by incorporating rosemary extract as green corrosion inhibitor. The morphology, composition, and adhesion of hybrid sol-gel coatings have been examined by SEM, EDX, and pull-off test, respectively. Addition of high additive concentrations (0.1%) did not disorganize the sol-gel network. Direct pull-off test recorded a mean coating-substrate bonding strength larger than 21.2 MPa for the hybrid sol-gel coating. The effect of rosemary extract, with various added concentrations from 0.012 to 0.1%, on the anticorrosion properties of sol-gel films have been characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in simulated body fluid (SBF) solution and has been compared to the bare metal. Rosemary extract additions (0.05%) have significantly increased the corrosion protection of the sol-gel thin film to higher than 90%. The in vitro bioactivity of prepared films indicates that hydroxyapatite nuclei can form and grow on the surface of the doped sol-gel thin films. The present study shows that due to their excellent anticorrosion properties, bioactivity and bonding strength to substrate, doped sol-gel thin films are practical hybrid films in biomedical applications.

Motalebi, Abolfazl; Nasr-Esfahani, Mojtaba

2013-06-01

296

Sol–gel immobilized cyano-polydimethylsiloxane coating for capillary microextraction of aqueous trace analytes ranging from polycyclic aromatic hydrocarbons to free fatty acids  

Microsoft Academic Search

Sol–gel coating containing highly polar cyanopropyl and nonpolar poly(dimethylsiloxane) components (sol–gel CN-PDMS coating) was developed for capillary microextraction (CME). The sol–gel chemistry provided an efficient means to immobilize the CN-PDMS coating by establishing chemical anchorage between the coating and the fused silica capillary inner surface. This chemical bond provided excellent thermal and solvent stability to the created sol–gel coating. For

Sameer Kulkarni; Li Fang; Khalid Alhooshani; Abdul Malik

2006-01-01

297

Synthesis and luminescence properties of ZrO 2 and ZrO 2\\/SiO 2 composites incorporating Eu(III)–phenanthroline complex prepared by a catalyst-free sol–gel process  

Microsoft Academic Search

Class I organic–inorganic hybrid materials consisting of zirconia and zirconia\\/silica matrices doped with europium(III)–1,10-phenanthroline complex were prepared by a catalyst-free sol–gel route. Two different experimental procedures were developed to incorporate the coordination compound into the matrix in order to study the possible influence of the preparation method on the optical properties of the rare earth ion. Besides, the effects of

S. Bucella; P. Riello; B. F. Scremin; P. Calvelli; R. Polloni; A. Speghini; M. Bettinelli; A. Benedetti

2004-01-01

298

Inverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol-gel combustion. The nanoparticles were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (Delta S m) calculated indirectly from magnetization isotherms in the temperature

E. Veena Gopalan; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; P. A. Joy; M. R. Anantharaman

2010-01-01

299

Preparation and complex characterization of silica holmium sol-gel monoliths.  

PubMed

Amorphous, sol-gel derived SiO(2) are known to biocompatible and bioresorbable materials. Biodegradable and inert materials containing radioactive isotopes have potential application as delivery vehicles of the beta radiation to the cancer tumors inside the body. Incorporation of holmium in the sol-gel derived SiO(2) could lead to the formation of a biodegradable material which could be used as carrier biomaterial for the radiation of radioactive holmium to the various cancer sites. The homogeneity of the prepared sol-gel silica holmium monoliths was investigated by Back Scattered Electron Imaging of Scanning Electron Microscope equipped with Energy Dispersive X-ray Analysis, X-ray Induced Photoelectron Spectroscopy and Nuclear Magnetic Resonance Spectroscopy. The biodegradation of the monoliths was investigated in Simulated Body Fluid and TRIS (Trizma pre-set Crystals) solution. The results show that by suitable tailoring of the sol-gel processing parameters holmium can be homogeneously incorporated in the silica matrix with a controlled biodegradation rate. PMID:21132520

Cacaina, D; Areva, S; Laaksonen, H; Simon, S; Ylänen, H

2010-12-05

300

Electrochemical investigation of high-performance silane sol–gel films containing clay nanoparticles  

Microsoft Academic Search

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

F. Deflorian; S. Rossi; M. Fedel; C. Motte

2010-01-01

301

Aqueous sol–gel synthesis of nanosized ceramic composite powders with metal-formate precursors  

Microsoft Academic Search

In the present investigation, a series of multicomponent silicate systems have been prepared by using an aqueous sol–gel method, where water-soluble metal formates were used as precursors. Tetraethoxy silane and metal formates were used as precursors and water was used as solvent. The gels prepared using these precursors were calcined at different temperatures and characterized by using XRD, IR, DTA,

N. N Ghosh; P Pramanik

2001-01-01

302

Immobilization of Biomolecules in Sol–Gels: Biological and Analytical Applications  

Microsoft Academic Search

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,

Vivek Babu Kandimalla; Vijay Shyam Tripathi; Huangxian Ju

2006-01-01

303

Sol-gel zirconia coatings aimed at dust suppression in aluminosilicate high temperature insulating blankets  

Microsoft Academic Search

The feasibility of reducing the amount of loftable fibres in aluminosilicate blankets by coating with sol-gel zirconia was studied. A zirconium alkoxide based solution was employed to coat small samples of blanket using a dip-coating technique. The zirconia coatings and two grades of blanket were analysed using DTA, XRD, SEM and optical microscopy techniques to characterize any reactions and phase

B. Ben-Nissan; D. Martin

1996-01-01

304

Process dependent electrical characteristics and equivalent circuit model of sol-gel based PZT capacitors  

Microsoft Academic Search

Studies of electrical properties and an equivalent circuit model is developed for ferroelectric PZT(Ti = 60%) thin film capacitors made by sol-gel spin coating with Pt electrodes. The equivalent circuit consists of two major parts: serial space charge capacitors demonstrating surface effects and parallel elements modeling the inner polycrystalline ferroelectric regions. This model is based on device physics which can

Takashi Mihara; Hitoshi Watanabe; Hiroyuki Yoshimori; C. A. Paz De Araujo; B. Melnick; L. D. McMillan

1992-01-01

305

Two substrate-confined sol-gel coassembled ordered macroporous silica structures with an open surface.  

PubMed

A sol-gel cooperative assembly method was demonstrated for the fabrication of inverse opal films with an open surface. In this method, a sol-gel silicate precursor was cooperatively assembled into the interstitial spaces of microspheres at the same time when polystyrene templates formed in between two desired substrates. Silica inverse opals with a three-dimensional ordered macroporous (3DOM) structure were obtained after selective removing the colloidal templates by calcination. The open surfaces with a high degree of interconnected porosity and extremely uniform pore size were characterized by scanning electron microscope (SEM). Optical transmission spectra reveals the existence of considerable deep band gaps of up to 70% and steep band edges of up to 6%/nm in the [111] directions of the 3DOM silica samples. A little shrinkage confirmed by transmission spectra is not larger than 3%, in consistent with the results measured by SEM, which revealing the sufficient and compact infiltration into the interstitial spaces by our confined sol-gel coassembly method. With different incidence angles, the positions of pseudogaps can be easily tuned in the wide range from 720 nm to 887 nm, agreed well with the calculated values by the Bragg law. All the results prove that the sol-gel coassembly method with two substrates confinement is a simple, low cost, convenient and versatile method for the fabrication of silica inverse opals without overlayers in large domains. PMID:23614663

Guo, Wenhua; Wang, Ming; Xia, Wei; Dai, Lihua

2013-05-07

306

A sol-gel-derived antireflective coating on optical glass for near-infrared applications  

Microsoft Academic Search

Various advantages of the sol-gel technique for the deposition of optical coatings on glass and other substrates are now well known. One single area which has been rather widely studied is the deposition of single or multilayer antireflection (AR) coatings [1-7]. For both single-layer and multilayer syustems, AR coating designs for the so-called \\

P. K. Biswas; D. Kundu; D. Ganguli

1989-01-01

307

Properties and applications of proteins encapsulated within sol–gel derived materials  

Microsoft Academic Search

The last decade has seen a revolution in the area of sol–gel-derived materials since the demonstration that these materials can be used to encapsulate biological species such as enzymes, antibodies and other proteins in a functional state. The interactions between the biomolecule and the inorganic, organic or hybrid nanocomposite material determines the degree to which the biomolecule retains its native

Wen Jin; John D Brennan

2002-01-01

308

Characterization of zirconia-based catalysts prepared by precipitation, calcination, and modified sol-gel methods  

SciTech Connect

Zirconia-based catalysts were synthesized by various methods and were evaluated for the synthesis of isobutane and isobutene from CO hydrogenation. The methods of preparation included precipitation (ZrO[sub 2] (PPT)), calcination of zirconyl salt (ZrO[sub 2] (H-0304)), and a modified sol-gel method (ZrO[sub 2] (sol-gel)). Acid-base properties of zirconia were affected by the method of preparation. The number of acidic sites on the surface follows the order of ZrO[sub 2] (PPT) > ZrO[sub 2] (sol-gel) [approx] ZrO[sub 2] (H-0304), and the number of basic sites follows ZrO[sub 2] (PPT) > ZrO[sub 2] (sol-gel) > ZrO[sub 2] (H-0304). Furthermore, adding aluminum increased the numbers of acidic and basic sites, and adding silicon increased the number of acidic sites but reduced the number of basic sites. The product distribution of CO hydrogenation depended on the acid-base properties of the catalyst, and the activity tests indicated that a large ratio of basic to acidic sites is a requirement for an active catalyst to produce isobutane and isobutene from CO hydrogenation.

Feng, Z.; Postula, W.S.; Akgerman, A.; Anthony, R.G. (Texas A and M Univ., College Station, TX (United States))

1995-01-01

309

Control of mixed oxide textural and acidic properties by the sol-gel method  

Microsoft Academic Search

Preparation of catalytic mixed oxides by sol-gel chemistry affords a degree of control over the intimacy of molecular-scale mixing — and therefore the important acidic and textural properties that depend upon mixing — that is not available by other methods. Literature examples illustrate how careful control of any one of a number of preparative parameters, including, but not limited to,

James B. Miller; Edmond I. Ko

1997-01-01

310

Application of sol-gel process to H-zeolite synthesis over amorphous aluminosilicate materials  

Microsoft Academic Search

The impregnation preparation of H-zeolite over amorphous aluminosilicate solids (cracking catalysts) is compared with new synthesis procedures based on sol-gel process. The characterization results show that the H-zeolite reacts with the intermediates of the amorphous aluminosilicate.

T. López; P. Bosch; R. Gómez; E. Basaldella; A. Kikot; E. Pereyra

1991-01-01

311

Crystalline phases of zirconia prepared by sol-gel and studied by electron microscopy  

Microsoft Academic Search

Zirconia crystalline phases evolution in ZrO2-SiO2 powders obtained by sol gel methods with different pH values, has been studied by thermal analysis and electron microscopy methods. After firing, our samples exhibited changes in tetragonal and monoclinic phases as temperature was risen. Good phase stability, an important parameter in catalytic work, was confirmed after DTA studies.

Dwight R. Acosta; Octavio Novaro; Tessy Lopez; Ricardo Gomez

1996-01-01

312

Bioactive coatings prepared by sol–gel on stainless steel 316L  

Microsoft Academic Search

This work describes the development and characterization of coatings obtained by the sol–gel technique, applied on stainless steel used in orthopaedic surgery. These coatings are applied to reduce metal corrosion and adverse reactions when implanted. Hybrid coatings of silica containing hydroxyapatite, bioactive glass and glass–ceramic particles were prepared and applied on metal substrates. The coated samples were further tested in

C. Garcia; S. Ceré; A. Durán

2004-01-01

313

Glass Coating for PDMS Microfluidic Channels by Sol-Gel Methods  

Microsoft Academic Search

Soft lithography in polydimethylsiloxane (PDMS) allows one to fabricate complex microfluidic devices easily and at low cost. However, PDMS swells in the presence of many organic solvents, which can significantly degrade the performance of PDMS microfluidic devices. We present a method to coat PDMS channels with a glass-like layer using sol-gel chemistry. As a demonstration of chemical resistance, we flow

Thao Do; Adam Abate; David Weitz; Christian Holtze

2008-01-01

314

Sol-gel deposition of buffer layers on biaxially textured metal substances  

DOEpatents

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.

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

315

Cage-Like Precursor Formation from Extensive Cyclization in Sol-Gel Inorganic Condensation Polymerization.  

National Technical Information Service (NTIS)

In the sol-gel synthesis of silica by the acid catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS), the fractal dimension, density and homogeneity of the gel depends strongly on the reaction conditions such as the pH and water concent...

L. V. Ng P. Thompson J. Sanchez A. V. McCormick

1995-01-01

316

Cage-Like Precursor Formation From Extensive Cyclization in Sol-Gel Inorganic Condensation Polymerization.  

National Technical Information Service (NTIS)

In the sol-gel synthesis of silica by the acid catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS), the fractal dimension, density and homogeneity of the gel depends strongly on the reaction conditions such as the pH and water concent...

L. V. Ng P. Thompson J. Sanchez A. V. McCormick

1995-01-01

317

Properties of sol–gel derived mesoporous aluminas as metal traps  

Microsoft Academic Search

The performance of fluid catalytic cracking (FCC) catalysts for processing heavy feedstocks is often determined by the tolerance of the catalyst to metal contaminants. Different approaches are used to manage contaminant metals. In this paper, the mesoporous sol–gel derived alumina properties are studied with respect to its behavior in the presence of nickel, after different thermal and steaming treatments. The

A. Vargas; C. Maldonado; J. A. Montoya; L. Noreña; J. Morales

2004-01-01

318

Exploring the synthesis and characterization of nanoenergetic materials from sol-gel chemistry  

Microsoft Academic Search

Nanoenergetic composite materials have been synthesized by a sol-gel chemical process where the addition of a weak base molecule induces the gelation of a hydrated metal salt solution. A proposed 'proton scavenging' mechanism, where a weak base molecule extracts a proton from the coordination sphere of the hydrated iron (III) complex in the gelation process to form iron (III) oxide\\/hydroxide,

Jeremy D. Walker

2007-01-01

319

Sol-gel-processed inorganic oxides: organic polymer composites for second-order nonlinear optical applications  

Microsoft Academic Search

A new class of promising composite materials consisting of sol-gel processed inorganic oxides and organic polymers has been developed over the last several years. These materials have been shown to be homogeneous, mechanically stable and have excellent optical properties. Second-order nonlinear optical properties are dependent upon the active chromophore being aligned within the structure. We report here the studies on

Jaroslaw W. Zieba; Yue Zhang; Paras N. Prasad; Martin K. Casstevens; Ryszard Burzynski

1992-01-01

320

Hydrophobic silica sol-gel films for biphasic electrodes and porotrodes.  

PubMed

Hydrophobic sol-gel films from methyltrimethoxysilane (MTMOS) are deposited onto glass and tin-doped indium oxide (ITO) coated glass substrates. Uniform and microporous films of ca. 200 nm thickness are obtained and investigated by scanning electron microscopy and by electrochemical techniques. From cyclic voltammograms for the oxidation of ferrocenedimethanol in aqueous 0.1 M KNO3 apparent diffusion coefficients and free volume data for processes within the film are derived and it is demonstrated that the film morphology can be controlled by the deposition timing. Two novel types of biphasic electrodes for observing liquid/liquid ion transfer reactions are introduced: (i) an ITO electrode coated with a hydrophobic sol-gel film and (ii) a hydrophobic sol-gel film on glass sputter-coated with 20 nm porous gold (porotrode). For the t-butylferrocene redox system deposited in the form of an organic liquid, very low and morphology dependent current responses are observed on modified ITO electrodes. However, the porotrode system allows biphasic electrode reactions to be driven with high efficiency and with no significant morphology effect of the hydrophobic sol-gel film. This type of nanofilm-modified electrode system will be of interest for biphasic sensor developments. PMID:15565215

McKenzie, Katy J; Niedziolka, Joanna; Paddon, Christopher A; Marken, Frank; Rozniecka, Ewa; Opallo, Marcin

2004-09-30

321

Investigation on the pressure infiltration of sol-gel processed textile ceramic matrix composites  

Microsoft Academic Search

A pressure infiltration apparatus was used to fabricate textile ceramic matrix composites using sol-gel processing with added solid particles. A parabolic rate kinetics model for the infiltration process has been developed and experimentally verified. Darcy's law and a global permeability of the whole material system were adopted in the model. Experiments were conducted using both a 3-d angle interlock and

Hsien-Kuang Liu

1996-01-01

322

Sol-Gel Processed Multifunctional Organic Polymer-Inorganic Oxide Composites for Electronics and Photonics.  

National Technical Information Service (NTIS)

This document includes a detailed description of efforts to develop sol-gel polymer composites for use in the fields of electronics and photonics. The central aim of the SBIR Phase I effort was to develop a multifunctional composite containing both oxides...

M. K. Casstevens R. Burzynski

1992-01-01

323

Novel Sol-Gel Composite Second Harmonic Generator and Electrooptic Modulator.  

National Technical Information Service (NTIS)

This document is submitted as the second annual technical report for contract No. F49620-92-C0046 and presents LPT's work on the preparation of second-order NLO composite materials. The approach employed in this work is to use NLO ormosils and sol-gel pre...

R. Burzynski M. Casstevens

1995-01-01

324

Low-density nanoporous iron foams synthesized by sol-gel autocombustion  

NASA Astrophysics Data System (ADS)

Nanoporous iron metal foams were synthesized by an improved sol-gel autocombustion method in this report. It has been confirmed to be pure phase iron by X-ray diffraction measurements. The nanoporous characteristics were illustrated through scanning electron microscope and transmission electron microscope images. Very low density and quite large saturation magnetization has been performed in the synthesized samples.

Hua, Zhenghe; Deng, Yu; Li, Kenan; Yang, Shaoguang

2012-02-01

325

Investigation of etch pits on KDP crystals with porous sol-gel coatings  

NASA Astrophysics Data System (ADS)

We have investigated etch-pit formation on potassium dihydrogen phosphate (KDP) crystals with porous anti-reflective coatings. Etch pits develop beneath the sol-gel coatings after exposure to ambient humidity. The etch pits are homogeneously distributed with a density and an average size governed by the relative humidity and the coating thickness. Furthermore, the etch pits are self-similar in shape and possess facets corresponding to low-energy planes of KDP. Results from optical microscopy, light scattering, and atomic force microscopy support the following model for etch-pit formation in this system. Water adsorbed from the environment into the porous sol-gel coating contacts the crystal surface, causing etch-pit nucleation at high undersaturation. The plume of KDP rising from an etch pit slowly diffuses laterally, reducing the undersaturation and shutting off nucleation in the surrounding area. Because surface kinetics are rapid compared to mass transport through the sol-gel, etch pits continually undergo equilibration to maintain a low-energy geometry and generate an average spacing. Growth continues until the reservoir of water in the sol-gel is saturated with KDP. Coarsening is only observed in high relative humidity environments.

Wheeler, E. K.; Whitman, P. K.; Land, T. A.; De Yoreo, J.; Thorsness, C. B.; McWhirter, J. H.; Hanna, M. L.; Miller, E. L.

326

Integrated ultrasonic transducers made by the sol gel spray technique for structural health monitoring  

Microsoft Academic Search

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

M. Kobayashi; C.-K. Jen; J.-F. Moisan; N. Mrad; S. B. Nguyen

2007-01-01

327

Integrated ultrasonic transducers made by the sol–gel spray technique for structural health monitoring  

Microsoft Academic Search

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

M Kobayashi; C-K Jen; J-F Moisan; N Mrad; S B Nguyen

2007-01-01

328

PRODUCTION OF ALKYL ESTERS BY A PHYLLOSILICATE SOL-GEL IMMOBILIZED LIPASE FROM PSEUDOMONAS CEPACIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lipase PS-30 from Pseudomonas cepacia was immobilized within a phyllosilicate sol-gel matrix and its esterification activity compared to the commercial immobilized lipases, papain, lipase L-2, and IM60. Immobilized lipase PS-30 (IM-PS30) had good alcoholysis activity for tallow using ethanol (315 U...

329

Investigation of an automated cleaning system for LMJ coating sol-gel process  

NASA Astrophysics Data System (ADS)

The French Commission for Atomic Energy is currently involved in a project which consists in the construction of a 2MJ/500TW (351nm) laser, so called LMJ (Megajoule-class laser) devoted to Inertial Confinement Fusion (ICF) research in France[1]. For this high power lasers, the sol-gel process[2] has been selected for 95% of laser optical coated area because of room temperature and atmospheric pressure conditions with guarantee for high optical and laser induced damage threshold (LIDT) performances at a low cost compared to conventional vacuum deposition processes. The production rate of sol-gel coatings for the LMJ optical components will require an automated cleaning surface step during sol-gel process. We are investigating a spraying system and wash cycles compatible with the two sol-gel deposition methods: dip and laminar-flow coating. The challenge is to achieve the same cleaned optical surfaces as manual process without using organic solvents. Therefore the main specifications of the cleaning quality are the following ones: a high surface energy over all optical sides (up to 400×400 mm2 area) and no degradation of polished sides (surface defects and LIDT). We present the metrologies carried out and the first results obtained from different wash cycles. These one mainly consist in measurement of contact angles, defects inspections under specific lighting conditions and LIDT tests. Several parameters of wash cycles have been investigated such as washing and rinsing temperatures, water quality, type and concentration of detergents, wettability effects...

Lavastre, E.; Fontaine, S.; Bergez, R.; Wender, P.; Cormont, P.; Pellegrini, C.; Beaurain, L.; Belleville, P.

2008-09-01

330

Initial responses of human osteoblasts to sol-gel modified titanium with hydroxyapatite and titania composition.  

PubMed

Sol-gel thin films of hydroxyapatite (HA) and titania (TiO(2)) have received a great deal of attention in the area of bioactive surface modification of titanium (Ti) implants. Sol-gel coatings were developed on Ti substrates of pure HA and TiO(2) and two composite forms, HA+10% TiO(2) and HA+20% TiO(2), and the biological properties of the coatings were evaluated. All the coating layers exhibited thin and homogeneous structures and phase-pure compositions (either HA or TiO(2)). Primary human osteoblast cells showed good attachment, spreading and proliferation on all the sol-gel coated surfaces, with enhanced cell numbers on all the coated surfaces relative to uncoated Ti control at day 1, as observed by MTT assay and scanning electron microscopy. Cell attachment rates were also enhanced on the pure HA coating relative to control Ti. The pure HA and HA+10% TiO(2) composite coating furthermore enhanced proliferation of osteoblasts at 4 days. Moreover, the gene expression level of several osteogenic markers including bone sialoprotein and osteopontin, as measured by RT-PCR at 24h, was shown to vary according to coating composition. These findings suggest that human primary bone cells show marked and rapid early functional changes in response to HA and TiO(2) sol-gel coatings on Ti. PMID:16829219

Harle, Jamie; Kim, Hae-Won; Mordan, Nicky; Knowles, Jonathan C; Salih, Vehid

2006-07-10

331

Sol-Gel Synthesis and Characterization of Neodymium-Ion Doped Nanostructured Titania Thin Films.  

National Technical Information Service (NTIS)

Nd doped TiO2 nanostructured thin films were prepared by sol-gel technique on quartz and Si substrates using TiCl4 precursor. As-deposited amorphous films were annealed to form anatase phase in the thin films. The film grain size increased with annealing ...

A. Burns C. Baker S. I. Shah W. Li

2001-01-01

332

Glucose concentration determination based on silica sol–gel encapsulated glucose oxidase optical biosensor arrays  

Microsoft Academic Search

Optical biosensor arrays for rapidly determining the glucose concentrations in a large number of beverage and blood samples were developed by immobilizing glucose oxidase (GOD) on oxygen sensor layer. Glucose oxidase was first encapsulated in silica based gels through sol–gel approach and then immobilized on 96-well microarrays integrated with oxygen sensing film at the bottom. The oxygen sensing film was

Gang Chang; Yoshiro Tatsu; Tatsushi Goto; Hiromasa Imaishi; Kenichi Morigaki

2010-01-01

333

A Sol-Gel-Modified Poly(methyl methacrylate) Electrophoresis Microchip with a Hydrophilic Channel Wall  

SciTech Connect

A sol-gel method was employed to fabricate a poly(methyl methacrylate) (PMMA) electrophoresis microchip that contains a hydrophilic channel wall. To fabricate such a device, tetraethoxysilane (TEOS) was injected into the PMMA channel and was allowed to diffuse into the surface layer for 24 h. After removing the excess TEOS, the channel was filled with an acidic solution for 3 h. Subsequently, the channel was flushed with water and was pretreated in an oven to obtain a sol-gel-modified PMMA microchip. The water contact angle for the sol-gel-modified PMMA was 27.4° compared with 66.3° for the pure PMMA. In addition, the electro-osmotic flow increased from 2.13×10-4 cm2 V-1 s-1 for the native-PMMA channel to 4.86×10-4 cm2 V-1 s-1 for the modified one. The analytical performance of the sol-gel-modified PMMA microchip was demonstrated for the electrophoretic separation of several purines, coupled with amperometric detection. The separation efficiency of uric acid increased to 74 882.3 m-1 compared with 14 730.5 m-1 for native-PMMA microchips. The result of this simple modification is a significant improvement in the performance of PMMA for microchip electrophoresis and microfluidic applications.

Chen, Gang; Xu, Xuejiao; Lin, Yuehe; Wang, Joseph

2007-07-27

334

Organic-Inorganic CO2 Selective Membranes Prepared by the Sol-Gel Process  

Microsoft Academic Search

Composite membranes prepared from mixtures of 3-glycidoxypropyl trimethoxysilane (GPTMS) and different diamines containing polyether segments were synthesized by the sol-gel process. The membranes were obtained by coating asymmetric porous polyacrylonitrile (PAN) supports with the silane solutions. The composite membranes were characterized by single and mixed gas permeation and by atomic force microscopy. The selectivity increased by increasing the molecular weight

C. Nistor; S. Shishatskiy; M. Popa; S. P. Nunes

2009-01-01

335

Assessment of molecularly imprinted sol–gel materials for selective room temperature phosphorescence recognition of nafcillin  

Microsoft Academic Search

Sol–gel imprinted materials were prepared against nafcillin, a semisynthetic ?-lactamic antibiotic employed in the treatment of serious infections caused by penicillinase-producing staphylococci. Two approaches were addressed for preparation of the imprinted materials and the controls: as conventional monoliths, which were ground and sieved to a desired particle size for rebinding analysis, and as films on supporting glass slides. The specific

A Fernández-González; R Bad??a La??ño; M. E Diaz-Garc??a; L Guardia; A Viale

2004-01-01

336

Characterization of doped BST thin films prepared by a modified sol gel method  

Microsoft Academic Search

Barium strontium titanate (BST) films have been fabricated using a modified sol gel method. The crystallization temperature was 100°C higher than that for lead zirconate titanate. The electrical properties improved when multiple rapid thermal processing was used. The dielectric constant of BST films was of the order of 250 which was characteristic of a small grain size and the presence

Miroslav Sedlar; Michael Sayer; Vasant Chivukula

1995-01-01

337

Fabrication of hollow silica aerogel spheres by a droplet generation method and sol--gel processing  

Microsoft Academic Search

A system was designed to produce hollow silica aerogel spheres by combining a droplet generation method with sol--gel processing. Simultaneous passage of an alkoxide solution and a fill gas, through a dual-nozzle system, formed a continuous stream of hollow droplets in the fluid state. The spherical droplets were levitated in a basic atmosphere containing ammonia which converted the sol into

N. K. Kim; K. Kim; D. A. Payne; R. S. Upadhye

1989-01-01

338

Fabrication of Hollow Silica Aerogel Micospheres Using Droplet Generation Technique and Sol-Gel Process.  

National Technical Information Service (NTIS)

A system was designed to produce hollow silica aerogel microspheres by combining a droplet generation technique and a sol-gel process. In the system, a simultaneous passage of an alkoxide solution and a fill gas through a dual-nozzle system found a contin...

N. K. Kim K. Kim D. A. Payne R. S. Upadhye

1988-01-01

339

Magnetic resonance as a structural probe of a uranium (VI) sol-gel process  

SciTech Connect

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.

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

340

Magnetic resonance as a structural probe of a uranium (VI) sol-gel process  

SciTech Connect

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.

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

341

NonAqueous Battery Systems  

Microsoft Academic Search

Lithium and sodium are light and highly electronegative elements which form the basis of anodes for high-energy-density battery systems. Their high chemical reactivity requires the use of ionic conductors based on non-aqueous solvents, polymers, solid electrolytes or fused salts. An associated range of cathode materials enables cells to be fabricated with open-circuit voltages from 1.5 to 4.0 V. Practical non-aqueous

Colin A. Vincent

1996-01-01

342

Sol-gel processes and materials. January 1970-August 1989 (Citations from the US Patent data base). Report for January 1970-August 1989  

SciTech Connect

This 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, cataylsts and catalyst supports, nuclear fuels preparation, abrasives for grinding wheels, Sol-Gel production of microspheres, alumina composites, photographic materials, and dental materials. (This updated bibliography contains 108 citations, 37 of which are new entries to the previous edition.)

Not Available

1989-09-01

343

Sol-gel processes and materials. November 1971-October 1989 (Citations from the US Patent data base). Report for November 1971-October 1989  

SciTech Connect

This 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, cataylsts and catalyst supports, nuclear fuels preparation, abrasives for grinding wheels, sol-gel production of microspheres, alumina composites, photographic materials, and dental materials. (This updated bibliography contains 120 citations, 12 of which are new entries to the previous edition.)

Not Available

1990-01-01

344

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in sol–gel-derived tin oxide\\/gelatin composite films  

Microsoft Academic Search

Horseradish peroxidase (HRP) was immobilized into a new type of sol–gel-derived nano-sized tin oxide\\/gelatin composite film (SnO2 composite film) using a sol–gel film\\/enzyme\\/sol–gel film “sandwich” configuration. Direct electrochemistry and electrocatalysis of HRP incorporated into the composite films were investigated. HRP\\/SnO2 composite film exhibited a pair of stable and quasi-reversible cyclic voltammetric peaks for the HRP Fe(III)\\/HRP Fe(II) redox couple with

Nengqin Jia; Qin Zhou; Ling Liu; Manming Yan; Zhiyu Jiang

2005-01-01

345

A fiber-optic pH sensor prepared using a base-catalyzed organo-silica sol–gel  

Microsoft Academic Search

Fiber-optic pH sensors have been fabricated using fluorescein isothiocyanate immobilized in a base-catalyzed organo-silica sol–gel film. Hydrophilic sol–gel coatings are made by co-polymerizing tetraethylorthosilicate and silanol-terminated polydimethylsiloxane with 3-aminopropyltriethoxysilane (APTES) and\\/or 3-glycidoxypropyltrimethoxysilane. Unlike current techniques, which describe acid-catalyzed sol–gels, a base catalyst was found to be better suited for producing optically transparent gels when high concentrations of APTES were used.

Delana A Nivens; Yunke Zhang; S. Michael Angel

1998-01-01

346

Sol-gel synthesis of nanocomposite materials based on lithium niobate nanocrystals dispersed in a silica glass matrix  

NASA Astrophysics Data System (ADS)

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 Li2O-Nb2O5-SiO2 system is reported. In this route, LiNO3, NbCl5 and Si(OC2H5)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 LiNbO3 as only crystallizing phase. LiNbO3-SiO2 nanocomposite thin films on Si-SiO2 and Al2O3 substrates were grown. The LiNbO3 average size, increasing with the annealing temperature, was 27 nm for a film of composition 10Li2O-10Nb2O5-80SiO2 heated 2 h at 800 °C. Electrical investigation revealed that the nanocrystals size strongly affects the film conductivity and the occurrence of hysteretic current-voltage curves.

Marenna, Elisa; Aruta, Carmela; Fanelli, Esther; Barra, Mario; Pernice, Pasquale; Aronne, Antonio

2009-05-01

347

Sol-gel synthesis of nanocomposite materials based on lithium niobate nanocrystals dispersed in a silica glass matrix  

SciTech Connect

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.

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

348

Sol-gel synthesis and luminescent properties of nanocrystalline YAP:Mn  

NASA Astrophysics Data System (ADS)

The work describes results of synthesis of Mn-doped YAP nanocrystalline samples by the sol-gel method and characterization of the material by X-ray powder diffraction, scanning electron microscopy and luminescence techniques. It was revealed that obtained in such a way YAP samples posses rather poor radiation storage properties that is interpreted by the uniform near-equilibrium synthesis conditions that does not allow formation of YAl antisite ions required for electrons trapping. On the other hand, the sol-gel method can be suggested as a suitable technique for obtaining of highly stoichiometric and not defected structure material without parasitic charge capturing and recombination processes that is very essential e.g. for scintillator materials.

Baran, M.; Zhydachevskii, Ya.; Suchocki, A.; Reszka, A.; Warchol, S.; Diduszko, R.; Paj?czkowska, A.

2012-02-01

349

Multi-level diffractive optical elements produced by excimer laser ablation of sol-gel.  

PubMed

Material ablation by excimer laser micromachining is a promising approach for structuring sol-gel materials as we demonstrate in the present study. Using the well-known direct etching technique, the behaviour of different hybrid organic/inorganic self-made sol-gel materials is examined with a KrF* laser. Ablated depths ranging from 0.1 to 1.5 microm are obtained with a few laser pulses at low fluence (< 1 J/cm(2)). The aim is to rapidly transfer surface relief multi-level diffractive patterns in such a substrate, without intermediate steps. The combination with the 3D profilometry technique of coherence probe microscopy permits to analyse the etching process with the aim of producing multi-level Diffractive Optical Elements (DOE). Examples of four-level DOEs with 10 microm square elementary cells are presented, as well as their laser reconstructions in the infrared. PMID:18773015

Neiss, Estelle; Flury, Manuel; Mager, Loïc; Rehspringer, Jean-Luc; Fort, Alain; Montgomery, Paul; Gérard, Philippe; Fontaine, Joël; Robert, Stéphane

2008-09-01

350

Sol-gel coatings for high power laser optics-past, present and future  

SciTech Connect

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.

Thomas, I.M.

1993-12-21

351

A sol-gel method for growing superconducting MgB2 films  

NASA Astrophysics Data System (ADS)

In this paper we report a new sol-gel method for the fabrication of MgB2 films. Polycrystalline MgB2 films were prepared by spin-coating a precursor solution of Mg(BH4)2 diethyl ether on (001)Al2O3 substrates followed with annealing in Mg vapor. In comparison with the MgB2 films grown by other techniques, our films show medium qualities including a superconducting transition temperature of TC ~ 37 K, a critical current density of JC(5 K, 0 T) ~ 5 × 106 A cm - 2, and a critical field of HC2(0) ~ 19 T. Such a sol-gel technique shows potential in the commercial fabrication of practically used MgB2 films as well as MgB2 wires and tapes.

Chen, L. P.; Zhang, C.; Wang, Y. B.; Wang, Y.; Feng, Q. R.; Gan, Z. Z.; Yang, J. Z.; Li, X. G.

2011-01-01

352

The Physics of Evaporation-Induced Assembly of Sol-Gel Materials  

SciTech Connect

Remarkable materials ordered at the nanoscale emerge when a sol-gel solution becomes co-organized with a surfactant. At sufficiently high concentration, the surfactant forms crystalline or liquid-crystalline arrays of micelles in the presence of the sol-gel, and as gelation proceeds the arrays become locked into the gel. Recent experiments demonstrate that the degree of order in the resulting mesoporous ceramic phase can be enhanced and controlled by continuous dip coating in which the solution, initially dilute, evolves through the critical micelle concentration by steady-state evaporation. The long-range order and microstructural orientation in these films suggest that the propagation of a critical-micelle-concentration transition front, with large physico-chemical gradients, promotes oriented self assembly of surfactant aggregates. This steep-gradient view is supported by results from unsteady evaporation of aerosols of similar solutions, in which internally well-ordered but complex particles are formed.

HURD,ALAN J.; STEINBERG,LEV

2000-07-24

353

Liquid crystalline phase behavior and sol-gel transition in aqueous halloysite nanotube dispersions.  

PubMed

The liquid crystalline phase behavior and sol-gel transition in halloysite nanotubes (HNTs) aqueous dispersions have been investigated by applying polarized optical microscopy (POM), macroscopic observation, rheometer, small-angle X-ray scattering, scanning electron microscopy, and transmission electron microscopy. The liquid crystalline phase starts to form at the HNT concentration of 1 wt %, and a full liquid crystalline phase forms at the HNT concentration of 25 wt % as observed by POM and macroscopic observation. Rheological measurements indicate a typical shear flow behavior for the HNT aqueous dispersions with concentrations above 20 wt % and further confirm that the sol-gel transition occurs at the HNT concentration of 37 wt %. Furthermore, the HNT aqueous dispersions exhibit pH-induced gelation with more intense birefringence when hydrochloric acid (HCl) is added. The above findings shed light on the phase behaviors of diversely topological HNTs and lay the foundation for fabrication of the long-range ordered nano-objects. PMID:24070131

Luo, Zhiqiang; Song, Hongzan; Feng, Xiaorui; Run, Mingtao; Cui, Huanhuan; Wu, Licun; Gao, Jungang; Wang, Zhigang

2013-09-26

354

Phenol biodegradation by fungal cells immobilized in sol-gel hybrids.  

PubMed

The capability of cells of the fungus Aspergillus awamori, either free or immobilized in hybrid sol-gel material cells, for phenol biodegradation was demonstrated. Phenol was present in the reaction mixture as the sole carbon and energy source, and its decomposition was followed in repeated batch degradation experiments. Atomic force microscopy provided information on the development of self-organizing structures in the materials synthesized by the sol-gel method. Phenol biodegradation was mediated only by the fungal cells, and no absorption by the hybrid matrix was observed. Ten cycles of phenol biodegradation using the immobilized cells system were conducted during which up to 2000 mg l(-1) phenol was completely decomposed. Immobilized cells degraded phenol at 8.33 mg h(-1), twice as fast as free cells. The good performance of the immobilized fungal cell system is promising for the development of an efficient technology for treating phenol-containing waste waters. PMID:23659173

Tsekova, Kolishka V; Chernev, Georgi E; Hristov, Alexander E; Kabaivanova, Lyudmila V

355

Physically incorporated extraction phase of solid-phase microextraction by sol-gel technology.  

PubMed

A sol-gel method for the preparation of solid-phase microextraction (SPME) fiber was described and evaluated. The extraction phase of poly(dimethysiloxane) (PDMS) containing 3% vinyl group was physically incorporated into the sol-gel network without chemical bonding. The extraction phase itself is then partly crosslinked at 320 degrees C, forming an independent polymer network and can withstand desorption temperature of 290 degrees C. The headspace extraction of BTX by the fiber SPME was evaluated and the detection limit of o-xylene was down to 0.26 ng/l. Extraction and determination of organophosphorus pesticides (OPPs) in water, orange juice and red wine by the SPME-GC thermionic specified detector (TSD) was validated. Limits of detection of the method for OPPs were below 10 ng/l except methidathion. Relative standard deviations (RSDs) were in the range of 1-20% for pesticides being tested. PMID:16289084

Liu, Wenmin; Hu, Yuan; Zhao, Jinghong; Xu, Yuan; Guan, Yafeng

2005-11-10

356

Effect of sol-gel modifications on formation and morphology of nanocrystalline lanthanum aluminate  

SciTech Connect

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.

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

357

Sol gel based fiber optic sensor for blook pH measurement  

SciTech Connect

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.

Grant, S. A.; Glass, R. S.

1996-12-19

358

A Review of Photocatalysts Prepared by Sol-Gel Method for VOCs Removal  

PubMed Central

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.

Tseng, Ting Ke; Lin, Yi Shing; Chen, Yi Ju; Chu, Hsin

2010-01-01

359

Transparent ultralow-density silica aerogels prepared by a two-step sol-gel process  

SciTech Connect

Conventional silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels <.020 g/cc. We have developed a two-step sol-gel process that circumvents the limitations of the conventional process and allows the formation of ultralow-density gels in a matter of hours. we have found that the gel time is dependent on the catalyst concentration. After supercritical extraction, the aerogels are transparent, uncracked tiles with densities as low as .003 g/cc. 6 figs., 11 refs.

Tillotson, T.M.; Hrubesh, L.W.

1991-09-01

360

Luminescence of cryptate-type Eu3+ complexes incorporated in inorganic and ormocer sol gel matrices  

NASA Astrophysics Data System (ADS)

Two new complexes of Eu-bipyridine (Eu-AA and Eu-BB) were incorporated into sol gel derived thin films based on zirconia oxide and organically modified sol gel hybrid zirconia silica urethane ormocer (ZSUR). The absorption and the emission intensities of the composites were compared to the intensity of the Eu oxide doped films and to the other complexes studied recently. The site symmetry of the Eu complexes and Eu oxide in used matrices were studied as well. The intensification of fluorescence, as compared to europium oxide, value was increased by a factor of 64 in amido amino complex (Eu-AA), and of 2044 in fluorine complex (Eu-BB) as a result of efficient charge transfer from the combined ligand-europium state to europium high ligand levels. The lifetimes from the 5D0 state of the complexes are measured and the results explained.

Reisfeld, R.; Saraidarov, T.; Gaft, M.; Pietraszkiewicz, M.

2007-01-01

361

Silicon diffusion in sol-gel derived isotopically enriched silica glasses  

SciTech Connect

We performed silicon diffusion experiments with sol-gel derived isotopically enriched silica glasses at temperatures between 1050 deg. C and 1300 deg. C. The diffusion profiles were measured by means of time-of-flight secondary ion mass spectrometry. Samples annealed in closed silica ampoules under argon or dry air reveal enhanced Si diffusion compared to Si diffusion in fused silica. On the other hand, annealing in a large alumina tube under {sup 18}O{sub 2} ambient yields Si and O diffusion coefficients which approach the results for thermally grown SiO{sub 2}. The enhanced Si diffusion in sol-gel derived glass is proposed to be due to water residues which lead to the formation of silanol SiOH groups.

Bracht, H.; Staskunaite, R.; Haller, E.E.; Fielitz, P.; Borchardt, G.; Grambole, D. [Institute of Material Physics and Sonderforschungsbereich 458 and Center of Nanotechnology (CeNTech), University of Muenster (Germany); Institute of Metallurgy, Technical University of Clausthal (Germany); Institute of Ion Beam Physics and Materials Research, Forschungszentrum Rossendorf (Germany)

2005-02-15

362

Cross-condensation reactions in an organically modified silica sol-gel  

SciTech Connect

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.

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

363

Reversible Sol-Gel Transitions in Aqueous Solutions of N-Isopropylacrylamide Ionic Copolymers  

SciTech Connect

Ionic copolymers of N-isopropylacrylamide (NIPA) exhibiting sol-gel transitions in aqueous solutions were investigated. The studies were aimed at understanding of the structure-property relationship in design of injectable, in situ forming gels for potential biomedical applications in delivery of therapeutics and tissue engineering. Aqueous solutions of NIPA ionic copolymers were found to flow freely at ambient temperatures and formed soft gels with controlled syneresis above 32°C, the lower critical solution temperature of NIPA. The sol-gel transitions and temperature dependent properties of the resulting gels were analyzed using dynamic rheometry, UV and IR spectrometry, and were found to be controlled by the molecular weight and composition of copolymers, ionization state of comonomers, and composition of aqueous solvent.

Krzyminski, Karol J.; Jasionowski, Marek; Gutowska, Anna

2008-04-01

364

Synthesis and characterization of ordered and disordered polycrystalline La2NiMnO6 thin films by sol-gel.  

PubMed

Polycrystalline La(2)NiMnO(6) thin films are prepared on Pt/Ti/SiO(2)/Si substrates by the sol-gel method. Through controlling the processing parameters, the cation ordering can be tuned. The disordered and ordered thin films exhibit distinct differences for crystal structures as well as properties. The crystal structure at room temperature characterized by X-ray diffraction and Raman spectra is suggested to be monoclinic (P2(1)/n) and orthorhombic (Pbnm) for the ordered and disordered thin films, respectively. The ferromagnetic-paramagnetic transition is 263 K and 60 K for the ordered and disordered samples respectively, whereas the saturation magnetic moment at 5 K is 4.9 ?(B) fu(-1) (fu = formula unit) and 0.9 ?(B) fu(-1). The dielectric constant as well as magnetodielectric effect is higher for the ordered La(2)NiMnO(6) thin films. The magnetodielectric effect for the ordered thin film is dominantly contributed to the intrinsic coupling of electric dipole ordering and fluctuations and magnetic ordering and fluctuations, while it is mainly contributed to Maxwell-Wagner (M-W) effects for the disordered thin film. The successful achievements of ordered and disordered polycrystalline La(2)NiMnO(6) thin films will provide an effective route to fabricate double-perovskite polycrystalline thin films by the sol-gel method. PMID:22910689

Zhang, Zhiqing; Jian, Hongbin; Tang, Xianwu; Yang, Jie; Zhu, Xuebin; Sun, Yuping

2012-08-21

365

Epitaxial growth of La2Zr2O7 thin films on rolled Ni-substrates by sol-gel process for high Tc superconducting tapes  

NASA Astrophysics Data System (ADS)

A solution process was used to grow epitaxial La2Zr2O7 (LZO) buffer layers on roll-textured Ni (100) substrates to produce YBa2Cu3O7-? (YBCO)-coated conductors. The LZO precursor solution was prepared by an all alkoxide sol-gel route using mixed metal methoxyethoxides in 2-methoxyethanol. The partially hydrolyzed solution was either spin-coated or dip-coated onto the textured Ni substrates. The amorphous thin film was then heat treated at 1150°C under (96%)Ar/(4%)H2 atmosphere for 1 h. X-ray diffraction (XRD) of the buffer layer indicated a strong c-axis orientation on the Ni (100) substrate. The LZO (222) pole figure revealed a single cube-on-cube texture. SEM images of the LZO buffer layer showed a dense microstructure without cracks. The YBCO deposited on the sol-gel LZO-buffered Ni substrates with sputtered YSZ and CeO2 top layers had a critical current density of 480,000 A/cm2 at 77 K and self-field.

Chirayil, T. G.; Paranthaman, M.; Beach, D. B.; Lee, D. F.; Goyal, A.; Williams, R. K.; Cui, X.; Kroeger, D. M.; Feenstra, R.; Verebelyi, D. T.; Christen, D. K.

2000-07-01

366

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)

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 Ni1-xCoxMoO4, 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.

Maione, Andrea; Devillers, Michel

2004-07-01

367

Synthesis of the Nanocrystalline Nickel Ferrite by a Novel Mechano Sol-Gel Auto-Combustion Method  

NASA Astrophysics Data System (ADS)

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.

Shahmirzaei, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

368

Sol-gel nanocasting synthesis of patterned hierarchical LaFeO3 fibers with enhanced catalytic CO oxidation activity  

NASA Astrophysics Data System (ADS)

Hierarchical LaFeO3 fibers were prepared by a sol-gel nanocasting method using a cotton cloth as the template. The resulting LaFeO3 fibers inherited the initial network morphology of the template very well and showed enhanced catalytic CO oxidation activity and satisfactory stability compared to the counterpart particles prepared by the conventional sol-gel method.Hierarchical LaFeO3 fibers were prepared by a sol-gel nanocasting method using a cotton cloth as the template. The resulting LaFeO3 fibers inherited the initial network morphology of the template very well and showed enhanced catalytic CO oxidation activity and satisfactory stability compared to the counterpart particles prepared by the conventional sol-gel method. Electronic supplementary information (ESI) available: Materials, detailed experimental procedures and characterization, XRD patterns, SEM and TEM images, BET data and XPS spectra. See DOI: 10.1039/c0nr00760a

Li, Pengna; Hu, Xianluo; Zhang, Lei; Dai, Hongxing; Zhang, Lizhi

2011-03-01

369

Fabrication by sol-gel method of Y-Ba-Cu-O pellets with superconducting transition temperature above 90 K.  

National Technical Information Service (NTIS)

Specimens of YBCO superconducting compounds have been fabricated either starting from solid state reactions or employing a modified sol-gel technique. Both kind of samples have been tested by X-ray diffraction, microprobe analysis and resistance vs temper...

G. Arcangeli R. Vatteroni R. Fava

1987-01-01

370

Sol-gel silica planar waveguide doped with green fluorescent protein for in-line biosensors  

Microsoft Academic Search

The authors report in-line detection of green fluorescent light from planar waveguide biosensors made of sol-gel silica and doped with green fluorescent protein (GFP). GFP is immobilized on the surface of polystyrene microbeads. Green fluorescence, with a center wavelength of 509 nm, is observed for an excitation with a pump laser power of 3 mW at 488 nm wavelength. GFP

Y. Enami; T. Fukuda; S. Suye

2007-01-01

371

Enhancement of electrochemical performance of lithium iron phosphate by controlled sol–gel synthesis  

Microsoft Academic Search

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.

Jae-Kwang Kim; Jae-Won Choi; Ghanshyam S. Chauhan; Jou-Hyeon Ahn; Gil-Chan Hwang; Jin-Beom Choi; Hyo-Jun Ahn

2008-01-01

372

ITO films on glass substrate by sol–gel technique: synthesis, characterization and optical properties  

Microsoft Academic Search

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,

E. Celik; U. Aybarc; M. F. Ebeoglugil; I. Birlik; O. Culha

2009-01-01

373

Titanium dioxide films for photovoltaic cells derived from a sol–gel process  

Microsoft Academic Search

We present a sol–gel process which is used to prepare thin titanium dioxide nanoparticle layers by spin-coating or doctor-blading techniques. After being sensitized with a dye, the films are used for the transport of electrons in photoelectrochemical solar cells. The titanium dioxide particles have diameters of about 100nm. A comparison with screen-printed layers consisting of particles with a typical size

Yongxiang Li; Jürgen Hagen; Winfried Schaffrath; Peter Otschik; Dietrich Haarer

1999-01-01

374

Fabrication of PZT sol gel composite ultrasonic transducers using batch fabrication micromolding  

Microsoft Academic Search

A new micromolding technique for fabricating high-frequency (>20 MHz) ultrasound transducers has been developed. The technique combines sol gel processing with an epoxy-based, photo-resist Su-8 micromold to form miniature PZT structures. An advantage of this technique as compared to more traditional lithographic galvanforming and abforming (LIGA) processing is that the intermediate step of producing a nickel-plated mold is avoided. Instead,

Guofeng Pang; Michael Sayer; Geoffrey R. Lockwood; Michael Watt

2006-01-01

375

Improvement of yeast biochip sensitivity using multilayer inorganic sol–gel substrates  

Microsoft Academic Search

Today, microarray fluorescence detection is still limited because a great proportion of hybrids remain undetectable. In this paper we describe sol–gel optical multilayers (stacks of low- and high-index layers) deposited on glass slides which increase the fluorescence of DNA microarrays and favour the detection of fluorescent targets. An alternative to the expensive and time-consuming physical vapour deposition technology is proposed.

B. Fouqué; A. G. Brachet; S. Gétin; P. Pégon; P. Obeïd; G. Delapierre; F. Chatelain

2007-01-01

376

Active fibers from sol-gel derived granulated silica: state of the art and potential  

Microsoft Academic Search

In the recent past we have studied the granulated silica method as a versatile and cost effective way of fiber preform production. We have used the sol-gel technology combined with a laser-assisted remelting step to produce high homogeneity Rare Earth or Transition Metal - activated microsized particles for the fiber core. For the fiber cladding pure or index-raised granulated Silica

Valerio Romano; Frederic Sandoz

2010-01-01

377

Solid oxide fuel cells developed by the sol-gel process for oxygen generation  

Microsoft Academic Search

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)

Joshua S. Finch

2008-01-01

378

Immunoaffinity chromatography of polycyclic aromatic hydrocarbons in columns prepared by the sol-gel method  

Microsoft Academic Search

This paper describes the immobilisation of the IgG fraction of an anti-pyrene antiserum by the sol-gel method and evaluates the performance of the immunoaffinity columns prepared with respect to column stability, capacity, selectivity and non-specific binding on the glass matrix. The immunoaffinity columns prepared had a pyrene-breakthrough capacity of 78 ng g?1 gel and 38 ng mg?1 IgG. Pyrene could

M. Cichna; D. Knopp; R. Niessner

1997-01-01

379

Effects of sugar on the sol-gel transition in gellan gum aqueous solutions  

Microsoft Academic Search

The effects of glucose, fructose, sucrose and trehalose on the sol-gel transition in gellan gum aqueous solutions have been\\u000a studied using rheological measurements and differential scanning calorimetry (DSC). Thermal scanning rheological results suggested\\u000a that a 1 % gellan gum solution without sugar could not form a gel even on cooling to 0 °C; however, on addition of any sugar\\u000a at

E. Miyoshi; K. Nishinari

380

Electrical properties of high temperature insulation coatings by the sol-gel method for magnet technology  

Microsoft Academic Search

The electrical properties of high temperature insulation coatings, which were applied by sol-gel process on Ag or AgMg sheathed Bi-2212 tapes, bronze processed Nb3Sn wires and Ni tapes, have been studied by resistive, capacitance, and high voltage breakdown techniques. The electrical properties of the coatings with varying composition, coating type, number of dippings, and temperature and time of annealing process

E. Celik; I. H. Mutlu; Y. S. Hascicek

2000-01-01

381

Characterization and tribological investigation of sol–gel ceramic films on Ti–6Al–4V  

Microsoft Academic Search

SiO2, TiO2, and hydroxyapatite (HA) thin films with good biocompatibility were grown on Ti–6Al–4V (coded as TC4) substrate by sol–gel and dip-coating processes from specially formulated sols, followed by annealing at 500°C The chemical states of some typical elements in the target films were detected by means of X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) and high-resolution scanning electron

Wenguang Zhang; Chengtao Wang; Weimin Liu

2006-01-01

382

Some properties of protective sol–gel glass coatings on sintered stainless steels  

Microsoft Academic Search

Sol–gel SiO2 films are deposited onto sintered AISI 316 steel by dip-coating technique from TEOS (tetraethyl orthosilicate) precursor solution. Two different heating rates in the sintering step (800°C\\/2 h) were used, viz., 10 and 3°C\\/min. Analysis of the coatings were carried out by scanning electron microscopy and atomic force microscopy to determine the topographical features and the homogeneity of the

Mauricio Simões; Od??lio B. G Assis; Luis A Avaca

2000-01-01

383

Investigation of CO 2 sensor based on NASICON synthesized by a new sol–gel process  

Microsoft Academic Search

A small volume tube-type CO2 sensor was fabricated, which was based on the solid electrolyte material of NASICON prepared by using inorganic salt as raw material. As a sol–gel process was employed, the synthesizing temperature and time were reduced to 800°C and 8h, respectively. The resulted NASICON was characterized by XRD, IR, TEM and ion conductivity measurement. Within a wide

Fabin Qiu; Qifeng Zhu; Xiaotian Yang; Yujun Quan; Liangyan Sun

2003-01-01

384

Preparation and tribological properties of sol-gel zirconia thin films stabilized with ceria  

Microsoft Academic Search

High oriented ceria-stabilized zirconia (CSZ) thin films were prepared by the sol-gel method using zirconium oxychloride octahydrate and cerium chloride hexahydrate as starting materials. The morphology and microstructure of the films were investigated via X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films contained only tetragonal phase and showed nanoscale uniformity.

Yunxia Chen; Weimin Liu

2002-01-01

385

Synthesis and cryogenic properties of polyimide–silica hybrid films by sol–gel process  

Microsoft Academic Search

Polyimide–silica hybrid films were prepared from tetraethoxysilane (TEOS) and polyamic acid (PAA) via sol–gel process in the solution of N,N-dimethylacetamide (DMAc). The cryogenic mechanical and electrical properties of polyimide–silica hybrid films were studied taking into account the effects of silica content. The results indicated that the cryogenic modulus increased with the increase of silica content while the tensile strength and

Yi-He Zhang; Yan Li; Shao-Yun Fu; John H. Xin; Walid A. Daoud; Lai-Feng Li

2005-01-01

386

Li+ ions diffusion into sol-gel V2O5 thin films: electrochromic properties  

Microsoft Academic Search

V{2}O{5} thin films were prepared by the sol-gel spin coating process. The Li+ ions insertion effect on optical and electrochromic properties of those films was studied. The diffusion coefficient was calculated using both cyclic voltammograms and chronoamperometric curves. The amount x of Li+ ions in LixV{2}O{5} was also calculated. Finally, the electrochromic performance evolution characteristics such as the reversibility, coloration

M. Benmoussa; A. Outzourhit; A. Bennouna; A. Ihlal

2009-01-01

387

Sol-Gel Coatings on 316L Steel for Clinical Applications  

Microsoft Academic Search

SiO2 and SiO2-CaO-P2O5 coatings have been prepared by dipping electropolished stainless steel 316L samples and microscope glass slides in three different sol-gel solutions. Multilayered dense SiO2 coatings, and thick silica films obtained from equimolar contents of TEOS and MTES were used. The latter were able to strongly reduce both the corrosion attack on the steel and the iron diffusion to

Pablo Galliano; Juan José De Damborenea; M Jesús Pascual; Alicia Durán

1998-01-01

388

Osteoblast adhesion and matrix mineralization on sol–gel-derived titanium oxide  

Microsoft Academic Search

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

Maria C. Advincula; Firoz G. Rahemtulla; Rigoberto C. Advincula; Earl T. Adae; Jack E. Lemons; Susan L. Bellis

2006-01-01

389

Substrate dependence of preferred orientation in sol–gel-derived zinc oxide films  

Microsoft Academic Search

The preferred orientation of ZnO films synthesized by the sol–gel technique was investigated with increasing annealing temperature. Different substrates like soda-lime glass, quartz glass, Corning 7059 glass, polycrystalline Al2O3 and p-type Si(100) were used to examine the substrate effects on the growth of ZnO. The degree of orientation of the (002) plane in the films increased with temperature when the

S. Chakrabarti; D. Ganguli; S. Chaudhuri

2004-01-01

390

Encapsulation of Proteins in Transparent Porous Silicate Glasses Prepared by the Sol-Gel Method  

Microsoft Academic Search

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

Lisa M. Ellerby; Clinton R. Nishida; Fumito Nishida; Stacey A. Yamanaka; Bruce Dunn; Joan Selverstone Valentine; Jeffrey I. Zink

1992-01-01

391

Hydroxyapatite\\/titania composite bioactivity coating processed by sol–gel method  

Microsoft Academic Search

Hydroxyapatite\\/titania composite material was coated onto a titanium (pure Ti) substrate by sol–gel method. The hydroxyapatite (HA) and titania (TiO2) sol were made from precursor and mixed together. The insertion of TiO2 enhanced the chemical affinity and the physical consistency between HA and Ti substrate. The HA\\/TiO2 composite coating adhered tightly to the Ti substrate. Owing to the insertion of

J. Y. Han; Z. T. Yu; L. Zhou

2008-01-01

392

Fabrication of La2Ti2O7 thin films by a sol-gel technique  

Microsoft Academic Search

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

A. V. Prasadarao; U. Selvaraj; S. Komarneni; A. S. Bhalla

1992-01-01

393

Sol-gel processing of oriented SrTiO 3 thin films  

Microsoft Academic Search

Sol-gel processing was employed to fabricate multilayered SrTiO3 thin films onto fused silica, Si (100) and SrTiO3 (110) substrates. A Sr-Ti alkoxide precursor solution, chemically modified with diisopropanolamine, was hydrolyzed and spin-coated onto these substrates. These films were annealed at 300 °C and then heated to 650 °C for 1 h in air, which resulted in the formation of phase

Ulagaraj Selvaraj; Alamanda V. Prasadarao; Sridhar Komarneni; Rustum Roy

1995-01-01

394

Dye-sensitized solar cell based on blood mimetic thixotropy sol-gel electrolyte.  

PubMed

Blood mimetic thixotropy sol-gel electrolytes were prepared and sandwiched between dye-coated porous TiO(2) and a platinum counter-electrode to form a dye-sensitized solar cell. The highest overall conversion efficiency of 6.45%, and the fill factor of 0.74 under the white light irradiation AM 1.5 (100 mW cm(-2)) were obtained. PMID:21109861

Jin, Liguo; Wu, Ze; Wei, Tianxin; Zhai, Jin; Zhang, Xianyou

2010-11-25

395

Correlation of materials and ferroelectric properties of sputtered and sol-gel PZT films  

Microsoft Academic Search

The processes for the physical vapor deposition (PVD) of Pb(Zr,Ti)O3 (PZT) thin films from two different composite oxide targets has been demonstrated. PZT thin films have been deposited by both PVD or sputter technique and standard sol-gel method. Half micron PZT films were deposited by both methods on identical substrates (Si[(100) 4 inch Cz wafer]\\/SiO2\\/Ti-TiO2\\/Pt) followed by sputter-deposited Pt top

R. X. Fu; R. Mamazza; T. S. Zheleva; K. W. Kirchner; B. H. Piekarski

2009-01-01

396

Nanostructural control of the release of macromolecules from silica sol-gels.  

PubMed

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 70kDa is determined. Dextran, a hydrophilic polysaccharide, was selected as a large model molecule at molecular sizes of 10, 40 and 70kDa, 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 3.5nm. 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 3.5nm, thereby facilitating molecular out-diffusion. PMID:23643607

Radin, Shula; Bhattacharyya, Sanjib; Ducheyne, Paul

2013-05-02

397

Titania Thin Films and Supported Nanostructured Membranes Prepared by the Surfactant Assisted Sol-Gel Method  

Microsoft Academic Search

Thin TiO2 nanoparticulate layers were produced by a dip coating of quartz, bo- ron-silicate wafers and of plastic foils. The coating solution was prepared by the sol-gel method in the reverse micelle environment to favour the polycondensation. Reverse mi- celles of a non-ionic surfactant Triton X-100 in cyclohexane were used as the template. The molar ratio water\\/surfactant was kept low

P. Kluson; P. Kacera; T. Cajthaml; M. Kalajic

398

Sol–gel preparation of titania multilayer membrane for photocatalytic applications  

Microsoft Academic Search

The main goal of the present study is to prepare a titania membrane with high permeability and photocatalytic activity for environmental applications. In this investigation a mesoporous titania multilayer membrane on alumina substrate is successfully fabricated via the sol–gel processing method. The prepared titania polymeric sol for the membrane top layer has an average particle size of 11.7nm with a

Ali Alem; Hossein Sarpoolaky; Mehrdad Keshmiri

2009-01-01

399

Synthesis of nanocomposite powders of ?-alumina-carbon nanotube by sol–gel method  

Microsoft Academic Search

The nanocomposite powders of ?-alumina-carbon nanotube were successfully synthesized by a sol–gel process. The homogeneous mixture of carbon nanotubes and alumina particles was obtained by mixing the carbon nanotubes within alumina solution and followed by heating into gel. The resultant gel was dried and calcined at 200°C into boehmite-carbon nanotubes composite powders. The mean particle size of synthesized boehmite was

H. Barzegar-Bafrooei; T. Ebadzadeh

2011-01-01

400

On the surface basic properties of sulfated magnesia–silica sol–gel mixed oxides  

Microsoft Academic Search

The morphology and surface base properties of a family of sulfated MgO–SiO2 mixed oxides prepared by the sol–gel method were studied. Morphological features of the sulfated system are found to vary with preparative conditions. Electron dispersive spectroscopy (EDS) analysis of the samples show a very high homogeneous distribution of sulfur and magnesium on the surface. It was found by CO2-Thermal

T López; R Gómez; M. E Llanos; E Garc??a-Figueroa; J Navarrete; E López-Salinas

1999-01-01

401

Effect of sulfation on the photoactivity of TiO 2 sol–gel derived catalysts  

Microsoft Academic Search

Titania and sulfated-titania were prepared by the sol–gel method using titanium alkoxide as titania precursor. BET specific surface areas on samples calcined at 600°C were 57 and 62m2\\/g for titania and sulfated-titania, respectively. FTIR spectra of sulfated samples show the 1360–1370cm?1 absorption band assigned to S?O vibrations. Moreover, by means of FTIR-pyridine absorption the strength of the sulfate bonded on

R Gómez; T López; E Ortiz-Islas; J Navarrete; E Sánchez; F Tzompanztzi; X Bokhimi

2003-01-01

402

Wet sol–gel silica matrices as delivery devices for phenytoin  

Microsoft Academic Search

Wet sol–gel silica matrices produced under different hydrolysis conditions were used as delivery devices to the active principle\\u000a of an antiepileptic drug (phenytoin sodium), encapsulated during the condensation stage. Post-incorporation into dry silica\\u000a powder was an alternative loading procedure. It was proven by infrared spectroscopy that neither the silica network nor the\\u000a drug loose integrity by encapsulation. The kinetics of

Alexandra Fidalgo; Tessy M. Lopez; Laura M. Ilharco

2009-01-01

403

Acetone gas phase condensation on alkaline metals doped TiO 2 sol–gel catalysts  

Microsoft Academic Search

The vapor-phase condensation of acetone was studied over sol–gel prepared TiO2 and TiO2-doped with 1wt.% of Li+ or Rb+. The acetone condensation was catalyzed by basic sites and the obtained products were mesityl oxide (MO), isomesityl oxide (ISMO), mesitylene (M) as well as isophorone (IP) and phorone (P). The TiO2 crystalline structure was characterized by XRD and the basicity of

Marcial Zamora; Tessy López; Ricardo Gómez; Maximiliano Asomoza; Ruth Meléndrez

2005-01-01

404

Pt-Sn\\/Al 2 O 3 sol-gel catalysts: Metallic phase characterization  

Microsoft Academic Search

Highly dispersed platinum was found in Pt-Sn\\/Al2O3 catalysts prepared by the sol-gel method, i.e., cogelation of aluminum tri-sec-butoxide and tetrabutyltin and subsequent impregnation with hexachloroplatinic acid. X-ray diffraction studies showed that the cell parameter of pure platinum is not modified in bimetallic Pt-Sn samples. Moreover, energy dispersive X-ray analysis studies (EDX) showed that platinum, but not tin, was detected in

R. Gomez; V. Bertin; P. Bosch; T. Lopez; P. Angel; I. Schifter

1993-01-01

405

Tetragonal Nanophase Stabilization in Nondoped Sol–Gel Zirconia Prepared with Different Hydrolysis Catalysts  

Microsoft Academic Search

Sol–gel zirconia was prepared with zirconiumn-butoxide and HCl, H2SO4, C2H4O2, and NH4OH as hydrolysis catalysts. Samples were characterized with DTA and TG analysis, X-ray powder diffraction, and FTIR spectroscopy. The structure of the crystalline phases was refined by the Rietveld method. When samples were annealed below 300°C, they lost weight and had an amorphous structure that, by annealing at higher

X. Bokhimi; A. Morales; O. Novaro; M. Portilla; T. López; F. Tzompantzi; R. Gómez

1998-01-01

406

Synthesis of Ba 3Li 2Ti 8O 20 sol–gel at basic conditions  

Microsoft Academic Search

The compound Ba3Li2Ti8O20 was synthesized by the sol–gel method in the presence of ammonium hydroxide as hydrolysis catalyst. The precursors used were titanium isopropoxide, barium sopropoxide and lithium acetate salt. Portions of the gel obtained were annealed at different temperatures. The samples were characterized by IR spectroscopy, X-ray diffraction and thermal analysis. The hydrolysis process depends on the pH. The

Aracely Hernandez; Leticia M. Torres-Martinez; Tessy Lopez

2002-01-01

407

Synthesis and Characterization of Sol–Gel Pt\\/TiO 2Catalyst  

Microsoft Academic Search

Pt\\/TiO2catalysts with 1.0 wt% Pt were prepared by using the sol–gel technique with Ti(OBut)4and platinum acetylacetonate. The catalysts were prepared in only one step, without the need to reduce the sample in hydrogen. All fresh samples have three nanophases: rutile (the majority phase), anatase, and platinum. Their crystalline structure was obtained by X-ray powder diffraction and refined with the Rietveld

E. Sanchez; T. López; R. Gómez; Bokhimi; A. Morales; O. Novaro

1996-01-01

408

Sol–gel iron complex catalysts supported on TiO 2 for ethylene polymerization  

Microsoft Academic Search

The Fe((SO4)2(NH4)2)\\/TiO2 compound was prepared via the sol–gel technique at pH 9 dried at 70°C and treated thermally at different calcination temperatures (200, 400, 600 and 800°C). It was characterized by BET, XPS and XRD and it was tested as a catalyst for ethylene polymerization. A strong dependence was found between the structural properties of the support, the iron complex

Ana Mar??a Dom??nguez; Antonio Zárate; Raúl Quijada; Tessy López

2004-01-01

409

Evolution of two acid steps sol–gel phases by FTIR  

Microsoft Academic Search

FTIR has been used to follow the evolution of a sol–gel preparation accomplished with two acid\\/acid steps. The reaction of\\u000a methyltrimethoxysilane mixed with colloidal silica was taken as an example, aiming at proving the use of IR spectroscopy for\\u000a the determination of reaction aspects like the kinetic behaviour that is essential for the scale-up of the application. The\\u000a steps were

S. Amoriello; A. Bianco; L. Eusebio; P. Gronchi

2011-01-01

410

Zinc selenide (ZnSe) nanoparticles prepared by sol-gel method  

Microsoft Academic Search

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

Sabar D. Hutagalung; Siaw C. Loo

2007-01-01

411

Synthesis and characterization of silica xerogels obtained via fast sol–gel process  

Microsoft Academic Search

The synthesis and physical properties of high surface area silica xerogels obtained by a two-step sol–gel process in the absence\\u000a of supercritical conditions are reported. The hydrolysis and condensation reactions were followed by infrared spectroscopy.\\u000a The increment in the bands corresponding to silanol and hydroxyl groups suggests that the hydrolysis reaction was complete\\u000a during the first 30 min. The effect on

Guillermo Andrade-Espinosa; Vladimir Escobar-Barrios; Rene Rangel-Mendez

2010-01-01

412

Non-fluorinated superamphiphobic surfaces through sol–gel processing of methyltriethoxysilane and tetraethoxysilane  

Microsoft Academic Search

In this study, a simple approach was developed to fabricate an extremely superamphiphobic coating material by the tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) sol–gel derived materials. TEOS and MTES derived moieties were designed for a physical roughness and hydrophobic surface characteristic, respectively. The 29Si solid-state NMR and ESCA analysis showed the coated silica composition was similar to the feeding ratios of

Yuung-Ching Sheen; Wei-Hsuan Chang; Wen-Chang Chen; Yih-Her Chang; Yuan-Chang Huang; Feng-Chih Chang

2009-01-01

413

Preparation and properties of electrochromic iridium oxide thin film by sol-gel process  

Microsoft Academic Search

We established a method for preparation of iridium oxide thin film by the sol-gel dip-coating process where iridium chloride was used as a starting material. The coating solution was prepared by reacting iridium chloride, ethanol and acetic acid. Iridium oxide coating was formed at 2.0 cm\\/min withdrawing rate. The coating films heat treated at 300°C did not contain impurities. Iridium

K. Nishio; Y. Watanabe; T. Tsuchiya

1999-01-01

414

Development and thermal evolution of silver clusters in hybrid organic–inorganic sol–gel coatings  

Microsoft Academic Search

A silver doped hybrid organic–inorganic sol–gel coating was developed through the hydrolytic condensation of tetraethoxysilane (TEOS) and methyl-triethoxysilane (MTES). Silica nanoparticles were added in order to give a mechanical reinforcement and silver nitrate as the supplier of Ag+ ions, which have a potential effect as a biocide component. Synthesis of precursor sol and the evolution of silver clusters in the

R. Procaccini; S. Ceré; S. Pellice

2011-01-01

415

Hydroxyapatite coating on Ti6Al4V alloy using a sol–gel derived precursor  

Microsoft Academic Search

A simple rapid-heating method was successfully developed for calcium phosphate coatings on Ti6Al4V substrates deposited by using a sol–gel derived precursor. After five repetitions of coating procedures and heat treatment at 600°C, the formation of hydroxyapatite (HA) has been confirmed by X-ray diffractometry (XRD) analyses and the substrate material was found to be slightly oxidized. The residual organics, as revealed

Ming-Fa Hsieh; Li-Hsiang Perng; Tsung-Shune Chin

2002-01-01

416

Application of ultrasonic irradiation to the sol–gel synthesis of silver vanadium oxides  

Microsoft Academic Search

An ultrasonic irradiation method was applied to the sol–gel synthesis of silver vanadium oxides (SVO). Transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA) were conducted to research the ultrasonically accelerated reaction between V2O5 gel and Ag2O powder. Galvanostatic discharge experiments showed that the as prepared cathode active material of Ag2V4O11 and Ag1.2V3O8 have better

Jinggang Xie; Xiaoyu Cao; Jinxia Li; Hui Zhan; Yongyao Xia; Yunhong Zhou

2005-01-01

417

Electrical switching in sol-gel-derived SiO2 films  

Microsoft Academic Search

We have investigated electrical switching behavior of sol-gel derived SiO2 films in c-Si(p)\\/SiO2\\/metal structures. The SiO2 film is fabricated from silicafilm (a soluble Si polymer in dissolved in denatured alcohol) using spin-coating technique. The thickness of the film is in the range of 300~2000 Å which depends on both spinning speed and the degree of dilution. We find that, with

Jian Hu; Scott Ward; Qi Wang

2003-01-01

418

Sol-Gel derived PbTiO3 films on a polar glass ceramic substrate  

Microsoft Academic Search

Sol-Gel derived PbTiO3 films were prepared with a polar glass ceramic as the substrate. The crystallization was investigated by means of X-ray diffraction. A preferential c-axis orientation in the film was observed. The grain size and the microstrain were determined by measuring the integrated width of the diffraction. The grain size increases with increasing firing temperature following an Arrhenius relation.

P. L. Zhang; W. L. Zhong; S. L. Wang; Y. G. Wang; Z. Y. Ding

1994-01-01

419

Abrasion resistant inorganic\\/organic coating materials prepared by the sol-gel method  

Microsoft Academic Search

Novel abrasion resistant coating materials prepared by the sol-gel method have been developed and applied on the polymeric substrates bisphenol-A polycarbonate and diallyl diglycol carbonate resin (CR-39). These coatings are inorganic\\/organic hybrid network materials synthesized from 3-isocyanatopropyltriethoxysilane functionalized organics and metal alkoxide. The organic components are 3,3'-iminobispropylamine (IMPA), resorcinol (RSOL), diethylenetriamine (DETA), poly(ethyleneimine) (PEI), glycerol and a series of diols.

J. Wen; V. J. Vasudevan; G. L. Wilkes

1995-01-01

420

An evaluation of the dyeing behavior of sol–gel silica doped with direct dyes  

Microsoft Academic Search

A new dyeing process of sol–gel silica doped with direct dyes is investigated for improving color strength (K\\/S value) and dyeing fastness. Cotton fabrics are dyed in this direct dye silica solution. The results indicate that the K\\/S value of C.I. Direct Blue 86 and C.I. Direct Red 23 are enhanced by 12.8% and 16.8%, respectively. For C.I. Direct Blue

Yunjie Yin; Chaoxia Wang; Chunying Wang

2008-01-01

421

Hydroxyapatite coating on titanium substrate with titania buffer layer processed by sol–gel method  

Microsoft Academic Search

Hydroxyapatite (HA) was coated onto a titanium (Ti) substrate with the insertion of a titania (TiO2) buffer layer by the sol–gel method. The HA layer was employed to enhance the bioactivity and osteoconductivity of the Ti substrate, and the TiO2 buffer layer was inserted to improve the bonding strength between the HA layer and Ti substrate, as well as to

Hae-Won Kim; Young-Hag Koh; Long-Hao Li; Sook Lee; Hyoun-Ee Kim

2004-01-01

422

Ceramic thin films by sol-gel processing as novel materials for integrated humidity sensors  

Microsoft Academic Search

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

Enrico Traversa; Guglielmina Gnappi; Angelo Montenero; Gualtiero Gusmano

1996-01-01

423

A visible-light response vanadium-doped titania nanocatalyst by sol–gel method  

Microsoft Academic Search

A series of vanadium-doped TiO2 catalysts were synthesized by two modified sol–gel methods. V-doped TiO2 was found to be mainly preserved its anatase phase after calcination at 400°C. The TEM micrographs showed the sizes of primary particles were in the range of 6–20nm. The increase of vanadium doping promoted the particle growth, and enhanced “red-shift” in the UV-Vis absorption spectra.

Jeffrey C.-S Wu; Chih-Hsien Chen

2004-01-01

424

Superhydrophobic cotton fabrics prepared by one-step water-based sol–gel coating  

Microsoft Academic Search

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,

Lihui Xu; Wei Zhuang; Bi Xu; Zaisheng Cai

2012-01-01

425

Superhydrophobic cotton fabrics prepared by one-step water-based sol–gel coating  

Microsoft Academic Search

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,

Lihui Xu; Wei Zhuang; Bi Xu; Zaisheng Cai

2011-01-01

426

Sol-gel deposition of nanostructured low refractive index materials on solar collector glazing  

Microsoft Academic Search

Nanoporous SiO2 and nanocomposite MgF2:SiO2 coatings have been deposited by sol-gel dip- coating in a particle-free atmosphere. The refractive index of the prepared nanostructured thin films is determined from spectrophotometric data. In both cases, significantly lower values than for compact SiO2 have been achieved. Highly transparent samples have been produced in a single dip-coating step followed by simple thermal annealing

A. Schüler; D. Dutta; H. Chelawat; E. De Chambrier; C. Roecker; J.-L. Scartezzini

427

Sol-gel preparation and phosphorescence property of Mn 2+ -doped zinc borosilicate glass thin films  

Microsoft Academic Search

Mn2+-doped zinc borosilicate (ZBSM) glass thin films were first synthesized by sol-gel method. In the experiment, a thin gel film\\u000a was deposited onto quartz glass substrates by dip-coating method and then heat-treated to form a Mn2+-doped zinc borosilicate glass thin film. Long lasting phosphorescence (LLP) and photo-stimulated long lasting phosphorescence\\u000a (PSLLP) were found in the film sample. According to fluorescence

Fengfeng Li; Mingxi Zhang; Guiqin Hou; Yi Shen; Zhigang Liu; Hongsheng Li

2011-01-01

428

Coloration mechanisms of sol–gel NiO–TiO 2 layers studied by EQCM  

Microsoft Academic Search

An electrochemical quartz crystal microbalance was used as a sensitive detector to analyse the mass changes occurring during the coloration\\/bleaching processes of sol–gel NiO–TiO2 electrochromic layers. Double layers were deposited on gold-coated quartz crystal electrode and sintered at 300°C in air. The electrochemical process was studied in KOH electrolyte in the potential range ?0.4 to +0.57V vs. SCE during 650

A. Al-Kahlout; M. A. Aegerter

2007-01-01

429

Sol–gel derived ZnO\\/PVP nanocomposite thin film for superoxide radical sensor  

Microsoft Academic Search

Pure ZnO films and ZnO nanoparticle-dispersed polyvinylpyrrolidone (PVP) composite films are prepared on Pyrex glass substrates by the sol–gel dip-coating technique utilizing zinc acetate precursor. The thin films are extensively characterized for surface morphology, chemistry, and nanocrystallite size using various advanced analytical techniques including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For the

Tianbao Du; Hongwei Song; Olusegun J. Ilegbusi

2007-01-01

430

Physical Properties of Potassium Phosphate Glass Prepared by Sol Gel Method  

Microsoft Academic Search

Series of glasses based on Al2O3-K2O-P2O5 have successfully been made by sol gel method. The amorphous state has been confirmed by X-ray diffraction (XRD) while the actual composition has been determined using Energy Dispersive X-ray (EDX) analysis. The glass density is determined using Archimedes method while the Vickers Micro hardness Test has been used to measure the hardness. It is

Noorhidayah Che Mat; Safwan Ahmad Pauzi

2010-01-01

431

Synthesis and Characterization of LiMVO4 Cathode Material Produced by Sol-gel Method  

NASA Astrophysics Data System (ADS)

Lithium manganese vanadate (LiMnVO4) has been prepared by a sol-gel method. XRD analysis reveals that the prepared sample possess orthorhombic structure. Laser Raman spectrum shows the local environment of cations vibrational modes with respect to neighboring oxygen atom. The ionic conductivity of the sample is found to be 8.5×10-5 S cm-1 at 350 °C.

Prakash, D.; Jayachandran, M.; Sanjeeviraja, C.

2011-07-01

432

Preparation of titanium(IV) oxide thin film photocatalyst by sol–gel dip coating  

Microsoft Academic Search

Thin films of titanium dioxide (TiO2) were deposited on variety of substrates by a simple sol–gel dip coating technique. The substrates were coated with titanium peroxide precursor solution of controlled viscosity at a constant pulling rate of 1mms?1, air-dried and further heated at 400°C to obtain uniform films with good adhesion to the substrate. The change in viscosity of the

R. S Sonawane; S. G Hegde; M. K Dongare

2003-01-01

433

Development of acetylcholinesterase silica sol–gel immobilized biosensor—an application towards oxydemeton methyl detection  

Microsoft Academic Search

An amperometric silica sol–gel film immobilized biosensor doped with acetylcholinesterase was fabricated in the laboratory finding application in organophosphate detection based on enzyme inhibition. The substrate used was acetylthiocholine chloride and thiocholine released from the enzymatic hydrolysis was electrochemically oxidized giving larger anodic current at 0.5–0.6V (versus Ag\\/AgCl reference). The dependencies of the current response on pH, enzyme loading and

K. Anitha; S. Venkata Mohan; S. Jayarama Reddy

2004-01-01

434

Photochromic coatings including silver halide microcrystals via sol–gel process  

Microsoft Academic Search

Photochromic coatings including silver halide microcrystals were formed on a glass substrate via the sol–gel process. 3-Glycidoxypropyltrimethoxysilane and methyltrimethoxysilane were used as starting materials of the ormosil matrices. The 3-chloropropyltrimethoxysilane and bromophenyltrimethoxysilane were added as halogen sources and silver colloidal dispersions were introduced into the precursor solution. The precursor solution was applied using a spin-coating process on a silica buffer

Hiroyuki Tomonaga; Takeshi Morimoto

2001-01-01

435

Effect of rigid inclusions on the sintering of mullite synthesized by sol-gel processing  

Microsoft Academic Search

The effect of crystalline particulate inclusions of mullite or zirconia on the sintering and crystallization of a mullite powder matrix was investigated as a function of the inclusion volume fraction and size. The mullite powder was synthesized by sol-gel processing and, within the limits of X-ray diffraction, was amorphous. Composites containing up to 22.5 vol % zirconia reached almost full

D.-Y. Jeng; M. N. Rahaman

1993-01-01

436

Synthesis and Characterization of Optical Sol–Gel Adhesive for Military Protective Polycarbonate Resin  

Microsoft Academic Search

Sol–gel adhesive material for isostatic hotpressing lamination process was synthesized using 3-aminopropyltrimethoxysilane (APTES), 3-glycidyloxypropyltrimethoxysilane (GPTS) and methacryloxypropyltrimethoxysilane (MPTS) as precursors. Reaction dynamics between APTES and GPTS was followed on-line with Raman spectroscopy. The lamination process was optimized by varying hotpressing times and pressures at the constant temperature. Mechanical shear strength properties were found to be excellent for studied composition, 25–30

Mikko Keränen; Marcin Gnyba; Paavo Raerinne; Terho Kololuoma; Arto Maaninen; Juha T. Rantala

2004-01-01

437

Sol\\/gel phase diagrams of industrial organo-bentones in organic media  

Microsoft Academic Search

The gelation process of industrial organo-bentone in organic solvents is a complex phenomenon due to various parameters, such as, the crystallographic nature of the clay, the nature of adsorbed surfactant, the dielectric constant of medium. Sol-gel phase diagrams have been established by varying the dielectric constant versus solid-liquid ratio of the mixture (mass percentage). To modify the dielectric constant, different

B. Gherardi; A. Tahani; P. Levitz; F. Bergaya

1996-01-01

438

Structure and biological response of polymer\\/silica nanocomposites prepared by sol–gel technique  

Microsoft Academic Search

Structure of P(EMA-co-HEA)\\/SiO2 nanocomposites with silica content in the range from 0 to 30wt.% was correlated with cell behavior on substrates of those compositions by making use of two different populations of primary human cells: articular cartilage chondrocytes and dental pulp cells. Substrates were prepared by the simultaneous copolymerization of the organic monomers and the sol–gel reaction of the silica

A. Vallés-Lluch; E. Costa; G. Gallego Ferrer; M. Monleón Pradas; M. Salmerón-Sánchez

2010-01-01

439

Sol–gel coatings for corrosion protection of 1050 aluminium alloy  

Microsoft Academic Search

The formation of organic-modified sol–gel coatings on 1050 aluminium alloy has been examined. The coatings were prepared by the combination of a completely hydrolysable precursor of tetra-n-propoxyzirconium (TPOZ), with a partly hydrolysable precursor of glycidoxypropyltrimethoxysilane (GPTMS). Influences of GPTMS\\/TPOZ ratio, withdrawal speed and curing temperature on the barrier-type corrosion protection of the alloy were examined. By control of process parameters

Z. Feng; Y. Liu; G. E. Thompson; P. Skeldon

2010-01-01

440

Preparation of mesoporous silica thin films on polystyrene substrate by electrochemically induced sol–gel technique  

Microsoft Academic Search

The mesoporous silica thin films with an oriented hexagonal mesostructure were prepared on polystyrene (PS) substrate by electrochemically induced sol–gel technique using tetraethoxyorthosilicate (TEOS) as silica source and cetyltrimethyl-ammonium bromide (CTAB) as structure-directing agent. Prior to coating deposition, the PS substrate was made hydrophilic by sulfonation with concentrated sulfuric acid for 72h to provide better adhesion of silica films to

Xiaona Wang; Rongchun Xiong; Gang Wei

2010-01-01

441

Coating on Porous Si3N4 Based Substrate with Sol-Gel Slurry  

Microsoft Academic Search

The coating was prepared on porous Si3N4 based substrate by dip-coating from sol-gel slurry. The slurry was made by adding pretreated silicon into alumina sol. The coated substrate was heated at 1420°C in nitrogen atmosphere. The phase of dried powder from slurry was studied by X-ray diffraction. The surface morphology of coated substrate was determined by scanning electronic microscope. The

Chaochen Zhang; Xiaolei Li; Huiming Ji; Xiaohong Sun

2012-01-01

442

Use of sol-gel thin films in solar energy applications  

Microsoft Academic Search

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

R. B. Pettit; C. J. Brinker

1985-01-01

443

Photoluminescence properties of sol–gel derived SiO 2 layers doped with porous silicon  

Microsoft Academic Search

We proposed and studied a new light emitting material based on silicon nanocrystals (Si-nc). The new material was fabricated using a low cost way by incorporating Si-nc into a sol–gel derived SiO2 matrix. The Si-nc were prepared (i) by electrochemical etching of monocrystalline Si wafers and (ii) pulverizing the obtained porous silicon film. The porous silicon powder was then dispersed

V Švr?ek; I Pelant; J.-L Rehspringer; P Gilliot; D Ohlmann; O Crégut; B Hönerlage; T Chvojka; J Valenta; J Dian

2002-01-01

444

The nanocrystalline ceria sol-Gel coatings for high temperature applications  

Microsoft Academic Search

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

F. Czerwinski; J. A. Szpunar

1997-01-01

445

The Nanocrystalline Ceria Sol-Gel Coatings for High Temperature Applications  

Microsoft Academic Search

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

F. Czerwinski; J. A. Szpunar

1997-01-01

446

Investigation of an automated cleaning system for LMJ coating sol-gel process  

Microsoft Academic Search

The French Commission for Atomic Energy is currently involved in a project which consists in the construction of a 2MJ\\/500TW (351nm) laser, so called LMJ (Megajoule-class laser) devoted to Inertial Confinement Fusion (ICF) research in France[1]. For this high power lasers, the sol-gel process[2] has been selected for 95% of laser optical coated area because of room temperature and atmospheric

E. Lavastre; S. Fontaine; R. Bergez; P. Wender; P. Cormont; C. Pellegrini; L. Beaurain; P. Belleville

2008-01-01

447

Optical sol-gel coating production for French high-power laser drivers  

Microsoft Academic Search

The French Commission for Atomic Energy is currently involved in a project which consists of the construction of a 2 MJ\\/500TW (351-nm) laser, so-called LMJ (Megajoule-class laser) devoted to Inertial Confinement Fusion (ICF) research in France. A prototype facility so-called LIL is used today to qualify the laser architecture. For these high power lasers the sol-gel process has been selected

Philippe Prené; Eric Lavastre; Philippe F. Belleville

2003-01-01

448

Diffusion and optical properties of Nd-doped sol-gel silica glasses  

Microsoft Academic Search

Water and acetone neodymium nitrate solutions of up to 2.3 mol\\/l were used to impregnate porous sol-gel glass by immersing outgassed samples in the liquid for a specified time. Diffusion coefficients of the solvents were determined using the diaphragm technique. Concentrations of the solute in the pores of samples having various average pore diameters were determined from the intensity of

Neil D. Koone; T. W. Zerda

1995-01-01

449

Template-based growth of TiO2 nanorods by sol-gel process  

Microsoft Academic Search

In this paper, the preparation of TiO2 nanorods by sol-gel-template process has been considered. The prepared sols were characterized by using FTIR spectroscopy, and the obtained nanorods were characterized by X-ray diffraction and SEM microscopy. SEM images show that TiO2 nanorods with uniform diameter of about 100-200 nm and a length of several micrometers. The results of XRD indicated that

A. Sadeghzadeh-Attar; M. Sasani Ghamsari; F. Hajiesmaeilbaigi

450

Sol–gel-derived corrosion-protective coatings with controllable release of incorporated organic corrosion inhibitors  

Microsoft Academic Search

Sol–gel derived organo-silicate hybrid coatings preloaded with organic corrosion inhibitors have been developed in order to provide active corrosion protection when integrity of the coating is compromised. The incorporation of organic corrosion inhibitors into hybrid coatings has been achieved as a result of physical entrapment of the inhibitor within the coating material at the stage of film formation and cross-linking.

A. N. Khramov; N. N. Voevodin; V. N. Balbyshev; R. A. Mantz

2005-01-01

451

Physical characteristics of heat-treated nano-silvers dispersed in sol gel silica matrix  

Microsoft Academic Search

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

A. Babapour; O. Akhavan; R. Azimirad; A. Z. Moshfegh

2006-01-01

452

Sol–gel-entrapped nano silver catalysts-correlation between active silver species and catalytic behavior  

Microsoft Academic Search

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

Vasile I. Pârvulescu; Bogdan Cojocaru; Viorica Pârvulescu; Ryan Richards; Zhi Li; Chris Cadigan; Pascal Granger; Pierre Miquel; Chris Hardacre

2010-01-01

453

pH optical sensors based on sol–gels: Chemical doping versus covalent immobilization  

Microsoft Academic Search

pH sensitive fluorescent sol–gels were obtained by both covalent immobilization of aminofluorescein (AF) via isocyanate or epoxy groups, and by co-condensation of tetramethoxysilane (TMOS) and phenyltrimethoxysilane (Ph-TriMOS) in the presence of AF. The gel precursors were deposited on glass supports, cured, and characterized in terms of response to pH, pKa values, effects of ionic strength, response time, leaching, long-term stability,

Aleksandra Lobnik; Ines Oehme; Ivana Murkovic; Otto S Wolfbeis

1998-01-01

454

Long-term renewable sol-gel fluorescent optical fiber pH sensor  

Microsoft Academic Search

The construction and the operation properties of an organically doped, sol-gel cladded optical fiber pH sensor, are described. The silica-entrapped indicator in the fluorescence-based device was fluorescein, pumped with a continuous wave (cw) argon 488 nm laser. The transmitted signal through the sensing fiber yielded a response in the pH range of 4 - 7, where signal level increased from

Oded Ben-David; Ehud Shafir; Irith Gilath; Yehiam Prior; David Avnir

1997-01-01

455

Leaching in sol–gel-derived silica films for optical pH sensing  

Microsoft Academic Search

The effect of different processing parameters on the efficiency of entrapment of pH indicators in a sol–gel-derived silica film is reported. An evanescent wave absorption approach was used to monitor dopant-leaching from these films. The issues investigated include the effect on the rate of leaching of the water:alkoxide ratio, the pH of the leachant solution and the choice of silicon

T. M. Butler; B. D. MacCraith; C. McDonagh

1998-01-01

456

A luminescence endotoxin biosensor prepared by the sol–gel method  

Microsoft Academic Search

Silicate thin films with terminal amino groups were prepared via the sol–gel technique and selected biological molecules labeled with luminophores were covalently attached to their surfaces. The obtained thin films with covalently bound Concanavalin-A (Con-A) labeled with fluorescein (FITC) were immersed in a buffer and polarized emission spectra were measured. In the next step, the samples were incubated with a

A. Hreniak; K. Maruszewski; J. Rybka; A. Gamian; J. Czyzewski

2004-01-01

457

CHARACTERIZATION OF CERIUM-DOPED YTTRIUM ALUMINIUM GARNET NANOPOWDERS SYNTHESIZED VIA SOL-GEL PROCESS  

Microsoft Academic Search

In this work the sol-gel process was used to prepare Ce-doped yttrium aluminium garnet (Y3Al5O12, YAG) samples. The synthesis products were characterized by infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD), and transmission electron microscopy (TEM). The particle size and luminescence properties of synthesized samples were also determined. The XRD patterns of Y3Al5O12:Ce samples showed that phase purity of garnets

A. Katelnikovas; T. Jüstel; D. Uhlich; J.-E. Jørgensen; S. Sakirzanovas; A. Kareiva

2008-01-01

458

Photoluminescence of ZnO quantum dots produced by a sol–gel process  

Microsoft Academic Search

We report synthesis and spectroscopic characterization of sol–gel derived zinc oxide (ZnO) quantum dots (Qdots) of 3–8nm size. The Qdots exhibited a broad and strong visible emission peak centered near 520nm with a quantum efficiency of approximately 5%. A weak ultraviolet (UV) emission peak was also observed near the band gap at 370nm. The integrated area under the curve for

Debasis Bera; Lei Qian; Subir Sabui; Swadeshmukul Santra; Paul H. Holloway

2008-01-01

459

Characterization of UV curable hybrid hard coating materials prepared by sol-gel method  

Microsoft Academic Search

Using sol-gel method, UV-curable urethane acrylate resin system was hybridized with inorganic silicate network to produce\\u000a hybrid coating materials with high anti-abrasive property. In preparation of acrylate\\/SiO2 hybrid materials, various acrylic reactants with multi-functional groups in addition to urethane acrylate oligomer as the\\u000a main network former were employed to obtain more densified organic network structure with a high degree of

Seong Woo Kim

2011-01-01

460

UV Curable Hard Transparent Hybrid Coating Materials on Polycarbonate Prepared by the Sol-Gel Method  

Microsoft Academic Search

UV curable, hard, transparent inorganic\\/organic composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. These hybrid coating materials were synthesized using a commercially available, acrylate end-capped polyester or polyurethane oligomeric resin (EBC80, EBC284), hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (TMSPM) as a coupling agent between the organic and inorganic phase, and

J. Gilberts; A. H. A. Tinnemans; M. P. Hogerheide; T. P. M. Koster

1998-01-01

461

Synthesis and characterization of sol–gel-derived molecular imprinted polymeric materials for cholesterol recognition  

Microsoft Academic Search

The sol–gel-derived host matrices are well known for biosensor applications where various types of organic and biological\\u000a molecules can be immobilized and can act as recognition elements. The molecular imprinting technology is an attractive alternative\\u000a method where expensive and labile biorecognition elements can be replaced by molecular imprinted polymers (MIPs), which are\\u000a capable of recognizing a target molecule of an

Radha Gupta; Ashok Kumar

2011-01-01

462

Investigations on the sol–gel-derived barium zirconium titanate thin films  

Microsoft Academic Search

Barium zirconium titanate thin films are attractive candidates for dynamic random access memories and tunable microwave devices. In the present work, a wide range of Zr-doped BaTiO3 thin films has been prepared by sol–gel technique. X-ray diffraction and micro-Raman scattering studies confirmed the structural phases in the powder and films of BZT and various structural transitions of BaTiO3, as a

A Dixit; S. B Majumder; A Savvinov; R. S Katiyar; R Guo; A. S Bhalla

2002-01-01

463

Sol-gel processing and properties of cerium doped Barium Strontium Titanate thin films  

Microsoft Academic Search

A stock solution sol-gel based method for making Barium Strontium Titanate (BST) thin films has been developed. A modified titanium alkoxide was combined with a barium and\\/or strontium inorganic salt in methoxyethanol and ethylene glycol to form the solution. The effect of chemistry on the stability of this BST solution is discussed. The crystallization temperature of 700–725°C for rapid thermally

M. Sedlar; M. Sayer; L. Weaver

1995-01-01

464

Resistive Switching Characteristics of Sol–Gel Zinc Oxide Films for Flexible Memory Applications  

Microsoft Academic Search

Unipolar resistive switching devices are investigated for nonvolatile memory applications in a metal-insulator-metal structure in which the insulator layer is based on sol-gel-derived zinc oxide (ZnO) films prepared by a simple spin-coating process followed by thermal annealing. Fast programming ( les 50 ns) and a high off-to-on resistance ratio ( ges 104) is demonstrated. The influences on the switching behaviors

Sungho Kim; Hanul Moon; Dipti Gupta; Seunghyup Yoo; Yang-Kyu Choi

2009-01-01

465

Air quality monitoring by means of sol–gel integrated tin oxide thin films  

Microsoft Academic Search

Sol–gel pure and Pd-doped SnO2 thin films on integrated substrates were developed to detect NO2 and CO. PdO particles are included in the film matrix and their presence enhances the CO gas sensitivity and response time. Measurements of electrical conductivity showed that these films have a response variation higher than 1000% for NO2 at temperatures in the range of about

R Rella; P Siciliano; S Capone; M Epifani; L Vasanelli; A Licciulli

1999-01-01

466

A simple sol–gel technique for preparing lanthanum oxide nanopowders  

Microsoft Academic Search

Nanosized lanthanum oxide powders have been prepared by a simple sol–gel technique using commercial lanthanum oxide, nitrate acid and polyethylene glycol (PEG) as the starting materials. The decomposition process of dried gel powders were investigated by differential thermal and thermogravimetric analysis(TG-DSC). The crystalline structures and morphologies of the powders were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM).

Xingang Wang; Maolin Wang; Hua Song; Bingjun Ding

2006-01-01

467

Reflow technique for the fabrication of an elliptical microlens array in sol-gel material  

Microsoft Academic Search

A simple reflow technique is employed for the fabrication of elliptical refractive microlens arrays (MLAs) on a low-cost inorganic-organic SiO2\\/ZrO2 sol-gel glass. The measured results show that the fabricated elliptical microlenses in a 256 × 512 array have excellent surface and dimensional qualities in terms of smoothness and uniformity. It is also shown that the optical parameters of the MLAs,

Miao He; Xiaocong Yuan; Nam Q. Ngo; Wai C. Cheong; Jing Bu

2003-01-01

468

Variable surface profile gratings in sol-gel glass fabricated by holographic interference  

NASA Astrophysics Data System (ADS)

Holographic interference is widely used for fabrication of sinusoidal gratings in photosensitive optical material. We present variable surface profile gratings fabricated in photosensitive hybrid sol-gel glass by use of holographic interference. It is found by experiment that different surface profiles of gratings including sinusoidal, binary, and two-peak sinusoidal can be obtained by precise control of exposure time. The experimental results are helpful for researchers fabricating gratings by holographic interference.

Yu, Weixing; Yuan, X.-C.

2003-08-01

469

Effect of Solvent Diols and Ligands on the Properties of Sol-Gel Alumina-Silicas  

Microsoft Academic Search

Amorphous alumina-silicas were prepared from a tetra-alkoxysilane and anhydrous aluminum trichloride or an aluminum alkoxide by a sol-gel process using 2-methyl-2,4-pentanediol, pinacol, 1,2-propanediol, 2,3-butanediol or ethylene glycol as the solvent or complexing agent, and the effect of diols and alkoxy groups on the physical and chemical properties of the alumina-silicas was examined. When the diol or the alkoxy group was

Fujio Mizukami; Yoshimichi Kiyozumi; Tsuneji Sano; Shu-ich Niwa; Makoto Toba; Shigemitsu Shin

1998-01-01

470

CO 2 capture using mesoporous alumina prepared by a sol–gel process  

Microsoft Academic Search

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

Chao Chen; Wha-Seung Ahn

2011-01-01

471

Synthesis and characterization of cadmium titanium oxide powders by sol-gel technique  

Microsoft Academic Search

Uniform crystals of CdTiO3 orthorhombic phase have been preapred by Sol-Gel method using titanium butoxide and cadmium acetate. For the first time the sample has been characterised detailedly to confirm the formation of pure single phase of CdTiO3. It is observed that the sample sintered at 500°C for 5 h showed complete formation of the single phase of CdTiO3 by

A. R. Phani; M. Passacantando; S. Santucci

2000-01-01

472

Non-aqueous primary cell  

NASA Astrophysics Data System (ADS)

This patent application relates to electrochemical cells and especially to high-energy, liquid cathode, non-aqueous lithium electrochemical cells free from highly toxic materials. A non-aqueous lithium electrochemical cell is described which includes a halocarbon cathode depolarizer which is 1,2-dichloroethane, 1.1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,2-dichloro-1,1-difluoroethane or mixtures thereof and a cathode catalyst which is copper, rhodium, palladium, cobalt phthalocyanine, nickel phthalocyanine, iron phthalocyanine, a cobalt tetraaza-(14)-annulene, a nickel tetraaza-(14)-annulene, a iron tetraaza-(14)-annulene, a cobalt porphyrin, a nickel porphyrin, a iron porphyrin, or a mixture thereof.

James, S. D.; Smith, P. H.; Oneill, K. M.; Wilson, M. H.

1986-05-01

473

Sol–gel based mid-infrared evanescent wave sensors for detection of organophosphate pesticides in aqueous solution  

Microsoft Academic Search

This work demonstrates the application of organically modified sol–gels as recognition layers combined with mid-infrared evanescent wave sensors for in situ detection of nitrated organics in aqueous media. Sol–gels were prepared by acid-catalyzed copolymerization of phenyltrimethoxysilane (PTMOS) and tetramethoxysilane (TMOS) and were spin-coated onto ZnSe attenuated total reflection (ATR) waveguides. These sensors were investigated with respect to their enrichment properties

Markus Janotta; Manfred Karlowatz; Frank Vogt; Boris Mizaikoff

2003-01-01

474

Selective formation of isobutane and isobutene from synthesis gas over zirconia catalysts prepared by a modified sol-gel method  

Microsoft Academic Search

Zirconium oxide was synthesized by a modified sol-gel method, and was evaluated for the selective formation of isobutane and isobutene from synthesis gas. Due to increased basicity, zirconia from sol-gel preparation showed higher selectivities to iso-C[sub 4]'s while maintaining the same level of activity as zirconia prepared by calcination of zirconyl salts. The catalysts was further modified with Group I

Z. Feng; W. S. Postula; C. Erkey; C. V. Philip; A. Akgerman; R. G. Anthony

1994-01-01

475

Effect of the preparation method on the band gap of titania and platinum-titania sol-gel materials  

Microsoft Academic Search

TiO2 and PtTiO2 sol-gel materials were synthesized at pH 3 and 9 by the sol-gel process using titanium alkoxide as reactant. The resultant solids were studied by UV-Vis (diffuse reflectance) spectroscopy. An evaluation of the band gap (Eg) was done in samples thermally treated at different temperatures. VO2?+ vacancies are formed in titania and platinum-titania samples by dehydroxylation when the

E. Sanchez; T. Lopez

1995-01-01

476

The effect of sequence of sol-gel multilayer coatings deposition on corrosion behaviour of stainless steel 316L  

Microsoft Academic Search

The possibility of producing protective coatings by the sol-gel process is discussed. Metaloorganic complexes open new possibilities for the syntheses of ceramic materials. The most important applications of Si alkoxides for the synthesis of inorganic-inorganic composites are presented. The SiO2 protective coatings on surgical stainless steel 316L have been synthesized by the sol-gel techniques. The multi-layer coatings were deposited by

JACEK GRZEGORZ; JAN MASALSKI

477

Enhancement of the Photochromic Performance of Spirooxazine in Sol-Gel Derived Organic-Inorganic Hybrid Matrices by Additives  

Microsoft Academic Search

Organic-inorganic hybrid materials synthesized via sol-gel processing are excellent solid matrices for photochromic dyes like spirooxazine, and the photochromic performance can be further enhanced by introducing suitable additives. This work describes the effects of additives on the photochromic intensity (? A0), decolouration rate (k) and photostability of spirooxazine in sol-gel derived organic-inorganic hybrid matrices. They include fluoro-alkylsilane (FAS), bisphenol A

L. Hou; H. Schmidt; B. Hoffmann; M. Mennig

1997-01-01

478

Novel hybrid organic-inorganic sol-gel materials based on highly efficient heterocyclic push-pull chromophores  

Microsoft Academic Search

We report the synthesis of sol-gel materials based on highly efficient heterocycle-based push-pull chromophores showing second- and third-order nonlinear optical activity. We show the proper functionalization of the best performing chromophores and their incorporation into a hybrid organic- inorganic sol-gel matrix. Different types of functionalization of the active molecule have been considered, including hydroxyl and alkoxysilyl end-groups. The functionalization strategy

Alessandro Abbotto; Renato Bozio; Giovanna Brusatin; Antonio Facchetti; Massimo Guglielmi; Plinio Innocenzi; Moreno Meneghetti; Giorgio A. Pagani; Raffaella Signorini

1999-01-01

479

Nanoporous tree-like SiO 2 films fabricated by sol–gel assisted electrostatic spray deposition  

Microsoft Academic Search

A novel nanoporous tree-like SiO2 film was synthesized by a sol–gel assisted electrostatic spray deposition (SG-ESD) approach. The sol–gel process employed was better to create SiO2 with linear cross-link chains for the electrostatic spray deposition. From electron microscopic study, it was found that the as-deposited SiO2 films possess nanoporous tree-like morphology in macroscale; and monodispersed hollow nanoporous spherical structure in

Xifei Li; Abirami Dhanabalan; Xiangbo Meng; Lin Gu; Xueliang Sun; Chunlei Wang

480

Fluorescence spectroscopic study of dip coated sol-gel thin film internal environment using fluorescent probes Hoechst33258 and Pyranine  

Microsoft Academic Search

The characterization of physicochemical properties of the internal environment of sol-gel thin films is required for understanding\\u000a and designing applications in optical biosensors. We have investigated the dip coated tetraethyl-orthosilicate (TEOS) derived\\u000a sol-gel thin films deposited on microscopic glass cover slips using molar ratio (water or ethanol \\/ TEOS) R=32 using fluorescence spectroscopic measurements (emission, lifetime and anisotropy) on entrapped

Bhaskar. M. Murari; Sneh. Anand; Nivedita. K. Gohil; Nabo. K. Chaudhury

2007-01-01

481

Preparation of samaria-doped ceria for solid-oxide fuel cell electrolyte by a modified sol-gel method  

Microsoft Academic Search

Samaria-doped ceria powders were prepared by the sol-gel method with different processes. The characteristics of the sample were investigated by particle size distribution, X-ray diffraction, crystallite size, and density analyses. A modified process of the sol-gel method was proposed in this work. It involves treating the gel with high-carbon (long chain, high boiling point) alcohol. It yields near-completely soft-agglomerated nanocrystalline

G. B. Jung; T. J. Huang; M. H. Huang; C. L. Chang

2001-01-01

482

An optical pH sensor with extended detection range based on fluoresceinamine covalently bound to sol–gel support  

Microsoft Academic Search

An optical pH sensor was developed based on the fluorophor, fluoresceinamine isomer II (FA), covalently immobilized in a sol–gel matrix. This sol–gel matrix was created by the copolymerization of two precursors, methyltriethoxysilane (MTES) and 3-glycidoxypropyltrimethoxysilane (GPTMS), in an ethanolic solution. Fluoresceinamine was covalently bound to the glycidoxypropyl chain group of GPTMS, thereby preventing it from leaching. Moreover, the immobilization of

Hong Dinh Duong; Ok-Jae Sohn; Hung T. Lam; Jong Il Rhee

2006-01-01

483

Sol–gels with fiber-optic chemical sensor potential: Effects of preparation, aging, and long-term storage  

Microsoft Academic Search

The features of sol–gels, incorporating pH-sensitive dyes, designed as potential substrates for fiber-optic chemical sensors, have been investigated in terms of a variety of characteristics resulting from the preparation methods used and following the storage of samples for a period of several years. These materials, organically doped sol–gels, have been used as the heart of a number of prototype chemical

G. E. Badini; K. T. V. Grattan; A. C. C. Tseung

1995-01-01