Ceramic protective coatings applied by sol-gel or electrophoresis

International Nuclear Information System (INIS)

Stoch, A.

1993-01-01

Sol-gel and electrophoresis are the complementary techniques which may be used for obtaining the ceramic coatings. The composition of such a coatings depends on the composition of electrophoresis bath or sol solution. Thermal treatment is used for densifying the coating and promoting the adherence of coating to the substrate. In presented work silica, silica-alumina or alumina coatings are applied by sol-gel dip coating procedure on steel, aluminium or ceramic substrates. Electrophoresis is employed for obtaining zirconia, alumina or hydroxyapatite coatings on stainless steel. (author). 7 refs

Environmentally benign sol-gel antifouling and foul-releasing coatings.

Science.gov (United States)

Detty, Michael R; Ciriminna, Rosaria; Bright, Frank V; Pagliaro, Mario

2014-02-18

Biofouling on ships and boats, characterized by aquatic bacteria and small organisms attaching to the hull, is an important global issue, since over 80000 tons of antifouling paint is used annually. This biofilm, which can form in as little as 48 hours depending on water temperature, increases drag on watercraft, which greatly reduces their fuel efficiency. In addition, biofouling can lead to microbially induced corrosion (MIC) due to H2S formed by the bacteria, especially sulfate-reducing bacteria. When the International Maritime Organization (IMO) international convention banned the use of effective but environmentally damaging coatings containing tributyl tin in 2008, the development of clean and effective antifouling systems became more important than ever. New nonbiocidal coatings are now in high demand. Scientists have developed new polymers, materials, and biocides, including new elastomeric coatings that they have obtained by improving the original silicone (polydimethylsiloxane) formulation patented in 1975. However, the high cost of silicones, especially of fluoropolymer-modified silicones, has generally prevented their large-scale diffusion. In 2009, traditional antifouling coatings using cuprous oxide formulated in copolymer paints still represented 95% of the global market volume of anti-fouling paints. The sol-gel nanochemistry approach to functional materials has emerged as an attractive candidate for creating low fouling surfaces due to the unique structure and properties of silica-based coatings and of hybrid inorganic-organic silicas in particular. Sol-gel formulations easily bind to all types of surfaces, such as steel, fiberglass, aluminum, and wood. In addition, they can cure at room temperature and form thin glassy coatings that are markedly different from thick silicone elastomeric foul-releasing coatings. Good to excellent performance against biofouling, low cure temperatures, enhanced and prolonged chemical and physical stability, ease of

Synthesis of phthalocyanine doped sol-gel materials

Science.gov (United States)

Dunn, Bruce

1993-01-01

The synthesis of sol-gel silica materials doped with three different types of metallophthalocyanines has been studied. Homogeneous materials of good optical quality were prepared and the first optical limiting measurements of dyes in sol-gel hosts were carried out. The properties of these solid state limiters are similar to limiters based on phthalocyanine (Pc) in solution. Sol-gel silica materials containing copper, tin and germanium phthalocyanines were investigated. The initial step in all cases was to prepare silica sols by the sonogel method using tetramethoxy silane (TMOS), HCl and distilled water. Thereafter, the synthesis depended upon the specific Pc and its solubility characteristics. Copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPc4S) is soluble in water and various doping levels (1 x 10 (exp -4) M to 1 x 10 (exp -5) M) were added to the sol. The group IV Pc's, SnPc(OSi(n-hexyl)3)2 and GePc(OSi(n-hexyl)3)2, are insoluble in water and the process was changed accordingly. In these cases, the compounds were dissolved in THF and then added to the sol. The Pc concentration in the sol was 2 x 10(exp -5)M. The samples were then aged and dried in the standard method of making xerogel monoliths. Comparative nanosecond optical limiting experiments were performed on silica xerogels that were doped with the different metallophthalocyanines. The ratio of the net excited state absorption cross section (sigma(sub e)) to the ground state cross section (sigma(sub g)) is an important figure of merit that is used to characterize these materials. By this standard the SnPc sample exhibits the best limiting for the Pc doped sol-gel materials. Its cross section ratio of 19 compares favorably with the value of 22 that was measured in toluene. The GePc materials appear to not be as useful as those containing SnPc. The GePc doped solids exhibit a higher onset energy (2.5 mj and lower cross section ratio, 7. The CuPc4S sol-gel material has a still lower cross

Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby

Science.gov (United States)

Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)

2002-01-01

A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.

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

Science.gov (United States)

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

2012-11-01

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

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 Research Council Canada - National Science Library

Schmidt, Helmut

1998-01-01

...; Sol-Gel Coatings on Large Glass Substrates for Multilayer Interference Systems; A SiO2-ZrO2 Gel Film doped with Organic Pigments Made by the Sol-Gel Method for Contrast Enhancement of Color Picture Tubes...

Hydrogen permeation through sol-gel-coated iron during galvanostatic charging

International Nuclear Information System (INIS)

Zakorchemna, I.; Carmona, N.; Zakroczymski, T.

2008-01-01

One-layer sol-gel silica-zirconia and two-layer silica-zirconia and zirconia coatings were deposited on one side of iron membranes by spin-coating, densified in air and annealed up to 800 deg. C in vacuum. Hydrogen permeation through the membranes, coated and uncoated, polarised cathodically under galvanostatic control in 0.1 M NaOH solution was studied using the electrochemical permeation technique. During the initial period, the effect of the sol-gel coatings was insignificant. However, the coatings quite efficiently prevented the iron surface become more active to hydrogen entry during a long-lasting cathodic polarisation. In addition, the electrochemical-corrosion behaviour of the coated iron and the effect of the sol-gel coatings on the effective diffusivity of hydrogen in the coated membranes were studied. On the basis of the polarisation curves and the hydrogen permeation data it was proved that the sol-gel coatings blocked the iron surface for the hydrogen evolution reaction and, consequently, for the hydrogen entry into iron. The effective coating coverage was determined by comparison of the hydrogen fluxes permeating the coated and uncoated membranes. Finally the real concentration of hydrogen beneath the uncoated iron sites and the amount of hydrogen stored in a membrane were evaluated

Efficacy of a new tan doped sol-gel sorbent for uptake of zinc

International Nuclear Information System (INIS)

Khan, A.; Ahmed, S.; Riaz, M.; Mahmood, F.; Younas Khokhar, M.

2003-01-01

A TAN (1-(2-Thiazolylazo)-2-naphthol) doped sol gel silica sorbent (reddish colour, porous, stable, hard, non-swelling) were prepared and investigated for the removal of Zn (II) from aqueous solutions. The kinetics, adsorption isotherm, equilibration time and pH effect on the removal were studied from non competitive aqueous solution to optimize the conditions to be utilized on a large scale. Fast equilibration was observed and adsorption equilibria were reached within 30 minutes. Adsorption of zinc ions on the blank (un-doped) sol gel was found negligible. The maximum adsorption of Zn (II) ions onto the TAN doped sol-gel from single solutions were 2.33 mg/g (0.035 mmol/g). TAN doped sol gel can be regenerated through washing with a solution of 0.1 M HCl solution. The maximum regeneration value was as high as 99.0%. The TAN-doped sol gel silica is suitable at least for four adsorption-desorption cycles without experiencing considerable loss of adsorption capacity. The uptake route and the nature of the Zn-TAN complex have been discussed. (orig.)

Sol-gel coatings on carbon/carbon composites

International Nuclear Information System (INIS)

Sim, S.M.; Krabill, R.M.; Dalzell, W.J. Jr.; Chu, P.Y.; Clark, D.E.

1986-01-01

The need for structural materials that can withstand severe environments up to 4000 0 F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates

Sol-gel antireflective coating on plastics

Science.gov (United States)

Ashley, Carol S.; Reed, Scott T.

1990-01-01

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

Antimicrobial activity of thin solid films of silver doped hydroxyapatite prepared by sol-gel method.

Science.gov (United States)

Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

2014-01-01

In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x(Ag) = 0.5 are effective against E. coli and S. aureus after 24 h.

Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

Directory of Open Access Journals (Sweden)

Simona Liliana Iconaru

2014-01-01

Full Text Available In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM with energy Dispersive X-ray attachment (X-EDS, Fourier transform infrared spectroscopy (FT-IR, and glow discharge optical emission spectroscopy (GDOES. These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with xAg=0.5 are effective against E. coli and S. aureus after 24 h.

Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

Science.gov (United States)

Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

2014-01-01

In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x Ag = 0.5 are effective against E. coli and S. aureus after 24 h. PMID:24523630

Sol-Gel Derived, Nanostructured Oxide Lubricant Coatings

National Research Council Canada - National Science Library

Taylor, Douglas

2000-01-01

In this program, we deposited oxide coatings of titanium and nickel by wet-chemical deposition methods, also referred to as sol-gel, which showed excellent tribological properties in previous investigations...

Synthesis of lithium doped zinc oxide by sol gel

International Nuclear Information System (INIS)

Meziane, K; Elhichou, A; Elhamidi, A; Almaggoussi, A; CHHIBA, M

2016-01-01

Li-doped ZnO thin films were prepared by sol-gel method and deposed on glass substrate using spin coating technique. The effects of Li on structural and optical properties were investigated. The X-ray diffraction (XRD) analysis reveals that Li incorporation leads to the great improvement of the crystalline quality of ZnO thin films. Scanning electron microscopy (SEM) images showed that nanowires are aligned nearly perpendicular to the substrate plane and are affected significantly by Li incorporation. The optical transmission of the films was higher than 80% in the visible region. It is found that the optical gap and the refractive index remain practically constant. (paper)

Low-cost growth of magnesium doped gallium nitride thin films by sol-gel spin coating method

Science.gov (United States)

Amin, N. Mohd; Ng, S. S.

2018-01-01

Low-cost sol-gel spin coating growth of magnesium (Mg) doped gallium nitride (GaN) thin films with different concentrations of Mg was reported. The effects of the Mg concentration on the structural, surface morphology, elemental compositions, lattice vibrational, and electrical properties of the deposited films were investigated. X-ray diffraction results show that the Mg-doped samples have wurtzite structure with preferred orientation of GaN(002). The crystallite size decreases and the surface of the films with pits/pores were formed, while the crystalline quality of the films degraded as the Mg concentration increases from 2% to 6. %. All the Raman active phonon modes of the wurtzite GaN were observed while a broad peak attributed to the Mg-related lattice vibrational mode was detected at 669 cm-1. Hall effect results show that the resistivity of the thin films decreases while the hole concentration and hall mobility of thin films increases as the concentration of the Mg increases.

Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

Science.gov (United States)

López, A. J.; Rico, A.; Rodríguez, J.; Rams, J.

2010-08-01

Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

Sol-gel derived antireflective coatings for silicon

Energy Technology Data Exchange (ETDEWEB)

Brinker, C J; Harrington, M S

1981-08-01

The preparation of TiO2-SiO2 AR coatings, containing from 30 to 95 mol % TiO2, from alkoxide precursor solutions (titanium tetraethoxide and silicon tetraethoxide) by a sol-gel process is presented. The preparation of the solutions is described, which involves the separate partial hydrolysis of one or both alkoxides prior to their mixing (Yoldas, 1980). The solutions are applied to polished, circular (1 and 2 in. diameter) silicon wafers by a spinning process. The coated wafers are successively heated in air at each of the following temperatures: 200, 300, 350, 400, and 450 C, and optical measurements are performed on them after each heat treatment. The durability of 90 and 95% TiO2 coatings is evaluated in both acidic and basic environments, and reflectivity, film thickness, and refractive index are measured as a function of exposure time. It is shown that sol-gel films applied at 400 C reveal broad regions of antireflectance compared to other titanium-based films.

Ultraviolet Stimulated Emission from Sol-Gel Spin Coated ZnO Thin Films

Directory of Open Access Journals (Sweden)

Ahmed S. Razeen

2017-01-01

Full Text Available Low cost ultraviolet stimulated emission has been generated using optical excitation of ZnO thin films deposited by sol-gel spin coating on n+ As-doped 100 Si-substrate. The number of deposited layers and the heat treatment have been investigated to obtain a film that can generate stimulated emission under optical excitation. The optimum condition for preparation of the film has been presented. X-ray diffraction and scanning electron microscope have been used for structural and morphological investigations. Input-output intensity dependence and spectral width, peak emission wavelength, and the quantum efficiency versus the pump intensity have been presented. A quantum efficiency of about 24.2% has been reported, a power exponent higher than 8 has been obtained in input-output intensity dependence, and a threshold of about 23 Mw/cm2 has been evaluated for the samples. The mechanism by which stimulated emission occurs has been discussed. The results show that sol-gel spin coating is a promising method for generating ultraviolet stimulated emission from ZnO thin films.

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

Science.gov (United States)

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

2009-09-01

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.

Sol-gel synthesis of lanthanum-gallate-based ceramic coatings

International Nuclear Information System (INIS)

Golubko, N.V.; Kaleva, G.M.; Roginskaya, Yu.E.; Politova, E.D.

2007-01-01

Phase-pure (La 0.9 Sr 0.1 )(Ga 0.7 Fe 0.3 )O 3-y and (Sr 1.8 La 0.2 )(GaFe)O 5.1 solid solutions with the perovskite and brownmillerite structures have been prepared from salt solutions by sol-gel processing at temperatures from 570 to 870 K. Ceramic coatings up to 100 μm in thickness have been produced by applying suspensions of the sol-gel powders to various substrates. The structure and microstructure of the ceramic coatings have been studied by X-ray diffraction and scanning electron microscopy [ru

Ceria nanoparticles vis-à-vis cerium nitrate as corrosion inhibitors for silica-alumina hybrid sol-gel coating

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, R.V. [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Aruna, S.T., E-mail: staruna194@gmail.com [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Sampath, S. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012 (India)

2017-01-30

Highlights: • Corrosion protection efficiency comparison of ceria nanoparticles and cerium nitrate. • Silica-alumina hybrid coating exhibited good barrier protection. • Detailed XPS study confirm the hybrid structure and presence of Ce species in coating. • Loss of cerium ions not prevalent in ceria doped coating unlike that of cerium nitrate. • Ceria increased the coating integrity, corrosion inhibition and barrier protection. - Abstract: The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and cerium nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing cerium nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings.

Doped indium nitride thin film by sol-gel spin coating method

Science.gov (United States)

Lee, Hui San; Ng, Sha Shiong; Yam, Fong Kwong

2017-12-01

In this study, magnesium doped indium nitride (InN:Mg) thin films grown on silicon (100) substrate were prepared via sol-gel spin coating method followed by nitridation process. A custom-made tube furnace was used to perform the nitridation process. Through this method, the low dissociation temperature issue of InN:Mg thin films can be solved. The deposited InN:Mg thin films were investigated using various techniques. The X-rays diffraction results revealed that two intense diffraction peaks correspond to wurtzite structure InN (100), and InN (101) were observed at 29° and 33.1° respectively. Field emission scanning electron microscopy images showed that the surface of the films exhibits densely packed grains. The elemental composition of the deposited thin films was analyzed using energy dispersive X-rays spectroscopy. The detected atomic percentages for In, N, and Mg were 43.22 %, 3.28 %, and 0.61 % respectively. The Raman spectra showed two Raman- and infrared-active modes of E2 (High) and A1 (LO) of the wurtzite InN. The band gap obtained from the Tauc plot showed around 1.74 eV. Lastly, the average surface roughness measured by AFM was around 0.133 µm.

Electrochemical corrosion behavior of composite MAO/sol-gel coatings on magnesium alloy AZ91D using combined micro-arc oxidation and sol-gel technique

International Nuclear Information System (INIS)

Shang Wei; Chen Baizhen; Shi Xichang; Chen Ya; Xiao Xiang

2009-01-01

Protective composite coatings were obtained on a magnesium alloy by micro-arc oxidation (MAO) and sol-gel technique. The coatings consisted of a MAO layer and a sol-gel layer. The microstructure and composition of the MAO coating and the composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X-rays (EDX). Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and total immersion tests were used to evaluate the corrosion behavior of these coatings in a 3.5 wt.% NaCl solution. The results show that the sol-gel layer provides corrosion protection by physically sealing the pores in the MAO coating and acting as a barrier. The composite coatings can suppress the corrosion process by preventing the corrosive ions from transferring or diffusing to the magnesium alloy substrate. This enhances the corrosion resistance of the magnesium alloy AZ91D significantly

Dip coating of sol-gels

Science.gov (United States)

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

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 (less than 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. These phenomena were studied 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.

Minimally Adhesive, Advanced Non-toxic Coatings of Dendrimeric Catalysts in Sol-Gel Matrices

Science.gov (United States)

2015-10-19

Catalysts in Sol -Gel Matrices 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-09-1-0217 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Detty, Michael R. 5d...Technical Report for ONR N00014-09-1-0217 Minimally Adhesive, Advanced Non-toxic Coatings of Dendrimeric Catalysts in Sol -Gel Matrices Michael R. Detty, PI...Environmentally benign sol -gel antifouling and foul-releasing coatings. Ace. Chem. Res. 2014, 47, 678-687. 11) Alberto, E. E.; Müller, L. M

Modified sol-gel coatings for biotechnological applications

Energy Technology Data Exchange (ETDEWEB)

Beganskiene, A [Department of General and Inorganic Chemistry, Vilnius University, Vilnius LT-03225 (Lithuania); Raudonis, R [Department of General and Inorganic Chemistry, Vilnius University, Vilnius LT-03225 (Lithuania); Jokhadar, S Zemljic [Faculty of Medicine, Institute of Biophysics, Lipiceva 2, Ljubljana SI-1000 (Slovenia); Batista, U [Faculty of Medicine, Institute of Biophysics, Lipiceva 2, Ljubljana SI-1000 (Slovenia); Kareiva, A [Department of General and Inorganic Chemistry, Vilnius University, Vilnius LT-03225 (Lithuania)

2007-12-15

The modified sol-gel derived silica coatings were prepared and characterized. The amino and methyl groups were introduced onto the colloidal silica. The silica coatings with different wettability properties: coloidal silica (water contact angle 17 deg.), polysiloxane (61 deg.), methyl-modified (158 deg. and 46 deg.) coatings samples were tested for CaCo-2 cells proliferation. Methyl-modified coating (46 deg.) proved to be the best substrate for cell proliferation. CaCo-2 cell proliferation two days post seeding was significantly faster on almost laminine, fibronectin and collagen-1 coated samples compared to corresponding controls.

Analyses of laser and furnace treated sol-gel coatings

NARCIS (Netherlands)

De Hosson, JT; De Haas, M; Sudarshan, TS; Jeandin, M; Khor, KA

1998-01-01

Here we explore a new method that allows thin films to be made with almost any composition and degree of porosity by means of a combination of sol-gel and laser technology. Results are presented for furnace and laser treated TEOTI-(tetraethylorthotitanate as sol precursor) coated silicon samples.

Transparent Hydrophobic Coating by Sol Gel Method

International Nuclear Information System (INIS)

Mohd Hamzah Harun; Nik Ghazali Nik Salleh; Mahathir Mohamed; Mohd Sofian Alias

2016-01-01

Transparent hydrophobic coating of inorganic based tetra orthosilicate (TEOS) was prepared by sol gel method by varying fluoroalkylsilane (FAS) content which works as hydrophobic agent. Surface contact angle, transmittance degree and surface morphology were characterized for each sample. All samples show good transparency which was confirmed by UV visible spectroscopy. The hydrophobicity obtained increases with FAS content indicates that FAS is best candidate to induce hydrophobicity for inorganic coating. (author)

Transparent conducting sol-gel ATO coatings for display applications by an improved dip coating technique

International Nuclear Information System (INIS)

Guzman, G.; Dahmani, B.; Puetz, J.; Aegerter, M.A.

2006-01-01

Transparent conducting coatings of sol-gel ATO (antimony-doped tin oxide) were used to improve surface smoothness of commercial sputter-deposited ITO (indium tin oxide) coatings for application as display electrodes. In order to overcome the deteriorating evaporation-cooling during dip coating, the coating solution was heated moderately to 25 deg. C thus providing the substrate with the required heat. This way, the surface roughness of the ITO could be reduced with an only 45 nm thick ATO coating to R pv = 3.8 nm (R a = 0.4 nm) compared to 31 nm (3.8 nm) for the ITO substrate. Another benefit of such additional coating is the possibility to tailor surface properties of the electrodes in wide ranges. This was used to increase the work function of the ITO substrate from initially 4.3-4.6 eV to about 4.8-5.2 eV by the ATO coating

SOL-GEL SILICA-BASED Ag–Ca–P COATINGS WITH AGRESSIVE PRETREATMENT OF TITANIUM SUBSTRATE

Directory of Open Access Journals (Sweden)

ELENA BORSHCHEVA

2011-12-01

Full Text Available The aim of the experiment was the obtaining of thin silica coatings on titanium by sol-gel method, using mechanical (SiC - paper No.180 and chemical (leaching in HF pretreatments of the titanium substrates. The solutions were based on TEOS. For the sol-gel dipping process 4 different solutions were prepared: silica, silica with AgNO3 and silica + AgNO3 with brushite (CaHPO4·2H2O or monetite (CaHPO4 powders. The solutions were aged for 7 and 14 days at laboratory temperature. After sol-gel dip-coating process the samples were dried and fired. The adhesion of fired coatings was measured by tape test according to ASTM procedure and the bioactivity of the coatings was tested using in vitro test. The surfaces of the samples after firing, tape test and in vitro test were observed with the optical and electron microscopes. The firing results showed that silica-silver coatings did not change, brushite sol-gel coatings have cracked and the monetite sol-gel coatings have cracked also, but less than brushite ones. In spite of coating´s crackings, the square’s frames made on the surfaces were without any breakdowns after tape tests and the adhesion of all coatings was very good, classified by the highest grade 5. The results of in vitro tests showed that all coatings interacted with simulated body fluid (SBF. After exposition in SBF the new layer formed on substrates. In case of 7 days aged coatings containing brushite the new layer was uniform and compact. In case of 7 days aged coatings containing monetite the new layer was formed by crystals aggregated tightly together. The monetite and brushite coatings prepared from 14 days aged sol were the same as previous ones, but they were thicker. X-ray analyses after in vitro test confirmed dellaite, titanate and hydroxyapatite phases.

The role of crosslinkers in epoxy-amine crosslinked silicon sol-gel barrier protection coatings

International Nuclear Information System (INIS)

Vreugdenhil, A.J.; Gelling, V.J.; Woods, M.E.; Schmelz, J.R.; Enderson, B.P.

2008-01-01

The search for chromate replacements in corrosion prevention materials has identified the use of hybrid sol-gel coatings as one, very promising approach. Appropriately functionalized hybrid sol-gel materials can be crosslinked to enhance their chemical durability and mechanical strength. In this work, we evaluate three crosslinkers used in a tetramethoxysilane-glycidoxypropyltrimethoxysilane binary sol-gel system in order to identify the role of the crosslinkers in corrosion protection. The crosslinkers examined were ethylenediamine, N-aminethylepiperazine, and diethylenetriamine. The sol-gel coatings were examined by contact angle, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). Circuit modeling of the EIS results yielded valuable insights into the significant differences between the durabilities of the variously crosslinked coatings. Crosslinker hydrophobicity was identified as not playing a significant role whereas the number of reactive sites per crosslinker and the resulting morphology of the material may be an important parameter

Processing, adhesion and electrical properties of silicon steel having non-oriented grains coated with silica and alumina sol-gel

International Nuclear Information System (INIS)

Vasconcelos, D.C.L.; Orefice, R.L.; Vasconcelos, W.L.

2007-01-01

Silicon steels having non-oriented grains are usually coated with a series of inorganic or organic films to be used in electrical applications. However, the commercially available coatings have several disadvantages that include poor adhesion to the substrates, low values of electrical resistance and degradation at higher temperatures. In this work, silica and alumina sol-gel films were deposited onto silicon steel in order to evaluate the possibility of replacing the commercially available coatings by these sol-gel derived materials. Silica and alumina sol-gel coatings were prepared by dipping silicon steel samples into hydrolyzed silicon or aluminum alkoxides. Samples coated with sol-gel films were studied by scanning electron microscopy, energy dispersive spectroscopy and infrared spectroscopy. Adhesion between silicon steel and sol-gel films was measured by using several standard adhesion tests. Electrical properties were evaluated by the Franklin method. Results showed that homogeneous sol-gel films can be deposited onto silicon steel. Thicknesses of the films could be easily managed by altering the speed of deposition. The structure of the films could also be tailored by introducing additives, such as nitric acid and N,N-dimethyl formamide. Adhesion tests revealed a high level of adhesion between coatings and metal. The Franklin test showed that sol-gel films can produce coated samples with electrical resistances suitable for electrical applications. Electrical properties of the coated samples could also be manipulated by altering the structure of the sol-gel films or by changing the thickness of them

Sol-gel coatings on large area glass sheets for electrochromic devices

NARCIS (Netherlands)

Vroon, Z.A.E.P.; Spee, C.I.M.A.

1997-01-01

The preparation of vanadium and tungsten oxide coatings is described using vanadium oxide tri-2-propoxide/2-propanol and tungsten penta-ethoxide/2-propanol solutions. These solutions are dip coated onto K-glass substrates and cured. For vanadium oxide coatings it is shown that sol-gel/dip coat

Biological influence of Ca/P ratio on calcium phosphate coatings by sol-gel processing

Energy Technology Data Exchange (ETDEWEB)

Catauro, M., E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29 (Italy); Papale, F. [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29 (Italy); Sapio, L.; Naviglio, S. [Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples (Italy)

2016-08-01

The objective of this work has been to develop low temperature sol-gel glass coatings to modify the substrate surface and to evaluate their bioactivity and biocompatibility. Glasses, based on SiO{sub 2}·CaO·P{sub 2}O{sub 5}, were synthesized by the sol-gel technique using tetraethyl orthosilicate, calcium nitrate tetrahydrate and triethyl phosphate as precursors of SiO{sub 2}, CaO and P{sub 2}O{sub 5}, respectively. Those materials, still in the sol phase, have been used to coat substrates by means of the dip-coating technique. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) has been used for characterize coatings and a microstructural analysis has been obtained using scanning electron microscopy (SEM). The potential applications of the coatings in the biomedical field were evaluated by bioactivity and biocompatibility tests. The coated substrate was immersed in simulated body fluid (SBF) for 21 days and the hydroxyapatite deposition on its surface was subsequently evaluated via SEM-EDXS analysis, as an index of bone-bonding capability. In order to study the cell behavior and response to our silica based materials, prepared via the sol-gel method, with various Ca/P ratio and coating substrate, we have used the human osteoblast-like U2OS cell line. - Highlights: • Coatings consisting of SiO{sub 2}·CaO·P{sub 2}O{sub 5} glasses were prepared via sol-gel dip coating. • Ca/P molar ratio affects the film morphology and biocompatibility. • Higher cell proliferation was found in response to higher Ca/P ratios coatings. • A growth cell proliferation inhibition was observed in response to lower Ca/P ratio.

High-power microcavity lasers based on highly erbium-doped sol-gel aluminosilicate glasses

International Nuclear Information System (INIS)

Le Ngoc Chung; Chu Thi Thu Ha; Nguyen Thu Trang; Pham Thu Nga; Pham Van Hoi; Bui Van Thien

2006-01-01

High-power whispering-gallery-mode (WGM) lasing from highly erbium-doped sol-gel aluminosilicate microsphere cavity coupled to a half-tapered optical fiber is presented. The lasing output power as high as 0.45 mW (-3.5 dBm) was obtained from sol-gel glass microsphere cavity with diameters in the range of 40-150 μm. The sol-gel method for making highly concentration Er-doped aluminosilicate glasses with Er-ion concentrations from 0.125 to 0.65 mol% of Er 3+ is described. Controlling collected lasing wavelength at each WGM is possible by adjusting the distance between the half-taper fiber and the microcavity and by diameter of the waist of half-taper fiber. Using the analytic formulas we calculated the TE and TM lasing modes and it is shown that the experimental results are in good agreement with the calculation prediction

Sol-gel bonding of silicon wafers

International Nuclear Information System (INIS)

Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Short, K.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

2005-01-01

Sol-gel bonds have been produced between smooth, clean silicon substrates by spin-coating solutions containing partially hydrolysed silicon alkoxides. The two coated substrates were assembled and the resulting sandwich fired at temperatures ranging from 60 to 600 deg. C. The sol-gel coatings were characterised using attenuated total reflectance Fourier transform infrared spectroscopy, ellipsometry, and atomic force microscopy, while the corresponding bonded specimens were investigated using scanning electron microscopy and cross-sectional transmission electron microscopy. Mechanical properties were characterised using both microindentation and tensile testing. Bonding of silicon wafers has been successfully achieved at temperatures as low as 60 deg. C. At 300 deg. C, the interfacial fracture energy was 1.55 J/m 2 . At 600 deg. C, sol-gel bonding provided superior interfacial fracture energy over classical hydrophilic bonding (3.4 J/m 2 vs. 1.5 J/m 2 ). The increase in the interfacial fracture energy is related to the increase in film density due to the sintering of the sol-gel interface with increasing temperature. The superior interfacial fracture energy obtained by sol-gel bonding at low temperature is due to the formation of an interfacial layer, which chemically bonds the two sol-gel coatings on each wafer. Application of a tensile stress on the resulting bond leads to fracture of the samples at the silicon/sol-gel interface

A review of hydroxyapatite-based coating techniques: Sol-gel and electrochemical depositions on biocompatible metals.

Science.gov (United States)

Asri, R I M; Harun, W S W; Hassan, M A; Ghani, S A C; Buyong, Z

2016-04-01

New promising techniques for depositing biocompatible hydroxyapatite-based coatings on biocompatible metal substrates for biomedical applications have continuously been exploited for more than two decades. Currently, various experimental deposition processes have been employed. In this review, the two most frequently used deposition processes will be discussed: a sol-gel dip coating and an electrochemical deposition. This study deliberates the surface morphologies and chemical composition, mechanical performance and biological responses of sol-gel dip coating as well as the electrochemical deposition for two different sample conditions, with and without coating. The review shows that sol-gel dip coatings and electrochemical deposition were able to obtain the uniform and homogeneous coating thickness and high adherent biocompatible coatings even in complex shapes. It has been accepted that both coating techniques improve bone strength and initial osseointegration rate. The main advantages and limitations of those techniques of hydroxyapatite-based coatings are presented. Furthermore, the most significant challenges and critical issues are also highlighted. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Co doping concentration on structural properties and optical parameters of Co-doped ZnO thin films by sol-gel dip-coating method.

Science.gov (United States)

Nam, Giwoong; Yoon, Hyunsik; Kim, Byunggu; Lee, Dong-Yul; Kim, Jong Su; Leem, Jae-Young

2014-11-01

The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

Sol-gel technology for biomedical engineering

International Nuclear Information System (INIS)

Podbielska, H.; Ulatowska-Jarza, A.

2005-01-01

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 developing 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 are included. It is reported that sol-gels with entrapped various molecules may be used in construction of implants and coatings with bioactive properties. It is shown how to exploit the sol-gel production route for construction of sol-gel coated fiberoptic applicators for laser therapy. The applications of bioactive materials are discussed, as well. It is demonstrated that it is possible to immobilize photosensitive compounds in sol-gel matrix without loosing their photoactivity. Some examples of sol-gel based biosensors are demonstrated, as well, showing their potential for detecting various gases, toxic substances, acidity, humidity, enzymes and biologically active agents. (authors)

A copper ion-selective electrode with high selectivity prepared by sol-gel and coated wire techniques.

Science.gov (United States)

Mazloum Ardakani, M; Salavati-Niasari, M; Khayat Kashani, M; Ghoreishi, S M

2004-03-01

A sol-gel electrode and a coated wire ion-selective poly(vinyl chloride) membrane, based on thiosemicarbazone as a neutral carrier, were successfully developed for the detection of Cu (II) in aqueous solutions. The sol-gel electrode and coated electrode exhibited linear response with Nernstian slopes of 29.2 and 28.1 mV per decade respectively, within the copper ion concentration ranges 1.0 x 10(-5) - 1.0 x 10(-1) M and 6.0 x 10(-6) - 1.0 x 10(-1) M for coated and sol-gel sensors. The coated and sol-gel electrodes show detection limits of 3.0 x 10(-6) and 6.0 x 10(-6) M respectively. The electrodes exhibited good selectivities for a number of alkali, alkaline earth, transition and heavy metal ions. The proposed electrodes have response times ranging from 10-50 s to achieve a 95% steady potential for Cu2+ concentration. The electrodes are suitable for use in aqueous solutions over a wide pH range (4-7.5). Applications of these electrodes for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu2+ ion using EDTA, are reported. The lifetimes of the electrodes were tested over a period of six months to investigate their stability. No significant change in the performance of the sol-gel electrode was observed over this period, but after two months the coated wire copper-selective electrode exhibited a gradual decrease in the slope. The selectivity of the sol-gel electrode was found to be better than that of the coated wire copper-selective electrode. Based on these results, a novel sol-gel copper-selective electrode is proposed for the determination of copper, and applied to real sample assays.

Hybrid Thin Film Organosilica Sol-Gel Coatings To Support Neuronal Growth and Limit Astrocyte Growth.

Science.gov (United States)

Capeletti, Larissa Brentano; Cardoso, Mateus Borba; Dos Santos, João Henrique Zimnoch; He, Wei

2016-10-07

Thin films of silica prepared by a sol-gel process are becoming a feasible coating option for surface modification of implantable neural sensors without imposing adverse effects on the devices' electrical properties. In order to advance the application of such silica-based coatings in the context of neural interfacing, the characteristics of silica sol-gel are further tailored to gain active control of interactions between cells and the coating materials. By incorporating various readily available organotrialkoxysilanes carrying distinct organic functional groups during the sol-gel process, a library of hybrid organosilica coatings is developed and investigated. In vitro neural cultures using PC12 cells and primary cortical neurons both reveal that, among these different types of hybrid organosilica, the introduction of aminopropyl groups drastically transforms the silica into robust neural permissive substrate, supporting neuron adhesion and neurite outgrowth. Moreover, when this organosilica is cultured with astrocytes, a key type of glial cells responsible for glial scar response toward neural implants, such cell growth promoting effect is not observed. These findings highlight the potential of organo-group-bearing silica sol-gel to function as advanced coating materials to selectively modulate cell response and promote neural integration with implantable sensing devices.

Influence of Experimental Parameters Using the Dip-Coating Method on the Barrier Performance of Hybrid Sol-Gel Coatings in Strong Alkaline Environments

Directory of Open Access Journals (Sweden)

Rita B. Figueira

2015-04-01

Full Text Available Previous studies have shown that the barrier effect and the performance of organic-inorganic hybrid (OIH sol-gel coatings are highly dependent on the coating deposition method as well as on the processing conditions. However, studies on how the coating deposition method influences the barrier properties in alkaline environments are scarce. The aim of this experimental research was to study the influence of experimental parameters using the dip-coating method on the barrier performance of an OIH sol-gel coating in contact with simulated concrete pore solutions (SCPS. The influence of residence time (Rt, a curing step between each dip step and the number of layers of sol-gel OIH films deposited on hot-dip galvanized steel to prevent corrosion in highly alkaline environments was studied. The barrier performance of these OIH sol-gel coatings, named U(400, was assessed in the first instants of contact with SCPS, using electrochemical impedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings in SCPS was monitored during eight days by macrocell current density. The morphological characterization of the surface was performed by Scanning Electronic Microscopy before and after exposure to SCPS. Glow Discharge Optical Emission Spectroscopy was used to investigate the thickness of the U(400 sol-gel coatings as a function of the number of layers deposited with and without Rt in the coatings thickness.

Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography.

Science.gov (United States)

Tran, MinhPhuong; Turner, Erica B; Segro, Scott S; Fang, Li; Seyyal, Emre; Malik, Abdul

2017-11-03

A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0-pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Neutron detector based on lithiated sol-gel glass

CERN Document Server

Wallace, S; Miller, L F; Dai, S

2002-01-01

A neutron detector technology is demonstrated based on sup 6 Li/ sup 1 sup 0 B doped sol-gel glass. The detector is a sol-gel glass film coated silicon surface barrier detector (SBD). The ionized charged particles from (n, alpha) reactions in the sol-gel film enter the SBD and are counted. Data showing that gamma-ray pulse amplitudes interfere with identifying charged particles that exit the film layer with energies below the gamma-ray energy is presented. Experiments were performed showing the effect of sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co gamma rays on the SBD detector. The reaction product energies of the triton and alpha particles from sup 6 Li are significantly greater than the energies of the Compton electrons from high-energy gamma rays, allowing the measurement of neutrons in a high gamma background. The sol-gel radiation detection technology may be applicable to the characterization of transuranic waste, spent nuclear fuel and to the monitoring of stored plutonium.

Hydrogen permeation through steel coated with erbium oxide by sol-gel method

International Nuclear Information System (INIS)

Yao Zhenyu; Suzuki, Akihiro; Levchuk, Denis; Chikada, Takumi; Tanaka, Teruya; Muroga, Takeo; Terai, Takayuki

2009-01-01

Er 2 O 3 coating is formed on austenitic stainless steel 316ss by sol-gel method. The results showed good crystallization of coating by baking in high purity flowing-argon at 973 K, and indicated that a little oxygen in baking atmosphere is necessary to crystallization of coating. The best baking temperature could be thought as 973 K, to get good crystallization of coating and avoid strong oxidation of steel substrate. The deuterium permeation test was performed for coated and bare 316ss, to evaluate the property of Er 2 O 3 sol-gel coating as a potential tritium permeation barrier. In this study, the deuterium permeability of coated 316ss is about 1-2 orders of magnitude lower than that of bare 316ss, and is about 2-3 orders of magnitude than the referred data of bare Eurofer97 and F82H martensitic steel.

Innovative Formulation Combining Al, Zr and Si Precursors to Obtain Anticorrosion Hybrid Sol-Gel Coating

Directory of Open Access Journals (Sweden)

Clément Genet

2018-05-01

Full Text Available The aim of our study is to improve the aluminium alloy corrosion resistance with Organic-Inorganic Hybrid (OIH sol-gel coating. Coatings are obtained from unusual formulation with precursors mixing: glycidoxypropyltrimethoxysilane (GPTMS, zirconium (IV propoxide (TPOZ and aluminium tri-sec-butoxide (ASB. This formulation was characterized and compared with sol formulations GPTMS/TPOZ and GPTMS/ASB. In each formulation, a corrosion inhibitor, cerium (III nitrate hexahydrate, is employed to improve the corrosion performance. Coatings obtained from sol based on GPTMS/TPOZ/ASB have good anti-corrosion performances with Natural Salt Spray (NSS resistance of 500 h for a thickness lower than 4 µm. Contact angle measurement showed a coating hydrophobic behaviour. To understand these performances, nuclear magnetic resonance (NMR analyses were performed, results make sol-gel coating condensation evident and are in very good agreement with previous results.

Innovative Formulation Combining Al, Zr and Si Precursors to Obtain Anticorrosion Hybrid Sol-Gel Coating.

Science.gov (United States)

Genet, Clément; Menu, Marie-Joëlle; Gavard, Olivier; Ansart, Florence; Gressier, Marie; Montpellaz, Robin

2018-05-10

The aim of our study is to improve the aluminium alloy corrosion resistance with Organic-Inorganic Hybrid (OIH) sol-gel coating. Coatings are obtained from unusual formulation with precursors mixing: glycidoxypropyltrimethoxysilane (GPTMS), zirconium (IV) propoxide (TPOZ) and aluminium tri-sec-butoxide (ASB). This formulation was characterized and compared with sol formulations GPTMS/TPOZ and GPTMS/ASB. In each formulation, a corrosion inhibitor, cerium (III) nitrate hexahydrate, is employed to improve the corrosion performance. Coatings obtained from sol based on GPTMS/TPOZ/ASB have good anti-corrosion performances with Natural Salt Spray (NSS) resistance of 500 h for a thickness lower than 4 µm. Contact angle measurement showed a coating hydrophobic behaviour. To understand these performances, nuclear magnetic resonance (NMR) analyses were performed, results make sol-gel coating condensation evident and are in very good agreement with previous results.

Sol-gel derived bioactive coating on zirconia: Effect on flexural strength and cell proliferation.

Science.gov (United States)

Shahramian, Khalil; Leminen, Heidi; Meretoja, Ville; Linderbäck, Paula; Kangasniemi, Ilkka; Lassila, Lippo; Abdulmajeed, Aous; Närhi, Timo

2017-11-01

The purpose of this study was to evaluate the effect of sol-gel derived bioactive coatings on the biaxial flexural strength and fibroblast proliferation of zirconia, aimed to be used as an implant abutment material. Yttrium stabilized zirconia disc-shaped specimens were cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n = 15) were fabricated, zirconia with sol-gel derived titania (TiO 2 ) coating, zirconia with sol-gel derived zirconia (ZrO 2 ) coating, and non-coated zirconia as a control. The surfaces of the specimens were analyzed through images taken using a scanning electron microscope (SEM), and a non-contact tapping mode atomic force microscope (AFM) was used to record the surface topography and roughness of the coated specimens. Biaxial flexural strength values were determined using the piston-on-three ball technique. Human gingival fibroblast proliferation on the surface of the specimens was evaluated using AlamarBlue assay™. Data were analyzed using a one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Additionally, the biaxial flexural strength data was also statistically analyzed with the Weibull distribution. The biaxial flexural strength of zirconia specimens was unaffected (p > 0.05). Weibull modulus of TiO 2 coated and ZrO 2 coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO 2 showed significantly lower fibroblast proliferation compared to other groups (p sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO 2 coated specimens showed significantly lower cell proliferation after 12 days than TiO 2 coated or non-coated control. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2401-2407, 2017. © 2016 Wiley Periodicals, Inc.

Biological influence of Ca/P ratio on calcium phosphate coatings by sol-gel processing.

Science.gov (United States)

Catauro, M; Papale, F; Sapio, L; Naviglio, S

2016-08-01

The objective of this work has been to develop low temperature sol-gel glass coatings to modify the substrate surface and to evaluate their bioactivity and biocompatibility. Glasses, based on SiO2·CaO·P2O5, were synthesized by the sol-gel technique using tetraethyl orthosilicate, calcium nitrate tetrahydrate and triethyl phosphate as precursors of SiO2, CaO and P2O5, respectively. Those materials, still in the sol phase, have been used to coat substrates by means of the dip-coating technique. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) has been used for characterize coatings and a microstructural analysis has been obtained using scanning electron microscopy (SEM). The potential applications of the coatings in the biomedical field were evaluated by bioactivity and biocompatibility tests. The coated substrate was immersed in simulated body fluid (SBF) for 21days and the hydroxyapatite deposition on its surface was subsequently evaluated via SEM-EDXS analysis, as an index of bone-bonding capability. In order to study the cell behavior and response to our silica based materials, prepared via the sol-gel method, with various Ca/P ratio and coating substrate, we have used the human osteoblast-like U2OS cell line. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of silane on the structure of polystyrene prepared by sol-gel coatings via UV curing

Directory of Open Access Journals (Sweden)

Balbay Senay

2017-01-01

Full Text Available Light, heat, oxygen, moisture, ozone, atmospheric pollution and biological effects are the most important effectives wreak to chemical degradation in the polymer structure. In result of chemical degradation on the polymer consist of problems such as discoloration, brittleness, surface cracks, perspiration, crumbling, smell, surface acidity. In this work, it is aimed to improve the problem of the polystyrene (PS material against chemical degradation. For this reason, PS is coated with silica sol-gel hybrid coating. Silica sol-gel was synthesized by using vinyltrimethoxysilane (VTMS as a cross-linker and tetraethylorthosilicate (TEOS as a silica source. Firstly, four different pre-treatment technique (oven, vacuum oven, lyophilizer and freezing was studied to determine the most suitable pre-treatment technique for coating on PS substrate of sol-gel prepared with initial formulation (S1. A freezing technique gave the best results for coating sample. The change of surface colour of coated PS was measured by CIE L*a*b* methods. Secondly, the most suitable curing agent (Irgacure 184, Irgacure 819, Darocur 1173 and TiO2 as crystalline anatase phase was determined to coat the sol-gel on PS. It was determined to the lowest yellowing of PS surface hybrid coated as UV curing of TEOS sol modified by VTMS and TiO2 as photo-initiators. Finally, the chemical and morphological structure of the coated PS samples was determined by FT-IR and SEM instruments, respectively.

Structural, optical and magnetic properties of nanocrystalline Co-doped ZnO thin films grown by sol-gel

Energy Technology Data Exchange (ETDEWEB)

Kayani, Zohra Nazir; Shah, Iqra; Zulfiqar, Bareera; Sabah, Aneeqa [Lahore College for Women Univ., Lahore (Pakistan); Riaz, Saira; Naseem, Shahzad [Univ. of the Punjab, Lahore (Pakistan). Centre of Excellence in Solid State Physics

2018-04-01

Cobalt-doped ZnO thin films have been deposited using a sol-gel route by changing the number of coats on the substrate from 6 to 18. This project deals with various film thicknesses by increasing the number of deposited coats. The effect of thickness on structural, magnetic, surface morphology and optical properties of Co-doped ZnO thin film was studied. The crystal structure of the Co-doped ZnO films was investigated by X-ray diffraction. The films have polycrystalline wurtzite hexagonal structures. A Co{sup 2+} ion takes the place of a Zn{sup 2+} ion in the lattice without creating any distortion in its hexagonal wurtzite structure. An examination of the optical transmission spectra showed that the energy band gap of the Co-doped ZnO films increased from 3.87 to 3.97 eV with an increase in the number of coatings on the substrate. Ferromagnetic behaviour was confirmed by measurements using a vibrating sample magnetometer. The surface morphology of thin films was assessed by scanning electron microscope. The grain size on the surface of thin films increased with an increase in the number of coats.

Synthesis and characterization of erbium-doped SiO2-TiO2 thin films prepared by sol-gel and dip-coating techniques onto commercial glass substrates as a route for obtaining active GRadient-INdex materials

International Nuclear Information System (INIS)

Gómez-Varela, Ana I.; Castro, Yolanda; Durán, Alicia; De Beule, Pieter A.A.; Flores-Arias, María T.; Bao-Varela, Carmen

2015-01-01

In this work, SiO 2 -TiO 2 films doped with erbium were prepared by dip-coating sol-gel process onto commercial glass substrates. The surface morphology of the films was characterized using atomic force microscopy, while thickness, refractive index, extinction coefficient and porosity of the films were determined by ellipsometric measurements in a wavelength region of 400-1000 nm. Optical constants and porosity were found to vary with erbium concentration. The proof of principle presented in this paper is applicable to systems of different nature by tailoring the sol-gel precursors in such a way that active GRadient-INdex media described by a complex, parabolic-like refractive index distribution for beam shaping purposes is obtained. - Highlights: • Sol-gel route for preparation of active GRadient-INdex materials is proposed. • SiO 2 -TiO 2 films doped with erbium were prepared by dipping onto commercial glasses. • Morphological and optical characterization of the samples was performed. • Optical constants and porosity were found to vary with erbium concentration. • Refractive index diminishes with dopant content; the contrary occurs for porosity

Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

Science.gov (United States)

Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

2007-01-01

Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications. 2006 Wiley Periodicals, Inc.

Coating of the orthopaedic titanium alloys with sol-gel derived hydroxyapatite

International Nuclear Information System (INIS)

Milev, A.; Green, D.; Chai, C.S.; Ben-Nissan, B.

1999-01-01

Hydroxyapatite (HAp) is known to be both biocompatible and bioactive material, however, due to its poor mechanical properties and design limitations is not suitable for applying as a load bearing implant. This could be overcome by using appropriate metallic substrates covered with HAp, derived via different techniques. These coatings allow improved adhesion strength of the load bearing substrate to the bone, resulting in shorter healing periods as well as predictable behaviour of the implant for longer periods of time. There are different techniques of producing HAp appropriate for coating purposes. Due to the small particle size of the grains derived, sol-gel route is preferable where lower sintering temperatures are of primary importance. For better adhesion between substrate and hydroxyapatite coating, the surface of titanium substrate, in this study, was converted to titanium nitride and/or oxynitride. Sintering temperatures of 900 deg C have been used for producing crystalline HAp coatings. The control of sol-gel solutions and the analysis of the coatings were carried out using XRD, SEM and DTA techniques. Results obtained indicate high quality HAp coatings can be produced on titanium substrates especially with complex shapes that benefits over the other coating methods

Sol-gel derived C-SiC composites and protective coatings for sustained durability in the space environment

Science.gov (United States)

Haruvy, Yair; Liedtke, Volker

2003-09-01

Composites and coatings were produced via the fast sol-gel process of a mixture of alkoxysilane precursors. The composites were comprised of carbon fibers, fabrics, or their precursors as reinforcement, and sol-gel-derived silicon carbide as matrix, aiming at high-temperature stable ceramics that can be utilized for re-entry structures. The protective coatings were comprised of fluorine-rich sol-gel derived resins, which exhibit high flexibility and coherence to provide sustained ATOX protection necessary for LEO space-exposed elements. For producing the composites, the sol-gel-derived resin is cast onto the reinforcement fibers/fabrics mat (carbon or its precursors) to produce a 'green' composite that is being cured. The 'green' composite is converted into a C-SiC composite via a gradual heat-pressure process under inert atmosphere, during which the organic substituents on the silicon atoms undergo internal oxidative pyrolysis via the schematic reaction: (SiRO3/2)n -> SiC + CO2 + H2O. The composition of the resultant silicon-oxi-carbide is tailorable via modifying the composition of the sol-gel reactants. The reinforcement, when made of carbon precursors, is converted into carbon during the heat-and-pressure processing as well. The C-SiC composites thus derived exhibit superior thermal stability and comparable thermal conductivity, combined with good mechanical strength features and failure resistance, which render them greatly applicable for re-entry shielding, heat-exchange pipes, and the like. Fluorine rich sol-gel derived coatings were developed as well, via the use of HF rich sol-gel process. These coatings provide oxidation-protection via the silica formation process, together with flexibility that allows 18,000 repetitive folding of the coating without cracking.

Luminescence of Eu(3+) doped SiO2 Thin Films and Glass Prepared by Sol-gel Technology

Science.gov (United States)

Castro, Lymari; Jia, Weiyi; Wang, Yanyun; Santiago, Miguel; Liu, Huimin

1998-01-01

Trivalent europium ions are an important luminophore for lighting and display. The emission of (5)D0 to (7)F2 transition exhibits a red color at about 610 nm, which is very attractive and fulfills the requirement for most red-emitting phosphors including lamp and cathode ray phosphorescence materials. Various EU(3+) doped phosphors have been developed, and luminescence properties have been extensively studied. On the other hand, sol-gel technology has been well developed by chemists. In recent years, applications of this technology to optical materials have drawn a great attention. Sol-gel technology provides a unique way to obtain homogeneous composition distribution and uniform doping, and the processing temperature can be very low. In this work, EU(3+) doped SiO2 thin films and glasses were prepared by sol-gel technology and their spectroscopic properties were investigated.

Sol-gel prepared active ternary oxide coating on titanium in cathodic protection

Directory of Open Access Journals (Sweden)

VLADIMIR V. PANIC

2007-12-01

Full Text Available The characteristics of a ternary oxide coating, on titanium, which consisted of TiO2, RuO2 and IrO2 in the molar ratio 0.6:0.3:0.1, calculated on the metal atom, were investigated for potential application for cathodic protection in a seawater environment. The oxide coatings on titanium were prepared by the sol gel procedure from a mixture of inorganic oxide sols, which were obtained by forced hydrolysis of metal chlorides. The morphology of the coating was examined by scanning electron microscopy. The electrochemical properties of activated titanium anodes were investigated by cyclic voltammetry and polarization measurements in a H2SO4- and NaCl-containing electrolyte, as well as in seawater sampled on the Adriatic coast in Tivat, Montenegro. The anode stability during operation in seawater was investigated by the galvanostatic accelerated corrosion stability test. The morphology and electrochemical characteristics of the ternary coating are compared to that of a sol-gel-prepared binary Ti0.6Ru0.4O2 coating. The activity of the ternary coating was similar to that of the binary Ti0.6Ru0.4O2 coating in the investigated solutions. However, the corrosion stability in seawater is found to be considerably greater for the ternary coating.

Study of Different Sol-Gel Coatings to Enhance the Lifetime of PDMS Devices: Evaluation of Their Biocompatibility.

Science.gov (United States)

Aymerich, María; Gómez-Varela, Ana I; Álvarez, Ezequiel; Flores-Arias, María T

2016-08-25

A study of PDMS (polydimethylsiloxane) sol-gel-coated channels fabricated using soft lithography and a laser direct writing technique is presented. PDMS is a biocompatible material that presents a high versatility to reproduce several structures. It is widely employed in the fabrication of preclinical devices due to its advantages but it presents a rapid chemical deterioration to organic solvents. The use of sol-gel layers to cover the PDMS overcomes this problem since it provides the robustness of glass for the structures made with PDMS, decreasing its deterioration and changing the biocompatibility of the surface. In this work, PDMS channels are coated with three different kinds of sol-gel compositions (60MTES/40TEOS, 70MTES/30TISP and 80MTES/20TISP). The endothelial cell adhesion to the different coated devices is evaluated in order to determine the most suitable sol-gel preparation conditions to enhance cellular adhesion.

Optical spectroscopy of arsenic- and silver-containing sol-gel coatings

Energy Technology Data Exchange (ETDEWEB)

Garcia, M.A.; Paje, S.E.; Llopis, J. [Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Madrid (Spain); Villegas, M.A.; Fernandez Navarro, J.M. [Departamento de Vidrios, Instituto de Ceramica y Vidrio, Madrid (Spain)

1999-05-07

Sol-gel silica coatings doped with 1 mol% silver and/or 1 mol% arsenic oxide have been investigated by photoluminescence (PL) and optical absorption (OA) spectroscopy. The presence of Ag{sup +} ions in the silica host has been monitored by recording a luminescence peak located between 320 and 330 nm upon excitation with 228 nm light, whereas the formation of small particles of metallic silver has been assessed by recording the absorption band centred at about 405 nm. The luminescence peak has been related to the d{sup 10} 10 {r_reversible} d{sup 9} s parity-forbidden transitions in Ag{sup +}, which are partially allowed by odd-phonon assistance. On the other hand, the absorption peak at about 405 nm arises from the well known surface-plasmon resonance of silver particles. Coating densification under various atmospheres gives rise to significant effects on the PL and OA spectra. Results indicate that, after coating densification in air, most of the silver appears as Ag{sup +} ions, in contrast to coating densification under a 90% N{sub 2}-10% H{sub 2} atmosphere, which favours the formation of small particles of metallic silver. The presence of arsenic oxide in the silver coatings densified in air has been found to improve the stabilization of Ag{sup +} ions, so that partially prevents the formation of colloidal silver under reducing atmospheres. (author)

Sol-gel coatings of ceramic fibres for composites with ceramic matrix

International Nuclear Information System (INIS)

Maier, B.; Grathwohl, G.; Spallek, M.; Pannhorst, W.

1992-01-01

The aim of this work was to show the feasibility in principle of sol-gel coating of ceramic reinforcement components for composites from technical aspects as well. The complexity of the coating task rises with the transition from individual fibres to bundles of fibres of different thickness to weaves, and finally to composites. (orig.) [de

Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology

Energy Technology Data Exchange (ETDEWEB)

Shiquan Tao

2006-12-31

The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of

Method of making ionic liquid mediated sol-gel sorbents

Science.gov (United States)

Malik, Abdul; Shearrow, Anne M.

2017-01-31

Ionic liquid (IL)-mediated sol-gel hybrid organic-inorganic materials present enormous potential for effective use in analytical microextraction. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol-gel reactions. A method was developed which provides phosphonium-based, pyridinium-based, and imidazolium-based IL-mediated advanced sol-gel organic-inorganic hybrid materials for capillary microextraction. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol-gel reactions. IL-mediated sol-gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions compared to analogous sol-gel coatings prepared without any IL in the sol solution. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol-gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol-gel material to be able to provide the desired sorbent characteristics.

Structural and optical studies of nano-structure silica gel doped with different rare earth elements, prepared by two different sol -gel techniques

International Nuclear Information System (INIS)

Battisha, I.K.; El Beyally, A.; Seliman, S.I.; El Nahrawi, A.S.

2005-01-01

Structural and optical characteristics of pure silica gel (silica-xerogel, SiO 2 ) and doped with different concentrations ranging from 1 up to 6% of some rare earth (REEs) ions such as, praseodymium Pr +3 ,and Europium Eu +3 , Erbium Er +3 and Holmium Ho +3 , ions, in the form of thin film and monolith materials were prepared by sol - gel technique, Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications. Some structural and optical features of sol-gel derived monolith and thin films are analyzed and compared, namely the structure of nano-particle monolith and thin film silica-gel samples, based on X-ray diffraction (XRD). The types of structural information obtainable are compared in detail. It is show that the XRD spectra of a-cristobalite are obtained for the two type materials and even by doping with the four REEs ions. Optical measurements of monolith and thin films were also studied and compared, the normal transmission and specular reflection were measured. The refractive index were calculated and discussed

Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

Science.gov (United States)

Panitz, Janda K.; Reed, Scott T.; Ashley, Carol S.; Neiser, Richard A.; Moffatt, William C.

1999-01-01

Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties.

Fundamental electrochemiluminescence characteristics of fluorine-doped tin oxides synthesized by sol-gel combustion.

Science.gov (United States)

Moon, B H; Chaoumead, A; Sung, Y M

2013-10-01

Fluorine-doped tin oxide (FTO) materials synthesized by sol-gel combustion method were investigated for electrochemical luminescence (ECL) application. Effects of sol-gel combustion conditions on the structures and morphology of the porous FTO (p-FTO) materials were studied. ECL efficiency of p-FTO-based cell was about 251 cd/m2 at 4 V bias, which is higher than the sell using only FTO electrodes (102.8 cd/m2). The highest intensity of the emitting light was obtained at the wavelength of about 610 nm. The porous FTO layer was effective for increasing ECL intensities.

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

Science.gov (United States)

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

2011-02-21

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

Low- and high-index sol-gel films for planar and channel-doped waveguides

Science.gov (United States)

Canva, Michael; Chaput, Frederic; Lahlil, Khalid; Rachet, Vincent; Goudket, Helene; Boilot, Jean-Pierre; Levy, Yves

2001-11-01

In view of realizing integrated optic components based on effects such as electro-optic, chi(2):chi(2) cascading, stimulated emission,... one has to first synthesize materials with the proper functionality; this may be achieved by doping solid state matrices by the appropriate organic chromophores. Second, and as important, these materials have to be properly structured into the final optical guiding structures. We shall report on issues related to the realization of chromophore-doped planar waveguides as well as channel waveguides. These structures were realized by either photo-transformation such as photo- chromism and photo-bleaching or reactive ion etching technique, starting with chromophore doped sol-gel materials at high loading contents for which optical index may be controlled via the local dopant concentration. With these materials and techniques, waveguides and components characterized by propagation losses of the order of a cm-1, measured off the edge of the absorption band of the doping species, were fabricated. In order to be also able to study and use waveguide functionalized with low concentration of chromophore species, we developed new sol-gel materials of high optical index, yet low temperature processed. These new films are under study to evaluate their potential as host for organic doped waveguides devices.

Effect of both deposition temperature and indium doping on the properties of sol-gel dip-coated SnO2 films.

Science.gov (United States)

Caglar, Mujdat; Atar, Kadir Cemil

2012-10-01

Using indium chloride as an In source, In-doped SnO(2) films were fabricated by sol-gel method through dip-coating on borofloat glass substrates. The undoped SnO(2) films were deposited in air between 400 and 600 °C to get optimum deposition temperature in terms of crystal quality and hence In-doped SnO(2) films were deposited in air at 600 °C. The effect of both deposition temperature and In content on structural, morphological, optical and electrical properties was investigated. The crystalline structure and orientation of the films were investigated by X-ray diffraction (XRD) and surface morphology was studied by a field emission scanning electron microscope (FESEM). The compositional analysis of the films was confirmed by energy dispersive X-ray spectrometer (EDS). The absorption band edge of the SnO(2) films shifted from 3.88 to 3.66 eV with In content. The van der Pauw method was used to measure the sheet resistance of the films. The sheet resistance was affected significantly by deposition temperature and In content. Copyright © 2012 Elsevier B.V. All rights reserved.

Sol-gel growth of vanadium dioxide

International Nuclear Information System (INIS)

Speck, K.R.

1990-01-01

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

Biocompatibility of sol-gel hydroxyapatite-titania composite and bilayer coatings

Energy Technology Data Exchange (ETDEWEB)

Sidane, D., E-mail: dj.sidane@yahoo.fr [Laboratoire de Génie de l' Environnement (LGE), Faculté de Technologie, Université de Bejaia, 06000, Bejaia (Algeria); Rammal, H. [Equipe d' Accueil 4691 Biomatériaux et Inflammation en Site Osseux, SFR-CAP Santé (FED 4231), Université de Reims Champagne Ardenne, 1 Avenue du Maréchal Juin, 51100 Reims (France); Beljebbar, A. [UMR CNRS 7369, Equipe MéDIAN Biophotonique et Technologies pour la Santé, UFR de Pharmacie, SFR-CAP Santé (FED 4231), Université de Reims Champagne Ardenne, 51 rue Cognacq-Jay, 51096 Reims (France); Gangloff, S.C. [Equipe d' Accueil 4691 Biomatériaux et Inflammation en Site Osseux, SFR-CAP Santé (FED 4231), Université de Reims Champagne Ardenne, 1 Avenue du Maréchal Juin, 51100 Reims (France); Chicot, D. [FRE 3723 - LML - Laboratoire de Mécanique de Lille, Univ. Lille, 59000 Lille (France); Velard, F. [Equipe d' Accueil 4691 Biomatériaux et Inflammation en Site Osseux, SFR-CAP Santé (FED 4231), Université de Reims Champagne Ardenne, 1 Avenue du Maréchal Juin, 51100 Reims (France); Khireddine, H. [Laboratoire de Génie de l' Environnement (LGE), Faculté de Technologie, Université de Bejaia, 06000, Bejaia (Algeria); and others

2017-03-01

Titania-Hydroxyapatite (TiO{sub 2}/HAP) reinforced coatings are proposed to enhance the bioactivity and corrosion resistance of 316L stainless steel (316L SS). Herein, spin- and dip-coating sol-gel processes were investigated to construct two kinds of coatings: TiO{sub 2}/HAP composite and TiO{sub 2}/HAP bilayer. Physicochemical characterization highlighted the bioactivity response of the TiO{sub 2}/HAP composite once incubated in physiological conditions for 7 days whereas the TiO{sub 2}/HAP bilayer showed instability and dissolution. Biological analysis revealed a failure in human stem cells adhesion on TiO{sub 2}/HAP bilayer whereas on TiO{sub 2}/HAP composite the presence of polygonal shaped cells, possessing good behaviour attested a good biocompatibility of the composite coating. Finally, TiO{sub 2}/HAP composite with hardness up to 0.6 GPa and elastic modulus up to 18 GPa, showed an increased corrosion resistance of 316L SS. In conclusion, the user-friendly sol-gel processes led to bioactive TiO{sub 2}/HAP composite buildup suitable for biomedical applications. - Highlights: • 316L SS implant TiO{sub 2} reinforced HAP coatings were investigated and compared. • TiO{sub 2}/HAP composite had better structural features and biocompatible properties. • Improvement of 316L SS implants corrosion resistance. • TiO{sub 2}/HAP composite mechanical properties close to bone tissue • Low cost and desired material for hard tissue applications.

Biocompatibility of sol-gel hydroxyapatite-titania composite and bilayer coatings

International Nuclear Information System (INIS)

Sidane, D.; Rammal, H.; Beljebbar, A.; Gangloff, S.C.; Chicot, D.; Velard, F.; Khireddine, H.

2017-01-01

Titania-Hydroxyapatite (TiO 2 /HAP) reinforced coatings are proposed to enhance the bioactivity and corrosion resistance of 316L stainless steel (316L SS). Herein, spin- and dip-coating sol-gel processes were investigated to construct two kinds of coatings: TiO 2 /HAP composite and TiO 2 /HAP bilayer. Physicochemical characterization highlighted the bioactivity response of the TiO 2 /HAP composite once incubated in physiological conditions for 7 days whereas the TiO 2 /HAP bilayer showed instability and dissolution. Biological analysis revealed a failure in human stem cells adhesion on TiO 2 /HAP bilayer whereas on TiO 2 /HAP composite the presence of polygonal shaped cells, possessing good behaviour attested a good biocompatibility of the composite coating. Finally, TiO 2 /HAP composite with hardness up to 0.6 GPa and elastic modulus up to 18 GPa, showed an increased corrosion resistance of 316L SS. In conclusion, the user-friendly sol-gel processes led to bioactive TiO 2 /HAP composite buildup suitable for biomedical applications. - Highlights: • 316L SS implant TiO 2 reinforced HAP coatings were investigated and compared. • TiO 2 /HAP composite had better structural features and biocompatible properties. • Improvement of 316L SS implants corrosion resistance. • TiO 2 /HAP composite mechanical properties close to bone tissue • Low cost and desired material for hard tissue applications

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

Science.gov (United States)

Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

2014-12-01

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

Up-conversion luminescence application in Er3+: TiO2 thin film prepared by dip coating sol-gel route

International Nuclear Information System (INIS)

Badr, Y.; Battisha, I.K.; Salah, A.; Salem, M.A.

2008-01-01

Sol-gel derived nano-crystalline titanium dioxide films doped with 1 up to 5% Er 3+ ions were prepared by dip coating sol-gel method. The coating sol was obtained by hydrolysis of Ti(OC 4 H 9 ) 4 in ethanol/HCI solution. The FT-Raman and the X-ray diffraction (XRD) were carried out to determine the crystal structure of the prepared samples. The morphology SEM and the cross-sectional of the film were used to characterize the microstructure and the thickness of the prepared film. It is shown that relative homogeneous, crack-free and transparent film was achieved via dipping process at 500 deg C. After the excitation with laser diode at wavelength 808 nm, visible (Vis) and infrared (IR) up-conversion emissions were evidenced in the thin film samples under investigation. The up-conversion was found to depend strongly on the Er 3+ ion concentrations. The visible emission was found to be at 540, 560, 590 and 640 nm for thin film. They are attributed to intra-4f transition of Er 3+ ions and assigned to the ( 2 H 11/2 + 4 S 3/2 ) and 4 F 9/2 , which are populated through excited state absorption (ESA) for 808 nm excitation. (author)

Synthesis and characterization of erbium-doped SiO{sub 2}-TiO{sub 2} thin films prepared by sol-gel and dip-coating techniques onto commercial glass substrates as a route for obtaining active GRadient-INdex materials

Energy Technology Data Exchange (ETDEWEB)

Gómez-Varela, Ana I. [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain); Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, Madrid 28049 (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, Madrid 28049 (Spain); De Beule, Pieter A.A. [Applied Nano-Optics Laboratory, International Iberian Nanotechnology Laboratory, Braga 4715-330 (Portugal); Flores-Arias, María T. [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain); Bao-Varela, Carmen, E-mail: carmen.bao@usc.es [Microoptics and GRIN Optics Group, Department of Applied Physics, Faculty of Optics and Optometry and Faculty of Physics, Universidade de Santiago de Compostela, Campus Vida s/n, Santiago de Compostela E-15782 (Spain)

2015-05-29

In this work, SiO{sub 2}-TiO{sub 2} films doped with erbium were prepared by dip-coating sol-gel process onto commercial glass substrates. The surface morphology of the films was characterized using atomic force microscopy, while thickness, refractive index, extinction coefficient and porosity of the films were determined by ellipsometric measurements in a wavelength region of 400-1000 nm. Optical constants and porosity were found to vary with erbium concentration. The proof of principle presented in this paper is applicable to systems of different nature by tailoring the sol-gel precursors in such a way that active GRadient-INdex media described by a complex, parabolic-like refractive index distribution for beam shaping purposes is obtained. - Highlights: • Sol-gel route for preparation of active GRadient-INdex materials is proposed. • SiO{sub 2}-TiO{sub 2} films doped with erbium were prepared by dipping onto commercial glasses. • Morphological and optical characterization of the samples was performed. • Optical constants and porosity were found to vary with erbium concentration. • Refractive index diminishes with dopant content; the contrary occurs for porosity.

Cu-Doped ZnO Thin Films Deposited by a Sol-Gel Process Using Two Copper Precursors: Gas-Sensing Performance in a Propane Atmosphere

Directory of Open Access Journals (Sweden)

Heberto Gómez-Pozos

2016-01-01

Full Text Available A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM and secondary ion mass spectroscopy (SIMS, respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C3H8, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 104, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C3H8 gas.

Fabrication of yttrium-doped barium zirconate thin films with sub-micrometer thickness by a sol–gel spin coating method

Energy Technology Data Exchange (ETDEWEB)

Xie, Hanlin; Su, Pei-Chen, E-mail: peichensu@ntu.edu.sg

2015-06-01

A modified sol–gel process was developed for the fabrication of sub-micrometer scale yttrium-doped barium zirconate (BZY) thin film at much lower processing temperatures. The film was fabricated by direct spin-coating of the sol on a Si{sub 3}N{sub 4} passivated Si substrate, followed by low temperature thermal annealing at 1000 °C, and single BZY phase without barium carbonate residue was obtained. A 200 nm-thick thin film without obvious through-film cracks was fabricated with optimized process parameters of sol concentration and heating rate. The stoichiometry of the BZY thin film was well-controlled and no Ba evaporation was observed due to the low processing temperature. The combination of sol–gel and spin coating method can be a promising alternative to vacuum-based thin film deposition techniques for the fabrication of sub-micrometer scale BZY thin film. - Highlights: • A sol–gel spin coating method was developed for the fabrication of BZY thin films. • The processing temperature was much lower compared to powder-based sintering. • Sub-micrometer scale BZY thin film with well-controlled stoichiometry was obtained.

Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

Energy Technology Data Exchange (ETDEWEB)

Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

2010-07-01

Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

Sol-Gel Derived Hydroxyapatite Coating on Mg-3Zn Alloy for Orthopedic Application

Science.gov (United States)

Singh, Sanjay; Manoj Kumar, R.; Kuntal, Kishor Kumar; Gupta, Pallavi; Das, Snehashish; Jayaganthan, R.; Roy, Partha; Lahiri, Debrupa

2015-04-01

In recent years, magnesium and its alloys have gained a lot of interest as orthopedic implant constituents because their biodegradability and mechanical properties are closer to that of human bone. However, one major concern with Mg in orthopedics is its high corrosion rate that results in the reduction of mechanical integrity before healing the bone tissue. The current study evaluates the sol-gel-derived hydroxyapatite (HA) coating on a selected Mg alloy (Mg-3Zn) for decreasing the corrosion rate and increasing the bioactivity of the Mg surface. The mechanical integrity of the coating is established as a function of the surface roughness of the substrate and the sintering temperature of the coating. Coating on a substrate roughness of 15-20 nm and sintering at 400°C shows the mechanical properties in similar range of bone, thus making it suitable to avoid the stress-shielding effect. The hydroxyapatite coating on the Mg alloy surface also increases corrosion resistance very significantly by 40 times. Bone cells are also found proliferating better in the HA-coated surface. All these benefits together establish the candidature of sol-gel HA-coated Mg-3Zn alloy in orthopedic application.

Sol-gel/drop-coated micro-thick TiO{sub 2} memristors for γ-ray sensing

Energy Technology Data Exchange (ETDEWEB)

Abunahla, Heba [Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); Jaoude, Maguy Abi, E-mail: maguy.abijaoude@kustar.ac.ae [Department of Applied Mathematics and Sciences, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); O' Kelly, Curtis J.; Mohammad, Baker [Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates)

2016-12-01

Sol-gel/drop-coated micro-thick TiO{sub 2} memristors were investigated and developed for low-power radiation sensing. Devices constructed with coated aluminum (Al) electrodes exhibited unipolar I-V characteristics with dynamic turn-on voltage, and progressive R{sub OFF}/R{sub ON} ratio loss under applied bias. Endurance failure of micro-thick Al/Al stacks is ascribed to gradual passivation of Al surface resulting from an electrically-enhanced oxygen-ion diffusion. By exchanging a single Al contact with higher work function copper (Cu) metal, two distinct superimposed TiO{sub 2} phases were formed. The TiO{sub 2} coating on Al surface was carbon-contaminated and amorphous, while that on Cu was found to be additionally doped with Cu{sup (I/II)} ions resulting from the corrosion of the surface of the electrode by the amine-based gelation agent. After initial forming, the hybrid stack could achieve a bipolar memristance, with high R{sub OFF}/R{sub ON} (up to 10{sup 6}), and over 10 switching cycles at low-operating voltages (±1 V). The enhanced memristive switching properties of Al/Cu devices are explained via cooperative valence-change/electrochemical-metallization processes, involving migration of oxygen and copper species. The advanced micro-thick TiO{sub 2} memristors were exposed to Cs-137 γ-rays, providing for the first time initial insights into their radiation detection capabilities. The sensing mechanism through these devices could be actuated by synergistic radiation-induced and field-driven photo-electric effects. - Highlights: • Micro-thick TiO{sub 2} memristors with Al or Cu electrodes are advanced via sol-gel drop-coating. • Memristive switching in Al/TiO{sub 2}/Al structure is not viable due to resistance build-up. • Drop-coated Cu electrode gets corroded by ethanolamine additive, introducing Cu{sup (I/II)} cations into bulk TiO{sub 2}. • Bipolar memristance in Al/TiO{sub 2}/Cu{sup (I/II)} doped-TiO{sub 2}/Cu structure is depicted for the

Silica- and germania-based dual-ligand sol-gel organic-inorganic hybrid sorbents combining superhydrophobicity and π-π interaction. The role of inorganic substrate in sol-gel capillary microextraction.

Science.gov (United States)

Seyyal, Emre; Malik, Abdul

2017-04-29

Principles of sol-gel chemistry were utilized to create silica- and germania-based dual-ligand surface-bonded sol-gel coatings providing enhanced performance in capillary microextraction (CME) through a combination of ligand superhydrophobicity and π-π interaction. These organic-inorganic hybrid coatings were prepared using sol-gel precursors with bonded perfluorododecyl (PF-C 12 ) and phenethyl (PhE) ligands. Here, the ability of the PF-C 12 ligand to provide enhanced hydrophobic interaction was advantageously combined with π-π interaction capability of the PhE moiety to attain the desired sorbent performance in CME. The effect of the inorganic sorbent component on microextraction performance of was explored by comparing microextraction characteristics of silica- and germania-based sol-gel sorbents. The germania-based dual-ligand sol-gel sorbent demonstrated superior CME performance compared to its silica-based counterpart. Thermogravimetric analysis (TGA) of the created silica- and germania-based dual-ligand sol-gel sorbents suggested higher carbon loading on the germania-based sorbent. This might be indicative of more effective condensation of the organic ligand-bearing sol-gel-active chemical species to the germania-based sol-gel network (than to its silica-based counterpart) evolving in the sol solution. The type and concentration of the organic ligands were varied in the sol-gel sorbents to fine-tune extraction selectivity toward different classes of analytes. Specific extraction (SE) values were used for an objective comparison of the prepared sol-gel CME sorbents. The sorbents with higher content of PF-C 12 showed remarkable affinity for aliphatic hydrocarbons. Compared to their single-ligand sol-gel counterparts, the dual-ligand sol-gel coatings demonstrated significantly superior CME performance in the extraction of alkylbenzenes, providing up to ∼65.0% higher SE values. The prepared sol-gel CME coatings provided low ng L -1 limit of detections (LOD

Repair of glass by sol-gel coating using either conventional or microwave heating

International Nuclear Information System (INIS)

Boonyapiwat, A.; Fathi, Z.; Folz, D.C.; Clark, D.E.

1993-01-01

A method of repairing glass is discussed. Microindentation was used to deliberately weaken the glass. Some samples were dip coated with silica sol. Effects of dipping the glass in copper nitrate solution also were studied. Heat treatments were conducted in either a conventional furnace or a microwave oven. Four-point bend testing was used to evaluate the merit of each process. Microwave hybrid heating had the same effect on the repair of uncoated glass as conventional heating. Coating the glass with sol resulted in higher strength of glass than heat treatment alone. Treating the glass with copper nitrate without heat treating had no effect on strength. Microwave hybrid heating appears to yield higher reliability in sol-gel coated samples than conventional processing. 21 refs., 8 figs., 2 tabs

Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

Science.gov (United States)

Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

2006-05-02

An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

Bioactive materials for biomedical applications using sol-gel technology

International Nuclear Information System (INIS)

Gupta, Radha; Kumar, Ashok

2008-01-01

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

Magnetic properties of sol-gel synthesized C-doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dung, Nguyen Duc, E-mail: dung.nguyenduc@hust.edu.vn [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Son, Cao Thai; Loc, Pham Vu; Cuong, Nguyen Huu; Kien, Pham The; Huy, Pham Thanh [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam)

2016-05-25

ZnO doping with Carbon (C-doped ZnO) materials were prepared by sol-gel technique following with a heat treatment process. Single phase of Wurtzite crystal structure of ZnO was concluded via x-ray diffraction (XRD) with a large amount of excess C tracking by energy dispersive X-ray spectroscopy (EDX) analysis. Two types of ZnO crystals (twinning particles) with different grain sizes and shapes were identified via scanning electron microscopy (FE-SEM). The first type has a smaller grain size of about 20 nm and hexagonal shape. And the second type has a larger grain size of about 80–120 nm and round shape. C substitutions of both Zn and O sites to form C–O and C–Zn bonds were conclusively confirmed via x-ray photoelectron spectroscope (XPS). Experimental evidences for the co-existence of different ferromagnetic phases in the materials are reported and discussed. Two Curie points at high temperatures (>500 °C) are presented. A metamagnetic transition was observed at magnetic field H = 19.2 kOe which was related to the co-existence of ferromagnetic phases. These involve in the formation of twinning C-doped ZnO nanoparticles. - Highlights: • Formation of sol-gel prepared single phase wurtzite ZnO nanoparticles. • Two morphological C-doped ZnO nanoparticles of different grain sizes. • The room temperature ferromagnetism. • An abnormal metamagnetic transition at magnetic field H = 19.2 kOe. • Two different Curie points (T{sub C}) at 500–600 °C.

Improved electrochromical properties of sol-gel WO3 thin films by doping gold nanocrystals

International Nuclear Information System (INIS)

Naseri, N.; Azimirad, R.; Akhavan, O.; Moshfegh, A.Z.

2010-01-01

In this investigation, the effect of gold nanocrystals on the electrochromical properties of sol-gel Au doped WO 3 thin films has been studied. The Au-WO 3 thin films were dip-coated on both glass and indium tin oxide coated conducting glass substrates with various gold concentrations of 0, 3.2 and 6.4 mol%. Optical properties of the samples were studied by UV-visible spectrophotometry in a range of 300-1100 nm. The optical density spectra of the films showed the formation of gold nanoparticles in the films. The optical bandgap energy of Au-WO 3 films decreased with increasing the Au concentration. Crystalline structure of the doped films was investigated by X-ray diffractometry, which indicated formation of gold nanocrystals in amorphous WO 3 thin films. X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of the samples. XPS analysis indicated the presence of gold in metallic state and the formation of stoichiometric WO 3 . The electrochromic properties of the Au-WO 3 samples were also characterized using lithium-based electrolyte. It was found that doping of Au nanocrystals in WO 3 thin films improved the coloration time of the layer. In addition, it was shown that variation of Au concentration led to color change in the colored state of the Au-WO 3 thin films.

Sol-gel coatings: An alternative route for producing planar optical waveguides

Energy Technology Data Exchange (ETDEWEB)

Rey-Garcia, F.; Gomez-Reino, C. [Unidad Asociada de Optica and Microoptica GRIN (CSIC-ICMA), Departamento de Fisica Aplicada, Escola Universitaria de Optica e Optometria, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela (Spain); Flores-Arias, M.T., E-mail: maite.flores@usc.es [Unidad Asociada de Optica and Microoptica GRIN (CSIC-ICMA), Departamento de Fisica Aplicada, Escola Universitaria de Optica e Optometria, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela (Spain); De La Fuente, G.F., E-mail: xerman@unizar.es [Instituto de Ciencia de Materiales de Aragon (CSIC-Universidad de Zaragoza), Maria de Luna 3, E-50018 Zaragoza (Spain); Duran, A. [Instituto de Ceramica y Vidrio (CSIC), Kelsen 5, E-28049, Madrid (Spain); Castro, Y., E-mail: castro@icv.csic.es [Instituto de Ceramica y Vidrio (CSIC), Kelsen 5, E-28049, Madrid (Spain)

2011-09-01

Inorganic and hybrid planar waveguides with different compositions (silica-titania, methacrylate-silica-cerium oxide, zirconia-cerium oxide and silica-zirconia) have been obtained by sol-gel synthesis followed by dip-coating. Soda-lime glass slides and conventional commercial window glass were used as substrates. The thickness and refractive index of the coatings were determined by profilometry and Spectroscopic Ellipsometry. Waveguide efficiency was measured at ca. 70.8% with a He-Ne laser beam, coupled with an optical microscope objective into and out of the waveguiding layer via a double prism configuration. Thicknesses between 150 and 2000 nm, along with refractive index values ranging between 1.45 and {approx} 1.99 ({lambda} = 633 nm) were obtained depending on the sol composition and the dip-coating conditions. This wide range of values allows designing multilayered guides that can be used in a variety of applications.

Sol-gel coatings: An alternative route for producing planar optical waveguides

International Nuclear Information System (INIS)

Rey-Garcia, F.; Gomez-Reino, C.; Flores-Arias, M.T.; De La Fuente, G.F.; Duran, A.; Castro, Y.

2011-01-01

Inorganic and hybrid planar waveguides with different compositions (silica-titania, methacrylate-silica-cerium oxide, zirconia-cerium oxide and silica-zirconia) have been obtained by sol-gel synthesis followed by dip-coating. Soda-lime glass slides and conventional commercial window glass were used as substrates. The thickness and refractive index of the coatings were determined by profilometry and Spectroscopic Ellipsometry. Waveguide efficiency was measured at ca. 70.8% with a He-Ne laser beam, coupled with an optical microscope objective into and out of the waveguiding layer via a double prism configuration. Thicknesses between 150 and 2000 nm, along with refractive index values ranging between 1.45 and ∼ 1.99 (λ = 633 nm) were obtained depending on the sol composition and the dip-coating conditions. This wide range of values allows designing multilayered guides that can be used in a variety of applications.

Methylene blue degradation by NaTaO3 sol-gel doped with Sm and La

International Nuclear Information System (INIS)

Torres-Martinez, Leticia M.; Cruz-Lopez, Arquimedes; Juarez-Ramirez, Isaias; Meza-de la Rosa, Ma. Elena

2009-01-01

In this work, NaTaO 3 compounds doped with 1 M% of La and Sm, were prepared by the sol-gel (SG) method and solid state (SS) reaction; and tested as photocatalysts on the degradation of methylene blue (MB) under UV light. The structural characterization by X-ray powder diffraction revealed that the crystallization of the NaTaO 3 phase prepared by the sol-gel method started at 600 deg. C, reaching maximum crystallization at 800 deg. C. It was determined that the presence of Sm and La retard the crystallization of the NaTaO 3 phase. On the other hand, the compounds synthesized in this work showed particle sizes in the nanometric scale, as it was observed by scanning electron microscopy (SEM). The specific surface area of the compounds synthesized by the sol-gel method, showed values 4 times higher than those obtained by the solid state reaction, favoring their functional and photocatalytic performance in the methylene blue degradation. In addition, the best photocatalytic performance was shown by the NaTaO 3 doped with Sm and heated at 600 deg. C, having a half-life time of 65 min.

COMPARISON OF SOL-GEL SILICATE COATINGS ON Ti SUBSTRATE

Directory of Open Access Journals (Sweden)

DIANA HORKAVCOVÁ

2012-12-01

Full Text Available The objective of the submitted work was to prepare and to characterize two types of silicate coatings prepared by the sol-gel method using the dip-coating technique on a titanium substrate. Efforts have been made to use mechanical properties of bio-inert titanium and bioactive properties of a silicate layer enriched with an admixture of compounds identified below. The first group consisted of silicate coatings containing silver, brushite and monetite. The other group of silicate coatings contained calcium nitrate and triethyl phosphate. Mechanically and chemically treated titanium substrates were dipped into sols and dried and fired. Silicate coatings from the first group were also chemically treated in 10 mol.l-1 solution of sodium hydroxide. All coatings were measured to determine their adhesive and bioactive properties and furthermore the antibacterial properties were tested in the case of first group. Surfaces of the coated substrates were investigated after the firing and after the individual tests with optical and electron microscopy and X-ray microdiffraction. A tape test demonstrated excellent adhesive property of all coatings to the substrate, classified with degree 5. A static in vitro test demonstrated bioactivity of nearly all the coatings. The basic silicate coating from the first group and one type of coating from the second group were identified as inert. Antibacterial properties of silicate coatings containing silver showed to be different when tested against Escherichia coli bacteria. A complete inhibition of the growth of bacteria under our experimental conditions was observed for the coating containing silver and monetite and a partial inhibition of the growth of bacteria for coatings containing silver and silver in combination with brushite.

Bactericidal micron-thin sol-gel films prevent pin tract and periprosthetic infection.

Science.gov (United States)

Qu, Haibo; Knabe, Christine; Burke, Megan; Radin, Shula; Garino, Jonathan; Schaer, Thomas; Ducheyne, Paul

2014-08-01

Orthopedic injuries constitute the majority of wounds sustained by U.S. soldiers in recent conflicts. The risk of infection is considerable with fracture fixation devices. In this pilot study, we examined the use of unique bactericidal micron-thin sol-gel films on fracture fixation devices and their ability to prevent and eradicate infections. External fixation was studied with micron-thin sol-gel coated percutaneous pins releasing triclosan and inserted medially into rabbit tibiae. A total of 11 rabbits received percutaneous pins that were either uncoated or sol-gel/triclosan coated. Internal fracture fixation was also studied using sol-gel coated intramedullary (IM) nails releasing vancomycin in the intramedullary tibiae. Six sheep received IM nails that were coated with a sol-gel film that either contained vancomycin or did not contain vancomycin. All animals were challenged with Staphylococcus aureus around the implant. Animals were euthanized at 1 month postoperative. Rabbits receiving triclosan/sol-gel coated percutaneous pins did not show signs of infection. Uncoated percutaneous pins had a significantly higher infection rate. In the sheep study, there were no radiographic signs of osteomyelitis with vancomycin/sol-gel coated IM nails, in contrast to the observations in the control cohort. Hence, the nanostructured sol-gel controlled release technology offers the promise of a reliable and continuous delivery system of bactericidals from orthopedic devices to prevent and treat infection. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

Science.gov (United States)

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Radiation hardness of Ce-doped sol-gel silica fibers for high energy physics applications.

Science.gov (United States)

Cova, Francesca; Moretti, Federico; Fasoli, Mauro; Chiodini, Norberto; Pauwels, Kristof; Auffray, Etiennette; Lucchini, Marco Toliman; Baccaro, Stefania; Cemmi, Alessia; Bártová, Hana; Vedda, Anna

2018-02-15

The results of irradiation tests on Ce-doped sol-gel silica using x- and γ-rays up to 10 kGy are reported in order to investigate the radiation hardness of this material for high-energy physics applications. Sol-gel silica fibers with Ce concentrations of 0.0125 and 0.05 mol. % are characterized by means of optical absorption and attenuation length measurements before and after irradiation. The two different techniques give comparable results, evidencing the formation of a main broad radiation-induced absorption band, peaking at about 2.2 eV, related to radiation-induced color centers. The results are compared with those obtained on bulk silica. This study reveals that an improvement of the radiation hardness of Ce-doped silica fibers can be achieved by reducing Ce content inside the fiber core, paving the way for further material development.

Mechanical compatibility of sol-gel annealing with titanium for orthopaedic prostheses.

Science.gov (United States)

Greer, Andrew I M; Lim, Teoh S; Brydone, Alistair S; Gadegaard, Nikolaj

2016-01-01

Sol-gel processing is an attractive method for large-scale surface coating due to its facile and inexpensive preparation, even with the inclusion of precision nanotopographies. These are desirable traits for metal orthopaedic prostheses where ceramic coatings are known to be osteoinductive and the effects may be amplified through nanotexturing. However there are a few concerns associated with the application of sol-gel technology to orthopaedics. Primarily, the annealing stage required to transform the sol-gel into a ceramic may compromise the physical integrity of the underlying metal. Secondly, loose particles on medical implants can be carcinogenic and cause inflammation so the coating needs to be strongly bonded to the implant. These concerns are addressed in this paper. Titanium, the dominant material for orthopaedics at present, is examined before and after sol-gel processing for changes in hardness and flexural modulus. Wear resistance, bending and pull tests are also performed to evaluate the ceramic coating. The findings suggest that sol-gel coatings will be compatible with titanium implants for an optimum temperature of 500 °C.

Iron porphyrins doped sol-gel glasses: a chemometric study

International Nuclear Information System (INIS)

Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R.

2000-01-01

This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na) 4 Cl and Fe TCPP(Na) 4 Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established . The variables (Solvent volume, fractional factorial design in two levels, 2 5-1 type, generating 16 total experiments for each Fe P studied. (author)

Urea functionalized surface-bonded sol-gel coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

Science.gov (United States)

Jillani, Shehzada Muhammad Sajid; Alhooshani, Khalid

2018-03-30

Sol-gel urea functionalized-[bis(hydroxyethyl)amine] terminated polydimethylsiloxane coating was developed for capillary microextraction-high performance liquid chromatographic analysis from aqueous samples. A fused silica capillary is coated from the inside with surface bonded coating material and is created through in-situ sol-gel reaction. The urea-functionalized coating was immobilized to the inner surface of the capillary by the condensation reaction of silanol groups of capillary and sol-solution. The characterization of the coating material was successfully done by using X-ray photoelectron spectroscopy, thermogravimetric analysis, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. To make a setup of online capillary microextraction-high performance liquid chromatography, the urea functionalized capillary was installed in the HPLC manual injection port. The analytes of interest were pre-concentrated in the coated sampling loop, desorbed by the mobile phase, chromatographically separated on C-18 column, and analyzed by UV detector. Sol-gel coated capillaries were used for online extraction and high-performance liquid chromatographic analysis of phenols, ketones, aldehydes, and polyaromatic hydrocarbons. This newly developed coating showed excellent extraction for a variety of analytes ranging from highly polar to non-polar in nature. The analysis using sol-gel coating showed excellent overall sensitivity in terms of lower detection limits (S/N = 3) for the analytes (0.10 ng mL -1 -14.29 ng mL -1 ) with acceptable reproducibility that is less than 12.0%RSD (n = 3). Moreover, the capillary to capillary reproducibility of the analysis was also tested by changing the capillary of the same size. This provided excellent%RSD of less than 10.0% (n = 3). Copyright © 2018 Elsevier B.V. All rights reserved.

Characterisation of a new alkoxide sol-gel hydroxyapatite

International Nuclear Information System (INIS)

Green, D.D.; Kannangara, G.S.K.; Milev, A.; Ben-Nissan, B.

1999-01-01

Hydroxyapatite (HAp) coatings have been used to promote bone growth and fixation towards implant surfaces to encourage faster recovery times for the recipient. Current coating processing techniques, capable of producing thin HAp layers are pulsed-laser deposition and sputtering (high-temperature processing). Other technologies are in vitro methods, electrodeposition and sol-gel, due to the fact that these techniques utilise lower processing temperatures they avoid structural instabilities of HAp at elevated temperatures. The term sol-gel encompasses any process of producing ceramic materials (single and mixed oxides, as well as non-oxides e.g. nitrides) from solutions. The sol-gel process was first identified by Ebelman, and has been used to produce ceramic powders, coatings, and bulk materials including glasses. The implementation of a sol-gel methodology enables increased stoichiometry and homogeneity, while having the ability to coat complex shapes. Sol-gel hydroxyapatite reported by Chai et al. employed tri ethyl phosphite [ P(OEt) 3 ] as the staring phosphorus alkoxide precursor, whereby it was established that in order to obtain monophasic hydroxyapatite upon firing there must be a 24 hour ripening period. The ripening period was determined to be an equilibrium step whereby the equilibrium intermediate phase lied in favour of a diethyl phosphite arrangement (species) within the sol. Therefore, the work here under taken was to produce hydroxyapatite using diethyl phosphite [HOP(OEt) 2 ] as a starting alkoxide precursor with a final aim to reduce or eliminate the ageing period as observed by Chai et al in P(OEt) 3 solutions

Sol-gel encapsulation for controlled drug release and biosensing

Science.gov (United States)

Fang, Jonathan

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.

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

International Nuclear Information System (INIS)

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

2008-01-01

Nanocrystalline fluorite type samarium doped ceria (SDC) electrolyte thin film for intermediate temperature-solid oxide fuel cells (IT-SOFCs) application were prepared on the dense and porous substrates at low temperatures of 573-1373 K using a novel citrate sol-gel route combined with a sol suspension spray coating technique. Thermogravimetric analysis showed that the decomposition of the citrate gel film and the initial crystallization of the SDC occurred at a low temperature of about 590 K. XRD examination revealed that the annealing of the green film at temperatures of 573-1373 K provided cubic nanocrystalline SDC phase. The crystallite sizes were in the range of 9-19 nm. Microscopic observations indicated that the derived film was homogeneous, dense and crack-free without pinholes. The desired thickness for preparation of thin electrolyte films from hundreds of nm to several μm should be controllable and feasible by repeating the simple and inexpensive citrate sol-gel spray coating process

Effect of Chelating Agents on the Stability of Nano-TiO2 Sol Particles for Sol-Gel Coating.

Science.gov (United States)

Maeng, Wan Young; Yoo, Mi

2015-11-01

Agglomeration of sol particles in a titanium alkoxide (tetrabutyl orthotitanate (TBOT), > 97%) solution during the hydrolysis and condensation steps makes the sol solution difficult to use for synthesizing homogeneous sol-gel coating. Here, we have investigated the effect of stabilizing agents (acetic acid and ethyl acetoacetate (EAcAc)) on the agglomeration of Ti alkoxide particles during hydrolysis and condensation in order to determine the optimized conditions for controlling the precipitation of TiO2 particles. The study was conducted at R(AC) ([acetic acid]/[TBOT]) = 0.1-5 and R(EAcAc)([EAcAc]/[TBOT]) = 0.05-0.65. We also studied the effects of a basic catalyst ethanolamine (ETA), water, and HCl on sol stability. The chelating ligands in the precursor sol were analyzed with FT-IR. The coating properties were examined by focused ion beam. The stabilizing agents (acetic acid and EAcAc) significantly influenced the agglomeration and precipitation of TBOT precursor particles during hydrolysis. As R(AC) and R(EAcAc) increased, the agglomeration remarkably decreased. The stability of the sol with acetic acid and EAcAc arises from the coordination of the chelating ligand to TBOT that hinders hydrolysis and condensation. A uniform fine coating (thickness: 30 nm) on stainless steel was obtained by using an optimized sol with R(AC) = 0.5 and R(EAcAc) = 0.65.

Fluorescence yield in rare-earth-doped sol-gel silicate glasses

Energy Technology Data Exchange (ETDEWEB)

Silversmith, A.J., E-mail: asilvers@hamilton.ed [Physics Department, Hamilton College, 198 College Hill Road, Clinton, NY 13323 (United States); Nguyen, Nguyen T.T.; Campbell, D.L. [Physics Department, Hamilton College, 198 College Hill Road, Clinton, NY 13323 (United States); Boye, D.M.; Ortiz, C.P. [Davidson College, Davidson, NC 28035 (United States); Hoffman, K.R. [Whitman College, Walla Walla, WA 99362 (United States)

2009-12-15

We have used trivalent terbium to investigate the mechanism behind fluorescence enhancement by Al{sup 3+} co-doping. Our results indicate that rare-earth (RE) ions cluster together in aluminum-rich regions of the glass, and behave as if they were dispersed uniformly throughout these regions when the ratio of Al to RE is {approx}10 or greater. We also studied the effects of adding chemical drying agents to the precursor solution for the synthesis of sol-gel-derived silicate glasses. Such glasses can be treated at significantly higher annealing temperatures without degradation of optical quality, and have the density of melt glass. Fluorescence yield from doped RE ions improves markedly with the addition of the drying agents, and the denser glasses are not subject to rehydration.

Improving the scratch resistance of sol-gel metal oxide coatings cured at 250 C through use of thermogenerated amines

NARCIS (Netherlands)

Langanke, J.; Arfsten, N.; Buskens, P.; Habets, R.; Klankermayer, J.; Leitner, W.

2013-01-01

Scratch resistant sol-gel metal oxide coatings typically require a thermal post-treatment step (curing process) at temperatures between 400 and 700 C. In this report, we demonstrate that the in situ generation of amines within sol-gel films facilitates the preparation of scratch resistant metal

Modified silica sol coatings for surface enhancement of leather.

Science.gov (United States)

Mahltig, Boris; Vossebein, Lutz; Ehrmann, Andrea; Cheval, Nicolas; Fahmi, Amir

2012-06-01

The presented study reports on differently modified silica sols for coating applications on leather. Silica sols are prepared by acidic hydrolysis of tetraethoxysilane and modified by silane compounds with fluorinated and non-fluorinated alkylgroups. In contrast to many earlier investigations regarding sol-gel applications on leather, no acrylic resin is used together with the silica sols when applying on leather. The modified silica particles are supposed to aggregate after application, forming thus a modified silica coating on the leather substrate. Scanning electron microscopy investigation shows that the applied silica coatings do not fill up or close the pores of the leather substrate. However, even if the pores of the leather are not sealed by this sol-gel coating, an improvement of the water repellent and oil repellent properties of the leather substrates are observed. These improved properties of leather by application of modified silica sols can provide the opportunity to develop sol-gel products for leather materials present in daily life.

Effect of various lanthanum sol-gel coatings on the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C

Energy Technology Data Exchange (ETDEWEB)

Buscail, H., E-mail: buscail@iut.u-clermont1.fr [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Issartel, C.; Riffard, F.; Rolland, R.; Perrier, S. [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Fleurentin, A. [CETIM, 52 av Felix Louat, BP 80067, 60304 Senlis (France); Josse, C. [L' ICB UMR5209 CNRS, BP 47870, 21078 Dijon (France)

2011-11-01

The influence of a lanthanum sol-gel coating on the oxide scale adherence has been studied during the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C, in air. The alloy oxidation is performed in order to generate a protective chromia scale acting as a good barrier against carburization. Argon annealing of lanthanum sol-gel coatings have been performed at various temperatures in order to find the best conditions to insure the scale adherence. Kinetic results show that lanthanum sol-gel coatings lead to a lower oxidation rate compared to blank specimens. Thermal cycling tests on lanthanum the sol-gel coated specimen show that the oxide scale formed at 900 deg. C, in air, is adherent.

Bioactivity of sol-gel-derived TiO2 coating on polyetheretherketone: In vitro and in vivo studies.

Science.gov (United States)

Shimizu, Takayoshi; Fujibayashi, Shunsuke; Yamaguchi, Seiji; Yamamoto, Koji; Otsuki, Bungo; Takemoto, Mitsuru; Tsukanaka, Masako; Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Matsuda, Shuichi

2016-04-15

A polyetheretherketone (PEEK) surface was modified using a sol-gel-derived TiO2 coating in order to confer bone-bonding ability. To enhance the bonding strength of the coating layer, pretreatment with either O2 plasma or sandblasting was performed prior to sol-gel coating. Additionally, post-treatment with acid was carried out to confer apatite (calcium phosphate)-forming ability to the surface. Biomechanical and histological analyses performed using an in vivo rabbit tibia model showed that PEEK surfaces modified with sol-gel-derived TiO2 and acid post-treatment had better bone-bonding properties than uncoated PEEK surfaces. These modified surfaces also performed well in terms of their in vitro cell responses due to their modified surface chemistries and topographies. Although O2 plasma or sandblasting treatment were, for the most part, equivocal in terms of performance, we conclude that sol-gel-derived TiO2 coating followed by acid post-treatment significantly improves the bone bonding ability of PEEK surfaces, thus rendering them optimal for their use in surgical implants. The role of polyetheretherketone (PEEK) as an alternative biomaterial to conventional metallic implant materials has become increasingly important. However, its low bone bonding ability is yet to be resolved. This in vivo and in vitro investigation on the functionalization of PEEK surfaces highlights the utility of this material in clinical interventions that require implants, and may extend range of applications of PEEK. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Characteristics of nano Ti-doped SnO2 powders prepared by sol-gel method

International Nuclear Information System (INIS)

Liu, X.M.; Wu, S.L.; Chu, Paul K.; Zheng, J.; Li, S.L.

2006-01-01

Ti 4+ -doped SnO 2 nano-powders were prepared by the sol-gel process using tin tetrachloride and titanium tetrachloride as the starting materials. The crystallinity and purity of the powders were analyzed by X-ray diffraction (XRD) and the size and distribution of Ti 4+ -doped SnO 2 grains were studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that Ti 4+ has been successfully incorporated into the SnO 2 crystal lattice and the electrical conductivity of the doped materials improves significantly

Iron porphyrins doped sol-gel glasses: a chemometric study

Energy Technology Data Exchange (ETDEWEB)

Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R. [Soap Paulo Univ (USP), Sao Carlos (Brazil). Inst. de Fisica; Biazzotto, Juliana C.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ. (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Ciuffi, Katia J.; Mello, Cesar A.; Oliveira, Daniela C. de [Universidade de Franca , SP (Brazil)

2000-07-01

This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe (PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na){sub 4}Cl and Fe TCPP(Na){sub 4} Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established. The variables Solvent volume, fractional factorial design in two levels, 2{sup 5-1} type, generating 16 total experiments for each Fe P studied. (author)

Dielectric and piezoelectric properties of sol-gel derived Ca doped PbTiO3

International Nuclear Information System (INIS)

Chauhan, Arun Kumar Singh; Gupta, Vinay; Sreenivas, K.

2006-01-01

Synthesis of Ca doped PbTiO 3 powder by a chemically derived sol-gel process is described. Crystallization characteristics of different compositions Pb 1-x Ca x TiO 3 (PCT) with varying calcium (Ca) content in the range x = 0-0.45 has been investigated by DTA/TGA, X-ray diffraction and scanning electron microscopy. The crystallization temperature is found to decrease with increasing calcium content. X-ray diffraction reveals a tetragonal structure for PCT compositions with x ≤ 0.35, and a cubic structure for x = 0.45. Dielectric properties on sintered ceramics prepared with fine sol-gel derived powders have been measured. The dielectric constant is found to increase with increasing Ca content, and the dielectric loss decreases continuously. Sol-gel derived Pb 1-x Ca x TiO 3 ceramics with x = 0.45 after poling exhibit infinite electromechanical anisotropy (k t /k p ) with a high d 33 = 80 pC/N, ε' = 298 and low dielectric loss (tan δ = 0.0041)

The Effect of Cerium Ions on the Structure, Porosity and Electrochemical Properties of Si/Zr-Based Hybrid Sol-Gel Coatings Deposited on Aluminum

Directory of Open Access Journals (Sweden)

Peter Rodič

2018-04-01

Full Text Available This study was focused on the synthesis and characterization of Si/Zr-based hybrid sol-gel coatings with and without the addition of cerium(III ions. The coatings were deposited on aluminum aiming to act as an effective and ecologically harmless alternative to toxic chromate coatings. The chemical composition, structure, thermal properties and porosity of the non-doped and Ce-doped coatings containing various Zr contents were examined by Raman spectroscopy and photothermal beam deflection spectroscopy. The corrosion properties of the coated aluminum substrates were studied using AC and DC electrochemical methods in 0.1 M NaCl electrolyte solution. Barrier and protecting properties of the coatings were monitored upon long-term immersion in chloride solution using electrochemical impedance spectroscopy. The effect of cerium ions was two-fold: on the formation of a more condensed Si−O−Zr network structure and on the formation of Ce-based deposits, which diminish the rate of cathodic reaction at the coating/metal interface. These effects acted synergistically and resulted in the creation of the coatings with effective barrier and active corrosion protection.

Characteristics and optical properties of iron ion (Fe{sup 3+})-doped titanium oxide thin films prepared by a sol-gel spin coating

Energy Technology Data Exchange (ETDEWEB)

Wang, M.C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Lin, H.J. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China)], E-mail: hjlin@nuu.edu.tw; Yang, T.S. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China)

2009-04-03

Titanium dioxide (TiO{sub 2}) thin films doping of various iron ion (Fe{sup 3+}) concentrations have been prepared on a glass substrate by the sol-gel spin coating process. Characteristics and optical properties of TiO{sub 2} thin films doping of various Fe content were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-vis) and spectroscopic ellipsometry. The crystalline phase of TiO{sub 2} thin films comprised only the anatase TiO{sub 2}, but the crystallinity decreased when the Fe{sup 3+} content increased from 0 to 25.0 wt%. During the Fe{sup 3+} addition to 25.0 wt%, the phase of TiO{sub 2} thin film still maintained the amorphous state. The absorption edge of TiO{sub 2} thin films shifted towards longer wavelengths (i.e. red shifted) from 355 to 415 nm when the Fe{sup 3+}-doped concentration increased from 0 to 25.0 wt%. The values of the refractive index (n), and extinction coefficient (k), decreased with an increasing Fe{sup 3+} content. Moreover, the band-gap energy of TiO{sub 2} thin films also decreased from 3.29 to 2.83 eV with an increase in the Fe{sup 3+} content from 0 to 25.0 wt%.

Synthesis and nonlinear optical properties of zirconia-protected gold nanoparticles embedded in sol-gel derived silica glass

Science.gov (United States)

Le Rouge, A.; El Hamzaoui, H.; Capoen, B.; Bernard, R.; Cristini-Robbe, O.; Martinelli, G.; Cassagne, C.; Boudebs, G.; Bouazaoui, M.; Bigot, L.

2015-05-01

A new approach to dope a silica glass with gold nanoparticles (GNPs) is presented. It consisted in embedding zirconia-coated GNPs in a silica sol to form a doped silica gel. Then, the sol-doped nanoporous silica xerogel is densified leading to the formation of a glass monolith. The spectral position and shape of the surface plasmon resonance (SPR) reported around 520 nm remain compatible with small spherical GNPs in a silica matrix. The saturable absorption behavior of this gold/zirconia-doped silica glass has been evidenced by Z-scan technique. A second-order nonlinear absorption coefficient β of about -13.7 cm GW-1 has been obtained at a wavelength near the SPR of the GNPs.

Sol-gel bonding of silicon wafers

International Nuclear Information System (INIS)

Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

2005-01-01

Low temperature bonding of silicon wafers was achieved using sol-gel technology. The initial sol-gel chemistry of the coating solution was found to influence the mechanical properties of the resulting bonds. More precisely, the influence of parameters such as the alkoxide concentration, water-to-alkoxide molar ratio, pH, and solution aging on the final bond morphologies and interfacial fracture energy was studied. The thickness and density of the sol-gel coating were characterised using ellipsometry. The corresponding bonded specimens were investigated using attenuated total reflectance Fourier transformed infrared spectroscopy to monitor their chemical composition, infrared imaging to control bond integrity, and cross-sectional transmission electron microscopy to study their microstructure. Their interfacial fracture energy was measured using microindentation. An optimum water-to-alkoxide molar ratio of 10 and hydrolysis water at pH = 2 were found. Such conditions led to relatively dense films (> 90%), resulting in bonds with a fracture energy of 3.5 J/m 2 , significantly higher than those obtained using classical hydrophilic bonding (typically 1.5-2.5 J/m 2 ). Ageing of the coating solution was found to decrease the bond strength

Study of the Effect of Sol pH and Nanoclay Incorporation on the Corrosion Protection Performance of a Silane Sol-Gel Coating

Directory of Open Access Journals (Sweden)

Najmeh Asadi

2014-06-01

Full Text Available This work is aimed to evaluate the role of nanoclay in the protective performance of an eco-friendly silane sol-gel layer applied on mild steel substrate in 0.1M sodium chloride solution. At the first step, the effect of pH of the silane solution, consisting of a mixture of γ-glycidoxypropiltrimethoxysilane and methyltriethoxysilane and tetraethoxysilane, on the coating performance was evaluated through electrochemical noise measurements. The values of characteristic charge as a parameter extracted from shot noise theory revealed that the sol pH determining the rate of hydrolysis can play an important role in the corrosion protection behavior of silane coatings. Then, the influence of clay nanoparticles on the corrosion protective performance of the hybrid silane film was studied through taking advantage of electrochemical techniques, including electrochemical impedance spectroscopy and polarization curves, as well as surface analysis methods. The obtained electrochemical data including the values of charge transfer resistance, coating resistance, low frequency impedance and corrosion current density showed that the silane sol gel film in the presence of clay nanoparticles can present an improved corrosion protection. The behavior was connected to an enhancement in the coating barrier properties. Moreover, FESEM and water contact angle confirmed the higher reticulation in case of the coating incorporating nanoclay.

Sol-gel based oxidation catalyst and coating system using same

Science.gov (United States)

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

2010-01-01

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

Radiation hardening of sol gel-derived silica fiber preforms through fictive temperature reduction.

Science.gov (United States)

Hari Babu, B; Lancry, Matthieu; Ollier, Nadege; El Hamzaoui, Hicham; Bouazaoui, Mohamed; Poumellec, Bertrand

2016-09-20

The impact of fictive temperature (Tf) on the evolution of point defects and optical attenuation in non-doped and Er3+-doped sol-gel silica glasses was studied and compared to Suprasil F300 and Infrasil 301 glasses before and after γ-irradiation. To this aim, sol-gel optical fiber preforms have been fabricated by the densification of erbium salt-soaked nanoporous silica xerogels through the polymeric sol-gel technique. These γ-irradiated fiber preforms have been characterized by FTIR, UV-vis-NIR absorption spectroscopy, electron paramagnetic resonance, and photoluminescence measurements. We showed that a decrease in the glass fictive temperature leads to a decrease in the glass disorder and strained bonds. This mainly results in a lower defect generation rate and thus less radiation-induced attenuation in the UV-vis range. Furthermore, it was found that γ-radiation "hardness" is higher in Er3+-doped sol-gel silica compared to un-doped sol-gel silica and standard synthetic silica glasses. The present work demonstrates an effective strategy to improve the radiation resistance of optical fiber preforms and glasses through glass fictive temperature reduction.

Abstracts of International Conference on Sol-Gel Materials' 04

International Nuclear Information System (INIS)

2004-01-01

International Conference on Sol-Gel Materials '04 was an important forum for discussion on problems related to sol-gel processes applied for preparation materials with special physical properties and assignment. The application of sol-gel materials as phosphors, surface coatings, sensors, waveguides, medical implants, joints etc. has been presented. Preparation conditions, methods of physical characterization as well as optimal chemical composition of such materials have been also discussed in detail

Low temperature sol-gel process for optical coatings based on magnesium fluoride and titanium dioxide; Niedertemperatur Sol-Gel Verfahren fuer optische Schichtsysteme auf Basis von Magnesiumfluorid und Titandioxid

Energy Technology Data Exchange (ETDEWEB)

Krueger, Hannes

2009-09-24

This work deals with the development of a low temperature sol-gel spincoating process for thin films with thicknesses in the nanometer range based on metal oxides and metal fluorides. Optical films such as anti-reflective (AR) or high reflective coatings are of much interest and consist of alternating dielectric layers of low and high refractive index materials. Regarding the general procedure for the metal fluorides a novel nonaqueous sol-gel synthesis starting from metal alkoxides and alcohol-dissolved HF was used. The coatings were dried and calcined at 100 C. The morphology of these films was characterised with REM, TEM and AFM. EDX and XPS were used to identify the chemical composition and ellipsometry and UV-vis spectroscopy to determine the optical properties of the films. This new process allows the preparation of homogeneous magnesium fluoride and titanium dioxide layers with low roughness (R{sub a} {<=} 1,9 nm) on silicon and quartz substrates. The magnesium fluoride layers are partially amorphous or microcrystalline with crystallite sizes from 2 nm to 10 nm. The titanium dioxide layers are predominantly amorphous. The thicknesses of the magnesium fluoride and titanium dioxide single layers were adjustable between 25 nm and 500 nm depending on the number of coating steps and on the concentration of the used sols. The magnesium fluoride layers had a refractive index of n{sub 500} = 1,36 and the titanium dioxide layers a refraction index of n{sub 500} = 2,05. For the first time, an alternating metal fluoride and oxide multilayer system was produced with a low temperature sol-gel method (consisting of magnesium fluoride and titanium dioxide). Based on the determined optical constants of the magnesium fluoride and titanium dioxide single layers, AR and HR multilayer systems were calculated and fabricated. The transmission spectra of the designs and the corresponding multilayer were in good agreement. Similar results were obtained with the reflection spectra

Template-directed formation of functional complex metal-oxide nanostructures by combination of sol-gel processing and spin coating

International Nuclear Information System (INIS)

Choi, Y.C.; Kim, J.; Bu, S.D.

2006-01-01

We report the template-based formation of functional complex metal-oxide nanostructures by a combination of sol-gel processing and spin coating. This method employs the spin-coating of a sol-gel solution into an anodic aluminum oxide membrane (SSAM). Various metal-oxide nanowires and nanotubes with a high aspect-ratio were prepared. The aspect-ratios of the PbO 2 nanowires and Pb(Zr 0.52 Ti 0.48 )O 3 nanowires were about 300 and 400, respectively, and their diameters were about 50 nm. The fabricated PbTiO 3 nanotubes have a relatively constant wall thickness of about 20 nm with an outer diameter of about 60 nm. The deposition time for all of the fabricated metal-oxide nanowires and nanotubes is less than 120 s, which is far shorter than those required in both the sol-gel dipping and sol-gel electrophoretic methods. These results indicate that the SSAM method can be a versatile pathway to prepare functional complex metal-oxide nanowires and nanotubes with a high aspect-ratio. The possible formation process for the one-dimensional nanostructures by SSAM is discussed

Sol-gel synthesis of hydroxyapatite

International Nuclear Information System (INIS)

Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P.

2010-01-01

Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

Science.gov (United States)

Hayes, J D; Malik, A

2001-03-01

Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

Dielectric and piezoelectric properties of sol-gel derived Ca doped PbTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Arun Kumar Singh [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)]. E-mail: drvin_gupta@rediffmail.com; Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2006-06-15

Synthesis of Ca doped PbTiO{sub 3} powder by a chemically derived sol-gel process is described. Crystallization characteristics of different compositions Pb{sub 1-x}Ca {sub x}TiO{sub 3} (PCT) with varying calcium (Ca) content in the range x = 0-0.45 has been investigated by DTA/TGA, X-ray diffraction and scanning electron microscopy. The crystallization temperature is found to decrease with increasing calcium content. X-ray diffraction reveals a tetragonal structure for PCT compositions with x {<=} 0.35, and a cubic structure for x = 0.45. Dielectric properties on sintered ceramics prepared with fine sol-gel derived powders have been measured. The dielectric constant is found to increase with increasing Ca content, and the dielectric loss decreases continuously. Sol-gel derived Pb{sub 1-x}Ca {sub x}TiO{sub 3} ceramics with x = 0.45 after poling exhibit infinite electromechanical anisotropy (k {sub t}/k {sub p}) with a high d {sub 33} = 80 pC/N, {epsilon}' = 298 and low dielectric loss (tan {delta} = 0.0041)

Improvement of the titanium implant biological properties by coating with poly (ε-caprolactone)-based hybrid nanocomposites synthesized via sol-gel

Energy Technology Data Exchange (ETDEWEB)

Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 21, 81031 Aversa (Italy)

2016-05-18

When bioactive coatings are applied to medical implants by means of sol-gel dip coating technique, the biological proprieties of the implant surface can be modified to match the properties of the surrounding tissues. In this study organo-inorganic nanocomposites materials were synthesized via sol-gel. They consisted of an inorganic zirconium-based and silica-based matrix, in which a biodegradable polymer (the poly-ε-caprolactone, PCL) was incorporated in different weight percentages. The synthesized materials, in sol phase, were used to dip-coat a substrate of commercially pure titanium grade 4 (CP Ti gr. 4) in order to improve its biological properties. A microstructural analysis of the obtained films was carried out by scanning electron microscopy (SEM) and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR). Biological proprieties of the coated substrates were investigated by means of in vitro tests.

Highly sensitive and selective spectrofluorimetric determination of metoclopramide hydrochloride in pharmaceutical tablets and serum samples using Eu3+ ion doped in sol-gel matrix.

Science.gov (United States)

Attia, M S; Aboaly, M M

2010-06-30

A simple, sensitive and selective spectrofluorimetric method for the determination of Metoclopramide hydrochloride (MCP) is developed. The MCP can remarkably enhances the luminescence intensity of the Eu(3+) ion doped in sol-gel matrix at lambda(ex)=380 nm in DMSO at pH 8.7. The intensity of the emission band of Eu(3+) ion doped in sol-gel matrix increases due to energy transfer from MCP to Eu(3+) in the excited state. The enhancement of the emission band of Eu(3+) ion doped in sol-gel matrix at 617 nm was found to be directly proportional to the concentration of MCP with a dynamic range of 5 x 10(-9) - 1.0 x 10(-6) mol L(-1) and detection limit of 2.2 x10(-11) mol L(-1). Copyright 2010 Elsevier B.V. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-05-15

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

Preparation and studies of Eu3+ and Tb3+ co-doped Gd2O3 and Y2O3 sol-gel scintillating films

International Nuclear Information System (INIS)

Morales Ramirez, A. de J; Garcia Murillo, A.; Carrillo Romo, F. de J; Ramirez Salgado, J.; Le Luyer, C.; Chadeyron, G.; Boyer, D.; Moreno Palmerin, J.

2009-01-01

Eu 3+ (2.5 at.%) and Tb 3+ (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd 2 O 3 and Y 2 O 3 ) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 o C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm ± 0.2 (A = 0.0075 Tb 3+ ) and 24 nm ± 3.0 (B = 0.01 Tb 3+ ). After treatment at 700 o C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu 3+ - and Tb 3+ -doped Gd 2 O 3 and Y 2 O 3 powders showed that Tb 3+ contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb 3+ concentrations (down to 0.005 at.%) in both systems enhanced the light yield.

Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

Directory of Open Access Journals (Sweden)

I. Saurdi

2014-01-01

Full Text Available Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm, high average transmittance (96% in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtained for 2 at.% Sn-doped ZnO thin film. They were grown on sol-gel derived Sn-doped ZnO thin film, which acts as a seed layer, via sonicated sol-gel immersion method. The grown aligned ZnO nanorod arrays show high transmittance at visible region. The fabricated dye-sensitised solar cell based on the 2.0 at.% Sn-doped ZnO thin film with aligned ZnO nanorod arrays exhibits improved current density, open-circuit voltage, fill factor, and conversion efficiency compared with the undoped ZnO and 1 at.% Sn-doped ZnO thin films.

Generation of amorphous ceramic capacitor coatings on titanium using a continuous sol-gel process

International Nuclear Information System (INIS)

Dixon, B.G.; Walsh, M.A. III; Phillips, P.G.; Morris, R.S.

1995-01-01

Thin amorphous films of ceramic capacitor materials were successfully deposited using sol-gel chemistry onto titanium wire using a continuous, computer controlled process. By repeatedly depositing and calcining very thin layers of material, smooth and even coats can be produced. Surface analyses revealed the layered nature of these thin coats, as well as the amorphous nature of the ceramic. The electrical properties of the better coatings, all composed of niobium, bismuth, zinc oxides, were then evaluated. copyright 1995 Materials Research Society

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

Science.gov (United States)

Liu, D M; Troczynski, T; Tseng, W J

2001-07-01

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 of the solvents at 60 degrees C. X-ray diffraction showed that apatitic structure first appeared at a temperature as low as 350 degrees C. The crystal size and the HA content in both gels increase with increasing calcination temperature. The type of initial diluting media (i.e., water vs. anhydrous ethanol) did not affect the microstructural evolution and crystallinity of the resulting HA ceramic. The ethanol-based sol dip-coated onto a Ti substrate, followed by calcination at 450 degrees C, was found to be porous with pore size ranging from 0.3 to 1 microm. This morphology is beneficial to the circulation of physiological fluid when the coating is used for biomedical applications. The satisfactory adhesion between the coating and substrate suggests its suitability for load-bearing uses.

An investigation on linear optical properties of dilute Cr doped ZnO thin films synthesized via sol-gel process

International Nuclear Information System (INIS)

Kandjani, A. Esmaielzadeh; Tabriz, M. Farzalipour; Moradi, O. Mohammad; Mehr, H.R. Rezaeian; Kandjani, S. Ahmadi; Vaezi, M.R.

2011-01-01

Highlights: → In current work, ZnO:Cr thin films were synthesized via a simple sol-gel method. → By increasing in dopant concentration the average roughness of the film increases slightly while the thickness of these films remains constant. → By increase in dopant concentration band gap values of thin films show a decrease while the interior microstrain shows an increase based on increase in its Urbach energies. → By increase in annealing temperature band gap values and interior microstrains of thin films show a decrease. → By increase in number of applied dip coating, film thickness increase from 74 nm (after 1 procedure dip coating) to 147 nm (3 procedures dip coating), band gap values and interior microstrains of thin films show a decrease. - Abstract: Cr doped ZnO thin films were prepared via sol-gel method. The effects of dopant concentration (0%, 1.5% and 3%) annealing temperature and film thickness on UV-Vis spectra of prepared films were investigated. Also, the thickness and surface topology of thin films were investigated by thickness profile meter (DEKTAK) and Atomic Force Microscopy (AFM), respectively. In addition, the band gap and Urbach energy of prepared films were calculated completely for the samples. The results showed that by increasing the dopant concentrations, the microstrain of the prepared thin film structures also increases while the band-gap values decrease. Meanwhile, an increase in annealing temperature makes a decrease in band gap and microstrain of thin films. The increase in thickness resulted in red shift in band gap and reduction in interior microstrains.

Influences of the iron ion (Fe3+)-doping on structural and optical properties of nanocrystalline TiO2 thin films prepared by sol-gel spin coating

International Nuclear Information System (INIS)

Ben Naceur, J.; Mechiakh, R.; Bousbih, F.; Chtourou, R.

2011-01-01

Titanium dioxide (TiO 2 ) thin films doping of various iron ion (Fe 3+ ) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 deg. C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO 2 thin films comprised only the anatase TiO 2 , but the crystallinity decreased when the Fe 3+ content increased from 0% to 20%. During the Fe 3+ addition to 20%, the phase of TiO 2 thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (E g ) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe 3+ content.

Optical Constants of Crystallized TiO2 Coatings Prepared by Sol-Gel Process

Directory of Open Access Journals (Sweden)

Jun Shen

2013-07-01

Full Text Available Titanium oxide coatings have been deposited by the sol-gel dip-coating method. Crystallization of titanium oxide coatings was then achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studied by micro-Raman spectroscopy and atomic force microscopy, respectively. Characterization technique, based on least-square fitting to the measured reflectance and transmittance spectra, is used to determine the refractive indices of the crystallized TiO2 coatings. The stability of the synthesized sol was also investigated by dynamic light scattering particle size analyzer. The influence of the thermal annealing on the optical properties was then discussed. The increase in refractive index with high temperature thermal annealing process was observed, obtaining refractive index values from 1.98 to 2.57 at He-Ne laser wavelength of 633 nm. The Raman spectroscopy and atomic force microscopy studies indicate that the index variation is due to the changes in crystalline phase, density, and morphology during thermal annealing.

Tin dioxide sol-gel derived films doped with platinum and antimony deposited on porous silicon

NARCIS (Netherlands)

Savaniu, C.; Arnautu, A.; Cobianu, C.; Craciun, G.; Flueraru, C.; Zaharescu, M.; Parlog, C.; Paszti, F.; van den Berg, Albert

1999-01-01

SnO2 sol-gel derived thin films doped simultaneously with Pt and Sb are obtained and reported for the first time. The Sn sources were tin(IV) ethoxide or tin(II) ethylhexanoate, while hexachloroplatinic acid (H2PtCl6) and antimony chloride (SbCl3) were used as platinum and antimony sources,

Composite coating prepared by micro-arc oxidation followed by sol-gel process and in vitro degradation properties

International Nuclear Information System (INIS)

Zhang Yi; Bai Kuifeng; Fu Zhenya; Zhang Caili; Zhou Huan; Wang Liguo; Zhu Shijie; Guan Shaokang; Li Dongsheng; Hu Junhua

2012-01-01

A Mg phosphate coating was prepared on home-developed Mg-Zn-Ca alloy to improve its anticorrosion performance in simulated body fluid (SBF, Kokubo solution). The coating was prepared by micro-arc oxidation (MAO) method at the working voltage of 120-140 V. Evident improvement of anticorrosion was obtained even through the surface was porous. To further diminish the contact with SBF, a TiO 2 layer was coated on the porous MAO layer by sol-gel dip coating followed by an annealing treatment. The coatings were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The electrochemical performance of the MAO and TiO 2 /MAO coated alloys was evaluated by anodic polarization measurements. The pores on Mg phosphate layer provided accommodation sites for the subsequent TiO 2 sol-gel coating which sealed the pores and hence significantly enhanced the anticorrosion while single MAO coating only improve anticorrosion within a limited range. The present result indicates that fabrication of composite coatings is a significant strategy to improve the corrosion resistance of Mg-Zn-Ca alloy and other alloys, thus enhancing the potential of using Mg alloys as bio-implants.

Impact of Overlapping Fe/TiO2 Prepared by Sol-Gel and Dip-Coating Process on CO2 Reduction

Directory of Open Access Journals (Sweden)

Akira Nishimura

2016-01-01

Full Text Available Fe-doped TiO2 (Fe/TiO2 film photocatalyst was prepared by sol-gel and dip-coating process to extend its photoresponsivity to the visible spectrum. To promote the CO2 reduction performance with the photocatalyst, some types of base materials used for coating Fe/TiO2, which were netlike glass fiber and Cu disc, were investigated. The characterization of prepared Fe/TiO2 film coated on netlike glass fiber and Cu disc was analyzed by SEM and EPMA. In addition, the CO2 reduction performance of Fe/TiO2 film coated on netlike glass disc, Cu disc, and their overlap was tested under a Xe lamp with or without ultraviolet (UV light, respectively. The results show that the concentration of produced CO increases by Fe doping irrespective of base material used under the illumination condition with UV light as well as that without UV light. Since the electron transfer between two overlapped photocatalysts is promoted, the peak concentration of CO for the Fe/TiO2 double overlapping is approximately 1.5 times as large as the Fe/TiO2 single overlapping under the illumination condition with UV light, while the promotion ratio is approximately 1.1 times under that without UV light.

Infrared and Raman spectroscopic studies of tris-[3-(trimethoxysilyl)propyl] isocyanurate, its sol-gel process, and coating on aluminum and copper.

Science.gov (United States)

Li, Ying-Sing; Church, Jeffrey S; Woodhead, Andrea L; Vecchio, Nicolas E; Yang, Johnny

2014-11-11

Tris-[3-(trimethoxysilyl)propyl] isocyanurate (TTPI) has been used as a precursor to prepare a sol using ethanol as the solvent under acidic conditions. The sol-gel was applied for the surface treatment of aluminum and copper. Infrared and Raman spectra have been recorded for pure TTPI and the TTPI sol, xerogel and TTPI sol-gel coated metals. From the vibrational spectra, TTPI is likely to have the C1 point group. Vibrational assignments are suggested based on group frequencies, the expected reactions in the sol-gel process and the vibrational studies of some related molecules. From the experimental infrared spectra of xerogels annealed at different temperatures and from the thermal-gravimetric analysis, it is found that the TTPI xerogel decomposes at around 450°C with silica being the major decomposition product. A cyclic voltammetric study of the metal electrodes coated with different concentrations of TTPI ranging from 5% to 42% (v/v) has shown that the films with high concentrations of sol would provide better corrosion protection for aluminum and copper. Copyright © 2014 Elsevier B.V. All rights reserved.

Oxidative Treatment to Improve Coating and Electrochemical Stability of Carbon Fiber Paper with Niobium Doped Titanium Dioxide Sols for Potential Applications in Fuel Cells

International Nuclear Information System (INIS)

Alvar, Esmaeil Navaei; Zhou, Biao; Eichhorn, S. Holger

2014-01-01

Highlights: • Solution coating of metal oxide layer directly onto carbon paper. • Most uniform Metal oxide coating on functionalized carbon paper. • Highest electrochemical stability for metal oxide coated functionalized carbon paper. - Abstract: Regular hydrophobized carbon paper cannot be used for unitized regenerative fuel cell applications as it corrodes at high potentials on the oxygen electrode side. Reported here are the oxidative treatment and dip-coating of carbon paper (Spectracarb™ 2050A-0850) with Nb-doped TiO 2 sols (anatase phase) to increase the corrosion resistance of the carbon paper at the interface between catalyst layer and gas diffusion backing layer. Coating of carbon paper with Nb-doped TiO 2 sols generates a reasonably uniform layer of TiO 2 and covers the individual carbon fibers well only if the carbon paper is oxidatively functionalized prior to coating. This can be reasoned with a better wetting of the functionalized carbon paper by the sol-gel and the formation of covalent bonds between Ti and the large number of functional groups on the surface of oxidized carbon paper, which is in good agreement with previous observation for carbon nanotubes. The resistance towards oxidation of coated and uncoated samples of untreated and functionalized carbon paper was probed by cyclic voltammetry in 0.5 M aqueous H 2 SO 4 at 1.2 V versus Ag/AgCl for up to 72 hours to mimic the conditions in a unitized regenerative fuel cell. Among these four cases studied here, functionalized carbon paper coated with a layer of Nb-doped TiO 2 shows the highest stability towards electrochemical oxidation while uncoated functionalized carbon paper is the least stable due to the large number of available oxidation sites. These results clearly demonstrate that a coating of carbon fibers with TiO 2 generates a lasting protection against oxidation under conditions encountered at the oxygen electrode side of unitized regenerative fuel cells

Vanadium dioxide formed by the sol-gel process

International Nuclear Information System (INIS)

Potember, R.S.; Speck, K.R.; Hu, H.S.

1990-01-01

This patent describes a process for the deposition of a crystalline vanadium dioxide thin film. It comprises: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film

Anion embedded sol-gel films on Al for corrosion protection

International Nuclear Information System (INIS)

Sheffer, Mari; Groysman, Alec; Starosvetsky, David; Savchenko, Natali; Mandler, Daniel

2004-01-01

We report here on the successful incorporation of organic anions into a sol-gel film on Al as a means of enhancing the protection against corrosion. Following our previous study where we showed that hydrophobic sol-gel films provided pronounced corrosion inhibition, we studied the corrosion inhibition that phenylphosphonic acid (PPA) has when embedded inside a thin sol-gel coating on Al. The anion of this organic anion tends to stay inside a phenyltrimethoxysilane (PTMOS) based sol-gel film due to π-interactions. Our findings, which are derived primarily from potentiodynamic polarization measurements, electrochemical noise, scanning electron microscopy measurements and Auger electron spectroscopy (AES), clearly show that the organic phosphonate adds to the protection efficiency of the sol-gel film

Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

Energy Technology Data Exchange (ETDEWEB)

Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Makassar 90245 (Indonesia); Sugianto,; Maddu, A. [Department of Physics, Faculty of Mathematics and Natural Sciences, Bogor Institute of Culture, IPB Bogor (Indonesia)

2014-09-25

Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.

Sol-gel materials for optofluidics - process and applications

DEFF Research Database (Denmark)

Mikkelsen, Morten Bo Lindholm

2011-01-01

This Ph.D. thesis is concerned with the use of sol-gel materials in optofluidic applications and the physics of DNA molecules in nanoconfinement. The bottom-up formation of solid material, which is provided by the sol-gel process, enables control of the chemical composition and porosity...... of the material. At early stages of gelation, thin gel coatings can be structured by nanoimprint lithography, and purely inorganic silica materials can be obtained by subsequent thermal annealing. The sol-gel process thus constitutes a unique method for nanofabrication of silica materials of special properties....... In this work, sol-gel silica is introduced as a new material class for the fabrication of lab-on-a-chip devices for DNA analysis. An imprint process with a rigid, non-permeable stamp was developed, which enabled fabrication of micro- and nanofluidic silica channels in a single process step without use of any...

Co-doping effect of CaS and Nd2S3 nanocrystallites on luminescence properties of sol-gel SiO2 xerogel

International Nuclear Information System (INIS)

Yang, P.; Lue, M.K.; Song, C.F.; Xu, D.; Yuan, D.L.; Gu, F.

2005-01-01

The synthesis and photoluminescence characteristics of a porous phosphor silica xerogel containing CaS and Nd 2 S 3 nanoparticles entrapped in a sol-gel silica network are discussed. X-ray diffraction (XRD), transmission electron micrograph (TEM), UV-Vis absorption spectroscopy and photoluminescence spectroscopy have been performed. The observed luminescence is assigned to CaS and Nd 2 S 3 nanoparticles embedded in the sol-gel silica xerogel. Transmission electron micrographs of doped samples revealed the presence of CaS and Nd 2 S 3 nanoparticles with average diameters of 10-20 nm. Two emission bands have been observed from co-doped sample

Monolayer nanoparticle-covered liquid marbles derived from a sol-gel coating

Science.gov (United States)

Li, Xiaoguang; Wang, Yiqi; Huang, Junchao; Yang, Yao; Wang, Renxian; Geng, Xingguo; Zang, Duyang

2017-12-01

A sol-gel coating consisting of hydrophobic SiO2 nanoparticles (NPs) was used to produce monolayer NP-covered (mNPc) liquid marbles. The simplest approach was rolling a droplet on this coating, and an identifiable signet allowed determination of the coverage ratio of the resulting liquid marble. Alternatively, the particles were squeezed onto a droplet surface with two such coatings, generating surface buckling from interfacial NP jamming, and then a liquid marble was produced via a jamming-relief process in which water was added into the buckled droplet. This process revealed an ˜7% reduction in particle distance after interfacial jamming. The mNPc liquid marbles obtained by the two methods were transparent with smooth profiles, as naked droplets, and could be advantageously used in fundamental and applied researches for their unique functions.

Architectural optimization of an epoxy-based hybrid sol-gel coating for the corrosion protection of a cast Elektron21 magnesium alloy

Science.gov (United States)

Murillo-Gutiérrez, N. V.; Ansart, F.; Bonino, J.-P.; Kunst, S. R.; Malfatti, C. F.

2014-08-01

An epoxy-based hybrid sol-gel coating was prepared in various architectural configurations has been studied for the corrosion protection of a cast Elektron21 magnesium alloy. The creation of a single layer of this coating presents defects consisting of macro-pores and protuberances, which opens access for corrosive species to reach the metallic substrate. These defects are suspected to result from the high reactivity of the substrate, as well as to the irregular topography of the substrate disrupted by the microstructure of the own magnesium alloy. Hence, a sol-gel coating in bilayer architecture is proposed, where the first layer would “inert” the surface of the magnesium substrate, and the second layer would cover the defects of the first layer and also thickening the coating. The morphological characteristics of the sol-gel coatings were analyzed by scanning electron microscopy (SEM), and their corrosion behavior was evaluated by OCP (open circuit potential) monitoring and electrochemical impedance spectroscopy (EIS) in chloride media. It is shown that both the architectural arrangement and the individual thickness of the first and second layers have an important influence on the anticorrosion performances of the protective system, just as much as its global thickness.

Effect of Sn doping on structural, mechanical, optical and electrical properties of ZnO nanoarrays prepared by sol-gel and hydrothermal process

Science.gov (United States)

Agarwal, Manish Baboo; Sharma, Akash; Malaidurai, M.; Thangavel, R.

2018-05-01

Undoped and Sn doped Zinc oxide nanorods were prepared by two step process: initially growth of seed layers by sol-gel spin coating technique and then zinc oxide nanorods by hydrothermal process using the precursors zinc nitrate hexahydrate, hexamine and tin chloride. The effects on the electrical, optical, mechanical and structural properties for various Sn concentrations were studied. The crystalline phase determination from X-ray diffraction (XRD) confirms that Sn doped ZnO nanorods have hexagonal wurtzite structure. The variations of stress and strain with different doping concentration of Sn in ZnO nanorods were studied. The doping effect on electrical properties and optical bandgap is estimated by current voltage characteristics and absorbance spectra respectively. The surface morphology was studied with field emission scanning electron microscope (FESEM), which shows that the formation of hexagonal nanorods arrays with increasing Sn concentration. The calculated value of Young's modulus of elasticity (Y) for all the samples remains same. These results can be used in optoelectronic devices.

New Functionalized Sol-Gel Hybrid Sorbent Coating for Stir Bar Sorptive Extraction of Selected Non-Steroidal Anti Inflammatory Drugs in Human Urine Samples

International Nuclear Information System (INIS)

Mashkurah Abd Rahim; Wan Aini Wan Ibrahim; Zainab Ramli; Mohd Marsin Sanagi

2015-01-01

A new sol-gel hybrid material, methyltrimethoxysilane-cyanopropyltriethoxysilane (MTMOS-CNPrTEOS) was successfully synthesized and used as a coating material in stir bar sorptive extraction (SBSE) of selected non-steroidal anti-inflammatory drugs (NSAIDs) in urine samples. The MTMOS-CNPrTEOS hybrid was synthesized by hydrolysis and condensation of MTMOS and CNPrTEOS in the presence of trifluoroacetic acid as catalyst via sol-gel method. Several factors influencing the synthesized sol-gel hybrid MTMOS-CNPrTEOS process such as mole ratio of MTMOS-CNPrTEOS, NaOH concentrations as etching solution, etching time, coating time and water content were investigated and optimized in this study. The optimum synthesis conditions obtained were 1:1 mol ratio of MTMOS-CNPrTEOS, 1 M NaOH as etching solution, 60 min etching time, 2 h coating time and 6 mmol water. The sol-gel hybrid MTMOS-CNPrTEOS synthesized under the optimum conditions was used to determine selected NSAIDs in human urine samples using normal stacking mode capillary electrophoresis with ultraviolet detection. MTMOS-CNPrTEOS SBSE method demonstrated good linearity (60 to 20,000 μg L -1 ) with excellent coefficient of determination (r 2 > 0.9990). The sol-gel hybrid MTMOS-CNPrTEOS SBSE method showed low limit of detection (35 - 41 μg L -1 ) with good precision (RSD < 6 %, n = 3) and excellent extraction recoveries (83.5 - 98.9 %) for the selected NSAIDs. The sol-gel hybrid MTMOS-CNPrTEOS SBSE method demonstrated good potential as an alternative sorbent in SBSE method for NSAIDs. (author)

Influence of precursor ratios on the properties of cotton coated with a sol-gel flame retardant

CSIR Research Space (South Africa)

Chapple, Stephen A

2006-11-01

Full Text Available Cotton has many desirable properties, but is flammable. The flame retardant treatment of cotton is an important textile process. To study the effect of a sol-gel phosphate-based flame-retardant coating on fabric properties (flammability, stiffness...

Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

International Nuclear Information System (INIS)

Tabassum, Samia; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2016-01-01

Highlights: • Al-doped ZnO thin film was deposited by sol-gel method in different annealing temperature and duration. • We examined the environmental stability in ambient and damp heat condition. • We investigated chemical state of thin film. • Better stability was observed in the film annealed at high temperature (600 °C) along with longer duration (120 min). • An ultrathin aluminum oxide layer formation was predicted by XPS measurement which protects further oxidation and improves stability. - Abstract: Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.

Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Tabassum, Samia, E-mail: shawon14@gmail.com; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2016-07-30

Highlights: • Al-doped ZnO thin film was deposited by sol-gel method in different annealing temperature and duration. • We examined the environmental stability in ambient and damp heat condition. • We investigated chemical state of thin film. • Better stability was observed in the film annealed at high temperature (600 °C) along with longer duration (120 min). • An ultrathin aluminum oxide layer formation was predicted by XPS measurement which protects further oxidation and improves stability. - Abstract: Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.

Influence of Ce{sup 3+} doping on molecular organization of Si-based organic/inorganic sol-gel layers for corrosion protection

Energy Technology Data Exchange (ETDEWEB)

Fedel, Michele, E-mail: michele.fedel@unitn.it [Department of Industrial Engineering, University of Trento, via Sommarive 9, Povo (Italy); Callone, Emanuela [Department of Industrial Engineering, University of Trento, via Sommarive 9, Povo (Italy); “K. Müller” Magnetic Resonance Lab, University of Trento, via Sommarive 9, Povo (Italy); Fabbian, Matias; Deflorian, Flavio [Department of Industrial Engineering, University of Trento, via Sommarive 9, Povo (Italy); Dirè, Sandra [Department of Industrial Engineering, University of Trento, via Sommarive 9, Povo (Italy); “K. Müller” Magnetic Resonance Lab, University of Trento, via Sommarive 9, Povo (Italy)

2017-08-31

Highlights: • Ce{sup 3+} ions promote a decrease of the degree of condensation of the silsesquioxane network. • Ce{sup 3+} ions affect ladder and cages like structures formation in the silsesquioxane network. • Ce{sup 3+} ions do not significantly affect the barrier properties of the coatings. • [Ce{sup 3+}] ≈ 5·10{sup −4} M provides the sol-gel film with an effective passivating potential. - Abstract: In this work, organosilane-derived sol-gel films containing different amounts of cerium ions applied on AA 1050 were investigated. The sol-gel coatings were prepared from 3-glycidoxypropyltrimethoxysilane (GPTMS) and methyltriethoxysilane (MTES) mixtures with the addition of cerium nitrate in order to achieve different concentrations of Ce ions (from 10{sup −5} M to 10{sup −2} M). The effect of the cerium load on the structure of the cured sol-gel films was investigated by means of solid state NMR and FT-IR spectroscopy. The corrosion protection properties of the different sol-gel layers were investigated mainly by means potentiodynamic curves and electrochemical impedance spectroscopy (EIS). FT-IR and solid state NMR suggested a significant influence of the Ce cations on the network structure: not only the degree of condensation decreases with Ce addition but also the structural modification of the silsesquioxane network is observed with preferential formation of ladder-like species for low Ce{sup 3+} content and cages predominance for Ce/Si molar ratio greater than 0.039, i.e. [Ce{sup 3+}] = 1·10{sup −4} M. Electrochemical tests revealed that the effect of Ce ions on the structure of the coatings does not lead to remarkable changes in the barrier properties. Moreover, it was found that the Ce ions seems to be present in the cured films and are able to migrate towards the metal/coating interface thus providing a stabilization of the metal interface.

Evaluation of sol-gel coatings modified with Al2O3 nanoparticles for the protection of AA 2024 aluminum alloy

International Nuclear Information System (INIS)

Vargas, E; Pineda, F; Sancy, M; Paez, M.A

2008-01-01

AA 2024 aluminum alloys have broad applications in the aeronautics industry, since they have an excellent mechanical resistance: weight ratio. The increased mechanical resistance of aluminum is achieved by alloying copper with other metals, as well as by submitting the material to thermal treatments. However, its heterogeneous composition and metallurgical history fosters the generation of galvanic piles that cause localized pitting and intergranular corrosion on the metallic surface in aggressive environments. Given the catastrophic corrosion of aluminum alloys used in aeronautics, the traditional methods of protection include multi-stage processes that involve anodizing, the incorporation of additives in case of water permeability and painting of the metallic piece. This is an efficient process in terms of protection but highly toxic and contaminating due to the handling of elevated concentrations of Cr 6+ . Among alternative methodologies the most outstanding are protective coatings obtained with the sol-gel technique. This type of coating, however, has drawbacks, mostly associated with its low adherence and limited mechanical properties. Considering the above, this work studied the effect of adding AI 2 0 3 to zirconium polymeric matrices, for their application as anticorrosive coatings in the protection of AA 2024 surfaces. The evaluation of the doped coatings with nanoparticles compared to those without doping was carried out using potentiodynamic polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The results show that the zirconium coatings doped with a low concentration of nanoparticulated additive and submitted to a consolidation treatment at reduced pressure display a significant drop in the population of fractures, responding directly to an increase in their corrosion protection

Influence of crosslinker structure on performance of functionalised organic-inorganic hybrid sol-gel coating

Science.gov (United States)

Vasiljević, J.; Zorko, M.; Štular, D.; Tomšič, B.; Jerman, I.; Orel, B.; Medved, J.; Simončič, B.

2017-10-01

This research aimed to investigate the influence of the co-condensation of the three different organofunctional trialkoxysilane precursors with two different crosslinkers, i.e. tetraethoxysilane or organocyclotetrasiloxane on the performance and the washing fastness of this multicomponent multifunctional sol-gel coating on cellulose fibres. To this aim, a three-component equimolar sol mixture (MC), which included 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF), 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQ) and P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) in combination with two different concentrations of TEOS (T and 3T) or organocyclotetrasiloxane 2,4,6,8-tetrakis(2-(diethoxy(methyl)silyl)ethyl)-2,4,6,8-tetramethyl-cyclotetrasiloxane (T4) as crosslinkers, was applied to the cotton fibres by a pad-dry-cure process. The functional properties of the coated samples before and after repeated washing were investigated by the water θ (W) and n-hexadecane θ (C16) static contact angle as well as water sliding (roll-off) (α) angle measurements. The inclusion of both TEOS and T4 into the MC sol increased the hydrophobic affect and simultaneously decreased the oleophobic effect of the MC coating. These phenomena were more pronounced for higher concentration of TEOS and T4 crosslinker. The inclusion of T4 into the MC sol improved the coating washing fastness to a significantly higher extent than the inclusion of TEOS, with respect to the applied concentrations.

Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

OpenAIRE

Sridevi , D.V ,; Ramesh , V; Sakthivel , T; Geetha , K ,; Ratchagar , V ,; Jagannathan , K ,; Rajarajan , K ,; Ramachadran , K ,

2017-01-01

International audience; A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP) and 2–propanol as a common starting material and the obtained products were calcined at 450˚C450˚450˚C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functi...

Sol-Gel-Derived Hydroxyapatite-Carbon Nanotube/Titania Coatings on Titanium Substrates

Directory of Open Access Journals (Sweden)

Chuantong Liu

2012-04-01

Full Text Available In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO₂ double layer coatings were successfully developed on titanium (Ti substrates intended for biomedical applications. A TiO₂ coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO₂ coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO₂ double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO₂ coatings on Ti substrates might be a promising material for bone replacement.

Synthesis of hybrid sol-gel coatings for corrosion protection of we54-ae magnesium alloy

International Nuclear Information System (INIS)

Hernández-Barrios, C A; Peña, D Y; Coy, A E; Duarte, N Z; Hernández, L M; Viejo, F

2013-01-01

The present work shows some preliminary results related to the synthesis, characterization and corrosion evaluation of different hybrid sol-gel coatings applied on the WE54-AE magnesium alloy attending to the two experimental variables, i.e. the precursors ratio and the aging time, which may affect the quality and the electrochemical properties of the coatings resultant. The experimental results confirmed that, under some specific experimental conditions, it was possible to obtain homogeneous and uniform, porous coatings with good corrosion resistance that also permit to accommodate corrosion inhibitors

Sol-gel process for preparation of YBa2Cu4O8 from acidic acetates/ammonia/ascorbic acid systems

International Nuclear Information System (INIS)

Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.

1997-01-01

YBa 2 Cu 4 O x sols were prepared by addition of ammonia to acidic acetate solutions of Y 3+ , Ba 2+ , and Cu 2+ . Ascorbic acid was added to part of the sol. The resultant sols were gelled to a shard or a coating by evaporation at 60 C. Addition of ethanol to the sols facilitated formation of gel coatings, fabricated by a dipping technique, on Ag or glass or substrates. At 100 C, gels formed in the presence of ascorbic acid were perfectly amorphous, in contrast to crystalline acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings

Mechanical properties of chemically bonded sand core materials dipped in sol-gel coating impregnated with filter

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Tiedje, Niels Skat

2012-01-01

A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force-...... of the chemically bonded sand core materials, a combination of flexural and compression tests is suggested for improving the casting quality. © 2012 W. S. Maney & Son Ltd.......A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force...... the strengths were increased under compression. The mode of fracture of the chemically bonded sand core materials was observed to be intergranular through the binder. The stiffness of the chemically bonded sand core materials was determined. For better understanding of the mechanical properties...

Morphology of one-time coated palladium-alumina composite membrane prepared by sol-gel process and electroless plating technique

Science.gov (United States)

Sari, R.; Dewi, R.; Pardi; Hakim, L.; Diana, S.

2018-03-01

Palladium coated porous alumina ceramic membrane tube was obtained using a combination of sol-gel process and electroless plating technique. The thickness, structure and composition of palladium-alumina composite membrane were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and atomic force microscopy (AFM). Palladium particle size was 6.18 to 7.64 nm. Palladium membrane with thickness of approximately 301.5 to 815.1 nm was formed at the outer surface of the alumina layer. EDX data confirmed the formation of palladium-alumina membrane containing 45% of palladium. From this research it shows the combination of sol-gel process and electroless plating technique with one-time coating can produce a homogeneous and smoother palladium nano layer film on alumina substrate.

The adhesion strength and residual stress of colloidal-sol gel derived β-Tricalcium-Phosphate/Fluoridated-Hydroxyapatite biphasic coatings

International Nuclear Information System (INIS)

Cheng Kui; Zhang, Sam; Weng Wenjian; Khor, Khiam Aik; Miao Shundong; Wang Yongsheng

2008-01-01

β-tricalcium phosphate (β-TCP) powders are embedded in a fluoridated hydroxyapatite (FHA) matrix to form β-TCP-FHA composites via colloidal-sol gel method. This composite layer is deposited on top of a FHA layer to form a β-TCP-FHA/FHA biphasic coating. The effect of the nanosized powder on the residual stress is characterized through the X-ray diffraction peak shift. The powder incorporation increases the residual stress, while a large amount of β-TCP (Ca powder /Ca sol ratio is higher than 1/2) results in less gel shrinkage that partially compensates the mismatch of thermal expansion coefficient and thus the residual stress. Despite the elevated residual stress as more powders are embedded, the coating adhesion strength remains virtually constant: around 430 mN-500 mN in scanning scratch test

Sol-gel optical thin films for an advanced megajoule-class Nd:glass laser ICF-driver

International Nuclear Information System (INIS)

Floch, H.G.; Belleville, P.F.; Pegon, P.M.; Dijonneau, C.S.; Guerain, J.

1995-01-01

It is well established by manufacturers and users that optical coatings are generally prepared by the well known Physical Vapor Deposition (PVD) technology. In the authors' opinion sol-gel technology is an effective and competitive alternative. The aim of this paper is to emphasize on the sol-gel thin film work carried out at Centre d'Etudes de Limeil-Valenton (CEL-V) and concerning the technology for high power lasers. The authors will briefly discuss the chemistry of the sol-gel process, the production of optical coatings and the related deposition techniques. Finally, the paper describes the preparation and performance of sol-gel optical coatings they have developed to fulfill the requirements of a future 2 MJ/500 TW (351 nm) pulsed Nd:glass laser so-called LMJ (Laser MegaJoules). This powerful laser is to be used for their national Inertial Confinement Fusion (ICF) program, to demonstrate at the laboratory scale, ignition of deuterium-tritium fusion fuel. Moreover, the aim of this article is, hopefully, to provide a convincing argument that coatings and particularly optical coatings, are some of the useful products available from sol-gel technology, and that exciting developments in other areas are almost certain to emerge within the coming decade

Sol-gel-processed yttrium-doped NiO as hole transport layer in inverted perovskite solar cells for enhanced performance

Science.gov (United States)

Hu, Zijun; Chen, Da; Yang, Pan; Yang, Lijun; Qin, Laishun; Huang, Yuexiang; Zhao, Xiaochong

2018-05-01

In this work, high-performance inverted planar perovskite solar cells (PSCs) using sol-gel processed Y-doped NiO thin films as hole transport layer (HTL) were demonstrated. Y-doped NiO thin films containing different Y doping concentrations were successfully prepared through a simple sol-gel process. The Y doping could significantly improve the electrical conductivity of NiO thin film, and the photovoltaic performance of Y-doped NiO HTL-based PSC devices outperformed that of the pristine NiO HTL-based device. Notably, the PSC using a 5%Y-NiO HTL exhibited the champion performance with an open-circuit voltage (Voc) of 1.00 V, a short circuit current density (Jsc) of 23.82 mA cm-2, a fill factor (FF) of 68% and a power conversion efficiency (PCE) of 16.31%, resulting in a 27.62% enhancement in PCE in comparison with the NiO device. The enhanced performance of the Y-doped NiO device could be attributed to the improved hole mobility, the high quality compact active layer morphology, the more efficient charge extraction from perovskite absorber as well as the lower recombination probability of charge carriers. Thus, this work provides a simple and effective approach to improve the electrical conductivity of p-type NiO thin films for use as a promising HTL in high performance PSCs.

Characterization of ceramic sol-gel coatings as an alternative chemical conversion treatment on commercial carbon steel

International Nuclear Information System (INIS)

Dominguez-Crespo, M.A.; Garcia-Murillo, A.; Torres-Huerta, A.M.; Carrillo-Romo, F.J.; Onofre-Bustamante, E.; Yanez-Zamora, C.

2009-01-01

Sol-gel yttria-stabilized zirconia (YSZ) thin films were prepared on commercial carbon steel sheets by dip-coating technique followed by a low temperature heat treatment (473, 573, and 673 K for 1 h) in order to improve both corrosion properties and adhesion. For comparison, zirconia (ZrO 2 ) coatings have been also analyzed. Electrochemical techniques, Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the anticorrosion behavior of the coatings in a 3.5 wt% NaCl solution. The adhesion with a polyester organic coating was evaluated by the pull-off technique. The typical thickness of the deposited layers ranged from 1 to 1.3 μm depending on process parameters. The obtained results indicated that sol-gel ZrO 2 and YSZ coatings without an organic coating can act as protective barriers against wet corrosion during the first hours, but they fail when the time exposure is longer than 1 day. However, when synthesized films were used as a pre-treatment and an organic coating was added (top-coated), the anticorrosive and adhesion properties were strongly affected by the temperature of the treatment, and an increase in both properties was observed at higher temperatures. The structural and morphological characteristics of the coating provide an explanation of the role of each film in the electrochemical behavior in this aggressive medium. Comparing both systems, YSZ displayed greater protective and adhesion values than exhibited for ZrO 2 which can be correlated with the stabilization of the cubic phase

On the healing mechanism of sol-gel derived hybrid materials containing dynamic di-sulfide bonds

NARCIS (Netherlands)

AbdolahZadeh, M.; Esteves, A.C.C.; Van der Zwaag, S.; Garcia Espallargas, S.J.

2013-01-01

Sol-gel technology is increasingly being used in coatings for corrosion protection and adhesion improvement. So far, the self-healing concept in sol-gel coatings has only been approached from extrinsic healing perspective (i.e. use of nano and micro carriers of corrosion inhibitors) [1]. Despite the

Mesoscopic objects, porous layers and nanocomposites-Possibilities of sol-gel chemistry

International Nuclear Information System (INIS)

Piwonski, Ireneusz

2009-01-01

The goal of this study was to prepare mesoscopic objects, thin porous films and nanocomposite coatings with the use of sol-gel technique. Silica nanotubes, titania nanoparticles, porous titania and zirconia coatings as well as titania nanocomposites were successfully synthesized by changing the type of sol-gel precursor, sol composition and applying dip-coating deposition procedure in order to obtain thin films or coatings. All materials were visualized and characterized by the Atomic Force Microcscopy (AFM) technique. Moreover, characterization of titania nanocomposites was extended to the tribological tests performed by means of microtribometer operating in normal loads range of 30-100 mN. The AFM analysis of mesoscopic objects and nanoparticles showed that the diameter of synthesized silica nanotubes was 60-70 nm and the size of titania nanoparticles was 43 nm. In case of porous layers the pore size in titania and zirconia coatings oscillated between 100 and 240 nm, however their shape and distribution were irregular. Microtribological studies of nanocomposites revealed the moderate decrease of the coefficient of friction for samples containing 5, 15 and 5 wt.% of zirconia nanoparticles in titania coatings annealed at 100, 500 and 1000 deg. C respectively. An enhancement of antiwear properties was already observed for 1 wt.% of nanophase content, except the sample annealed at 500 deg. C. It was also found that the annealing at high temperatures is a primary factor which affects the reduction of friction and wear of titania coatings while the presence of nanoparticles has secondary effect. Investigations in this study carried out with the use of the AFM technique highlighted the potential and flexibility of sol-gel approach in designing of various types of advanced materials in a form of mesoscopic objects, porous coatings and composite layers. Results collected in this study clearly demonstrated that sol-gel technique can be applied effectively in preparation of

Metal-silica sol-gel materials

Science.gov (United States)

Stiegman, Albert E. (Inventor)

2002-01-01

The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

Thoria sol-gel processes

International Nuclear Information System (INIS)

Matthews, R.B.

1978-10-01

Alternate fuel fabrication techniques are being developed at WNRE as part of the thorium fuel cycle program. The sol-gel techniques are attractive and this report assembles and summarizes information relating to thoria sol-gel fuels. Some background information on the behaviour and advantages of sol-gel fuel forms is presented, followed by a review of relevant colloid chemistry and an explanation of the fundamental steps of sol-gel processes. Finally, several variants to the basic process are reviewed and evaluated. (author)

Deposition of tin oxide doped with fluorine produced by sol-gel method and deposited by spray-pyrolysis

International Nuclear Information System (INIS)

Maia, Paulo Herbert Franca; Lima, Francisco Marcone; Sena, Aline Cosmo de; Silva, Alvaro Neuton; Almeida, Ana Fabiola Leite de; Freire, Francisco Nivaldo Aguiar

2014-01-01

Solar energy is one of the most important sources of renewable energy today, but its production is based on silicon cells, expensive and difficult to produce, so the research seek new materials to replace them. This work aims to deposit tin oxide doped with fluorine on the glass substrate using the sol-gel method to provide a working solution and spray pyrolysis technique to perform the deposition. F-SnO2 (FTO) were synthesized by sol-gel method, employing NH_4F and SnCl_2 precursor in an ethanol solution. Before the formation of the gel phase, the entire solution was sprayed, with the aid of a pistol aerographic substrate under heated at 600 °C divided by 50 applications and cooled in the furnace. The substrates had resistances between 10 and 30 S.cm. The energy dispersive x-ray (EDS) revealed the presence of fluorine in the SnO_2 network. (author)

Recubrimientos de hidroxiapatita preparados mediante un proceso sol-gel

Directory of Open Access Journals (Sweden)

Peón, E.

2005-12-01

Full Text Available Hydroxyapatite coatings (HAp have been obtained starting from precursors of sol-gel type. The coatings previously oxidized were deposited on metal surfaces of a based on iron alloy so-called MA956. The alloys were at high temperatures, in order to improve the adhesion with the hydroxyapatite coatings. The sol-gel coating was obtained applying an aqueous route, using triethyl phosphite and aqueous calcium nitrate, as precursors of phosphorous and calcium, respectively. Different sintering thermal treatments were applied on the resulting gels in order to obtain a homogeneous, adherent and crystalline hydroxyapatite coating. The characterization techniques used for this study were optical microscopy, SEM/EDX, XDR and FTIR. Moreover, the adhesion between the hydroxylapatite coating and the substrate was assessed according to the ASTM D 3359-02 standard test method. The results of this study showed that the best thermal treatment is obtained for a sintering temperature of 550 °C during a time of 72 h.

Se han preparado nuevos recubrimientos de hidroxiapatita (HAp obtenidos a partir de precursores de tipo sol-gel, depositados sobre sustratos metálicos de una aleación de base hierro denominada MA956, previamente oxidados a elevadas temperaturas, para mejorar la adherencia con los recubrimientos de hidroxiapatita. El recubrimiento sol-gel se obtuvo aplicando una ruta acuosa, utilizando como precursores del fósforo y del calcio trietilfosfito y nitrato cálcico tetrahidratado, respectivamente. Sobre los geles resultantes se aplicaron distintos tratamientos térmicos de sinterización, hasta la obtención de recubrimientos de hidroxiapatita homogéneos, adherentes y cristalinos. Las técnicas de caracterización utilizadas para realizar este estudio han sido microscopía óptica, MBE/EDX, DRX y FTIR. Así mismo, se ha determinado la adherencia entre el substrato y el recubrimiento de hidroxiapatita según la norma ASTM D 3359-02. Los resultados

Recobrimento da liga Ti-6Al-4V com hidroxiapatita pelo método sol-gel e sua aplicação a hastes femorais não-cimentadas Coating of Ti-6Al-4V alloy with hydroxyapatite by using sol-gel method and its application to non-cemented femoral stem

Directory of Open Access Journals (Sweden)

E. P. Avés

2008-12-01

Full Text Available O recobrimento de ligas metálicas com cerâmicas bioativas visa acelerar a formação óssea ao redor do implante, contribuindo para a sua estabilização. Neste trabalho estudou-se a fase cerâmica de hidroxiapatita depositada pelo processo sol-gel em chapas da liga metálica Ti-6Al-4V. A camada de recobrimento foi caracterizada por microscopia eletrônica de varredura, por difração de raios X e sua adesão ao substrato foi avaliada pelo teste de cisalhamento O teste de citocompatibilidade mostrou que o processo de recobrimento por sol-gel não promoveu morte celular significativamente maior que o controle (p > 0,05. Além disso, hastes femorais removidas de pacientes (explantes foram adequadamente recobertas utilizando-se o processo sol-gel.The coating of metallic alloys with bioactive ceramics aims to accelerate bone formation around the implant, contributing to its fixation. In this paper, the deposition of hydroxyapatite ceramic on Ti-6Al-4V alloy sheets by the sol-gel method was studied. The coating layer was characterized by scanning electron microscopy, X-ray diffraction and its adhesion to substrate was evaluated by shear testing. The citocompatibility test shows that the sol-gel coating did not provoke the cell death significantly higher than the control (p > 0.05. Moreover, femoral stems removed from patient (explants were adequately coated using the sol-gel process.

Scratch resistance of SiO2 and SiO2 - ZrO2 sol-gel coatings on glass-ceramic obtained by sintering

International Nuclear Information System (INIS)

Soares, V. O.; Soares, P.; Peitl, O.; Zanotto, E. D.; Duran, A.; Castro, Y.

2013-01-01

The sol-gel process is widely used to obtain coatings on glass-ceramic substrates in order to improve the scratch and abrasion resistance, also providing a bright and homogeneous appearance of a glaze avoiding expensive final polishing treatments. This paper describes the preparation of silica and silica / zirconia coatings by sol-gel method on Li 2 O-Al 2 O3-SiO 2 (LAS) glassceramic substrates produced by sintering. The coatings were deposited by dip-coating on LAS substrates and characterized by optical microscopy and spectral ellipsometry. On the other hand, hardness and elastic modulus, coefficient of friction and abrasion and scratch resistance of the coatings were determined and compared with the substrate properties. Coatings deposited on LAS glass-ceramic confere the substrate a bright and homogeneous aspect, similar to a glaze, improving the appearance and avoiding the final polishing. However these coatings do not increase the scratch resistance of the substrate only equaling the properties of the glass-ceramic. (Author)

Influences of the iron ion (Fe{sup 3+})-doping on structural and optical properties of nanocrystalline TiO{sub 2} thin films prepared by sol-gel spin coating

Energy Technology Data Exchange (ETDEWEB)

Ben Naceur, J. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Bousbih, F.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia)

2011-10-01

Titanium dioxide (TiO{sub 2}) thin films doping of various iron ion (Fe{sup 3+}) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 deg. C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO{sub 2} thin films comprised only the anatase TiO{sub 2}, but the crystallinity decreased when the Fe{sup 3+} content increased from 0% to 20%. During the Fe{sup 3+} addition to 20%, the phase of TiO{sub 2} thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (E{sub g}) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe{sup 3+} content.

Compacting and crystallisation of transparent conductive oxidic sol-gel layers as illustrated by the example of zinc oxide; Verdichtung und Kristallisation von transparenten leitfaehigen oxidischen Sol-gel-Schichten am Beispiel des Zinkoxids

Energy Technology Data Exchange (ETDEWEB)

Schuler, T.

2003-07-01

It is shown that doped zinc oxide films on glass can be obtained by a low-cost sol-gel dip coating process. The lowest possible specific resistance is 1.1x10{sup -3}ohmcm for multiple layers of aluminium-doped zinc oxide. It was shown that for thick layers the crystallite size depends on the doping of the sol, the temperature and the sintering time while the film thickness is largely defined by the concentration (viscosity) of the solution and the drawing time. On this basis, a model of the observed structures was obtained which is also applicable to other sol-gel layers. Using the process parameter p of the equation ESD = p x IKG, the morphology of multiple layers can thus be defined. The structural change from a grain structure to a layered structure was at p = 2.4 to 3 and the transition from layer structure to columnar structure at p = 1. A comparison with spray pyrolysis showed that the suggested model is also suitable as a prototype model for film growth and may possibly applied to physical coating technologies as well. The observed morphology affects the electric and optical properties of the layers, as a result of grain boundaries and compacting. With increasing compacting, the specific resistance of the layer will get lower. It was demonstrated that the coating temperature can be reduced from 550 deg C to 450 deg C without impairing conductivity by reducing the thickness of individual films. Further, possibilities were shown of improving film characteristics or reducing process time by means of other sinter technologies, e.g. pyrolytic gas flame sintering and laser sintering. The biggest problem of sol-gel coating was the segregation of dopands. For all systems, it is assumed that the dopands not converted into (optical) charge carriers will segregate on the surfaces of the crystallites and may even agglomerate into X-ray amorphous oxidic phases if dopand concentrations are high enough. In any case, potential barriers will result which slow down current

Encapsulation of biological species in sol-gel matrices

International Nuclear Information System (INIS)

Finnie, K.S.; Bartlett, J.R.; Woolfrey, J.L.

2000-01-01

Two examples are given of the gelation of silica sols containing bio catalysts, resulting in their encapsulation in porous matrices. Urease was encapsulated in gels made from a mixture of TMOS and alkyltrimethoxysilane. Enzyme activities, monitored by measuring the rate of production of ammoniacal nitrogen as urea was decomposed, ranged up to 60% of that of the unencapsulated species. Anaerobic sulphate-reducing bacteria were encapsulated in a gel produced from colloidal silica, thus avoiding contact with alcohol. The detection of H 2 S produced in the doped gel indicated that the bacteria were able to continue normal metabolic function within the gel matrix. A gel initially doped with ∼ 5 x 10 5 cells cm -3 , exhibited an optimum sulphate reduction rate of 11 ug h -1 cm -3 ; this reduction rate was quickly re-established after storage of the gel for 14 weeks. Copyright (2000) The Australian Ceramic Society

Structural and optical properties of chromium doped zinc oxide nanoparticles synthesized by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Naqvi, Syed Mohd. Adnan, E-mail: adiaks2004@yahoo.co.in [Department of Fundamental and Applied Sciences, Universiti Teknologi Petronas, Bandar Seri Iskandar, Perak (Malaysia); Irshad, Kashif, E-mail: alig.kashif@gmail.com [Department of Mechanical Engineering, Universiti Teknologi Petronas, Bandar Seri Iskandar, Perak (Malaysia); Soleimani, Hassan, E-mail: hassan.soleimani@petronas.com.my, E-mail: noorhana-yahya@petronas.com.my; Yahya, Noorhana, E-mail: hassan.soleimani@petronas.com.my, E-mail: noorhana-yahya@petronas.com.my

2014-10-24

Nanosized Cr-doped ZnO nano particles were synthesized by facile sol-gel auto combustion method. The structural and optical properties of Cr-doped ZnO nanoparticles have been investigated by XRD and UV-Vis spectroscopy at room temperature for 0% to 8% concentration. X-ray diffraction analysis reveals that the Cr-doped ZnO crystallizes in a single phase polycrystalline nature with wurtzite lattice. With every % of doping, the peaks are shifting scarcely and doping of Cr is possible up to 7%. After that, the last peak vanishes, that signifies its structure is transmuted from 8% doping. The average crystallite size decreases with increase in Cr concentration (i.e. 28.9 nm for 0% to 25.8 nm for 8%). The UV-Vis spectra of the nanoparticles betoken an incrementation in the band gap energy from 3.401, 3.415, 3.431, 3.437,3.453, 3.514,3.521, 3.530 and 3.538 eV respectively, for 0,1, 2, 3, 4, 5, 6, 7 and 8 % doping concentration.

Structural and optical properties of chromium doped zinc oxide nanoparticles synthesized by sol-gel method

International Nuclear Information System (INIS)

Naqvi, Syed Mohd. Adnan; Irshad, Kashif; Soleimani, Hassan; Yahya, Noorhana

2014-01-01

Nanosized Cr-doped ZnO nano particles were synthesized by facile sol-gel auto combustion method. The structural and optical properties of Cr-doped ZnO nanoparticles have been investigated by XRD and UV-Vis spectroscopy at room temperature for 0% to 8% concentration. X-ray diffraction analysis reveals that the Cr-doped ZnO crystallizes in a single phase polycrystalline nature with wurtzite lattice. With every % of doping, the peaks are shifting scarcely and doping of Cr is possible up to 7%. After that, the last peak vanishes, that signifies its structure is transmuted from 8% doping. The average crystallite size decreases with increase in Cr concentration (i.e. 28.9 nm for 0% to 25.8 nm for 8%). The UV-Vis spectra of the nanoparticles betoken an incrementation in the band gap energy from 3.401, 3.415, 3.431, 3.437,3.453, 3.514,3.521, 3.530 and 3.538 eV respectively, for 0,1, 2, 3, 4, 5, 6, 7 and 8 % doping concentration

Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol-gel method

International Nuclear Information System (INIS)

Tsay, C.-Y.; Cheng, H.-C.; Tung, Y.-T.; Tuan, W.-H.; Lin, C.-K.

2008-01-01

In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol-gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 deg. C for 10 min and then annealed in air at 500 deg. C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400-600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 x 10 2 Ω-cm

Natamycin based sol-gel antimicrobial coatings on polylactic acid films for food packaging.

Science.gov (United States)

Lantano, Claudia; Alfieri, Ilaria; Cavazza, Antonella; Corradini, Claudio; Lorenzi, Andrea; Zucchetto, Nicola; Montenero, Angelo

2014-12-15

In this work a comprehensive study on a new active packaging obtained by a hybrid organic-inorganic coating with antimicrobial properties was carried out. The packaging system based on polylactic acid was realised by sol-gel processing, employing tetraethoxysilane as a precursor of the inorganic phase and polyvinyl alcohol as the organic component, and incorporating natamycin as the active agent. Films with different organic-inorganic ratios (in a range between 1:19 and 1:4) were prepared, and the amount of antimycotic entrapped was found to be modulated by the sol composition, and was between 0.18 and 0.25mg/dm(2). FTIR microspectroscopic measurements were used to characterise the prepared coatings. The antifungal properties of the films were investigated against mould growth on the surface of commercial semi-soft cheese. The release of natamycin from the films to ethanol 50% (v/v) was studied by means of HPLC UV-DAD. The maximal level released was about 0.105 mg/dm(2), which is far below the value allowed by legislation. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of Ni and Fe doping on YBCO powder prepared by sol gel method

Directory of Open Access Journals (Sweden)

F Saeb

2009-08-01

Full Text Available  We fabricated YBa2Cu3-xMxO7- d (M=Ni, Fe bulk samples, with stochiometric amount 0≤x≤0.045 by sol-gel method. The phase analysis and microstructure of specimens were examined by XRD and SEM. The electrical resistivity was measured using standard four probe technique for 77-300K. Investigation of XRD spectrum by MAUD shows Ni and Fe ions substitute in Cu(2 and Cu(1 site, respectively. Transition temperature decreases in 93-87K for Ni-doped samples and 93-92K for Fe-doped series. It seems that the suppression of superconductivity has no direct correlation with the magnetism of ions itself .

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: bonding to titanium and scanning electron microscopy.

Science.gov (United States)

Tredwin, Christopher J; Georgiou, George; Kim, Hae-Won; Knowles, Jonathan C

2013-05-01

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) production has been characterised and optimised by the sol-gel method and the dissolution and biological properties of these materials were investigated. It was the objective of this study to investigate the potential bond strength and interaction of these materials with titanium. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Using a spin coating technique the sol-gels were coated onto commercially pure titanium disks and crystallised at various temperatures. Using scanning electron microscopy (SEM) and elemental analysis, the surface characteristics, coating thickness and interaction of the Ti substrate and coating were investigated. The bond strengths of the coating to the Ti were investigated using an Instron Universal Load Testing Machine. Statistical analysis was performed with a two-way analysis of variance and post hoc testing with a Bonferroni correction. (1) Coating speed inversely influenced the coating thickness. (2) Increasing fluoride ion substitution and heating temperature significantly increased bond strength and (3) increasing fluoride ion substitution increased the coating thickness. FHA and FA synthesised using the sol-gel technique may offer a superior alternative to coating titanium implants with HA and plasma spraying. HA, FHA and FA materials synthesised by the sol-gel method may also have a use as bone grafting materials. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Homogenous smooth sol gel films doped with organic compounds for nonlinear optics

Energy Technology Data Exchange (ETDEWEB)

Vasiliu, I.C. [INOE 2000 — National Institute for Optoelectronics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Ionita, I., E-mail: i_ionita@yahoo.com [UB — University of Bucharest, 405 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Matei, A. [INFLPR — National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Elisa, M.; Iordanescu, R.; Feraru, I.; Emandi, A. [INOE 2000 — National Institute for Optoelectronics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania)

2016-02-29

The demand for protection of various types of optical sensors from laser-beam pulses has resulted in the search for optical limiting devices that have the property of being transparent at low intensity of light (normal light), but no transparent towards high intensity (laser) light. Organic material with nonlinear optical (NLO) properties as reverse saturable absorption and two-photon absorption can be used for optical limiting with the advantage of a very fast response and self-activation. A promising approach in the fabrication of thin films by low cost/easy use deposition methods for second-order nonlinear optics is sol–gel technique. The present paper reports on the sol–gel synthesis of some pyrazolone derivative doped SiO{sub 2}–P{sub 2}O{sub 5} smooth and homogenous films (Root mean square roughness (Rq) = 1.1 nm) using as precursors tetraethylorthosilicate (TEOS) and phosphoric acid (H{sub 3}PO{sub 4}). The structure of the deposited azo-derivatives doped thin films was examined by Fourier transform infrared spectroscopy and atomic force microscopy, while their optical properties of the films by UV–VIS spectroscopy. The nonlinear optical efficiencies due to the interaction of the NLO-active chromophores with the inorganic matrix have a significant influence on the second harmonic generation capabilities that was measured using a femtosecond Ti:Sapphire laser. The properties of the films were investigated and correlated with the concentration of the organic dopant and the thermal treatment temperature. - Highlights: • We obtained pyrazolone derivative doped SiO{sub 2}–P{sub 2}O{sub 5} smooth and homogenous films. • The pyrazolone derivative presents SHG characteristics by itself. • Thin sol gel films doped with organic compounds with NLO properties. • Temperature of thermal treatment and aging time can improve NLO properties of films. • We found that 150 °C and 28 h aging time give the maximum performance in SHG response.

Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

Science.gov (United States)

Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

2015-02-05

A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results. Copyright © 2014 Elsevier B.V. All rights reserved.

Spectroscopic and electrochemical characterization of cytochrome c encapsulated in a bio sol-gel matrix.

Science.gov (United States)

Deriu, Daniela; Pagnotta, Sara Emanuela; Santucci, Roberto; Rosato, Nicola

2008-08-01

Sol-gel technique represents a remarkably versatile method for protein encapsulation. To enhance sol-gel biocompatibility, systems envisaging the presence of calcium and phosphates in the sol-gel composition were recently prepared and investigated. Unfortunately, the low pH at which solutions were prepared (pH proteins, because the acidic environment induces protein denaturation. In this paper we apply a new protocol based on the introduction of calcium nitrate to the inorganic phase, with formation of a binary bioactive system. In this case protein encapsulation results versatile and secure, being achieved at a pH close to neutrality (pH 6.0); also, the presence of calcium is expected to enhance system biocompatibility. To determine the properties of the salt-doped sol-gel and the influence exerted on entrapped biosystems, the structural and functional properties of embedded cytochrome c have been investigated. Data obtained indicate that the salt-doped sol-gel induces no significant change in the structure and the redox properties of the embedded protein; also, the matrix increases protein stability. Interestingly, the presence of calcium nitrate appears determinant for refolding of the acid-denatured protein. This is of interest in the perspective of future applications in biosensoristic area.

Influence of New Sol-gel Refractory Coating on the Casting Properties of Cold Box and Furan Cores for Grey Cast iron

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Poulsen, T.; Bischoff, C

2010-01-01

New Sol-Gel coated sand cores made from coldbox and furan binder systems were investigated. The idea of the coating was to improve the surface quality of castings. Grey iron was cast on the cores in a sand casting process. The effect of the high temperature of the melt on the cores was assessed...... by measuring the heating curves. The viscosity of the coating, moisture content and the permeability of the cores were evaluated. The surface quality of the castings was investigated using SEM and OM. The results show that the moisture content of the cores affected the permeability. In furan cores the vapour...... transport zone (VTZ) when in contact with the melt is larger than it is in a coldbox which means the furan cores have higher moisture content. The new sol-gel coating has the potential for improving the surface quality of castings without negative effects on the graphite distribution. The surface...

Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

Directory of Open Access Journals (Sweden)

D.V. Sridevi

2017-06-01

Full Text Available A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP and 2–propanol as a common starting material and the obtained products were calcined at 450˚ C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR. The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap.

Sol-gel synthesis of 45S5 bioglass – Prosthetic coating by electrophoretic deposition

Directory of Open Access Journals (Sweden)

Faure Joel

2013-11-01

Full Text Available In this work, the 45S5 bioactive glass has been prepared by the sol-gel process using an organic acid catalyst instead of nitric acid usually used. The physico-chemical and structural characterizations confirmed and validated the elemental composition of the resulting glass. In addition, the 45S5 bioactive glass powder thus obtained was successfully used to elaborate by electrophoretic deposition a prosthetic coating on titanium alloy Ti6Al4V.

Effect of concentrations of plasticizers on the sol-gel properties developed from alkoxides precursors

Energy Technology Data Exchange (ETDEWEB)

Kunst, Sandra Raquel; Longhi, Marielen; Zini, Lucas Pandolphi [Universidade de Caxias do Sul (CCET/UCS), Caxias do Sul, RS (Brazil). Centro de Ciências Exatas e Tecnologia; Beltrami, Lilian Vanessa Rossa; Boniatti, Rosiana; Cardoso, Henrique Ribeiro Piaggio; Vega, Maria Rita Ortega; Malfatti, Célia de Fraga, E-mail: lvrossa@yahoo.com.br [Universidade Federal do Rio Grande do Sul (LAPEC/UFRGS), Porto Alegre, RS (Brazil). Laboratorio de Pesquisa em Corrosão

2017-07-01

Coatings developed through sol-gel method is presented as an interesting replacement to chromium coating. Sol-gel method present advantages as high purity and excellent distribution of the components. The objective of this work is to synthesize and characterize a film obtained by sol-gel route. The film was prepared with 3-(trimethoxysilylpropyl) methacrylate (TMSPMA), tetraethoxysilane (TEOS) and cerium nitrate, using water and ethanol as solvents. Polyethyleneglycol (PEG) plasticizer was added at four different concentrations. The sol was characterized by techniques of viscosity, thermogravimetric analysis (TGA), X-ray diffraction (XRD) nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The results showed that tetrafunctional alkoxides condensation was retarded by the plasticizer, forming a compact film. The film with 20 g.L-1 of PEG showed the best electrochemical behavior. (author)

Photo catalytic Degradation of Organic Dye by Sol-Gel-Derived Gallium-Doped Anatase Titanium Oxide Nanoparticles for Environmental Remediation

International Nuclear Information System (INIS)

Arghya, N.B.; Sang, W.J.; Bong-Ki, M.

2012-01-01

Photo catalytic degradation of toxic organic chemicals is considered to be the most efficient green method for surface water treatment. We have reported the sol-gel synthesis of Gadoped anatase TiO 2 nanoparticles and the photo catalytic oxidation of organic dye into nontoxic inorganic products under UV irradiation. Photodegradation experiments show very good photo catalytic activity of Ga-doped TiO 2 nanoparticles with almost 90% degradation efficiency within 3 hrs of UV irradiation, which is faster than the undoped samples. Doping levels created within the bandgap of TiO 2 act as trapping centers to suppress the photo generated electron-hole recombination for proper and timely utilization of charge carriers for the generation of strong oxidizing radicals to degrade the organic dye. Photo catalytic degradation is found to follow the pseudo-first-order kinetics with the apparent 1 st-order rate constant around 1.3 x 10 -2 min -1 . The cost-effective, sol-gel-derived TiO 2 : Ga nanoparticles can be used efficiently for light-assisted oxidation of toxic organic molecules in the surface water for environmental remediation.

One-step sol-gel imprint lithography for guided-mode resonance structures.

Science.gov (United States)

Huang, Yin; Liu, Longju; Johnson, Michael; C Hillier, Andrew; Lu, Meng

2016-03-04

Guided-mode resonance (GMR) structures consisting of sub-wavelength periodic gratings are capable of producing narrow-linewidth optical resonances. This paper describes a sol-gel-based imprint lithography method for the fabrication of submicron 1D and 2D GMR structures. This method utilizes a patterned polydimethylsiloxane (PDMS) mold to fabricate the grating coupler and waveguide for a GMR device using a sol-gel thin film in a single step. An organic-inorganic hybrid sol-gel film was selected as the imprint material because of its relatively high refractive index. The optical responses of several sol-gel GMR devices were characterized, and the experimental results were in good agreement with the results of electromagnetic simulations. The influence of processing parameters was investigated in order to determine how finely the spectral response and resonant wavelength of the GMR devices could be tuned. As an example potential application, refractometric sensing experiments were performed using a 1D sol-gel device. The results demonstrated a refractive index sensitivity of 50 nm/refractive index unit. This one-step fabrication process offers a simple, rapid, and low-cost means of fabricating GMR structures. We anticipate that this method can be valuable in the development of various GMR-based devices as it can readily enable the fabrication of complex shapes and allow the doping of optically active materials into sol-gel thin film.

Preparation of chitosan-graft-(β-cyclodextrin) based sol-gel stationary phase for open-tubular capillary electrochromatography.

Science.gov (United States)

Lü, Haixia; Li, Qingyin; Yu, Xiaowei; Yi, Jiaojiao; Xie, Zenghong

2013-07-01

A novel open-tubular CEC column coated with chitosan-graft-(β-CD) (CDCS) was prepared using sol-gel technique. In the sol-gel approach, owing to the 3D network of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. The column efficiencies of 55,000∼163,000 plates/m for the isomeric xanthopterin and phenoxy acid herbicides using the sol-gel-derived CDCS columns were achieved. Good stabilities were demonstrated that the RSD values for the retention time of thiourea and isoxanthopterin were 1.3 and 1.4% (run to run, n = 5), 1.6 and 2.0% (day to day, n = 3), 2.9 and 3.1% (column to column, n = 3), respectively. The sol-gel-coated CDCS columns have shown improved separations of isomeric xanthopterin in comparison with CDCS-bonded capillary column. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gamma ray irradiation induced optical band gap variations in silica sol-gel doped sucrose

International Nuclear Information System (INIS)

Marzouki, F.; Farah, K.; Hamzaoui, A.H; Ben Ouada, H

2015-01-01

The silica xerogels doped sucrose was prepared via sol-gel process and exposed at room temperature to different doses of high energy ("6"0Co) gamma irradiation. Changes in the UV-visible and FTIR spectra of pristine and irradiated xerogels with varying of gamma doses rays show variation in the gap energy. It was found that energy gap of the investigated silica xerogels decreases with increasing the gamma irradiation doses. Thereby the irradiated samples reveal behaviour changes, from an insulator (Eg ∼5,8 eV) towards a semiconductor with (Eg ∼ 3.5 eV).

Quantum dot based on tin/titanium mixed oxide doped with europium synthesized by protein sol-gel method

International Nuclear Information System (INIS)

Paganini, Paula P.; Felinto, Maria Claudia F.C.; Brito, Hermi F.

2011-01-01

Special luminescence biomarkers have been developed to find more sensitive fluoroimmunoassay methods. A new generation of these biomarkers is the semiconductors nanocrystals, known as quantum dots, doped with lanthanides. The use of lanthanides ions as luminescent markers has many advantages, for example a security method, low cost, high specificity and also the luminescence can be promptly measured with high sensibility and accuracy. The protein sol-gel is a modification of conventional method, in which the coconut water replacing the alkoxides normally used. The advantage is that, the proteins present in coconut water bind chemically with metal salts forming a polymer chain. This work presents nanoparticles based on tin/titanium mixed oxide doped with 3% of europium synthesized by protein sol-gel method. The nanoparticles were burned at 300 deg C, 500 deg C, 800 deg C and 1100 deg C. The samples were analyzed and characterized by thermal analysis, X-ray powder diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The synthesis was effective and the nanoparticles showed nanometric size and structural differences with the annealing. To be used in the fluoroimmunoassays tests, these particles need to be functionalized before be connect with biological molecules and after this process, these nanoparticles going to be submitted at gamma radiation for sterilization. (author)

Quantum dot based on tin/titanium mixed oxide doped with europium synthesized by protein sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Paganini, Paula P.; Felinto, Maria Claudia F.C., E-mail: paulapaganini@usp.b, E-mail: mfelinto@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Brito, Hermi F., E-mail: hefbrito@iq.usp.b [Universidade de Sao Paulo (IQ/USP), Sao Paulo, SP (Brazil). Inst. de Quimica. Lab. de Elementos do Bloco f

2011-07-01

Special luminescence biomarkers have been developed to find more sensitive fluoroimmunoassay methods. A new generation of these biomarkers is the semiconductors nanocrystals, known as quantum dots, doped with lanthanides. The use of lanthanides ions as luminescent markers has many advantages, for example a security method, low cost, high specificity and also the luminescence can be promptly measured with high sensibility and accuracy. The protein sol-gel is a modification of conventional method, in which the coconut water replacing the alkoxides normally used. The advantage is that, the proteins present in coconut water bind chemically with metal salts forming a polymer chain. This work presents nanoparticles based on tin/titanium mixed oxide doped with 3% of europium synthesized by protein sol-gel method. The nanoparticles were burned at 300 deg C, 500 deg C, 800 deg C and 1100 deg C. The samples were analyzed and characterized by thermal analysis, X-ray powder diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The synthesis was effective and the nanoparticles showed nanometric size and structural differences with the annealing. To be used in the fluoroimmunoassays tests, these particles need to be functionalized before be connect with biological molecules and after this process, these nanoparticles going to be submitted at gamma radiation for sterilization. (author)

Physical properties and heterojunction device demonstration of aluminum-doped ZnO thin films synthesized at room ambient via sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Karaagac, Hakan, E-mail: hkaraagac@ucdavis.edu [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States); Yengel, Emre; Saif Islam, M. [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States)

2012-04-25

Highlights: Black-Right-Pointing-Pointer Undoped and Al doped ZnO (AZO) thin films were successfully prepared using sol-gel technique. Black-Right-Pointing-Pointer Structural analysis has revealed that Al doping has a significant influence on preferential orientation. Black-Right-Pointing-Pointer It has been observed that wrinkles forms on the surface of films when annealed with a fast heat ramp up rate. Black-Right-Pointing-Pointer Optical analysis has revealed that that the band gap energy of ZnO thin film increases with increasing Al doping concentration. Black-Right-Pointing-Pointer The lowest resistivity is observed for 1% Al ZnO thin film, which is 2.2 Multiplication-Sign 10{sup -2} ({Omega} cm). - Abstract: ZnO and some of its ternary wide-bandgap alloys offer interesting opportunities for designing materials with tunable band gaps, strong piezoresistivity and controlled electrical conductance with high optical transparency. Synthesizing these materials on arbitrary substrates using low-cost and unconventional techniques can help in integrating semiconductors with different physical, electrical, and optical characteristics on a single substrate for heterogeneous integration of multifunctional devices. Here we report the successful synthesis of aluminum (Al) doped ZnO (AZO) thin films on soda-lime glass, silicon and fluorine doped tin oxide (FTO) pre-coated glass substrates by using sol-gel deposition method at ambient condition. X-ray diffraction (XRD) analysis revealed that varying degree of Al doping significantly impacts the crystal orientation, semiconductor bandgap and optical transparency of the film. Crystal structure of the film is also found to be strongly correlated to the characteristics of the substrate material. The impact of heating rate during post annealing process is studied and optimized in order to improve the surface morphology of the deposited films. Optical characterizations have revealed that bandgap energy of AZO films can be tuned

Fabrication and electrical resistivity of Mo-doped VO2 thin films coated on graphite conductive plates by a sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Choi, W.; Jung, H.M.; Um, S. [Hanyang Univ., Seoul (Korea, Republic of). School of Mechanical Engineering

2008-07-01

Vanadium oxides (VO2) can be used in optical devices, thermochromic smart windows and sensors. This paper reported on a study in which vanadium pentoxide (V2O5) powder was prepared and mixed with Molybdenum Oxides (MoO3) to form Mo-doped and -undoped VO2 thin films by a sol-gel method on graphite conductive substrates. The micro-structure and chemical compositions of the Mo-doped and -undoped VO2 thin films was investigated using X-Ray diffraction and scanning electron microscopy. Changes in electrical resistivity were measured as a function of the stoichiometric compositions between vanadium and molybdenum. In this study. Mo-doped and -undoped VO2 thin films showed the typical metal to insulator transition (MIT), where temperature range could be adjusted by modifying the dopant atomic ratio. The through-plane substrate structure of the Mo-doped layer influences the electrical resistivity of the graphite substrate. As the amount of the molybdenum increases, the electrical resistivity of the graphite conductive substrate decreases in the lower temperature range below the freezing point of water. The experimental results showed that if carefully controlled, thermal dissipation of VO2 thin films can be used as a self-heating source to melt frozen water with the electrical current flowing through the graphite substrate. 3 refs., 3 figs.

Effect of concentrations of plasticizers on the sol-gel properties developed from alkoxides precursors

Directory of Open Access Journals (Sweden)

Sandra Raquel Kunst

Full Text Available Abstract Coatings developed through sol-gel method is presented as an interesting replacement to chromium coating. Sol-gel method present advantages as high purity and excellent distribution of the components. The objective of this work is to synthesize and characterize a film obtained by sol-gel route. The film was prepared with 3-(trimethoxysilylpropyl methacrylate (TMSPMA, tetraethoxysilane (TEOS and cerium nitrate, using water and ethanol as solvents. Polyethyleneglycol (PEG plasticizer was added at four different concentrations. The sol was characterized by techniques of viscosity, thermogravimetric analysis (TGA, X-ray diffraction (XRD nuclear magnetic resonance spectroscopy (NMR and Fourier transform infrared spectroscopy (FT-IR. The results showed that tetrafunctional alkoxides condensation was retarded by the plasticizer, forming a compact film. The film with 20 g.L-1 of PEG showed the best electrochemical behavior.

Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites

Directory of Open Access Journals (Sweden)

T. Sakthivel

2017-06-01

Full Text Available Pure and Ni doped titanium dioxide nanoparticles were successfully synthesized by sol-gel method and characterized usingXRD, UV-Visible, FTIR, FESEM and EDS techniques. XRD pattern confirms the formation of tetragonal TiO2. The absorbance spectra of pure and Ni doped TiO2 showed absorption spectrum at ultra-violet region due to electronic transition between bonding and anti-bonding orbital (π-π•. Bandgap energy of Ni doped TiO2 decreased to 2.5 eV when compared to pure TiO2 (3.39 eV. FESEM study reveals agglomerated spherical shaped morphology. The functional groups of the prepared samples were identified using FTIR spectroscopy and the elemental analysis was further supported with EDS analysis.

Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

International Nuclear Information System (INIS)

Crespo, M.A. Dominguez; Murillo, A. Garcia; Torres-Huerta, A.M.; Yanez-Zamora, C.; Carrillo-Romo, F. de J

2009-01-01

Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr 6+ has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y 2 O 3 ) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y 2 O 3 coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.

Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Crespo, M.A. Dominguez, E-mail: mdominguezc@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Murillo, A. Garcia; Torres-Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Yanez-Zamora, C. [Estudiante del postgrado en Tecnologia Avanzada del CICATA-IPN, Unidad Altamira, km 14.5, Carr. Tampico-Puerto Industrial. C.P. 89600, Altamira, Tamaulipas (Mexico); Carrillo-Romo, F. de J [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico)

2009-08-26

Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr{sup 6+} has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y{sub 2}O{sub 3}) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y{sub 2}O{sub 3} coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.

Preparation and studies of Eu{sup 3+} and Tb{sup 3+} co-doped Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3} sol-gel scintillating films

Energy Technology Data Exchange (ETDEWEB)

Morales Ramirez, A. de J, E-mail: amoralesra@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA) Unidad Altamira Instituto Politecnico Nacional Km. 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico); Garcia Murillo, A.; Carrillo Romo, F. de J [Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico); Ramirez Salgado, J. [Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas No. 152, CP 07730, Mexico D.F. (Mexico); Le Luyer, C. [LPCML, CNRS-UMR 5620/Universite Claude Bernard Lyon 1/69622 Villeurbanne Cedex (France); Chadeyron, G.; Boyer, D. [Laboratoire des Materiaux Inorganiques, CNRS-UMR 6002, Universite Blaise Pascal, 24 Ave des Landais F 63177 Aubiere Cedex (France); Moreno Palmerin, J. [Depto. de Ingenieria Metalurgica, ESIQIE-Instituto Politecnico Nacional UPALM C.P. 07738, Mexico D.F. (Mexico)

2009-10-30

Eu{sup 3+} (2.5 at.%) and Tb{sup 3+} (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3}) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 {sup o}C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm {+-} 0.2 (A = 0.0075 Tb{sup 3+}) and 24 nm {+-} 3.0 (B = 0.01 Tb{sup 3+}). After treatment at 700 {sup o}C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu{sup 3+}- and Tb{sup 3+}-doped Gd{sub 2}O{sub 3} and Y{sub 2}O{sub 3} powders showed that Tb{sup 3+} contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb{sup 3+} concentrations (down to 0.005 at.%) in both systems enhanced the light yield.

Synthesis and characterization of uniform silica nanoparticles on nickel substrate by spin coating and sol-gel method

Science.gov (United States)

Ngoc Thi Le, Hien; Jeong, Hae Kyung

2014-01-01

Spin coating and sol-gel methods are proposed for the preparation of silica nanoparticles on a nickel substrate using silicon tetrachloride, 2-methoxyethanol, and four different types of alkaline solutions. The effects of the type of alkaline solution, concentration of silica solution, and speed of spin coating on the properties of silica nanoparticles are investigated systematically. Uniform spherical shape of silica nanoparticles on Ni with the smallest size are obtained with sodium carbonate among the alkaline solutions after stirring at 70 °C for 6 h and spin-coating at 7000 rpm. Physical and electrochemical properties of the silica particles are investigated.

Thermal Annealing Effect on Optical Properties of Binary TiO2-SiO2 Sol-Gel Coatings

Directory of Open Access Journals (Sweden)

Xiaodong Wang

2012-12-01

Full Text Available TiO2-SiO2 binary coatings were deposited by a sol-gel dip-coating method using tetrabutyl titanate and tetraethyl orthosilicate as precursors. The structure and chemical composition of the coatings annealed at different temperatures were analyzed by Raman spectroscopy and Fourier Transform Infrared (FTIR spectroscopy. The refractive indices of the coatings were calculated from the measured transmittance and reflectance spectra. An increase in refractive index with the high temperature thermal annealing process was observed. The Raman and FTIR results indicate that the refractive index variation is due to changes in the removal of the organic component, phase separation and the crystal structure of the binary coatings.

Magnetic studies of cobalt doped barium hexaferrite nanoparticles prepared by modified sol-gel method

International Nuclear Information System (INIS)

Shalini, M. Govindaraj; Sahoo, Subasa C.

2016-01-01

M-type barium hexaferrite (BaFe_1_2O_1_9) and cobalt doped barium hexaferrite (BaFe_1_1CoO_1_9) nanopowders were synthesized by modified sol-gel auto-combustion technique and were annealed at 900°C in air for 4 hours. The annealed powders were studied in the present work and X-ray diffraction studies showed pure phase formation after annealing. The average grain size in the nanopowder sample was decreased after doping. Magnetization value of 60 emu/g was observed at 300 K for the barium hexaferrite and was reduced to 54 emu/g after doping. The coercivity of 5586 Oe was observed at 300 K for the undoped sample and was found to be decreased in the doped sample. As the measurement temperature was decreased from 300 K to 60 K, magnetization value was increased in both the samples compared to those at 300 K. The coercivity of the undoped sample was found to decrease whereas it was increased for the doped sample at 60 K. The observed magnetic properties may be understood on the basis of modified exchange interaction and anisotropy in the doped sample compared to that of pure barium hexaferrite.

Sol-gel processes. January 1970-September 1989 (Citations from the NTIS data base). Report for January 1970-September 1989

International Nuclear Information System (INIS)

1989-09-01

This bibliography contains citations concerning the development and utilization of sol-gel processes and techniques. Topics include antireflective coatings, studies of sol-gel transitions, sol-gel synthesis and polymerization, sol-gel derived thin films and glasses, and sol-gel production of microspheres. Applications in nuclear waste management, nuclear-fuel manufacturing, glass optical waveguide development, and solar-energy collection are presented. (This updated bibliography contains 179 citations, 39 of which are new entries to the previous edition.)

Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Directory of Open Access Journals (Sweden)

Liang Jiang

2017-12-01

Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

PREPARATION OF TITANIA SOL-GEL COATINGS CONTAINING SILVER IN VARIOUS FORMS AND MEASURING OF THEIR BACTERICIDAL EFFECTS AGAINST E. COLI

Directory of Open Access Journals (Sweden)

Diana Horkavcova

2015-09-01

Full Text Available The work describes titania coatings containing various forms of silver applied on a titanium substrate by a dip-coating sol-gel technique. Silver was added into the basic titania sol in form of colloid particles of Ag, crystals of AgNO3, particles of AgI, particles of Ag3PO4 and Ag3PO4 developed in situ (in the sol by reaction of AgNO3 with added calcium phosphate (brushite or monetite. Mechanically and chemically treated titanium substrates were dipped at a constant rate into individual types of sols. Subsequently, they were slowly fired. The fired coatings contained microcracks. All over the surface there were evenly distributed spherical nanoparticles of silver (Ag, AgNO3 or microcrystals of AgI and Ag3PO4. The prepared coatings were tested under static conditions for their bactericidal effects against gram-negative bacteria Escherichia coli (E. coli. The coated substrates were immersed into a suspension of E. coli in physiological solution for 24 and 4 hours. The basic titania coatings with no silver demonstrated no bactericidal properties. Very good bactericidal effect against E. coli in both types of bactericidal test showed the titania coatings with AgNO3, Ag3PO4 crystals and Ag3PO4 developed in situ.

Reversible sol-gel-sol medium for enzymatic optical biosensors

NARCIS (Netherlands)

Safaryan, S.; Yakovlev, A.; Pidko, E.A.; Vinogradov, A.; Vinogradov, V.

2017-01-01

In this paper we for the first time report a reversible sol-gel-sol approach to obtain optical enzymatic biosensors with improved enzyme stability and good sensitivity by using desktop inkjet printing. The developed technique is based on the bio-inorganic inks allowing for a sol-gel-sol transition

Poly(aniline) nanowires in sol-gel coated ITO: A pH-responsive substrate for planar supported lipid bilayers

Science.gov (United States)

Ge, Chenhao; Orosz, Kristina S.; Armstrong, Neal R.; Saavedra, S. Scott

2011-01-01

Facilitated ion transport across an artificial lipid bilayer coupled to a solid substrate is a function common to several types of bioelectronic devices based on supported membranes, including biomimetic fuel cells and ion channel biosensors. Described here is fabrication of a pH-sensitive transducer composed of a porous sol-gel layer derivatized with poly(aniline) (PANI) nanowires grown from an underlying planar indium-tin oxide (ITO) electrode. The upper sol-gel surface is hydrophilic, smooth, and compatible with deposition of a planar supported lipid bilayer (PSLB) formed via vesicle fusion. Conducting tip AFM was used to show that the PANI wires are connected to the ITO, which convert this electrode into a potentiometric pH sensor. The response to changes in the pH of the buffer contacting the PANI nanowire/sol-gel/ITO electrode is blocked by the very low ion permeability of the overlying, fluid PSLB. The feasibility of using this assembly to monitor facilitated proton transport across the PSLB was demonstrated by doping the membrane with lipophilic ionophores that respond to a transmembrane pH gradient, which produced an apparent proton permeability several orders of magnitude greater than values measured for undoped lipid bilayers. PMID:21707069

Sol-gel deposition and electrical properties of laser irradiated Cu doped TiO2 multilayer thin films

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available Multilayer thin films (3, 5 and 7 of 20% copper doped titanium dioxide (Cu:TiO2 have been deposited on glass substrates by sol-gel spin coating method. After deposition, films have been irradiated by a beam of continuous wave diode laser (532 nm for two minutes at the angle of 45°. Structural, surface morphology and electrical properties of films have been investigated by X-rays diffraction (XRD, scanning electron microscope (SEM and four point probe technique respectively. XRD shows the formation of titanium copper oxide. Surface morphology of thin films indicated that the average grain size is increased by increasing the number of layers. The average sheet resistivity of 3, 5 and 7 layers of thin films measured by four point probe technique is 2.2 × 104, 1.2 × 104 and 1.0 × 104 (Ohm-cm respectively. The present study will facilitate a cost effective and environmental friendly study for several properties of materials. Keywords: Cu:TiO2, Multilayer thin films, Diode laser

Surface functionalization of carbon nanofibers by sol-gel coating of zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Shao Dongfeng [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China); Changzhou Textile Garment Institute, Changzhou 213164 (China); Wei Qufu [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)], E-mail: qfwei@jiangnan.edu.cn; Zhang Liwei; Cai Yibing; Jiang Shudong [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)

2008-08-15

In this paper the functional carbon nanofibers were prepared by the carbonization of ZnO coated PAN nanofibers to expand the potential applications of carbon nanofibers. Polyacrylonitrile (PAN) nanofibers were obtained by electrospinning. The electrospun PAN nanofibers were then used as substrates for depositing the functional layer of zinc oxide (ZnO) on the PAN nanofiber surfaces by sol-gel technique. The effects of coating, pre-oxidation and carbonization on the surface morphology and structures of the nanofibers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM), respectively. The results of SEM showed a significant increase of the size of ZnO nanograins on the surface of nanofibers after the treatments of coating, pre-oxidation and carbonization. The observations by SEM also revealed that ZnO nanoclusters were firmly and clearly distributed on the surface of the carbon nanofibers. FTIR examination also confirmed the deposition of ZnO on the surface of carbon nanofibers. The XRD analysis indicated that the crystal structure of ZnO nanograins on the surface of carbon nanofibers.

In vitro toxicity assessment of extracts derived from sol-gel coatings on polycarbonate intended to be used in food contact applications.

Science.gov (United States)

Séverin, Isabelle; Lionti, Krystelle; Dahbi, Laurence; Loriot, Catherine; Toury, Bérangère; Chagnon, Marie-Christine

2016-07-01

Polycarbonate is a widely used polymer in food contact applications all around the world. However, due to the potential release of Bisphenol A (BPA) during repeated washing cycles, its use becomes compromised as BPA is known for being an endocrine disruptor for rodents. In order to tackle this issue, sol-gel coatings based on organoalkoxysiloxane were developed on PC, to act as a physical barrier. To this end, two sol-gel systems based on tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES) and 3-glycidyloxypropyltriethoxysilane (GPTES), three common sol-gel precursors, were prepared. The coatings derived from the latter two systems were then studied with regards to their potential toxicity in vitro. Migration tests were performed in food simulants, and the maximal migration was obtained in ethanol 10% (v/v) for one system and in isooctane for the other one. In vitro genotoxicity was assessed with the Ames test (OECD 471) and the micronucleus assay (OECD 487), and no genotoxic effect was observed. Moreover, the estrogenic activity of the extracts was studied with a transcriptional activation assay using transient transfection in human cells; none of the extracts was found estrogenic. These negative in vitro results are highly promising for the future use of these new barrier coating formulations onto food contact materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method. Optimisation, characterisation and rheology.

Science.gov (United States)

Tredwin, Christopher J; Young, Anne M; Georgiou, George; Shin, Song-Hee; Kim, Hae-Won; Knowles, Jonathan C

2013-02-01

Currently, most titanium implant coatings are made using hydroxyapatite and a plasma spraying technique. There are however limitations associated with plasma spraying processes including poor adherence, high porosity and cost. An alternative method utilising the sol-gel technique offers many potential advantages but is currently lacking research data for this application. It was the objective of this study to characterise and optimise the production of Hydroxyapatite (HA), fluorhydroxyapatite (FHA) and fluorapatite (FA) using a sol-gel technique and assess the rheological properties of these materials. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethylphosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the sol-gel derived FHA and FA. Optimisation of the chemistry and subsequent characterisation of the sol-gel derived materials was carried out using X-ray Diffraction (XRD) and Differential Thermal Analysis (DTA). Rheology of the sol-gels was investigated using a viscometer and contact angle measurement. A protocol was established that allowed synthesis of HA, FHA and FA that were at least 99% phase pure. The more fluoride incorporated into the apatite structure; the lower the crystallisation temperature, the smaller the unit cell size (changes in the a-axis), the higher the viscosity and contact angle of the sol-gel derived apatite. A technique has been developed for the production of HA, FHA and FA by the sol-gel technique. Increasing fluoride substitution in the apatite structure alters the potential coating properties. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Development of novel Sol-Gel Indicators (SGI's) for in-situ environmental measurements: Part 1, Program and a new pH Sol-Gel Indicator

International Nuclear Information System (INIS)

Livingston, R.R.; Baylor, L.; Wicks, G.G.

1992-01-01

The feasibility of incorporating analytical indicators into a sol-gel glassy matrix and then coating substrates with this composite material has bee demonstrated. Substrates coated include paper, wood, glass, and the lens of an analytical probe. The first SRTC sol-gel indicator, comprising bromophenol blue dispersed in a silica matrix, was fabricated and successfully used to measure solution pH in the range of pH 3.0 to 7.5. material exhibited a quick response time, as measured by color changes both qualitatively and quantitatively, and the measuring device was reversible or reusable. Additional indicators with responses over other ranges as well as indicators sensitive to the presence of elements of interest, are also under development. The new SGI composites possess promising properties and an excellent potential for performing a variety important in-situ environmental measurements and area discussed in this report

Improvement of Adhesion Properties and Corrosion Resistance of Sol-Gel Coating on Zinc.

Science.gov (United States)

Savignac, Pauline; Menu, Marie-Joëlle; Gressier, Marie; Denat, Bastien; Khadir, Yacine El; Manov, Stephan; Ansart, Florence

2018-05-03

Corrosion is a major problem for durability of many metals and alloys. Among the efficient classical surface treatments, chromate-based treatments must be banished from industrial use due to their toxicity. At the same time, sol-gel routes have demonstrated high potential to develop an efficient barrier effect against aggressive environments. By this process, the anti-corrosion property can be also associated to others in the case of the development of multi-functional hybrid coatings. In this paper, the main goal is precisely to improve both the corrosion resistance and the adhesion properties of phosphated zinc substrates by the deposition of a hybrid (organic-inorganic) sol-gel layer. To reach this double objective, a choice between two formulations 3-glycidoxypropyltrimethoxysilane (GPTMS)/aluminum-tri-sec-butoxide (ASB) and 3-(trimethoxysilyl)propylmethacrylate (MAP)/tetraethylorthosilicate (TEOS) was firstly made based on the results obtained by microstructural characterizations using SEM, optical analysis, and mechanical characterization such as shock and/or scratch tests (coupled to climatic chamber and salt spray exposure). Several investigations were performed in this study, and the best formulation and performances of the system were obtained by adding a new precursor (1-[3-(trimethoxysilyl)propyl]ureido-UPS) under controlled conditions, as detailed in this paper.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim; El Ghoul, Jaber; Lemine, O. M.; Bououdina, M.; Zhang, Bei; El Mir, Lassaad

2013-01-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim

2013-08-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Sol-gel applications for ceramic membrane preparation

Science.gov (United States)

Erdem, I.

2017-02-01

Ceramic membranes possessing superior properties compared to polymeric membranes are more durable under severe working conditions and therefore their service life is longer. The ceramic membranes are composed of some layers. The support is the layer composed of coarser ceramic structure and responsible for mechanical durability under filtration pressure and it is prepared by consolidation of ceramic powders. The top layer is composed of a finer ceramic micro-structure mainly responsible for the separation of components present in the fluid to be filtered and sol-gel method is a versatile tool to prepare such a tailor-made ceramic filtration structure with finer pores. Depending on the type of filtration (e.g. micro-filtration, ultra-filtration, nano-filtration) aiming separation of components with different sizes, sols with different particulate sizes should be prepared and consolidated with varying precursors and preparation conditions. The coating of sol on the support layer and heat treatment application to have a stable ceramic micro-structure are also important steps determining the final properties of the top layer. Sol-gel method with various controllable parameters (e.g. precursor type, sol formation kinetics, heat treatment conditions) is a practical tool for the preparation of top layers of ceramic composite membranes with desired physicochemical properties.

Epitaxial growth of Er, Ti doped LiNbO3 films prepared by sol-gel method

International Nuclear Information System (INIS)

Takahashi, Makoto; Yoshiga, Tsuyoshi; Kajitani, Naofumi; Takeda, Yuki; Sato, Shoji; Wakita, Koichi; Ohnishi, Naoyuki; Hotta, Kazutoshi; Kurachi, Masato

2006-01-01

Erbium (Er 3+ ) doped lithium niobate (LiNbO 3 ) thick films were deposited on z-cut congruent LiNbO 3 (LN) substrate by the sol-gel method from the 0.20 mol/dm 3 precursor solution containing various Er 3+ concentration and 0.10 mol/dm 3 poly(vinyl alcohol) (PVA), and their crystal characteristics were evaluated. The Er 3+ concentration in the LN film was controlled by the Er 3+ concentration in the starting solution. The orientation relationships between Er doped LN films and substrates were determined by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy, and (006) oriented Er doped LN epitaxial layers with parallel epitaxial relationships could be grown on the z-cut LN wafer. Moreover, it was made clear from the electron beam diffraction measurements that the film came to be polycrystalline, when the Er concentration was over 3 mol%. The refractive index of Er-doped LN films decreased with increasing Er concentration. 1.5 mol% Ti: 1.0 mol% Er LN films, which acted as a waveguide, were prepared by our so-gel method. It showed the 1530 nm emission by 980 nm excitation, which was considered to be due to the Er 3+ corresponding to the 4 I 13/2 → 4 I 15/2 transition. (author)

Controlled release of vancomycin from thin sol-gel films on implant surfaces successfully controls osteomyelitis.

Science.gov (United States)

Adams, Christopher S; Antoci, Valentin; Harrison, Gerald; Patal, Payal; Freeman, Terry A; Shapiro, Irving M; Parvizi, Javad; Hickok, Noreen J; Radin, Shula; Ducheyne, Paul

2009-06-01

Peri-prosthetic infection remains a serious complication of joint replacement surgery. Herein, we demonstrate that a vancomycin-containing sol-gel film on Ti alloy rods can successfully treat bacterial infections in an animal model. The vancomycin-containing sol-gel films exhibited predictable release kinetics, while significantly inhibiting S. aureus adhesion. When evaluated in a rat osteomyelitis model, microbiological analysis indicated that the vancomycin-containing sol-gel film caused a profound decrease in S. aureus number. Radiologically, while the control side showed extensive bone degradation, including abscesses and an extensive periosteal reaction, rods coated with the vancomycin-containing sol-gel film resulted in minimal signs of infection. MicroCT analysis confirmed the radiological results, while demonstrating that the vancomycin-containing sol-gel film significantly protected dense bone from resorption and minimized remodeling. These results clearly demonstrate that this novel thin sol-gel technology can be used for the targeted delivery of antibiotics for the treatment of periprosthetic as well as other bone infections. Copyright 2008 Orthopaedic Research Society

Carbamazepine degradation using a N-doped TiO_2 coated photocatalytic membrane reactor: Influence of physical parameters

International Nuclear Information System (INIS)

Horovitz, Inna; Avisar, Dror; Baker, Mark A.; Grilli, Rossana; Lozzi, Luca; Di Camillo, Daniela; Mamane, Hadas

2016-01-01

Highlights: • UV–vis N-doped TiO_2 was deposited by sol-gel onto Al_2O_3 microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al_2O_3 membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO_2 vs. non-doped TiO_2 membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al_2O_3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO_2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO_2 films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO_2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO_2-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

Nanocrystal/sol-gel nanocomposites

Science.gov (United States)

Petruska, Melissa A [Los Alamos, NM; Klimov, Victor L [Los Alamos, NM

2007-06-05

The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.

Active corrosion protection of AA2024 by sol-gel coatings with corrosion inhibitors =

Science.gov (United States)

Yasakau, Kiryl

A industria aeronautica utiliza ligas de aluminio de alta resistencia para o fabrico dos elementos estruturais dos avioes. As ligas usadas possuem excelentes propriedades mecanicas mas apresentam simultaneamente uma grande tendencia para a corrosao. Por esta razao essas ligas necessitam de proteccao anticorrosiva eficaz para poderem ser utilizadas com seguranca. Ate a data, os sistemas anticorrosivos mais eficazes para ligas de aluminio contem cromio hexavalente na sua composicao, sejam pre-tratamentos, camadas de conversao ou pigmentos anticorrosivos. O reconhecimento dos efeitos carcinogenicos do cromio hexavalente levou ao aparecimento de legislacao banindo o uso desta forma de cromio pela industria. Esta decisao trouxe a necessidade de encontrar alternativas ambientalmente inocuas mas igualmente eficazes. O principal objectivo do presente trabalho e o desenvolvimento de pretratamentos anticorrosivos activos para a liga de aluminio 2024, baseados em revestimentos hibridos produzidos pelo metodo sol-gel. Estes revestimentos deverao possuir boa aderencia ao substrato metalico, boas propriedades barreira e capacidade anticorrosiva activa. A proteccao activa pode ser alcancada atraves da incorporacao de inibidores anticorrosivos no pretratamento. O objectivo foi atingido atraves de uma sucessao de etapas. Primeiro investigou-se em detalhe a corrosao localizada (por picada) da liga de aluminio 2024. Os resultados obtidos permitiram uma melhor compreensao da susceptibilidade desta liga a processos de corrosao localizada. Estudaram-se tambem varios possiveis inibidores de corrosao usando tecnicas electroquimicas e microestruturais. Numa segunda etapa desenvolveram-se revestimentos anticorrosivos hibridos organico-inorganico baseados no metodo sol-gel. Compostos derivados de titania e zirconia foram combinados com siloxanos organofuncionais a fim de obter-se boa aderencia entre o revestimento e o substrato metalico assim como boas propriedades barreira. Testes

Highly efficient solid-state neutron scintillators based on hybrid sol-gel nanocomposite materials

International Nuclear Information System (INIS)

Kesanli, Banu; Hong, Kunlun; Meyer, Kent; Im, Hee-Jung; Dai, Sheng

2006-01-01

This research highlights opportunities in the formulation of neutron scintillators that not only have high scintillation efficiencies but also can be readily cast into two-dimensional detectors. Series of transparent, crack-free monoliths were prepared from hybrid polystyrene-silica nanocomposites in the presence of arene-containing alkoxide precursor through room temperature sol-gel processing. The monoliths also contain lithium-6 salicylate as a target material for neutron-capture reactions and amphiphilic scintillator solution as a fluorescent sensitizer. Polystyrene was functionalized by trimethoxysilyl group in order to enable the covalent incorporation of aromatic functional groups into the inorganic sol-gel matrices for minimizing macroscopic phase segregation and facilitating lithium-6 doping in the sol-gel samples. Neutron and alpha responses of these hybrid polystyrene-silica monoliths were explored

Proteic sol-gel synthesis of copper doped misfit Ca-cobaltites with potential SOFC application

Energy Technology Data Exchange (ETDEWEB)

Lima, Chrystian G.M. [Materials Science and Engineering Postgraduate Program, UFPB, 58051-900, João Pessoa (Brazil); Silva, Rinaldo M. [Department of Chemical Engineering, UFPB, 58051-900, João Pessoa (Brazil); Aquino, Flávia de M. [Alternative and Renewable Energy Center, UFPB, 58051-900, João Pessoa (Brazil); Raveau, Bernard; Caignaert, Vincent [Laboratoire CRISMAT ENSICAEN UMR CNRS 6508, 6 Boulevard du Maréchal Juin, 14050, Caen Cedex 04 (France); Cesário, Moisés R., E-mail: moises.cesario@ensicaen.fr [Laboratoire CRISMAT ENSICAEN UMR CNRS 6508, 6 Boulevard du Maréchal Juin, 14050, Caen Cedex 04 (France); Macedo, Daniel A., E-mail: damaced@gmail.com [Materials Science and Engineering Postgraduate Program, UFPB, 58051-900, João Pessoa (Brazil)

2017-02-01

The present work reports the synthesis, structure and electrochemical assessment of Cu-doped calcium cobaltites as cathode materials for solid oxide fuel cells (SOFCs). Powders of composition Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} (0 ≤ x ≤ 0.2) were obtained by a proteic sol-gel method which uses gelatin as polymerizing agent. As-prepared materials were calcined at 900 °C for 1 h and characterized by X-ray diffraction, with Rietveld refinement of the diffraction data, and scanning electron microscopy. Screen-printed porous electrodes fired (at 950 °C for 2 h) on both faces of ceria based electrolytes were electrochemically characterized by impedance spectroscopy between 600 and 800 °C in air atmosphere. The results indicated the attainment of Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} solid solutions with monoclinic misfit layered structure and around 2 vol% Co{sub 3}O{sub 4} as a secondary phase. Micro-plates like powders had irregular shape and average diameter near 2 μm. The area specific resistance (ASR) is in line with literature data for cathodes of similar compositions prepared by other synthetic routes. ASR was optimized for the composition Ca{sub 2.99}Cu{sub 0.01}Co{sub 4}O{sub 9−δ}, achieving 0.84 Ω cm{sup 2} at 800 °C in air. - Highlights: • Proteic sol-gel synthesis of Ca{sub 3−x}Cu{sub x}Co{sub 4}O{sub 9−δ} (0 ≤ x ≤ 0.2). • Cu{sup 2+} doping enhances electrode densification. • Area specific resistance (ASR = 0.84 Ω cm{sup 2} at 800 °C) optimized for Ca{sub 2.99}Cu{sub 0.01}Co{sub 4}O{sub 9−δ}.

Alkali passivation mechanism of sol-gel derived TiO2-SiO2 films coated on soda-lime-silica glass substrates

Energy Technology Data Exchange (ETDEWEB)

Matsuda, A; Matsuno, Y; Katayama, S; Tsuno, T [Nippon Steel Glass Co. Ltd., Tokyo (Japan); Toge, N; Minami, T [University of Osaka Prefecture, Osaka (Japan). College of Engineering

1992-09-01

TiO2-SiO2 films prepared by the sol-gel method serves as an effective alkali passivation layer on a soda-lime-silica glass substrate and the film is superior to a sol-gel derived pure SiO2 film from the view point of weathering resistance improvement. To clarify the reason, alkali passivation mechanism of sol-gel derived TiO2-SiO2 glass films with different TiO2 contents coated on a soda-lime-silica glass substrate was studied by SIMS (secondary ion mass spectroscopy) and XPS (X-ray photoelectron spectroscopy) analyses, and compared with the results of a sol-gel derived pure SiO2 film. As a result, the following conclusions were obtained: An increase in TiO2 content in the TiO2 SiO2 film increases the sodium concentration in the film, which was induced by sodium migration from the glass substrate during the heat-treatment. Because of the presence of sodium the TiO2 -SiO2 films serve not as a barrier but as an effective getter of alkali ions and thereby effectively improve the weathering resistance Of the glass substrate. 10 refs., 6 figs.

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

International Nuclear Information System (INIS)

1988-08-01

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.)

Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

Science.gov (United States)

Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

2005-07-01

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).

Annealing temperature effect on the properties of mercury-doped TiO2 films prepared by sol-gel dip-coating technique

International Nuclear Information System (INIS)

Mechiakh, R.; Ben Sedrine, N.; Karyaoui, M.; Chtourou, R.

2011-01-01

This work presents the annealing temperature effect on the properties of mercury (Hg)-doped titanium dioxide (TiO 2 ). Thin films and polycrystalline powders have been prepared by sol-gel process. The structure, surface morphology and optical properties, as a function of the annealing temperature, have been studied by atomic force microscopy (AFM), Raman, reflectance and ellipsometric spectroscopies. In order to determine the transformation points, we have analyzed the xerogel-obtained powder by differential scanning calorimetry (DSC). Raman spectroscopy shows the crystalline anatase and rutile phases for the films annealed at 400 deg. C and 1000 deg. C respectively. The AFM surface morphology results indicate that the particle size increases from 14 to 57 nm by increasing the annealing temperature. The complex index and the optical band gap (E g ) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreases by increasing the annealing temperature.

Complex anticorrosion coating for ZK30 magnesium alloy

International Nuclear Information System (INIS)

Lamaka, S.V.; Knoernschild, G.; Snihirova, D.V.; Taryba, M.G.; Zheludkevich, M.L.; Ferreira, M.G.S.

2009-01-01

This work aims at developing a new complex anticorrosion protection system for ZK30 magnesium alloy. This protective coating is based on an anodic oxide layer loaded with corrosion inhibitors in its pores, which is then sealed with a sol-gel hybrid polymer. The porous oxide layer is produced by spark anodizing. The sol-gel film shows good adhesion to the oxide layer as it penetrates through the pores of the anodized layer forming an additional transient oxide-sol-gel interlayer. The thickness of this complex protective coating is about 3.7-7.0 μm. A blank oxide-sol-gel coating system or one doped with Ce 3+ ions proved to be effective corrosion protection for the magnesium alloy preventing corrosion attack after exposure for a relatively long duration in an aggressive NaCl solution. The structure and the thickness of the anodized layer and the sol-gel film were characterized by scanning electron microscopy (SEM). The corrosion behaviour of the ZK30 substrates pre-treated with the complex coating was tested by electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET), and scanning ion-selective electrode techniques (SIET).

Fabrication of silica ceramic membrane via sol-gel dip-coating method at different nitric acid amount

Science.gov (United States)

Kahlib, N. A. Z.; Daud, F. D. M.; Mel, M.; Hairin, A. L. N.; Azhar, A. Z. A.; Hassan, N. A.

2018-01-01

Fabrication of silica ceramics via the sol-gel method has offered more advantages over other methods in the fabrication of ceramic membrane, such as simple operation, high purity homogeneous, well defined-structure and complex shapes of end products. This work presents the fabrication of silica ceramic membrane via sol-gel dip-coating methods by varying nitric acid amount. The nitric acid plays an important role as catalyst in fabrication reaction which involved hydrolysis and condensation process. The tubular ceramic support, used as the substrate, was dipped into the sol of Tetrethylorthosilicate (TEOS), distilled water and ethanol with the addition of nitric acid. The fabricated silica membrane was then characterized by (Field Emission Scanning Electron Microscope) FESEM and (Fourier transform infrared spectroscopy) FTIR to determine structural and chemical properties at different amount of acids. From the XRD analysis, the fabricated silica ceramic membrane showed the existence of silicate hydrate in the final product. FESEM images indicated that the silica ceramic membrane has been deposited on the tubular ceramic support as a substrate and penetrate into the pore walls. The intensity peak of FTIR decreased with increasing of amount of acids. Hence, the 8 ml of acid has demonstrated the appropriate amount of catalyst in fabricating good physical and chemical characteristic of silica ceramic membrane.

Nonhydrolytic sol-gel approach to facile creation of surface-bonded zirconia organic-inorganic hybrid coatings for sample preparation. Ι. Capillary microextraction of catecholamine neurotransmitters.

Science.gov (United States)

Alhendal, Abdullah; Mengis, Stephanie; Matthews, Jacob; Malik, Abdul

2016-10-14

Nonhydrolytic sol-gel (NHSG) route was used for the creation of novel zirconia-polypropylene oxide (ZrO 2 -PPO) sol-gel hybrid sorbents in the form of surface coatings for the extraction and preconcentration of catecholamine neurotransmitters and molecules structurally related to their deaminated metabolites. In comparison to other sorbents made of inorganic transition metal oxides, the presented hybrid organic-inorganic sorbents facilitated reversible sorption properties that allowed for efficient desorption of the extracted analytes by LC-MS compatible mobile phases. The presented sol-gel hybrid sorbents effectively overcame the major drawbacks of traditional silica- or polymer-based sorbents by providing superior pH stability (pH range: 0-14), and a variety of intermolecular interactions. Nonaqueous sol-gel treatment of PPO with ZrCl 4 was employed for the derivatization of the terminal hydroxyl groups on PPO, providing zirconium trichloride-containing end groups characterized by enhanced sol-gel reactivity. NHSG ZrO 2 -PPO sorbent provided excellent microextraction performance for catecholamines, low detection limits (5.6-9.6pM), high run-to-run reproducibility (RSD 0.6-5.1%), high desorption efficiency (95.0-99.5%) and high enrichment factors (∼1480-2650) for dopamine and epinephrine, respectively, extracted from synthetic urine samples. The presented sol-gel sorbents provided effective alternative to conventional extraction media providing unique physicochemical characteristics and excellent extraction capability. Copyright © 2016 Elsevier B.V. All rights reserved.

Persistent superhydrophilicity of sol-gel derived nanoporous silica thin films

International Nuclear Information System (INIS)

Ganjoo, S; Azimirad, R; Akhavan, O; Moshfegh, A Z

2009-01-01

In this investigation, sol-gel synthesized nanoporous silica thin films, annealed at different temperatures, with long time superhydrophilic property have been studied. Two kinds of sol-gel silica thin films were fabricated by dip-coating of glass substrates in two different solutions; with low and high water. The transparent coated films were dried at 100 deg. C and then annealed in a temperature range of 200-500 deg. C. The average water contact angle of the silica films prepared with low water content and annealed at 300 deg. C measured about 5 deg. for a long time (6 months) without any UV irradiation. Instead, adding water into the sol resulted in silica films with an average water contact angle greater than 60 deg. Atomic force microscopic analysis revealed that the silica films prepared with low water had a rough surface (∼30 nm), while the films prepared with high water had a smoother surface (∼2 nm). Using x-ray photoelectron spectroscopy, we have shown that with a decrease in the surface water on the film, its hydrophilicity increases logarithmically.

Preparation and characterization of conductive and transparent ruthenium dioxide sol-gel films.

Science.gov (United States)

Allhusen, John S; Conboy, John C

2013-11-27

RuO2 conductive thin films were synthesized using the sol-gel method and deposited onto transparent insulating substrates. The optical transmission, film thickness, surface morphology and composition, resistivity, and spectroelectrochemical performance have been characterized. The optical transmission values of these films ranged from 70 to 89% in the visible region and from 56 to 88% in the infrared region. Resistivity values of the RuO2 sol-gel films varied from 1.02 × 10(-3) to 1.13 Ω cm and are highly dependent on the initial solution concentration of RuO2 in the sol-gel. The RuO2 sol-gel films were used as electrodes for the electrochemical oxidation and reduction of ferrocenemethanol. The electrochemical behavior of our novel RuO2 sol-gel films was compared to that of a standard platinum disk electrode and showed no appreciable differences in the half-wave potential (E1/2). The mechanical and chemical stability of the coatings was tested by physical abrasion and exposure to highly acidic, oxidizing Piranha solution. Repeated exposure to these extreme conditions did not result in any appreciable decline in electrochemical performance. Finally, the use of the novel RuO2 sol-gel conductive and transparent films was demonstrated in a spectroelectrochemistry experiment in which the oxidation and reduction of ferrocenemethanol was monitored via UV-vis spectroscopy as the applied potential was cycled.

Carbamazepine degradation using a N-doped TiO{sub 2} coated photocatalytic membrane reactor: Influence of physical parameters

Energy Technology Data Exchange (ETDEWEB)

Horovitz, Inna [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Avisar, Dror [The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Baker, Mark A.; Grilli, Rossana [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Lozzi, Luca; Di Camillo, Daniela [Department of Physical and Chemical Sciences, University of L' Aquila, Via Vetoio, I-67100 L' Aquila (Italy); Mamane, Hadas, E-mail: hadasmg@post.tau.ac.il [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2016-06-05

Highlights: • UV–vis N-doped TiO{sub 2} was deposited by sol-gel onto Al{sub 2}O{sub 3} microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al{sub 2}O{sub 3} membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO{sub 2} vs. non-doped TiO{sub 2} membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al{sub 2}O{sub 3} photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO{sub 2} photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO{sub 2} films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO{sub 2}-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO{sub 2}-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

Nano crystals of Ni doped Zn O semiconductor by Sol-Gel combustion method

Energy Technology Data Exchange (ETDEWEB)

Carrero, A.; Sagredo, V. [Universidad de Los Andes, Departamento de Fisica, Laboratorio de Magnetismo, 5101 Merida (Venezuela, Bolivarian Republic of); Larionova, J., E-mail: aneelyc@gmail.com [Universite Montpellier II, 2 Place Eugene Bataillon, 34090 Montpellier (France)

2016-11-01

Nanoparticles of the system Zn{sub 0.95}O were prepared by sol-gel self - combustion method and a study of their structural, optical and magnetic properties were conducted. X-ray diffraction study shows a hexagonal wurtzite structure for the nano compound. The formation of the wurtzite structure in Ni doped Zn O was further confirmed by Fourier transform infra-red spectrometry. Transmission electron microscopy revealed an average size of 31 nm for the particles. Optical absorption spectra shows that the band energy of Zn{sub 0.95}Ni{sub 0.}9{sub 5}O powders is about 2.54 eV at room temperature. A study of the magnetic properties of the nano powders of Zn O: Ni, reveals paramagnetic behavior, with interaction ferromagnetic between particles. (Author)

Synthesis of cadmium tungstate films via sol-gel processing

Energy Technology Data Exchange (ETDEWEB)

Lennstrom, Kirk; Limmer, Steven J.; Cao Guozhong

2003-06-23

Cadmium tungstate is a scintillator material with excellent intrinsic photoluminescent properties. It is highly resistant to gamma radiation, has an almost non-existent afterglow and is highly efficient. Cadmium tungstate is also non-hydroscopic, unlike the more prevalent thallium-doped alkali halide scintillators. In order to create thin films of cadmium tungstate with precise stoichiometric control, a sol-gel processing technique has been applied to produce this material for the first time. In addition to lower processing temperatures, sol-gel-derived cadmium tungstate is cheaper and easier than other technologies, particularly for thin films. Furthermore, it has the potential to produce nanostructured materials with good optical quality. X-Ray diffraction results of sol-gel-derived materials fired at various temperatures imply crystallization of cadmium tungstate without the intermediate formation of either tungsten oxide or cadmium oxide. Scanning electron microscopy analysis shows the formation of nano-sized particles prior to heat treatment, which form meso-sized particles after the heat treatment. Photoluminesce analysis indicates emission of derived films at 480 nm, which agrees with other published data. Finally, the efficiency of derived films was approximately 6%{+-}1.8%.

Spectral features and antibacterial properties of Cu-doped ZnO nanoparticles prepared by sol-gel method

International Nuclear Information System (INIS)

Samavati, Alireza; Nur, Hadi; Othaman, Z; Ismail, A F; Mustafa, M K

2016-01-01

Zn 1−x Cu x O (x = 0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5% ( x = 0.05). However, the peak corresponding to CuO for x = 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli (Gram negative bacteria) cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping. (paper)

Process of forming a sol-gel/metal hydride composite

Science.gov (United States)

Congdon, James W [Aiken, SC

2009-03-17

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

Surface characterisation and photocatalytic performance of N-doped TiO{sub 2} thin films deposited onto 200 nm pore size alumina membranes by sol–gel methods

Energy Technology Data Exchange (ETDEWEB)

Grilli, R., E-mail: r.grilli@surrey.ac.uk [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Di Camillo, D.; Lozzi, L. [Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy); Horovitz, I.; Mamane, H.; Avisar, D. [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Baker, M.A. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom)

2015-06-01

Membrane filtration is employed for water treatment and wastewater reclamation purposes, but membranes alone are unable to remove pollutant molecules and certain pathogens. Photocatalytically active N-doped TiO{sub 2} coatings have been deposited by sol–gel onto 200 nm pore size alumina membranes for water treatment applications using two different methods, via pipette droplets or spiral bar applicator. The uncoated and coated membranes were characterised by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrometry (EDX). Both coatings showed the presence of N-doped anatase, with a surface coverage between 84 and 92%, and nitrogen concentration (predominantly interstitial) of 0.9 at.%. The spiral bar applicator deposited coatings exhibit a thicker mud-cracked surface layer with limited penetration of the porous membrane, whilst the pipette deposited coatings have mostly penetrated into the bulk of the membrane and a thinner layer is present at the surface. The photocatalytic activity (PCA), measured through the degradation of carbamazepine (CBZ), under irradiation of a solar simulator was 58.6% for the pipette coating and 63.3% for the spiral bar coating. These photocatalytically active N-doped sol–gel coated membranes offer strong potential in forming the fundamental basis of a sunlight based water treatment system. - Highlights: • Sol gel N-doped TiO{sub 2} thin films were deposited on 200 nm pore size Al{sub 2}O{sub 3} membranes. • Two sol–gel methods have been compared – pipette drop and spiral bar deposition. • The coatings showed a similar microstructure and composition but different morphology. • The PCA (degradation of carbamazepine) was ∼60% for both sol–gel coatings. • The coated membranes are promising for use in a membrane based water treatment system.

Sol-gel technology applied to alternative high-level waste forms development

International Nuclear Information System (INIS)

Angelini, P.; Stinton, D.P.; Vavruska, J.S.; Caputo, A.J.; Lackey, W.J.

1981-01-01

Sol-gel technology appears applicable to waste solidification. It is attractive for remote operation, and a variety of waste compositions and forms can be produced. Spheres and pellets of gel-derived Synroc waste forms were produced. Spheres of the Synroc-B type were coated with pyrolytic carbon and silicon carbide. Partitioning of actinides in Synroc-B was experimentally determined

Ceramic membrane by tape casting and sol-gel coating for microfiltration and ultrafiltration application

Science.gov (United States)

Das, Nandini; Maiti, H. S.

2009-11-01

Alumina membrane filters in the form of thin (0.3-0.8 mm) discs of 25-30 mm diameter suitable for microfiltration application have been fabricated by tape-casting technique. Further using this microfiltration membrane as substrate, boehmite sol coating was applied on it and ultrafiltration membrane with very small thickness was formed. The pore size of the microfiltration membrane could be varied in the range of 0.1-0.7 μm through optimisation of experimental parameter. In addition, each membrane shows a very narrow pore size distribution. The most important factor, which determines the pore size of the membrane, is the initial particle size and its distribution of the ceramic powder. The top thin ultrafiltration, boehmite layer was prepared by sol-gel method, with a thickness of 0.5 μm. Particle size of the sol was approximately 30-40 nm. The structure and formation of the layer was analysed through TEM. At 550 °C formation of the top layer was completed. The pore size of the ultrafiltration membrane measured from TEM micrograph was almost 10 nm. Results of microbial (Escherichia coli—smallest-sized water-borne bacteria) test confirm the possibility of separation through this membrane

Photostability and moisture uptake properties of wood veneers coated with a combination of thin sol-gel films and light stabilizers

Science.gov (United States)

Mandla A. Tshabalala; Ryan Libert; Christian M. Schaller

2011-01-01

In recent years, there has been increased interest in the use of inorganic UV blocking nanoparticles for photostabilization of wood surfaces. Photostability and moisture uptake properties of wood veneers coated with a combination of hybrid inorganic-organic thin sol-gel films and organic light stabilizers was investigated. The light stabilizers were applied by brushing...

Electrical, dielectric and photocatalytic properties of Fe-doped ZnO nanomaterials synthesized by sol gel method

Directory of Open Access Journals (Sweden)

Yacine Cherif

2016-09-01

Full Text Available Fe-doped ZnO nanoparticles were synthesized by sol gel technique. Fine-scale and single phase hexagonal wurtzite structure in all samples were confirmed by SEM and XRD, respectively. The band gap energy depends on the amount of Fe and was found to be in the range of 3.11–2.53 eV. The electric and dielectric properties were investigated using complex impedance spectroscopy. AC conductivity data were correlated with the barrier hopping (CBH model to evaluate the binding energy (Wm, the minimum hopping distance (Rmin and the density of states at Fermi level, N(EF. Fe doping in ZnO also improved the photocatalytic activity. Thus, the sample Zn0.95Fe0.05O showed high degradation potential towards methylene blue (MB, i.e. it degrades 90% of BM in 90 min under UV light.

Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene

Directory of Open Access Journals (Sweden)

Carolina Solis Maldonado

2014-03-01

Full Text Available The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al2O3 phase formed and to correlate the catalytic properties during trichloroethylene (TCE combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al2O3 surface. The X-ray photoelectron spectra (XPS, FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al2O3 lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene.

Science.gov (United States)

Maldonado, Carolina Solis; De la Rosa, Javier Rivera; Lucio-Ortiz, Carlos J; Hernández-Ramírez, Aracely; Barraza, Felipe F Castillón; Valente, Jaime S

2014-03-12

The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al₂O₃ phase formed and to correlate the catalytic properties during trichloroethylene (TCE) combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al₂O 3 surface. The X-ray photoelectron spectra (XPS), FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al₂O₃ lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

Investigations on electrical conductivity and dielectric properties of Na doped ZnO synthesized from sol gel method

Energy Technology Data Exchange (ETDEWEB)

Tabib, Asma; Sdiri, Nasr [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University Tunis El Manar, Tunis 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

2015-02-15

Highlights: • ZnO nanoparticles doped with Na were prepared from sol-gel method. • Electric conductivity and dielectric properties were investigated. • The ZnO conductivity is estimated to be of p-type for critical Na doping of 1.5% at. - Abstract: Na doped ZnO nanoparticles (NPs) were elaborated by sol gel technique. The X-ray diffraction patterns show that the peaks are indexed to the hexagonal structure without any trace of an extra phase. Electric and dielectric properties were investigated using complex impedance spectroscopy. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The contribution of grain boundary resistance to the total resistance of the system is remarkable. The AC conductivity increases with temperature following the Arrhenius law, with single apparent activation energy for conduction process. The frequency dependence of the electric conductivity follows a simple power law behavior, in according to relation σ{sub AC}(ω) = σ(0) + A ω{sup s}, where s is smaller than 1. The analysis of dc conductivity indicates that the conduction is ionic in nature. The study of its variation, at fixed temperature, with Na content shows sharp decrease which is explained by the formation of Na{sub Zn} acceptor. It was found that the dc conductivity reaches its minimum value for critical Na concentration of 1.5% at which the conductivity is estimated to be of p-type. Impedance and modulus study reveals the temperature dependent non-Debye type relaxation phenomenon. Dielectric studies revealed a promising dielectric properties (relatively high ε′ at low frequencies and low loss at high frequencies). In the low-frequency region, the values of M′ tends to zero suggesting negligible or absent electrode polarization phenomenon. The frequency dependent maxima in the imaginary modulus are found to obey to Arrhenius law.

Preparation of nitrogen-doped titania using sol-gel technique and its photocatalytic activity

International Nuclear Information System (INIS)

Qin Haoli; Gu Guobang; Liu Song

2008-01-01

Yellowish nitrogen-doped titania was produced through sol-gel method at room temperature, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using TG-DSC, XRD, BET, TEM, and UV-vis diffuse reflectance spectrophotometer. Methyl orange (MO) and 2-mercaptobenzothiazole (MBT) were used in this study as model chemicals and both the adsorption isotherm and photocatalytic activity of the nitrogen-doped titania catalysts were evaluated based on the MO and MBT photodegradation in aqueous solution under UV and visible light, respectively. The results showed that all titania catalysts were anatase. The crystallite size of nitrogen-doped ones increased with the increase of N/Ti proportion, both the adsorption capacity and adsorption equilibrium constants of the nitrogen-doped titania catalysts were improved by the doping of nitrogen. The doping of nitrogen could extend the absorption shoulder into the visible-light region, thus nitrogen-doped titania possessed visible-light activity illustrated by that higher capability of degradation of MO and MBT under the irradiation of visible light, whereas the pure ones showed little such kind of visible-light activity. The kinetics of the MO and MBT photodegradation using different nitrogen-doped titania were also studied, the experiments demonstrated that there was an optimum N/Ti proportion of 4 mol% to exhibit the highest visible-light activity. The UV activity of nitrogen-doped titania catalysts were worse than that of the pure one and Degussa P-25. In addition, nitrogen-doped titania had weakened appreciably activity in the visible-light region as the N/Ti proportion increased, while a reverse relationship exists for the UV light. It was concluded that the enhancement of MO and MBT photodegradation using the nitrogen-doped titania catalysts mainly involved in both the improvement of the organic substrate adsorption in catalysts suspension and the enhancement of the separation of electron

Sol-gel synthesis, characterization and optical properties of mercury-doped TiO{sub 2} thin films deposited on ITO glass substrates

Energy Technology Data Exchange (ETDEWEB)

Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Ben Sedrine, N.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia)

2011-08-15

The Hg-doped and undoped nano-crystalline TiO{sub 2} films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO{sub 2} were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO{sub 2}, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 {sup o}C. The average crystallite size of the undoped TiO{sub 2} films was about 8.17 nm and was increased with Hg-doping in the TiO{sub 2} films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO{sub 2} films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 {mu}m and the optical gap of the Hg-doped TiO{sub 2} thin films.

Sol-gel additive for systems with inorganic binders

International Nuclear Information System (INIS)

Akstinat, M.; Antenen, D.; Suter, W.

1996-01-01

A sol-gel additive for inorganic binder systems and sol-gel process for producing air-placed concrete and mortar by using such sol-gel additives are disclosed. Sol-gel additives for gel-derived inorganic binder systems (for example plaster, cement, lime, special slags, etc.) marked improve the consistency of such binder systems during processing or allow their consistency to be regulated. In addition, these sol-gel additives regulate setting times and substantially improve durability (chemical resistance, reduced permeability) and the mechanical properties of the set binder system. (author)

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

International Nuclear Information System (INIS)

1990-01-01

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.)

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

International Nuclear Information System (INIS)

1989-09-01

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.)

Annealing temperature effect on the properties of mercury-doped TiO{sub 2} films prepared by sol-gel dip-coating technique

Energy Technology Data Exchange (ETDEWEB)

Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar Batna, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Ben Sedrine, N. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Karyaoui, M. [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar Batna, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia)

2011-04-15

This work presents the annealing temperature effect on the properties of mercury (Hg)-doped titanium dioxide (TiO{sub 2}). Thin films and polycrystalline powders have been prepared by sol-gel process. The structure, surface morphology and optical properties, as a function of the annealing temperature, have been studied by atomic force microscopy (AFM), Raman, reflectance and ellipsometric spectroscopies. In order to determine the transformation points, we have analyzed the xerogel-obtained powder by differential scanning calorimetry (DSC). Raman spectroscopy shows the crystalline anatase and rutile phases for the films annealed at 400 deg. C and 1000 deg. C respectively. The AFM surface morphology results indicate that the particle size increases from 14 to 57 nm by increasing the annealing temperature. The complex index and the optical band gap (E{sub g}) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreases by increasing the annealing temperature.

Effect of sol aging time on the anti-reflective properties of silica coatings templated with phosphoric acid

Directory of Open Access Journals (Sweden)

Wen Wen

Full Text Available Silica anti-reflective coatings have been prepared by a sol–gel dip-coating process using the sol containing phosphoric acid as a pore-forming template. The effect of the aging time of the sol on the anti-reflective properties has been investigated. The surface topography of the silica AR coatings has been characterized. With increasing sol aging time, more over-sized pores larger than 100 nm are formed in the silica coatings. These could act as scattering centers, scattering visible light and thereby lowering transmittance. The optimal aging time was identified as 1 day, and the corresponding silica coatings showed a maximum transmittance of 99.2%, representing an 8% increase compared to the bare glass substrate. Keywords: Thin films, Anti-reflective coatings, Aging, Dip-coating, Sol–gel preparation

Defect-induced luminescence in sol-gel silica samples doped with Co(II) at different concentrations

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Sandoval, S. [Centro de Investigacion y Estudios Avanzados, Queretaro, Apdo. Postal 1-798, Queretaro, Qro. 76001 (Mexico); Estevez, M. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico); Pacheco, S. [Instituto Mexicano del Petroleo, Av. 100 metros (Mexico); Vargas, S. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico); Rodriguez, R. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico)], E-mail: rogelior@servidor.unam.mx

2007-12-20

The defect-induced luminescence properties of silica samples prepared by the sol-gel method and doped with Co(II) are reported. Silica monoliths doped with different concentrations of Co(II) were laser irradiated (He-Ne 632.8 nm) producing fluorescence. However, this fluorescence is exponentially reduced with the irradiation time, to practically disappear. The rate the fluorescence decays can be well modeled with a double exponential function of the irradiation time, containing two different relaxation times; a baseline is also required to take into account some residual fluorescence. The characteristic times involved in this luminescence quenching process are in the range of seconds. This luminescence suppression can be associated to the local heating produced by the laser irradiation when focused in a small area (2 {mu}m in diameter) on the sample. This heating process reduces physical (grain boundaries, surface states) and chemical (oxygen vacancies produced by the dopant) defects in the sample.

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

Energy Technology Data Exchange (ETDEWEB)

Lian Xiaojuan; Yang Xin; Liu Shangjun; Xu Ying; Jiang Chunping; Chen Jinwei [College of Materials Science and Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu 610065 (China); Wang Ruilin, E-mail: rlwang26@yahoo.com.cn [College of Materials Science and Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu 610065 (China)

2012-01-15

Ti-doped {alpha}-Fe{sub 2}O{sub 3} thin films were successfully prepared on FTO substrates by the sol-gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed {alpha}-Fe{sub 2}O{sub 3} had a preferred (1 1 0) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed at high temperature. The IPCE could reach 32.6% at 400 nm without any additional potential vs. SCE. Titanium in the lattice can affect the photo electro chemical performance positively by increasing the conductivity of the thin film. So the excited electrons and holes could live longer, rather than recombining with each other rapidly as undoped hematite. And the efficient carrier density on the Ti-doped anode surface was higher than the undoped anode, which contribute to the well PEC performance.

Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

Science.gov (United States)

Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

2017-10-15

Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this

Laser sintering of doped strontium aluminate via modified sol-gel for use as a ceramic pigment

International Nuclear Information System (INIS)

Soares, F.M. dos S.; Valerio, M.E.G.

2017-01-01

Powder of Dy"3"+ co-doped SrAl_2O_4 :Eu"3"+ was produced via proteic sol-gel method, a modified sol-gel route which allows the formation of oxides at lower temperatures than other methods. CO_2 laser sintering was used as a method for heat treatment, effective in reducing trivalent europium ions in doped samples. Thermal analysis of the precursors, performed by TG and DTA, revealed that the crystallization of SrAl_2O_4 phase occurred at approximately 1060 °C. X-ray diffraction showed that the samples, before and after sintering, had monoclinic and hexagonal phases formation. DLS technique revealed the presence of nanosized and micrometric particles, and particle agglomerates, confirmed by SEM images. Micrographs of the fracture surface of a sintered pellet revealed a high degree of densification caused by heat treatment. Photoluminescence measurements showed that the samples after synthesis and before heat treatment with laser had reddish emission, composed of characteristic narrow emission lines from Eu"3"+ and more intense emission when the samples were excited at 265 nm. The laser treatment promoted the reduction of Eu"3"+ to Eu"2"+ and this effect was confirmed by the presence of a wide emission band in the green region of the spectrum with a maximum emission obtained after excitation at 350 nm. The luminescent decay time of the thermally treated sample was approximately 100 min. Via XRF measurements of acquired frit and DTA and TG of the frit, pigment and mixtures of both, it was noticed good compatibility in terms of thermal processes, that indicated that the pigment has a potential to be used in ceramic tiles. (author)

Brilliant molecular nanocrystals emerging from sol-gel thin films: towards a new generation of fluorescent biochips

International Nuclear Information System (INIS)

Dubuisson, E; Monnier, V; Sanz-Menez, N; Ibanez, A; Boury, B; Usson, Y; Pansu, R B

2009-01-01

To develop highly sensitive biosensors, we made directly available to biological aqueous solutions organic nanocrystals previously grown in the pores of sol-gel films. Through the controlled dissolution of the sol-gel surface, we obtained emerging nanocrystals that remained strongly anchored to the sol-gel coating for good mechanical stability of the final sensing device. We demonstrated that in the presence of a solution of DNA functionalized with a molecular probe, the nanocrystal fluorescence is strongly quenched by Foerster resonance energy transfer thus opening the way towards very sensitive fluorescent biosensors through biomolecules grafted onto fluorescent nanocrystals. Finally, this controlled dissolution, involving weak concentrated NaOH solution, is a generic process that can be used for the thinning of any kind of sol-gel layer.

Zirconium coatings doped with nanoparticles for the protection of stainless steel

International Nuclear Information System (INIS)

Pineda, F; Vargas, E; Martinez, C; Sancy, M; Rabagliati, F.M; Pavez, J; Paez, M.A

2008-01-01

The anticorrosive protection of metal alloys, like stainless steel, is usually carried out with chrome-based coatings, but the toxic wastes associated with the process minimizes its applicability. The above has motivated the search for alternative protection methodologies, among which are the inorganic polymers prepared by the sol-gel method, which are a viable protection alternative because of their outstanding chemical and physical properties in aggressive environments. Despite the method's benefits, the application of sol-gel coatings to metals exposed to highly corrosive materials is restricted due to the substantial porosity of the films. Recent studies report that this limiting factor can be diminished by adding inorganic nanoparticles to the polymeric matrices, significantly improving the anticorrosive properties of the coatings. Considering the above, this work evaluated the inclusion of iron oxide nanoparticles (III) in zirconium polymeric matrices for the protection of 316 and 316L stainless steel. Electrochemical techniques, such as polarization curves and electrochemical impedance spectroscopy and morphological analysis with atomic force microscopy were used for this purpose. The responses obtained showed improvements in the anticorrosive properties of the zirconium films when doped with nanoparticles, and the best protective response was obtained with the minimum amount of the nanomaterial, aided by a significant increase in the metallic material's passivity. A critical content of nanoparticles was also identified in the polymeric matrix, above which the coating suffers serious deterioration, caused by the apparent formation of percolation channels leading to the oversaturation of the polymeric matrix

Low Temperature Ferromagnetism and Optical Properties of Fe Doped ZnO Nanoparticles Synthesized by Sol-Gel Method

Directory of Open Access Journals (Sweden)

B. Sathya

2017-06-01

Full Text Available In this present investigation, pure and Fe doped Zinc oxide nanoparticles were successfully synthesized by sol gel method.The structural and optical properties were examined by using X-ray diffraction (XRD, Scanning electron microscope (SEM, Transmission electron microscope (TEM, Ultraviolet spectroscopy and Photoluminescence (PL techniques.The structural characterization of XRD analysis confirmed the phase purity of the samples and crystallite size can be decreased with increasing doping concentrations.SEM image show that nanoparticles in spherical shape. The optical band gap calculated through UV-visible spectroscopy is found to be increasing from 3.48 to 3.57eV. TEM analysis depicted the crystallinity of nanoparticles prepared and chemical composition conformed the EDAX analysis. The PL spectra reveal that, Fe doped ZnO exhibit a decrease in intensity of the band edge emission peak while the intensity of the deep level emission peak increases.The enhancement of low temperature ferromagnetism in ZnO: Fe was achieved.

Fabrication of ceramic oxide-coated SWNT composites by sol-gel process with a polymer glue

Science.gov (United States)

Zhang, Cheng; Gao, Lei; Chen, Yongming

2011-09-01

The functional copolymer bearing alkoxysilyl and pyrene groups, poly[3-(triethoxysilyl)propyl methacrylate]- co-[(1-pyrene-methyl) methacrylate] (TEPM13- co-PyMMA3), was synthesized via atom transfer radical polymerization. Attributing the π-π interaction of pyrene units with the walls of single-walled carbon nanotubes (SWNTs), this polymer could disperse and exfoliate SWNTs in different solvents through physical interaction as demonstrated by TEM, UV/Vis absorption, and FT-IR analysis. The alkoxysilyl groups functionalized SWNTs were reacted with different inorganic precursors via sol-gel reaction, and, as a results, silica, titania, and alumina were coated onto the surface of SWNTs, respectively via copolymers as a molecular glue. The nanocomposites of ceramic oxides/SWNTs were characterized by SEM analysis. Dependent upon the feed, the thickness of inorganic coating can be tuned easily. This study supplies a facile and general way to coat SWNTs with ceramic oxides without deteriorating the properties of pristine SWNTs.

Sol-Gel Derived Active Material for Yb Thin-Disk Lasers.

Science.gov (United States)

Almeida, Rui M; Ribeiro, Tiago; Santos, Luís F

2017-09-02

A ytterbium doped active material for thin-disk laser was developed based on aluminosilicate and phosphosilicate glass matrices containing up to 30 mol% YbO 1.5 . Thick films and bulk samples were prepared by sol-gel processing. The structural nature of the base material was assessed by X-ray diffraction and Raman spectroscopy and the film morphology was evidenced by scanning electron microscopy. The photoluminescence (PL) properties of different compositions, including emission spectra and lifetimes, were also studied. Er 3+ was used as an internal reference to compare the intensities of the Yb 3+ PL peaks at ~ 1020 nm. The Yb 3+ PL lifetimes were found to vary between 1.0 and 0.5 ms when the Yb concentration increased from 3 to 30 mol%. Based on a figure of merit, the best active material selected was the aluminosilicate glass composition 71 SiO₂-14 AlO 1.5 -15 YbO 1.5 (in mol%). An active disk, ~ 36 μm thick, consisting of a Bragg mirror, an aluminosilicate layer doped with 15 mol% Yb and an anti-reflective coating, was fabricated.

Sol-gel derived sorbents

Science.gov (United States)

Sigman, Michael E.; Dindal, Amy B.

2003-11-11

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

Scratch resistance of SiO{sub 2} and SiO{sub 2} - ZrO{sub 2} sol-gel coatings on glass-ceramic obtained by sintering; Resistencia al desgaste de recubrimientos sol-gel de SiO{sub 2} y SiO{sub 2} - ZrO{sub 2} sobre materiales vitroceramicos obtenidos por sinterizacion

Energy Technology Data Exchange (ETDEWEB)

Soares, V. O.; Soares, P.; Peitl, O.; Zanotto, E. D.; Duran, A.; Castro, Y.

2013-10-01

The sol-gel process is widely used to obtain coatings on glass-ceramic substrates in order to improve the scratch and abrasion resistance, also providing a bright and homogeneous appearance of a glaze avoiding expensive final polishing treatments. This paper describes the preparation of silica and silica / zirconia coatings by sol-gel method on Li{sub 2}O-Al{sub 2}O3-SiO{sub 2} (LAS) glassceramic substrates produced by sintering. The coatings were deposited by dip-coating on LAS substrates and characterized by optical microscopy and spectral ellipsometry. On the other hand, hardness and elastic modulus, coefficient of friction and abrasion and scratch resistance of the coatings were determined and compared with the substrate properties. Coatings deposited on LAS glass-ceramic confere the substrate a bright and homogeneous aspect, similar to a glaze, improving the appearance and avoiding the final polishing. However these coatings do not increase the scratch resistance of the substrate only equaling the properties of the glass-ceramic. (Author)

Sol-Gel Manufactured Energetic Materials

Science.gov (United States)

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Critical ageing and chemistry of nanocrystalline hydroxyapatite sol-gel solutions

Energy Technology Data Exchange (ETDEWEB)

Chai, C.S.; Gross, K.A.; Kannangara, K.; Ben-Nissan, B. [University of Technology, Sydney, NSW (Australia). Department of Chemistry, Materials and Forensic Sciences; Hanley, L. [University of Illinois at Chicago, (United States). Department of Chemistry

1998-12-31

In previous work we have demonstrated that using alkoxide precursors, it is possible to produce crystalline hydroxyapatite coatings with potential uses in orthopaedic and dental applications. However, to produce monophasic hydroxyapatite coatings, sols must be aged for a minimum of 24 hours prior to deposition. {sup 31}P NMR has been used to analyse chemical changes occurring in the sol during the ageing process and have revealed that P-O-C bonds present in the precursor material are gradually replaced by P-O-Ca bonds with an accompanying change in oxidation state from P(III) to P(V). Thermal analysis was used to examine hydrolysed gels and showed that sols aged less than 24 hours contain unreacted calcium diethoxide which produces CaO upon heating. These findings have been confirmed by x-ray diffraction. Copyright (1998) Australasian Ceramic Society 16 refs., 4 figs.

Critical ageing and chemistry of nanocrystalline hydroxyapatite sol-gel solutions

International Nuclear Information System (INIS)

Chai, C.S.; Gross, K.A.; Kannangara, K.; Ben-Nissan, B.; Hanley, L.

1998-01-01

In previous work we have demonstrated that using alkoxide precursors, it is possible to produce crystalline hydroxyapatite coatings with potential uses in orthopaedic and dental applications. However, to produce monophasic hydroxyapatite coatings, sols must be aged for a minimum of 24 hours prior to deposition. 31 P NMR has been used to analyse chemical changes occurring in the sol during the ageing process and have revealed that P-O-C bonds present in the precursor material are gradually replaced by P-O-Ca bonds with an accompanying change in oxidation state from P(III) to P(V). Thermal analysis was used to examine hydrolysed gels and showed that sols aged less than 24 hours contain unreacted calcium diethoxide which produces CaO upon heating. These findings have been confirmed by x-ray diffraction. Copyright (1998) Australasian Ceramic Society

Study of silica sol-gel materials for sensor development

Science.gov (United States)

Lei, Qiong

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

Using sol-gel component as additive to foundry coatings to improve casting quality

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Poulsen, T.; Gravesen, B.

2012-01-01

The improvement of foundry coatings to enhance performance is important. This paper investigates the effect of using sol‐gel component as an additive to foundry coatings applied on chemically bonded sand cores. Three parameters at three levels each were investigated using Taguchi experimental...... was evaluated. The results show that the surface quality of castings obtained by adding the sol‐gel component to the coatings for cold box cores has no significant difference from castings produced with coatings without sol‐gel component. On the other hand, the addition of the sol‐gel component in coatings...

Sol-gel process for preparing YBa2Cu4O8 precursors from Y, Ba, and Cu acidic acetates/ammonia/ascorbic acid systems

International Nuclear Information System (INIS)

Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.

1995-08-01

Sols were prepared by addition of ammonia to acidic acetate solutions of Y 3+ , Ba 2+ , and Cu 2+ . Ascorbic acid was added to a part of the sol. The resultant sols were gelled to a shard, a film, or microspheres by evaporation at 60 C or by extraction of water from drops of emulsion suspended in 2-ethylhexanol-1. Addition of ethanol to the sols facilitated the formation of gel films, fabricated by a dipping technique, on glass or silver substrates. At 100 C, gels that were formed in the presence of ascorbic acid were perfectly amorphous, in contrast to the crystalline acetate gels. Conversion of the amorphous ascorbate gels to final products was easier than for the acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings

Hybrid sol-gel optical materials

Science.gov (United States)

Zeigler, John M.

1992-01-01

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

Sol gel based fiber optic sensor for blook pH measurement

International Nuclear Information System (INIS)

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

1996-01-01

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

Sol-gel based mid-infrared evanescent wave sensors for detection of organophosphate pesticides in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Janotta, Markus; Karlowatz, Manfred; Vogt, Frank; Mizaikoff, Boris

2003-10-31

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 of selected organophosphates, i.e. parathion, fenitrothion and paraoxon, respectively, and their capability of suppressing interfering water background absorptions. Figures of merit are derived from calibration curves determined to assess sensitivity and reproducibility of the applied sensor system. It can be concluded that sol-gel coated infrared optical sensors enable reproducible detection of organophosphates down to the sub-ppm concentration range. Furthermore, measurement of spiked river water samples demonstrates feasibility as remote field sensor system. Once the required sensitivity is achieved, sol-gel based mid-infrared evanescent wave sensors have the potential of being an alternative to commonly applied biosensors for detection of organophosphates in environmental analysis, since they provide superior mechanical and chemical stability during application relevant periods of time.

Fabrication of highly conductive graphene/ITO transparent bi-film through CVD and organic additives-free sol-gel techniques.

Science.gov (United States)

Hemasiri, Bastian Waduge Naveen Harindu; Kim, Jae-Kwan; Lee, Ji-Myon

2017-12-19

Indium tin oxide (ITO) still remains as the main candidate for high-performance optoelectronic devices, but there is a vital requirement in the development of sol-gel based synthesizing techniques with regards to green environment and higher conductivity. Graphene/ITO transparent bi-film was synthesized by a two-step process: 10 wt. % tin-doped ITO thin films were produced by an environmentally friendly aqueous sol-gel spin coating technique with economical salts of In(NO 3 ) 3 .H 2 O and SnCl 4 , without using organic additives, on surface free energy enhanced (from 53.826 to 97.698 mJm -2 ) glass substrate by oxygen plasma treatment, which facilitated void-free continuous ITO film due to high surface wetting. The chemical vapor deposited monolayer graphene was transferred onto the synthesized ITO to enhance its electrical properties and it was capable of reducing sheet resistance over 12% while preserving the bi-film surface smoother. The ITO films contain the In 2 O 3 phase only and exhibit the polycrystalline nature of cubic structure with 14.35 ± 0.5 nm crystallite size. The graphene/ITO bi-film exhibits reproducible optical transparency with 88.66% transmittance at 550 nm wavelength, and electrical conductivity with sheet resistance of 117 Ω/sq which is much lower than that of individual sol-gel derived ITO film.

Preparation and characterization of multi-walled carbon nanotube/hydroxyapatite nanocomposite film dip coated on Ti-6Al-4V by sol-gel method for biomedical applications: an in vitro study.

Science.gov (United States)

Abrishamchian, Alireza; Hooshmand, Tabassom; Mohammadi, Mohammadreza; Najafi, Farhood

2013-05-01

In the present research, the introduction of multi-walled carbon nanotubes (MWCNTs) into the hydroxyapatite (HA) matrix and dip coating of nanocomposite on titanium alloy (Ti-6Al-4V) plate was conducted in order to improve the performance of the HA-coated implant via the sol-gel method. The structural characterization and electron microscopy results confirmed well crystallized HA-MWCNT coating and homogenous dispersion of carbon nanotubes in the ceramic matrix at temperatures as low as 500 °C. The evaluation of the mechanical properties of HA and HA/MWCNT composite coatings with different weight percentages of MWCNTs showed that the addition of low concentrations of MWCNTs (0.5 and 1 wt.%) had improved effect on the mechanical properties of nanocomposite coatings. Moreover, this in vitro study ascertained the biocompatibility of the prepared sol-gel-derived HA/MWCNT composite coatings. Copyright © 2013 Elsevier B.V. All rights reserved.

Influence of Ni doping on phase transformation and optical properties of TiO2 films deposited on quartz substrates by sol-gel process

International Nuclear Information System (INIS)

Tian Jianjun; Deng Hongmei; Sun Lin; Kong Hui; Yang Pingxiong; Chu Junhao

2012-01-01

The Ni-doped TiO 2 films were synthesized on quartz substrates by the sol-gel method. Results from X-ray diffraction and Raman spectra indicate that Ni doping catalyzes the anatase-to-rutile transformation. When Ni content is up to 10 mol%, the transformation has been finished. The dielectric functions of Ni-doped TiO 2 films were extracted by fitting transmittance spectra according to the Adachi's dielectric function model. The optical band gap decreases from 3.64 eV to 3.51 eV with increasing Ni content. The results suggest that the acceleration of phase change and variation of optical properties may be related to defects due to Ni doping.

Optimization of sol-gel technique for coating of metallic substrates by hydroxyapatite using the Taguchi method

Science.gov (United States)

Pourbaghi-Masouleh, M.; Asgharzadeh, H.

2013-08-01

In this study, the Taguchi method of design of experiment (DOE) was used to optimize the hydroxyapatite (HA) coatings on various metallic substrates deposited by sol-gel dip-coating technique. The experimental design consisted of five factors including substrate material (A), surface preparation of substrate (B), dipping/withdrawal speed (C), number of layers (D), and calcination temperature (E) with three levels of each factor. An orthogonal array of L18 type with mixed levels of the control factors was utilized. The image processing of the micrographs of the coatings was conducted to determine the percentage of coated area ( PCA). Chemical and phase composition of HA coatings were studied by XRD, FT-IR, SEM, and EDS techniques. The analysis of variance (ANOVA) indicated that the PCA of HA coatings was significantly affected by the calcination temperature. The optimum conditions from signal-to-noise ( S/N) ratio analysis were A: pure Ti, B: polishing and etching for 24 h, C: 50 cm min-1, D: 1, and E: 300 °C. In the confirmation experiment using the optimum conditions, the HA coating with high PCA of 98.5 % was obtained.

Evaluation of hybrid sol-gel incorporated with nanoparticles as nano paint

International Nuclear Information System (INIS)

Jameel, Zainab N.; Haider, Adawiya J.; Taha, Samar Y.; Gangopadhyay, Shubhra; Bok, Sangho

2016-01-01

A coating with self-cleaning characteristics has been developed using a TiO_2/SiO_2 hybrid sol-gel, TiO_2 nanoparticles and organosilicate nanoparticles (OSNP). A patented technology of the hybrid sol-gel and OSNP was combined with TiO_2 nanoparticles to create the surface chemistry for self-cleaning. Two synthesis methods have been developed to prepare TiO_2 nanoparticles (NPs), resulting in the enhancement of local paint by the addition of anatase and rutile TiO_2 phases. The NPs size as determined by Dynamic Light Scattering (DLS) ranges within of (3-4) and (20-42) nm, which was also confirmed by Scanning Electron Microscopy (SEM). The nanoparticles showed surface charge (zeta-potential, ζ) of +35 and +25.62 mV for the methods, respectively, and ζ values of +41.31 and 34.02 mV for anatase and rutile phases, respectively. The NPs were mixed with the coating solution (i.e., hybrid sol-gel and OSNP) in different concentrations and thin films were prepared by spin coating. Self-cleaning tests were performed using Rhodamine B (RhB) as a pollution indicator. The effect of UV-irradiation on the films was also studied. Anatase and rutile incorporated as a mixture with different ratios in local paint and washability as well as a contrast ratio tests were performed. It was found that the addition of TiO_2 NPs in combination with irradiation show a great enhancement of RhB degradation (1%) wt. with a decrease in contact angle and improved washability.

Industrial applications of sol-gel technology

International Nuclear Information System (INIS)

Tuloch, S.M.; Tulloch, G.E.

1995-01-01

The purpose of this paper has been to provide a broad, rather than comprehensive view. We have presented a range of applications and only a selection of involved companies and researchers and have relied to a large extent on published information. Nevertheless, we are sure that our view of the importance of Sol-gel technology as an emerging technology, with enormous impact across a wide range of manufacturing, is demonstrated. Applications which are either in production or have been foreshadowed include four broad categories: coatings, fibres, powders and monoliths

Sol-gel-state of hydrated zirconium dioxide

International Nuclear Information System (INIS)

Karakchiev, L.G.; Lyakhov, N.Z.

1995-01-01

The change in viscosity and density of a system in the course of sol-gel-xerogel has been traced. The size and molecular mass of particles in sol have been determined. Initial sol is practically a monodisperse system. Gel is a spatial net of similar particles. Reversible character of sol-gel transition with a change in water content in the system suggests instability of the bond between the particles in the structure of the solid state body formed. 11 refs.; 4 figs

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

Science.gov (United States)

Shoup, Shara S.; Paranthamam, Mariappan; Beach, David B.; Kroeger, Donald M.; Goyal, Amit

2000-01-01

A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

Highly transparent ITO thin films on photosensitive glass: sol-gel synthesis, structure, morphology and optical properties

Energy Technology Data Exchange (ETDEWEB)

Koroesi, Laszlo; Papp, Szilvia; Dekany, Imre [University of Szeged, Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, Szeged (Hungary); Beke, Szabolcs [Italian Institute of Technology, Department of Nanophysics, Genova (Italy); Pecz, Bela; Horvath, Robert; Petrik, Peter; Agocs, Emil [Research Institute for Technical Physics and Materials Science, Budapest (Hungary)

2012-05-15

Conductive and highly transparent indium tin oxide (ITO) thin films were prepared on photosensitive glass substrates by the combination of sol-gel and spin-coating techniques. First, the substrates were coated with amorphous Sn-doped indium hydroxide, and these amorphous films were then calcined at 550 {sup circle} C to produce crystalline and electrically conductive ITO layers. The resulting thin films were characterized by means of scanning electron microscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The measurements revealed that the ITO films were composed of spherical crystallites around 20 nm in size with mainly cubic crystal structure. The ITO films acted as antireflection coatings increasing the transparency of the coated substrates compared to that of the bare supports. The developed ITO films with a thickness of {proportional_to}170-330 nm were highly transparent in the visible spectrum with sheet resistances of 4.0-13.7 k{omega}/sq. By coating photosensitive glass with ITO films, our results open up new perspectives in micro- and nano-technology, for example in fabricating conductive and highly transparent 3D microreactors. (orig.)

Structural Modification of Sol-Gel Synthesized V2O5 and TiO2 Thin Films with/without Erbium Doping

Directory of Open Access Journals (Sweden)

Fatma Pınar Gökdemir

2014-01-01

Full Text Available Comparative work of with/without erbium- (Er- doped vanadium pentoxide (V2O5 and titanium dioxide (TiO2 thin films were carried out via sol-gel technique by dissolving erbium (III nitrate pentahydrate (Er(NO33·5H2O in vanadium (V oxoisopropoxide (OV[OCH(CH32]3 and titanium (IV isopropoxide (Ti[OCH(CH32]4. Effect of Er doping was traced by Fourier transform IR (FTIR, thermogravimetric/differential thermal (TG/DTA, and photoluminescence measurements. UV-Vis transmission/absorption measurement indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond while appearance of typical absorption peaks in Er-doped TiO2 film. Granule size of the films increased (reduced upon Er substitution on host material compared to undoped V2O5 and TiO2 films, respectively.

Fast and efficient proteolysis by reusable pepsin-encapsulated magnetic sol-gel material for mass spectrometry-based proteomics applications.

Science.gov (United States)

Kayili, H Mehmet; Salih, Bekir

2016-08-01

Hydrophobic silicon-based material having magnetic properties was fairly synthesized by a classical sol-gel approach. Pepsin enzyme was encapsulated in the sol-gel material and the enzyme activity was evaluated in consequence of the digestion of some common proteins such as α- and β-casein, cytochrome c, myoglobin, and bovine serum albumin (BSA) both in a single protein batch and in the protein mixture. The optimum digestion time of the studied proteins using pepsin-encapsulated magnetic sol-gel material was found to be 20min. To produce the magnetic sol-gel material for convenient and easy proteomics applications, Fe3O4 was doped inside sol-gel material during the gelation step. It was observed that the activity of encapsulated pepsin was not affected by the amount of Fe3O4. Poly(ethylene glycol) was also inserted in sol-gel bulk to obtain suitable roughness and increase the hydrophilicity of the material surface to let protein molecules reach to the sol-gel material easily. The digestion of the protein mixture and non-fat bovine milk was performed with the pepsin-encapsulated magnetic sol-gel material and the digested solutions were analyzed using SDS-PAGE, MALDI-TOF-MS and LC-MS/MS for the protein identification. Reusability of the pepsin-encapsulated sol-gel material was examined and it was determined that they could be used at least 20 times. Finally, IgG digestions with a fast incubation time period were carried out using pepsin-encapsulated sol-gel material for generation of (Fab)2 product to evaluate the kinetic performance of the material. Copyright © 2016 Elsevier B.V. All rights reserved.

Sol-gel process for thermal reactor fuel fabrication

International Nuclear Information System (INIS)

Mukerjee, S.K.

2008-01-01

Full text: Sol-gel processes have revolutionized conventional ceramic technology by providing extremely fine and uniform powders for the fabrication of ceramics. The use of this technology for nuclear fuel fabrication has also been explored in many countries. Unlike the conventional sol-gel process, sol-gel process for nuclear fuels tries to eliminate the preparation of powders in view of the toxic nature of the powders particularly those of plutonium and 233 U. The elimination of powder handling thus makes this process more readily amenable for use in glove boxes or for remote handling. In this process, the first step is the preparation of microspheres of the fuel material from a solution which is then followed by vibro-compaction of these microspheres of different sizes to obtain the required smear density of fuel inside a pin. The maximum achievable packing density of 92 % makes it suitable for fast reactors only. With a view to extend the applicability of sol-gel process for thermal reactor fuel fabrication the concept of converting the gel microspheres derived from sol-gel process, to the pellets, has been under investigation for several years. The unique feature of this process is that it combines the advantages of sol-gel process for the preparation of fuel oxide gel microspheres of reproducible quality with proven irradiation behavior of the pellet fuel. One of the important pre-requisite for the success of this process is the preparation of soft oxide gel microspheres suitable for conversion to dense pellets free from berry structure. Studies on the internal gelation process, one of the many variants of sol-gel process, for obtaining soft oxide gel microspheres suitable for gel pelletisation is now under investigation at BARC. Some of the recent findings related to Sol-Gel Microsphere Pelletisation (SGMP) in urania-plutonia and thoria-urania systems will be presented

Effects of UV assistance on the properties of al-doped ZnO thin films deposited by sol-gel method

Science.gov (United States)

Tseng, Yung-Kuan; Pai, Feng-Ming; Chen, Yan-Cheng; Wu, Chao-Hsien

2013-11-01

We report here the preparation of aluminum doped zinc oxide transparent conductive thin films by a UV-assisted sol-gel method. It was found that UV irradiation creates ozone, which promotes the conductivity and transparency of the films. Boro-silicate glasses are used as substrates; an PGME is used as a solvent; after spin-coating, the films are dried and radiated with UV and then heated to 400°C for decarburization and 500°C for annealing under air. The surface morphologies of the prepared films are observed by FE-SEM and AFM. It was found that the films irradiated with UV-C are smoother and denser. An XRD analysis shows that the films have a typical wurtzite crystalline structure with a c-axis orientation normal to the surface. The electric resistance values measured with a four-point probe show that the films irradiated with UV have better conductivity (at approximately 3.4 × 10-3Ω-cm) than the films that did not undergo UV irradiation. An analysis by visible light spectrometry indicates that the AZO films irradiated with UV are more transparent than the films without UV-irradiation.

Ultra-small dye-doped silica nanoparticles via modified sol-gel technique

Science.gov (United States)

Riccò, R.; Nizzero, S.; Penna, E.; Meneghello, A.; Cretaio, E.; Enrichi, F.

2018-05-01

In modern biosensing and imaging, fluorescence-based methods constitute the most diffused approach to achieve optimal detection of analytes, both in solution and on the single-particle level. Despite the huge progresses made in recent decades in the development of plasmonic biosensors and label-free sensing techniques, fluorescent molecules remain the most commonly used contrast agents to date for commercial imaging and detection methods. However, they exhibit low stability, can be difficult to functionalise, and often result in a low signal-to-noise ratio. Thus, embedding fluorescent probes into robust and bio-compatible materials, such as silica nanoparticles, can substantially enhance the detection limit and dramatically increase the sensitivity. In this work, ultra-small fluorescent silica nanoparticles (NPs) for optical biosensing applications were doped with a fluorescent dye, using simple water-based sol-gel approaches based on the classical Stöber procedure. By systematically modulating reaction parameters, controllable size tuning of particle diameters as low as 10 nm was achieved. Particles morphology and optical response were evaluated showing a possible single-molecule behaviour, without employing microemulsion methods to achieve similar results. [Figure not available: see fulltext.

Composite Biomaterials Based on Sol-Gel Mesoporous Silicate Glasses: A Review

Science.gov (United States)

Baino, Francesco; Fiorilli, Sonia; Vitale-Brovarone, Chiara

2017-01-01

Bioactive glasses are able to bond to bone and stimulate the growth of new tissue while dissolving over time, which makes them ideal materials for regenerative medicine. The advent of mesoporous glasses, which are typically synthesized via sol-gel routes, allowed researchers to develop a broad and versatile class of novel biomaterials that combine superior bone regenerative potential (compared to traditional melt-derived glasses) with the ability of incorporating drugs and various biomolecules for targeted therapy in situ. Mesoporous glass particles can be directly embedded as a bioactive phase within a non-porous (e.g., microspheres), porous (3D scaffolds) or injectable matrix, or be processed to manufacture a surface coating on inorganic or organic (macro)porous substrates, thereby obtaining hierarchical structures with multiscale porosity. This review provides a picture of composite systems and coatings based on mesoporous glasses and highlights the challenges for the future, including the great potential of inorganic–organic hybrid sol-gel biomaterials. PMID:28952496

Spectral features and antibacterial properties of Cu-doped ZnO nanoparticles prepared by sol-gel method

Science.gov (United States)

Alireza, Samavati; A, F. Ismail; Hadi, Nur; Z, Othaman; M, K. Mustafa

2016-07-01

Zn1-x Cu x O (x = 0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5% (x = 0.05). However, the peak corresponding to CuO for x = 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30-52 nm. Doping Cu creates the Cu-O-Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli (Gram negative bacteria) cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping. Project supported by the Universiti Teknologi Malaysia (UTM) (Grant No. R. J1300000.7809.4F626). Dr. Samavati is thankful to RMC for postdoctoral grants.

Topography and surface energy dependent calcium phosphate formation on Sol-Gel derived TiO2 coatings.

Science.gov (United States)

Järn, Mikael; Areva, Sami; Pore, Viljami; Peltonen, Jouko; Linden, Mika

2006-09-12

Heterogeneous nucleation and growth of calcium phosphate (CaP) on sol-gel derived TiO(2) coatings was investigated in terms of surface topography and surface energy. The topography of the coatings was derived from AFM measurements, while the surface energy was determined with contact angle measurements. The degree of precipitation was examined with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The precipitation of CaP was found to be dependent on both topography and surface energy. A high roughness value when combining the RMS roughness parameter S(q) with the number of local maxima per unit area parameter S(ds) enhances CaP formation. The hydrophilicity of the coating was also found to be of importance for CaP formation. We suggest that the water contact angle, which is a direct measure of the hydrophilicity of the surface, may be used to evaluate the surface energy dependent precipitation kinetics rather than using the often applied Lewis base parameter.

Synthesis of polymeric fluorinated sol–gel precursor for fabrication of superhydrophobic coating

International Nuclear Information System (INIS)

Li, Qianqian; Yan, Yuheng; Yu, Miao; Song, Botao; Shi, Suqing; Gong, Yongkuan

2016-01-01

Graphical abstract: - Highlights: • A polymeric fluorinated sol–gel precursor PFT is designed to fabricate superhydrophobic coatings. • The superhydrophobicity could be governed by the concentration of PFT. • Bio-mimicking self-cleaning property similar to lotus leaves could also be achieved. - Abstract: A fluorinated polymeric sol–gel precursor (PFT) is synthesized by copolymerization of 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluorinated methyl)pentyl methacrylate (FMA) and 3-methacryloxypropyltrimethoxysilane (TSMA) to replace the expensive long chain fluorinated alkylsilanes. The fluorinated silica sol is prepared by introducing PFT as co-precursor of tetraethyl orthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as catalyst, which is then used to fabricate superhydrophobic coating on glass substrate through a simple dip-coating method. The effects of PFT concentrations on the chemical structure of the formed fluorinated silica, the surface chemical composition, surface morphology, wetting and self-cleaning properties of the resultant fluorinated silica coatings were studied by using X-ray powder diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrophotometer (XPS), scanning electron microscopy (SEM) and water contact angle measurements (WCA). The results show that the fluorinated silica sols are successfully obtained. The size and size distribution of the fluorinated silica particles are found greatly dependent on the concentration of PFT, which play a crucial role in the surface morphology of the corresponding fluorinated silica coatings. The suitable PFT concentration added in the sol–gel stage, i.e. for F-sol-1 and F-sol-2, is helpful to achieve both the low surface energy and multi-scaled microstructures, leading to the formation of the superhydrophobic coatings with bio-mimicking self-cleaning property similar to lotus leaves.

Flame retardant and hydrophobic properties of novel sol-gel derived phytic acid/silica hybrid organic-inorganic coatings for silk fabric

Science.gov (United States)

Cheng, Xian-Wei; Liang, Cheng-Xi; Guan, Jin-Ping; Yang, Xu-Hong; Tang, Ren-Cheng

2018-01-01

In this work, a novel phosphorus-rich hybrid organic-inorganic silica coating for improving the flame retardancy of silk fabric was prepared using naturally occurring phytic acid as phosphorus precursor and catalyst for the hydrolysis of tetraethoxysilane. In addition, three silane coupling agents, namely 3-aminopropyldimethoxymethylsilane, 3-chloropropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, were added in the hybrid sol as cross-linkers with the aim of developing hydrophobic coatings and improving the washing durability of the treated silk fabric. The condensation degree of the hybrid sol was characterized by solid-state 29Si nuclear magnetic resonance spectroscopy. The flammability and thermal degradation properties of the treated silk fabrics were determined in terms of limiting oxygen index, vertical burning, pyrolysis combustion flow calorimetry and thermogravimetric analyses. The surface morphology and hydrophobicity of the treated silk fabrics were evaluated by scanning electron microscopy, atomic force microscopy and water contact angle tests. The flammability tests revealed that the silicon sol could endow silk fabric with excellent flame retardancy when doped with phytic acid, and the treated silk fabrics self-extinguished immediately when the ignition source was removed. The silk fabrics treated with the modified hybrid sols exhibited hydrophobic surface and also better durability to washing.

Sol-gel syntheses of pentaborate β-LaB5O9 and the photoluminescence by doping with Eu3+, Tb3+, Ce3+, Sm3+, and Dy3+

Science.gov (United States)

Yang, Ruirui; Sun, Xiaorui; Jiang, Pengfei; Gao, Wenliang; Cong, Rihong; Yang, Tao

2018-02-01

Rare earth (RE) borates have been extensively studied as good photoluminescent materials, however, the target hosts were limited to "RE3BO6", REBO3, and REB3O6 in the RE2O3-B2O3 phase diagram until the recent discovery of rare earth pentaborate. For the first time, the sol-gel method was employed to synthesize β-LaB5O9 doped with Eu3+, Tb3+, Ce3+, Sm3+, Dy3+. In comparison to the previous synthetic methods, the sol-gel method possesses superiorities including easily-controllable doping concentration, high yield and emission efficiency. Solid solutions of phosphors were prepared and carefully analyzed by powder X-ray diffraction. Concentration quenching or saturation was observed in Eu3+, Tb3+ and Ce3+ doped phosphors at round 10 at%. Eu3+, Tb3+, Sm3+, and Dy3+ emit red, green, orange, and close-to-white light, respectively. The absolute emission efficiency of Ce3+ is high and in the UV range, suggesting the function of being sensitizer once combined with other activators.

Resistividade do filme depositado via sol-gel e estado de oxidação do dopante Ce na matriz SnO2 Resistivity of the film deposited via sol-gel and oxidation state of Ce doping in SnO2 matrix

Directory of Open Access Journals (Sweden)

L. V. A. Scalvi

2011-06-01

Full Text Available Incorporação de Ce3+ ou Ce4+ em filmes finos de SnO2 depositados via sol-gel-dip-coating aumenta drasticamente a resistividade elétrica. No primeiro caso, temos comportamento aceitador do dopante, levando a matriz à alta compensação de carga. Por outro lado, para Ce4+, verifica-se aumento na largura da região de depleção do contorno de grão, resultando em maior espalhamento de elétrons. Medidas de caracterização elétrica sob pressão ambiente levam à barreiras de potencial mais altas do que as medidas sob vácuo, devido a adsorção de oxigênio na superfície das partículas. A presença de Ce3+ aumenta a transmitância no infravermelho, o que significa menor quantidade de elétrons livres. Dados de XANES confirmam que o tratamento térmico a 550 ºC dos filmes, ainda que promova oxidação parcial para Ce4+, preserva uma quantidade significativa (em torno de 60% no estado Ce3+. Espectroscopia Raman mostra a evolução dos modos de vibração intra-grãos de SnO2 com o aumento da temperatura de tratamento térmico.Incorporation of Ce3+ or Ce4+ in sol-gel dip-coating SnO2 thin films increases drastically its electrical resistivity. In the first case, it is due the acceptor-like nature of the doping ion, leading the matrix to high charge compensation. On the other hand, for Ce+4 doped samples, it is verified a broadening of the grain boundary depletion layer. Measurements under room pressure leads to higher intergrain potential barriers when compared to measurements carried out under vacuum conditions, due to oxygen adsorption at particles surface. The presence of Ce3+ increases the infrared transmittance, which means a lower free electron concentration. XANES data confirms that the thermal annealing at 550 ºC of thin films, although promotes oxidation to Ce4+, still keeps a significantly amount (about 60% of ions in the oxidation state Ce3+. Raman spectroscopy data show the evolution of the SnO2 bulk vibration modes with

Effect of different sol concentrations on the properties of nanocrystalline ZnO thin films grown on FTO substrates by sol-gel spin-coating

International Nuclear Information System (INIS)

Kim, Ikhyun; Kim, Younggyu; Nam, Giwoong; Kim, Dongwan; Park, Minju; Kim, Haeun; Lee, Wookbin; Leem, Jaeyoung; Kim, Jongsu; Kim, Jin Soo

2014-01-01

Nanocrystalline ZnO thin films grown on fluorine-doped tinoxide (FTO) substrates were fabricated using the spin-coating method. The structural and the optical properties of the ZnO thin films prepared using different sol concentrations were investigated by using field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), photoluminescence (PL) measurements, and ultraviolet-visible (UV-vis) spectrometry. The surface morphology of the ZnO thin films, as observed in the SEM images, exhibited a mountain-chain structure. XRD results indicated that the thin films were preferentially orientated along the direction of the c-axis and that the grain size of the ZnO thin films increased with increasing sol concentration. The PL spectra showed a strong ultraviolet emission peak at 3.22 eV and a broad orange emission peak at 2.0 eV. The intensities of deep-level emission (DLE) gradually increased with increasing sol concentration from 0.4 to 1.0 M. The transmittance spectra of the ZnO thin films showed that the ZnO thin films were transparent (∼85%) in the visible region and exhibited sharp absorption edges at 375 nm. Thus, The Urbach energy of ZnO thin films decreased with increasing sol concentration.

Sol-gel preparation of uranium oxide spheres

International Nuclear Information System (INIS)

Dolezal, J.; Urbanek, V.

1978-01-01

Information is presented on problems of preparing nuclear fuel by the sol-gel method. Basic data on different process types are given. A more detailed description of the method of preparation of spherical particles of uranium oxide gel developed and used at the Nuclear Research Institute at Rez is given. Advantages and disadvantages of sol-gel materials are discussed in comparison with fuel materials prepared by classical precipitation methods. The feasibility of the sol-gel methods for preparing other materials is shortly mentioned and their application outlined. (author)

Luminescence behavior of the dibenzoyl methane europium(III) complexes in sol-gel derived host materials

International Nuclear Information System (INIS)

Wang Feng; Fan Xianping; Wang Minquan; Zhang Xianghua

2005-01-01

The luminescence behavior of the dibenzoyl methane europium(III) complexes (Eu(DBM) 3 ) in sol-gel derived host materials have been investigated. The steady-state excitation and emission spectra and the time-resolved spectra of the 1% EuCl 3 and 3% DBM co-doped gel indicated an efficient ligand-to-metal energy transfer. The Eu(DBM) 3 complexes in the gel showed longer 5 D 0 lifetimes in comparison with Eu(DBM) 3 .3H 2 O complexes. The luminescence intensity of the 1% EuCl 3 and 3% DBM co-doped gel decreased continuously with increasing temperature and time of heat treatment, which indicated the gradual decomposition of the Eu(DBM) 3 complexes in the gel during heat treatment

Evaluation of hybrid sol-gel incorporated with nanoparticles as nano paint

Energy Technology Data Exchange (ETDEWEB)

Jameel, Zainab N., E-mail: zeinb76-alrekbe@yahoo.com; Haider, Adawiya J., E-mail: adawiyahaider@yahoo.com [Nanotechnology and Advanced Materials Research Center, The University of Technology, Baghdad (Iraq); Taha, Samar Y., E-mail: samarjam2002@yahoo.com [College of Science for Women, University of Baghdad, Baghdad (Iraq); Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu; Bok, Sangho, E-mail: BokSa@missouri.edu [Department of Electrical and Computer, University of Missouri, Engineering, Building West, Columbia, Missouri 65211 (United States)

2016-07-25

A coating with self-cleaning characteristics has been developed using a TiO{sub 2}/SiO{sub 2} hybrid sol-gel, TiO{sub 2} nanoparticles and organosilicate nanoparticles (OSNP). A patented technology of the hybrid sol-gel and OSNP was combined with TiO{sub 2} nanoparticles to create the surface chemistry for self-cleaning. Two synthesis methods have been developed to prepare TiO{sub 2} nanoparticles (NPs), resulting in the enhancement of local paint by the addition of anatase and rutile TiO{sub 2} phases. The NPs size as determined by Dynamic Light Scattering (DLS) ranges within of (3-4) and (20-42) nm, which was also confirmed by Scanning Electron Microscopy (SEM). The nanoparticles showed surface charge (zeta-potential, ζ) of +35 and +25.62 mV for the methods, respectively, and ζ values of +41.31 and 34.02 mV for anatase and rutile phases, respectively. The NPs were mixed with the coating solution (i.e., hybrid sol-gel and OSNP) in different concentrations and thin films were prepared by spin coating. Self-cleaning tests were performed using Rhodamine B (RhB) as a pollution indicator. The effect of UV-irradiation on the films was also studied. Anatase and rutile incorporated as a mixture with different ratios in local paint and washability as well as a contrast ratio tests were performed. It was found that the addition of TiO{sub 2} NPs in combination with irradiation show a great enhancement of RhB degradation (1%) wt. with a decrease in contact angle and improved washability.

Structural, Morphological and Optical Characterization of Eu3+ and Nd3+ Co-Doped Tio2 Nano Particles by Sol Gel Method

Directory of Open Access Journals (Sweden)

P. Sanjay

2017-06-01

Full Text Available Semiconductor nano crystals have been widely studied for their fundamental properties. The Eu3+ and Nd3+ doped titanium dioxide nano powder was successfully synthesized by sol-gel method. The morphological and structural properties of as-prepared samples were characterized by X-ray diffraction (XRD, High Resolution Transmission Electron Microscope (HRTEM. The Powder X- ray diffraction is carried out in order to examine the phase formation and substitution of Eu3+ and Nd3+ doped in TiO2 matrix. The UV-Vis spectral analysis was carried out between 200 nm and 1200 nm. The band gap of the Eu3+ and Nd3+ doped Tio2 nanoparticles was calculated. The functional groups of the synthesized compound have been identified by FTIR spectral analysis. The strong PL intensity confirms a blue shift.

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

rhEGF-containing thermosensitive and mucoadhesive polymeric sol-gel for endoscopic treatment of gastric ulcer and bleeding.

Science.gov (United States)

Maeng, Jin Hee; So, Jung Won; Kim, Jungju; Kim, In Ae; Jung, Ji Hoon; Min, Kyunghyun; Lee, Don Haeng; Yang, Su-Geun

2014-03-01

Gastrointestinal endoscopy is a standard diagnostic tool for gastrointestinal ulcers and cancer. In this study, we have developed recombinant human epidermal growth factor-containing ulcer-coating polymeric sol-gel for endoscopic application. Chitosan and pluronic F127 were employed for their thermoresponsive and bioadhesive properties. At temperatures below 21, polymeric sol-gel remains liquid during endoscopic application and transforms to gel at body temperature after application on ulcers. In an in vitro cellular wounding assay, recombinant human epidermal growth factor sol-gel significantly enhanced the cell migration and decreased the wounding area (68%) compared to nontreated, recombinant human epidermal growth factor solution, and sol-gel without recombinant human epidermal growth factor (42, 49, and 32 % decreased at day 1). The in vivo ulcer-healing study was performed in an acetic acid-induced gastric ulcer rat model and proved that our recombinant human epidermal growth factor endoscopic sol-gel facilitated the ulcer-healing process more efficiently than the other treatments. Ulcer sizes in the recombinant human epidermal growth factor sol-gel group were decreased 2.9- and 2.1-fold compared with those in the nontreated group on days 1 and 3 after ulceration, respectively. The mucosal thickness in the recombinant human epidermal growth factor sol-gel group was significantly increased compared to that in the nontreated group (3.2- and 6.9-fold on days 1 and 3 after ulceration, respectively). In a gastric retention study, recombinant human epidermal growth factor sol-gel stayed on the gastric mucosa more than 2 h after application. The present study suggests that recombinant human epidermal growth factor sol-gel is a prospective candidate for treating gastric ulcers via endoscopic application.

Effect of sol-age on the surface and optical properties of sol-gel derived mesoporous zirconia thin films

Directory of Open Access Journals (Sweden)

Manish Kumar

2011-06-01

Full Text Available Mesoporous ZrO2 thin films have been deposited by a modified sol-gel dip coating technique using HCl as catalyst. Effects of sol-age on the surface and on the optical properties are studied. Transmission electron micrographs of the films reveal the pore dimensions in mesoporous regime. A strong correlation in surface topography with sol-age has been observed where increase in sol-age induces a systematic enhancement in the value of root mean square roughness of the films. Optical study shows that deposited films have high transmittance and an enhancement of 5.6 times in porosity in films prepared with sol-age of 10 days with respect to that of 1 day. Band gap estimation by Tauc's plots of films is observed to 5.74 eV, which shows invariance with the sol-age.

Synthesis of uranium and thorium dioxides by Complex Sol-Gel Processes (CSGP). Synthesis of uranium oxides by Complex Sol-Gel Processes (CSGP)

International Nuclear Information System (INIS)

Deptula, A.; Brykala, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Chmielewski, A.G.; Modolo, G.; Daniels, H.

2010-01-01

In the Institute of Nuclear Chemistry and Technology (INCT), a new method of synthesis of uranium and thorium dioxides by original variant of sol-gel method - Complex Sol-Gel Process (CSGP), has been elaborated. The main modification step is the formation of nitrate-ascorbate sols from components alkalized by aqueous ammonia. Those sols were gelled into: - irregularly agglomerates by evaporation of water; - medium sized microspheres (diameter <150) by IChTJ variant of sol-gel processes by water extraction from drops of emulsion sols in 2-ethylhexanol-1 by this solvent. Uranium dioxide was obtained by a reduction of gels with hydrogen at temperatures >700 deg. C, while thorium dioxide by a simple calcination in the air atmosphere. (authors)

Preparation of Flame Retardant Polyacrylonitrile Fabric Based on Sol-Gel and Layer-by-Layer Assembly.

Science.gov (United States)

Ren, Yuanlin; Huo, Tongguo; Qin, Yiwen; Liu, Xiaohui

2018-03-23

This paper aims to develop a novel method, i.e., sol-gel combined with layer-by-layer assembly technology, to impart flame retardancy on polyacrylonitrile (PAN) fabrics. Silica-sol was synthesized via the sol-gel process and acted as cationic solution, and phytic acid (PA) was used as the anionic medium. Flame-retardant-treated PAN fabric (FR-PAN) could achieve excellent flame retardancy with 10 bilayer (10BL) coating through layer-by-layer assembly. The structure of the fabrics was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The thermal stability and flame retardancy were evaluated by thermogravimetric (TG) analysis, cone calorimetry (CC) and limiting oxygen index (LOI). The LOI value of the coated fabric was up to 33.2 vol % and the char residue at 800 °C also increased to 57 wt %. Cone calorimetry tests revealed that, compared to the control fabric, the peak of heat release rate (PHRR) and total heat release (THR) of FR-PAN decreased by 66% and 73%, respectively. These results indicated that sol-gel combined with layer-by-layer assembly technique could impart PAN fabric with satisfactory flame-retardant properties, showing an efficient flame retardant strategy for PAN fabric.

Manufacture of Regularly Shaped Sol-Gel Pellets

Science.gov (United States)

Leventis, Nicholas; Johnston, James C.; Kinder, James D.

2006-01-01

An extrusion batch process for manufacturing regularly shaped sol-gel pellets has been devised as an improved alternative to a spray process that yields irregularly shaped pellets. The aspect ratio of regularly shaped pellets can be controlled more easily, while regularly shaped pellets pack more efficiently. In the extrusion process, a wet gel is pushed out of a mold and chopped repetitively into short, cylindrical pieces as it emerges from the mold. The pieces are collected and can be either (1) dried at ambient pressure to xerogel, (2) solvent exchanged and dried under ambient pressure to ambigels, or (3) supercritically dried to aerogel. Advantageously, the extruded pellets can be dropped directly in a cross-linking bath, where they develop a conformal polymer coating around the skeletal framework of the wet gel via reaction with the cross linker. These pellets can be dried to mechanically robust X-Aerogel.

Effect of nano-particulate sol-gel coatings on the oxidation resistance of high-strength steel alloys during the press-hardening process

Energy Technology Data Exchange (ETDEWEB)

Yekehtaz, M.; Benfer, S.; Fuerbeth, W. [DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany); Klesen, C.; Bleck, W. [Institut fuer Eisenhuettenkunde der RWTH Aachen, Intzestrasse 1, D-52072 Aachen (Germany)

2012-10-15

The need for lighter constructional materials in automotive industries has increased the use of high-strength steel alloys. To enhance passenger's safety press hardening may be applied to steel parts. However, as the steel parts are heated up to 950 C during this process they have to be protected by some kind of coating against the intense oxide formation usually taking place. As the coating systems used so far all have certain disadvantages in this work the ability of nano-particulate thin coatings obtained by the sol-gel process to improve the oxidation resistance of 22MnB5 steel is investigated. The coatings obtained from three sols containing lithium aluminum silicate and potassium aluminum silicate showed the best performance against oxidation. The structural properties of the coating materials were characterized using different methods like XRD and differential thermal analysis. Comparison of the oxidation rate constants proved the ability of the coatings to protect against oxidation at temperatures up to 800 C. Press-hardening experiments in combination with investigations on the thermal shock resistance of the coated samples also showed the ability of the coatings to stay intact during press hardening with only slight spalling of the coatings in the bending areas. The absence of any secondary intermetallic phases and layer residues during laser beam welding experiments on coated samples proves the suitability of the nano-particulate coatings for further industrial processing. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Fast Processing of Sol-Gel TCO

NARCIS (Netherlands)

Deelen, J. van; Rem, M.; Arfsten, N.; Buskens, P.P.

2016-01-01

TCOs are usually deposited using sputtering or chemical vapor deposition, which have a yield of typically 50-75%. The sol gel method does not need low pressure and can be done with a high precursor yield in the range of 90 – 100%. Sol gel enables also the TCO function as a planarization or

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

Directory of Open Access Journals (Sweden)

Ting Ke Tseng

2010-05-01

Full Text Available 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.

Influence of p H on optical properties of nano structure sol-gel-derived silica films

International Nuclear Information System (INIS)

Heshmatpuor, F.; Adelkhani, H.; Nahavandi, M.; Noorbakhsh Shourabadi, M.

2006-01-01

Sol-gel derived silica films were fabricated by dip-coating onto glass microscope substrates. Film properties such as transmission and surface morphology were monitored as function of dip speed and sol p H. Film transmission was increased with increasing of p H in visible range. The surface morphology of films were investigated with scanning electron microscopy.

Silica scintillating materials prepared by sol-gel methods

International Nuclear Information System (INIS)

Werst, D.W.; Sauer, M.C. Jr.; Cromack, K.R.; Lin, Y.; Tartakovsky, E.A.; Trifunac, A.D.

1993-01-01

Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons

Molten carbonate fuel cell cathode with mixed oxide coating

Science.gov (United States)

Hilmi, Abdelkader; Yuh, Chao-Yi

2013-05-07

A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

Evaluation of tetraethoxysilane (TEOS) sol–gel coatings, modified with green synthesized zinc oxide nanoparticles for combating microfouling

Energy Technology Data Exchange (ETDEWEB)

Krupa, A. Nithya Deva; Vimala, R., E-mail: vimala.r@vit.ac.in

2016-04-01

Green synthesis of zinc oxide nanoparticles (ZnO-NPs) is gaining importance as an eco-friendly alternative to conventional methods due to its enormous applications. The present work reports the synthesis of ZnO-NPs using the endosperm of Cocos nucifera (coconut water) and the bio-molecules responsible for nanoparticle formation have been identified. The synthesized nanoparticles were characterized using UV–Visible spectroscopy (UV–Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Zeta potential measurement. The results obtained reveal that the synthesized nanoparticles are moderately stable with the size ranging from 20 to 80 nm. The bactericidal effect of the nanoparticles was proved by well diffusion assay and determination of minimum inhibitory concentration (MIC) against marine biofilm forming bacteria. Further the green synthesized ZnO-NPs were doped with TEOS sol–gels (TESGs) in order to assess their antimicrofouling capability. Different volumes of liquid sol–gels were coated on to 96-well microtitre plate and cured under various conditions. The optimum curing conditions were found to be temperature 60 °C, time 72 h and volume 200 μl. Antiadhesion test of the undoped (SG) and ZnO-NP doped TEOS sol–gel (ZNSG) coatings were evaluated using marine biofilm forming bacteria. ZNSG coatings exhibited highest biofilm inhibition (89.2%) represented by lowest OD value against Pseudomonasotitidis strain NV1. - Highlights: • The study reports low cost, and simple procedure for the synthesis of ZnO-NPs using coconut water. • XRD result shows the high crystalline nature of the synthesized ZnO-NPs. • TEM and zeta potential distribution confirms the nanostructure, stability of the synthesized ZnO-NPs. • ZnO-NPs doped with TEOS sol¬-gels (TESGs) exhibited excellent antimicrofouling activity.

Bioorganically doped sol-gel materials containing amyloglucosidase activity

Directory of Open Access Journals (Sweden)

Vlad-Oros Beatrice

2006-01-01

Full Text Available Amyloglucosidase (AMG from Aspergillus niger was encapsulated in various matrices derived from tetraethoxysilane, methyltriethoxysilane, phenyltriethoxysilane and vinyltriacetoxysilane by different methods of immobilization. The immobilized enzyme was prepared by entrapment in two steps, in one-step and entrapment/deposition, respectively. The activities of the immobilized AMG were assayed and compared with that of the native enzyme. The effects of the organosilaneprecursors and their molar ratios, the immobilization method, the inorganic support (white ceramic, red ceramic, purolite, alumina, TiO2, celite, zeolite and enzyme loading upon the immobilized enzyme activity were tested. The efficiency of the sol-gel biocomposites can be improved through combination of the fundamental immobilization techniques and selection of the precursors.

Dielectric properties of Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} synthesized by sol-gel route

Energy Technology Data Exchange (ETDEWEB)

Jesurani, S. [Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625 601, Tamil Nadu (India); Center for Material Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603 203, Tamil Nadu (India); Kanagesan, S., E-mail: kanagu1980@gmail.com [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Ismail, I. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

2013-02-25

Highlights: Black-Right-Pointing-Pointer Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} samples have been synthesized using sol-gel process. Black-Right-Pointing-Pointer The particle size of the powder ranges from 47 to 85 nm. Black-Right-Pointing-Pointer Less sintering at 1040 Degree-Sign C results in high density and high dielectric constant. - Abstract: Zr substituted CaCu{sub 3}Ti{sub 4-x}Zr{sub x}O{sub 12} (CCTZO) with x = 0.00, 0.02, 0.10, 0.20 and 0.50 mol% were prepared by sol-gel route from the metal nitrate solutions, Titanium isoproxide, and zirconium oxy chloride. XRD analysis confirmed the formation of a single phase material in the samples calcinated at 800 Degree-Sign C for 3 h. The crystal structure did not change on doping with zirconium and it remained cubic in all the four studied compositions. The permittivity and dielectric loss of 0.1 mol% Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} were improved for K Almost-Equal-To 6020 and tan {delta} Almost-Equal-To 0.52 at 1 kHz after the sample had been sintered at 1040 Degree-Sign C for 4 h. AFM studies showed that the particle size of the CCTZO powder ranged from 47 to 85 nm. FE-SEM micrographs of the CaCu{sub 3}Ti{sub 4-x}Zr{sub x}O{sub 12} samples showed that the grain size was in the range of 250 nm to 5 {mu}m for these samples. EDX studies showed the presence of calcium, copper, titanium, oxygen and zirconium. Remarkably, the dielectric constant increased and dielectric loss had lower values compared to the undoped CCTO.

Fabrications and properties of doped porous polysiloxane sol-gel layers on optical fibers

Czech Academy of Sciences Publication Activity Database

Berková, Daniela; Sedlář, Miroslav; Matějec, Vlastimil; Kašík, Ivan; Chomát, Miroslav; Abdelghani, A.; Jaffrezic-Renault, N.; Lacroix, M.

1998-01-01

Roč. 13, 1/3 (1998), s. 569-573 ISSN 0928-0707. [Glasses, Ceramics, Hybrids and Nanocomposites from Gels - SOL-GEL'97 /9./. Sheffield, 31.08.1997-05.09.1997] R&D Projects: GA ČR GA102/95/0871; GA ČR GA102/96/0939 Keywords : nonelectric sensing devices * optical fibres Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.526, year: 1997

Preparation of Natural Rubber (NR) Based Nano-Sized Materials Using Sol-Gel Technique

International Nuclear Information System (INIS)

Dahlan Mohd; Mahathir Mohamed

2011-01-01

The objectives of this project are to prepare nano-sized natural rubber-based hybrid coating material by sol-gel technique; to explore the possibility of producing ENR-Si (epoxidized natural rubber-silica) cramer with toughening effects; and to use it in radiation curing of surface coating. Since early 1960s Malaysia has introduced various forms of value-added natural rubber such as Standard Malaysian Rubber (SMR), methylmethacrylate-grafted natural rubber (MG rubber), followed by liquid natural rubber and epoxidized natural rubber (ENR). Products such as liquid epoxidized natural rubber acrylate (LENRA) and thermoplastic natural rubber (TPNR) are still on-going research projects in Nuclear Malaysia. The former has strong possibility to be used as radiation-sensitive comparabilities in TPNR blends, besides its original purpose for example in radiation curing of surface coating. But earlier findings indicated that, to make it (as for surface coating) more effective, reinforcement system is needed to be introduced. Strong candidate is silica by sol-gel technique, since common reinforcement filler for example carbon black has drawbacks in this particular case. This technique was introduced in late 1960s to produce metal oxides such as silica and titanium oxides in solution. (author)

Fluorescence of Pentavalent Chromium in SiO2 Sol-Gel Glasses

Science.gov (United States)

Jia, Weiyi; Castro, Lymari; Wang, Yanyun; Liu, Huimin

1998-01-01

Chromium ions are very attractive to optical spectroscopy and laser physics. It is well known that the first laser in the history is a ruby laser activated with Cr(3+). It was found in early nineties that Cr(4+) was also an interesting lasing ion in the near infrared, and various Cr(4+) lasers have been developed. Very recently, it was reported that Cr(2+) doped in CdSe crystals showed lasing action in the infrared. The above achievement have stimulated an interest in searching for Cr(5+) and investigating its optical properties. Cr(5+) is isoelectronic with Ti(3+) and V(4+), having electron configuration 3d1. Ti(3+) is the active center of commercial cw and femtosecond sapphire lasers, tunable in the range 680-1100 nm. V(4+) doped in YAlO3 and Al2O3 showed broad band emission near 635 nm. Although EPR results of Cr(5+) were reported, the optical properties were less studied. Herren et al. reported an observation of luminescence from Cr doped in SiO2 sol-gel glass. The luminescence spectrum was assigned to pentavalent ions in their first paper, and later it was identified to be the emission from the charge transfer transition of Cr(6+). The first observation of photoluminescence from octahedrally coordinated Cr(5+) in BaCaMg aluminate glasses was reported very recently. In this work, we report luminescence results of Cr doped SiO2 sol-gel glasses. The fluorescence spectra are very different from Herrens' results, and we believe it originates from pentavalent Cr.

Visible emission from Er-doped SnO2 thin films deposited by sol-gel Emissão no visível de filmes finos, depositados via sol-gel, de SnO2 dopados com Er

Directory of Open Access Journals (Sweden)

L. P. Ravaro

2007-06-01

Full Text Available Emission from Er-doped SnO2 thin film deposited via sol-gel by the dip coating technique is obtained in the range 500-700 nm with peak at 530 nm (green. Electron-hole generation in the tin dioxide matrix is used to promote the rare-earth ion excitation. Evaluation of crystallite dimensions through X-ray diffraction results leads to nanoscopic size, what could play a relevant role in the emission spectra. The electron-hole mechanism is also responsible for the excitation of the transition in the 1540 nm range in powders obtained from the same precursor solution of films. The thin film matrix presents a very useful shape for technological application, since it allows integration in optical devices and the application of electric fields to operate electroluminescent devices.Foi obtida emissão de filmes finos de SnO2 dopados com Er no intervalo 500-700 nm, com pico em 530 nm (verde. Esses filmes foram depositados pela técnica de molhamento via sol-gel. A geração de pares elétron-buraco na matriz de SnO2 é usada para promover a excitação do íon terra-rara. A avaliação do tamanho dos cristalitos por meio de resultados de difração de raios X indica dimensões nanoscópicas, o que pode ser relevante para a interpretação do espectro de emissão. O mecanismo de excitação elétron-buraco é também responsável pela excitação da transição no intervalo que inclui 1540 nm em pós obtidos da mesma solução precursora dos filmes. Filmes finos constituem um formato muito útil para aplicações tecnológicas, desde que permite integração em dispositivos ópticos e a aplicação de campos elétricos para operar dispositivos eletroluminescentes.

Development and Characterization of 316 L Stainless Steel Coated by Melt-derived and Sol-gel derived 45S5 Bioglass for orthopedic applications

Directory of Open Access Journals (Sweden)

Seyed Morteza Naghib

2012-03-01

Full Text Available The 316L austenitic stainless steel (SS was coated by 45S5 bioactive glass produced by melting and sol-gel techniques to increase the bioactivity and to provide a high mechanical strength for orthopedic and dental applications. The morphologies of coated specimens were investigated by scanning electron microscopy (SEM. Then, the coated specimens were immersed in simulated body fluid (SBF at 37°C for 14 days, and their microstructures after withdrawal were also investigated by SEM. All the specimens were analyzed by FTIR and XRD in order to survey the formation of hydroxyapatite layer.

Sol-gel processing with inorganic metal salt precursors

Science.gov (United States)

Hu, Zhong-Cheng

2004-10-19

Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

Current and future possibilities of sol-gel process

International Nuclear Information System (INIS)

Sakka, Sumio

2004-01-01

The sol-gel method is characterized by the low temperature processing. Since this method starts from solutions, the product is essentially nanomaterials. So far, various kinds of microstructures, including dense, porous, hybrid, amorphous and crystalline microstructures have been realized. Accordingly, sol-gel materials cover a wide range of functions, such as optical, electronic, mechanical, chemical and bio-functions. Future perspectives of the sol-gel method are described in the article. (author)

Sol-gel-based biosensing applied to medicinal science.

Science.gov (United States)

Moreira, Felismina T C; Moreira-Tavares, Ana P; Sales, M Goreti F

2015-01-01

Biosensors have opened new horizons in biomedical analysis, by ensuring increased assay speed and flexibility, and allowing point-of-care applications, multi-target analyses, automation and reduced costs of testing. This has been a result of many studies merging nanotechnology with biochemistry over the years, thereby enabling the creation of more suitable environments to biological receptors and their substitution by synthetic analogue materials. Sol-gel chemistry, among other materials, is deeply involved in this process. Sol-gel processing allows the immobilization of organic molecules, biomacromolecules and cells maintaining their properties and activities, permitting their integration into different transduction devices, of electrochemical or optical nature, for single or multiple analyses. Sol-gel also allows to the production of synthetic materials mimicking the activity of natural receptors, while bringing advantages, mostly in terms of cost and stability. Moreover, the biocompatibility of sol-gel materials structures of biological nature allowed the use of these materials in emerging in vivo applications. In this chapter, biosensors for biomedical applications based on sol-gel derived composites are presented, compared and described, along with current emerging applications in vivo, concerning drug delivery or biomaterials. Sol-gel materials are shown as a promising tool for current, emerging and future medical applications.

AZO Thin Films by Sol-Gel Process for Integrated Optics

Directory of Open Access Journals (Sweden)

Azzedine Boudrioua

2013-07-01

Full Text Available Undoped and aluminum-doped zinc oxide (AZO thin films are prepared by the sol-gel process. Zinc acetate dihydrate, ethanol, and monoethanolamine are used as precursor, solvent, and stabilizer, respectively. In the case of AZO, aluminum nitrate nonahydrate is added to the precursor solution with an atomic percentage equal to 1 and 2 at.% Al. The multi thin layers are deposited by spin-coating onto glass substrates, and are transformed into ZnO upon annealing at 550 °C. Films display a strong preferential orientation, with high values for the Texture Coefficients (TC of the (002 direction (TC(002 ≈ 3. The structural, morphological, and optical properties of the thin films as a function of aluminum content have been investigated using X-Ray Diffraction (XRD, Atomic Force Microscopy (AFM, and Scanning Electronic Microscopy (SEM. Waveguiding properties of the thin films have been also studied using m-lines spectroscopy. The results indicate that the films are monomodes at 632.8 nm with optical propagation optical losses estimated around 1.6 decibel per cm (dB/cm.

Effect of sol concentration on the properties of ZnO thin films prepared by sol-gel technique

International Nuclear Information System (INIS)

Dutta, M.; Mridha, S.; Basak, D.

2008-01-01

ZnO thin films are deposited on the glass substrates by sol-gel drain coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. The results show that with increase in sol concentration, the value of full width at half maximum (FWHM) of (0 0 2) peak decreases while the strain first increases and then decreases. The sol with higher concentration results in the increase in the grain size. The studies on the optical properties show that the band gap value increases from 3.27 to 3.3 eV when the sol concentration changes from 0.03 to 0.1 M. The photoconductivity studies reveal that the film for 0.05 M sol shows the maximum photoresponse for ultraviolet (UV) wavelength (<400 nm) which is co-related with the deep-level defects. The growth and decay of the photocurrent is found to be slowest for the same film

Laser sintering of doped strontium aluminate via modified sol-gel for use as a ceramic pigment; Sinterizacao a laser do aluminato de estroncio dopado via sol-gel modificado para aplicacao como pigmento ceramico

Energy Technology Data Exchange (ETDEWEB)

Soares, F.M. dos S.; Valerio, M.E.G. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil)

2017-01-15

Powder of Dy{sup 3+} co-doped SrAl{sub 2}O{sub 4} :Eu{sup 3+} was produced via proteic sol-gel method, a modified sol-gel route which allows the formation of oxides at lower temperatures than other methods. CO{sub 2} laser sintering was used as a method for heat treatment, effective in reducing trivalent europium ions in doped samples. Thermal analysis of the precursors, performed by TG and DTA, revealed that the crystallization of SrAl{sub 2}O{sub 4} phase occurred at approximately 1060 °C. X-ray diffraction showed that the samples, before and after sintering, had monoclinic and hexagonal phases formation. DLS technique revealed the presence of nanosized and micrometric particles, and particle agglomerates, confirmed by SEM images. Micrographs of the fracture surface of a sintered pellet revealed a high degree of densification caused by heat treatment. Photoluminescence measurements showed that the samples after synthesis and before heat treatment with laser had reddish emission, composed of characteristic narrow emission lines from Eu{sup 3+} and more intense emission when the samples were excited at 265 nm. The laser treatment promoted the reduction of Eu{sup 3+} to Eu{sup 2+} and this effect was confirmed by the presence of a wide emission band in the green region of the spectrum with a maximum emission obtained after excitation at 350 nm. The luminescent decay time of the thermally treated sample was approximately 100 min. Via XRF measurements of acquired frit and DTA and TG of the frit, pigment and mixtures of both, it was noticed good compatibility in terms of thermal processes, that indicated that the pigment has a potential to be used in ceramic tiles. (author)

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

OpenAIRE

Musa Ahmad; T.W. Tan

2017-01-01

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to ...

Microwave characteristics of sol-gel based Ag-doped (Ba{sub 0.6}Sr{sub 0.4})TiO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyoung-Tae; Kim, Cheolbok [Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611 (United States); Senior, David E. [Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611 (United States); Department of Electrical and Electronic Engineering, Universidad Tecnológica de Bolívar Cartagena, 130011 Colombia (Colombia); Kim, Dongsu [Packaging Research Center, Korea Electronics Technology Institute, Gyeonggi-do, 463-816 (Korea, Republic of); Yoon, Yong-Kyu, E-mail: ykyoon@ece.ufl.edu [Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611 (United States)

2014-08-28

Dielectric Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films with a different concentration of Ag-dopant of 0.5, 1, 1.5, 2, 3, and 5 mol % have been prepared using an alkoxide-based sol-gel method on a Pt(111)/TiO{sub 2}/SiO{sub 2}/Si substrate and their surface morphology and crystallinity have been examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, respectively. An on-chip metal-insulator-metal capacitor has been fabricated with the prepared thin film ferroelectric sample. Concentric coplanar electrodes are used for high frequency electrical characterization with a vector network analyzer and a probe station. The SEM images show that increasing Ag doping concentration leads to a decrease in grain size. XRD reveals that the fabricated films show good BST crystallinity for all the concentration while a doping concentration of 5 mol % starts to show an Ag peak, implying a metallic phase. Improved microwave dielectric loss properties of the BST thin films are observed in a low Ag doping level. Especially, BST with an Ag doping concentration of 1 mol % shows the best properties with a dielectric constant of 269.3, a quality factor of 48.1, a tunability at the electric field of 100 kV/cm of 41.2 %, a leakage-current density of 1.045 × 10{sup −7}A/cm{sup 2} at an electric field of 100 kV/cm and a figure of merit (defined by tunability (%) divided by tan δ (%)) of 19.59 under a dc bias voltage of 10 V at 1 GHz. - Highlights: • High quality Ag-doped Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) thin films were derived by the sol-gel method. • Doped Ag replaced the A site ions in the ABO{sub 3} type structure. • Doped Ag helped lower leakage current by filling oxygen vacancies, which is a leakage path. • Microwave characteristics of low dielectric loss and good tunability were confirmed. • Great potential is envisioned for low loss tunable microwave applications.

Screen-printable sol-gel enzyme-containing carbon inks.

Science.gov (United States)

Wang, J; Pamidi, P V; Park, D S

1996-08-01

Enzymes usually cannot withstand the high-temperature curing associated with the thick-film fabrication process and require a separate immobilization step in connection with the production of single-use biosensors. We report on the development of sol-gel-derived enzyme-containing carbon inks that display compatibility with the screen-printing process. Such coupling of sol-gel and thick-film technologies offers a one-step fabrication of disposable enzyme electrodes, as it obviates the need for thermal curing. The enzyme-containing sol-gel carbon ink, prepared by dispersing the biocatalyst, along with the graphite powder and a binder, within the sol-gel precursors, is cured very rapidly (10 min) at low temperature (4 °C). The influence of the ink preparation conditions is explored, and the sensor performance is evaluated in connection with the incorporation of glucose oxidase or horseradish peroxidase. The resulting strips are stable for at least 3 months. Such sol-gel-derived carbon inks should serve as hosts for other heat-sensitive biomaterials in connection with the microfabrication of various thick-film biosensors.

Nanocrystalline sol-gel TiO{sub 2}-SnO{sub 2} coatings: Preparation, characterization and photo-catalytic performance

Energy Technology Data Exchange (ETDEWEB)

Kaleji, Behzad Koozegar [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Sarraf-Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

2012-02-15

Highlights: Black-Right-Pointing-Pointer SnO{sub 2} additive enhanced significantly photo-catalytic properties of TiO{sub 2} based thin film for remove of organic compounds. Black-Right-Pointing-Pointer Structural and optical properties are dependent on dopant concentration. Black-Right-Pointing-Pointer TiO{sub 2}-SnO{sub 2} nanocrystalline thin film is promising for photocatalytic properties in visible light. -- Abstract: In this study, preparation of SnO{sub 2} (0-30 mol% SnO{sub 2})-TiO{sub 2} dip-coated thin films on glazed porcelain substrates via sol-gel process has been investigated. The effects of SnO{sub 2} on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films were examined by atomic force microscopy and X-ray photoelectron spectroscopy. XRD patterns showed an increase in peak intensities of the rutile crystalline phase by increasing the SnO{sub 2} content. The prepared Sn doped TiO{sub 2} photo-catalyst films showed optical absorption in the visible light area exhibited excellent photo-catalytic ability for the degradation of methylene blue under visible light irradiation. Best photo-catalytic activity of Sn doped TiO{sub 2} thin films was measured in the TiO{sub 2}-15 mol% SnO{sub 2} sample by the Sn{sup 4+} dopants presented substitution Ti{sup 4+} into the lattice of TiO{sub 2} increasing the surface oxygen vacancies and the surface hydroxyl groups.

Silica Sol-Gel Entrapment of the Enzyme Chloro peroxidase

International Nuclear Information System (INIS)

Le, T.; Chan, S.; Ebaid, B.; Sommerhalter, M.

2015-01-01

The enzyme chloro peroxidase (CPO) was immobilized in silica sol-gel beads prepared from tetramethoxysilane. The average pore diameter of the silica host structure (∼3 nm) was smaller than the globular CPO diameter (∼6 nm) and the enzyme remained entrapped after sol-gel maturation. The catalytic performance of the entrapped enzyme was assessed via the pyrogallol peroxidation reaction. Sol-gel beads loaded with 4 μg CPO per mL sol solution reached 9-12% relative activity compared to free CPO in solution. Enzyme kinetic analysis revealed a decrease in K_cat but no changes in K_M or K_I . Product release or enzyme damage might thus limit catalytic performance. Yet circular dichroism and visible absorption spectra of transparent CPO sol-gel sheets did not indicate enzyme damage. Activity decline due to methanol exposure was shown to be reversible in solution. To improve catalytic performance the sol-gel protocol was modified. The incorporation of 5, 20, or 40% methyltrimethoxysilane resulted in more brittle sol-gel beads but the catalytic performance increased to 14% relative to free CPO in solution. The use of more acidic casting buffers (ph 4.5 or 5.5 instead of 6.5) resulted in a more porous silica host reaching up to 18% relative activity

Optical characterization of Er-implanted ZnO films formed by sol-gel method

International Nuclear Information System (INIS)

Fukudome, T.; Kaminaka, A.; Isshiki, H.; Saito, R.; Yugo, S.; Kimura, T.

2003-01-01

In this paper, we report on the 1.54 μm photoluminescence (PL) of Er-implanted ZnO thin films formed by a sol-gel method on Si substrates. In spite of the polycrystalline structure of the sol-gel ZnO thin films, they showed strong PL emissions due to the near band edge recombination at 375 nm as well as the Er-related luminescence at 1.54 μm. The Er-related luminescence showed no decrease (quench) in the intensity up to the Er concentration of 1.5 x 10 21 cm -3 . The PL intensity of Er-implanted ZnO at 1.54 μm was found to be as strong as Er-doped PS (porous Si) at 20 K, and the intensity reduced to 1/3 at room temperature

Corrosion electrochemical behaviors of silane coating coated magnesium alloy in NaCl solution containing cerium nitrate

Energy Technology Data Exchange (ETDEWEB)

Luo, F.; Li, Q.; Zhong, X.K.; Gao, H.; Dai, Y.; Chen, F.N. [School of Chemistry and Chemical Engineering, Southwest University Chongqing (China)

2012-02-15

Sol-gel coatings cannot provide adequate corrosion protection for metal/alloys in the corrosive environments due to their high crack-forming potential. This paper demonstrates the possibility to employ cerium nitrate as inhibitor to decrease the corrosion development of sol-gel-based silane coating on the magnesium alloy in NaCl solution. Cerium nitrate was added into the NaCl solution where the silane coating coated magnesium alloy was immersed. Scanning electron microscopy (SEM) was used to examine surface morphology of the silane coating coated magnesium alloy immersed in NaCl solutions doped and undoped with cerium nitrate. The corrosion electrochemical behaviors were investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The results showed that the introduction of cerium nitrate into NaCl solution could effectively inhibit the corrosion of the silane coating coated magnesium alloy. Moreover, the influence of concentration of cerium nitrate on the corrosion inhibition and the possible inhibiting mechanism were also discussed in detail. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sol-gel method for encapsulating molecules

Science.gov (United States)

Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

2002-01-01

A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

Science.gov (United States)

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

2010-01-01

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

Construction of flame retardant coating on polyamide 6.6 via UV grafting of phosphorylated chitosan and sol-gel process of organo-silane.

Science.gov (United States)

Kundu, Chanchal Kumar; Wang, Xin; Hou, Yanbei; Hu, Yuan

2018-02-01

Phosphorylated chitosan (PCS) was synthesized and grafted onto the surface of polyamide 6.6 (PA 6.6) fabrics via UV-induced grafting polymerization in order to improve the flame retardant properties. Subsequently, PCS grafted PA 6.6 fabrics were modified by (3-aminopropyl) triethoxysilane (APTES) through sol-gel process in order to form a cross-linking coating. The results obtained from the vertical burning test indicated that only the PCS grafted and simultaneously sol-gel treated fabrics could stop the melt dripping. A maximum reduction (30%) in the peak heat release rate was achieved for the PA6.6-PCS-4W-SG fabric sample. The optimal flame retardant effect was achieved for the PA6.6 fabrics treated by PCS and APTES simultaneously, which was attributed to the joint effect of thermal shielding exerted by the silica and char-forming effect derived from PCS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Holographic sol-gel monoliths: optical properties and application for humidity sensing

Science.gov (United States)

Ilatovskii, Daniil A.; Milichko, Valentin; Vinogradov, Alexander V.; Vinogradov, Vladimir V.

2018-05-01

Sol-gel monoliths based on SiO2, TiO2 and ZrO2 with holographic colourful diffraction on their surfaces were obtained via a sol-gel synthesis and soft lithography combined method. The production was carried out without any additional equipment at near room temperature and atmospheric pressure. The accurately replicated wavy structure with nanoscale size of material particles yields holographic effect and its visibility strongly depends on refractive index (RI) of materials. Addition of multi-walled carbon nanotubes (MWCNTs) in systems increases their RI and lends absorbing properties due to extremely high light absorption constant. Further prospective and intriguing applications based on the most successful samples, MWCNTs-doped titania, were investigated as reversible optical humidity sensor. Owing to such property as reversible resuspension of TiO2 nanoparticles while interacting with water, it was proved that holographic xerogels can repeatedly act as humidity sensors. Materials which can be applied as humidity sensors in dependence on holographic response were discovered for the first time.

Iron specificity of a biosensor based on fluorescent pyoverdin immobilized in sol-gel glass

Science.gov (United States)

2011-01-01

Two current technologies used in biosensor development are very promising: 1. The sol-gel process of making microporous glass at room temperature, and 2. Using a fluorescent compound that undergoes fluorescence quenching in response to a specific analyte. These technologies have been combined to produce an iron biosensor. To optimize the iron (II or III) specificity of an iron biosensor, pyoverdin (a fluorescent siderophore produced by Pseudomonas spp.) was immobilized in 3 formulations of porous sol-gel glass. The formulations, A, B, and C, varied in the amount of water added, resulting in respective R values (molar ratio of water:silicon) of 5.6, 8.2, and 10.8. Pyoverdin-doped sol-gel pellets were placed in a flow cell in a fluorometer and the fluorescence quenching was measured as pellets were exposed to 0.28 - 0.56 mM iron (II or III). After 10 minutes of exposure to iron, ferrous ion caused a small fluorescence quenching (89 - 97% of the initial fluorescence, over the range of iron tested) while ferric ion caused much greater quenching (65 - 88%). The most specific and linear response was observed for pyoverdin immobilized in sol-gel C. In contrast, a solution of pyoverdin (3.0 μM) exposed to iron (II or III) for 10 minutes showed an increase in fluorescence (101 - 114%) at low ferrous concentrations (0.45 - 2.18 μM) while exposure to all ferric ion concentrations (0.45 - 3.03 μM) caused quenching. In summary, the iron specificity of pyoverdin was improved by immobilizing it in sol-gel glass C. PMID:21554740

Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

Science.gov (United States)

Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

2015-05-01

In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of annealing temperature on optical properties of Al doped ZnO nanoparticles via sol-gel methods

Science.gov (United States)

Rashid, Affa Rozana Abd; Hazwani, Tuan Nur; Mukhtar, Wan Maisarah; Taib, Nur Athirah Mohd

2018-06-01

Zinc oxide (ZnO) thin films have become technologically important materials due to their wide range of electrical and optical properties. The characteristics can be further adjusted by adequate doping processes. The effect of dopant concentration of Al, heating treatment and annealing in reducing atmosphere on the optical properties of the thin films is discussed. Undoped and aluminum-doped zinc oxide (AZO) thin films are prepared by the sol-gel method. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine are used as precursor, solvent and stabilizer. In the case of AZO, aluminum nitrate nanohydrate is added to the precursor solution with an atomic percentage equal to 0 %, 1 %, 2 % and 3 % of Al. The multi thin layers are transformed into ZnO upon annealing at 450 °C and 500 °C. The optical properties such as transmittance, absorbance, band gap and refractive index of the thin films have been investigated by using UV-Visible Spectroscopy (UV-Vis). The results show that the effect of aluminium dopant concentration on the optical properties is depend on the post-heat treatment of the films. By doping with Al, the transmittance spectra in visible range increased and widen the band gap of ZnO which might due to Burstein-moss effects.

Preparation of sol-gel TiO2/purified Na-bentonite composites and their photovoltaic application for natural dye-sensitized solar cells

International Nuclear Information System (INIS)

Saelim, Ni-on; Magaraphan, Rathanawan; Sreethawong, Thammanoon

2011-01-01

Highlights: → Natural dye from red cabbage was successfully employed in DSSC. → A fast sol-gel method to produce TiO 2 /clay thin film was proposed. → The sol-gel-prepared TiO 2 /clay was applied as the scattering layer on top of TiO 2 electrode. → Thicker sol-gel-prepared TiO 2 /clay electrode showed higher DSSC efficiency. - Abstract: The sol-gel TiO 2 /purified natural clay electrodes having Ti:Si molar ratios of 95:5 and 90:10 were initially prepared, sensitized with natural red cabbage dye, and compared to the sol-gel TiO 2 electrode in terms of physicochemical characteristics and solar cell efficiency. The results showed that the increase in purified Na-bentonite content greatly increased the specific surface area and total pore volume of the prepared sol-gel TiO 2 /purified Na-bentonite composites because the clay platelets prevented TiO 2 particle agglomeration. The sol-gel TiO 2 /5 mol% Si purified Na-bentonite and sol-gel TiO 2 /10 mol% Si purified Na-bentonite composites could increase the film thickness of solar cells without cracking when they were coated as a scattering layer on the TiO 2 semiconductor-based film, leading to increasing the efficiency of the natural dye-sensitized solar cells in this work.

Silica-sol-based spin-coating barrier layer against phosphorous diffusion for crystalline silicon solar cells.

Science.gov (United States)

Uzum, Abdullah; Fukatsu, Ken; Kanda, Hiroyuki; Kimura, Yutaka; Tanimoto, Kenji; Yoshinaga, Seiya; Jiang, Yunjian; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ito, Seigo

2014-01-01

The phosphorus barrier layers at the doping procedure of silicon wafers were fabricated using a spin-coating method with a mixture of silica-sol and tetramethylammonium hydroxide, which can be formed at the rear surface prior to the front phosphorus spin-on-demand (SOD) diffusion and directly annealed simultaneously with the front phosphorus layer. The optimization of coating thickness was obtained by changing the applied spin-coating speed; from 2,000 to 8,000 rpm. The CZ-Si p-type silicon solar cells were fabricated with/without using the rear silica-sol layer after taking the sheet resistance measurements, SIMS analysis, and SEM measurements of the silica-sol material evaluations into consideration. For the fabrication of solar cells, a spin-coating phosphorus source was used to form the n(+) emitter and was then diffused at 930°C for 35 min. The out-gas diffusion of phosphorus could be completely prevented by spin-coated silica-sol film placed on the rear side of the wafers coated prior to the diffusion process. A roughly 2% improvement in the conversion efficiency was observed when silica-sol was utilized during the phosphorus diffusion step. These results can suggest that the silica-sol material can be an attractive candidate for low-cost and easily applicable spin-coating barrier for any masking purpose involving phosphorus diffusion.

Thermal properties and water repellency of cotton fabric prepared through sol-gel method

Directory of Open Access Journals (Sweden)

Gu Jia-Li

2016-01-01

Full Text Available Cotton fabrics were treated by one-step sol-gel method. The pure silica hydrosol and phosphorus-doped hydrosol were prepared with the addition of a hydrophobic hexadecyltrimethoxysilane to decrease the surface energy of cotton fabric. The thermal properties and water repellency of treated cotton fabric were characterized by thermo-gravimetric analysis, micro combustion, limiting oxygen index, and contact angle measurement. The results showed that cotton fabric treated by phosphorus-doped silica hydrosol had excellent flame retardance, and the water repellence was apparently improved with the addition of hexadecyltrimethoxysilane.

Spatially resolved speckle-correlometry of sol-gel transition

Science.gov (United States)

Isaeva, A. A.; Isaeva, E. A.; Pantyukov, A. V.; Zimnyakov, D. A.

2018-04-01

Sol-gel transition was studied using the speckle correlometry method with a localized light source and spatial filtering of backscattered radiation. Water solutions of technical or food gelatin with added TiO2 nanoparticles were used as studied objects. Structural transformation of "sol-gel" system was studied at various temperatures from 25°C to 50°C using analysis of the correlation and structure functions of speckle intensity fluctuations. The characteristic temperatures of "sol - gel" transition were evaluated for studied systems. Obtained results can be used for various applications in biomedicine and food industry.

Luminescence properties of europium (III) cryptates trapped in sol-gel glass

International Nuclear Information System (INIS)

Zaitoun, M.A.; Kim, T.; Jaradat, Q.M.; Momani, K.; Qaseer, H.A.; El-Qisairi, A.K.; Qudah, A.; Radwan, N.E.

2008-01-01

The Lanthanide complexes Eu-2.2.1 and Eu-2.2.2 were synthesized and then incorporated into silica based transparent organic-inorganic hybrid material by the sol-gel method as an example of how doped xerogel materials are emerging as an important means of producing new materials. The produced gels were diagnosed to monitor emission spectra of the luminescent trivalent europium (Eu 3+ ) complexes; emissions were compared to those for gels containing uncomplexed Eu 3+ . Results of the experiments (emission and lifetimes) concerning the coordination sphere composition showed that a cryptand ligand with aromatic groups (short range effect) and the hydrophobic gel host (long range effect) settle efficient action in the antenna effect and isolate the central ion from efficient quenchers, as e.g. water molecules. Each ligand imposed a distinct splitting pattern on the europium emission bands that helps identify them

New insights into uranium (VI) sol-gel processing

International Nuclear Information System (INIS)

King, C.M.; Thompson, M.C.; Buchanan, B.R.; King, R.B.; Garber, A.R.

1990-01-01

Nuclear Magnetic Resonance (NMR) investigations on the Oak Ridge National Laboratory process for sol-gel synthesis of microspherical nuclear fuel (UO 2 ), has been extremely useful in sorting out the chemical mechanism in the sol-gel steps. 13 C, 15 N, and 1 H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C 6 H 12 N 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. 17 O NMR of uranyl (UO 2 ++ ) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO 2 ) 3 (μ 3 -O)(μ 2 -OH) 3 ] + , 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 + 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 4 ) 2 [(UO 2 ) 8 O 4 (OH) 10 ] · 8H 2 O. This compound is the precursor to sintered UO 2 ceramic fuel. 23 refs., 10 figs

Preparation and characterization of ZnO transparent semiconductor thin films by sol-gel method

International Nuclear Information System (INIS)

Tsay, Chien-Yie; Fan, Kai-Shiung; Chen, Sih-Han; Tsai, Chia-Hao

2010-01-01

Transparent semiconductor thin films of zinc oxide (ZnO) were deposited onto alkali-free glass substrates by the sol-gel method and spin-coating technique. In this study, authors investigate the influence of the heating rate of the preheating process (4 or 10 o C/min) on the crystallization, surface morphology, and optical properties of sol-gel derived ZnO thin films. The ZnO sol was synthesized by dissolving zinc acetate dehydrate in ethanol, and then adding monoethanolamine. The as-coated films were preheated at 300 o C for 10 min and annealed at 500 o C for 1 h in air ambiance. Experimental results indicate that the heating rate of the preheating process strongly affected the surface morphology and transparency of ZnO thin film. Specifically, a heating rate of 10 o C/min for the preheating process produces a preferred orientation along the (0 0 2) plane and a high transmittance of 92% at a wavelength of 550 nm. Furthermore, this study reports the fabrication of thin-film transistors (TFTs) with a transparent ZnO active channel layer and evaluates their electrical performance.

Incorporation of sol-gel SnO2:Sb into nanoporous SiO2

International Nuclear Information System (INIS)

Canut, B.; Blanchin, M.G.; Ramos-Canut, S.; Teodorescu, V.; Toulemonde, M.

2006-01-01

Silicon oxide films thermally grown on Si(1 0 0) wafers were irradiated with 200 MeV 197 Au ions in the 10 9 -10 1 cm -2 fluence range. The targets were then etched at room temperature in aqueous HF solution (1 vol.%) for various durations. Atomic force microscopy (AFM) in the tapping mode was used to probe the processed surfaces. Conical holes with a low size dispersion were evidenced. Their surface diameter varies between 20 and 70 nm, depending on the etching time. Sol-gel dip coating technique, associated with a further annealing treatment performed at 500 o C for 15 min, was used to fill the nanopores created in SiO 2 with a transparent conductive oxide (SnO 2 doped with antimony). Transmission electron microscopy (TEM) performed on cross-sectional specimen showed that SnO 2 :Sb crystallites of ∼5 nm mean size are trapped in the holes without degrading their geometry

Applicability of Sol-Gel Derived Adsorbent for the Production of (n,f) 99Mo Generator

International Nuclear Information System (INIS)

Lee, Jun-Sig; Lee, Jong-Sup; Park, Ul-Jae; Son, Kwang-Jae; Han, Hyon-Soo; Kim, Myung Sic; Koo, Sung Chan; Chung, Young-Ju

2007-01-01

High performance adsorbents as the column material for (n,γ) 99 Mo/ 99 mTc and 188 W/ 188 Re generators have been developed at KAERI. These adsorbents should have enough loading capacities to produce such generators with high activities as the loading isotopes are not carrier-free. In this regard, the adsorbents are synthesized by sol-gel processing in which the ligand density can easily be adjusted and maximized. The marginal capacity of such adsorbents should be higher than 200 mg/g for molybdenum. From the previous works, the sol-gel processing techniques are adequately applied to meet the criteria. Further studies are being undertaken to employ the adsorbents for the production of high capacity (n,f) 99 Mo/ 99 mTc. Domestically, a private company has lined up the production facility of the molybdenum generator in the activity range of 300 ∼ 1,000 mCi/ea. The column elements are composed of manganese oxide doped on silica and alumina at the backup layer. In this column, the manganese oxide is the main reactive layer to retain (n,f) 99 Mo. The sol-gel derived adsorbent, in this study, is employed as the replacement of the manganese oxide doped silica in the column and tested for the loading efficiency of (n,f) 99 Mo, elution of 99 mTc, labeling property of the eluted 99 mTc. The same loading and elution procedures as the commercial production are applied for the tests and quality controls

Luminescence enhancement in Eu3+, Sm3+ co-doped liy(MoO4)2 nano-phosphors by sol-gel process.

Science.gov (United States)

Zhou, Xianju; Wang, Guangchuan; Zhou, Tonghui; Zhou, Kaining; Li, Qingxu; Wang, Zhongqing

2014-05-01

A series of LiY(0.95-x)Eu(0.05)Sm(x)(MoO4)2 red light emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray Diffraction (XRD), Photo-Luminescence (PL) and Photo-Luminescence Excitation (PLE) spectra, respectively. It is found that the PLE spectra of the Eu3+, Sm3+ co-doped nanoparticles are enhanced and broadened as compared with the solely doped samples, which will make the co-doped phosphors match better with blue and/or UV GaN based LED chips. The red emission intensity of Eu3+ is largely enhanced by the energy transfer from Sm3+. The mechanism of the enhancement is clearly proven to be the increase in the quantum efficiency of 5D0 state of Eu3+ rather than the increase in the absorption of Eu3+. Meanwhile, the characteristic f-f transitions of Sm3+ are greatly reduced, resulting in little influence in the color purity of the co-doped phosphors. The present material is an amendatory promising red light emitting phosphor for white LEDs.

Photocatalytic Graphene-TiO2 Thin Films Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray Coating in a Sol-Gel Process

Directory of Open Access Journals (Sweden)

Fatemeh Zabihi

2017-05-01

Full Text Available In this work, we communicate a facile and low temperature synthesis process for the fabrication of graphene-TiO2 photocatalytic composite thin films. A sol-gel chemical route is used to synthesize TiO2 from the precursor solutions and spin and spray coating are used to deposit the films. Excitation of the wet films during the casting process by ultrasonic vibration favorably influences both the sol-gel route and the deposition process, through the following mechanisms. The ultrasound energy imparted to the wet film breaks down the physical bonds of the gel phase. As a result, only a low-temperature post annealing process is required to eliminate the residues to complete the conversion of precursors to TiO2. In addition, ultrasonic vibration creates a nanoscale agitating motion or microstreaming in the liquid film that facilitates mixing of TiO2 and graphene nanosheets. The films made based on the above-mentioned ultrasonic vibration-assisted method and annealed at 150 °C contain both rutile and anatase phases of TiO2, which is the most favorable configuration for photocatalytic applications. The photoinduced and photocatalytic experiments demonstrate effective photocurrent generation and elimination of pollutants by graphene-TiO2 composite thin films fabricated via scalable spray coating and mild temperature processing, the results of which are comparable with those made using lab-scale and energy-intensive processes.

Preparation and Scintillating Properties of Sol-Gel Eu3+, Tb3+ Co-Doped Lu2O3 Nanopowders

Directory of Open Access Journals (Sweden)

Joel Moreno Palmerin

2011-09-01

Full Text Available Nanocrystalline Eu3+, Tb3+ co-doped Lu2O3 powders with a maximum size of 25.5 nm were prepared by the sol-gel process, using lutetium, europium and terbium nitrates as precursors, and ethanol as a solvent. Differential thermal analysis (DTA and infrared spectroscopy (IR were used to study the chemical changes during the xerogel annealing. After the sol evaporation at 100 °C, the formed gel was annealed from 300 to 900 °C for 30 min under a rich O2 atmosphere, and the yielded product was analyzed by X-ray diffraction (XRD to characterize the microstructural behavior and confirm the crystalline structure. The results showed that Lu2O3 nanopowders start to crystallize at 400 °C and that the crystallite size increases along with the annealing temperature. A transmission electron microscopy (TEM study of samples annealed at 700 and 900 °C was carried out in order to analyze the microstructure, as well as the size, of crystallites. Finally, in regard to scintillating properties, Eu3+ dopant (5 mol%, Tb3+ codoped Lu2O3 exhibited a typical red emission at 611 nm (Do→7F2, furthermore, the effect of Tb3+ molar content (0.01, 0.015 and 0.02% mol on the Eu3+ radioluminiscence was analyzed and it was found that the higher emission intensity corresponds to the lower Tb3+ content.

Structural Evolution and Stability of Sol-Gel Biocatalysts

International Nuclear Information System (INIS)

Rodgers, L.E.; Foster, L.J.R.; Holden, P.J.; Knott, R.B.; Bartlett, J.B.

2005-01-01

Full text: Immobilisation strategies for catalytic enzymes are important as they allow reuse of the biocatalysts. Sol-gel materials have been used to immobilise Candida antarctica lipase B (CALB), a commonly used industrial enzyme with a known crystal structure. The sol-gel bioencapsulate is produced through the condensation of suitable metal alkoxides in the presence of CALB, yielding materials with controlled pore sizes, volume and surface chemistry. Sol-gel matrices have been shown to 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 analysis techniques applied to date. Small angle neutron scattering (SANS) allows such multicomponent 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 percent. 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. The SANS protocol developed here may be applied more generally to bioencapsulates. (authors)

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

Directory of Open Access Journals (Sweden)

Musa Ahmad

2017-11-01

Full Text Available An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

Enhance the Pyroelectricity of Polyvinylidene Fluoride by Graphene-Oxide Doping

Directory of Open Access Journals (Sweden)

Yuh-Chung Hu

2014-04-01

Full Text Available The high quality properties and benefits of graphene-oxide have generated an active area of research where many investigations have shown potential applications in various technological fields. This paper proposes a methodology for enhancing the pyro-electricity of PVDF by graphene-oxide doping. The PVDF film with graphene-oxide is prepared by the sol-gel method. Firstly, PVDF and graphene-oxide powders are dispersed into dimethylformamide as solvent to form a sol solution. Secondly, the sol solution is deposited on a flexible ITO/PET substrate by spin-coating. Thirdly, the particles in the sol solution are polymerized through baking off the solvent to produce a gel in a state of a continuous network of PVDF and graphene-oxide. The final annealing process pyrolyzes the gel and form a β-phase PVDF film with graphene-oxide doping. A complete study on the process of the graphene oxide doping of PVDF is accomplished. Some key points about the process are addressed based on experiments. The solutions to some key issues are found in this work, such as the porosity of film, the annealing temperature limitation by the use of flexible PET substrate, and the concentrations of PVDF and graphene-oxide.

Effects of cobalt doping on structural, morphological, and optical properties of Zn2SiO4 nanophosphors prepared by sol-gel method

Directory of Open Access Journals (Sweden)

Norhafizah Mohd Rasdi

Full Text Available In this paper, undoped and cobalt (II (3, and 5 mol % doped zinc silicate nanophosphors prepared by a sol-gel method which were heated at 1000 °C were studied in detail. From the XRD result, undoped and Co2+ doped zinc silicate sample yields α- and β-Zn2SiO4. This also shows that α-Zn2SiO4 acts as the primary phase in the crystal structure of the sample. For FESEM, the grain size decreases as the dopant increases where undoped sample indicates average grain size of 181 nm while 3 and 5 mol % exhibits containing ones 136.89 nm and 176.22 nm respectively. With FTIR transmission a major peak at range of 1100 cm−1, 880, 550, and 350 assigning as Si-O-Si asymmetric stretching, SiO4 asymmetric stretching, ZnO4 symmetric stretching, and Si-O asymmetric deformation vibration were observed respectively. The absorption band of doped Zn2SiO4 exhibited a higher absorbance intensity in the UV region compared to undoped Zn2SiO4. Besides, all the samples depict that the sample was having a red shift in which the band shifted to the longer wavelength. The energy band gap value of undoped sample shows 3.07 eV and when Co2+ dopant (3 and 5 mol % was introduced, the energy band gap started to decrease (2.46 and 2.42 eV respectively. PL emission presents two peaks at blue emissions (420 and 480 nm and a green emission (525 nm. The result present that Co2+:Zn2SiO4 is potentially good to use as blue and green phosphors for luminescent optical material. Keywords: Cobalt (II doped zinc silicate, Transition metal, Sol-gel method, Nanophosphors, Photoluminescence

Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

International Nuclear Information System (INIS)

Luna, F. Perdomo; Atik, M.; Avaca, Luis A.; Aegerter, M.A.

1995-01-01

Zr O 2 thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C 3 H 7 )4/C 3 H 7 OH = 0.5), glacial acetic acid and water (C H 3 CO OH/H 2 O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 μm. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H 2 SO 4 at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7

Formation and characterization of vitreous materials prepared by the sol-gel technique

International Nuclear Information System (INIS)

Martinez, J.R.; Ruiz, J.F.; Cruz M, J.A. de la; Villasenor G, P.

1999-01-01

A full process of preparation and characterization of silica gel, which can be implemented in a experimental course for undergraduate laboratories is presented. Samples of silica gel and sol-gel derived SiO 2 films on glass substrates were fabricated and characterized using atomic force microscopy, Raman and Infrared absorption techniques. Raman and Infrared spectroscopy were used to analyze the local structure. The microstructure characteristics of the films, fabricated by dip-coating, were monitored using atomic force microscopy. The samples were prepared from alcoholic solutions of tetraethylortosilicate (TEOS) keeping the H 2 O/TEOS and Et-OH/TEOS molar ratios constant and equal to 11.66 and 4 respectively. (Author)

Response of SAOS-2 cells to simulated microgravity and effect of biocompatible sol-gel hybrid coatings

Science.gov (United States)

Catauro, M.; Bollino, F.; Papale, F.

2016-05-01

The health of astronauts, during space flight, is threatened by bone loss induced by microgravity, mainly attributed to an imbalance in the bone remodeling process. In the present work, the response to the microgravity of bone cells has been studied using the SAOS-2 cell line grown under the condition of weightlessness, simulated by means of a Random Positioning Machine (RPM). Cell viability after 72 h of rotation has been evaluated by means of WST-8 assay and compared to that of control cells. Although no significant difference between the two cell groups has been observed in terms of viability, F-actin staining showed that microgravity environment induces cell apoptosis and altered F-actin organization. To investigate the possibility of hindering the trend of the cells towards the death, after 72 h of rotation the cells have been seeded onto biocompatible ZrO2/PCL hybrid coatings, previously obtained using a sol-gel dip coating procedure. WST-8 assay, carried out after 24 h, showed that the materials are able to inhibit the pro-apoptotic effect of microgravity on cells.

Luminescence and circularly polarized luminescence of macrocyclic Eu(III) and Tb(III) complexes embedded in xerogel and sol-gel SiO2 glasses

International Nuclear Information System (INIS)

Morita, M.; Rau, D.; Kai, T.

2002-01-01

Luminescence, time-resolved luminescence, circularly polarized luminescence (CPL) and decay profiles of Ln(III)(15-crownether-5) (Ln=Ce, Sm, Eu, Tb) and Tb(III)-(R),(S)-cyclen derivative complexes doped in xerogel and sol-gel silica glasses are measured at temperatures down to 10 K to characterize luminescence properties and the electronic structure in the excited states. Luminescence spectral profiles and calculation of crystal field parameters (B 0 (2) ,B 2 (2) ) in the 5 D 0 → 7 F J (J=1,2) transition give evidence of the fact that the pentagonal and planar structure of Eu(III) (15-crownether-5) does hold in xerogel and sol-gel glasses prepared at temperatures below 100 deg. C. As annealing temperatures are increased from 80 deg. C to 750 deg. C, Eu(III) complexes in sol-gel glasses are found to decompose gradually to SiO 2 :Eu 3+ . Tb(III)-(R) and (S)-cyclen derivative complexes in xerogel reveal at room temperature and 10 K sharp CPL spectra with luminescence dissymmetry factors g lum =-0.1 and 0.1, respectively. These complexes doped in sol-gel glasses represent luminescence characteristics of rare earth ions encapsulated in the nano-porous host

Separation of oligopeptides, nucleobases, nucleosides and nucleotides using capillary electrophoresis/electrochromatography with sol-gel modified inner capillary wall.

Science.gov (United States)

Svobodová, Jana; Kofroňová, Olga; Benada, Oldřich; Král, Vladimír; Mikšík, Ivan

2017-09-29

The aim of this article is to study the modification of an inner capillary wall with sol-gel coating (pure silica sol-gel or silica sol-gel containing porphyrin-brucine conjugate) and determine its influence on the separation process using capillary electrophoresis/electrochromatography method. After modification of the inner capillary surface the separation of analytes was performed using two different phosphate buffers (pH 2.5 and 9.0) and finally the changes in electrophoretic mobilities of various samples were calculated. To confirm that the modification of the inner capillary surface was successful, the parts of the inner surfaces of capillaries were observed using scanning electron microscopy. The analytes used as testing samples were oligopeptides, nucleosides, nucleobases and finally nucleotides. Copyright © 2017 Elsevier B.V. All rights reserved.

Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

Science.gov (United States)

Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

2016-01-01

The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and Pcoating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain.

Effect of TiO2/Al2O3 film coated diamond abrasive particles by sol-gel technique

Science.gov (United States)

Hu, Weida; Wan, Long; Liu, Xiaopan; Li, Qiang; Wang, Zhiqi

2011-04-01

The diamond abrasive particles were coated with the TiO2/Al2O3 film by the sol-gel technique. Compared with the uncoated diamonds, the TiO2/Al2O3 film was excellent material for the protection of the diamonds. The results showed that the incipient oxidation temperature of the TiO2/Al2O3 film coated diamonds in air atmosphere was 775 °C, which was higher 175 °C than that of the uncoated diamonds. And the coated diamonds also had better the diamond's single particle compressive strength and the impact toughness than that of uncoated diamonds after sintering at 750 °C. For the vitrified bond grinding wheels, replacing the uncoated diamonds with the TiO2/Al2O3 film coated diamonds, the volume expansion of the grinding wheels decreased from 6.2% to 3.4%, the porosity decreased from 35.7% to 25.7%, the hardness increased from 61.2HRC to 66.5HRC and the grinding ratio of the vitrified bond grinding wheels to carbide alloy (YG8) increased from 11.5 to 19.1.

Characterization of selenium doped silica glasses synthesized by sol-gel method

International Nuclear Information System (INIS)

Kobayashi, R.A.; Toffoli, S.M.

2012-01-01

Selenium is a rare element in nature. It is used in the food, pharmaceutical, and glass industries. In commercial glasses, selenium is the element responsible for most of the pink or light red color, but its effect is primarily dependent on the oxidation state of the element in the glassy matrix. Besides, selenium is highly volatile, and as high as 80 wt% may be lost in the furnace during the industrial glass elaboration. The sol– gel method yields synthesized materials of high purity and homogeneity, and uses low processing temperatures. Samples of silica glass were obtained by sol-gel method, incorporating precursors of selenium, with the main objective of reducing selenium losses during its heating. The results of optical absorption, XRD and thermal analysis (TGA, DSC) of the glasses are presented and discussed. (author)

Influencia del tratamiento térmico sobre el espesor y porosidad de películas delgadas de ZrO2 obtenidas por la ruta sol-gel

Directory of Open Access Journals (Sweden)

Caruso, R.

2004-04-01

Full Text Available The present work is aimed to investigate the thermal densification mechanisms of sol-gel zirconia thin films deposited by dip coating, with particular emphasis on thickness and porosity evolution at different firing treatments (100-1100ºC. For this purpose, we have only used data from transmission spectrum. Implications for controlled design of sol-gel zirconia films will be considered.El este trabajo se investigan los mecanismos de densificación de películas delgadas de zirconia obtenidas por vía sol-gel y depositadas mediante la técnica dip-coating. Nuestro interés se centra en la determinación del espesor y porosidad de películas tratadas a temperaturas en el rango 100-1100 ºC. Para ello, se ha utilizado exclusivamente la técnica de espectrofotometría. Los resultados de este trabajo tienen interés para el diseño controlado de recubrimientos sol-gel de ZrO2.

Manufacture of amorphous and poly-crystalline materials with the sol-gel process; Fabricacion de materiales amorfos y policristalinos con la ruta sol-gel

Energy Technology Data Exchange (ETDEWEB)

Castaneda-Contreras, J. [Centro Universitario de Los Lagos, Universidad de Guadalajara, Guadalajara, Jalisco (Mexico)

2006-01-15

The sun-gel process is a chemical route that allows the manufacture of amorphous and poly-crystalline materials in a relatively simple way. New materials can be obtained, materials that through the traditional manufacture methods, are very difficult to obtain, such as oxide combinations (SiO{sub 2}, TiO{sub 2}, ZrO{sub 2}, etc.), and that, when being produced by traditional methods, they run the risk of being contaminated with rare earth ions or organic dyes. The unique structures, micro- structures and compounds that can be made with the sun-gel process open many possibilities for practical applications, to name a few: the manufacture of optical components, preforms for optical fibers, dielectric coatings, superconductors, waveguides, nanoparticles, solar cells, etc. [Spanish] El proceso sol-gel es una ruta quimica que permite fabricar materiales amorfos y policristalinos de forma relativamente sencilla. Se pueden obtener nuevos materiales que a traves de los metodos tradicionales de fabricacion son muy dificiles de obtener, tales como combinaciones de oxidos (SiO{sub 2}, TiO{sub 2}, ZrO{sub 2}, etc.), y que, de ser producidos por metodos tradicionales corren el riesgo de contaminarse con iones de tierras raras o colorantes organicos. Las estructuras unicas, micro estructuras y compuestos que pueden hacerse con el proceso sol-gel abren muchas posibilidades para aplicaciones practicas, por nombrar algunas, la fabricacion de componentes opticos, preformas para fibras opticas, recubrimientos dielectricos, superconductores, guias de onda, nanoparticulas, celdas solares, etc.

Enhanced optical band-gap of ZnO thin films by sol-gel technique

Energy Technology Data Exchange (ETDEWEB)

Raghu, P., E-mail: dpr3270@gmail.com; Naveen, C. S.; Shailaja, J.; Mahesh, H. M., E-mail: hm-mahesh@rediffmail.com [Thin Film and Solar Cell Laboratory, Department of Electronic Science, Bangalore University, Jnanabharathi, Bangalore -560056 (India)

2016-05-06

Transparent ZnO thin films were prepared using different molar concentration (0.1 M, 0.2 M & 0.8 M) of zinc acetate on soda lime glass substrates by the sol-gel spin coating technique. The optical properties revealed that the transmittance found to decrease with increase in molar concentration. Absorption edge showed that the higher concentration film has increasingly red shifted. An increased band gap energy of the thin films was found to be direct allowed transition of ∼3.9 eV exhibiting their relevance for photovoltaic applications. The extinction coefficient analysis revealed maximum transmittance with negligible absorption coefficient in the respective wavelengths. The results of ZnO thin film prepared by sol-gel technique reveal its suitability for optoelectronics and as a window layer in solar cell applications.

Effect of Mn doping on the structural, magnetic, optical and electrical properties of ZrO_2–SnO_2 thin films prepared by sol–gel method

International Nuclear Information System (INIS)

Anitha, V.S.; Sujatha Lekshmy, S.; Joy, K.

2016-01-01

Manganese doped ZrO_2–SnO_2 (ZrO_2–SnO_2: Mn) nanocomposite thin films were prepared using sol – gel dip coating technique. The structural, morphological, magnetic, optical and electrical properties of the films were studied for undoped and different (15 mol %) manganese doping concentrations. X-ray diffraction pattern (XRD) of films showed the formation of tetragonal phase of SnO_2 and orthorhombic ZrSnO_4. Decrease in crystallinity with increase of Mn concentration was observed for the films. Scanning electron microscopy (SEM) showed the formation of grain growth with an increase in Mn concentration. X-ray photo electron spectroscopy (XPS) confirmed the presence of Zr"4"+, Sn"4"+ and Mn"2"+ ion in ZrO_2–SnO_2: Mn films. Vibrating sample magnetometer (VSM) measurements reveal the presence of magnetic properties in Mn doped nanocomposite thin films. Antiferromagnetic interactions were observed for 5 mol % Mn doping. An average transmittance >80% (UV - Vis region) was observed for all the films. Band gap of the films decreased from 4.78 to 4.41 eV with increase in Mn concentration. Photoluminescence (PL) spectra of the films exhibited emission peaks in visible region of the electromagnetic spectra. Conductivity of the film increased up to 3 mol % Mn doping and then decreased. - Highlights: • ZrO_2–SnO_2: Mn films were deposited onto quartz substrates by Sol –Gel dip coating. • Structural, magnetic, optical and electrical properties of the films were analyzed. • Optical band gap decreased with increase in manganese concentration. • Ferromagnetic behavior was observed for Mn doped films. • These ferromagnetic ZrO_2–SnO_2: Mn films find application in spintronic devices.

Surface modification of quartz fibres for dental composites through a sol-gel process.

Science.gov (United States)

Wang, Yazi; Wang, Renlin; Habib, Eric; Wang, Ruili; Zhang, Qinghong; Sun, Bin; Zhu, Meifang

2017-05-01

In this study, quartz fibres (QFs) surface modification using a sol-gel method was proposed and dental posts reinforced with modified QFs were produced. A silica sol (SS) was prepared using tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimethoxysilane (γ-MPS) as precursors. The amount of γ-MPS in the sol-gel system was varied from 0 to 24wt.% with a constant molar ratio of TEOS, ethanol, deionized water, and HCl. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and contact angle (CA) measurements were used to characterize the modified QFs, which confirmed that SS had successfully coated the surface of QFs. SEM images showed good interfacial bonding between the modified QFs and the resin matrix. The results of three-point bending tests of the fibre reinforced composite (FRC) posts showed that the QFs modified by SS with 12wt.% γ-MPS presented the best mechanical properties, demonstrating improvements of 108.3% and 89.6% for the flexural strength and flexural modulus, respectively, compared with untreated QFs. Furthermore, the sorption and solubility of the prepared dental posts were also studied by immersing the posts in artificial saliva (AS) for 4weeks, and yielded favourable results. This sol-gel surface modification method promises to resolve interfacial bonding issues of fibres with the resin matrix, and produce FRC posts with excellent properties. Copyright © 2017. Published by Elsevier B.V.

Evaluation of micro-abrasion-corrosion on SiO2-TiO2-ZrO2 coatings synthesized by the sol-gel method

Science.gov (United States)

Bautista Ruiz, J.; Aperador, W.; Caballero Gómez, J.

2016-02-01

The medical science and the engineering, work to improve the materials used in the manufacture of joint implants, since they have a direct impact on the quality of people life. The surgical interventions are increasing worldwide with a high probability of a second or even a third intervention. Around these circumstances, it was evaluated the behaviour against microabrasion-corrosion phenomena on SiO2 TiO2 ZrO2 coatings, synthesized by the sol-gel method with concentration of the Si/Ti/Zr precursors: 10/70/20 and 10/20/70. The coatings were deposited on AISI 316 LVM stainless steel substrates. The morphological characterization of the wear was made by AFM techniques. It was observed that the coatings with higher levels of titanium have a good response to the phenomena of microabrasion-corrosion.

Slow Release of Plant Volatiles Using Sol-Gel Dispensers.

Science.gov (United States)

Bian, L; Sun, X L; Cai, X M; Chen, Z M

2014-12-01

The black citrus aphid, also known as the tea aphid, (Toxoptera aurantii Boyer) attacks economically important crops, including tea (Camellia sinensis (L.) O. Kuntze). In the current study, silica sol-gel formulations were screened to find one that could carry and release C. sinensis plant volatiles to lure black citrus aphids in a greenhouse. The common plant volatile trans-2-hexen-1-al was used as a model molecule to screen for suitable sol-gel formulations. A zNose (Electronic Sensor Technology, Newbury Park, CA) transportable gas chromatograph was used to continuously monitor the volatile emissions. A sol-gel formulation containing tetramethyl orthosilicate and methyltrimethoxysilane in an 8:2 (vol:vol) ratio was selected to develop a slow-release dispenser. The half-life of trans-2-hexen-1-al in the sol-gel dispenser increased slightly with the volume of this compound in the dispenser. Ten different volatiles were tested in the sol-gel dispenser. Alcohols of 6-10 carbons had the longest half-lives (3.01-3.77 d), while esters of 6-12 carbons had the shortest (1.53-2.28 d). Release of these volatiles from the dispensers could not be detected by the zNose after 16 d (cis-3-hexenyl acetate) to 26 d (3,7-dimethylocta-1,6-dien-3-ol). In greenhouse experiments, trans-2-hexen-1-al and cis-3-hexen-1-ol released from the sol-gel dispensers attracted aphids for ≍17 d, and release of these volatiles could not be detected by the zNose after ≍24 d. The sol-gel dispensers performed adequately for the slow release of plant volatiles to trap aphids in the greenhouse. © 2014 Entomological Society of America.

Spectroellipsometric study of the sol-gel nanocrystalline ITO multilayer films

Energy Technology Data Exchange (ETDEWEB)

Stoica, T.F.; Gartner, M.; Losurdo, M.; Teodorescu, V.; Blanchin, M.; Stoica, T.; Zaharescu, M

2004-05-01

Tin-doped indium oxide (ITO) thin films have been deposited by sol-gel process using 'sols' of indium and tin isopropoxides. The thickness of one deposited ITO layer is approximately 50 nm. The desired thickness was obtained by 1-5 successive depositions. The XTEM cross-sectional view of an ITO sample with five depositions showed a clear delimitation of the layers with an alternating structure dense/porous ITO layers. The void fraction in porous regions varies between 20 and 25%. Cubic bixbyite In{sub 2}O{sub 3} nanocrystals with size of 10-20 nm and no phases separation of tin oxide were observed. The optical properties of the films have been investigated by optical transmission and spectroscopic ellipsometry. Reliable optical constants and porosity are obtained only with the model of internal structure based on XTEM results.

Production of continuous mullite fiber via sol-gel processing

Science.gov (United States)

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

1990-01-01

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

Incorporation of europium III complex into nanoparticles and films obtained by the Sol-Gel methodology

Directory of Open Access Journals (Sweden)

Faley Jean de Sousa

2010-03-01

Full Text Available The sol-gel process is very effective for the preparation of new materials with potential applications in optics, sensors, catalyst supports, coatings, and specialty inorganic polymers that can be used as hosts for the accommodation of organic molecules. The low temperature employed in the process is the main advantage of this methodology. In this work, the europium (III complex with 1,10-phenantroline was prepared, and this luminescent complex was incorporated into silica nanoparticles and films by the sol-gel process. The nanoparticles were obtained by the modified Stöber methodology. The films were obtained by the dip-coating technique, at different deposition rates and numbers of layers. The nanoparticles and films were characterized by photoluminescence, thermal analysis, and Raman and infrared spectroscopies. Characterization revealed that the europium (III complex was not affected upon incorporation into the nanoparticles and films, opening a new field for the application of these materials.

Ultrasound-assisted sol-gel synthesis of ZrO2.

Science.gov (United States)

Guel, Marlene Lariza Andrade; Jiménez, Lourdes Díaz; Hernández, Dora Alicia Cortés

2017-03-01

Synthesis of tetragonal ZrO 2 by both conventional sol-gel and ultrasound-assisted sol-gel methods and using a non-ionic surfactant Tween-20, was performed. A porous microstructure composed of nanometric particles was observed. Tetragonal ZrO 2 was obtained using a low heat treatment temperature of powders, 500°C by both methods. A higher crystallinity and a shorter reaction time were observed when ultrasound was used in the sol-gel method due to the cavitation phenomenon. Copyright © 2016 Elsevier B.V. All rights reserved.

Imprinted sol-gel electrochemical sensor for the determination of benzylpenicillin based on Fe3O4/SiO2 multi-walled carbon nanotubes-chitosans nanocomposite film modified carbon electrode

International Nuclear Information System (INIS)

Hu Yufang; Li Jiaxing; Zhang Zhaohui; Zhang Huabin; Luo Lijuan; Yao Shouzhuo

2011-01-01

Graphical abstract: A novel imprinted sol-gel electrochemical sensor based on Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposite film and a thin MIP film has been developed on a carbon electrode. Highlights: → A novel imprinted sol-gel electrochemical sensor based on Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposites has been developed. → Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposites act as 'electronic wires' to enhance the electron transfer. → The inherent specificity of the MIPs brings about highly selectivity. The imprinted sensor detects benzylpenicillin in real samples successfully. - Abstract: Herein, a novel imprinted sol-gel electrochemical sensor based on multi-walled carbon nanotubes (MWNTs) doped with chitosan film on a carbon electrode has been developed. Prior to doped, the MWNTs have been decorated with Fe 3 O 4 nanoparticles which have been coated uniformly with SiO 2 layer. The characterization of imprinted sensor has been carried out by X-ray diffraction and scanning electron microscopy. The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry and differential pulse voltammetry. The imprinted sensor offers a fast response and sensitive benzylpenicillin quantification. The fabricated benzylpenicillin imprinted sensor exhibits a linear response from 5.0 x 10 -8 to 1.0 x 10 -3 mol L -1 with a detection limit of 1.5 x 10 -9 mol L -1 . For samples analysis, perfect recoveries of the imprinted sensor for benzylpenicillin indicated that the imprinted sensor was able to detect benzylpenicillin in real samples successfully.

Cholesterol biosensor based on a plastic optical fibre with sol-gel: structural analysis and sensing properties

Science.gov (United States)

Razo-Medina, D. A.; Trejo-Durán, M.; Alvarado-Méndez, E.

2018-02-01

In this paper, we report the design and characterization of an optical fibre cholesterol biosensor by using sol-gel immobilization technique. The cholesterol enzyme is encapsulated inside of the sol-gel film onto an end of a plastic optical fibre. Two film deposition methods (Dip-Coating and Immersion) were studied. The morphology analysis and sensing properties permit us to determine the best film deposition to sense cholesterol concentration. The range of measured is 4.4-5.2 mM in real time and our results were validated by comparing them with other previously published results. The biosensor is portable, simple cheap, and easy to use.

Sol-Gel Chemistry for Carbon Dots.

Science.gov (United States)

Malfatti, Luca; Innocenzi, Plinio

2018-03-14

Carbon dots are an emerging class of carbon-based nanostructures produced by low-cost raw materials which exhibit a widely-tunable photoluminescence and a high quantum yield. The potential of these nanomaterials as a substitute of semiconductor quantum dots in optoelectronics and biomedicine is very high, however they need a customized chemistry to be integrated in host-guest systems or functionalized in core-shell structures. This review is focused on recent advances of the sol-gel chemistry applied to the C-dots technology. The surface modification, the fine tailoring of the chemical composition and the embedding into a complex nanostructured material are the main targets of combining sol-gel processing with C-dots chemistry. In addition, the synergistic effect of the sol-gel precursor combined with the C-dots contribute to modify the intrinsic chemo-physical properties of the dots, empowering the emission efficiency or enabling the tuning of the photoluminescence over a wide range of the visible spectrum. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes

Directory of Open Access Journals (Sweden)

Shiraz Labib

2013-12-01

Full Text Available Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.

Feasibility study on the sol-gel deposition of nanostructured materials based on oxides and fluorides for coatings on solar collector glazing

Energy Technology Data Exchange (ETDEWEB)

Schueler, A.; Chambrier, E. De

2005-10-15

This illustrated annual report reviews work done at the Federal Institute of Technology (EPFL) in Lausanne, Switzerland, on the architectural integration of thermal solar collectors into buildings. This is often limited by their black colour and the visibility of the tubes and corrugations of the absorber sheets. Although a certain freedom in the choice of colour would be desirable, the coloured appearance should not cause excessive performance degradation. Multi-layered thin film interference filters on the collector glazing can produce a coloured reflection while transmitting the non-reflected radiation entirely to the absorber. The paper describes suitable optical interference filters which have been designed and optimised by numerical simulation and that will be manufactured by the sol-gel dip-coating process. Light scattering has to be avoided, which implies a need for particle sizes much smaller than the wavelengths of the incoming light. The paper proposes that corresponding thin films should therefore consist of nano-structured materials. The sol-gel deposition of all proposed materials has been demonstrated successfully. The paper presents the results of the work using various materials including titanium-silicon mixed oxides, gold-silicon dioxide, porous silicon dioxide, magnesium fluoride and quaternary films.

Epoxy-based organic-inorganic nanocomposite coatings and films prepared by sol-gel process

Czech Academy of Sciences Publication Activity Database

Špírková, Milena; Brus, Jiří; Matějka, Libor

2004-01-01

Roč. 6, 3-4 (2004), s. 7-15 R&D Projects: GA ČR GA203/01/0735; GA AV ČR IAA4050008; GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : sol-gel process * nanocomposite s * solid-state NMR Subject RIV: CD - Macromolecular Chemistry

Silica doped with lanthanum sol–gel thin films for corrosion protection

International Nuclear Information System (INIS)

Abuín, M.; Serrano, A.; Llopis, J.; García, M.A.; Carmona, N.

2012-01-01

We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: ► Silica sol–gel films doped with lanthanum ions were synthesized. ► Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. ► La-acetate is an affordable chemical reactive preferred for the industry. ► Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. ► An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

Photoluminescence analysis of Ce3+:Zn2SiO4 & Li++ Ce3+:Zn2SiO4: phosphors by a sol-gel method

Science.gov (United States)

Babu, B. Chandra; Vandana, C. Sai; Guravamma, J.; Rudramadevi, B. Hemalatha; Buddhudu, S.

2015-06-01

Here, we report on the development and photoluminescence analysis of Zn2SiO4, Ce3+:Zn2SiO4 & Li+ + Ce3+: Zn2SiO4 novel powder phosphors prepared by a sol-gel technique. The total amount of Ce3+ ions was kept constant in this experiment at 0.05 mol% total doping. The excitation and emission spectra of undoped (Zn2SiO4) and Ce3+ doped Zn2SiO4 and 0.05 mol% Li+ co-doped samples have been investigated. Cerium doped Zn2SiO4 powder phosphors had broad blue emission corresponding to the 2D3/2→2FJ transition at 443nm. Stable green-yellow-red emission has been observed from Zn2SiO4 host matrix and also we have been observed the enhanced luminescence of Li+ co-doped Zn2SiO4:Ce3+. Excitation and emission spectra of these blue luminescent phosphors have been analyzed in evaluating their potential as luminescent screen coating phosphors.

Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell

Directory of Open Access Journals (Sweden)

Yan-Huei Lee

2016-11-01

Full Text Available The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 °C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 °C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy-benzo(1,2-b:4,5-b’dithiophene-2,6-diyl-alt- (4-(2-ethylhexanoyl-thieno [3,4-b]thiophene--2-6-diyl] (PBDTTT-C-T and [6,6]-Phenyl C71 butyric acid methyl ester ([70]PCBM as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors.

The development and characterization of sol-gel substrates for chemical and optical applications

Science.gov (United States)

Powers, Kevin William

1998-12-01

The sol gel process can be used to make monolithic porous glass for various scientific and engineering uses. The porosity of the material imparts a large surface area which is advantageous in applications such as catalyst supports or in the study of surface mediated chemical reactions. The chemical stability and transparency of the porous glass also make it suitable for use in the emerging field of optical sensors. In this study fluoride catalysis is used to produce sol gel monoliths with pore radii of up to 400 Angstroms, four times larger than any previously reported using conventional drying techniques. Gel monoliths with pore radii of 200 Angstroms were found to have the best combination of surface area, pore volume and optical transparency. Typical monoliths have surface areas of 150 m2/g and pore volumes of 1.60 cm3/g with good transparency. The monoliths are chemically stable, have good mechanical strength and can be easily rehydrated without cracking. The substrates are also suitable for sintering into dense high purity silica glass with little tendency towards foaming. An in-depth study of the catalytic effect of fluoride on the sol gel process is also included. It has been theorized that fluoride serves to expand the coordination sphere of the silicon center making it more subject to nucleophilic attack. In this work an ion-specific fluoride electrode is used to monitor free fluoride concentrations in HF catalyzed sols while silicic acid is added in the form of tetramethoxysilane (TMOS). It is found that fluoride is rapidly bound by the silicic acid in a ratio of four to one, indicating the formation of silicon tetrafluoride. A concurrent decrease in pH suggests that a pentacoordinate species is formed that is more stable than previously thought. A polymerization mechanism is proposed that explains the hydrophobicity of fluoride catalyzed gels and the difficulty in retaining structural fluoride in fluoride catalyzed sol gel glasses. Finally, several

Variation in Structural and Optical Properties of Al Doped ZnO Nanoparticles Synthesized by Sol-gel Process

Directory of Open Access Journals (Sweden)

Vanaja Aravapalli

2017-04-01

Full Text Available This article focuses on analyzing structural and optical properties of Al doped ZnO (AZO synthesized with two different precursors aluminum chloride and aluminum nitrate. The nanoparticles were successfully fabricated and characterized at room temperature by sol-gel process. The objective of improving properties of ZnO nanoparticles by introducing dopants was successful with formation of nanoparticles having different crystalline sizes, optical absorption and luminescence properties. The two different sources influenced properties of ZnO. The particles with less crystalline size obtained from aluminum nitrate. Change in morphology from spherical to bar like morphology proved from SEM spectra. Presence of functional groups predicted from FTIR spectra. PL spectra proved UV emission and visible emission for AZO nanoparticles synthesized using dopant sources aluminum chloride and aluminum nitrate respectively. The obtained properties prove successful utilization of AZO nanoparticles as building materials in fabrication of optoelectronic devices.

Effects of parameters of sol-gel process on the phase evolution of sol-gel-derived hydroxyapatite

International Nuclear Information System (INIS)

Eshtiagh-Hosseini, Hossein; Housaindokht, Mohammad Reza; Chahkandi, Mohammad

2007-01-01

It has been established that hydroxyapatite powders can be produced using an alkoxide-based sol-gel technique. Nanocrystalline powders of hydroxyapatite (HA) were prepared from Ca(NO 3 ) 2 .4H 2 O and PO(OC 2 H 5 ) 3 as calcium and phosphorus precursors, respectively, using a sol-gel route. For a number of samples, sol of phosphorus was first hydrolyzed for 24 h with distilled water. The sol temperature, aging time and heat treatment temperature on apatite formation were systematically studied. Increasing the aging time affected the reducing of CaO. Also, increasing the mixed sol solution temperature up to 80 deg. C had a positive effect on the disappearance of impurity phases. With the increase of the calcination temperature >600 deg. C, calcium phosphate impurity phases disappeared. Structural evolution during the synthesis of hydroxyapatite is investigated by using infrared (IR) analysis, X-ray diffraction (XRD), thermal behavior (DTA), and elemental analysis of electron microscopy examination (SEM). X-ray diffraction with the aid of Scherrer and Williamson-Hall equations has been used to characterize the distributions of crystallite size and micro-strain of HA powders .The results indicated that mean crystallite size increased and micro-strain decreased significantly with the rise in firing temperature

INKJET PRINTING OF ALUMOOXIDE SOL FOR DEPOSITION OF ANTIREFLECTING COATINGS

Directory of Open Access Journals (Sweden)

E. A. Eremeeva

2017-01-01

Full Text Available Subject of Research. This work describes for the first time the formation of antireflective coating on the base of boehmite phase of AlOOH with low refractive index (1.35 by inkjet printing on the nonporous substrate. This method gives the possibility to increase the contrast of colorful interfering images by 32% obtaining by inkjet printing of titanium dioxide sol. The usage of this technology enables to obtain patterns with wide viewing angle and makes them highly stable. Methods. Traditional sol-gel method with peptizing agents and heating for 90oC was applied for sol synthesis. Then the mixture was under sonic treatment for the obtaining of viscous sol. The viscosity was determined by Brookfield HA/HB viscometer, and the surface tension by Kyowa DY-700 tensiometer. Aluminum oxide ink was deposited on polished slides (26×76 mm2, Paul Marienfeld, Germany, over titanium oxide layer. To print titania ink, we use a desktop office printer Canon Pixma IP 2840 and Dimatix DMP-2831. The thickness of an inkjet AlOOH layer after drying in the air and removal of the solvents did not exceed 150 nm with an RI not less than 1.35 in the entire visible range. Results. The stable colloidal ink was obtained for the first time on the base of aluminum oxide matrix with neutral pH. The rheology was regulated by controlling parameters of sol-gel method in the system of aqueous titanium dioxide sol and by adding ethanol that affects the charge of double electrical layer of disperse phase. The controllable coalesce of drops enables to apply antireflection coating within the thickness accuracy of 10 nm. The morphology of particles and the topology of printed structures were analyzed by optical, scanning electron and atomic-force microscopes. Practical Relevance. We have proposed the approach to obtain colorful, interference patterns using two types of high refractive inks with different refractive indexes. The inkjet printing method opens new opportunities for

Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials

Science.gov (United States)

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

2004-01-01

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

Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

Energy Technology Data Exchange (ETDEWEB)

Luna, F Perdomo; Atik, M; Avaca, Luis A; Aegerter, M A [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica

1996-12-31

Zr O{sub 2} thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C{sub 3} H{sub 7})4/C{sub 3} H{sub 7} OH = 0.5), glacial acetic acid and water (C H{sub 3} CO OH/H{sub 2} O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 {mu}m. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H{sub 2} SO{sub 4} at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7 16 refs., 3 figs., 1 tab.

Polarization fatigue resistance of Ca-doped Pb(Zr0.52Ti0.48)O3 thin films prepared by the sol-gel method

International Nuclear Information System (INIS)

Wei, T.; Wang, Y.; Zhu, C.; Dong, X.W.; Xia, Y.D.; Zhu, J.S.; Liu, J.-M.

2008-01-01

The ferroelectric and polarization fatigue characteristics of Pb 1-x Ca x (Zr 0.52 Ti 0.48 )O 3 (PCZT) thin films prepared using the sol-gel method were studied. The Ca-doping slightly suppresses the ferroelectricity of Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) because of the quantum paraelectric behavior of CaTiO 3 . Compared with PZT thin films, the PCZT (x=0.2) thin films show enhanced fatigue resistance at room temperature, further emphasized by the almost fatigue-free behavior at 100 K. The temperature-dependent dc-conductivity suggests a decrease of the oxygen vacancy density by almost 20 times and a slightly declined activation energy U for oxygen vacancies, upon increasing of the Ca-doping content from 0.0 to 0.2. It is argued that the improved fatigue endurance is ascribed to the decreasing density of oxygen vacancies due to the Ca-doping, although the lowered activation energy of oxygen vacancies is unfavorable. (orig.)

Detection of volatile organic compounds using an optical fiber sensor coated with a sol-gel silica layer containing immobilized Nile red

Science.gov (United States)

Liu, Dejun; Lian, Xiaokang; Mallik, Arun Kumar; Han, Wei; Wei, Fangfang; Yuan, Jinhui; Yu, Chongxiu; Farrell, Gerald; Semenova, Yuliya; Wu, Qiang