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Sample records for sol-gel technique corporate

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

    Science.gov (United States)

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

    2009-05-29

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

  2. 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.

  3. A modified sol-gel technique for pore size control in porous aluminum oxide nanowire templates.

    Science.gov (United States)

    Kelly, Daniel N; Wakabayashi, Ryo H; Stacy, Angelica M

    2014-11-26

    A modified sol-gel technique was developed to continuously vary the pore diameters in porous alumina templates for the purpose of growing nanowires. To coat the pore walls, the porous alumina film is initially soaked in a methanol/water solution to fill the pores with the desired concentration of water. The porous alumina film is then exposed to a solution of 3-aminopropyltriethoxysilane (APTES) in toluene, creating a surface layer of APTES. The concentration of water in the pores correlates with the thickness of the APTES polymer coating that is obtained. This approach exerts greater control over the extent of silane polymerization than traditional sol-gel reactions by limiting the amount of water present for reaction. Factors such as the APTES concentration, exposure time, and organic cosolvent choice did not influence the coating thickness. However, the density and thickness of the APTES coating can be manipulated by varying the pH of the methanol/water solution as well as post-treatment annealing. Further modification of the pore size was achieved by subsequent reaction of the APTES coating with poly(methyl methacrylate) (PMMA). The PMMA couples to amine groups on the APTES polymer surface by an aminolysis reaction. Bismuth telluride nanowires were electrodeposited in the polymer-coated porous alumina templates using previously established methods. Nanowire diameters were smaller when the nanowires were prepared in modified templates as anticipated.

  4. Surfactant-less Sol-Gel Technique for the Synthesis of Mg-ZnO Nanoparticle

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    Kadhim Wafaa A.

    2017-01-01

    Full Text Available In this study, sol–gel technique has been used to prepare nanoparticle Mg doped ZnO with 2 wt. % at low pH without using any capping or surfactant agent. The Mg-ZnO nanostructure, surface area and porosity, surface morphology and element analysis was analyzed by X-Ray Diffraction (XRD, Fourier Transforms Infra-Red (FTIR, N2 Physisorption and Field Emission Scanning Electron Microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX. The characterizations confirmed that the surfactant is not necessary for sol-gel synthesis technique, whereby highly crystalline material with smaller crystallite size (30nm and high surface area (21.7 was obtained. Besides, the synthesis approach is useful for accurately immobilized the required amount of Mg as doping element on ZnO material with the accuracy up to 99.5% confirmed through EDX analysis.

  5. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

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    M.I. Khan

    Full Text Available In this work, zinc oxide (ZnO multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV–Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications. Keywords: Multilayer films, Semiconductor, ZnO, XRD, SEM, Optoelectronic properties

  6. Nanostructured TiO2 thin films for DSSCs prepared by sol gel technique

    Science.gov (United States)

    Bakar, Siti Noraini Abu; Abdullah, Huda; Mahbor, Kamisah Mohamad

    2017-07-01

    In this research, nanostructured TiO2 thin films were prepared by sol-gel technique for dye-sensitized solar cells (DSSCs) were investigated. The nanostructured thin films were prepared using commercial Titania powder (Degussa P25) and titanium (IV) ethoxide (TEOT). The resulting solution were spin-coated on pieces of indium-doped tin oxide (InO2:Sn, ITO) transparent glass (8 Ω/sq, TEC GlassTM) with an area of 10 × 10 mm2 at a rate of 2000 rpm for 30 seconds. The films were annealed in furnace at 450 °C for 60 min. The working electrode was then immersed in the solution of N-719 (Ruthenium) dye at room temperature for 24 h. A thin film of platinum (Pt) was deposited on the ITO-glass substrate as the counter electrode using print-screen technique. The structures, morphological and optical properties of the films, were examined using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and UV-VIS spectrometer respectively. The XRD results showed that the crystalline phase of the film was anatase. The micrograph obtained using FESEM demonstrated that the prepared TiO2 film has a nanosructured characteristic. The photovoltaic properties of DSSC was studied under an incident irradiation of 100 mW/cm2. The energy conversion efficiency (η) of the DSSC with nanostuctured TiO2 (P25) and TiO2 was 0.3% and 0.2 % respectively.

  7. Synthesis and Thermal Characterization of Hydroxyapatite Powders Obtained by Sol-Gel Technique

    Science.gov (United States)

    Jiménez-Flores, Y.; Camacho, N.; Rojas-Trigos, J. B.; Suárez, M.

    The development of bioactive materials presents an interesting and an extremely relevant problem to solve, in the development of customized cranial and maxillofacial prosthesis, bioactive coating, and cements, for example. In such areas, one of the more employed materials is the synthetic hydroxyapatite, due to its proved biocompatibility with the human body; however, there are few studies about the thermal affinity with the biological surroundings, and most of them are centered in the thermal stability of the hydroxyapatite instead of its transient thermal response. In the present paper, the synthesis and physical-chemical characterization of hydroxyapatite samples, obtained by the sol-gel technique employing ultrasonic mixing, are reported. Employing X-ray diffraction patterns, XEDS and FTIR spectra, the crystal symmetry, chemical elements, and the present functional groups of the studied samples were determined and found to correspond to those reported in the literature, with a stoichiometry close to the ideal for biological applications. Additionally, by means of the photoacoustic detection and infrared photothermal radiometry (IPTR) techniques, the thermal response of the samples was obtained. Analyzing the photoacoustic data, the synthetized samples show photoacoustic opaqueness, responding in the thermally thick regime in the measurement range, and their thermal effusivity was also determined, having values of 1.47 folds the thermal effusivity of the mandibular human bone. Finally, from the IPTR measurements, the thermal diffusivity and thermal conductivity of the samples were also determined, having good agreement with the reported values for synthetic hydroxyapatite. The structural and thermophysical properties of the here reported samples show that the synthesized samples have good thermal affinity with the mandibular human bone tissue, and are suitable for biomedical applications.

  8. 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

    National Research Council Canada - National Science Library

    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...

  9. Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique

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    Nicolás Díaz Silva

    2017-01-01

    Full Text Available Carbon nanohybrid material (CNF/γ-Fe2O3 was obtained via a modified sol-gel technique consisting of two steps: functionalization of carbon nanofibers (CNF in H2SO4/HNO3 followed by synthesis using Fe(NO33∙9H2O. As a result, the iron content of the CNF/γ-Fe2O3 was increased by more than twice from about 40% to about 87% mass percent, compared to the pristine CNF and oxidized CNF specimens, as proved by energy dispersive X-ray fluorescence. Scanning electron microscopy images exhibited “cumulus” on the CNF/γ-Fe2O3 specimen surface, which showed the highest iron mass percentage, proved by energy dispersive X-ray spectroscopy. Transmission electron microscopy images confirmed attachment of γ-Fe2O3 cumulus to the inner and outer surfaces of the CNF walls after synthesis. The characteristic peaks of Fe 2p3/2 and Fe 2p1/2 appeared in the XPS spectra obtained on CNF/γ-Fe2O3. In addition, X-ray diffraction (XRD results indicated formation of γ-Fe2O3 during the synthesis process. The Raman spectrum of the CNF/γ-Fe2O3 sample displays peaks with positions close to characteristic peaks of highly crystalline and monodisperse maghemite nanocrystallites. The synthesis of CNF/γ-Fe2O3 leads to an increase in the hydrophilicity of CNF and magnetic properties at room temperature.

  10. TiO2/PCL hybrid materials synthesized via sol-gel technique for biomedical applications.

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    Catauro, M; Bollino, F; Papale, F; Marciano, S; Pacifico, S

    2015-02-01

    The aim of the present work has been the synthesis of organic/inorganic hybrid materials based on titanium dioxide and poly(ε-caprolactone) (PCL) to be used in the biomedical field. Several materials have been synthesized using sol-gel methods by adding different amounts of polymer to the inorganic sol. The obtained gels have been characterized using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The FT-IR data allowed us to hypothesize that the structure formed was that of an interpenetrating network, realized by hydrogen bonds between TiOH groups in the sol-gel intermediate species and carbonyl groups in the polymer repeating units. SEM and AFM analyses highlighted that the obtained materials were nanostructurated hybrids. To evaluate the biological properties of the hybrids, their bioactivity and cytotoxicity were investigated as a function of the PCL amount. The bioactivity of the synthesized systems was proven by the formation of a hydroxyapatite layer on the surface of samples soaked in a fluid simulating human blood plasma (SBF). MTT cytotoxicity tests and Trypan Blue dye exclusion tests were carried out exposing NIH-3T3 mouse embryonic fibroblasts for 24 and 48h to extracts from the investigated hybrid materials. The results showed that all the hybrids had a non-cytotoxic effect on target cells. Copyright © 2014. Published by Elsevier B.V.

  11. Development of flame retardant cotton fabric based on ionic liquids via sol-gel technique.

    Science.gov (United States)

    Bentis, A.; Boukhriss, A.; Boyer, D.; Gmouh, S.

    2017-10-01

    In this study, flame retardant cotton fabrics were developed by the sol-gel method, in order to enhance their flame retardant proprieties. For this aim, seven sols were prepared using tetraethylorthosilicate (TEOS) and different ionic liquids (ILs) consist on pyridinium and Methylimidazolium cations with different anions such as: PF6‑, CH3COO‑, and Br‑. Those sols were applied separately to the cotton fabrics by a pad-dry-cure process. The flame retardant properties of functionalized cotton fabrics before and after washing were determined by the vertical flame tests according to ISO6940:2004(F) standard. The effects of anions have been thoroughly investigated, aiming at the optimization of the targeted properties. Thermogravimetric and mechanical according to NF EN ISO 13934-1:2013standard, analyses have been also investigated. The results showed that flame retardancy, thermal stability and mechanical properties of treated fabrics were enhanced by using ionic liquids.

  12. Sensing CO gas with SnO{sub 2} thin films wetted with Cu prepared by sol-gel technique

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    Tirado G, S.; Cazares R, J. M. [Escuela Superior de Fisica y Matematicas, IPN, A. P. 75-544, 07300 Mexico D. F. (Mexico); Maldonado, A. [Departamento de Ingenieria Electrica, Centro de Investigacion y de Estudios Avanzados, IPN, A. P. 14-740, 07000 Mexico D. F. (Mexico)

    2009-10-15

    Pure and Cu surface deposited SnO{sub 2} thin films have been prepared on soda-lime substrate using the sol-gel technique. The sensing CO gas properties were investigated in 230 nm in thickness thin films. Pure thin films were wetted with several layers of Cu. The sensors were fabricated and proved at 0, 1, 5, 50, 100 and 200 ppm concentration CO gas and at 23, 100, 200 and 300 C working temperatures. The structural, morphology, electrical and optical properties of such thin films are reported. The route of 2-methoxyethanol and monoethanolamine was used. The resistance was high for all the samples. As was proposed, all the samples resulted enough amorphous and so the X-ray diffraction spectra show such structural state. the surface morphology for the samples was characterized by SEM and also by AFM techniques. (Author)

  13. Antimicrobial activity of hemocompatible silver doped hydroxyapatite nanoparticles synthesized by modified sol-gel technique

    Science.gov (United States)

    Jadalannagari, Sushma; Deshmukh, Ketaki; Ramanan, Sutapa Roy; Kowshik, Meenal

    2013-02-01

    Silver doped hydroxyapatite (Ag x Ca100-x (PO4)6 (OH)2) nanorods were synthesized using a modified sol gel method at a low temperature of 100 °C. Silver concentration was varied as x = 1, 3 and 5. X-ray diffraction studies showed that the synthesized silver doped hydroxyapatite (Ag-HAp) was fully crystalline with hexagonal structure and an average crystallite size of 25 nm. At all the doping concentrations, the nanoparticles were rod shaped with an average length of 110-180 nm and diameter of 20-25 nm as determined from transmission electron microscopy (TEM) studies. These compounds were tested for their antimicrobial activities against E. coli (MTCC 2345) and S. aureus (MTCC 737). Antimicrobial activity was observed for all the three silver doping concentrations with the highest activity for x = 3, in terms of the zone of inhibition and the percentage reduction in the number of colonies. Hemolysis ratios for x = 1 and 3 Ag-HAp samples were below 2 %, indicating that they are highly hemocompatible and can be a promising biomaterial for tissue engineering applications in orthopedics.

  14. Synthesis and magnetic properties of barium-calcium hexaferrite particles prepared by sol-gel and microemulsion techniques

    Science.gov (United States)

    Jotania, R. B.; Khomane, R. B.; Chauhan, C. C.; Menon, S. K.; Kulkarni, B. D.

    The preparation of W-type hexaferrite particles with the composition BaCa 2Fe 16O 27 by microemulsion and a stearic acid sol-gel method with and without surfactant has been investigated at various sintering temperatures. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) and Fourier transform infrared (FTIR) techniques. The effect of sintering temperature on the properties of BaCa 2Fe 16O 27 hexaferrites has been studied. The value of saturation magnetization ( Ms) depends on types of surfactant used. The sample prepared in the presence of polyoxyethylene (20) sorbitan monooleat (Tween 80) shows low saturation magnetization ( Ms=15.10 emu/g), whereas the other sample prepared in the presence of a surfactant cetyltrimethylammonium bromide (CTAB) exhibits high saturation magnetization ( Ms=24.60 emu/g) compared to the normal sample.

  15. On the synthesis of nickel oxide nanoparticles by sol-gel technique and its electrocatalytic oxidation of glucose

    Science.gov (United States)

    Danial, Amgad S.; Saleh, M. M.; Salih, S. A.; Awad, M. I.

    2015-10-01

    Nickel oxide nanoparticles (nano-NiOx) of peculiar shape are prepared by sol-gel technique and its electrocatalytic activity is evaluated at different conditions. The thus prepared nanoparticles are annealed at three different temperatures, i.e., 200, 400 and 600 °C and anchored on glassy carbon (GC) electrode. Nano-NiOx modified GG (nano-NiOx/GC) electrodes are subjected to surface analysis techniques such as field emission scanning electron microscopy (FE-SEM) high resolution transmission electron micrograph (TEM) and X-ray diffraction (XRD). Electrochemical characterizations are performed using cyclic voltammetry and chronoamperometric techniques. The effects of annealing temperature on the morphological structure, surface concentration and subsequently on the electrochemical properties of nano-NiOx/GC are examined. Experimental results indicate that the grain size and electrochemical characteristics of the nano-NiOx/GC are significantly affected by the annealing temperature. The electrocatalytic oxidation of glucose at nano-NiOx/GC electrode is significantly enhanced especially with nano-NiOx annealed at 200 °C compared to those annealed at 400 and 600 °C. Nano-NiOx is believed to play a crucial role as a catalytic mediator to facilitate the charge transfer during the oxidation of glucose.

  16. The Variation of Optical Band Gap for ZnO:In Films Prepared by Sol-Gel Technique

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    Guomei Tang

    2013-01-01

    Full Text Available ZnO:In films with different concentrations (0–5 at.% are successfully synthesized on quartz substrates using sol-gel technique. The structure, morphology, and optical properties of ZnO:In films are investigated by X-ray diffraction, atomic force microscopy, and UV-visible spectrophotometer. It is found that all the films with columnar structural morphology grow along the preferred [001] orientation and the incorporation of indium can improve the crystallinity of ZnO films. The transmittance of the films is about 80% in the visible range. A change of the optical absorption edge from blue shift to red shift is observed for ZnO:In films as the doping concentration increases, which means that the optical band gap first increases and then decreases. The blue shift is due to the Burstein-Moss effect. The sharp jump of the absorption edge from blue-shift to red shift is ascribe to the band gap narrowing caused by the merging of the donor and conduction bands of ZnO:In at high doping concentration.

  17. Synthesis and magnetic properties of barium-calcium hexaferrite particles prepared by sol-gel and microemulsion techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jotania, R.B. [Department of Physics, Gujarat University, Ahmedabad 380 009, Gujarat (India)], E-mail: rbjotania@gmail.com; Khomane, R.B. [Chemical Engineering Division, National Chemical Laboratory, Pune 411008, Maharastra (India); Chauhan, C.C. [Department of Physics, Gujarat University, Ahmedabad 380 009, Gujarat (India); Menon, S.K. [Department of Chemistry, Gujarat University, Ahmedabad 380 009, Gujarat (India); Kulkarni, B.D. [Chemical Engineering Division, National Chemical Laboratory, Pune 411008, Maharastra (India)

    2008-03-15

    The preparation of W-type hexaferrite particles with the composition BaCa{sub 2}Fe{sub 16}O{sub 27} by microemulsion and a stearic acid sol-gel method with and without surfactant has been investigated at various sintering temperatures. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) and Fourier transform infrared (FTIR) techniques. The effect of sintering temperature on the properties of BaCa{sub 2}Fe{sub 16}O{sub 27} hexaferrites has been studied. The value of saturation magnetization (M{sub s}) depends on types of surfactant used. The sample prepared in the presence of polyoxyethylene (20) sorbitan monooleat (Tween 80) shows low saturation magnetization (M{sub s}=15.10 emu/g), whereas the other sample prepared in the presence of a surfactant cetyltrimethylammonium bromide (CTAB) exhibits high saturation magnetization (M{sub s}=24.60 emu/g) compared to the normal sample.

  18. Electrical Investigation of Nanostructured Fe2O3/p-Si Heterojunction Diode Fabricated Using the Sol-Gel Technique

    Science.gov (United States)

    Mansour, Shehab A.; Ibrahim, Mervat M.

    2017-11-01

    Iron oxide (α-Fe2O3) nanocrystals have been synthesized via the sol-gel technique. The structural and morphological features of these nanocrystals were studied using x-ray diffraction, Fourier transform-infrared spectroscopy and transmission electron microscopy. Colloidal solution of synthesized α-Fe2O3 (hematite) was spin-coated onto a single-crystal p-type silicon (p-Si) wafer to fabricate a heterojunction diode with Mansourconfiguration Ag/Fe2O3/p-Si/Al. This diode was electrically characterized at room temperature using current-voltage (I-V) characteristics in the voltage range from -9 V to +9 V. The fabricated diode showed a good rectification behavior with a rectification factor 1.115 × 102 at 6 V. The junction parameters such as ideality factor, barrier height, series resistance and shunt resistance are determined using conventional I-V characteristics. For low forward voltage, the conduction mechanism is dominated by the defect-assisted tunneling process with conventional electron-hole recombination. However, at higher voltage, I-V ohmic and space charge-limited current conduction was became less effective with the contribution of the trapped-charge-limited current at the highest voltage range.

  19. Micro Structural, Optical and Magnetic Properties of Co-SiO2 Nanocomposite Synthesized by Sol-Gel Technique

    Science.gov (United States)

    Saha, Mrinal; Mukherjee, Soumya; Gayen, Arup; Mukherjee, Siddhartha

    2017-04-01

    Co-SiO2 nano composite has been synthesized via sol-gel technique using dextrose [C6H12O6] as a reducer and tetraethyl orthosilicate [Si(OCH2CH3)4] as oxide forming agent, respectively. The dried gel has been subsequently calcined at different temperature (850 and 900 °C) for 30 min in an inert atmosphere by N2 purging. The synthesized materials have been characterized by X-ray diffraction, high resolution transmission microscope, Fourier transform infrared spectroscopy, UV-Vis spectroscopy, scanning electron microscope, field emission microscope, atomic force microscope and physical property measurement system. The crystallite sizes of the face centered cubic cobalt nano composite materials have been found to be in the range of 14-28 nm. The crystallite size of the material found to be increased at higher calcination temperature due to the grain growth. The surface morphology of the obtained material has been found to be agglomerated but spherical in nature. This agglomeration tendency could be attributed to magnetic interaction between particles, large surface area as well as high surface energy. The band gap value of the obtained material has been determined to be 1.92 eV. The saturation magnetization (Ms) and the coercivity (Hc) of the composite material were found to be 29.45 emu g-1and 23.2 Oe, respectively. This technique has thus been found to be a convenient and effective method to prepare pure metallic cobalt nanoparticles with uniform size and homogeneous distribution throughout the matrix.

  20. Development of cobalt ferrite powder preparation employing the sol-gel technique and its structural characterisation

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    Olabi A.G.

    2010-06-01

    Full Text Available This work focuses on the development of a method to make nano cobalt ferrite powder using a solgel process. A particular emphasis is devoted to the understanding of the role of the chemical parameters involved in the solgel technique, and of the heat treatment on the structures and morphologies of the materials obtained. Several samples of cobalt ferrite powder were obtained by varying the initial parameters of the process in addition to the heat treatment temperature. Xray diffraction and scanning electron microscopy were used to identify the structure and morphology of samples demonstrating the influence of the initial parameters. DTA/TGA was carried out on one sample to identify important reaction temperatures during the heat treatment. The average particle size, as estimated for one sample by the full width at half maximum (FWHM of the strongest Xray diffraction (XRD peak, was found to be about 45 nm. It has been found that the chelating agent and the crosslinker have a critical influence on the resultant structure, the particle size and the particle size distribution.

  1. Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

    Energy Technology Data Exchange (ETDEWEB)

    Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.; Khairnar, R. S. [Thin Films and Devices Laboratory, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded – 431606 (India); Phatangare, A. B.; Dahiwale, S. S. [Department of Physics, Savitribai Phule Pune University, Pune – 411007 (India)

    2016-05-06

    We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

  2. Fluorescence technique for studying the sol-gel transition in the free-radical crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate

    Science.gov (United States)

    Pekcan, Oe.; Ylmaz, Y.; Okay, O.

    1994-11-01

    The steady-state fluorescence technique was used to study the free-radical crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate in the absence and presence of toluene at 75 C. A sol-gel phase transition was observed and monitored by an excited aromatic molecule during the gelation of the above system. Bond percolation theory was employed to quantify the results. The critical exponent and gel point were found to be around 0.45 and 0.36 both in bulk and solution polymerization.

  3. Fluorescence Technique for Studying the Sol--Gel Transition in the Free--Radical Crosslinking Copolymerization of Methyl Methacrylate and Ethylene Glycol Dimethacrylate

    Science.gov (United States)

    Pekcan, Önder; Yilmaz, Yalçýn; Okay, Oðuz

    1996-01-01

    The steady--state fluorescence technique was used to study the free--radical crosslinking copolymerization [1] of methyl methacrylate and ethylene glycol dimethacrylate in the absence and presence of toluene at 74°C. A sol--gel phase transition was observed and monitored by an excited aromatic molecule during the gelation of the above system. Bond percolation theory was employed to qualify the results [2,3]. The critical exponent and gel point were found to be 0.45 and 0.36 both in bulk and solution polymerization [4].

  4. Nanocrystal/sol-gel nanocomposites

    Science.gov (United States)

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

    2012-06-12

    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

  5. Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass

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    Mojtaba Nasr-Esfahani

    2008-01-01

    Full Text Available New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC porous, TiO2/Ag films were obtained after calcining at a temperature of 500°C. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methyl orange (MO under UV irradiation. After 500°C calcination, the microstructure of MC-TiO2 film without Ag addition exhibited a microstructure, while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Nanostructure anatase-phase TiO2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO2 deposited with 5×10−4 mol Ag exhibited the best photocatalytic efficiency, where 69% methyl orange can be decomposed after UV exposure for 1 hour.

  6. Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

    Science.gov (United States)

    Nimbalkar, Amol R.; Patil, Maruti G.

    2017-12-01

    In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

  7. 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)

  8. 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.

  9. Characterizations of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives for the Photoelectrochemical Solar Cell

    Directory of Open Access Journals (Sweden)

    D. S. C. Halin

    2014-01-01

    Full Text Available Cuprous oxide (Cu2O thin films were deposited onto indium tin oxide (ITO coated glass substrate by sol-gel spin coating technique using different additives, namely, polyethylene glycol and ethylene glycol. It was found that the organic additives added had a significant influence on the formation of Cu2O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and ultraviolet-visible spectroscopy (UV-Vis. Based on the FESEM micrographs, the grain size of film prepared using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC.

  10. Synthesis, Characterization and Catalytic Performance of H3SiW12O40/SiO2 Prepared by Sol-Gel Technique

    Directory of Open Access Journals (Sweden)

    W. N. R. W. Isahak

    2011-01-01

    Full Text Available The purpose of this work is to study the synthesis, characterization, and catalytic performance of two types of solid heteropoly acid catalysts, namely, silicotungstic acid bulk (STAB and STA-silica sol-gel (STA-SG compared with sulfuric acid. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W, and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74%, 531.5 eV followed by other O1s peak (9.26%, 532.8 eV were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity supported by silica via sol-gel technique. In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H2SO4 and the STAB gave high conversion of 100% and 98% but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94% but with a significantly higher GME selectivity of 95%, rendering it the more efficient solid acid catalyst.

  11. Microwave dielectric properties of BNT-BT0.08 thin films prepared by sol-gel technique

    Science.gov (United States)

    Huitema, L.; Cernea, M.; Crunteanu, A.; Trupina, L.; Nedelcu, L.; Banciu, M. G.; Ghalem, A.; Rammal, M.; Madrangeas, V.; Passerieux, D.; Dutheil, P.; Dumas-Bouchiat, F.; Marchet, P.; Champeaux, C.

    2016-04-01

    We report for the first time the microwave characterization of 0.92(Bi0.5Na0.5)TiO3-0.08BaTiO3 (BNT-BT0.08) ferroelectric thin films fabricated by the sol-gel method and integrated in both planar and out-of-plane tunable capacitors for agile high-frequency applications and particularly on the WiFi frequency band from 2.4 GHz to 2.49 GHz. The permittivity and loss tangent of the realized BNT-BT0.08 layers have been first measured by a resonant cavity method working at 12.5 GHz. Then, we integrated the ferroelectric material in planar inter-digitated capacitors (IDC) and in out-of-plane metal-insulator-metal (MIM) devices and investigated their specific properties (dielectric tunability and losses) on the whole 100 MHz-15 GHz frequency domain. The 3D finite-elements electromagnetic simulations of the IDC capacitances are fitting very well with their measured responses and confirm the dielectric properties determined with the cavity method. While IDCs are not exhibiting an optimal tunability, the MIM capacitor devices with optimized Ir/MgO(100) bottom electrodes demonstrate a high dielectric tunability, of 30% at 2.45 GHz under applied voltages as low as 10 V, and it is reaching 50% under 20 V voltage bias at the same frequency. These high-frequency properties of the MIM devices integrating the BNT-BT0.08 films, combining a high tunability under low applied voltages indicate a wide integration potential for tunable devices in the microwave domain and particularly at 2.45 GHz, corresponding to the widely used industrial, scientific, and medical frequency band.

  12. Titanium dioxide thin films deposited by the sol-gel technique starting from titanium oxy-acetyl acetonate: gas sensing and photocatalyst applications

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado, A.; Mayen-Hernandez, S.A.; L. Olvera, M. de la [Departamento de Ingenieria Electrica-SEES, Centro de Investigacion y de Estudios Avanzados del IPN, CINVESTAV-IPN, Mexico (Mexico); Tirado-Guerra, S. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, Mexico (Mexico)

    2010-09-15

    Titanium dioxide (TiO{sub 2}) thin films were deposited onto sodocalcic glass plates by the sol-gel technique, starting from a non-alkoxide route, namely, titanium oxy-acetyl acetonate as Ti precursor. Film thickness effect on both the gas sensing and photocatalytic degradation performance was studied. The as-deposited films were annealed in air at 400 C. All the X-ray spectra of the films show a very broad-peak centered in a 2{theta} angle around 30 . In the case of the thinnest films the surface morphology is uniform and very smooth, whereas for the thickest films the corresponding surface is covered by grains with a rod-like shape with a length on the order of 140 nm. The films were tested both for two straightforward applications: ultraviolet assisted-degradation of methylene blue dissolved in water, at different times, as well as gas sensor in a controlled propane (C{sub 3}H{sub 8}) atmosphere. As the film thickness increases, the degradation of methylene blue (MB) also increases. The thickest TiO{sub 2} thin films after being exposed by 5 hours to the catalytic degradation, promoted by ultraviolet illumination, showed a final MB solution degradation in the order of 48%. This result can be associated with the increase in the effective exposed area of the TiO{sub 2} thin films. On the other hand, the exposition of the films to a controlled propane atmosphere produced a significant change in the surface electrical resistance of the films at operating temperatures of 200 C and above. In fact, in the case of the thickest TiO{sub 2} films, a dramatic electrical resistance change of non-exposed and propane exposed - 560 to 0.7 M{omega} -, was registered. The results show that TiO{sub 2} films deposited by an economical deposition technique, as is the case of the sol-gel technique, could have an important potential in industrial applications. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Investigation of structural, optical and photocatalytic properties of mesoporous TiO 2 thin film synthesized by sol-gel templating technique

    Science.gov (United States)

    Janitabar-Darzi, S.; Mahjoub, A. R.; Nilchi, A.

    2009-12-01

    TiO 2 surfactant-templated nanostructured thin film was fabricated by supramolecular templating technique using TiCl 4 and P-123 as raw material and surfactant, respectively. The film was produced by Sol-gel dip coating procedure due to its simple technique as well as relatively low cost. Characterization of the product was carried out by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, thermogravimetry-differential scanning calorimetry (TG-DSC) and UV-vis absorption spectroscopy. The as-prepared TiO 2 film showed a quasi hexagonal mesostructure, and a further increase in the meso-scale order was observed after calcination. The prepared TiO 2 film had a high surface area of 124 m 2 g -1. The film was 2-μm thick and had a closely packed of anatase particles. The direct and indirect band gap of the film was estimated from UV-vis spectroscopy data to be 4.16 and 3.69 ev, respectively. The photocatalytic activity of the prepared TiO 2 film was evaluated by Congo Red degradation. The film had excellent photocatalytic efficiencies and more than 80% Congo Red was decolorized in 60 min.

  14. Influence of Ga doping ratio on the saturable absorption mechanism in Ga doped ZnO thin solid films processed by sol-gel spin coating technique

    Science.gov (United States)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.; Byrappa, K.

    2017-03-01

    In the present study, the nonlinear optical properties of sol-gel spin coated gallium doped zinc oxide (GZO) thin solid films are explored with nanosecond laser pulses using the z-scan technique. The higher doping ratios of Ga result in a large redshift of the energy gap (0.38 eV) due to the existence of enhanced grain boundary defects in GZO films. A positive nonlinear absorption coefficient is observed in undoped 1 at.wt.% GZO and 2 at.wt.% GZO films, and a negative nonlinear absorption coefficient in 3 at.wt.% GZO film. Fewer defects in undoped 1% GZO and 2% GZO films resulted in reverse saturable absorption (RSA), whereas a saturable absorption (SA) mechanism is observed in 3% GZO films and is attributed to the enhanced defect concentration in the band structure of GZO. However, all the films showed a self-defocusing mechanism, derived by a closed aperture z-scan technique. The present work sheds light on the defect mechanism involved in the observed nonlinear properties of GZO films.

  15. H{sub 2} separation from binary gas mixture using coated alumina-titania membrane by sol-gel technique at high-temperature region

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, A.L.; Othman, M.R. [Universiti Sains Malaysia, Penang (Malaysia). School of Chemical Engineering; Mukhtar, H. [University Technology of Petronas, Perak (Malaysia). Chemical Engineering Program

    2004-07-01

    A commercial tubular titania membrane was coated by alumina oxide using sol-gel technique. The membrane was used to separate pure gases of H{sub 2}, N{sub 2}, CO and CO{sub 2}. The permeabilities of H{sub 2} from a binary mixture of H{sub 2}/N{sub 2}, H{sub 2}/CO and H{sub 2}/CO{sub 2} were measured using the membrane at high-temperature region (1073 K). An experimental rig was designed and fabricated to perform the permeability studies of H{sub 2} from the binary gas mixture. Effect of feed rate, feed concentration and average pressure on permeability of pure gas and a binary mixture of H{sub 2} were studied. Results showed that the H{sub 2} separation factor for binary mixture of H{sub 2}/CO{sub 2} is the highest followed by H{sub 2}/CO and H{sub 2}/N{sub 2} for all feed concentration. The permeability of gases across the simple alumina-titania composite membrane increased slightly with increase of average pressure. Experimental data were compared with the theoretical values using complete mixing model and the separation factor was calculated experimentally and theoretically. The results showed a good agreement between experimental data and the theoretical predictions. The permeability of gases across the coated alumina-titania composite membrane increased slightly with increase of average pressure. (Author)

  16. Optical, structural and morphological studies of (ZnO) nano-rod thin films for biosensor applications using sol gel technique

    Science.gov (United States)

    Wahab, H. A.; Salama, A. A.; El-Saeid, A. A.; Nur, O.; Willander, M.; Battisha, I. K.

    Uniformly distributed ZnO nano-rods (NRs) with diameters in nano-scale have been successfully grown in two stages; the first at annealing temperature (250-300 °C) for seed layer preparation on glass substrate by using sol gel technique and the second at low temperature (90-95 °C) by aqueous chemical growth (ACG) method. The same prepared thin film samples were grown on the surface of silver wire (0.25 mm in diameters) to produce electrochemical nano-sensors. The structure and the morphology of the prepared samples will be evaluated using XRD, Scanning electron microscope SEM. The absorption coefficient (α) and the band gap (Eg) for ZnO NRs thin films were determined. (α) was decreased by increasing the annealing temperature due to the increase of the surface roughness caused by higher temperature, where the creation of surface roughness gives rise to multi-reflections which, capture the reflected radiation and enhance the absorptivity. We are presenting an iron ion (Fe3+) potentiometric sensor based on functionalized ZnO nano-rods with selective iono-phore (18 crown 6). Zinc oxide nanorods (NRs) thin films with a diameter of about 68 up to 94 nm were grown on silver wire and gold coated glass.

  17. Crystallization, crystal structure, and isothermal melt crystallization kinetics of novel polyamide 6/SiO2 nanocomposites prepared using the sol-gel technique.

    Science.gov (United States)

    Rafique, Fatima Zohra; Vasanthan, Nadarajah

    2014-08-07

    Polyamide 6/SiO2 (PA6/SiO2) nanocomposites with varying amounts of SiO2 were prepared by using a novel sol-gel technique. These nanocomposites were formed in situ by hydrolysis and through the condensation of tetraethoxysilane (TEOS) using formic acid with a small amount of water as the solvent for PA6. Observations of TGA showed that the thermal stability of PA6 nanocomposite was significantly improved compared to that of neat PA6. Microstructure development during the thermally induced crystallization of PA6/SiO2 nanocomposites was investigated with a combination of differential scanning calorimetry (DSC), FTIR spectroscopy, scanning electron microscopy (SEM), and AFM. FTIR spectroscopy was used to determine the crystal form of these nanocomposites, and it was concluded that SiO2 nanoparticles have the γ-nucleating effect. The crystallinity of nanocomposites decreased with increasing TEOS loading as compared to that for neat PA6. SEM showed a very fine dispersion of nanoscale silica whereas SEM and Zetasizer proved the silica particle size was about 100-200 nm. The isothermal crystallization kinetics of these nanocomposites with increasing SiO2 content were investigated, and it was shown that the amount of SiO2 plays a significant role in crystallization kinetics.

  18. A study of PbTiO sub 3 crystallization in pure and composite nanopowders prepared by the sol-gel technique

    CERN Document Server

    Cernansky, M; Kral, K; Krupkova, R

    2002-01-01

    In this investigation the crystallization of PbTiO sub 3 upon annealing of pure nanopowders and PbTiO sub 3 -SiO sub 2 (1:1 v/v) nanocomposite powders prepared by the sol-gel technique was studied. Using x-ray diffraction phase analysis, the start of PbTiO sub 3 crystallization in pure PbTiO sub 3 powders was detected at 400 sup o C. Distinct crystallization of PbTiO sub 3 in PbTiO sub 3 -SiO sub 2 nanocomposites starts at 700 sup o C, whereas SiO sub 2 remains amorphous. There are indications that an interface interaction between the PbTiO sub 3 and the SiO sub 2 phase plays an important role in hindering the crystallization of PbTiO sub 3. The particle size (size of coherently scattering regions) was estimated from the broadening of the x-ray diffraction line profiles. The average size of PbTiO sub 3 nanocrystallites increases with temperature and time of annealing, the influence of temperature being more significant than that of the annealing time. Differential scanning calorimetry confirmed the results of...

  19. The Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Khalid Suliman Aboodh

    2015-02-01

    Full Text Available Abstract An increasingly important application of liquid jets is the disintegration of the jet to form droplets of liquid containing nuclear fuel. These droplets are then dried and sintered to form ceramic micro spheres for use in fuel elements in nuclear reactors. The total operations required to form the droplets convert them to solids and fire them to ceramic bodies comprise what are known as Sol-Gel processes Reference 13.

  20. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  1. 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.

  2. 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 Pveneering porcelain.

  3. Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

    Science.gov (United States)

    Mirzaee, Majid; Dolati, Abolghasem

    2014-09-01

    Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

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

    Science.gov (United States)

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

  5. Radiation hardening in sol-gel derived Er{sup 3+}-doped silica glasses

    Energy Technology Data Exchange (ETDEWEB)

    Hari Babu, B., E-mail: hariphy2012@gmail.com, E-mail: matthieu.lancry@u-psud.fr; León Pichel, Mónica [Laboratoire des Solides Irradiés, UMR CEA-CNRS 7642, Ecole Polytechnique, Université Paris Saclay, 91128 Palaiseau (France); Institut de Chimie Moléculaire et des Matériaux d' Orsay, UMR CNRS-UPSud 8182, Université Paris Sud, 91405 Orsay (France); Ollier, Nadège [Laboratoire des Solides Irradiés, UMR CEA-CNRS 7642, Ecole Polytechnique, Université Paris Saclay, 91128 Palaiseau (France); El Hamzaoui, Hicham; Bigot, Laurent; Savelii, Inna; Bouazaoui, Mohamed [Laboratoire PhLAM (UMR CNRS 8523), IRCICA (USR CNRS 3380), CERLA - FR CNRS 2416, Université Lille 1, Villeneuve d' Ascq Cedex F-59655 (France); Poumellec, Bertrand; Lancry, Matthieu, E-mail: hariphy2012@gmail.com, E-mail: matthieu.lancry@u-psud.fr [Institut de Chimie Moléculaire et des Matériaux d' Orsay, UMR CNRS-UPSud 8182, Université Paris Sud, 91405 Orsay (France); Ibarra, Angel [National Fusion Laboratory, CIEMAT, Avda Complutense 40, 28040 Madrid (Spain)

    2015-09-28

    The aim of the present paper is to report the effect of radiation on the Er{sup 3+}-doped sol-gel silica glasses. A possible application of these sol-gel glasses could be their use in harsh radiation environments. The sol-gel glasses are fabricated by densification of erbium salt-soaked nanoporous silica xerogels through polymeric sol-gel technique. The radiation-induced attenuation of Er{sup 3+}-doped sol-gel silica is found to increase with erbium content. Electron paramagnetic resonance studies reveal the presence of E′{sub δ} point defects. This happens in the sol-gel aluminum-silica glass after an exposure to γ-rays (kGy) and in sol-gel silica glass after an exposure to electrons (MGy). The concentration levels of these point defects are much lower in γ-ray irradiated sol-gel silica glasses. When the samples are co-doped with Al, the exposure to γ-ray radiation causes a possible reduction of the erbium valence from Er{sup 3+} to Er{sup 2+} ions. This process occurs in association with the formation of aluminum oxygen hole centers and different intrinsic point defects.

  6. The Influence of the Polymer Amount on the Biological Properties of PCL/ZrO2 Hybrid Materials Synthesized via Sol-Gel Technique

    Directory of Open Access Journals (Sweden)

    Michelina Catauro

    2017-10-01

    Full Text Available Organic/inorganic hybrid materials are attracting considerable attention in the biomedical area. The sol-gel process provides a convenient way to produce many bioactive organic–inorganic hybrids. Among those, poly(e-caprolactone/zirconia (PCL/ZrO2 hybrids have proved to be bioactive with no toxic materials. The aim of this study was to investigate the effects of these materials on the cellular response as a function of the PCL content, in order to evaluate their potential use in the biomedical field. For this purpose, PCL/ZrO2 hybrids containing 6, 12, 24, and 50 wt % of PCL were synthesized by the sol-gel method. The effects of their presence on the NIH-3T3 fibroblast cell line carrying out direct cell number counting, MTT, cell damage assays, flow cytometry-based analysis of cell-cycle progression, and immunoblotting experiments. The results confirm and extend the findings that PCL/ZrO2 hybrids are free from toxicity. The hybrids containing 12 and 24 wt % PCL, (more than 6 and 50 wt % ones enhance cell proliferation when compared to pure ZrO2 by affecting cell cycle progression. The finding that the content of PCL in PCL/ZrO2 hybrids differently supports cell proliferation suggests that PCL/ZrO2 hybrids could be useful tools with different potential clinical applications.

  7. Sol-gel deposited electrochromic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, N.; Lampert, C.M.

    1995-06-01

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

  8. 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.

  9. Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, A.J., E-mail: antoniojulio.lopez@urjc.es [Dept. de Ciencia e Ingenieria de Materiales, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain); Rico, A.; Rodriguez, J.; Rams, J. [Dept. de Ciencia e Ingenieria de Materiales, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain)

    2010-08-15

    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.

  10. Nano-structure TiO2 film coating on 316L stainless steel via sol-gel technique for blood compatibility improvement

    Directory of Open Access Journals (Sweden)

    Mohammadreza Foruzanmehr

    2014-04-01

    Full Text Available   Objective(s: Titanium oxides are known to be appropriate hemocompatible materials which are suggested as coatings for blood-contacting devices. Little is known about the influence of nanometric crystal structure, layer thickness, and semiconducting characteristics of TiO2 on blood hemostasis.   Materials and Methods: Having used sol-gel dip coating method in this study, TiO2 thin films were deposited on nano-scale electro-polished stainless steel 316L with 1 to 5 nano-sized layers. Surface morphology and structure of the film were studied with X-ray diffraction and atomic force microscopy. Blood compatibility was also determined by measuring the platelet activation (CD62P expression, platelet adhesion (Scanning Electron Microscopy, and the blood clotting time on these samples. Results: The films were compact and smooth and existed mainly in the form of anatase. By increasing the number of TiO2 thin layer, clotting time greatly extended, and the population of activated platelet and P-selectine expression changed according to the surface characteristics of each layer. Conclusion: The findings revealed that stainless steel 316L coated with nano-structured TiO2 layer improved blood compatibility, in terms of both blood platelet activity and coagulation cascade, which can decrease the thrombogenicity of blood contacting devices which were made from stainless steel.

  11. Influence of PCL on mechanical properties and bioactivity of ZrO2-based hybrid coatings synthesized by sol-gel dip coating technique.

    Science.gov (United States)

    Catauro, Michelina; Bollino, Flavia; Veronesi, Paolo; Lamanna, Giuseppe

    2014-06-01

    The biological properties of medical implants can be enhanced through surface modifications such as to provide a firm attachment of the implant. In this study, organic-inorganic hybrid coatings have been synthesized via sol-gel dip coating. They consist of an inorganic ZrO2 matrix in which different amounts of poly(ε-caprolactone) have been entrapped to improve the mechanical properties of the films. The influence of the PCL amount on the microstructural, biological and mechanical properties of the coating has been investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses have shown that the hybrids used for the coating are homogenous and totally amorphous materials; Fourier transform infrared spectroscopy (FT-IR) has demonstrated that hydrogen bonds arise between the organic and inorganic phases. SEM and atomic force microscopy (AFM) have highlighted the nanostructured nature of the film. SEM and EDS analyses, after soaking the samples in a simulated body fluid (SBF), have pointed out the apatite formation on the coating surface, which proves the bone-bonding ability of the nanocomposite bioactive films. Scratch and nano-indentation tests have shown that the coating hardness, stiffness and Young's modulus decrease in the presence of large amounts of the organic phase. Copyright © 2014. Published by Elsevier B.V.

  12. Synthesis of Hollow Sphere and 1D Structural Materials by Sol-Gel Process.

    Science.gov (United States)

    Li, Fa-Liang; Zhang, Hai-Jun

    2017-08-25

    The sol-gel method is a simple and facile wet chemical process for fabricating advanced materials with high homogeneity, high purity, and excellent chemical reactivity at a relatively low temperature. By adjusting the processing parameters, the sol-gel technique can be used to prepare hollow sphere and 1D structural materials that exhibit a wide application in the fields of catalyst, drug or gene carriers, photoactive, sensors and Li-ion batteries. This feature article reviewed the development of the preparation of hollow sphere and 1D structural materials using the sol-gel method. The effects of calcination temperature, soaking time, pH value, surfactant, etc., on the preparation of hollow sphere and 1D structural materials were summarized, and their formation mechanisms were generalized. Finally, possible future research directions of the sol-gel technique were outlined.

  13. Synthesis of Hollow Sphere and 1D Structural Materials by Sol-Gel Process

    Science.gov (United States)

    Li, Fa-Liang; Zhang, Hai-Jun

    2017-01-01

    The sol-gel method is a simple and facile wet chemical process for fabricating advanced materials with high homogeneity, high purity, and excellent chemical reactivity at a relatively low temperature. By adjusting the processing parameters, the sol-gel technique can be used to prepare hollow sphere and 1D structural materials that exhibit a wide application in the fields of catalyst, drug or gene carriers, photoactive, sensors and Li-ion batteries. This feature article reviewed the development of the preparation of hollow sphere and 1D structural materials using the sol-gel method. The effects of calcination temperature, soaking time, pH value, surfactant, etc., on the preparation of hollow sphere and 1D structural materials were summarized, and their formation mechanisms were generalized. Finally, possible future research directions of the sol-gel technique were outlined. PMID:28841188

  14. Luminescent hybrid porphyrinosilica obtained by sol gel chemistry

    Directory of Open Access Journals (Sweden)

    Neri Cláudio Roberto

    2003-01-01

    Full Text Available The sol-gel process is a methodology used to obtain organic-inorganic hybrid solids, which open new possibilities in the field of material science. The sol-gel technique offers a low temperature attractive approach for introducing organic molecules into amorphous materials. In order to introduce tetrakis (2-hydroxy-5-nitrophenylporphyrin covalently bounded to a silicate matrix, the inorganic precursor 3-isocyanatopropyltriethoxysilane was added (molar ratio 2:1 to the porphyrin solution in anhydrous dimethylformamide and triethylamine. The isolated porphyrin and the hybrid porphyrinosilica have excitation maximum centred at 400 nm and 424 nm, respectively and the emission spectra for both materials has bands centred at 650 nm and 713 nm. The formation of hybrid matrix was investigated by FTIR.

  15. Sol-gel synthesis of carbon based materials reinforced ultra high temperature ceramic composites

    OpenAIRE

    Wang, Xiaojing

    2017-01-01

    This Ph.D. research is based on the development of novel sol-gel techniques for synthesis of nanostructured ultra high temperature ceramics (UHTCs) and subsequent spark plasma sintering (SPS) for densifying the UHTC composites. The liquid nature of the sol-gel process offers advantages such as high purity and ability for mixing and infiltration, and thus it can overcome some shortcomings of the conventional power processing of ceramics. SPS delivers microstructures with good density and fine ...

  16. Electrophoretic Porosimetry of Sol-Gels

    Science.gov (United States)

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

    2000-01-01

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

  17. Sol-gel processing of bioactive glass nanoparticles: A review.

    Science.gov (United States)

    Zheng, Kai; Boccaccini, Aldo R

    2017-03-21

    Silicate-based bioactive glass nanoparticles (BGN) are gaining increasing attention in various biomedical applications due to their unique properties. Controlled synthesis of BGN is critical to their effective use in biomedical applications since BGN characteristics, such as morphology and composition, determining the properties of BGN, are highly related to the synthesis process. In the last decade, numerous investigations focusing on BGN synthesis have been reported. BGN can mainly be produced through the conventional melt-quench approach or by sol-gel methods. The latter approaches are drawing widespread attention, considering the convenience and versatility they offer to tune the properties of BGN. In this paper, we review the strategies of sol-gel processing of BGN, including those adopting different catalysts for initiating the hydrolysis and condensation of silicate precursors as well as those combining sol-gel chemistry with other techniques. The processes and mechanism of different synthesis approaches are introduced and discussed in detail. Considering the importance of the BGN morphology and composition to their biomedical applications, strategies put forward to control the size, shape, pore structure and composition of BGN are discussed. BGN are particularly interesting biomaterials for bone-related applications, however, they also have potential for other biomedical applications, e.g. in soft tissue regeneration/repair. Therefore, in the last part of this review, recently reported applications of BGN in soft tissue repair and wound healing are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation

    Directory of Open Access Journals (Sweden)

    Jolanta Gąsiorek

    2018-01-01

    Full Text Available Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented.

  19. Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation.

    Science.gov (United States)

    Gąsiorek, Jolanta; Szczurek, Anna; Babiarczuk, Bartosz; Kaleta, Jerzy; Jones, Walis; Krzak, Justyna

    2018-01-26

    Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented.

  20. The Sol-Gel-Xerogel Transition

    Science.gov (United States)

    1993-11-01

    relative mobili- ty are supported by the ESR (Electron Spin Resonance) studies of * * * Ikoma et al. [301 demonstrating that polyamine copper(II) chelates...deactivation of the triplet state of the molecule in the case of RTP. Recent studies on the photoisomerization of azobenzene in sol-gel glass films by

  1. Sol-gel modification of wood substrates to retard weathering

    Science.gov (United States)

    Mandla A Tshabalala; Sam Williams

    2008-01-01

    Wood specimens were treated with sol-gel systems based on metalorganic precursors of silicon (Si), iron (Fe), zirconium (Zr), and titanium (Ti). The effect of these sol-gel systems on weathering properties of wood was investigated. These sol-gel systems were found to have a positive effect on surface color stability and water vapor resistance of the specimens. Under...

  2. Epoxy Sol-Gel Hybrid Thermosets

    Directory of Open Access Journals (Sweden)

    Angels Serra

    2016-02-01

    Full Text Available Sol-gel methodologies are advantageous in the preparation of hybrid materials in front of the conventional addition of nanoparticles, because of the fine dispersion of the inorganic phase that can be reached in epoxy matrices. In addition, the use of organoalkoxysilanes as coupling agents allows covalent linkage between organic and inorganic phases, which is the key point in the improvement of mechanical properties. The sol-gel process involves hydrolysis and condensation reactions under mild conditions, starting from hydrolysable metal alkoxides, generally alkoxy silanes. Using the sol-gel procedure, the viscosity of the formulation is maintained, which is an important issue in coating applications, whereas the transparency of the polymer matrix is also maintained. However, only the proper combination of the chemistries and functionalities of both organic and inorganic structures leads to thermosets with the desired characteristics. The adequate preparation of hybrid epoxy thermosets enables their improvement in characteristics such as mechanical properties (modulus, hardness, scratch resistance, thermal and flame resistance, corrosion and antimicrobial protection, and even optical performance among others.

  3. Investigation of high temperature sol-gel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, M. [DTU Mekanik, Kgs. Lyngby (Denmark); Vilhelmsen, T. [Vattenfall Heat Nordic, Copenhagen (Denmark); Bennedsen, J. [Teknologisk Institut, Aarhus (Denmark)

    2008-03-15

    The Danish Technological Institute (DTI) has developed a technique using Hybrid Sol-gel nanotechnology to produce coatings which can change the surface characteristics of various components. It is the purpose of this project to investigate where such coatings can be utilised in the power generating industry with respect to fouling and corrosion resistance. Sol-gel coatings were fabricated at DTI with the aim of being high temperature corrosion resistance. These coatings were investigated at DTU Mechanical Engineering. The coatings contained large amounts of aluminium, oxygen, silicon and titanium with also addition of mica. Tubes of various alloys (15Mo3, X20CrMoV121, TP347H and P91,) were received from DONG Energy/Vattenfall. They were mechanically cleaned and then 15Mo3, X20CrMoV121 and TP347H were cleaned in a 10% melamine solution for 30 minutes. All tubes were then polished and coated. Two different sol-gel coatings have been applied to each end of the tube. The one coating is white ({Psi}114) and the other black ({Psi}115). The specimens were heated for 3 thermal cycle periods of 8 hours. From the analysis of the various coatings, it is clear that the coatings exposed to thermal cycles of 500 deg. C have all oxides present below the sol-gel layer. In many cases especially for the grey coating, the coating has spalled. Thus these coatings do not prevent permeation of oxidising species either due to a permable coating or cracking of the coating due to thermal cycling. For the coating on the 15Mo3 tube, there was almost no oxide, however microscopy of the surface of the specimens revealed cracking. It is suggested that lack of oxide or very thin oxide on the 15Mo3 is due to the fact that oxidation is not so fast at 400 deg. C compared to 500 deg. C, and that a longer exposure time would have given a thicker oxide. It would be difficult to understand why 15Mo3 behaves differently to the under ferritic steels when it has a lower corrosion resistance and similar

  4. 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

  5. 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.

  6. Connectivity in sol-gel silica glasses

    Directory of Open Access Journals (Sweden)

    Wander L. Vasconcelos

    1998-07-01

    Full Text Available In this work it is carried out a review on structural parameters related to the evaluation of pore connectivity of nanostructures. The work describes parameters and methods of evaluation of geometric parameters. The concepts of connectivity are applied to silica gels and glasses obtained from sol-gel process. The study of pores connectivity was carried out using a combination of geometric modeling and experimental evaluation of specific surface area and pore volume. The permeability of the pore structure is evaluated and a permeability geometric factor, Pg, is proposed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kueper, T.W.

    1992-05-01

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

  8. Processing and Characterization of Sol-Gel Cerium Oxide Microspheres

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Zachary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Padilla Cintron, Cristina [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-27

    Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.

  9. 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.

  10. Sol-gel precursors and products thereof

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  11. Ionic-liquid-mediated poly(dimethylsiloxane)- grafted carbon nanotube fiber prepared by the sol-gel technique for the head space solid-phase microextraction of methyl tert-butyl ether using GC.

    Science.gov (United States)

    Vatani, Hossein; Yazdi, Ali Sarafraz

    2014-01-01

    A headspace solid-phase microextraction method was developed for the preconcentration and extraction of methyl tert-butyl ether. An ionic-liquid-mediated multiwalled carbon nanotube-poly(dimethylsiloxane) hybrid coating, which was prepared by covalent functionalization of multiwalled carbon nanotubes with hydroxyl-terminated poly(dimethylsiloxane) using the sol-gel technique, was used as solid-phase microextraction adsorbent. This innovative fiber exhibited a highly porous surface structure, high thermal stability (at least 320°C) and long lifespan (over 210 uses). Potential factors affecting the extraction efficiency were optimized. Under the optimum conditions, the method LOD (S/N = 3) was 0.007 ng/mL and the LOQ (S/N = 10) was 0.03 ng/mL. The calibration curve was linear in the range of 0.03-200 ng/mL. The RSDs for one fiber (repeatability, n = 5) at three different concentrations (0.05, 1, and 150 ng/mL) were 5.1, 4.2, and 4.6% and for the fibers obtained from different batches (reproducibility, n = 3) were 6.5, 5.9, and 6.3%, respectively. The developed method was successfully applied to the determination of methyl tert-butyl ether in different real water samples on three consecutive days. The relative recoveries for the spiked samples with 0.05, 1, and 150 ng/mL were between 94-104%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. OPTICAL PROPERTIES OF Al:ZnO THIN FILM DEPOSITED BY DIFFERENT SOL-GEL TECHNIQUES: ULTRASONIC SPRAY PYROLYSIS AND DIP-COATING

    Directory of Open Access Journals (Sweden)

    Ebru Gungor

    2016-08-01

    Full Text Available Undoped and Al-doped ZnO polycrystalline thin films have been fabricated on glass substrates by using a computer-controlled dip coating (DC and ultrasonic spray pyrolysis (USP systems. The film deposition parameters of DC process were optimized for the samples. In this technique, the substrate was exposed to temperature gradient using a tube furnace. In the study, the other solvent-based technique was conventional USP. The zinc salt and Al salt concentrations in the solution were kept constant as 0.1 M and 2% of Zn salt’s molarity, respectively. The optical properties were compared for the films deposited two different techniques. The optical transmission of Al:ZnO/Glass/Al:ZnO sample dip coated and  the optical transmission of Al:ZnO/Glass sample ultrasonically sprayed were determined higher than 80% in the visible and near infrared region. Experimental optical transmittance spectra of the films in the forms of FilmA/Glass/FilmA and FilmA/glass were used to determine the optical constants. It was observed that the optical band gaps of Al doped ZnO films onto glass substrate were increases with increase of Al content and the absorption edge shifted to the shorter wavelength (blue shift compared with the undoped ZnO thin film.

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

    Science.gov (United States)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    Sol-gel synthesis in reduced gravity is a relatively new topic in the literature and further inves-tigation is essential to realise its potential and application to other sol-gel systems. The sol-gel technique has been successfully applied to the synthesis of silica systems of varying porosity for many diverse applications [1-5]. It is proposed that current methods for the synthesis of silica sol-gels in reduced gravity may be applied to titanium sol-gel processing in order to enhance desirable physical and chemical characteristics of the final materials. The physical and chemical formation mechanisms for titanium alkoxide based sol-gels, to date, is not fully understood. However, various authors [6-9] have described potential methods to control the hydrolysis and condensation reactions of titanium alkoxides through the use of chemical inhibitors. A preliminary study of the reaction kinetics of titanium alkoxide sol-gel reaction in normal gravity was undertaken in order to determine reactant mixtures suitable for further testing under varied gravity conditions of limited duration. Through the use of 1H Nuclear Magnetic Resonance spectroscopy (NMR) for structural analysis of precursor materials, Ultra-Violet-Visible spectroscopy (UV-VIS) and viscosity measurements, it was demonstrated that not only could the rate of the chemical reaction could be controlled, but directed linear chain growth within the resulting gel structure was achievable through the use of increased inhibitor concentrations. Two unique test systems have been fabricated to study the effects of varied gravity (reduced, normal, high) on the formation of titanium sol-gels. Whilst the first system is to be used in conjunction with the recently commissioned drop tower facility at Queensland University of Technology in Brisbane, Australia to produce reduced gravity conditions. The second system is a centrifuge capable of providing high gravity environments of up to 70 G's for extended periods of time

  14. Investigation of Sol-Gel coatings exposed in the condenser at Fynsvaerket. Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, M. [DTU Management Engineering, Kgs. Lyngby (Denmark); Vilhelmsen, T. [Vattenfall Heat Nordic, Copenhagen (Denmark)

    2007-10-15

    The Danish Technological Institute (DTI) has developed a coatings technique using Hybrid Sol-gel nanotechnology to produce coatings which can change the surface characteristics of various components. It is the purpose of this project to investigate where such coatings can be utilised in the power generating industry with respect to fouling and corrosion resistance. Four different sol-gel coatings have been applied to brass condenser tubes about 10 cm in length. The coatings are termed 23, 35, 38, 46. The exact composition of these different coatings was not given. These sections were mounted in the water chamber inlet before the tubes into the condenser and another set were placed on the condenser plate at the outlet. The condenser tube has a composition 76 wt.% Cu, 22 wt.% Zn and 2 wt.% Al corresponding to an aluminium brass. Based on the visual appearance of the four coatings it is clear that Sol-gel 38 does not reduced biological fouling and rust spots can be clearly seen on Sol-gel 46. Thus based on visual appearance, sol-gel 23 and sol-gel 35 are most promising. Due to the presence of corrosion products on the inner side of the unexposed tubes which influences the adherence and protectiveness of coatings applied, the inner side cannot be used to assess the coatings performance. In the next exposure test, better initial cleaning of the tubes is required. Based on visual assessment, Sol-gel 38 has not solved the problems with biological fouling compared to the other coatings. With respect to corrosion, it is observed that in all cases there are corrosion products, either chlorides or oxides/hydroxides/carbonates, present in the interface between the tube and the coating. Coating 38 also experienced lack of adhesion. This could be triggered by a build up of corrosion products under the coating which would eventually lead to delaminating of the coating. Whether the corrosion rate has been decreased compared to the uncoated tubes is not known, however in the next

  15. Outdoor weathering of sol-gel-treated wood

    Science.gov (United States)

    Mandla A Tshabalala; Ryan Libert; Nancy Ross Sutherland

    2009-01-01

    Outdoor weathering of wood specimens treated with sol-gel formulations based on methyltrimethoxysilane (MTMOS), hexadecyltrimethoxysilane (HDTMOS), and ferric-zirconia-titania (Fe-Zr-Ti) sol was evaluated. The sol-gel process allowed deposition of a thin film of hybrid inorganic-organic networks (gel) in the wood cell wall that resulted in improved outdoor weathering...

  16. 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…

  17. 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.

  18. Self-Healing Corrosion Protective Sol-Gel Coatings

    NARCIS (Netherlands)

    Abdolah Zadeh, M.

    2016-01-01

    Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic

  19. Sol-gel route to functional and hierarchical ceramic matrix composites

    Science.gov (United States)

    Colomban, Ph.

    1996-04-01

    The use of sol-gel technique to fabricate functionally graded ceramic matrix composites reinforced with woven fibers is illustrated with composites made by alternating dielectric and conducting layers (microwave absorbent) or by alternating materials that have high hardness and good corrosion resistance. Emphasis on the preparation of multiscale reinforced composites is given according to the idea of biomimetic materials.

  20. Analysis and theory of gas transport in microporous sol-gel derived ceramic membranes

    NARCIS (Netherlands)

    de Lange, R.S.A.; de Lange, Rob; Keizer, Klaas; Burggraaf, Anthonie; Burggraaf, A.J.

    1995-01-01

    Sol-gel modification of mesoporous alumina membranes is a very successful technique to improve gas separation performance. Due to the formed microporous top layer, the membranes show activated transport and molecular sieve-like separation factors. This paper concentrates on the mechanism of

  1. 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.

  2. Silica-Based Sol-Gel Coating on Magnesium Alloy with Green Inhibitors

    Directory of Open Access Journals (Sweden)

    Vinod Upadhyay

    2017-06-01

    Full Text Available In this work, the performances of several natural organic inhibitors were investigated in a sol-gel system (applied on the magnesium alloy Mg AZ31B substrate. The inhibitors were quinaldic acid (QDA, betaine (BET, dopamine hydrochloride (DOP, and diazolidinyl urea (DZU. Thin, uniform, and defect-free sol-gel coatings were prepared with and without organic inhibitors, and applied on the Mg AZ31B substrate. SEM and EDX were performed to analyze the coating surface properties, the adhesion to the substrate, and the thickness. Electrochemical measurements, including electrochemical impedance spectroscopy (EIS and anodic potentiodynamic polarization scan (PDS, were performed on the coated samples to characterize the coatings’ protective properties. Also, hydrogen evolution measurement—an easy method to measure magnesium corrosion—was performed in order to characterize the efficiency of coating protection on the magnesium substrate. Moreover, scanning vibrating electrode technique (SVET measurements were performed to examine the efficiency of the coatings loaded with inhibitors in preventing and containing corrosion events in defect areas. From the testing results it was observed that the formulated sol-gel coatings provided a good barrier to the substrate, affording some protection even without the presence of inhibitors. Finally, when the inhibitors’ performances were compared, the QDA-doped sol-gel was able to contain the corrosion event at the defect.

  3. Industrial solvents analyzed on SolGel-WAX(TM)

    National Research Council Canada - National Science Library

    Angus Hibberd; Gerard Sharp; Dan DiFeo

    2002-01-01

    ... phase-bonding process in which the polyethylene glycol phase is encapsulated into a sol-gel matrix. The SolGel-WAX column, by the nature of the sol-gel bonding, is an extremely inert, low-bleed, high-temperature column. This inertness gives excellent peak shape of difficult-to-- analyze polar solvents. The high thermal stability gives a low-bleed column and therefore higher signal-to-noise ratio allowing lower detection limits, which is essential in many industrial processes. Also note the excellent separa...

  4. A new sol-gel process for producing Na(2)O-containing bioactive glass ceramics.

    Science.gov (United States)

    Chen, Qi-Zhi; Li, Yuan; Jin, Li-Yu; Quinn, Julian M W; Komesaroff, Paul A

    2010-10-01

    The sol-gel process of producing SiO(2)-CaO bioactive glasses is well established, but problems remain with the poor mechanical properties of the amorphous form and the bioinertness of its crystalline counterpart. These properties may be improved by incorporating Na(2)O into bioactive glasses, which can result in the formation of a hard yet biodegradable crystalline phase from bioactive glasses when sintered. However, production of Na(2)O-containing bioactive glasses by sol-gel methods has proved to be difficult. This work reports a new sol-gel process for the production of Na(2)O-containing bioactive glass ceramics, potentially enabling their use as medical implantation materials. Fine powders of 45S5 (a Na(2)O-containing composition) glass ceramic have for the first time been successfully synthesized using the sol-gel technique in aqueous solution under ambient conditions, with the mean particle size being approximately 5 microm. A comparative study of sol-gel derived S70C30 (a Na(2)O-free composition) and 45S5 glass ceramic materials revealed that the latter possesses a number of features desirable in biomaterials used for bone tissue engineering, including (i) the crystalline phase Na(2)Ca(2)Si(3)O(9) that couples good mechanical strength with satisfactory biodegradability, (ii) formation of hydroxyapatite, which may promote good bone bonding and (iii) cytocompatibility. In contrast, the sol-gel derived S70C30 glass ceramic consisted of a virtually inert crystalline phase CaSiO(3). Moreover, amorphous S70C30 largely transited to CaCO(3) with minor hydroxyapatite when immersed in simulated body fluid under standard tissue culture conditions. In conclusion, sol-gel derived Na(2)O-containing glass ceramics have significant advantages over related Na(2)O-free materials, having a greatly improved combination of mechanical capability and biological absorbability. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Investigations of the small-scale thermal behavior of sol-gel thermites.

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Mial E.; Farrow, Matthew; Tappan, Alexander Smith

    2009-02-01

    Sol-gel thermites, formulated from nanoporous oxides and dispersed fuel particles, may provide materials useful for small-scale, intense thermal sources, but understanding the factors affecting performance is critical prior to use. Work was conducted on understanding the synthesis conditions, thermal treatments, and additives that lead to different performance characteristics in iron oxide sol-gel thermites. Additionally, the safety properties of sol-gel thermites were investigated, especially those related to air sensitivity. Sol-gel thermites were synthesized using a variety of different techniques and there appear to be many viable routes to relatively equivalent thermites. These thermites were subjected to several different thermal treatments under argon in a differential scanning calorimeter, and it was shown that a 65 C hold for up to 200 minutes was effective for the removal of residual solvent, thus preventing boiling during the final thermal activation step. Vacuum-drying prior to this heating was shown to be even more effective at removing residual solvent. The addition of aluminum and molybdenum trioxide (MoO{sub 3}) reduced the total heat release per unit mass upon exposure to air, probably due to a decrease in the amount of reduced iron oxide species in the thermite. For the thermal activation step of heat treatment, three different temperatures were investigated. Thermal activation at 200 C resulted in increased ignition sensitivity over thermal activation at 232 C, and thermal activation at 300 C resulted in non-ignitable material. Non-sol-gel iron oxide did not exhibit any of the air-sensitivity observed in sol-gel iron oxide. In the DSC experiments, no bulk ignition of sol-gel thermites was observed upon exposure to air after thermal activation in argon; however ignition did occur when the material was heated in air after thermal treatment. In larger-scale experiments, up to a few hundred milligrams, no ignition was observed upon exposure to air

  6. 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.

  7. 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...

  8. 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.

  9. Investigation of Sol-Gel coatings exposed in the condenser at Fynsvaerket. Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, M. [DTU Management Engineering, Kgs. Lyngby (Denmark); Vilhelmsen, T. [Vattenfall Heat Nordic, Copenhagen (Denmark); Bennedsen, J. [Teknologisk Institut, Aarhus (Denmark)

    2008-12-15

    The Danish Technological Institute (DTI) has developed a technique using Hybrid Sol-gel nanotechnology to produce coatings which can change the surface characteristics of various components. It is the purpose of this project to investigate where such coatings can be utilised in the power generating industry with respect to fouling and corrosion resistance. Sol-gel coatings have glass-ceramic properties and their fundamental chemical structure is based on silanes (methane where carbon is replaced with silicon) with an amorphous (not crystalline) structure. The basic structure can be modified with various metallic nanoparticles to change the properties of the coatings. In the sol-gel process, the liquid reagents are mixed together to form a sol-gel which is then applied on the surface of a component either by dipping or painting. After that the component is cured at a temperature of 160 deg. C to result in a glass ceramic surface. A report has been written with the initial results with sol-gel coatings on the condenser tubes at Fysnvaerket. Due to the presence of corrosion products on the unexposed tubes which influences the adherence and protectiveness of coatings applied, the effect of sol-gel coatings were difficult to assess. Two different sol-gel coatings have been applied to brass condenser tubes about 10 cm in length. Based on the experience from previous exposures, the surface of the condenser tubes was mechanically cleaned before coating with the sol-gel components. One set was sandblasted and the other set was grinded to a polished finish using sandpaper. The specimens grinded and polished were exposed tubes that had been removed from the condenser. Sections of unexposed cleaned condenser tubes with and without sol-gel are also investigated as control specimens. Before application of the coatings, the tubes were mechanically cleaned either by sandblasting or by grinding to a polished finish. The exact composition of these different coatings was not known

  10. Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

    Science.gov (United States)

    Bakas, Idriss; Hayat, Akhtar; Piletsky, Sergey; Piletska, Elena; Chehimi, Mohamed M; Noguer, Thierry; Rouillon, Régis

    2014-12-01

    We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. 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.

  12. Osteoconducting bioglass synthesis via sol-gel process; Biovidro osteocondutor sintetizado pelo processo sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, R.V.; Aragones, A.; Barra, G.O.M.; Salmoria, G.V.; Fredel, M.C., E-mail: rafaelavpereira@gmail.com [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-07-01

    The presence of bioglasses in scaffolds has been studied as they promote the osteoconduction in bones. The scaffolds are developed in order to induce the repair and regeneration in bone tissue. An absorbable bioglass from SiO2-CaO-P2O5 system was synthesized by sol-gel process with the intent of producing these scaffolds. Bioglass 58S was define for these work once it presents ions (Ca and P) which assist at the carbonated apatite layer formation when released. The apatite layer presents an important role at the bone regeneration and metabolism, being involved at grow and mineralization of bones. FTIR was realized to characterize the synthesized bioglass on its chemical composition, XRD to analyze the crystalline structure, solubility test to observe the weight variance and SEM to observe the particles morphology. The obtained results confirmed the production of a bioglass with the desired composition to produce osteoconducting scaffolds. (author)

  13. Absorbability of bulk sol-gel bioactive glasses

    Energy Technology Data Exchange (ETDEWEB)

    Hamadouche, M.; Meunier, A.; Blanchat, C.; Sedel, L. [Paris-7 Univ. (France). Lab. de Recherches Orthopediques; Greenspan, D.C.; Zhong, J.P.; Torre, G.P. la [US Biomaterials Corp., Alachua, FL (United States)

    2001-07-01

    Melt-derived bioactive glasses have been used with success in various clinical applications for over 10 years. Recently, particles of sol-gel derived bioactive glasses with an initial high specific area have exhibited high osteoconductive properties, but also a significant degradability. In this work, we explored the in-vivo bioactivity and degradability of bulk sol-gel derived glasses. Two sol-gel compositions (58S and 77S Bioglass) were used. Bulk 45S5 were used as a control. Both sol-gel derived demonstrated similar osteoconductive properties to 45S% Bioglass. In addition, absorbability was observed for sol-gel derived glasses after 12 weeks of implantation. Total absorption reached 40% after 52 weeks. No degradation could be measured in the case of 45S5 melt derived Bioglass. The degradation process was highly time dependent as demonstrated by regression analysis. New bone formation was found to fill in areas that had been resorbed similar to bone remodeling. New bone was found to fill in areas that had been absorbed, similar to natural bone remodeling. This absorbability can be assumed to be at least partially related to an osteoclastic resorption, as viable osteoclasts-like cells were found directly in contact with the glass surfaces. (orig.)

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

    Directory of Open Access Journals (Sweden)

    María Aymerich

    2016-08-01

    Full Text Available 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.

  15. Porphyrinosilica and metalloporphyrinosilica: hybrid organic-inorganic materials prepared by sol-gel processing

    Directory of Open Access Journals (Sweden)

    YASSUKO IAMAMOTO

    2000-03-01

    Full Text Available New materials porphyrinosilica and metalloporphyrinosilica template have been obtained by a sol-gel processing where functionalyzed porphyrins and metalloporphyrins "building blocks" were assembled into a three-dimensional silicate network. The optimized conditions for preparation of these materials are revised. The monomer precursors porphyrinopropylsilyl and metalloporphyrinopropylsilyl preparation reactions and subsequent one pot sol-gel processing with tetraethoxysilane are discussed. In the case of metalloporphyrins the nitrogen base coordinates to the central metal and acts as a template in the molecular imprinting technique. UV-visible absorption spectroscopy, thermogravimetric analysis, electron paramagnetic resonance, nuclear magnetic spectra, infrared spectra, luminescence spectra, surface area and electron spectroscopy imaging of the materials are used to characterize the prepared materials. The catalytic activities of these metalloporphyrinosilica- template are compared.

  16. Cotton Fabric Surface Modification by Sol-Gel Deposition of ZnO Thin Films

    Science.gov (United States)

    Vihodceva, S.; Kukle, S.

    2012-08-01

    One of the main tasks of research is to impact the additional value on natural textiles by adding to them ultraviolet (UV) absorption and antimicrobial protection properties with ZnO nano-level coatings. ZnO shows high absorption in the UV region of the light spectrum, in comparison with organic absorbers conventionally used in the textile industry shows no significant degradation, is stable and classified as non-toxic material. Nanosols were prepared by using the sol-gel process. In this work comparison of samples coated by nanosols with zinc acetate (Zn (CH3COO)2-2H2O) and zinc sulphate (ZnSO4) was made. Scanning electron microscopy (SEM) was used to examine the nature of the surface modification with ZnO coating by the sol-gel technique as also after exploitation of samples; energy dispersive X-ray spectroscopy was used for the analysis of elemental composition of coated fabric samples.

  17. 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.

  18. Photonic crystal patterning of luminescent sol-gel films for light extraction

    Energy Technology Data Exchange (ETDEWEB)

    Revaux, Amelie; Dantelle, Geraldine; Guillemot, Francois; Weisbuch, Claude; Boilot, Jean-Pierre; Gacoin, Thierry [Laboratoire de Physique de la Matiere Condensee, Ecole Polytechnique/CNRS UMR7643, F-91128 Palaiseau (France); Decanini, Dominique; Haghiri-Gosnet, Anne-Marie [Laboratoire de Photonique et Nanostructures, CNRS UPR20, F-91460 Marcoussis (France); Benisty, Henri, E-mail: amelie.revaux@polytechnique.edu [Laboratoire Charles Fabry de l' Institut d' Optique, CNRS, Universite Paris-Sud, Campus Polytechnique, RD 128, F-91127 Palaiseau Cedex (France)

    2011-09-07

    Structured luminescent thin films are investigated in the context of improved light extraction of phosphors for solid-state-lighting applications. Thin films composed of a sol-gel titania matrix doped with europium chelates are studied as a model system. These films, patterned with a square photonic lattice by soft nanoimprint lithography, are characterized by angle-resolved fluorescence. Modeling of this simple technique is shown to fit well the experimental data, revealing in great detail the guided modes of the film and their extraction parameters. An eightfold extraction enhancement factor of the film emission is measured. To further improve the extraction efficiency, we investigate the role of an additional low-index mesoporous silica underlayer through its influence on the guided modes of different polarizations and their interactions with the photonic crystal. Results obtained on model systems open the way towards the optimization of light-emitting devices, using a strategy of dielectric microstructure engineering using the sol-gel process.

  19. 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.

  20. Fluor-hydroxyapatite sol-gel coating on titanium substrate for hard tissue implants.

    Science.gov (United States)

    Kim, Hae-Won; Kim, Hyoun-Ee; Knowles, Jonathan C

    2004-08-01

    Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) films were deposited on a titanium substrate using a sol-gel technique. Different concentrations of F- were incorporated into the apatite structure during the sol preparation. Typical apatite structures were obtained for all coatings after dipping and subsequent heat treatment at 500 degrees C. The films obtained were uniform and dense, with a thickness of approximately 5 microm. The dissolution rate of the coating layer decreased with increasing F- incorporation within the apatite structure, which demonstrates the possibility of tailoring the solubility by a functional gradient coating of HA and FHA. The cell proliferation rate on the coating layer decreased slightly with increasing F- incorporation. The alkaline phosphatase (ALP) activity of the cells on all the HA and FHA coated samples showed much higher expression levels compared to pure Ti. This confirmed the improved activity of cell functions on the substrates with the sol-gel coating treatment.

  1. 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.

  2. 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.

  3. Sol-gel materials for optofluidics - process and applications

    DEFF Research Database (Denmark)

    Mikkelsen, Morten Bo Lindholm

    2011-01-01

    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......, continuous tumbling across the grooves called the ’tumbleweed’. Dynamical transitions between the two states cause DNA molecules to exhibit both size- and topology-dependent velocities that may be utilized for separation. By templating the porosity of sol-gel silica with sub-wavelength latex particles...

  4. Sol-Gel Synthesis and Characterization of Nanoparticles

    Directory of Open Access Journals (Sweden)

    S. Ramesh

    2013-01-01

    Full Text Available The nanoparticles have been synthesized by sol-gel technique. X-ray diffraction, scanning electron microscopy, optical absorption spectroscopy, and electron paramagnetic resonance spectroscopy were used to characterize the sample. The X-ray diffraction results indicate the formation of nanocrystalline materials in tetragonal lattice with P42/nnm space group. The identical distribution of elements were confirmed by scanning electron microscopy with energy dispersive X-ray spectrometry and X-ray mapping. Electron paramagnetic resonance lineshapes of the samples are obtained at various (13 K, 77 K, and 300 K temperatures. The isotropic lineshapes of the sample B1 are attributed to dipole-dipole interaction of Ti3+ ions. The incorporation of Al3+ ions into the sample B2–B5 the isotropic nature of the lineshapes are collapsed due to the distraction in crystal field. Optical absorption spectra results reveal the presence of Ag-TiO2 nanoparticles.

  5. /dopamine films prepared by sol-gel method

    Science.gov (United States)

    Valverde-Aguilar, G.; Prado-Prone, G.; Vergara-Aragón, P.; Garcia-Macedo, J.; Santiago, Patricia; Rendón, Luis

    2014-09-01

    Dopamine was encapsulated into nanoporous amorphous TiO2 matrix by sol-gel method under atmospheric conditions. A second sample was obtained by the addition of the crown-ether 15C5 in this previous sample. Thin films were spin-coated on glass wafers. No heat treatment was employed in both films. All films were characterized using infrared spectroscopy, high resolution transmission electronic microscopy, X-ray diffraction, optical absorption and scanning electronic microscopy. Despite the films prepared with 15C5 were no calcined, a partial crystallization was identified. Anatase and rutile nanoparticles with sizes of 4-5 nm were obtained. Photoconductivity technique was used to determine the charge transport mechanism on these films. Experimental data were fitted with straight lines at darkness and under illumination wavelengths at 320, 400, and 515 nm. It indicates an ohmic behavior. Photovoltaic and photoconductivity parameters were determined from the current density vs. the applied-electrical-field results. Amorphous film has bigger photovoltaic and photoconductive parameters than the partially crystalline film. Results observed in the present investigation prove that the nanoporous TiO2 matrix can protect the dopamine inhibiting its chemical instability. This fact modifies the optical, physical and electrical properties of the film, and is intensified when 15C5 is added.

  6. Sol gel growth of titania from electrospun polyacrylonitrile nanofibres

    Science.gov (United States)

    Hong, Youliang; Li, Domgmei; Zheng, Jian; Zou, Guangtian

    2006-04-01

    In this paper we report on the development of TiO2 surface-residing electrospun nanofibres with controllable density of TiO2 on the support fibre surface by means of an electrospinning technique and a sol-gel process. The TiO2 precursor/PAN composite nanofibres were synthesized by electrospinning a polyacrylonitrile (PAN) solution containing TiO2 precursors. Subsequently, an immersion of the electrospun composite nanofibres in deionized water led to the hydrolysis of the TiO2 precursors. SEM, TEM and XRD pattern analyses demonstrated that TiO2 was formed and resided on the nanofibre surface. On further calcining the hydrolysed nanofibres in air at 300 °C, TiO2 could be conveniently converted into anatase without essentially changing the morphology of the hydrolysed nanofibres. Furthermore, surface photovoltage spectroscopy (SPS) confirmed that the TiO2 surface-residing nanofibre nonwovens had a strong SPS response. It can be attributed that the surface residence of TiO2 permits the transfer of the photogenerated electron originating from TiO2 to ITO electrodes. Potential applications of the TiO2 surface-residing nanofibres include filters, catalysis films and environmental pollution remediation films.

  7. Advancement in corrosion resistance of AA 2024-T3 through sol-gel coatings including nanocontainers

    Directory of Open Access Journals (Sweden)

    Kartsonakis Ioannis A.

    2017-01-01

    Full Text Available The current study investigates the effect of nanocontainers incorporation into sol-gel coatings for the protection improvement of aluminium alloys 2024-T3 against corrosion. The nanocontainers were synthesized via a combination of radical polymerization process and sol-gel technique. They consist of cerium and molybdenum oxides and loaded with the anodic corrosion inhibitor 2-mercaptobenzothiazole (MBT. The preparation of the coating matrix was accomplished using (3-glycidoxypropyltrimethoxysilane as precursor. These organic modified silicate based sol-gel films were evaluated for their corrosion behaviour as well as nanomechanical properties using electrochemical and nanoindentation techniques, respectively. The results reveal that the presence of loaded nanocontainers improved the corrosion protection of the coatings; outcome that can be attributed to either the increase coherence of the coating or the simultaneously inhibition action of cerium and molybdate ions together with the corrosion inhibitor MBT. Moreover, the addition of nanocontainers empty or loaded with inhibitor amount strengthens (increase of wear resistance the coating and decreases the coefficient of friction.

  8. Functionalization of sol-gel zirconia composites with europium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Danchova, Nina; Gutzov, Stoyan [Sofia Univ. ' St Kliment Ohridski' (Bulgaria). Dept. of Physical Chemistry

    2014-02-15

    Different sol-gel strategies based on functionalization of ZrO{sub 2}:Eu microparticles with 1,10-phenanthroline (phen) and incorporation of colloidal Eu(phen){sub 2}(NO{sub 3}){sub 3} into zirconia have been used to obtain hybrid sol-gel composites with controlled optical properties. The process leads to materials with quantum yields of about 48 % monitoring the 615 nm emission line at 350 nm excitation. Excitation/luminescence spectroscopy, diffuse reflectance spectroscopy and X-ray diffraction have been used to characterize the hybrid zirconia composites. (orig.)

  9. 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 (TiO2 ) coating, zirconia with sol-gel derived zirconia (ZrO2 ) 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 TiO2 coated and ZrO2 coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO2 showed significantly lower fibroblast proliferation compared to other groups (p sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO2 coated specimens showed significantly lower cell proliferation after 12 days than TiO2 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.

  10. 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.

  11. Reversible conversion between AgCl and Ag in AgCl-doped RSiO{sub 3/2}-TiO{sub 2} films prepared by a sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Go, E-mail: gokawamura@ee.tut.ac.jp [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Tsurumi, Yuuki [Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Muto, Hiroyuki [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Sakai, Mototsugu; Inoue, Mitsuteru [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Matsuda, Atsunori [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan)

    2011-10-17

    Highlights: {center_dot} The reversible redox behavior between AgCl and Ag in RSiO{sub 3/2}-TiO{sub 2} film is studied. {center_dot} TiO{sub 2} component induces Cl to remain in the film after conversion of AgCl to Ag. {center_dot} The survival of Cl is essential for reconversion of Ag to AgCl. {center_dot} The film shows potential to be applied as rewritable holographic material. - Abstract: The reversible redox behavior exhibited by AgCl-doped organosilsesquioxane-titania gel films is studied. Films prepared by the sol-gel method show reversible color changes with blue laser irradiation and subsequent heat treatment, which is based on the formation of Ag and AgCl nanoparticles, respectively. Two-beam interference exposure experiments reveal that the films have potential to be applied as rewritable holographic materials. A large titania content is essential for the conversion of Ag to AgCl because it induces the Cl to remain near the Ag nanoparticles during blue laser irradiation, allowing the Cl to react with neighboring Ag nanoparticles to reform AgCl upon subsequent heat treatment.

  12. Preparation of Glass Plate-Supported Nanostructure ZnO Thin Film Deposited by Sol-Gel Spin-Coating Technique and Its Photocatalytic Degradation to Monoazo Textile Dye

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Habibi

    2008-01-01

    Full Text Available Glass plate-supported nanostructure ZnO thin films were deposited by sol-gel spin coating. Films were preheated at 275∘C for 10 minutes and annealed at 350, 450, and 550∘C for 80 minutes. The ZnO thin films were transparent ca 80–90% in visible range and revealed that absorption edges at about 370 nm. The c-axis orientation improves and the grain size increases which was indicated by an increase in intensity of the (002 peak at 34.4∘ in XRD corresponding to the hexagonal ZnO crystal. The photocatalytic degradation of X6G an anionic monoazo dye, in aqueous solutions, was investigated and the effects of some operational parameters such as the number of layer and reusability of ZnO nanostructure thin film were examined. The results showed that the five-layer coated glass surfaces have a very high photocatalytic performance.

  13. Sol-Gel Synthesis and Characterization of Ba1-xGdxTiO3+δ Thin Films on SiO2/Si Substrates Using Spin-Coating Technique

    Directory of Open Access Journals (Sweden)

    Yen Chin TEH

    2017-02-01

    Full Text Available Ba1-xGdxTiO3+δ, at x = 0, 0.05, 0.1, 0.15, 0.2, (BGT thin films have been fabricated on SiO2/Si substrate using Sol-Gel method. The microstructure and surface morphology of the fabricated films have been investigated using X-ray diffraction (XRD and atomic force microscopy (AFM. The XRD results show that the fabricated films are crystalline with perovskite structure. There is a shifting of the preferred peak at 31.5o to a higher angle as the doping ratio increases suggesting a distortion lattice exists in the films, which could be due to the substitution of Gd3+ ions into Ba-site. The decreasing of lattice constants confirms the substitution of Gd3+ in BaTiO3 lattice structure. The microstrain and dislocation density are found to be increased with the increase of Gd3+ doping, which attributed to the reduction of lattice volume that due to the ionic size mismatch effect. The AFM results show decreasing trend in both average grain size and roughness parameters. Therefore, the microstructure and surface morphology of BGT samples is strongly dependent on the Gd3+ doping concentration that mainly due to the difference ionic radius substitution.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13954

  14. Femtosecond double proton transfer dynamics in [2,2'-bipyridyl]-3,3'-diol in sol-gel glasses

    NARCIS (Netherlands)

    Prosposito, P.; Marks, D.R.A.; Zhang, H.; Glasbeek, M.

    1998-01-01

    Abstract: Intramolecular excited state double proton-transfer dynamics has been studied for [2,2'-bipyridyl]-3,3'-diol (BP(OH)2) in sol-gel glass. By means of the femtosecond fluorescence up-conversion technique, the spectral dependence of the fluorescence transients obtained for BP(OH)2 in a few

  15. TEM study of indium and gallium nitride nanocrystals in silica gasses obtained by the sol-gel method.

    Science.gov (United States)

    Krajczyk, L; Jabłoński, J M; Nyk, M; Strek, W; Misiewicz, J

    2006-09-01

    GaN and InN nanocrystals in silica glasses prepared by the sol-gel method were studied by transmission electron microscopy techniques. Morphology, structure and phase composition of silica gel containing Ga or In as function of the calcination and nitridation temperature were investigated.

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Balbay, Senay; Acıkgoz, Caglayan

    2017-11-01

    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.

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-01-01

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

  1. Investigation of Sol-Gel coatings exposed in the condenser at Fynsvaerket. Part 3

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, M. [DTU Mekanik, Kgs. Lyngby (Denmark); Vilhelmsen, T. [Vattenfall Heat Nordic, Copenhagen (Denmark)

    2009-05-15

    The Danish Technological Institute (DTI) has developed a technique using Hybrid Solgel nanotechnology to produce coatings which can change the surface characteristics of various components. It is the purpose of this project to investigate where such coatings can be utilised in the power generating industry with respect to fouling and corrosion resistance. The initial results with sol-gel coatings on the condenser tubes at Fysnvaerket showed that due to the presence of corrosion products on the unexposed tubes which influences the adherence and protectiveness of coatings applied, the effect of sol-gel coatings was difficult to assess. Further specimens were tested where the outer surface had been mechanically cleaned by sand blasting or by grinding and polishing. The results of 3 months exposure in the condenser plate at the outlet (hottest part of condenser) has been reported. Many coatings showed the anti-fouling effect, however closer inspection with scanning electron microscopy revealed cracks in the coating and oxide below the coating indicating the coating was permeable to corrosive species. The specimens described in this report are from the cold side of the condenser after 1 year's exposure. Due to lack of time, the assessment is based on visual assessment and light optical microscopy. Two different sol-gel coatings have been applied to brass and titanium condenser tubes about 10 cm in length. Based on the experience from previous exposures, the surface of the condenser tubes was mechanically cleaned before coating with the sol-gel components. One set was sandblasted and the other set was grinded to a polished finish using sandpaper. The specimens grinded and polished were exposed tubes that had been removed from the condenser. Investigations of unexposed cleaned condenser tubes with and without sol-gel have been reported previously. Before application of the coatings, the tubes were mechanically cleaned either by sandblasting or by grinding to a

  2. 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.

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

    Science.gov (United States)

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

    1994-10-01

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

  4. Covalent immobilization of carbohydrates on sol-gel-coated microplates.

    Science.gov (United States)

    Zou, Lan; Pang, Hei-Leung; Chan, Pak-Ho; Huang, Zhi-Shu; Gu, Lian-Quan; Wong, Kwok-Yin

    2008-09-01

    Carbohydrate microarrays have attracted increasing attention in recent years because of their ability to monitor biologically important protein-carbohydrate interactions in a high-throughput manner. Here we have developed an effective approach to immobilizing intact carbohydrates directly on polystyrene microtiter plates coated with amine-functionalized sol-gel monolayers. Lectin binding was monitored by fluorescence spectroscopy using these covalent arrays of carbohydrates that contained six mono- and di-saccharides on the microplates. In addition, binding affinities of lectin to carbohydrates were also quantitatively analyzed by determining IC(50) values of lectin-specific antibody with these arrays. Our results indicate that microplate-based carbohydrate arrays can be efficiently fabricated by covalent immobilization of intact carbohydrates on sol-gel-coated microplates. The microplate-based carbohydrate arrays can be applied for screening of protein-carbohydrate interactions in a high-throughput manner.

  5. Sol-Gel Thin Films for Plasmonic Gas Sensors

    Directory of Open Access Journals (Sweden)

    Enrico Della Gaspera

    2015-07-01

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

  6. Synthesis and Conductometric Property of Sol-Gel-Derived ZnO/PVP Nano Hybrid Films

    Science.gov (United States)

    Ilegbusi, Olusegun J.; Trakhtenberg, Leonid

    2013-03-01

    ZnO nanoparticles immobilized in polyvinylpyrrolidone (PVP) were prepared using sol-gel dip-coating technique with varying Zn2+/PVP ratios. The films were characterized using atomic force microscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy for chemical analysis. The size and concentration of ZnO particles decreased as the Zn/PVP ratio decreased. Under low Zn2+/PVP molar ratios, ZnO particles were clearly well separated and capped in the PVP polymer matrix. Electrical resistivity of 108 Ω cm was achieved under these deposition conditions.

  7. Effect of preparation methods on the properties of titania nanoparticles: solvothermal versus sol-gel

    Science.gov (United States)

    Dastan, Davoud

    2017-11-01

    Titania (TiO2) nanoparticles (NP's) have been prepared by solvothermal and sol-gel techniques using different surfactants such as acetic acid (AA), oleylamine (OM), and AA + OM. The solution was thermally treated at growth temperature 180 °C in solvothermal method. TiO2 powder, prepared using both methods, was subjected to post heat treatment at 550 and 950 °C. The effect of surfactants on the morphology of TiO2 NP's was studied by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The structural and thermal properties of titania NP's are investigated by means of X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and differential scanning calorimetry (TGA/DSC). TEM and FESEM images illustrated various shapes of titania NP's such as irregular spherical, rounded rectangular, truncated rhombic, oval, and rod-like structure in presence of different surfactants. Moreover, TiO2 particles prepared by sol-gel method were almost 40 times greater than those prepared by solvothermal method. In addition to the improvement in the crystallinity, thermal stability has been enhanced due to consolidation of individual particles at higher annealing temperature in solvothermal technique. Furthermore, a reduction in the degradation temperature and phase transformation of TiO2 NP's were conspicuously corroborated after post-heat treatment.

  8. 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

  9. Sol-gel synthesis and characterization of undoped and Al-doped ZnO thin films for memristive application

    Directory of Open Access Journals (Sweden)

    Dawit G. Ayana

    2016-11-01

    Full Text Available The Sol-gel route is a versatile method to fabricate multi-layer, dense and homogeneous ZnO thin films with a controlled thickness and defects for a memristive application. In this work, sol-gel derived multi-layer undoped and Al-doped ZnO thin films were prepared by a spin-coating technique on SiO2/Ti/Pt and silica glass substrates. The effect of both Al doping and curing conditions on the structural and morphological features of ZnO films was investigated by complementary techniques, including electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction analysis. Electrical measurements were performed on SiO2/Ti/Pt/ZnO/Pt(dishes and SiO2/Ti/Pt/ZnO(Al/Pt(dishes fabricated memristive cells and preliminary current-voltage curves were acquired.

  10. 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

  11. Rare-earth (Nd3+, Er3+, and Yb3+)-doped aluminium phosphate sol-gel films

    Science.gov (United States)

    He, Qing; Lafreniere, Sylvain; Najafi, S. Iraj; Honkanen, Seppo

    1993-04-01

    In this paper, we report on fabrication process of ordinary and rare-earth-doped aluminum phosphate sol-gel films and their physical and optical properties. The gel films are transparent, hard and of good optical quality as glass. High doping of rare-earths (Nd3+, Er3+ and Yb3+) are realized in films with this technique. This type of doped films offer potential benefits for applications in the field of active integrated optics devices for optical telecommunication systems.

  12. The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

    Directory of Open Access Journals (Sweden)

    Ales Styskalik

    2017-05-01

    Full Text Available This review is devoted to non-hydrolytic sol-gel chemistry. During the last 25 years, non-hydrolytic sol-gel (NHSG techniques were found to be attractive and versatile methods for the preparation of oxide materials. Compared to conventional hydrolytic approaches, the NHSG route allows reaction control at the atomic scale resulting in homogeneous and well defined products. Due to these features and the ability to design specific materials, the products of NHSG reactions have been used in many fields of application. The aim of this review is to present an overview of NHSG research in recent years with an emphasis on the syntheses of mixed oxides, silicates and phosphates. The first part of the review highlights well known condensation reactions with some deeper insights into their mechanism and also presents novel condensation reactions established in NHSG chemistry in recent years. In the second section we discuss porosity control and novel compositions of selected materials. In the last part, the applications of NHSG derived materials as heterogeneous catalysts and supports, luminescent materials and electrode materials in Li-ion batteries are described.

  13. Sol-gel derived zinc oxide films alloyed with cobalt and aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mamta [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi 110 021 (India); Mehra, R.M., E-mail: rammehra2003@yahoo.co [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi 110 021 (India)

    2010-05-03

    ZnO films codoped with 5 at.% Co and 1 at.% Al were prepared by sol-gel technique on corning glass and silicon substrates with precursor sols of different pH values. The pH was varied from 5.4 to 11 by adding varying amounts of monoethanolamine to the sol. Since pH plays an important role in controlling the properties of films, we discuss in detail the effect of pH value on the structural, morphological and optical properties of the grown films. X-ray diffraction and atomic force microscopy images reveal that the size of crystallites increases with pH of the sol. The variation of pH in the reaction system influences the density of homogeneous nucleation and the crystal growth along the c-axis. High quality Co and Al codoped ZnO films annealed at 600 {sup o}C have been obtained using a sol with pH = 9. These sol-gel derived films find their suitability to be used as dilute magnetic semiconductors.

  14. Characterizations of maghemite thin films prepared by a sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lau, L. N., E-mail: lau7798@gmail.com; Ibrahim, N. B., E-mail: baayah@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor. Malaysia (Malaysia)

    2015-09-25

    Iron is one of the abundant elements of Mother Nature and its compound, iron oxide is an interesting material to study since its discovery in the form of magnetite. It can exist in many phases such as hematite and maghemite, this unique nature has put it as a potential candidate in various applications. The aim of this work is to study the influence of different precursor concentrations on the microstructural and magnetic properties of iron oxide thin film. All samples were prepared via the sol-gel method followed by a spin coating technique on quartz substrates. Iron oxide films were confirmed as maghemite phase from X-ray diffraction patterns. The film morphology was examined by a field emission scanning electron microscope and it showed non-systematic value of average grain size and film thickness throughout the study. Hysteresis loop further confirmed that maghemite is a magnetic material when it was characterized by a vibrating sample magnetometer. The coercivity did not show any correlation with molarity. Nevertheless, it increased as the precursor concentration of the film increased due to the domain behaviour. In conclusion, maghemite thin films were successfully synthesized by the sol-gel method with different precursor concentrations in this work.

  15. Synthesis of zinc oxide thin films prepared by sol-gel for specific bioactivity

    Science.gov (United States)

    Adam, Tijjani; Basri, B.; Dhahi, Th. S.; Mohammed, Mohammed; Hashim, U.; Noriman, N. Z.; Dahham, Omar S.

    2017-09-01

    Zinc oxide (ZnO) thin films this device to used for many application like chemical sensor, biosensor, solar energy, etc but my project to use for bioactivity(biosensor). Zinc oxide (ZnO) thin films have been grown using sol-gel technique. Characterization was done using Scanning Electron Microscope (SEM), Energy Dispersive X-ray(EDX) and Electrical Measurement(I-V). ZnO thin film was successfully synthesized using low cost sol-gel spin coating method. The coupling of DNA probe to ZnO thin film supports modified with carboxylic acid (COOH) is certainly the best practical method to make DNA immobilization and it does not require any coupling agent which could be a source of variability during the spotting with an automatic device. So, selected this coupling procedure for further experiments. The sensor was tested with initial trial with low concentrated DNA and able to detect detection of the disease effectively. Silicon-on-insulator (SOI) wafer device with ZnO can detect at different concentration in order to valid the device capabilities for detecting development. The lowest concentration 1 µM HPV DNA probe can detect is 0.1 nM HPV target DNA.

  16. Dialkylenecarbonate-Bridged Polysilsesquioxanes. Hybrid Organic Sol-Gels with a Thermally Labile Bridging Group

    Energy Technology Data Exchange (ETDEWEB)

    Loy, D.A.; Beach, J.V.; Baugher, B.M.; Assink, R.A.; Shea, K.J.; Tran, J.; Small, J.H.

    1999-04-21

    In this paper, we introduce a new approach for altering the properties of bridged polysilsesquioxane xerogels using post-processing modification of the polymeric network. The bridging organic group contains latent functionalities that can be liberated thermally, photochemically, or by chemical means after the gel has been processed to a xerogel. These modifications can produce changes in density, volubility, porosity, and or chemical properties of the material. Since every monomer possesses two latent functional groups, the technique allows for the introduction of high levels of functionality in hybrid organic-inorganic materials. Dialkylenecarbonate-bridged polysilsesquioxane gels were prepared by the sol-gel polymerization of bis(triethoxysilylpropyl)carbonate (1) and bis(triethoxysilylisobutyl)-carbonate (2). Thermal treatment of the resulting non-porous xerogels and aerogels at 300-350 C resulted in quantitative decarboxylation of the dialkylenecarbonate bridging groups to give new hydroxyalkyl and olefinic substituted polysilsesquioxane monolithic xerogels and aerogels that can not be directly prepared through direct sol-gel polymerization of organotrialkoxysilanes.

  17. Sol-Gel Synthesis of Ceria-Based Electrolytes and Perovskite-Type Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Pinol, S.; Calleja, A.; Capdevila, X. G.; Najib, M.; Espiell, F.

    2002-06-01

    We have successfully prepared electrolytes of Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9} (SDC) and Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9} (GDC) and cathodes of La{sub 1-x}Sr{sub x}CoO{sub 3} (LSCO) and La{sub 1-x}Sr{sub x}MnO{sub 3} (LSMO), useful for SOFCs, by the acrylamide sol-gel method. This method consists in the preparation of a solution from the elemental oxides and carbonates followed by a gellification with acrylamide monomer. Then, the combustion of the organic molecules is initiated, obtaining ultra fine calcined powders of the above-mentioned compounds. In this way, we have obtained high purity powders of SDC, GDC, LSCO and LSMO as confirmed by X-ray diffraction powder analysis. On the other hand, we have also studied the preparation of the same products by the solid-state reaction technique for comparison purposes. However, it was not possible to obtain pure LSCO by this ceramic method. We have observed that the optimal synthesis temperature is lower for the sol-gel samples and the final purity of the products is higher. (author)

  18. Third-order nonlinear optical properties of metal dithiolene- and phthalocyanine-doped sol-gel materials

    Science.gov (United States)

    Gall, Gavin J.; King, Terence A.; Oliver, Stephen N.; Capozzi, Carol A.; Seddon, Angela B.; Hill, Callum A. S.; Underhill, Allan E.

    1994-10-01

    Recent studies on metal dithiolene complexes in solution and PMMA have shown this range of materials to exhibit high third-order nonlinear optical coefficients, (Chi) 3, and excellent figures of merit. Phthalocyanine dyes have been shown to exhibit optical limiting due to the nonlinear effect of reverse saturable absorption. We report here on the third-order nonlinear optical characterization of several metal dithiolene and phthalocyanine compounds doped in sol-gel derived materials. These hosts provide a physically and chemically stable environment for the nonlinear compounds, and offer the potential of high levels of doping. The dithiolene and phthalocyanine compounds were incorporated into partially densified sol-gel silica glass (xerogels) by the post-doping technique, and into the hybrid organic-inorganic materials at the sol-stage. To obtain optical quality surfaces on the porous xerogel, a unique polishing technique has been developed. Picosecond and nanosecond pulsed laser studies of nonlinear refraction and absorption are presented, together with laser damage and micro-hardness measurements. For the dithiolenes, concentrations of the order of 1018 molecules/cm3 for both the hybrid material and the xerogel were studied using the degenerate four wave mixing (DFWM) technique. (Chi) 3 values up to 1.4 X 10-19 m2/V2 (equivalent to 1.0 X 10-11 esu) were observed in the sol-gel host.

  19. STUDY ON SYNTHESIS AND EVOLUTION OF NANOCRYSTALLINE Mg4Ta2O9 BY AQUEOUS SOL-GEL PROCESS

    Science.gov (United States)

    Wu, H. T.; Yang, C. H.; Wu, W. B.; Yue, Y. L.

    2012-06-01

    Nanosized and highly reactive Mg4Ta2O9 were successfully synthesized by aqueous sol-gel method compared with conventional solid-state method. Ta-Mg-citric acid solution was first formed and then evaporated resulting in a dry gel for calcination in the temperature ranging from 600°C to 800°C for crystallization in oxygen atmosphere. The crystallization process from the gel to crystalline Mg4Ta2O9 was identified by thermal analysis and phase evolution of powders was studied using X-ray diffraction (XRD) technique during calcinations. Particle size and morphology were examined by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HR-SEM). The results revealed that sol-gel process showed great advantages over conventional solid-state method and Mg4Ta2O9 nanopowders with the size of 20-30 nm were obtained at 800°C.

  20. Review on Development of Ceramic Membrane From Sol-Gel Route: Parameters Affecting Characteristics of the Membrane

    Directory of Open Access Journals (Sweden)

    M. R. Othman and H. Mukhtar

    2012-08-01

    Full Text Available The importance of laboratory scale ceramic membrane preparation using sol-gel technique with pore sizes in the range of 1-10nm is reviewed. Parameters affecting the characteristics of membrane during membrane development are highlighted and discussed in detail. Experimental results from literatures have shown that the correct amount of acid, water, PVA, appropriate membrane thickness, proper control of drying rate, and appropriate temperature profile selection during sintering process are necessary in order to acquire sufficient strength and reduce the formation of crack in the membrane. The different temperature setting during sintering process also influences the size of pore formed.Key Words: Sol-Gel, Inorganic Membrane, Ceramic Membrane, Gas Permeation, Sintering, Sol Properties, Membrane Morphologies, Pore Size Distribution.

  1. Sol - Gel synthesis and characterization of magnesium peroxide nanoparticles

    Science.gov (United States)

    Jaison, J.; Ashok raja, C.; Balakumar, S.; Chan, Y. S.

    2015-04-01

    Magnesium peroxide is an excellent source of oxygen in agriculture applications, for instance it is used in waste management as a material for soil bioremediation to remove contaminants from polluted underground water, biological wastes treatment to break down hydrocarbon, etc. In the present study, sol-gel synthesis of magnesium peroxide (MgO2) nanoparticles is reported. Magnesium peroxide is odourless; fine peroxide which releases oxygen when reacts with water. During the sol-gel synthesis, the magnesium malonate intermediate is formed which was then calcinated to obtain MgO2 nanoparticles. The synthesized nanoparticles were characterized using Thermo gravimetric -Differential Thermal Analysis (TG- DTA), X-Ray Diffraction studies (XRD) and High Resolution Transmission Electron Microscope (HRTEM). Our study provides a clear insight that the formation of magnesium malonate during the synthesis was due to the reaction between magnesium acetate, oxalic acid and ethanol. In our study, we can conclude that the calcination temperature has a strong influence on particle size, morphology, monodispersity and the chemistry of the particles.

  2. Observation and manipulation of magnetic domains in sol gel derived thin films of spinel ferrites

    Science.gov (United States)

    Datar, Ashwini A.; Mathe, Vikas L.

    2017-12-01

    Thin films of spinel ferrites, namely zinc substituted nickel, cobalt ferrite, and manganese substituted cobalt ferrite, were synthesized using sol-gel derived spin-coating techniques. The films were characterized using x-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy techniques for the analysis of structural, morphological and vibrational band transition properties, which confirm the spinel phase formation of the films. The magnetic force microscopy (MFM) technique was used to observe the magnetic domain structure present in the synthesized films. Further, the films were subjected to an external DC magnetic field of 2 kG to orient the magnetic domains and analyzed using an ex situ MFM technique.

  3. Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

    Science.gov (United States)

    Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

    2016-12-01

    Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

  4. Sol-gel-cum-hydrothermal synthesis of mesoporous Co-Fe@Al2O3 ...

    Indian Academy of Sciences (India)

    A combined sol-gel-cum-hydrothermal method has been employed to synthesize novel monometal- lic (Mn, Fe, Co) and bimetallic (Co-Fe, .... Mesoporous Al2O3 was synthesized by sol-gel method. Cetyltrimethylammonium bromide ... TEOS silica source was added to the mixture and stirred for. 2 h (solution A) to obtain ...

  5. 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.

  6. 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.

  7. Routes to extrinsic and intrinsic self-healing corrosion protective sol-gel coatings: a review

    Science.gov (United States)

    Abdolah Zadeh, M.; van der Zwaag, S.; Garcia, S. J.

    2013-06-01

    Sol-gel pre-treatments and coatings are an important class of passive protective coatings, which can effectively prevent corrosion of various metallic substrates through adhesion improvement and barrier protection. Recently, sol-gel chemistry has been proposed as an appropriate method for implementation of self-healing functionality in coatings via extrinsic concepts. In this review we will analyze the most relevant existing works on self-healing sol-gel coatings, including new work done in the direction of implementing intrinsic healing capabilities to sol-gels. The development of active sol-gel coatings is due to the broad chemical versatility of precursors and low processing temperature of this type of chemistry.

  8. Synthesis and optical characterization of C-SiO2 and C-NiO sol-gel composite films for use as selective solar absorbers

    CSIR Research Space (South Africa)

    Makiwa, G

    2008-08-01

    Full Text Available The authors present a cheaper and environmentally friendly method to fabricate efficient spectrally selective solar absorber materials. The sol-gel technique was used to fabricate carbon-silica (C-SiO2) and carbon-nickel oxide (C-NiO) composite...

  9. Biosorption of uranium and copper by Bacillus Sphaericus JG-A12 cells, spores and S-layer proteins embedded in sol-gel ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Raff, J.; Soltmann, U.; Boettcher, H. [Arbeitsgruppe Funktionelle Schichten, GMBU e.V., Dresden (Germany); Matys, S.; Pompe, W. [Inst. fuer Materialwissenschaft, Technische Univ. Dresden (Germany); Selenska-Pobell, S.

    2002-05-01

    Vegetative cells, spores and stabilized S-layer sheets of B. sphaericus JG-A12 were embedded in SiO{sub 2} bulk particles using sol-gel techniques. In sorption experiments the metal binding capacity of the free biocomponents and the corresponding biological ceramics were compared. (orig.)

  10. Identification of TiO2 clusters present during synthesis of sol-gel derived TiO2 nano-particles

    DEFF Research Database (Denmark)

    Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    Synthesis of titanium dioxide nanoparticles with controlled size distribution and morphology are of great interest for many applications i.e. photocatalysis and dye sensitized solar cells (DSSC). The sol-gel method has some advantages over other preparation techniques in the many parameters, which...

  11. Sol-gel transition of organogels observed by terahertz spectroscopy

    Science.gov (United States)

    Hoshina, Hiromichi; Ozaki, Atsumi; Itagaki, Yusuke; Yajima, Setsuko; Suzuki, Hal; Ishii, Shinya; Ishida, Misaki; Uchiyama, Tetsuji; Kimura, Keiichi; Otani, Chiko

    2014-07-01

    Terahertz (THz) absorption spectra of organogels consisting of (1R,2R)-1,2-bis(dodecanoylamino)cyclohexane/2-nitrophenyl octyl ether (RR-BDC/NPOE) and RR-BDC/n-dodecane were measured by Fourier-transform far-infrared (FT-FIR) spectroscopy. The vibrational peaks of the gels were observed at the same frequencies as those of the pure gelator, suggesting that the intermolecular structure around the Nsbnd H⋯Odbnd C hydrogen bond is maintained in the gel phase. Temperature-dependent spectroscopy showed a drastic spectral change at the sol-gel transition temperature, in which the vibrational peak at 3.5 THz disappears and a new peak appears at 2.9 THz. The change in THz vibrational frequency is indicative of the structural collapse of the hydrogen-bonded fibrous architecture in the sol phase.

  12. Mayenite Synthesized Using the Citrate Sol-Gel Method

    Energy Technology Data Exchange (ETDEWEB)

    Ude, Sabina N [ORNL; Rawn, Claudia J [ORNL; Meisner, Roberta A [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Kirkham, Melanie J [ORNL; Jones, Gregory L. [University of Tennessee, Knoxville (UTK); Payzant, E Andrew [ORNL

    2014-01-01

    A citrate sol-gel method has been used to synthesize mayenite (Ca12Al14O33). X-ray powder diffraction data show that the samples synthesized using the citrate sol-gel method contained CaAl2O4 and CaCO3 along with mayenite when fired ex-situ in air at 800 C but were single phase when fired at 900 C and above. Using high temperature x-ray diffraction, data collected in-situ in air at temperatures of 600 C and below showed only amorphous content; however, data collected at higher temperatures indicated the first phase to crystallize is CaCO3. High temperature x-ray diffraction data collected in 4% H2/96% N2 does not show the presence of CaCO3, and Ca12Al14O33 starts to form around 850 C. In comparison, x-ray powder diffraction data collected ex-situ on samples synthesized using traditional solid-state synthesis shows that single phase was not reached until samples were fired at 1350 C. DTA/TGA data collected either in a nitrogen environment or air on samples synthesized using the citrate gel method suggest the complete decomposition of metastable phases and the formation of mayenite at 900 C, although the phase evolution is very different depending on the environment. Brunauer-Emmett-Teller (BET) measurements showed a slightly higher surface area of 7.4 0.1 m2/g in the citrate gel synthesized samples compared to solid-state synthesized sample with a surface area of 1.61 0.02 m2/g. SEM images show a larger particle size for samples synthesized using the solid-state method compared to those synthesized using the citrate gel method.

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

    Science.gov (United States)

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

    2006-11-16

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

  14. Sol-gel TiO2 colloidal suspensions and nanostructured thin films: structural and biological assessments

    Science.gov (United States)

    Quartapelle Procopio, Elsa; Colombo, Valentina; Santo, Nadia; Sironi, Angelo; Lenardi, Cristina; Maggioni, Daniela

    2018-02-01

    The role of substrate topography in phenotype expression of in vitro cultured cells has been widely assessed. However, the production of the nanostructured interface via the deposition of sol-gel synthesized nanoparticles (NPs) has not yet been fully exploited. This is also evidenced by the limited number of studies correlating the morphological, structural and chemical properties of the grown thin films with those of the sol-gel ‘brick’ within the framework of the bottom-up approach. Our work intends to go beyond this drawback presenting an accurate investigation of sol-gel TiO2 NPs shaped as spheres and rods. They have been fully characterized by complementary analytical techniques both suspended in apolar solvents, by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR) and after deposition on substrates (solid state configuration) by transmission electron microscopy (TEM) and powder x-ray diffraction (PXRD). In the case of suspended anisotropic rods, the experimental DLS data, analyzed by the Tirado-Garcia de la Torre model, present the following ranges of dimensions: 4–5 nm diameter (∅) and 11–15 nm length (L). These results are in good agreement with that obtained by the two solid state techniques, namely 3.8(9) nm ∅ and 13.8(2.5) nm L from TEM and 5.6(1) ∅ and 13.3(1) nm L from PXRD data. To prove the suitability of the supported sol-gel NPs for biological issues, spheres and rods have been separately deposited on coverslips. The cell response has been ascertained by evaluating the adhesion of the epithelial cell line Madin–Darby canine kidney. The cellular analysis showed that titania films promote cell adhesion as well clustering organization, which is a distinguishing feature of this type of cell line. Thus, the use of nanostructured substrates via sol-gel could be considered a good candidate for cell culture with the further advantages of likely scalability and interfaceability with many different materials usable as

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

    Science.gov (United States)

    Barhoum, Moussa

    Single molecule trajectories of 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbo - cyanine perchlorate (DiI) fluorophores diffusing on planar supported 1,2-dimyristoyl-snglycero- 3-phosphocholine (DMPC) lipid bilayers imaged through total internal reflection fluorescence (TIRF) microscopy at different temperatures are investigated. The spatial resolution limit for detecting molecular motion is evaluated by characterizing the apparent motion which arises from the limited signal-to-noise ratio (S/N) of imaged and simulated stationary DiI molecules. Statistical criteria for reliably distinguishing molecular motion from stationary molecules using F-test statistics, including the computation of local signal-to-noise ratios are then established and used for reliably detecting subdiffraction motion of DiI molecules on DMPC. The same single molecule tracking concept is used in investigating the temperature dependence of subdiffraction diffusional confinement of single Rhodamine 6G molecules in polymer brushes of poly (N-isopropylacrylamide), pNIPAAm, above and below its lower critical solution temperature (LCST) of 32°C. Reliably distinguishing subdiffraction molecular motion from stationary events is crucial in validating the application of single molecule tracking experiment in probing nanometersized hydrophobic environments of polymer structure. A versatile and rapid sol-gel technique for the fabrication of high quality one-dimensional photonic bandgap materials was developed. Silica/titania multilayer materials are fabricated by a sol-gel chemistry route combined with dip-coating onto planar or curved substrate. A shock-cooling step immediately following the thin film heat-treatment process is introduced. The versatility of this sol-gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties. Measured optical properties show good agreement with theoretical simulations confirming the high quality of these sol-gel

  16. Sol-gel synthesis and characterization of mesoporous iron-titanium mixed oxide for catalytic application

    Energy Technology Data Exchange (ETDEWEB)

    Parida, K.M., E-mail: paridakulamani@yahoo.com [Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar 751013, Orissa (India); Pradhan, Gajendra Kumar [Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar 751013, Orissa (India)

    2010-10-01

    A mixed phase of mesoporous iron-titanium mixed oxide (ITMO) has been successfully synthesized by simple sol-gel technique by taking iron (II) sulphate and Ti-isopropoxide as the precursors and sodium dodecyl sulphate (SDS) as the surfactant. The prepared catalysts were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-vis spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), N{sub 2} adsorption-desorptions isotherm, temperature programmed desorption (TPD) and gas chromatography (GC). Low-angle XRD (LAXRD) as well as surface area analysis confirms the mesoporosity nature of the catalysts. The phase and crystallinity were revealed by XRD study. The crystallinity of the catalysts increased with increase in calcinations temperature. Catalysts screening were performed for oxidation of cyclohexane to cyclohexanol and cyclohexanone.

  17. Photocatalytic and antibacterial activity of ZnO powders prepared via sol-gel method

    Directory of Open Access Journals (Sweden)

    Weerachai Sangchay

    2016-02-01

    Full Text Available We report on synthesis of ZnO powders via sol-gel method. The prepared powders were calcined at the temperature of 300, 500 and 700°C for 1 h with the heating rate of 10°C/min. The microstructures of the fabricated powders were characterized by SEM and XRD techniques, and the results show that all samples were the agglomeration and spherical shape and reveal only the wurtzite phase. The photocatalytic activities of the powders were also tested via the degradation of methylene blue (MB solution under UV irradiation. Finally, antibacterial activity efficiency was evaluated by the inactivation of E. coli. It was observed that higher calcined at the temperature gives better photocatalytic and antibacterial activity. With the highest calcined at the temperature investigated in this experiment (T700 condition the powders show photocatalytic and antibacterial activities of 80.06 and 99.00%, respectively.

  18. 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 .

  19. In vitro characterization of polyvinyl alcohol assisted hydroxyapatite derived by sol-gel method.

    Science.gov (United States)

    Kaygili, Omer; Keser, Serhat; Al Orainy, R H; Ates, Tankut; Yakuphanoglu, Fahrettin

    2014-02-01

    The synthesis and characterization of sol-gel derived hydroxyapatite (HAp) were investigated with the effects of the addition of polyvinyl alcohol (PVA) to the structural and material in vitro behavior. All samples were soaked in simulated body fluid (SBF) for 14 and 28 days. The characterization of bioceramics before and after immersing in SBF was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. After the simulated body fluid period, the crystal structure and phase of HAp samples did not change significantly. The characteristic bands of hydroxyl, phosphate and carbonate groups were detected. HAp exhibited a thermal stability of room temperature to 1000 °C. The surface morphologies of the samples show an evident change with the soaking period in SBF. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Rajyaguru, Bhargav; Gadani, Keval; Kansara, S. B.; Pandya, D. D.; Shah, N. A.; Solanki, P. S., E-mail: piyush.physics@gmail.com [Department of Physics, Saurashtra University, Rajkot – 360 005 (India); Rathod, K. N.; Solanki, Sapana [Department of Physics, Saurashtra University, Rajkot – 360 005 (India); V.V.P. Engineering College, Gujarat Technological University, Rajkot – 360 005 (India)

    2016-05-06

    In this communication, we report the results of the studies on structural properties and gas sensing behavior of nanostructured ZnO grown using acetone precursor based modified sol-gel technique. Final product of ZnO was sintered at different temperatures to vary the crystallite size while their structural properties have been studied using X-ray diffraction (XRD) measurement performed at room temperature. XRD results suggest the single phasic nature of all the samples and crystallite size increases from 11.53 to 20.96 nm with increase in sintering temperature. Gas sensing behavior has been studied for acetone gas which indicates that lower sintered samples are more capable to sense the acetone gas and related mechanism has been discussed in the light of crystallite size, crystal boundary density, defect mechanism and possible chemical reaction between gas traces and various oxygen species.

  1. Synthesis, Consolidation and Characterization of Sol-gel Derived Tantalum-Tungsten Oxide Thermite Composites

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, O [Univ. of California, Davis, CA (United States)

    2010-06-01

    Energetic composite powders consisting of sol-gel (SG) derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the SG derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The SG derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO3) energetic composite was consolidated to a density of 9.17 g·cm-3 or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.

  2. A utilização de materiais obtidos pelo processo de sol-gel na construção de biossensores The utilization of materials obtained by the sol-gel process in biosensors construction

    Directory of Open Access Journals (Sweden)

    Antonio A. S. Alfaya

    2002-09-01

    Full Text Available The use of sol-gel materials to develop new biosensors has received great attention due to its characteristics and versatility of sol-gel process. An overview is presented of the state-of-the-art of electrochemical biosensors employing sol-gel materials. Low-temperature, porous sol-gel ceramics represent a new class for the immobilization of biomolecules. The rational design of sol-gel sensing materials, based on the judicious choice of the starting alkoxide, encapsulated reagents, and preparation conditions, allows tailoring of material properties in a wide range, and offers great potential for the development of electrochemical biosensors.

  3. 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%.

  4. 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-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%.

  5. 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.

  6. SINTESIS LAPIS TIPIS BERBASIS NANOPARTIKEL TITANIA TERMODIFIKASI SILIKA SECARA SOL-GEL SEBAGAI BAHAN ANTIFOGGING

    Directory of Open Access Journals (Sweden)

    L.V. Rissa

    2012-09-01

    Full Text Available Telah dilakukan penelitian tentang sintesis lapis tipis berbasis nanopartikel titania termodifikasi silika (TiO2-SiO2 secara sol-gel sebagai bahan antifogging untuk (i mengetahui pengaruh temperatur kalsinasi terhadap energi band-gap, struktur dan ukuran kristal, serta porositas titania-silika, (ii mengetahui pengaruh komposisi sol terhadap karakteristik lapis tipis titania-silika yang meliputi hidrofilitas dan sifat transparan, serta (iii mengetahui kinerja antifogging lapis tipis titania-silika pada substrat kaca. Sintesis dilakukan melalui  metode sol-gel. Teknik pelapisan pada kaca menggunakan teknik celup, kemudian diaplikasikan sebagai bahan anti-kabut. Hasil sintesis TiO2-SiO2 dikarakterisasi dengan XRD untuk mengetahui struktur dan ukuran kristal, SEM-EDX untuk mengetahui morfologi dan komposisi padatan, serta DR-UV untuk mengetahui band-gap TiO2-SiO2. Hasil karakterisasi menunjukkan bahwa TiO2-SiO2 dengan 15% b/b silika  pada temperatur kalsinasi 500°C memiliki ukuran partikel dan band gap optimum  yaitu masing-masing sebesar 11,15 nm dan  3,20 eV. Hasil ini bersesuaian dengan hasil pengukuran sudut kontak minimum yaitu sebesar sebesar 14,49°. Hasil uji kinerja antifogging menunjukkan bahwa lapis tipis TiO2-SiO2 memiliki kemampuan untuk digunakan sebagai bahan anti-kabut. The research on synthesis of thin layer Based on TiO2 nanoparticle modified silica by sol gel as antifogging materials has been conducted to (i determine the effect of calcination temperature on the gap energy, structure and size of crystal, and porous titania-silica, (ii determine the effect of sol composition on thin layer titania-silica covering hydrophilic and transparent character, and (iii determine the performance of antifogging thin layer titania-silica on glass substrate. The synthesis is done by using sol-gel method. Dye technique was used to coat the glass, and then applied as antifogging materials. The result of synthesis of TiO2-SiO2

  7. 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 ZrO2 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 ZrO2 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.

  8. Monitoring of the Viability of Cells Immobilized by Sol-Gel Process

    Czech Academy of Sciences Publication Activity Database

    Kuncová, Gabriela; Podrazký, Ondřej; Ripp, S.; Trögl, Josef; Sayler, G. S.; Demnerová, K.; Vaňková, Radomíra

    2004-01-01

    Roč. 31, 1-3 (2004), s. 335-342 ISSN 0928-0707. [International Workshop on Sol-Gel and Technology-Part I (Sol-Gel'03) /12./. Sydney, 25.08.2003-29.08.2003] R&D Projects: GA ČR GA104/01/0461; GA MŠk OC 840.20; GA MŠk OC 840.10 Institutional research plan: CEZ:AV0Z4072921 Keywords : sol-gel process * cell entrapment * viability Subject RIV: CE - Biochemistry Impact factor: 1.150, year: 2004

  9. 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.

  10. Preparation of silica by sol-gel method using formamide

    Directory of Open Access Journals (Sweden)

    R.F.S. Lenza

    2001-07-01

    Full Text Available In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR, shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.

  11. Synthesis of Titania-Silica Materials by Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rubia F. S. Lenza

    2002-10-01

    Full Text Available In this work TiO2-SiO2 glasses containing as much as 20 mol % of TiO2 were prepared via sol-gel process using titanium and silicon alkoxides, in the presence of chlorine, in the form of titanium tetrachloride or HCl. The gels were heat-treated until 800 °C. X-ray diffraction and Fourier transform infrared spectroscopy were used to understand the structural properties of TiO2-SiO2 oxides calcined at different temperatures and to evaluate the homogeneity of these materials. The degree of the compactness of the silica network is inferred from the frequency of the asymmetric stretching vibrations of Si-O-Si bonds. Formation of Si-O-Ti bridges, as monitored by the intensity of characteristic 945 cm-1 ¾ 960 cm-1 vibration, is particularly prominent if the method of basic two-step prehydrolysis of silicon alkoxide, addition of titanium alkoxide and completion of hydrolysis was used.

  12. Synthesis of Carbon Nanotubes Using Sol Gel Route

    Science.gov (United States)

    Abdel-Fattah, Tarek

    2002-12-01

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

  13. Iron Oxide Silica Derived from Sol-Gel Synthesis

    Directory of Open Access Journals (Sweden)

    João Carlos Diniz da Costa

    2011-02-01

    Full Text Available In this work we investigate the effect of iron oxide embedded in silica matrices as a function of Fe/Si molar ratio and sol pH. To achieve homogeneous dispersion of iron oxide particles, iron nitrate nonahydrate was dissolved in hydrogen peroxide and was mixed with tetraethyl orthosilicate and ethanol in a sol-gel synthesis method. Increasing the calcination temperature led to a reduction in surface area, although the average pore radius remained almost constant at about 10 Å, independent of the Fe/Si molar ratio or sol pH. Hence, the densification of the matrix was accompanied by similar reduction in pore volume. However, calcination at 700 °C resulted in samples with similar surface area though the iron oxide content increased from 5% to 50% Fe/Si molar ratio. As metal oxide particles have lower surface area than polymeric silica structures, these results strongly suggest that the iron oxides opposed the silica structure collapse. The effect of sol pH was found to be less significant than the Fe/Si molar ratio in the formation of molecular sieve structures derived from iron oxide silica.

  14. Infrared Spectroscopy Studies on sol-gel prepared alumina Powders

    Directory of Open Access Journals (Sweden)

    Majid JAFAR TAFRESHI

    2015-03-01

    Full Text Available Gamma-alumina fine particles were synthesized by sol-gel process. Aluminum tri-sec-butoxide (ATB, anhydrous ethyl alcohol (EtOH, water (H2O and hydrochloric acid (HCl were used as starting materials. Different samples were synthesized with EtOH/ATB=60/1, HCl/ATB=0.08/1 and H2O/ATB=1/1 ratios and calcined at different temperatures. Molar ratios of H2O/ATB (from 1 to 25 and HCl/ATB (from 0.08 to 0.4 were changed for some other samples, during synthesizing process. The products were characterized by both XRD and FTIR measurements. Studies were carried out on the effect of calcination temperature and change of H2O/ATB and HCl/ATB ratios on structure and processes involved in phase transformations.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.4872

  15. Characterization of carbon cryogels synthesized by sol-gel polycondensation

    Directory of Open Access Journals (Sweden)

    BILJANA BABIC

    2005-02-01

    Full Text Available Resorcinol-formaldehyde (RF cryogels were synthesized by the sol-gel polycondensation of resorcinol (R with formaldehyde (F and freeze-drying was carried out with t-butanol. Carbon cryogels were obtained by pyrolyzing RF cryogels in an inert atmosphere. Characterization by nitrogen adsorption showed that the carbon cryogels were micro and mesoporous materials with high specific surface areas (SBET ~ 550 m2/g. Cyclic voltammetry experiments at various scan rates (2 to 200 mV s-1 were performed to study the electrical double-layer charging of carbon cryogel electrodes in 0.5 mol dm-3 HClO4 solution. It has been demonstrated that it is possible to sub-divide the total specific capacitance into the mesoporous and the microporous specific capacitance by analyzing the linear dependence of the charge (q on the reciprocal of the square root of the potential scan rate (v-1/2, and the linear dependence of the reciprocal charge (1/q on the square root of the potential scan rate (v-1/2. The specific capacitance was found to be constant over a wide range of sample weight (12.5 to 50.0 mg and a very promising specific capacitance value of 150 F/g, was found for this material operating in an acidic 0.5 mol dm-3 HClO4 solution at room temperature.

  16. Sol-Gel Titanium Dioxide Nanoparticles: Preparation and Structural Characterization

    Directory of Open Access Journals (Sweden)

    Oon Lee Kang

    2016-01-01

    Full Text Available Titanium dioxide (TiO2 nanoparticle was achieved in an alternative sol-gel route, as involved in 1 M acidic solution: HCl-tetrahydrofuran (HCl-THF, HNO3-tetrahydrofuran (HNO3-THF, and ClHNO2-tetrahydrofuran (ClHNO2-THF solution. Resultant TiO2 nanoparticle was further investigated in a systematic analytical approach. Nanoscale TiO2 structure was observed at a moderate hydrolysis ratio (8≤RH≤16. Particle size range was much narrower in an aprotic HNO3-THF medium, as compared to a differential HCl-THF medium. Biphasic TiO2 structure was detected at a certain hydrolysis ratio (RH≥16. Even so, relative anatase content was rather insignificant in an aprotic HCl-THF medium, as compared to a differential HNO3-THF medium. Tetragonal TiO2 structure was observed in the entire hydrolysis ratio (4≤RH≤32. Interstitial lattice defect was evident in an aprotic HNO3-THF medium but absent in a differential ClHNO2-THF medium.

  17. Amoeba-like self-oscillating polymeric fluids with autonomous sol-gel transition.

    Science.gov (United States)

    Onoda, Michika; Ueki, Takeshi; Tamate, Ryota; Shibayama, Mitsuhiro; Yoshida, Ryo

    2017-07-13

    In the field of polymer science, many kinds of polymeric material systems that show a sol-gel transition have been created. However, most systems are unidirectional stimuli-responsive systems that require physical signals such as a change in temperature. Here, we report on the design of a block copolymer solution that undergoes autonomous and periodic sol-gel transition under constant conditions without any on-off switching through external stimuli. The amplitude of this self-oscillation of the viscosity is about 2,000 mPa s. We also demonstrate an intermittent forward motion of a droplet of the polymer solution synchronized with the autonomous sol-gel transition. This polymer solution bears the potential to become the base for a type of slime-like soft robot that can transform its shape kaleidoscopically and move autonomously, which is associated with the living amoeba that moves forward by a repeated sol-gel transition.

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

    National Research Council Canada - National Science Library

    Xiaodong Wang; Guangming Wu; Bin Zhou; Jun Shen

    2013-01-01

      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...

  19. Infrared wire-grid polarizer with sol-gel antireflection films on both sides

    Science.gov (United States)

    Yamada, Itsunari; Ishihara, Yoshiro

    2017-12-01

    We fabricated an infrared wire-grid polarizer with the high transverse magnetic (TM) polarization transmittance and high extinction ratio by soft imprint lithography, sol-gel method, and Al shadow coating processes. A zilconia film was coated on Si substrate by using sol-gel method and spin coating method. Then, sol-gel zirconia grating was formed on the back side using imprinting using a silicone mold. The polarizer was produced by depositing Al obliquely on the grating. The TM transmittance of the fabricated element was greater than 80% at a wavelength of 4.8 μm. The sol-gel zilconia films acted as antireflection films. The extinction ratio exceeded 26 dB at its wavelength.

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

    Science.gov (United States)

    Sasaki, Darryl Y.; Brinker, C. Jeffrey; Ashley, Carol S.; Daitch, Charles E.; Shea, Kenneth J.; Rush, Daniel J.

    2000-01-01

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

  1. Preparation of YBCO superconductor nanoparticles by sol-gel combustion method

    National Research Council Canada - National Science Library

    M Farbod; M Tayeb Taher; I Kazeminezhad

    2010-01-01

    This paper describes the details of synthesizing nano crystalline YBCO superconductor using a sol-gel combustion method and the effect of sol pH and sintering temperature on particle size was investigated...

  2. [Effects of Sol-Gel coating on the corrosion resistance of nickel-chronium alloys].

    Science.gov (United States)

    Li, Lei; Zhu, Zhi-Min; Liao, Yun-Mao

    2009-02-01

    To investigate the effects of Sol-Gel coating on the corrosion resistance of nickel-chronium alloys in vitro. The bond strength of coating-substrate interface sintered at different temperatures (300, 400, 500, 600 degrees C) was tested by scratching method. The Sol-Gel coating was analyzed by scanning electron microscope (SEM), and its corrosion resistance was assessed by a static immersion method. The bond strength of coating-substrate interface reaches the peak at 400 degrees C. The Sol -Gel coating can apparently inhibit the release of metal ions and improve the corrosion resistance of nickel-chromium alloy. Sol-Gel coating can evidently improve corrosion resistance of the nickel-chromium alloy, which has great potential in prospective clinical practice.

  3. Amoeba-like self-oscillating polymeric fluids with autonomous sol-gel transition

    Science.gov (United States)

    Onoda, Michika; Ueki, Takeshi; Tamate, Ryota; Shibayama, Mitsuhiro; Yoshida, Ryo

    2017-07-01

    In the field of polymer science, many kinds of polymeric material systems that show a sol-gel transition have been created. However, most systems are unidirectional stimuli-responsive systems that require physical signals such as a change in temperature. Here, we report on the design of a block copolymer solution that undergoes autonomous and periodic sol-gel transition under constant conditions without any on-off switching through external stimuli. The amplitude of this self-oscillation of the viscosity is about 2,000 mPa s. We also demonstrate an intermittent forward motion of a droplet of the polymer solution synchronized with the autonomous sol-gel transition. This polymer solution bears the potential to become the base for a type of slime-like soft robot that can transform its shape kaleidoscopically and move autonomously, which is associated with the living amoeba that moves forward by a repeated sol-gel transition.

  4. Porous alumina scaffold produced by sol-gel combined polymeric sponge method

    Science.gov (United States)

    Hasmaliza, M.; Fazliah, M. N.; Shafinaz, R. J.

    2012-09-01

    Sol gel is a novel method used to produce high purity alumina with nanometric scale. In this study, three-dimensional porous alumina scaffold was produced using sol-gel polymeric sponge method. Briefly, sol gel alumina was prepared by evaporation and polymeric sponge cut to designated sizes were immersed in the sol gel followed by sintering at 1250 and 1550°C. In order to study the cell interaction, the porous alumina scaffold was sterilized using autoclave prior to Human Mesenchymal Stem Cells (HMSCs) seeding on the scaffold and the cell proliferation was assessed by alamarBlue® assay. SEM results showed that during the 21 day period, HMSCs were able to attach on the scaffold surface and the interconnecting pores while maintaining its proliferation. These findings suggested the potential use of the porous alumina produced as a scaffold for implantation procedure.

  5. Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

    Directory of Open Access Journals (Sweden)

    Geneviève Chadeyron

    2009-09-01

    Full Text Available Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3.

  6. Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

    Science.gov (United States)

    García-Hernández, Margarita; García-Murillo, Antonieta; de J. Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-01-01

    Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3. PMID:19865533

  7. Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

    OpenAIRE

    Geneviève Chadeyron; Damien Boyer; Elder De la Rosa; David Jaramillo-Vigueras; Carrillo-Romo, Felipe de J.; Antonieta García-Murillo; Margarita García-Hernández

    2009-01-01

    Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3.

  8. Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

    Science.gov (United States)

    García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-09-17

    Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu(3+) doped BaTiO(3).

  9. Polyimide/silica hybrids via the sol-gel route: High performance materials for the new technological challenges

    Directory of Open Access Journals (Sweden)

    2009-07-01

    Full Text Available The present review article describes in detail the state-of-the-art of organic-inorganic hybrid materials based on polyimide/silica components. The article is divided in three parts. In the first the basic processing route for the preparation of these systems is described, i.e. the sol-gel technique, along with the strategies developed to control the final morphology. In the second part the curing characteristics, the dynamic-mechanical and the mechanical and fracture properties of hybrids with different morphologies are reviewed. Finally, the more technologically relevant applications devised for these high performance materials are discussed.

  10. Making MgO/SiO2 Glasses By The Sol-Gel Process

    Science.gov (United States)

    Bansal, Narottam P.

    1989-01-01

    Silicon dioxide glasses containing 15 mole percent magnesium oxide prepared by sol-gel process. Not made by conventional melting because ingredients immiscible liquids. Synthesis of MgO/SiO2 glass starts with mixing of magnesium nitrate hexahydrate with silicon tetraethoxide, both in alcohol. Water added, and transparent gel forms. Subsequent processing converts gel into glass. Besides producing glasses of new composition at lower processing temperatures, sol-gel method leads to improved homogeneity and higher purity.

  11. Preparation, characterization, and biological properties of organic-inorganic nanocomposite coatings on titanium substrates prepared by sol-gel.

    Science.gov (United States)

    Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando

    2014-02-01

    When surface-reactive (bioactive) coatings are applied to medical implants by means of the sol-gel dip-coating technique, the biological proprieties of the surface of the implant can be locally modified to match the properties of the surrounding tissues to provide a firm fixation of the implant. The aim of this study has been to synthesize, via sol-gel, organoinorganic nanoporous materials and to dip-coat a substrate to use in dental applications. Different systems have been prepared consisting of an inorganic zirconium-based matrix, in which a biodegradable polymer, the poly-ε-caprolactone was incorporated in different percentages. The materials synthesized by the sol-gel process, before gelation, when they were still in sol phase, have been used to coat a titanium grade 4 (Ti-4) substrate to change its surface biological properties. Thin films have been obtained by means of the dip-coating technique. A microstructural analysis of the obtained coatings was performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. The biological proprieties have been investigated by means of tests in vitro. The bone-bonding capability of the nanocomposite films has been evaluated by examining the appearance of apatite on their surface when plunged in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. The examination of apatite formation on the nanocomposites, after immersion in SBF, has been carried out by SEM equipped with energy-dispersive X-ray spectroscopy. To evaluate cells-materials interaction, human osteosarcoma cell line (Saos-2) has been seeded on specimens and cell vitality evaluated by WST-8 assay. © 2013 Wiley Periodicals, Inc.

  12. 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.

  13. Preparation and antioxidant capacity of element selenium nanoparticles sol-gel compounds.

    Science.gov (United States)

    Bai, Yan; Qin, Biyin; Zhou, Yanhui; Wang, Yudong; Wang, Zi; Zheng, Wenjie

    2011-06-01

    This paper reported the preparation and antioxidant capacities of element selenium nanoparticles (nanoSe(0))-ascorbic acid (Vc) sol and nanSe(0)/Vc/selenocystine (SeCys) sol-gel compounds. NanoSe(0)-Vc sol was prepared by reduction of selenious dioxide (SeO2) with Vc. In the nanoSe(0)-Vc sol, highly concentrated Vc was also used as a modifier to modulate the diameter of Se(0) nanoparticles in the liquid phase. Then excellent nanoSe(0) sol-gel compounds were obtained by adding SeCys into the nanoSe(0)-Vc sol. The structure of the nanoSe(0)/Vc/SeCys sol-gel compounds was defined, which was constructed via C-Se, Se-H and O=C-Se valences and by interaction between SeCys and Vc via peptide bonds, esterification and dehydration. The antioxidant capacities of the nanoSe(0)-Vc sol and the nanoSe(0)Vc/SeCys sol-gel compounds were estimated by oxygen radical absorption capacity (ORAC) assay. The nanoSe(0)/Vc/SeCys sol-gel compounds possessed a strong antioxidant capacity due to forming the perfect three-dimensional (3D) frameworks structure. The results suggested that the nanoSe(0)-Vc sol and the nanoSe(0)Vc/SeCys sol-gel compounds might be potential medicine, especially antioxidant.

  14. Optical Behavior by Congo Red Doped in Polymer and Sol-Gel Film

    Directory of Open Access Journals (Sweden)

    A. Kazemzadeh

    2010-02-01

    Full Text Available A pH Chemical sensor with high sensitivity is achieved by direct attachment of Cong Red indicator over a Sol-Gel and polymeric film. This sensor is prepared by attaching Congo red over polymeric film or by adding indicator in tetra metoxysilan (TMOS in order to determining hydrogen ion in solution with high concentration of hydrogen and producing strong signals and rapid response time. Congo red is used over a Sol-Gel or polymeric film as a chemical-optical sensor. Sol-Gel layer and polymeric membrane have long lifetime as (>15 months and (>12 months and short response time as (>6 sec and (>9 sec respectively. It is a simple method and applied dye has low price and highly used. In this paper, the purpose is investigation and optimizing condition for Sol-Gel layer and polymeric film. Finally morphology of polymeric film and Sol-Gel layer surfaces were investigated by AFM apparatus and subsequently Sol-Gel layer have been found to be a favorite base for chemical sensor a fabrication.

  15. 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

    determined with spectral ellipsometry. The presented investigations were able to show that the developed low temperature sol-gel process using the spin-coating technique is suitable for the preparation of simple AR and HR multilayer systems. (orig.)

  16. Synthesis and characterization of mixtures of cobalt and titanium oxides by mechanical alloyed and Sol-Gel;Sintesis y caracterizacion de mezclas de oxidos de cobalto y titanio por aleado mecanico y Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Basurto S, R.; Bonifacio M, J.; Fernandez V, S. M., E-mail: rafael.basurto@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2009-07-01

    The mechanical alloyed techniques continued by combustion and Sol-Gel method, were used for the synthesis of CoTiO{sub 3}. With the first technique was used Co{sub 3}O{sub 4} obtained in a balls mill SPEX in argon atmosphere, using cobalt nitrate and urea, the combustion is realized at 400 and 500 C, the characterization by X-ray diffraction showed the obtaining of the valence oxide mixed of cobalt with crystallite size from 10 to 12.5 nm and the particle size of 60 to 75 nm was obtained by scanning electron microscopy. To prepare the CoTiO{sub 3}, the obtained Co{sub 3}O{sub 4} was mixed with TiO{sub 2} on a relationship in weight (1:1) and with a milling time of 2.5 h and the combustion at 800 C. the mixed oxide of titanium cobalt was also obtained by the Sol-Gel technique starting from cobalt chloride and titanium propoxide in acetic-water acid, the gel is burned to temperature of 300, 500, 700 and 900 C, finding that this last temperature it is that provides the compound with crystalline size from 50 to 75 nm. (Author)

  17. Review and the state of the art: Sol-gel and melt quenched bioactive glasses for tissue engineering.

    Science.gov (United States)

    Kaur, Gurbinder; Pickrell, Gary; Sriranganathan, Nammalwar; Kumar, Vishal; Homa, Daniel

    2016-08-01

    Biomaterial development is currently the most active research area in the field of biomedical engineering. The bioglasses possess immense potential for being the ideal biomaterials due to their high adaptiveness to the biological environment as well as tunable properties. Bioglasses like 45S5 has shown great clinical success over the past 10 years. The bioglasses like 45S5 were prepared using melt-quenching techniques but recently porous bioactive glasses have been derived through sol-gel process. The synthesis route exhibits marked effect on the specific surface area, as well as degradability of the material. This article is an attempt to provide state of the art of the sol-gel and melt quenched bioactive bioglasses for tissue regeneration. Fabrication routes for bioglasses suitable for bone tissue engineering are highlighted and the effect of these fabrication techniques on the porosity, pore-volume, mechanical properties, cytocompatibilty and especially apatite layer formation on the surface of bioglasses is analyzed in detail. Drug delivery capability of bioglasses is addressed shortly along with the bioactivity of mesoporous glasses. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1248-1275, 2016. © 2015 Wiley Periodicals, Inc.

  18. Solid-phase microextraction of methadone in urine samples by electrochemically co-deposited sol-gel/Cu nanocomposite fiber.

    Science.gov (United States)

    Mohammadiazar, Sirwan; Hasanli, Fateme; Maham, Mehdi; Payami Samarin, Somayeh

    2017-08-01

    Electrochemically co-deposited sol-gel/Cu nanocomposites have been introduced as a novel, simple and single-step technique for preparation of solid-phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol-gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC-UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL(-1) . Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

    Bagheri, Habib; Piri-Moghadam, Hamed

    2012-09-01

    A novel molecularly imprinted xerogel (MIX) based on organically modified silica (ORMOSIL) was successfully prepared for on-line capillary microextraction (CME) coupled with high-performance liquid chromatography (HPLC). The sol-gel-based xerogel was prepared using only one precursor and exhibited extensive selectivity towards triazines along with significant thermal and chemical stability. Atrazine was selected as a model template molecule and 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) as a precursor in which the propylmethacrylate moiety was responsible for van der Waals, dipole-dipole, and hydrogen-bond interactions with the template. This moiety plays a key role in creation of selective sites while methoxysilyl groups in TMSPMA acted as crosslinkers between the template and the propylmethacrylate moiety. Moreover, a non-imprinted xerogel (NIX) was also prepared in the absence of the template for evaluating the extraction efficiency of the prepared MIX. Then, the prepared imprinted and non-imprinted xerogels were used for extraction of three selected analytes of triazines class including atrazine, ametryn, and terbutryn, which have rather similar structures. The extraction efficiency of the prepared xerogel for atrazine, the template molecule, was found to be ten times greater than the efficiency achieved by the non-imprinted one. In the meantime, the extraction efficiency ratio of MIX to NIX for ametryn and terbutryn was also rather significant (eight times). Moreover, other compounds from different classes including dicamba, mecoprop, and estriol were also analyzed to evaluate the selectivity of the prepared MIX towards triazines. The ratio of enrichment factors (EF) of MIX to NIX for atrazine, ametryn, terbutryn, dicamba, mecoprop, and estriol were about 10, 8, 8, 2, 2, and 3, respectively. The linearity for the analytes was in the range of 5-700 μg L(-1). Limit of detection was in the range of 1-5 μg L(-1) and the RSD% values (n = 5) were all below 6

  20. Optical sensing of HCl with phenol red doped sol-gels

    Energy Technology Data Exchange (ETDEWEB)

    Wang Enju [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States)]. E-mail: wange@stjohns.edu; Chow, Kwok-Fan [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Wang Wenqun [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Wong, Crystal [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Yee, Cynthia [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Persad, Alvin [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Mann, Jonathan [Department of Chemistry, Princeton University, Princeton, NJ 08540 (United States); Bocarsly, Andrew [Department of Chemistry, Princeton University, Princeton, NJ 08540 (United States)

    2005-04-08

    A dye doped sol-gel for the sensing of hydrochloric acid in solution and/or gaseous phase is described. The sol-gel is obtained by acidic hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (Ph-TriEOS) in the presence of phenol red (PR) and further spin-coating onto glass slides. The sensitive response is based on an increase of the absorption band at 510 nm of phenol red entrapped in the sol-gel casting when exposed to HCl solution or gas, due to protonation of the dye. The detection limit of the sol-gel response to moisturized gaseous HCl is below 12 ppm, and its response to HCl in solution falls in the range of 0.01-6 M. The sol-gel coating has a response time of less than 40 s in steady-state, and life-time of more than a year. Weak acids such as acetic acid, benzoic acid, salicylate acid, citrate acid, and carbonic acid do not interfere the response. The responses in acid solutions are completely reversible. In the gaseous phase, response of HCl appears to be moisture sensitive.

  1. Modified thermoresponsive Poloxamer 407 and chitosan sol-gels as potential sustained-release vaccine delivery systems

    DEFF Research Database (Denmark)

    Kojarunchitt, Thunjiradasiree; Baldursdottir, Stefania; Dong, Yao-Da

    2015-01-01

    A and monophosphoryl lipid A), were free-flowing liquids at room temperature and formed stable gels at physiological temperatures. Rheological results showed that both systems meet the criteria of being thermoresponsive gels. The P407-25R4 sol-gels did not significantly sustain the release of antigen in vivo while...... the chitosan-MC sol-gels sustained the release of antigen up to at least 14 days after administration. The chitosan-MC sol-gels stimulated both cellular and humoral responses. The inclusion of cubosomes in the sol-gels did not provide a definitive beneficial effect. Further analysis of the formulations...

  2. Characterization of nano porous TiO{sub 2} films prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Sabataityte, J.; Oja, I.; Volobujeva, O.; Krunks, M. [Tallinn University of Technology, Dept. of Materials Science (Estonia); Lenzmann, F. [Solar Energy Department, ECN, Westerduinweg, Petten (Netherlands); Sabataityte, J. [Semiconductor Physics Institute, Vilnius (Lithuania)

    2006-05-15

    Nano-porous TiO{sub 2} films as a key component in dye sensitized and extremely thin absorber (ETA) solar cells were prepared by the sol-gel method using spin-coating and spray pyrolysis deposition techniques. The precursor sol contained titanium (IV) iso-prop-oxide, acetylacetone and polyethylene glycol (PEG) in ethanol. Glass and n-type Si (100) were used as substrates. SEM, XRD and FT-IR were used to study the effect of the PEG concentration in the precursor solution as well as different annealing routes on the film composition and structural properties. Crystalline films with anatase structure could be grown by the spray technique at 500 C. Post-annealing at 500 C increases the crystallite size (from 5 to 9 nm) and results in an average pore size around 40 nm. A film thickness of about 2.3 {mu}m is attained using 50 spray pulses. In spin coated films the formation of Ti-O-Ti anatase bonds is observed after annealing at 450 C. Crystalline films can be prepared by annealing at temperatures above 700 C. Surface morphology and pore size of spin coated films are controlled by the amount of PEG in the sol. The film thickness is around 120 nm after three coating cycles. (authors)

  3. Characterization in vitro studies and antibacterial properties on a sol-gel derived silver incorporated bioglass

    Science.gov (United States)

    Bouhazma, S.; Chajri, S.; Khaldi, M.; Sadiki, M.; Barkai, H.; Elabed, S.; Ibnsouda Koraichi, S.; El Bali, B.; Lachkar, M.

    2017-03-01

    The SiO2-CaO, SiO2-CaO-P2O5 and SiO2-CaO-P2O5-Ag2O glass systems were synthesized by the sol-gel technique and characterized with different techniques such as X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Environmental Scanning Electron Microscopy (ESEM). In vitro bioactivity tests were performed in Simulated Body Fluid (SBF). The antibacterial action of 65S5Ag (65%SiO2 + 24%CaO + 6%P2O5 + 5% Ag2O) is attributed exclusively to the leaching of Ag+ ions from the glass matrix. The activity of SiO2-CaO-P2O5-Ag2O was compared with that of its binary and ternary counterpart glass system. The concentrations of Ag-bioglass, in the range of 0.05 mg/mL of culture medium, were found to inhibit the growth of these bacteria.

  4. Ellipsometric spectroscopy study of cobalt oxide thin films deposited by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Barrera-Calva, E.; Martinez-Flores, J.C. [Departamento de Ingenieria de Procesos e Hidraulica, UAM ? Iztapalapa, Av. Rafael Atlixco No. 186, Col. Vicentina, Mexico DF 09340 (Mexico); Huerta, L. [Instituto de Investigacion en Materiales, Universidad Nacional Autonoma de Mexico, Mexico DF (Mexico); Avila, A.; Ortega-Lopez, M. [Depto. Ingenieria Electrica, SEES, CINVESTAV- IPN, Mexico DF 07360 (Mexico)

    2006-09-22

    Due to their unique optical properties, solar selective coatings enhance the thermal efficiency of solar photothermal converters. Hence it seems to be interesting to study the optical properties of promising materials as solar selective coatings. In an earlier work, it was demonstrated that sol-gel deposited cobalt oxide thin films possess suitable optical properties as selective coatings. In this work, cobalt oxide thin films were prepared by same technique and their optical properties were analyzed as a function of the dipping time of the substrate in the sol, using the spectroscopy ellipsometry, atomic force microscopy and X-ray photoelectron spectroscopy techniques. The optical constants (n and k) for these films, in the 200-800nm range, are reported as a function of the dipping time. The fitting of ellipsometric data, I{sub s} and I{sub c}, for the glass substrate and the cobalt oxide thin film, as modeled with the Lorentz and Tauc-Lorentz dispersion relations, indicated that the film microstructure resembles a multilayer stack with voids. From these results, the Co{sub 3}O{sub 4} and void percentages in the film were estimated. Both, thin film thickness and void/Co{sub 3}O{sub 4} percentage ratio, were determined to be strongly dependent on the immersion time. Furthermore, the total thickness of a multilayered film was found to be the sum of thickness of each individual layer. (author)

  5. Antibacterial effect of bioactive glass nanoparticles prepared via sol gel method

    Directory of Open Access Journals (Sweden)

    Zahra Nazemi

    2014-10-01

    Full Text Available Background: Infection constitutes the most important complication caused by biomaterials. Bioactive glasses have properties such as osteoconductivity and good restorability, some of which have revealed antibacterial effects. Therefore, these biomaterials are appropriate candidates for orthopedic and dental applications. The present study was conducted to analyze the antibacterial effect of bioactive glass nanoparticles. Methods: In this experimental study, 37S and 58S glass compositions were synthesized via sol-gel technique. Characterization techniques such as X-ray diffraction (XRD, scanning electron microscopy (SEM and X-ray fluorescent (XRF were used for the prepared powders. The antibacterial activity of these compounds was studied using Escherichia coli as gram negative and Staphylococcus aureus as gram positive bacteria. The antibacterial effect of samples was evaluated at concentration of 25, 50 and 100 mg/ml. Results: The particle size of the samples was mainly less than 100 nm. The 37S glass showed the highest antibacterial activity and the minimum bactericidal (MBC at 25 mg/ml concentration against both bacteria. At broth concentrations below 100 mg/ml, 58S showed no antibacterial activity; however, it completely eliminated Escherichia bacteria and reduced the growth of Staphylococcus aureus bacteria. Conclusion: These bioactive glass nanopowders can be regarded as good candidates in orthopedic application for the treatment of bone and dental defects but need supplementary and more evaluation considering their antibacterial effect on two important bacteria.

  6. Synthesis and Characterization of Anatase Titanium Dioxide Nanoparticles Using Egg White Solution via Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Samira Bagheri

    2013-01-01

    Full Text Available Anatase titanium dioxide nanoparticles (TNPs are synthesized by a simple and cost-effective process with and without freshly water-soluble egg white proteins (albumin via sol-gel method. The main advantage of using egg white proteins as a gelling agent is that it can provide long-term stability for nanoparticles by preventing particles agglomeration. The X-ray diffraction and FTIR results indicate that the synthesized nanoparticles have only the anatase structure without the presence of any other phase impurities. Additionally, the TNPs are characterized by a number of techniques such as thermogravimetric analysis (TGA, X-ray diffraction analysis (XRD, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FTIR, and ultraviolet visible spectra (UV-vis. The sizes of titanium dioxide nanoparticles with and without using egg white solution are 12.55±3.42 nm and 21.45±4.21 nm, respectively. The results indicate that egg white solution is a reliable and cheap green gelling agent that can be used as a matrix in the sol-gel method to synthesis tiny size TNPs.

  7. Preparation and characterization of quercetin-loaded silica microspheres stabilized by combined multiple emulsion and sol-gel processes

    Directory of Open Access Journals (Sweden)

    Kim Young Ho

    2015-01-01

    Full Text Available Despite exhibiting a wide spectrum of cosmeceutical properties, flavonoids and related compounds have some limitations related to their stability and solubility in distilledwater. In this project, we prepared silica microspheres using a novel method that uses polyol-in-oil-in-water (P/O/W emulsion and sol-gel methods as techniques for stabilizing quercetin. A stable microsphere suspension was successfully preparedusing a mixed solvent system comprising a polyol-phase medium for performing the sol-gel processing of tetraethyl orthosilicate (TEOS as an inorganic precursor with outer water phase. The morphology of the microsphere was evaluated using a scanning electron microscope (SEM, which showed a characteristic spherical particle shape with a smooth surface. Furthermore, SEM/EDSanalysis of a representative microsphere demonstrated that the inner structure of the silica microspheres was filled with quercetin. The mean diameter of the microsphere was in the range 20.6-35.0 μm, and the encapsulation efficiency ranged from 17.8% to 27.5%. The free and encapsulated quercetin samples were incubated in separateaqueous solutions at 25 and 42°C for 28 days. The residualcontent of the quercetin encapsulated by silica microspheres was 82% at 42°C. In contrast, that of the free quercetin stored at 42°C decreased to ~24%.

  8. Surfactant-Assisted Sol-Gel Synthesis of TiO2 with Uniform Particle Size Distribution

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    O. L. Galkina

    2011-01-01

    Full Text Available TiO2 materials were prepared from a titanium isopropoxide precursor by sol-gel processing in water media with or without various templates (polyethylenimine or Pluronic P-123. The photocatalytic efficiency of the samples was found to depend strongly on the use of and type of template added. Titania/Pluronic sols resulted in homogeneous anatase TiO2—rutile with uniform particle size distribution after calcination (400°C. Optical properties of the samples were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase and rutile titania, which resulted in smaller grain sizes and presumably a larger active surface area. The morphology of the surfaces was obtained by AFM techniques. The highest photobleaching rate was found for samples deposited from the sol with the addition of the Pluronic P-123 surfactant, and it was almost twice as high as that for films deposited from sols with polyethylenimine.

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

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Paulo Herbert Franca; Lima, Francisco Marcone; Sena, Aline Cosmo de; Silva, Alvaro Neuton; Almeida, Ana Fabiola Leite de; Freire, Francisco Nivaldo Aguiar, E-mail: phfmj@yahoo.com.br, E-mail: marconeufc@gmail.com, E-mail: alinedesena@yahoo.com.br, E-mail: alvaro_neutron@hotmail.com, E-mail: anfaleal@yahoo.com.br, E-mail: nivaldo@ufc.br [Universidade Federal do Ceara (UFCE), CE (Brazil)

    2014-07-01

    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{sub 4}F and SnCl{sub 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{sub 2} network. (author)

  10. Influence of some sol-gel synthesis parameters of mesoporous TiO2 on photocatalytic degradation of pollutants

    Directory of Open Access Journals (Sweden)

    Golubović Aleksandar

    2016-01-01

    Full Text Available The titanium dioxide (TiO2 nanopowders were produced by sol-gel technique from tetrabutyl titanate as a precursor by varying some parameters of the sol-gel synthesis like the temperature (500 and 550 °C and the duration of the calcination (1.5, 2, and 2.5 h. X-ray powder diffraction (XRPD results have shown that all synthesized nanopowders are dominantly in anatase phase, with the presence of a small amount of rutile in samples calcined at 550 °C. According to the results obtained by Williamson-Hall method, the anatase crystallite size was increased with the duration of the calcination (from 24 to 29 nm in samples calcined at lower, and from 30 to 35 nm in samples calcined at higher temperature. The analysis of the shift and linewidth of the most intensive anatase Eg Raman mode confirmed the XRPD results. The analysis of pore structure from nitrogen sorption experimental data described all samples as mesoporous, with mean pore diameters in the range of 5-8 nm. Nanopowder properties have been related to the photocatalytic activity, tested in degradation of the textile dye (C.I. Reactive Orange 16, carbofuran and phenol. [Projekat Ministarstva nauke Republike Srbije, br. III45018 i br. ON171032

  11. 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.

  12. Effects of densification atmosphere on optical properties of ionic copper-activated sol-gel silica glass: towards an efficient radiation dosimeter

    Science.gov (United States)

    El Hamzaoui, Hicham; Bouwmans, Géraud; Capoen, Bruno; Ouerdane, Youcef; Chadeyron, Geneviève; Mahiou, Rachid; Girard, Sylvain; Boukenter, Aziz; Bouazaoui, Mohamed

    2014-04-01

    Ionic copper-doped pure silica glass, with high photoluminescence (PL) quantum yield (QY), has been prepared using the sol-gel technique and densification of the porous xerogel under inert atmosphere. The optical properties of the obtained glass, and especially the green light emission due to Cu+ ions under UV excitation, have been studied and compared to those of the glass produced in air atmosphere conditions. We have shown that the sintering process under helium increases the quantum efficiency of this emission by a factor 40. Moreover, the resulting copper-doped silica rod has been used in the fabrication of a high numerical aperture microstructured optical fiber, which shows similar luminescent properties to the sol-gel preform. The obtained fiber exhibits promising characteristics to be employed in an all-fibred UV sensor. In particular, the high emission efficiency and the specific air-clad geometry of the fiber made it possible to perform measurements without removing the polymer coating.

  13. Structural and electrochemical behavior of sol-gel ZrO{sub 2} ceramic film on chemically pre-treated AZ91D magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Qing [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)], E-mail: liqingd@swu.edu.cn; Chen Bo; Xu Shuqiang; Gao Hui; Zhang Liang; Liu Chao [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2009-06-10

    In the present investigation sol-gel-based ZrO{sub 2} ceramic film was obtained using zirconium acetate as the precursor material. The film was deposited on AZ91D magnesium alloy by a dip-coating technique. An uniform stannate conversion coating as chemical pretreatment was employed as an intermediate layer prior to deposition of the ZrO{sub 2} film in order to provide advantage for the formation of sol-gel-based ZrO{sub 2} layer. The corrosion properties, structure, composition and morphology of these coatings on AZ91D magnesium alloy were studied by potentiodynamic polarization tests, EIS, XRD, SEM, respectively. According to the electrochemical tests, the corrosion resistance of AZ91D magnesium alloy was found to be greatly improved by means of this new environment-friendly surface treatment.

  14. 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-C12) and phenethyl (PhE) ligands. Here, the ability of the PF-C12 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-C12 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) (4

  15. Evaluation of Hydroxyapatite-Forsterite Glass Composite Nanopowder Prepared via Sol-Gel Method

    Science.gov (United States)

    Mazrooei Sebdani, Maryam; Fathi, Mohammadhossein

    In spite of attractive bioactivity of bioactive ceramics i.e. hydroxyapatite and bioactive glasses, their poor mechanical properties have restricted their clinical applications. To overcome these limitations, an alternative approach suggested is preparation a composite including these bioactive ceramics with others. It is expected that a ceramic reinforcement with reduced grain size below 100 nm promotes theirs. The aim of this work was fabrication and characterization of hydroxyapatite-forsterite-bioglass composite nanopowder. Novel hydroxyapatite-forsterite-bioglass composite nanopowder was synthesized by incorporation of the forsterite and bioactive glass in hydroxyapatite matrix via a sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy techniques were utilized in order to evaluate the phase composition, agglomerates size distribution, morphology and particle size and functional groups of synthesized. The effects of sintering temperature and time were also investigated. Results showed that the appropriate temperature for calcination was 600°C and the particle size of composite nanopowder was about 60-70nm. The decomposition of hydroxyapatite was increased with the increase of the sintering temperature and sintering time. Obtained results indicate that prepared composite nanopowder could be a good candidate for medical applications.

  16. 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

    1995-12-31

    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.

  17. Sol-Gel TiO2 thin films sensitized with the mulberry pigment cyanidin

    Directory of Open Access Journals (Sweden)

    Emerson Henrique de Faria

    2007-12-01

    Full Text Available TiO2 films have various applications, among them solar cells and photodegradation of pollutants. In this study, we investigated TiO2 films functionalized with the organic dye cyanidin extracted from black mulberry (Morus nigra. The TiO2 was functionalized by the sol-gel method and the film was deposited on glass substrates by dip-coating. Our aim was to investigate the interaction between the semiconductor and the dye, as well as the influence of the velocity and number of deposits on the characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye’s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

  18. Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

    Science.gov (United States)

    Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

    2017-12-01

    Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

  19. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Figus, Cristiana, E-mail: cristiana.figus@dsf.unica.it; Quochi, Francesco, E-mail: cristiana.figus@dsf.unica.it; Artizzu, Flavia, E-mail: cristiana.figus@dsf.unica.it; Saba, Michele, E-mail: cristiana.figus@dsf.unica.it; Marongiu, Daniela, E-mail: cristiana.figus@dsf.unica.it; Mura, Andrea; Bongiovanni, Giovanni [Dipartimento di Fisica - University of Cagliari, S.P. Km 0.7, I-09042 Monserrato (Canada) (Italy); Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia [Dipartimento di Fisica - University of Pavia, Via Agostino Bassi 6, I-27100 Pavia (PV) (Italy); Pellacani, Paola; Valsesia, Andrea [Plasmore S.r.l. -Via Grazia Deledda 4, I-21020 Ranco (Vatican City State, Holy See) (Italy)

    2014-10-21

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  20. Enhanced Magnetization of Sol-Gel Synthesized Pb-Doped Strontium Hexaferrites Nanocrystallites at Low Temperature

    Directory of Open Access Journals (Sweden)

    Shahid M. Ramay

    2014-01-01

    Full Text Available Effect of Pb doping on the structural and low temperature magnetic properties of SrPbxFe12-xO19 (x=0,0.1,0.2,0.3,and  0.4, synthesized by sol-gel autocombustion technique, has been investigated. The powder samples were sintered at 800°C for 2 h in order to develop the stable hexagonal phase, characteristic of the SrFe12O19 structure. The consequences of Pb substitution (at iron sites on various structural parameters like lattice constants, unit cell volume, crystallite size, and porosity have been discussed. Fourier transform infrared frequency bands were utilized to determine the formation of tetrahedral and octahedral clusters of M-type ferrites. Hexagonal texture of the grains, a characteristic of the hexagonal crystal structure of SrFe12O19, was refined by Pb substitution. The magnetic properties, determined using a vibrating sample magnetometer, revealed that saturation magnetization decreased, while coercivity was increased with the increase of Pb contents. However, the increased squareness ratio and hence the energy product motivate the utilization of these ferrite compositions where hard magnetic characteristics are required. The increased values of saturation magnetization were observed at reduced temperature of 200 K, attributable to the better spin alignments of individual magnetic moments at low temperature.

  1. 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.

  2. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  3. Preparation, microstructure and properties of yttrium aluminum garnet fibers prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Li Chengshun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Zhang Yujun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: yujunzhangcn@sdu.edu.cn; Gong Hongyu; Zhang Jingde; Nie Lifang [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-01-15

    Yttrium aluminum garnet (YAG) fiber was prepared by sol-gel method using water as the solvent. The spinnable YAG sol was synthesized using Al powder, Y(CH{sub 3}COOH){sub 3}.4H{sub 2}O and HCl as precursors, polyethylene oxide as viscosity adjusting agent. Gel fibers with diameter of 5-10 {mu}m were prepared from the YAG sol by using centrifugal spinning technique. YAG crystalline fibers were obtained by drying gel fibers and heat-treating at selected temperature. TG/DTA analysis showed an exotherm at 906 deg. C attributed to formation of YAG phase and weight loss of 45% at 1000 deg. C. XRD and FT-IR analysis showed that phase-pure YAG can be formed at 900 deg. C, and no other intermediate was observed. The grain size of YAG fibers increased from 25 to 220 nm and tensile strength decreased rapidly from 970 to 380 MPa when the sintering temperature increased from 900 to 1550 deg. C.

  4. Structural, optical and photocatalytic properties of sol-gel synthesized mesoporous TiO2 film.

    Science.gov (United States)

    Darzi, Simin Janitabar; Mahjoub, Ali Reza; Hosseinian, Akram

    2010-09-01

    TiO2 surfactant-templated nanostructured film was fabricated by supramolecular templating technique using TiCl4 and P-123 as raw material and surfactant, respectively. The film was produced by sol-gel dip coating procedure. Characterization of the product was carried out by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, thermogravimetry (TG), and UV-vis absorption spectroscopy. Detailed characterization reveals that film is transparent and has a wormlike mesostructured with high surface area. It is about 2 microm thick and is composed of closely packed anatase particles. The estimated band gap value of TiO2 thin film in the present work is 3.69 eV which is about 0.3 eV larger than value reported in literature for anatase thin film. It could be due to quantum size effect arising from the small size of TiO2 nanocrystallite in this thin film. The photocatalytic activity of the prepared TiO2 film was evaluated by Crystalviolet dye degradation. The film has excellent photocatalytic efficiencies and more than 70% of dye was decolorized in 60 minutes.

  5. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    Science.gov (United States)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  6. Synergic combination of the sol-gel method with dip coating for plasmonic devices.

    Science.gov (United States)

    Figus, Cristiana; Patrini, Maddalena; Floris, Francesco; Fornasari, Lucia; Pellacani, Paola; Marchesini, Gerardo; Valsesia, Andrea; Artizzu, Flavia; Marongiu, Daniela; Saba, Michele; Marabelli, Franco; Mura, Andrea; Bongiovanni, Giovanni; Quochi, Francesco

    2015-01-01

    Biosensing technologies based on plasmonic nanostructures have recently attracted significant attention due to their small dimensions, low-cost and high sensitivity but are often limited in terms of affinity, selectivity and stability. Consequently, several methods have been employed to functionalize plasmonic surfaces used for detection in order to increase their stability. Herein, a plasmonic surface was modified through a controlled, silica platform, which enables the improvement of the plasmonic-based sensor functionality. The key processing parameters that allow for the fine-tuning of the silica layer thickness on the plasmonic structure were studied. Control of the silica coating thickness was achieved through a combined approach involving sol-gel and dip-coating techniques. The silica films were characterized using spectroscopic ellipsometry, contact angle measurements, atomic force microscopy and dispersive spectroscopy. The effect of the use of silica layers on the optical properties of the plasmonic structures was evaluated. The obtained results show that the silica coating enables surface protection of the plasmonic structures, preserving their stability for an extended time and inducing a suitable reduction of the regeneration time of the chip.

  7. In situ growth of luminescent silver nanoclusters inside bulk sol-gel silica glasses

    Science.gov (United States)

    El Hamzaoui, Hicham; Capoen, Bruno; Razdobreev, Igor; Bouazaoui, Mohamed

    2017-07-01

    Silver nanocluster-doped glasses are attractive materials for various photonic applications. In this paper, bulk silica glasses doped with luminescent silver nanoclusters have been prepared using the sol-gel technique. As a first step, dense silica glasses doped with ionic silver have been loaded with hydrogen. Thereafter, a heat-treatment in air atmosphere was performed to enable the growth of silver nanoclusters at different temperatures in the range 100-600 °C. The optical properties of the obtained nanocomposites have been studied, as a function of the post-annealing temperature, using optical absorption and photoluminescence spectroscopies. It has been shown that, under UV photoexcitation, the hydrogenated samples, heat-treated between 200 and 500 °C present visible luminescence due to cationic and neutral molecular-like silver clusters, consisting of a small number of Ag atoms or ions. After annealing at 600 °C, further Ag aggregation led to 2 nm-size silver nanoparticles, resulting in a quenching of the visible luminescence.

  8. 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.

  9. Synthesis and characterization of polymer-silica hybrid latexes and sol-gel-derived films

    Energy Technology Data Exchange (ETDEWEB)

    Petcu, Cristian; Purcar, Violeta [National Research-Development Institute for Chemistry and Petrochemistry-ICECHIM, Polymer Department, Splaiul Independentei 202, 6th district, 060021, Bucharest (Romania); Ianchiş, Raluca, E-mail: ralumoc@yahoo.com [National Research-Development Institute for Chemistry and Petrochemistry-ICECHIM, Polymer Department, Splaiul Independentei 202, 6th district, 060021, Bucharest (Romania); Spătaru, Cătălin-Ilie; Ghiurea, Marius; Nicolae, Cristian Andi [National Research-Development Institute for Chemistry and Petrochemistry-ICECHIM, Polymer Department, Splaiul Independentei 202, 6th district, 060021, Bucharest (Romania); Stroescu, Hermine [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Splaiul Independentei 202, 060021, Bucharest (Romania); Atanase, Leonard-Ionuţ [University Apollonia, “Acad. Ioan Haulica” Research Institute, Iasi (Romania); Frone, Adriana Nicoleta; Trică, Bogdan; Donescu, Dan [National Research-Development Institute for Chemistry and Petrochemistry-ICECHIM, Polymer Department, Splaiul Independentei 202, 6th district, 060021, Bucharest (Romania)

    2016-12-15

    Highlights: • Si-based polymer is distributed onto the silica surface of sol-gel hybrid films. • FT-IR spectra of sol-gel derived materials confirmed the different chemical structure. • Hydrophobicity increased due to the increasing number of alkyl groups attached to the surface. - Abstract: Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Si−O−Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

  10. Microwave sintering of sol-gel composite films using a domestic microwave oven

    Science.gov (United States)

    Kobayashi, Makiko; Matsumoto, Makoto

    2016-07-01

    Feasibility study of sol-gel composite microwave sintering using a domestic microwave oven was carried out. Two kinds of lead zirconate titanate (PZT) powders were mixed with PZT sol-gel solution and the mixture was sprayed onto 3-mm-thick titanium substrate. The films were sintered by 700 W domestic oven for 10 min. Ultrasonic measurement was carried out in pulse-echo mode and clear multiple echoes were confirmed. It would be suitable method to fabricate high frequency broadband focused ultrasonic transducers. Further research is required to improve sintering degree.

  11. Experiences with sol-gel bonded high porosity alumina fiber materials for filter applications

    OpenAIRE

    Handrick, Karin E.; Mohlratzer, August; Ostertag, Rolf; Sporn, Dieter; Schmidt, Helmut K.

    1988-01-01

    High porous alumina fiber structures appear promising for hot gas filtration in particular for diesel particulate traps. For this purpose, however, a method is required for manufacturing of stable shapes resisant to the blow-out by the gas flow. The sol-gel process was expected to be the best suited method for fiber bonding to provide the required stability. The main tasks of the development-work were a uniform isotropic fiber-distribution, the adaptation of the sol-gel-process to the applica...

  12. Nanoporous titania-coated alumina membranes: sol-gel synthesis and characterisation.

    Science.gov (United States)

    Kermanpur, A; Dastjerdi, V H; Ghassemali, E; Abbasi, M H

    2010-09-01

    In this work, nanoporous titania top layers were deposited by dip-coating process on microporous alpha-alumina substrates using the sol-gel process. The alumina substrates were synthesized by slip casting method using Taguchi optimising approach. The microporous substrate was then used to coat nanoporous titania layers by the sol-gel method. The thickness, pore size, structure and permeability of the membranes were characterised using SEM, XRD, STA and Hg-Porosimetry. The process conditions to achieve defect-free nanoporous titania layers with the average pore size of about 4 nm coated on the microporous alumina substrates with the average pore size of about 270 nm were determined.

  13. 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...

  14. Sol-Gel Deposited Double Layer TiO₂ and Al₂O₃ Anti-Reflection Coating for Silicon Solar Cell.

    Science.gov (United States)

    Jung, Jinsu; Jannat, Azmira; Akhtar, M Shaheer; Yang, O-Bong

    2018-02-01

    In this work, the deposition of double layer ARC on p-type Si solar cells was carried out by simple spin coating using sol-gel derived Al2O3 and TiO2 precursors for the fabrication of crystalline Si solar cells. The first ARC layer was created by freshly prepared sol-gel derived Al2O3 precursor using spin coating technique and then second ARC layer of TiO2 was deposited with sol-gel derived TiO2 precursor, which was finally annealed at 400 °C. The double layer Al2O3/TiO2 ARC on Si wafer exhibited the low average reflectance of 4.74% in the wavelength range of 400 and 1000 nm. The fabricated solar cells based on double TiO2/Al2O3 ARC attained the conversion efficiency of ~13.95% with short circuit current (JSC) of 35.27 mA/cm2, open circuit voltage (VOC) of 593.35 mV and fill factor (FF) of 66.67%. Moreover, the fabricated solar cells presented relatively low series resistance (Rs) as compared to single layer ARCs, resulting in the high VOC and FF.

  15. 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

  16. Production and characterization of LaMnO3 thin films prepared by Sol–Gel technique; Producción y caracterización de láminas delgadas de LaMnO3 preparadas por la técnica de Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Ebeoğlugil, M.F.

    2017-09-01

    In this study, lanthanum manganite (LaMnO3) thin films were prepared by sol-gel method for magnet technology. With this context, precursor solutions with low contact angles were synthesized from all nitrate salts of the respective cations (La, Mn), using ethanol as solvent and acetyl acetone as chelating agents. A dense amorphous film was deposited on silicon (Si) substrate. crystallization of the films was carried out at temperatures between 850 and 1000 °C. The thermal, phase, elemental, microstructural and magnetic properties of the obtained samples were determined by TG/DTA, FTIR, XRD, XPS, SEM and VSM. The results show that sustained perovskite polycrystalline films were grown on the [100]-oriented Si substrates. In addition, the films show ferromagnetic behavior. [Spanish] Se prepararon películas delgadas de manganita de lantano (LaMnO3) mediante el método Sol-gel para la tecnología del imán. Se sintetizaron soluciones precursoras con bajos ángulos de contacto a partir de sales de nitrato de los respectivos cationes (La, Mn), utilizando etanol como disolvente y acetil acetona como agente quelante. Se depositó una película amorfa y densa sobre sustrato de silicio (Si). La cristalización de las láminas se llevó a cabo a temperaturas entre 850 y 1000 ºC. El comportamiento térmico, especies químicas, microestructura y propiedades magnéticas se determinaron mediante TG / DTA, FTIR, XRD, XPS, SEM y VSM respectivamente. Los resultados muestran que láminas policristalinas de perovskita crecieron sobre los sustratos de Si orientados en el plano [100]. Finalmente, las láminas muestran un comportamiento ferromagnético.

  17. Weathering characteristics and moisture uptake properties of wood coated with water-borne sol-gel thin films

    Science.gov (United States)

    M. A. Tshabalala; C. Starr; N. R. Sutherland

    2010-01-01

    In this study, wood specimens were coated with water-borne silsesquioxane oligomers by an in situ sol-gel deposition process. The effect of these water-borne sol-gel thin films on weathering characteristics and moisture-uptake properties of the wood specimens were investigated. The weathering characteristics were investigated by exposure of the specimens to artificial...

  18. 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

  19. Effectiveness of silica based sol-gel microencapsulation method for odorants and flavors leading to sustainable environment.

    Science.gov (United States)

    Ashraf, Muhammad Aqeel; Khan, Aysha Masood; Ahmad, Mushtaq; Sarfraz, Maliha

    2015-01-01

    Microencapsulation has become a hot topic in chemical research. Technology mainly used for control release and protection purposes. The sol-gel micro encapsulation approach for fragrance and aroma in porous silica-based materials leads to sustainable odorant and flavored materials with novel and unique beneficial properties. Sol-gel encapsulation of silica based micro particles considered economically cheap as capital investment in manufacturing is very low and environmentally friendly. Amorphous sol-gel SiO2 is non-toxic and safe, whereas the sol-gel entrapment of delicate chemicals in its inner pores results in pronounced chemical and physical stabilization of the entrapped active agents, thereby broadening the practical utilization of chemically unstable essential oils (EOs). Reviewing progress in the fabrication of diverse odorant and flavored sol-gels, shows us how different synthetic strategies are appropriate for practical application with important health and environmental benefits.

  20. Effect of matrix treatment on spectroscopic properties of HCl catalysed sol-gel glasses containing coumarin laser dyes.

    Science.gov (United States)

    Deshpande, Aparna V; Jathar, Laxman V; Rane, Jayraj R

    2009-07-01

    Coumarin 1, Coumarin 2 and Coumarin 120 are embedded in transparent sol-gel glass samples prepared by sol-gel process using dip method. The sol-gel matrix is given dip treatment with Methanol /Distilled Water (50/50 vol) for 1 to 16 h before dipping into dye solution. The effect of dipping time of matrix in Methanol/ Distilled Water on spectroscopic properties of coumarin dye doped glass samples has been studied. The Optical Density (OD) at absorption maximum wavelength and Fluorescence Intensity (FI) at fluorescence maximum wavelength of all coumarin dyes increase with the time of dipping of the sol-gel sample. These absorption/fluorescence properties of coumarin dyes in sol-gel glass matrices are compared with its respective properties in methanolic solution in acidic environment. The cause of these changes in OD/FI with dipping time is discussed by taking into account the absorption / fluorescence of dye in acidified methanol.

  1. Sulfur dioxide removal by sol-gel sorbent derived CuO/Alumina sorbents in fixed bed adsorber

    Directory of Open Access Journals (Sweden)

    Zhong-Min Wang

    2017-02-01

    Full Text Available Nanostructured alumina supported copper oxide granular sorbents were prepared by the sol-gel method. The properties of the sol-gel derived sorbents were compared with a similar commercial sorbent which has been used in the pilot scale moving-bed copper oxide process for flue gas treatment. The crushing strength of the sol-gel derived sorbents is about 6–7 times that of the commercial samples, while the attrition rate of the former is at least 3 times smaller. At temperatures below 400 °C, SO2 sorption capacity of the sol-gel derived sorbent is about 3 times that of the commercial sorbent with a similar amount of CuO loading (7–9 wt%. The better mechanical properties and higher sulfation capacity of the sol-gel derived alumina supported copper oxide sorbents are due to their unique microstructure and the coating method for CuO.

  2. Effectiveness of silica based sol-gel microencapsulation method for odorants and flavors leading to sustainable environment

    Science.gov (United States)

    Ashraf, Muhammad Aqeel; Khan, Aysha Masood; Ahmad, Mushtaq; Sarfraz, Maliha

    2015-01-01

    Microencapsulation has become a hot topic in chemical research. Technology mainly used for control release and protection purposes. The sol-gel micro encapsulation approach for fragrance and aroma in porous silica-based materials leads to sustainable odorant and flavored materials with novel and unique beneficial properties. Sol-gel encapsulation of silica based micro particles considered economically cheap as capital investment in manufacturing is very low and environmentally friendly. Amorphous sol-gel SiO2 is non-toxic and safe, whereas the sol-gel entrapment of delicate chemicals in its inner pores results in pronounced chemical and physical stabilization of the entrapped active agents, thereby broadening the practical utilization of chemically unstable essential oils (EOs). Reviewing progress in the fabrication of diverse odorant and flavored sol-gels, shows us how different synthetic strategies are appropriate for practical application with important health and environmental benefits. PMID:26322304

  3. Effectiveness of silica based Sol-gel microencapsulation Method for odorants and flavours leading to sustainable Environment

    Science.gov (United States)

    Ashraf, Muhammad Aqeel; Khan, Ayesha Masood; Sarfraz, Maliha; Ahmad, Mushtaq

    2015-08-01

    Microencapsulation has become a hot topic in chemical research. Technology mainly used for control release and protection purposes. The sol-gel micro encapsulation approach for fragrance and aroma in porous silica-based materials leads to sustainable odorant and flavored materials with novel and unique beneficial properties. Sol-gel encapsulation of silica based micro particles considered economically cheap as capital investment in manufacturing is very low and environmentally friendly. Amorphous sol-gel SiO2 is non-toxic and safe, whereas the sol-gel entrapment of delicate chemicals in its inner pores results in pronounced chemical and physical stabilization of the entrapped actives, thereby broadening the practical utilization of chemically unstable essential oils. Reviewing progress in the fabrication of diverse odorant and flavoured sol-gels, shows us how different synthetic strategies are appropriate for practical application with important health and environmental benefits.

  4. The increase in pH during aging of porous sol-gel silica spheres

    NARCIS (Netherlands)

    Titulaer, M.K.; Kegel, W.K.; Jansen, J.B.H.; Geus, John W.

    1994-01-01

    The increase in pH in the hydrothermal fluid is studied after hydrothermal aging of porous silica gel spheres of 1–3 mm diameter. The porous silica spheres are formed by the sol-gel process from a supersaturated silica solution. The increase of the pH of the hydrothermal solution affects the silica

  5. Thermal stability of porous sol-gel phosphosilicates and their surface area stabilisation by lanthanum addition

    NARCIS (Netherlands)

    Falco, Lorena; De Mendonca, Mariana Van Den Tempel; Mercadal, Juan J.; Zarubina, Valeriya; Melián-Cabrera, Ignacio

    2016-01-01

    The thermal stability of porous sol-gel phosphosilicates was studied by comparing the textural features upon calcination between 400 and 550 °C. A significant loss of surface area and pore volume were observed; the first is due to thermal coarsening of the nanoparticles, and the pore volume

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

    Science.gov (United States)

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

    2011-01-01

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

  7. Residual stress fields in sol-gel-derived thin TiO2 layers

    NARCIS (Netherlands)

    Teeuw, D.H.J.; Haas, M. de; Hosson, J.Th.M. De

    1999-01-01

    This paper discusses the induction of residual stresses during the curing process of thin titania layers, which are derived using a sol-gel process. During this process, stresses may build up in the spinning stage, the drying stage, and the consolidation stage. The magnitude and character of these

  8. Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40

    Science.gov (United States)

    Wang, Shengnan; Wang, David K.; Smart, Simon; Diniz da Costa, João C.

    2015-09-01

    A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H2O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification.

  9. Estado del arte del proceso sol-gel en México

    Directory of Open Access Journals (Sweden)

    María Teresa Ramírez Palma

    2010-01-01

    Full Text Available A partir de una revisión bibliográfica, realizada por alumnos de la Maestría en Ciencia e Ingeniería de Materiales de la unam, se muestra el estado del arte del proceso sol-gel en México.

  10. Sol-gel/hydrothermal synthesis of mixed metal oxide of Titanium and ...

    African Journals Online (AJOL)

    Mixed metal oxides of titanium and zinc nanocomposites were prepared through sol-gel method under hydrothermal condition using titanium oxy-(1, 2 - pentadione) and zinc acetate without hazardous additives. The resulting composites were characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscope ...

  11. Analysis of coupled mass transfer and sol-gel reaction in a two-phase system

    NARCIS (Netherlands)

    Castelijns, H.J.; Huinink, H.P.; Pel, L.; Zitha, P.L.J.

    2006-01-01

    The coupled mass transfer and chemical reactions of a gel-forming compound in a two-phase system were studied in detail. Tetra-methyl-ortho-silicate (TMOS) is often used as a precursor in sol-gel chemistry to produce silica gels in aqueous systems. TMOS can also be mixed with many hydrocarbons

  12. 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,

  13. Sol-gel-cum-hydrothermal synthesis of mesoporous Co-Fe ...

    Indian Academy of Sciences (India)

    A combined sol-gel-cum-hydrothermalmethod has been employed to synthesize novelmonometallic (Mn, Fe, Co) and bimetallic (Co-Fe, Mn-Co, Fe-Mn) nanoparticles loaded onto Al₂O₃−MCM-41. Powder XRD, N2 sorption, field emission scanning electron microscopy (FESEM) and high resolution transmission electron ...

  14. Sol-Gel Synthesis of Phosphate-Based Glasses for Hydrophilic Enamel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Sung; Ryu, Bong-ki [Pusan National University, Busan (Korea, Republic of)

    2017-04-15

    In this study, quaternary phosphate-based sol-gel derived glasses were synthesized from a P{sub 2}O{sub 5}-CaO-Na{sub 2}O-TiO{sub 2} system with a high TiO{sub 2} content of up to 50 mol%. The sol-gel method was chosen because incorporating a high percentage of titanium into a phosphate network via traditional melt-quench methods is non-trivial. The structure and thermal properties of the obtained stabilized sol-gel glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The XRD results confirmed the amorphous nature of all of the stabilized sol–gel derived glasses. The FTIR results revealed that added TiO{sub 2} enters the network as (TiO{sub 6}), which likely acts as a modifier oxide. Consequently, the number of terminal oxygen atoms increases, leading to an increase in the number of P-OH bonds. In addition, DSC results confirmed a decrease in glass transition and crystallization temperatures with increasing TiO{sub 2} content. This is the first report of a sol-gel synthesis strategy combined with enameling to prepare glass at low processing temperatures and the first use of such a system for both hydrophilic and chemical resistance purposes.

  15. Optical fiber oxygen sensor based on Pd(II) complex embedded in sol-gel matrix

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Cheng-Shane, E-mail: cschu@mail.mcut.edu.tw [Department of Mechanical Engineering, Ming Chi University of Technology, Taishan Dist., New Taipei City, Taiwan (China)

    2013-03-15

    A simple, low-cost technique for fabrication of high performance optical fiber oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of an optical fiber with ormosil composite xerogel film sequestered with luminophore palladium (II) meso-tetrakis(pentafluorophenyl)porphyrin (PdTFPP) prepared by a sol-gel process. The composite xerogel studied is n-propyltrimethoxysilane (n-propyl-TriMOS)/tetraethylorthosilane (TEOS)/n-Octyltriethoxysilane (Octyl-triEOS). Result shows that, expect for PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogel shows a high sensitivity and linear Stern-Volmer relationship which indicates the homogenous environment of the luminophore. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio I{sub N{sub 2}}/I{sub O{sub 2}}, where I{sub N{sub 2}} and I{sub O{sub 2}} represent the detected phosphorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensor has sensitivity of I{sub N{sub 2}}/I{sub 100O{sub 2}}=263. - Highlights: Black-Right-Pointing-Pointer A simple technique for fabrication of high performance optical fiber oxygen sensor is described. Black-Right-Pointing-Pointer ORMOSIL was produced to serve as a matrix for the fabrication of oxygen sensing film. Black-Right-Pointing-Pointer The optical fiber oxygen sensor has sensitivity of I{sub N{sub 2}}/I{sub 100O{sub 2}}=263. Black-Right-Pointing-Pointer The stable and reproducible signals were obtained with the fiber-optic oxygen sensor.

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-01-01

    NMR investigations on the ORNL process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub l2}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-Gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sub 17}0 NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, ((UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}){sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results show that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an intercalation'' cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ ion exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2}((UO{sub 2}){sub 8}O{sub 4}(OH){sub 10}) {center dot} 8H{sub 2}0. This compound is the precursor to sintered U0{sub 2} ceramic fuel.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-12-31

    NMR investigations on the ORNL process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub l2}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-Gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sub 17}0 NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}]{sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results show that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an ``intercalation`` cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ ion exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2}[(UO{sub 2}){sub 8}O{sub 4}(OH){sub 10}] {center_dot} 8H{sub 2}0. This compound is the precursor to sintered U0{sub 2} ceramic fuel.

  19. Iron specificity of a biosensor based on fluorescent pyoverdin immobilized in sol-gel glass

    Directory of Open Access Journals (Sweden)

    Kisaalita William S

    2011-05-01

    Full Text Available Abstract 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.

  20. Silica/quercetin sol-gel hybrids as antioxidant dental implant materials

    Science.gov (United States)

    Catauro, Michelina; Papale, Ferdinando; Bollino, Flavia; Piccolella, Simona; Marciano, Sabina; Nocera, Paola; Pacifico, Severina

    2015-06-01

    The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing the onset of peri-implant diseases. In this context, quercetin, a naturally occurring flavonoid, has been entrapped at different weight percentages in a silica-based inorganic material by a sol-gel route. The establishment of hydrogen bond interactions between the flavonol and the solid matrix was ascertained by Fourier transform infrared spectroscopy. This technique also evidenced changes in the stretching frequencies of the quercetin dienonic moiety, suggesting that the formation of a secondary product occurs. Scanning electron microscopy was applied to detect the morphology of the synthesized materials. Their bioactivity was shown by the formation of a hydroxyapatite layer on sample surface soaked in a fluid that simulates the composition of human blood plasma. When the potential release of flavonol was determined by liquid chromatography coupled with ultraviolet and electrospray ionization tandem mass spectrometry techniques, the eluates displayed a retention time that was 0.5 min less than quercetin. Collision-activated dissociation mass spectrometry and untraviolet-visible spectroscopy were in accordance with the release of a quercetin derivative. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods, whereas the 2,7-dichlorofluorescein diacetate assay highlighted their ability to inhibit the H2O2-induced intracellular production of reactive oxygen species in NIH-3T3 mouse fibroblast cells. Data obtained, along with data gathered from the MTT cytotoxicity test, revealed that the materials that entrapped the highest amount of quercetin showed notable antioxidant effectiveness.

  1. Sol-gel synthesis and spectrometric structural evaluation of strontium substituted hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, A. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Balossier, G. [INSERM ERM 0203, Laboratoire de Microscopie Electronique Analytique, University of Reims, 21, Rue Clement Ader, 51685 Reims (France); Torres, P.; Michel, J. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Ferreira, J.M.F., E-mail: jmf@cv.ua.pt [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2009-04-30

    Investigations of the electronic structures of substituted strontium apatites were carried out by using X-ray photo electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction technique (XRD) has been used to determine the structural parameters. Electron microprobe microanalysis technique was used to estimate the elemental concentrations in each substituted apatite material. The present work aims at studying the changes in the electronic structure of Sr{sub 5}(PO{sub 4}){sub 3}OH (Sr-HAP) upon isomorphic substitution by F and Cl at the OH site of apatite and Sr by Na at trans Sr-HAP. The ion exchange between Na{sup +} in sodium alginate and aqueous Ca{sup 2+} was important for the preparation of calcium hydroxyapatite. In contrast, the reaction of sodium alginate with the mixture of Na{sub 4}P{sub 2}O{sub 7} and aqueous Sr{sup 2+} afforded strontium hydroxyapatite at the specific ratio. The structure of calcium and strontium phosphates prepared from the sol-gel process evidently depended on the amount of sodium alginate introduced into the mixture of Na{sub 4}P{sub 2}O{sub 7} and the corresponding divalent cations. The findings have ensured that substitution of Sr-HAP by Na enhances the binding energy of O and Sr core levels. It was also noticed that the same substitution decreases the binding energy of P 2s-level. These observations point out to a decrease in the electron density at P and an increase in the electron density at O in Sr atoms.

  2. The crystallization behavior and thermal expansion properties of {beta}-eucryptite prepared by sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Xia Long [School of Material Science and Engineering, Harbin Institute of Technology at Weihai, 2 Wenhua West Road, Weihai 264209 (China); Wen Guangwu, E-mail: wgw@hitwh.edu.cn [School of Material Science and Engineering, Harbin Institute of Technology at Weihai, 2 Wenhua West Road, Weihai 264209 (China); Song Liang; Wang Xinyu [School of Material Science and Engineering, Harbin Institute of Technology at Weihai, 2 Wenhua West Road, Weihai 264209 (China)

    2010-02-15

    Lithium-aluminosilicate glass-ceramics in the form of eucryptite were synthesized through sol-gel technique by mixing boehmite sol, silica sol and lithium salt and sintering at different temperatures for further analysis. Thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), IR analysis and dilatometry were done to study sintering characteristics, phase transformation and thermal expansion behavior on the sintered specimens. XRD and FTIR results confirmed that crystallization of {beta}-eucryptite took place at about 600 deg. C, substantial increase of {beta}-eucryptite was observed in the specimens sintered at temperatures from 800 to 1300 deg. C. Trace amount of cristobalite also emerged at 600 deg. C and disappeared at 1300 deg. C. The thermal expansion behavior characteristics were found to be strongly influenced by crystalline phases in the specimens which depended on the sintering temperatures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Zhenxing; Zhou, Ji; Li, Longtu; Zhang, Hongguo; Gui, Zhilun

    2000-01-01

    A nitrate-citrate gel was prepared from metal nitrates and citric acid by sol-gel process, in order to synthesize Ni{sub 0.25}Cu{sub 0.25}Zn{sub 0.50}Fe{sub 2}O{sub 4} ferrite. The thermal decomposition process was investigated by DTA-TG, IR and XRD techniques. The results revealed that the nitrate-citrate gel exhibits self-propagating combustion behavior. After combustion, the gel directly transformed into single-phase, nano-sized NiCuZn ferrite particles with spinel crystal structure. The synthesized powder can be densified at a temperature lower than 900 deg. C. The sintered body possesses fine-grained microstructure, good frequency stability and high-quality factor compared to the sample prepared by conventional ceramic route.

  4. Structural, textural and morphological characteristics of tannins from Acacia mearnsii encapsulated using sol-gel methods: Applications as antimicrobial agents.

    Science.gov (United States)

    Dos Santos, Cristiane; Vargas, Álvaro; Fronza, Ney; Dos Santos, João Henrique Zimnoch

    2017-03-01

    Tannins from Acacia mearnsii were encapsulated using four different sol-gel methods acid (SGAR), basic (SGBR), silicate (SGSR) and non-hydrolytic (SGNHR) routes. The hybrid materials were analyzed using a set of techniques to characterize their structure, texture and morphology. The antimicrobial performance of the encapsulated materials was evaluated against different microorganisms (Staphylococcus aureus, Escherichia coli, Aspergillus niger and Candida sp.). The data showed that the encapsulation route significantly affects the characteristics of the resulting hybrid materials. Better functional performances were obtained using the silicate route, which produced mesoporous materials with a small surface area (0.96m2g-1) and small particle size (tannins in an aqueous medium and improved their interactions with microorganisms. Furthermore, the process demonstrated the preservation of tannins after synthesis and increased antimicrobial activity (via a controlled tannin release), as demonstrated by the moderate activity against filamentous fungi and yeast. Copyright © 2016. Published by Elsevier B.V.

  5. 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.

  6. Effect of copper doping sol-gel ZnO thin films: physical properties and sensitivity to ethanol vapor

    Science.gov (United States)

    Boukaous, Chahra; Benhaoua, Boubaker; Telia, Azzedine; Ghanem, Salah

    2017-10-01

    In the present paper, the effect of copper doping ZnO thin films, deposited using a sol-gel dip-coating technique, on the structural, optical and ethanol vapor-sensing properties, was investigated. The range of the doping content is 0 wt. %–5 wt. % Cu/Zn and the films’ properties were studied using x-ray diffraction, scanning electron microscopy and a UV–vis spectrophotometer. The obtained results indicated that undoped and copper-doped zinc oxide thin films have polycrystalline wurtzite structure with (1 0 1) preferred orientation. All samples have a smooth and dense structure free of pinholes. A decrease in the band gap with Cu concentration in the ZnO network was observed. The influence of the dopant on ethanol vapor-sensing properties shows an increase in the film sensitivity to the ethanol vapor within the Cu concentration.

  7. Microwave assisted sol-gel synthesis of high dielectric constant CCTO and BFN ceramics for MLC applications

    Directory of Open Access Journals (Sweden)

    Sonia

    2017-06-01

    Full Text Available Ba(Fe1/2Nb1/2O3 (BFN and CaCu3Ti4O12 (CCTO ceramic powders were synthesized by microwave assisted sol-gel synthesis technique and sintered at 1100°C and 1000°C, respectively. Calcination and sintering processes were carried out in a microwave furnace. Dielectric constant (εr~2450 and dielectric loss (tan δ~0.5 at frequency of 1 kHz and 20°C were observed for the BFN ceramic samples. Higher value of εr ~ 3600 and lower value of tan δ ~ 0.07 at frequency of 1 kHz and in 20-60°C temperature range for the CCTO ceramic samples suggested its utility for MLC applications. Sharp decrease of εr and sharp increase of tan δ at higher frequencies of BFN ceramic samples indicated the presence of Debye like relaxation.

  8. Structural Properties and Microstructure of Cobalt Ferrite Particles Synthesized by a Sol-Gel Auto Combustion Method

    Science.gov (United States)

    Raval, Anand; Panchal, Nital; Jotania, Rajshree

    Synthesis and characterization of Cobalt ferrite powders by a sol gel combustion process is focused in the present work. The prepared precursors was calcined at 950° C for 4 hours in order to get cobalt ferrite powder. The effect of metal nitrates/citric acid ratio (referred as x) of CoFe2O4 on structural and micro-structural properties was investigated. The structural characterization on CoFe2O4 ferrite samples were carried out using the X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. Phase identification and crystallite size of calcined powder were determined using XRD analysis. The formation of the ferrite is confirmed by FTIR results. The morphology of prepared CoFe2O4 ferrite samples (with x = 0.5, 1.0, 1.5 and 2.0, where x is metal to citrate ratio) was studied using a scanning electron microscopy.

  9. Effect of vanadium substitution on structural and electrical properties of sol-gel grown nanostructured zinc oxide

    Science.gov (United States)

    Boricha, Hetal; Rajyaguru, Bhargav; Gadani, Keval; Rathod, K. N.; Shrimali, V. G.; Udeshi, Bhagyashree; Keshvani, M. J.; Joshi, A. D.; Pandya, D. D.; Solanki, P. S.; Shah, N. A.

    2017-05-01

    In the present communication, we report the results on the structural and electrical studies on nanostructured pure (ZnO) and Vanadium (V) doped Zn0.95V0.05O samples synthesized using low cost Sol-Gel technique. To understand the structural properties and their dependence on V substitution, X-Ray diffraction (XRD) measurement was carried out for both the samples understudy. XRD results reveal the single phasic wurtzite nature of both the samples showing hexagonal unit cell structure. A minor phase of ZnV2O6 is observed in V doped ZnO sample. Improved dielectric permittivity, enhanced ac conductivity (σac) and suppression in impedance have been discussed on the basis of structural modifications by the substitution of V in ZnO, enhanced charge carrier concentration, charge carrier polarization and correlated barrier hopping due to the localized state.

  10. 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.

  11. Osteoblast behavior on TiO{sub 2} microgrooves prepared by soft-lithography and sol-gel methods

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Lili [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Lu Xiong, E-mail: luxiong_2004@163.com [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China) and Department of Oral Health Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586 (Japan); Leng Yang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Kowloon (Hong Kong); Qu Shuxin; Feng Bo; Weng Jie [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Watari, Fumio [Department of Oral Health Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586 (Japan)

    2012-05-01

    This study focused on the effects of microgrooved TiO{sub 2} surfaces on osteoblast behavior. Microgrooved TiO{sub 2} surfaces with different widths (12 {mu}m and 40 {mu}m) and flat surfaces were fabricated on glass substrates based on the combination of a sol-gel technique and soft-lithography. Osteoblasts (MC3T3-E1) were cultured on the as-prepared microgrooved and flat TiO{sub 2} surfaces. Optical microscopy and scanning electron microscopy were used to analyze the adherent cell behavior by examining the cell morphology. Orientation angle analysis indicated that the cells tended to align along the microgrooves. This tendency was stronger on the microgrooves with smaller widths and became weak with increasing width. Alamar Blue assay indicated that the microgrooves restricted cell proliferation and the alkaline phosphatase assay revealed that the microgrooves limited the differentiation rate. This restriction increased with decreasing microgroove width. The surface energy of the TiO{sub 2} surfaces was size-dependent and followed the order {gamma}{sub 12{mu}m} < {gamma}{sub 40{mu}m} < {gamma}{sub flatsurfaces}. Osteoblast proliferation and differentiation on the surface with high surface energy exhibited high proliferation and differentiation rates. These results indicated that surface energy appeared to be a dominant factor for cell activity. Thus, surface energy would be a valuable index for the cell compatibility of a micropatterned surface. - Highlights: Black-Right-Pointing-Pointer The micropatterned TiO{sub 2} was prepared by soft-lithography and sol-gel technique. Black-Right-Pointing-Pointer TiO{sub 2} microgrooves change the morphology and orientation of osteoblasts. Black-Right-Pointing-Pointer Micropatterns with certain dimensions restrict the activity of osteoblasts. Black-Right-Pointing-Pointer The cell activity is correlated with the surface energies of different substrates.

  12. 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)

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

    Science.gov (United States)

    Aghamohammadi, Sogand; Haghighi, Mohammad; Karimipour, Samira

    2013-07-01

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

  14. Outcome of temperature variation on sol-gel prepared CuO nanostructure properties (optical and dielectric)

    Energy Technology Data Exchange (ETDEWEB)

    Bibi, Maryam [Nano Synthesis Laboratory, Department of Physics, National University of Sciences and Technology, Islamabad (Pakistan); Javed, Qurat-ul-Ain, E-mail: quratulain@sns.nust.edu.pk [Nano Synthesis Laboratory, Department of Physics, National University of Sciences and Technology, Islamabad (Pakistan); Abbas, Hussain [Institute of Avionics & Aeronautics (IAA), Air University, Islamabad (Pakistan); Baqi, Sabah [Nano Synthesis Laboratory, Department of Physics, National University of Sciences and Technology, Islamabad (Pakistan)

    2017-05-01

    The optical and dielectric properties of Copper Oxide (CuO) have made it a fascinating material to be used in solar energy harvesting, gas sensing, optoelectronics and catalytical applications. Focusing on the cost-effectiveness of Sol-gel method, it is employed for nanostructured CuO production. Effect of changing temperature is observed on the formation mechanism of CuO and its properties. The temperature range of 300 °C–500 °C was used in annealing of samples to produce defect free CuO nanomaterial. Prepared material was investigated using phase characterization (X-ray diffraction ‘XRD’) technique, scanning electron microscopy (SEM), UV–Visible absorption spectroscopy and LCR meter. A structural change in prepared CuO was observed from cluster formation to Nano-fibrils by increase in annealing temperature. 11.99 nm–29.17 nm crystallites of CuO were attained by using Debye Scherer formula. A large band gap of 3.15 eV was achieved by increasing the annealing temperature upto 400 °C. For better solar energy harvest, wide band gapped CuO structures are proved to be functional and practical materials. The fabricated CuO nanostructures were found suitable to be used in devices for stabilizing circuit designs for sensitive appliances as well as micro electromechanical systems (mems). - Highlights: • CuO was synthesized by using sol gel method post growth annealing process. • XRD and SEM characterizations confirm the successful synthesis of CuO. • Change in morphology was observed with varying annealing temperature. • Improved optical and dielectric properties were observed.

  15. 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.

  16. {sup 90}Y microspheres prepared by sol-gel method, promising medical material for radioembolization of liver malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Łada, Wiesława, E-mail: w.lada@ichtj.waw.pl [Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Dorodna 16 (Poland); Iller, Edward [National Centre for Nuclear Research, Radioisotope Centre POLATOM, 05-400 Otwock, Andrzej Sołtan 7 (Poland); Wawszczak, Danuta [Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Dorodna 16 (Poland); Konior, Marcin, E-mail: marcin.konior@polatom.pl [National Centre for Nuclear Research, Radioisotope Centre POLATOM, 05-400 Otwock, Andrzej Sołtan 7 (Poland); Dziel, Tomasz [National Centre for Nuclear Research, Radioisotope Centre POLATOM, 05-400 Otwock, Andrzej Sołtan 7 (Poland)

    2016-10-01

    A new technology for the production of radiopharmaceutical {sup 90}Y microspheres in the form of spherical yttrium oxide grains obtained by sol-gel method has been described. The authors present and discuss the results of investigations performed in the development of new production technology of yttrium microspheres and determination of their physic-chemical properties. The final product has the structure of spherical yttrium oxide grains with a diameter 25–100 μm, is stable and free from contaminants. Irradiation of 20 mg samples of grains with diameter of 20–50 μm in the thermal neutron flux of 1.7 × 10{sup 14} cm{sup −2} s{sup −1} at the core of MARIA research nuclear reactor allowed to obtain microspheres labelled with the {sup 90}Y isotope on the way of the nuclear reaction {sup 89}Y(n, γ){sup 90}Y. Specific activity of irradiated microspheres has been determined by application of absolute triple to double coincidence ratio method (TDCR) and has been evaluated at 190 MBq/mg Y. {sup 90}Y microspheres prepared by the proposed technique can be regarded as a promising medical material for radioembolization of liver malignancies. - Highlights: • Sol-gel methods for preparation of spherical yttrium trioxide grains have been proposed. • Determination condition for irradiation {sup 89}Y{sub 2}O{sub 3} grains in nuclear reactor • Evaluation of specific activity of {sup 90}Y microspheres • Estimation of {sup 90}Y microspheres as promising medical material for radioembolization.

  17. All-silica nanofluidic devices for DNA-analysis fabricated by imprint of sol-gel silica with silicon stamp

    DEFF Research Database (Denmark)

    Mikkelsen, Morten Bo Lindholm; Letailleur, Alban A; Søndergård, Elin

    2011-01-01

    We present a simple and cheap method for fabrication of silica nanofluidic devices for single-molecule studies. By imprinting sol-gel materials with a multi-level stamp comprising micro- and nanofeatures, channels of different depth are produced in a single process step. Calcination...... of the imprinted hybrid sol-gel material produces purely inorganic silica, which has very low autofluorescence and can be fusion bonded to a glass lid. Compared to top-down processing of fused silica or silicon substrates, imprint of sol-gel silica enables fabrication of high-quality nanofluidic devices without...

  18. 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.

  19. Pore characterisation and interconnectivity studies on bioactive 58 S sol-gel glass

    Energy Technology Data Exchange (ETDEWEB)

    Cook, R.; Watson, T.; Robinson, P. [Thomas Dental Inst., London (United Kingdom). Microscopy and Imaging Dept.; Fielder, E.; Hench, L.L. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials

    2001-07-01

    The interconnecting pore network of bioactive 58S sol-gel glass is a vital structural characteristic requiring investigation, as in vivo this will provide the route of tissue fluid ingress and ultimately, the sites for early cell proliferation and osteogenesis. To characterise and visualise micropore (<20A) to macropore (>500A) dimension ranges, five complementary analytical methods were applied to 58S sol-gel monoliths, each resolving different characteristics of the pore network. Nitrogen porosimetry best resolved micro and smaller mesopores (20-500A), supplemented by helium ultra-pycnometry data. Mercury intrusion porosimetry was employed to characterise the meso and small macropores. SEM and confocal microscope imaging of the residual mercury within the matrix provided the first visual evidence of pores within the gel-glass interstices. The network's patency was clearly demonstrated by imaging fluorochrome-labelled command-set dental dentine bonding monomers, traversing the matrix. (orig.)

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

    Science.gov (United States)

    1982-01-01

    Containerless melting of glasses in space for the preparation of ultrapure homogeneous glass for optical waveguides is discussed. The homogenization of the glass using conventional raw materials is normally achieved on Earth either by the gravity induced convection currents or by the mechanical stirring of the melt. Because of the absence of gravity induced convection currents, the homogenization of glass using convectional raw materials is difficult in the space environment. Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation.

  1. Tunable erbium-doped microbubble laser fabricated by sol-gel coating

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Xu, Linhua; Ward, Jonathan; Yang, Lan; Chormaic, Síle Nic

    2016-01-01

    In this work, we show that the application of a sol-gel coating renders a microbubble whispering gallery resonator into an active device. During the fabrication of the resonator, a thin layer of erbium-doped sol-gel is applied to a tapered microcapillary, then a microbubble with a wall thickness of 1.3 $\\mu$m is formed with the rare earth diffused into its walls. The doped microbubble is pumped at 980 nm and lasing in the emission band of the Er$^{3+}$ ions with a wavelength of 1535 nm is observed. The laser wavelength can be tuned by aerostatic pressure tuning of the whispering gallery modes of the microbubble. Up to 240 pm tuning is observed with 2 bar of applied pressure. It is shown that the doped microbubble could be used as a compact, tunable laser source. The lasing microbubble can also be used to improve sensing capabilities in optofluidic sensing applications.

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

    Directory of Open Access Journals (Sweden)

    Robert Armon

    2010-03-01

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

  3. Comparative study of ZnO thin films prepared by different sol-gel route

    Directory of Open Access Journals (Sweden)

    F Esmaieli Ghodsi

    2012-03-01

    Full Text Available   Retraction Notice    The paper "Comparative study of ZnO thin films prepared by different sol-gel route" by H. Absalan and F. E. Ghodsi, which appeared in Iranian Journal of Physics Research, Vol. 11, No. 4, 423-428 (in Farsi is translation of the paper "Comparative Study of ZnO Thin Films Prepared by Different Sol-Gel Route" by F. E. Ghodsi and H. Absalan, which appeared in ACTA PHYSICA POLONICA A, Vol 118 (2010 (in English and for this reason is retracted from this journal.The corresponding author  (and also the first author is the only responsible person for this action.   

  4. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    Energy Technology Data Exchange (ETDEWEB)

    Hou Aiqin, E-mail: aiqinhou@dhu.edu.c [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Chen Huawei [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China)

    2010-03-15

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ridhi, R.; Gawri, Isha; Abbas, Saeed J.; Saini, G. S. S.; Tripathi, S. K. [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (INDIA) Fax: +91-172-2783336; Tel.:+91-172-2544362 (India)

    2015-05-15

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

  6. Ultrapure glass optical waveguide: Development in microgravity by the sol gel process

    Science.gov (United States)

    Mukherjee, S. P.; Debsikdar, J. C.; Beam, T.

    1983-01-01

    The sol-gel process for the preparation of homogeneous gels in three binary oxide systems was investigated. The glass forming ability of certain compositions in the selected oxide systems (SiO-GeO2, GeO2-PbO, and SiO2-TiO2) were studied based on their potential importance in the design of optical waveguide at longer wavelengths.

  7. Exploring encapsulation mechanism of DNA and mononucleotides in sol-gel derived silica.

    Science.gov (United States)

    Kapusuz, Derya; Durucan, Caner

    2017-07-01

    The encapsulation mechanism of DNA in sol-gel derived silica has been explored in order to elucidate the effect of DNA conformation on encapsulation and to identify the nature of chemical/physical interaction of DNA with silica during and after sol-gel transition. In this respect, double stranded DNA and dAMP (2'-deoxyadenosine 5'-monophosphate) were encapsulated in silica using an alkoxide-based sol-gel route. Biomolecule-encapsulating gels have been characterized using UV-Vis, (29)Si NMR, FTIR spectroscopy and gas adsorption (BET) to investigate chemical interactions of biomolecules with the porous silica network and to examine the extent of sol-gel reactions upon encapsulation. Ethidium bromide intercalation and leach out tests showed that helix conformation of DNA was preserved after encapsulation. For both biomolecules, high water-to-alkoxide ratio promoted water-producing condensation and prevented alcoholic denaturation. NMR and FTIR analyses confirmed high hydraulic reactivity (water adsorption) for more silanol groups-containing DNA and dAMP encapsulated gels than plain silica gel. No chemical binding/interaction occurred between biomolecules and silica network. DNA and dAMP encapsulated silica gelled faster than plain silica due to basic nature of DNA or dAMP containing buffer solutions. DNA was not released from silica gels to aqueous environment up to 9 days. The chemical association between DNA/dAMP and silica host was through phosphate groups and molecular water attached to silanols, acting as a barrier around biomolecules. The helix morphology was found not to be essential for such interaction. BET analyses showed that interconnected, inkbottle-shaped mesoporous silica network was condensed around DNA and dAMP molecules.

  8. Fractal dimension determination of sol-gel powders using transmission electron microscopy images

    Energy Technology Data Exchange (ETDEWEB)

    Dobrescu, Gianina; Crisan, Maria; Zaharescu, Maria; Ionescu, N.I

    2004-09-15

    SiO{sub 2}, TiO{sub 2} and AlO(OH) powders obtained by the sol-gel method were investigated by transmission electron microscopy. The mass-radius relation was used to determine the fractal dimensions from the images. These fractal dimensions were corrected in order to obtain the powder fractal dimensions. The results indicate a good fractal behavior and high fractal dimensions.

  9. Microstructure of Zirconia-Based Sol-Gel Glasses Studied by SANS

    Czech Academy of Sciences Publication Activity Database

    Ryukhtin, Vasyl; Strunz, Pavel; Kopitsa, G. P.; Ezdakova, K. V.; Gubanova, N. N.; Ivanov, V. K.; Baranchikov, A. Y.; Angelov, Borislav; Feoktistov, A.; Pipich, V.; Levinský, P.

    2015-01-01

    Roč. 128, č. 4 (2015), s. 582-584 ISSN 0587-4246. [ISPMA 13 - 13th INTERNATIONAL SYMPOSIUM ON PHYSICS OF MATERIALS. Praha, 31.08.2014 - 04.09.2014] R&D Projects: GA ČR GB14-36566G; GA MŠk LM2011019 Institutional support: RVO:61389013 ; RVO:61389005 Keywords : sol-gel method * SANS * USANS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.525, year: 2015

  10. Direct measurement of piezoelectric properties of Sol-Gel PZT films

    NARCIS (Netherlands)

    Gardeniers, Johannes G.E.; Verholen, A.G.B.J.; Verholen, A.G.B.J.; Tas, Niels Roelof; Elwenspoek, Michael Curt

    1998-01-01

    PbZr0.53Ti0.47O3 films were deposited on Si-SiO2-Ta-Pt substrates via a conventional sol-gel procedure. Electrical properties of the films were: resistivity ca. 5 × 1011 Ωcm, relative dielectric permittivity 900-1100, remnant polarization ca. 20 μC/cm2, breakdown electric field larger than 50 MV/m.

  11. 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.

  12. Optical chemical sensors based on hybrid organic-inorganic sol-gel nanoreactors.

    Science.gov (United States)

    Tran-Thi, Thu-Hoa; Dagnelie, Romain; Crunaire, Sabine; Nicole, Lionel

    2011-02-01

    Sol-gel porous materials with tailored or nanostructured cavities have been increasingly used as nanoreactors for the enhancement of reactions between entrapped chemical reactants. The domains of applications issued from these designs and engineering are extremely wide. This tutorial review will focus on one of these domains, in particular on optical chemical sensors, which are the subject of extensive research and development in environment, industry and health.

  13. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators

    OpenAIRE

    Roland Himmelhuber; Norwood, Robert A.; Yasufumi Enami; Nasser Peyghambarian

    2015-01-01

    Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator an...

  14. Densification and properties of Sol-Gel derived PZT-fibers for 1-3 composites

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, H.; Sporn, D.; Ullrich, A. [Fraunhofer-Institut fuer Silicatforschung, Wuerzburg (Germany)

    1995-09-01

    The microstructural evolution of sol-gel derived PZT-fibers is strongly dependent on the atmosphere and the T/t-schedule of drying, pyrolysis and sintering. The PbO-partial pressure during sintering plays a key role for grain growth and densification of the PZT-fibers. Fiber density, grain size and the fiber load in the polymer matrix affect the dielectric and ferroelectric properties of the 1-3 composite.

  15. Residual stress fields in sol-gel-derived thin TiO2 layers

    OpenAIRE

    Teeuw, D.H.J.; Haas, M.; De Hosson, J.Th.M.

    1999-01-01

    This paper discusses the induction of residual stresses during the curing process of thin titania layers, which are derived using a sol-gel process. During this process, stresses may build up in the spinning stage, the drying stage, and the consolidation stage. The magnitude and character of these stresses depend heavily on the morphology of the layers in the various stages and the processing conditions. Dried layers are densified using two different processes, conventional furnace heating an...

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

    Science.gov (United States)

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

    2014-11-01

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

  17. Sol-gel Synthesis of a Biotemplated Inorganic Photocatalyst

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng; He, Wen

    2012-01-01

    chemistry and photocatalysis, provides an opportunity to teach valuable laboratory skills and to introduce students to the synthesis, isolation, and characterization of inorganic materials. This laboratory activity is adaptable to a range of educational levels and to various instrumental techniques....

  18. MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

    National Research Council Canada - National Science Library

    Seyed Mohsen Latifi; Mohammadhossein Fathi; Varshosaz Jaleh; Ghochaghi Niloufar

    2015-01-01

    .... In order to improve hydroxyapatite (HA) dissolution rate, in situ apatite-silica nanocomposite powders with various silica contents were synthesized via sol-gel method and mechanisms controlling the Ca ion release from them were investigated...

  19. Mesoporous silica matrices derived from sol-gel process assisted by low power ultrasonic activation

    Directory of Open Access Journals (Sweden)

    Václav Štengl

    2009-06-01

    Full Text Available The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic fi eld, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution – about 90 % of the pores for this sample fall into the mesopore range (2–50 nm. SANS data reveal the formation of primary structural units of sizes around 1.5–2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath.

  20. Sol-gel derived flexible silica aerogel as selective adsorbent for water decontamination from crude oil.

    Science.gov (United States)

    Abolghasemi Mahani, A; Motahari, S; Mohebbi, A

    2017-10-11

    Oil spills are the most important threat to the sea ecosystem. The present study is an attempt to investigate the effects of sol-gel parameters on seawater decontamination from crude oil by use of flexible silica aerogel. To this goal, methyltrimethoxysilane (MTMS) based silica aerogels were prepared by two-step acid-base catalyzed sol-gel process, involving ambient pressure drying (APD) method. To investigate the effects of sol-gel parameters, the aerogels were prepared under two different acidic and basic pH values (i.e. 4 and 8) and varied ethanol/MTMS molar ratios from 5 to 15. The adsorption capacity of the prepared aerogels was evaluated for two heavy and light commercial crude oils under multiple adsorption-desorption cycles. To reduce process time, desorption cycles were carried out by using roll milling for the first time. At optimum condition, silica aerogels are able to uptake heavy and light crude oils with the order of 16.7 and 13.7, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Amperometric detector for gas chromatography based on a silica sol-gel solid electrolyte.

    Science.gov (United States)

    Steinecker, William H; Miecznikowski, Krzysztof; Kulesza, Pawel J; Sandlin, Zechariah D; Cox, James A

    2017-11-01

    An electrochemical cell comprising a silica sol-gel solid electrolyte, a working electrode that protrudes into a gas phase, and reference and counter electrodes that contact the solid electrolyte comprises an amperometric detector for gas chromatography. Under potentiostatic conditions, a current related to the concentration of an analyte in the gas phase is produced by its oxidation at the three-phase boundary among the sol-gel, working electrode, and the gas phase. The sol-gel is processed to contain an electrolyte that also serves as a humidistat to maintain a constant water activity even in the presence the gas chromatographic mobile phase. Response was demonstrated toward a diverse set of analytes, namely hydrogen, 1,2-ethandithiol, phenol, p-cresol, and thioanisole. Using flow injection amperometry of hydrogen with He as the carrier gas, 90% of the steady-state current was achieved in < 1s at a flow rate of 20mLmin(-1). A separation of 1,2-ethandithiol, phenol, p-cresol, and thioanisole at a 2.2mLmin(-1) flow rate was achieved with respective detection limits (k = 3 criterion) of 4, 1, 3, and 70 ppmv when the working electrode potential was 800mV. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Hybrid titanium dioxide/PS-b-PEO block copolymer nanocomposites based on sol-gel synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, J; Tercjak, A; Garcia, I; Peponi, L; Mondragon, I [' Materials-Technologies' Group, Departamento Ingenieria Quimica y Medio Ambiente, Escuela Politecnica, Universidad PaIs Vasco/Euskal Herriko Unibertsitatea, Plaza Europa 1, E-20018 Donostia-San Sebastian (Spain)], E-mail: inaki.mondragon@ehu.es

    2008-04-16

    The poly(styrene)-b-poly(ethylene oxide) (SEO) amphiphilic block copolymer, with two different molecular weights, has been used as a structure directing agent for generating nanocomposites of TiO{sub 2}/SEO via the sol-gel process. SEO amphiphilic block copolymers are designed with a hydrophilic PEO-block which can interact with inorganic molecules, as well as a hydrophobic PS-block which builds the matrix. The addition of different amounts of sol-gel provokes strong variations in the self-assembled morphology of TiO{sub 2}/SEO nanocomposites with respect to the neat block copolymer. As confirmed by atomic force microscopy (AFM), TiO{sub 2}/PEO-block micelles get closer, forming well-ordered spherical domains, in which TiO{sub 2} nanoparticles constitute the core surrounded by a corona of PEO-blocks. Moreover, for 20 vol% sol-gel the generated morphology changes to a hexagonally ordered structure for both block copolymers. The cylindrical structure of these nanocomposites has been confirmed by the two-dimensional Fourier transform power spectrum of the corresponding AFM height images. Affinity between titanium dioxide precursor and PEO-block of SEO allows us to generate hybrid inorganic/organic nanocomposites, which retain the optical properties of TiO{sub 2}, as evaluated by UV-vis spectroscopy.

  3. Enzyme renaturation to higher activity driven by the sol-gel transition: Carbonic anhydrase

    Science.gov (United States)

    Vinogradov, Vladimir V.; Avnir, David

    2015-09-01

    We describe a so-far unknown route for renaturing denatured enzymes, namely subjecting the denatured enzyme to an oxide sol-gel transition. The phenomenon was revealed in a detailed study of denatured carbonic anhydrase which was subjected to an alumina sol-gel transition, up to the thermally stabilizing entrapment in the final xerogel. Remarkably, not only that the killed enzyme regained its activity during the sol-gel process, but its activity increased to 180% of the native enzyme. To the best of our knowledge, this is the first report of enhanced activity following by renaturing (a “Phoenix effect”). Kinetic study which revealed a five-orders of magnitude (!) increase in the Arrhenius prefactor upon entrapment compared to solution. Circular dichroism analysis, differential scanning calorimetry, zeta potential analyses as well as synchronous fluorescence measurements, all of which were used to characterize the phenomenon, are consistent with a proposed mechanism which is based on the specific orienting interactions of the active site of the enzyme with respect to the alumina interface and its pores network.

  4. Sol-gel synthesis and structure of cordierite/tialite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Lachezar Radev

    2009-09-01

    Full Text Available In the present work the results of the research on the sol-gel synthesis and structure of cordierite (2MgO·2Al2O3·5SiO2, tialite (Al2O3·TiO2 and cordierite/tialite glass-ceramics as well cordierite containing 2 wt.% of Co and Co+Cu have been described and discussed. The sol-gel synthesis was carried out using different kind of precursors as follows: Al(NO3×9H2O, Si(OC2H54 , Ti(OC4H94 , Mg(NO32×6H2O, chlorides or nitrates of corresponding metals, H2O, C2H5OH, Aqua Regia, NH4F and PEG. The synthesized gels were dried and thermally treated in the temperature range from 800°C to 1200°C. The sol-gel processes and structure of the cordierite, tialite and cordierite/tialite glass-ceramics have been investigated by means of XRD, FTIR, TEM, SEM and EPMA.

  5. Transparent conductive CuFeO2 thin films prepared by sol-gel processing

    Science.gov (United States)

    Chen, Hong-Ying; Wu, Jia-Hao

    2012-03-01

    In this study, transparent conductive CuFeO2 thin films were deposited onto a quartz substrate using a low-cost sol-gel process and sequential annealing in N2. The sol-gel derived films were annealed at 500 °C for 1 h in air and then annealed at 700 °C in N2 for 2 h. The CuO and CuFe2O4 phases appeared as the film annealed in air, and a single CuFeO2 phase (delafossite, R3m) appeared as the film annealed in N2. X-ray photoelectron spectroscopy showed that the chemical composition of the CuFeO2 thin films was similar to the stoichiometry. The optical bandgap of the CuFeO2 thin films was 3.1 eV. The p-type characteristics of the films were verified by Hall-effect measurements. The electrical conductivity and carrier concentration of the CuFeO2 thin films were 0.358 S cm-1 and 5.34 × 1018 cm-3, respectively. These results show that the proposed low-cost sol-gel process provides a feasible method of depositing transparent CuFeO2 thin films.

  6. Methane combustion of Pd/SiO{sub 2} sol gel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pecchi, G.; Reyes, P.; Concha, I. [Univ. de Concepcion (Chile). Facultad de Ciencias Quimicas; Fierro, J.L.G. [CSIC, Madrid (Spain). Inst. de Catalisis y Petroleoquimica

    1998-10-01

    Surface properties and catalytic activity changes of Pd/SiO{sub 2} catalysts prepared by sol-gel processing have been investigated by evaluating the specific surface area, porosity, metal dispersion, surface acidity, and surface composition. As a comparison, Pd/SiO{sub 2} catalysts prepared by impregnation of SiO{sub 2} obtained by the sol-gel method were also studied. Both series of catalysts were tested in cycles of methane combustion. It has been found that the pH of gelation modifies strongly the porosity and surface area of the catalysts. However, no significant changes were observed in the metal dispersion. XPS results showed that for the catalysts obtained by the sol-gel procedure the Pd/Si surface atomic ratio does not change before or after the combustion cycle. However, in those catalysts prepared by the impregnation method, a significant decrease in the Pd/Si ratio was observed. The catalytic activity in the methane combustion under stoichiometric mixture of diluted CH{sub 4}/O{sub 2} was studied at different temperatures from 473 K up to the temperature required for a total conversion of all the catalysts. It was found that the activity is higher after their use in the catalytic reaction. This behavior is attributed to the presence of Pd{sub {delta}+} species which improve the catalytic activity.

  7. Fabrication and characterization of sol-gel based nanoparticles for drug delivery

    Science.gov (United States)

    Yadav, Reeta

    Nanogels are cross linked polymeric sol-gel based nanoparticles that offer an interior network for incorporation and protection of biomolecules, exhibiting unique advantages for polymer based delivery systems. We have successfully synthesized stable sol-gel nanoparticles by means of [a] silicification reactions using cationic peptides like polylysine as gelating agents, and [b] lyophilization of sol-gels. Macromolecules such as Hemoglobin and Glucose Oxidase and small molecules such as Sodium Nitroprusside (SNP) and antibiotics were encapsulated within the nanogels. We have used transmission electron microscopy, dynamic light scattering, zeta potential analysis, and spectroscopy to perform a physicochemical characterization of the nanogels resulting from the two approaches. Our studies have indicated that the nanogel encapsulated proteins and small molecules remain intact, stable and functional. A Hydrogen Peroxide (H2O2) and Nitric Oxide (NO) generating drug carrier was synthesized using these nanogels and the effect of generation of H2O2 from Glucose Oxidase encapsulated nanogels and NO from SNP encapsulated nanogels was tested on E.coli. The results show that the nanoparticles exert antimicrobial activity against E.Coli, in addition NO generating nanogels potentiated H2O2 generating nanogels induced killing. These data suggest that these NO and H2O2 releasing nanogels have the potential to serve as a novel class of antimicrobials for the treatment of multidrug resistant bacteria. The unique properties of these protein/drug incorporated nanogels raise the prospect of fine tailoring to specific applications such as drug delivery and bio imaging.

  8. Improvement in Tensile Strength of Bamboo Knitted Fabric by Sol-Gel Coating

    Directory of Open Access Journals (Sweden)

    Awais Khatri

    2013-07-01

    Full Text Available Textiles made of bamboo regenerated fibre are reported to have lower tensile strength than the other cellulosic fibres, due to high porosity of the fibre. This paper was aimed to modify the bamboo knitted fabric by the sol-gel coating to improve the tensile strength with minimum effect on its inherent morphology and ultimate relevant properties such as good absorbency and air permeability. The paddry- bake process was employed for the coating where tetraethyl-orthosilicate and nano-titanium-dioxide were used as the active ingredients. The treated fabrics were tested for the tensile behaviour in terms of breaking strength and elongation and the sol-gel process recipe and parameters were optimised. The absorbency, air-permeability and washing durability of the coating were also tested for the optimised process. Results showed the increase in tensile strength of the fabric by sol-gel coating, whereas absorbency and air-permeability were almost unaffected. The coating results were unaffected even after a washing treatment (equivalent to 5 industrial washings. Additionally, the wrinkle recovery angle of the coated fabric was also tested and found improved.

  9. Thin-film silica sol-gels doped with ion responsive fluorescent lipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, D.Y.; Shea, L.E.; Sinclair, M.B.

    1999-01-12

    A metal ion sensitive, fluorescent lipid-b i layer material (5oA PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol-gel immobilization method was quantitative in the entrapment of seif-assembled Iipid-bilayers and yielded thin films for facile configuration to optical fiber piatforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CUCIZ were realized with complete regeneration of the sensor using an ethylenediarninetetraacetic acid (EDTA) solution.

  10. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators

    Directory of Open Access Journals (Sweden)

    Roland Himmelhuber

    2015-07-01

    Full Text Available Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed.

  11. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators.

    Science.gov (United States)

    Himmelhuber, Roland; Norwood, Robert A; Enami, Yasufumi; Peyghambarian, Nasser

    2015-07-27

    Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed.

  12. Determination of Insulator-to-Semiconductor Transition in Sol-Gel Oxide Semiconductors Using Derivative Spectroscopy

    Directory of Open Access Journals (Sweden)

    Woobin Lee

    2015-12-01

    Full Text Available We report a derivative spectroscopic method for determining insulator-to-semiconductor transition during sol-gel metal-oxide semiconductor formation. When an as-spun sol-gel precursor film is photochemically activated and changes to semiconducting state, the light absorption characteristics of the metal-oxide film is considerable changed particularly in the ultraviolet region. As a result, a peak is generated in the first-order derivatives of light absorption (A′ vs. wavelength (λ plots, and by tracing the peak center shift and peak intensity, transition from insulating-to-semiconducting state of the film can be monitored. The peak generation and peak center shift are described based on photon-energy-dependent absorption coefficient of metal-oxide films. We discuss detailed analysis method for metal-oxide semiconductor films and its application in thin-film transistor fabrication. We believe this derivative spectroscopy based determination can be beneficial for a non-destructive and a rapid monitoring of the insulator-to-semiconductor transition in sol-gel oxide semiconductor formation.

  13. 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.

  14. 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.

  15. Sol-Gel SiO2-CaO-P2O5 biofilm with surface engineered for medical application

    Directory of Open Access Journals (Sweden)

    Sonia Regina Federman

    2007-06-01

    Full Text Available Sol-gel film in the SiO2-CaO-P2O5 system was prepared from TEOS, TEP, alcohol and hydrated calcium nitrate in an acidic medium. The coatings were deposited on stainless steel using the dip-coating technique. After deposition, the composite was submitted to heat treatment, at different temperatures and exposure times to investigate the influence of such parameters on the surface morphology of the composite. The coated surfaces were characterized by AFM, SEM and FTIR. The present study showed that the formation of different textures (an important parameter in implant fixation could be controlled by temperature and time of heat treatment.

  16. Sol-gel deposition and plasma treatment of intrinsic, aluminum-doped, and gallium-doped zinc oxide thin films as transparent conductive electrodes

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2015-09-01

    Zinc oxide and aluminum/gallium-doped zinc oxide thin films were deposited via sol-gel spin-coating technique. Employing plasma treatment as alternative to post thermal annealing, we found that the morphologies of these thin films have changed and the sheet resistances have been significantly enhanced. These plasma-treated thin films also show very good optical properties, with transmittance above 90% averaged over the visible wavelength range. Our best aluminum/gallium-doped zinc oxide thin films exhibit sheet resistances (Rs) of ~ 200 Ω/sq and ~ 150 Ω/sq, respectively.

  17. A sol-gel-integrated protein array system for affinity analysis of aptamer-target protein interaction.

    Science.gov (United States)

    Ahn, Ji-Young; Kim, Eunkyung; Kang, Jeehye; Kim, Soyoun

    2011-06-01

    A sol-gel microarray system was developed for a protein interaction assay with high activity. Comparing to 2-dimensional microarray surfaces, sol-gel can offer a more dynamic and broad range for proteins. In the present study, this sol-gel-integrated protein array was used in binding affinity analysis for aptamers. Six RNA aptamers and their target protein, yeast TBP (TATA-binding protein), were used to evaluate this method. A TBP-containing sol-gel mixture was spotted using a dispensing workstation under high-humidity conditions and each Cy-3-labeled aptamer was incubated. The dissociation constants (K(d)) were calculated by plotting the fluorescent intensity of the bound aptamers as a function of the TBP concentrations. The K(d) value of the control aptamer was found to be 8 nM, which agrees well with the values obtained using the conventional method, electric mobility shift assay. The sol-gel-based binding affinity measurements fit well with conventional binding affinity measurements, suggesting their possible use as an alternative to the conventional method. In addition, aptamer affinity measurements by the sol-gel-integrated protein chip make it possible to develop a simple high-throughput affinity method for screening high-affinity aptamers.

  18. Sol-Gel Entrapped Levonorgestrel Antibodies: Activity and Structural Changes as a Function of Different Polymer Formats

    Directory of Open Access Journals (Sweden)

    Moran Shalev

    2011-02-01

    Full Text Available The paper describes development of a sol-gel based immunoaffinity method for the steroid hormone levonorgestrel (LNG and the effects of changes in the sol-gel matrix format on the activity of the entrapped antibodies (Abs and on matrix structure. The best sol-gel format for Ab entrapment was found to be a tetramethoxysilane (TMOS based matrix at a TMOS:water ratio of 1:8, containing 10% polyethylene glycol (PEG of MW 0.4 kDa. Addition of higher percentages of PEG or a higher MW PEG did not improve activity. No activity was obtained with a TMOS:water ratio of 1:12, most likely because of the very dense polymer that resulted from these polymerization conditions. Only minor differences in the non-specific binding were obtained with the various formats. TMOS was found to be more effective than tetrakis (2-hydroxyethylorthosilicate (THEOS for entrapment of anti-levonorgestrel (LNG Abs. However, aging the THEOS-based sol-gel for a few weeks at 4 °C stabilized the entrapped Abs and increased its binding capacity. Confocal fluorescent microscopy with fluorescein isothiocyanate (FITC labeled immunoglobulines (IgGs entrapped in the sol-gel matrix showed that the entrapped Abs were distributed homogenously within the gel. Scanning electron microscopy (SEM images have shown the diverse structures of the various sol-gel formats and precursors.

  19. Molecularly imprinted sol-gel nanofibers based solid phase microextraction coupled on-line with high performance liquid chromatography for selective determination of acesulfame.

    Science.gov (United States)

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-adergani, Behrouz

    2015-03-01

    Sol-gel based molecularly imprinted polymer (MIP) nanofiber was successfully fabricated by electrospinning technique on the surface of a stainless steel bar. The manufactured tool was applied for on-line selective solid phase microextraction (SPME) and determination of acesulfame (ACF) as an artificial sweetener with high performance liquid chromatography (HPLC). The selective ability of method for the extraction of ACF was investigated in the presence of some selected sweeteners such as saccharine (SCH), aspartame (ASP) and caffeine (CAF). Electrospinning of MIP sol-gel solution on the stainless steel bar provided an unbreakable sorbent with high thermal, mechanical, and chemical stability. Moreover, application of the MIP-SPME tool revealed a unique approach for the selective microextraction of the analyte in beverage samples. In this work, 3-(triethoxysilyl)-propylamine (TMSPA) was chosen as a precursor due to its ability to imprint the analyte by hydrogen bonding, Van der Walls, and dipole-dipole interactions. Nylon 6 was also added as a backbone and support for the precursor in which sol could greatly growth during the sol-gel process and makes the solution electrospinable. Various effective parameters in the extraction efficiency of the MIP-SPME tool such as loading time, flow rate, desorption time, selectivity, and the sample volume were evaluated. The linearity for the ACF in beverage sample was in the range of 0.78-100.5 ng mL(-1). Limit of detection (LOD) and quantification (LOQ) were 0.23 and 0.78 ng mL(-1) respectively. The RSD values (n=5) were all below 3.5%at the 20 ng mL(-1) level. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}): Peroxovanadate sol gel synthesis and structural study

    Energy Technology Data Exchange (ETDEWEB)

    Langie da Silva, Douglas, E-mail: douglas.langie@ufpel.edu.br [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Moreira, Eduardo Ceretta [Laboratório de Espectroscopia, Universidade Federal do Pampa, Campus Bagé, Bagé 96400-970 (Brazil); Dias, Fábio Teixeira; Neves Vieira, Valdemar das [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Brandt, Iuri Stefani; Cas Viegas, Alexandre da; Pasa, André Avelino [Laboratório de Filmes Finos e Superfícies, Universidade Federal de Santa Catarina, Caixa Postal 476, Florianópolis 88.040-900 (Brazil)

    2015-01-15

    Nanostructured cobalt vanadium oxide (V{sub 2}O{sub 5}) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH{sub 2}){sub 6}{sup 2+} cations and the (H{sub 2}V{sub 10}O{sub 28}){sup 4−} anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V{sub 2}O{sub 5} gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5}. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed. - Graphical abstract: Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}) nanoribbons synthesized by peroxovanadate sol gel route. - Highlights: • Nanostructured cobalt V{sub 2}O{sub 5} gel spread onto c{sub S}i were synthesized via peroxovanadate sol gel route. • The micro and nanostructure correlates with the cobalt content. • The efficiency of the synthesis route shows to be also dependent of Co content. • The experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5} xerogel.

  1. Properties of Zn O/Cr thin films prepared by Sol-Gel; Propiedades de peliculas delgadas ZnO/Cr preparadas por Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Tirado G, S.; Olvera A, R., E-mail: tirado@esfm.ipn.mx [IPN, Escuela Superior de Fisica y Matematicas, Edificio 9, Unidad Profesional A. L. M., San Pedro Zacatenco, 07788 Mexico D. F. (Mexico)

    2014-08-15

    Zn O films and those superficially modified with chromium were deposited on substrates of soda-lime glass, using the Sol-Gel process and the repeated immersion method. Starting from dehydrated zinc acetate was prepared a solution to 0.6 M to ambient temperature in 2-methoxyethanol and monoethanolamine (Mea) stirring magnetically. The Sol was prepared with an aging to seven days and was used to grow a films group with thickness to eight immersions. These same films were superficially modified with several depositions of a chromium nitrate Sol dissolved in ethanol to low concentration. The Zn O films were structurally characterized by X-ray diffraction, its chemical composition by energy dispersive X-ray spectroscopy and its morphology by scanning electron microscopy and atomic force microscopy, as well as their optical properties by UV-vis. Of the obtained results are proposed possible applications. (author)

  2. Phenyl Functionalized Sol-gel Silica Sorbent for Capillary Microextraction and Chromia-Based Sol-gel Ucon Stationary Phase for Capillary Gas Chromatography

    Science.gov (United States)

    McLean, Michael M.

    The first chapter of this thesis presents an introduction to sol-gel methodology whose usefulness as a synthetic route will be demonstrated with two applications in chromatography. The first application involves the fabrication of a capillary micro-extraction (CME) device by coating a phenyl functionalized extracting phase on the inner surface of a fused silica capillary for analyte pre-concentration. The device was coupled on-line to a RP-HPLC system and practicality was demonstrated using allergens as target analytes. The allergens chosen as model analytes are typically found in fragrance products and food. Most of the 26 fragrance allergens that are monitored by various government authorities have a phenyl organic moiety (a strong chromophore), thus making them appropriate probes for exploring the extraction efficiency of the coating using a UV detector. The CME device showed ppt level limit of detection which makes it suitable for trace analyses of allergens and similar compounds in a variety of matrices. The second application explores the feasibility of using sol-gel derived chromia-based stationary phase in gas chromatographic columns. The organic moiety of the stationary phase was derived from Ucon 75-H-90,000 while the inorganic backbone was prepared using chromium(III) dichloride hydroxide - methacrylic acid - aqua complex, 40% in isopropanol/acetone . Usefulness of prepared chromia-based GC stationary phase was examined for petrochemical application. Promising results were obtained using aliphatic-aromatics, polyaromatic hydrocarbons, BTEX test mixture, cycloalkanes, branched alkanes and akylbenzenes. The column was able to perform without degradation despite being rinsed multiples times sequentially with the following solvents: dichloromethane, methanol, water and finally methanol again. Maximum theoretical plate number calculated is around 2,400 plates/m. The plate number clearly needs improvement but is a promising result for the newly explored

  3. 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.

  4. A new sol-gel synthesis of 45S5 bioactive glass using an organic acid as catalyst.

    Science.gov (United States)

    Faure, J; Drevet, R; Lemelle, A; Ben Jaber, N; Tara, A; El Btaouri, H; Benhayoune, H

    2015-02-01

    In this paper a new sol-gel approach was explored for the synthesis of the 45S5 bioactive glass. We demonstrate that citric acid can be used instead of the usual nitric acid to catalyze the sol-gel reactions. The substitution of nitric acid by citric acid allows to reduce strongly the concentration of the acid solution necessary to catalyze the hydrolysis of silicon and phosphorus alkoxides. Two sol-gel powders with chemical compositions very close to that of the 45S5 were obtained by using either a 2M nitric acid solution or either a 5mM citric acid solution. These powders were characterized and compared to the commercial Bioglass®. The surface properties of the two bioglass powders were assessed by scanning electron microscopy (SEM) and by Brunauer-Emmett-Teller method (BET). The Fourier transformed infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) revealed a partial crystallization associated to the formation of crystalline phases on the two sol-gel powders. The in vitro bioactivity was then studied at the key times during the first hours of immersion into acellular Simulated Body Fluid (SBF). After 4h immersion into SBF we clearly demonstrate that the bioactivity level of the two sol-gel powders is similar and much higher than that of the commercial Bioglass®. This bioactivity improvement is associated to the increase of the porosity and the specific surface area of the powders synthesized by the sol-gel process. Moreover, the nitric acid is efficiently substituted by the citric acid to catalyze the sol-gel reactions without alteration of the bioactivity of the 45S5 bioactive glass. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Synthesis and application of a novel solid-phase microextraction adsorbent: hollow fiber supported carbon nanotube reinforced sol-gel for determination of phenobarbital.

    Science.gov (United States)

    Es'haghi, Zarrin; Rezaeifar, Zohreh; Rounaghi, Gholam-Hossein; Nezhadi, Zahra Alian; Golsefidi, Mazyar Ahmadi

    2011-03-09

    A novel solid-phase microextraction technique using a hollow fiber-supported sol-gel combined with multi-walled carbon nanotubes was employed in the determination of phenobarbital in wastewater. In this new technique, a silica-based, organic-inorganic polymer containing functionalized multi-walled carbon nanotubes (MWCNTs) was prepared with sol-gel technology via the reaction of tetraethylorthosilicate (TEOS) with an acidic catalyst (HCl). This sol was injected into a polypropylene hollow fiber segment for in situ gelation. This device operated in direct immersion sampling mode. The experimental setup is simple and affordable, and the device is disposable, so there is no risk of cross-contamination or carry-over. Parameters affecting extraction such as pH of the aqueous solution, ageing and extraction times, aqueous sample volume, agitation speed and carbon nanotube amount were optimized. Linearity was observed over a range of 0.50-5000 ng mL(-1), with an estimation coefficient (r(2)) higher than 0.982. The limit of detection (LOD) was 0.32 ng mL(-1) (n=5), and repeatability (RSD%=2.9) was from the average of three levels of analyte concentrations (1, 1000 and 4500 ng mL(-1)) with three replicates for each within a single day. Finally, a pre-concentration factor of 2100 was obtained for phenobarbital. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Kinetics of the electrochemically-assisted deposition of sol-gel films.

    Science.gov (United States)

    Liu, Liang; Walcarius, Alain

    2017-06-14

    Electrochemically-assisted deposition is now becoming a widespread method for preparing sol-gel films. It is based on the electrochemical generation of OH - ions, which can then catalyze the sol-gel condensation reactions. It has a key advantage of selectively facilitating the film deposition on electrochemically active surfaces while not affecting the stability of the bulk precursor solution. Experimental studies have clearly shown that the thickness of the electrochemically-assisted deposited films is influenced by the deposition parameters such as the potential and time. However, there is still a lack of quantitative description of the kinetics of film growth due to the complexity of the process. In this preliminary study, we derived quantitative analytical expressions for describing the kinetics associated with the growth of sol-gel films generated by electrochemically assisted deposition. Both heterogeneous and homogeneous condensation reactions were considered. The key strategy was to simplify the process by separating the electrochemical step of generating OH - ions with the condensation steps of film formation under approximation. Furthermore, numerical simulation was carried out to examine the validity and any errors in the analytical expressions in the cases when the required approximations were not fulfilled. The analytical expressions could well explain the trends observed in the experimental studies and could also be used for fitting the experimental results from the literature. This study provides a deeper understanding of the mechanism and quantitative guidance for manipulating electrochemically-assisted deposition processes at a large scale in industry. It may also be referred to in regard to other indirect electrodeposition systems in which the deposition is not an electrochemical step but is instead driven by electrochemically-generated catalysts.

  7. Sol-gel Derived Warfarin - Silica Composites for Controlled Drug Release.

    Science.gov (United States)

    Dolinina, Ekaterina S; Parfenyuk, Elena V

    2017-01-01

    Warfarin, commonly used anticoagulant in clinic, has serious shortcomings due to its unsatisfactory pharmacodynamics. One of the efficient ways for the improvement of pharmacological and consumer properties of drugs is the development of optimal drug delivery systems. The aim of this work is to synthesize novel warfarin - silica composites and to study in vitro the drug release kinetics to obtain the composites with controlled release. The composites of warfarin with unmodified (UMS) and mercaptopropyl modified silica (MPMS) were synthesized by sol-gel method. The composite formation was confirmed by FTIR spectra. The concentrations of warfarin released to media with pH 1.6, 6.8 and 7.4 were measured using UV spectroscopy. The drug release profiles from the solid composites were described by a series of kinetic models which includes zero order kinetics, first order kinetics, the modified Korsmeyer-Peppas model and Hixson-Crowell model. The synthesized sol-gel composites have different kinetic behavior in the studied media. In contrast to the warfarin composite with unmodified silica, the drug release from the composite with mercaptopropyl modified silica follows zero order kinetics for 24 h irrespective to the release medium pH due to mixed mechanism (duffusion + degradation and/or disintegration of silica matrix). The obtained results showed that warfarin - silica sol-gel composites have a potential application for the development of novel oral formulation of the drug with controlled delivery. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  8. Evolution of heterogeneity accompanying sol-gel transitions in a supramolecular hydrogel.

    Science.gov (United States)

    Matsumoto, Yuji; Shundo, Atsuomi; Ohno, Masashi; Tsuruzoe, Nobutomo; Goto, Masahiro; Tanaka, Keiji

    2017-10-18

    When a peptide amphiphile is dispersed in water, it self-assembles into a fibrous network, leading to a supramolecular hydrogel. When the gel is physically disrupted by shaking, it transforms into a sol state. After aging at room temperature for a while, it spontaneously returns to the gel state, called sol-gel transition. However, repeating the sol-gel transition often causes a change in the rheological properties of the gel. To gain a better understanding of the sol-gel transition and its reversibility, we herein examined the thermal motion of probe particles at different locations in a supramolecular hydrogel. The sol obtained by shaking the gel was heterogeneous in terms of the rheological properties and the extent decreased with increasing aging time. This time course of heterogeneity, or homogeneity, which corresponded to the sol-to-gel transition, was observed for the 1st cycle. However, this was not the case for the 2nd and 3rd cycles; the heterogeneity was preserved even after aging. Fourier-transform infrared spectroscopy, small-angle X-ray scattering, and atomic force and confocal laser scanning microscopies revealed that, although the molecular aggregation states of amphiphiles both in the gel and sol remained unchanged with the cycles, the fibril density diversified to high and low density regions even after aging. The tracking of particles with different sizes indicated that the partial mesh size in the high density region and the characteristic length scale of the density fluctuation were smaller than 50 nm and 6 μm, respectively.

  9. 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.

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

    Science.gov (United States)

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

    2016-07-01

    A coating with self-cleaning characteristics has been developed using a TiO2/SiO2 hybrid sol-gel, TiO2 nanoparticles and organosilicate nanoparticles (OSNP). A patented technology of the hybrid sol-gel and OSNP was combined with TiO2 nanoparticles to create the surface chemistry for self-cleaning. Two synthesis methods have been developed to prepare TiO2 nanoparticles (NPs), resulting in the enhancement of local paint by the addition of anatase and rutile TiO2 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 TiO2 NPs in combination with irradiation show a great enhancement of RhB degradation (1%) wt. with a decrease in contact angle and improved washability.

  11. Sol-gel zirconia nanopowders with {alpha}-cyclodextrin as organic additive

    Energy Technology Data Exchange (ETDEWEB)

    Raileanu, M., E-mail: malina_raileanu@yahoo.com [' Ilie Murgulescu' Institute of Physical Chemistry, Roumanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Todan, L., E-mail: ltodan@icf.ro [' Ilie Murgulescu' Institute of Physical Chemistry, Roumanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Crisan, D.; Dragan, N.; Crisan, M.; Stan, C.; Andronescu, C.; Voicescu, M. [' Ilie Murgulescu' Institute of Physical Chemistry, Roumanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Vasile, B.S.; Ianculescu, A. [Department of Oxide Materials Science and Engineering, ' Politehnica' University of Bucharest, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The sol-gel synthesis of a zirconia powder has been performed, in the presence of {alpha}-cyclodextrin as organic additive. Black-Right-Pointing-Pointer A crystalline powder consisting from a mixture of monoclinic and tetragonal zirconia phases has resulted after the thermal treatment. Black-Right-Pointing-Pointer The organic additive acted the role of metal oxides used as doppants for zirconia powders, avoiding phase transformations. Black-Right-Pointing-Pointer The {alpha}-cyclodextrin made particles to assume spherical shape and reach fairly uniform size and prevented their agglomeration. Black-Right-Pointing-Pointer The organic additive led to a certain porous morphology of the zirconia particles that is pores embedded within grains. - Abstract: Nanomaterials present unique structural and physicochemical properties due to their ultra fine size of particles that make them very useful in many domains. The most spectacular applications of nanosized zirconia include ceramics, piezoelectrics, refractories, pigments, solid electrolytes, oxygen sensors, catalysts, ultrafiltration membranes, and chromatography packing materials. Nanostructured zirconia powders can be prepared using various methods, such as sol-gel process, coprecipitation, hydrothermal synthesis, and reverse micelle method. The aim of the present work was to prepare zirconia nanopowders through the sol-gel method, using {alpha}-cyclodextrin as organic additive and to establish its influence on the structural and textural properties of the obtained product. A white, amorphous ZrO{sub 2} powder containing {alpha}-cyclodextrin was prepared, which became a crystalline, stable one, after removing the organic matter by thermal treatment. The resulted nanocrystalline powder contains both monoclinic and tetragonal zirconia phases and is very stable. It presents a relatively reduced tendency of agglomeration of particles and contains closed pores which are embedded in

  12. One- and three-dimensional growth of hydroxyapatite nanowires during sol-gel-hydrothermal synthesis.

    Science.gov (United States)

    Costa, Daniel O; Dixon, S Jeffrey; Rizkalla, Amin S

    2012-03-01

    Nanoscale hydroxyapatite (HA) is an optimal candidate biomaterial for bone tissue engineering because of its bioactive and osteoconductive properties. In this study, micro- and nanoscale HA particles with rod- and wirelike morphology were synthesized by a novel sol-gel-hydrothermal process. Sol-gel chemistry was used to produce a dry gel containing amorphous calcium phosphate (ACP), which was used as a precursor material in a hydrothermal process. The sol-gel-hydrothermal products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to determine particle morphology, crystal structure, and the presence of chemical functional groups. A pure HA crystal was synthesized, which underwent both one- and three-dimensional growth, resulting in tunable microrod and nanorod, and wire morphologies. The effects of solution pH and reaction time on particle diameter and length were assessed. Particle diameter ranged from 25 to 800 nm and decreased with an increase in solution pH, whereas both particle length and diameter increased as the hydrothermal process was prolonged. Nanowire HA powders (10-50 wt %) were mixed with poly(ε-caprolactone) (PCL) to produce PCL/HA composites. Fracture surfaces of PCL/HA composites showed a well-dispersed and homogeneous distribution of HA nanowires within the PCL matrix. Mechanical testing revealed a significant (p < 0.05) increase in the Young's and compressive moduli of PCL/HA composites compared to PCL alone, with 50 wt % HA producing a 3-fold increase in Young's modulus from 193 to 665 MPa and 2-fold increase in compressive modulus from 230 to 487 MPa. These HA nanowires can be used to reinforce polymer composites and are excellent biomaterials for tissue engineering of bone. © 2012 American Chemical Society

  13. 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.

  14. KINETICS OF GRAIN-GROWTH OF YTTRIUM ALUMINUM GARNET FIBERS PREPARED BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Tan H.

    2013-12-01

    Full Text Available The yttrium aluminum garnet (YAG long fibers were prepared by the sol-gel method using aluminum chloride, aluminum powder, yttrium oxide and acetic acid as raw materials. The grain growth law is given by Dn – D0n = Kt (D0 = initial grain size, D = average grain size at time t, n = grain growth exponent and K = reaction constant. The grain growth exponent and activation energy of YAG fibers are ≈ 3 and 200 kJ/mol, respectively. The grain-growth behaviors of YAG were influenced by experimental conditions such as raw materials, initial particle size, initial particle distribution, etc.

  15. Novel Materials through Non-Hydrolytic Sol-Gel Processing: Negative Thermal Expansion Oxides and Beyond

    Directory of Open Access Journals (Sweden)

    Cora Lind

    2010-04-01

    Full Text Available Low temperature methods have been applied to the synthesis of many advanced materials. Non-hydrolytic sol-gel (NHSG processes offer an elegant route to stable and metastable phases at low temperatures. Excellent atomic level homogeneity gives access to polymorphs that are difficult or impossible to obtain by other methods. The NHSG approach is most commonly applied to the preparation of metal oxides, but can be easily extended to metal sulfides. Exploration of experimental variables allows control over product stoichiometry and crystal structure. This paper reviews the application of NHSG chemistry to the synthesis of negative thermal expansion oxides and selected metal sulfides.

  16. Synthesis of CoFe 2O 4 nanowire arrays by sol-gel template method

    Science.gov (United States)

    Ji, Guangbin; Tang, Shaolong; Xu, Baolong; Gu, Benxi; Du, Youwei

    2003-10-01

    CoFe 2O 4 nanowire arrays with an average diameter of about 40 nm were prepared in porous anodic aluminum oxide (AAO) template using sol-gel process. Transmission electron microscopy (TEM) diffraction pattern and X-ray diffraction (XRD) showed that the nanowires were polycrystalline phase. Magnetic measurements showed the arrays of nanowires did not show a preferential magnetic orientation, the reason was briefly discussed. The effect of heating rate on the structure and magnetic properties of CoFe 2O 4 nanowire arrays was investigated. The result showed that the coercivity decreased with the increase of the heating rate.

  17. Preparasi Polimer Hibrid dengan Metode Sol-Gel dan Penerapannya untuk Komponen Mikro-Optik

    Directory of Open Access Journals (Sweden)

    Pina Pitriana

    2016-12-01

    Full Text Available Polimer hibrid merupakan gabungan antara polimer organik dan anorganik. Penggabungan tersebut diharapkan akan menghasilkan sifat unggul dari bahan organik dan anorganik yang dapat dimanfaatkan untuk aplikasi. Polimer hibrid dapat digunakan untuk membuat pola dalam aplikasi mikro optik seperti pandu gelombang. Dalam penelitian ini dibuat variasi film tipis polimer hibrid dengan variasi konsentrasi berat fotoinisiator dan termoinisiator, selain itu dibuat pola pandu gelombang dengan proses fotopolimerisasi. Pembuatan polimer hibrid dilakukan dengan metode sol-gel dan fotopolimerisasi. Proses sol-gel menghasilkan rantai polimer anorganik, sedangkan proses fotopolimerisasi menghasilkan rantai polimer organik. Setelah proses fotopolimerisasi, rantai organik dan anorganik akan berikatan silang (cross-linking. Spektrum reflektansi dari film tipis polimer hibrid sebelum, sesudah fotopolimerisasi dan setelah post-bake terdapat perbedaan fasa gelombang yang menunjukkan perbedaan ketebalan film. Sampel dengan variasi konsentrasi berat Irgacure 819 sebesar 0,3%wt dan 2%wt mengalami penyusutan volume film masing-masing 2,44% dan 4,93%. Sampel dengan penambahan variasi konsentrasi berat Dicumyl peroxide sebesar 1%wt dan 10%wt mengalami penyusutan volume film masing-masing 8,34% dan 5,83%. Pola pandu gelombang dihasilkan dengan proses fotopolimerisasi yang diikuti dengan proses etching, menghasilkan pandu gelombang dengan bentuk struktur kanal persegi yang baik dan tidak terputus-putus. Hal tersebut mengindikasikan proses polimerisasi rantai organik telah berjalan dengan baik dan dapat bertahan setelah dilakukan etching. Hybrid polymer is composite between organic and inorganic polymer. This composite could make good properties from organic and inorganic which can be used for applications. Hybrid polymer can be used as photo-patternable material to produce micro-optical components like waveguide. In this work, weight concentration of photoinitiator and

  18. Characterization of protective sol-gel coatings on magnesium based on phenyl-triethoxysilane precursor

    Energy Technology Data Exchange (ETDEWEB)

    Yekehtaz, M., E-mail: yekehtaz@ca.tu-darmstadt.d [Technische Universitaet Darmstadt, Department of Materials Science, Petersenstr. 23, 64287 Darmstadt (Germany); Sittner, F.; Ugas-Carrion, R.; Flege, S.; Broetz, J.; Ensinger, W. [Technische Universitaet Darmstadt, Department of Materials Science, Petersenstr. 23, 64287 Darmstadt (Germany)

    2010-07-01

    Sol-gel coatings were deposited from a Phenyl-triethoxysilane precursor for corrosion protection on magnesium samples. Film porosity was measured with potentiodynamic scans and the coating's structure was characterized with secondary ion mass spectrometry and X-ray diffraction analysis. At the interface between substrate and coating a magnesium silicate layer was found which was formed by interdiffusion during the deposition process. The coated samples showed a good corrosion resistance and low porosity after heating at comparatively low temperature.

  19. Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating.

    Energy Technology Data Exchange (ETDEWEB)

    Ashley, Carol S.; Rambo, Patrick K.; Schwarz, Jens; Dunphy, Darren Robert; Branson, Eric D.; Smith, Ian Craig; Johnson, William Arthur; Reed, Scott T.; Cook, Adam W.

    2005-03-01

    In order to develop the next generation of high peak intensity lasers, new grating technology providing higher damage thresholds and large apertures is required. The current assumption is that this technical innovation will be multilayer dielectric gratings, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating. A variant of this is explored with the upper grating layer being a lower density gelatin-based volume phase grating in either sol-gel or dichromated gelatin. One key benefit is the elimination of the etching step.

  20. Rheological model for sol-gel phase transition of thermo-aged heavy oil fractions

    Directory of Open Access Journals (Sweden)

    Xiomara Andrea Vargas Arenas

    2010-01-01

    Full Text Available A power-law rheological model is proposed in this paper: G’’ (ω ∼ ωn and G’ (ω ~ ωn. It represents the increased connectivity between thermo-aged asphalt molecules in a rheo-reactor as one of the applications of systematic rheology. The results confirmed a sol-gel phase transition tendency for aged asphalt in the experimental frequency window at temperatures below 40°C. Such pattern could have been related to the structuring effect arising from the thermo-oxidative asphalt aging process during continuous agitation which has been suitably described by the micellar model of asphalt.

  1. Obtention of nanostructured silica glass by sol-gel process with incorporation of lead compounds

    Directory of Open Access Journals (Sweden)

    Ana Maria M. Santos

    1999-07-01

    Full Text Available The methodology of obtention of nanostructured glass, incorporated with lead compounds, obtained by sol-gel processing and the structural characterizations are presented. Specific surface area, porosity, pore morphology and pore size distributions of the gels were characterized with nitrogen sorption (BET and mercury pycnometry. The pore size distributions of gels obtained using lead nitrate were more narrow than the ones observed for gels made with lead acetate. It was also observed the presence of a bimodal pore size distribution for gels produced using lead nitrate.

  2. Tunable Bragg stacks from sol-gel derived Ta2O5 and MEL zeolite films

    Science.gov (United States)

    Gospodinov, B.; Dikova, J.; Mintova, S.; Babeva, T.

    2012-12-01

    In this paper we investigated sol-gel derived Ta2O5 and nanosized MEL zeolite films obtained by spin coating of Tantalum sol and colloidal zeolite solution, respectively. Refractive index and thickness of the films were determined using non-linear curve fitting of measured reflectance spectra. The influence of the post deposition annealing on the optical properties and thickness of the films was studied. Besides tunable Bragg stacks were designed and prepared by layer-by-layer deposition of Ta2O5 and MEL suspensions with quarter-wave thicknesses. The influence of water, acetone and methanol on the optical behavior of Bragg stacks was discussed.

  3. Sol-Gel Synthesis, X-Ray Diffraction Studies, and Electric Conductivity of Sodium Europium Silicate

    Directory of Open Access Journals (Sweden)

    Ekaterina V. Borisova

    2013-01-01

    Full Text Available Sodium europium silicate, NaEu9(SiO46O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4 atoms not related to silicate ions are placed at the centers of Eu(2 triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied.

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

    Science.gov (United States)

    2015-10-19

    Report 3. DATES COVERED (From - To) 1 Jan 2009-31 Jul 2015 4. TITLE AND SUBTITLE Minimally Adhesive , Advanced Non-toxic Coatings of Dendrimeric...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...PD Summary of Research Highlights Supported by ONR N00014-09-1-0217 1) Hydrophobie xerogel coatings are "robust" - good adhesion to glass, aluminum

  5. Effect of preparation conditions in sol-gel method on yellow phosphor with wide spectrum

    Directory of Open Access Journals (Sweden)

    Yenchen Lin

    2017-01-01

    Full Text Available Among several methods to obtain white light in light emitting diodes (LEDs, mixing blue light with yellow light excited by blue light is the most effective and economical method. However, the quality of white light achieved by this method is poor, making it essential to develop high-quality yellow phosphors. In this study, we synthesized yellow phosphors with broad spectral width by the sol-gel method and studied the effect of various synthetic conditions on their photoluminescence spectra. Consequently, we optimized synthesis conditions for a series of yellow phosphors and found that excess europium doping caused quenching and reduced the quantum yield.

  6. Magnetic Characterizations of Sol-Gel-Produced Mn-Doped ZnO

    Directory of Open Access Journals (Sweden)

    R. Asmatulu

    2010-01-01

    Full Text Available Nanoparticles of ZnO doped with 6 at.% Mn were produced by a sol-gel method. X-ray diffraction confirms the hexagonal structure as that of the parent compound ZnO, and high-resolution electron transmission microscopy reveals a single-crystallite lattice. Magnetic measurements using a superconducting quantum interference device indicate that about one half of the Mn2+ ions follow Curie's law for paramagnetism. The remaining Mn2+ ions exhibit a weak ferromagnetic character, which might be induced through canted antiferromagnetic interactions.

  7. Structural phase analysis of a sol-gel nano-crystalline lithium-mica glass-ceramic through different compositions

    Energy Technology Data Exchange (ETDEWEB)

    Tohidifar, M.R., E-mail: tohidifar@znu.ac.ir [Faculty of Engineering, University of Zanjan, P.O. Box 45371-38791, Zanjan (Iran, Islamic Republic of); Alizadeh, P. [Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2016-08-15

    The current paper attempts to study the influence of chemical composition on the phase development of nano-crystalline lithium-mica glass-ceramic. For this purpose, aqueous sol-gel technique was employed to prepare the glass-ceramics. The synthesis process was accomplished using two chemical compositions of Li{sub (1+x)}Mg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6.5x}F{sub 2} and LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} at different x values along with various mass% of MgF{sub 2} inclusion. It was found that considering an optimized amount of MgF{sub 2}, the specimens synthesized through a new formulation of LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} composition are more appropriate for the sol-gel synthesis method, especially because of intensifying the lithium-mica precipitation and also omission of the secondary phase (i.e. lithium aluminum silicate). The results also indicated that any deviation from the optimized amount of MgF{sub 2} (8%) would cause degradation in the intensity of the precipitated lithium-mica, following the nucleation treatment. - Highlights: • Higher intensity of mica phase obtains through LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} composition. • LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} composition offers mica phase without applying excess MgF{sub 2}. • Applying LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} composition leads to omission of minor phases. • Li{sub (1+x)}Mg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6.5x}F{sub 2} formula cannot be useful in mica nucleation process. • Optimum amount of MgF{sub 2} was obtained as 8% following the nucleation process.

  8. Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: dissolution behaviour and biological properties after crystallisation.

    Science.gov (United States)

    Tredwin, Christopher J; Young, Anne M; Abou Neel, Ensanya A; Georgiou, George; Knowles, Jonathan C

    2014-01-01

    Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) were synthesised by the sol-gel method as possible implant coating or bone-grafting materials. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride were incorporated for the preparation of the FHA and FA sol-gels. After heating and powdering the sol-gels, dissolution behaviour was assessed using ion chromatography to measure Ca(2+) and PO4 (3-) ion release. Biological behaviour was assessed using cellular proliferation with human osteosarcoma cells and alamarBlue™ assay. Statistical analysis was performed with a two way analysis of variance and post hoc testing with a Bonferroni correction. Increasing fluoride substitution into an apatite structure decreased the dissolution rate. Increasing the firing temperature of the HA, FHA and FA sol-gels up to 1,000 °C decreased the dissolution rate. There was significantly higher cellular proliferation on highly substituted FHA and FA than on HA or Titanium. The properties of an implant coating or bone grafting material can be tailored to meet specific requirements by altering the amount of fluoride that is incorporated into the original apatite structure. The dissolution behaviour can further be altered by the temperature at which the sol-gel is fired.

  9. Study of Optical Humidity Sensing Properties of Sol-Gel Processed TiO2 and MgO Films

    Directory of Open Access Journals (Sweden)

    B. C. Yadav

    2007-04-01

    Full Text Available Paper reports a comparative study of humidity sensing properties of TiO2 and MgO films fabricated by Sol-gel technique using optical method. One sensing element of the optical humidity sensor presented here consists of rutile structured two-layered TiO2 thin film deposited on the base of an isosceles glass prism. The other sensing element consists of a film of MgO deposited by same technique on base of the prism. Light from He-Ne laser enters prism from one of refracting faces of the prism and gets reflected from the glass-film interface, before emerging out from its other isosceles face. This emergent beam is allowed to pass through an optical fiber. Light coming out from the optical fiber is measured with an optical power meter. Variations in the intensity of light caused by changes in humidity lying in the range 5%RH to 95%RH have been recorded. MgO film shows better sensitivity than TiO2 film.

  10. Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Przybylak, Marcin, E-mail: marcin.przybylak@ppnt.poznan.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Maciejewski, Hieronim, E-mail: maciejm@amu.edu.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland); Dutkiewicz, Agnieszka, E-mail: agdut@interia.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland)

    2016-11-30

    Highlights: • Fabric hydrophobization process using bifunctional silsesquioxanes was studied. • Superhydrophobic fabric was produced using fluorofunctional silsesquioxanes. • Surface of modified fabrics was analyzed using different techniques. - Abstract: The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

  11. Structure and optical properties of rare earth doped Y{sub 2}O{sub 3} waveguide films derived by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Guo, H.; Zhang, W.; Lou, L.; Brioude, A.; Mugnier, J

    2004-06-30

    Pure and rare earth ions doped yttrium oxide (Y{sub 2}O{sub 3}) waveguide films were prepared by a simple sol-gel process and dip-coating technique. Y{sub 2}O{sub 3} were successfully synthesized by hydrolysis of yttrium acetate. The structural evolution of Y{sub 2}O{sub 3} films with annealing temperature was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, waveguide Raman spectroscopy and High-resolution transmission electron microscopy. The propagation loss of Y{sub 2}O{sub 3} thin films at 632.8 nm measured by scattering-detection method is approximately 1.5 dB/cm. The fluorescence of Er{sup 3+} and Eu{sup 3+} doped Y{sub 2}O{sub 3} waveguide thin films were studied under the waveguide configuration. The fluorescence intensities evolution with annealing temperature of Y{sub 2}O{sub 3}:Er{sup 3+} films has been studied and was explained by the multi-phonon non-radiative processes. Our results show that Y{sub 2}O{sub 3} is a good host material for optically active waveguide thin films and sol-gel process is a useful method to derive pure and doped Y{sub 2}O{sub 3} waveguide films.

  12. 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.

  13. Sol-gel synthesis and characterization of SiO2/PCL hybrid materials containing quercetin as new materials for antioxidant implants.

    Science.gov (United States)

    Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando; Piccolella, Simona; Pacifico, Severina

    2016-01-01

    The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing peri-implant disease onset. In this context quercetin, a naturally occurring flavonoid, has been entrapped, at different weight percentages in a silica/poly(ε-caprolactone)-based hybrid material by a sol-gel route. FT-IR and UV spectroscopic techniques were employed in order to characterize the hybrids. FT-IR analysis indicated changes in stretching frequencies of the quercetin dienonic moiety, suggesting that a flavonol oxidized derivative was formed during the sol-gel process. The establishment of hydrogen-bonded interactions between quercetin and silica and polymer matrices,was strongly affected by the amount of polymer. Poly(ε-caprolactone) did not interact with quercetin when it was loaded at high doses (50 wt.%). The morphology of the synthesized materials was observed by using SEM. The obtained images proved that the materials are hybrid nanocomposites. Their bioactivity was shown by the formation of a hydroxyapatite layer on samples' surface soaked in a fluid simulating the composition of the human plasma. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods and their cytotoxicity by the MTT assay. Data obtained revealed that the synthesized materials are biocompatible and that the hybrid system,with 6 wt.% of PCL and 15 wt.% of quercetin, produced the strongest antiradical efficacy.

  14. Effect of ZrN coating by magnetron sputtering and sol-gel processed silica coating on titanium/porcelain interface bond strength.

    Science.gov (United States)

    Xia, Yang; Zhou, Shu; Zhang, Feimin; Gu, Ning

    2011-02-01

    In this study, a coating technique was applied to improve the bond strength of titanium (Ti) porcelain. ZrN coating was prepared by magnetron sputtering, and silica coating was processed by a sol-gel method. The treated surfaces of the specimens were analyzed by X-ray diffraction, and the Ti/porcelain interface was investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy. The coated specimens appeared fully coherent to the Ti substrate. The fractured bonding surface was also investigated by SEM. The residual porcelain on the metal surface could be observed in the ZrN group and silica group, but there was no obvious porcelain remaining in the control group. A three-point-bending test showed that the bonding strength of the ZrN group (45.99 ± 0.65 MPa) was higher than the silica group (37.77 ± 0.78 MPa) (P silica group was significantly higher than the control group (P ceramic surface with ZrN and silica coatings resulted in a stronger Ti/porcelain bond. ZrN coating by magnetron sputtering was a more effective way to improve the bond strength between Ti and porcelain compared with sol-gel processed silica coating in this study.

  15. Zinc oxide films impurified with Ti and prepared by the Sol-gel method; Peliculas de oxido de zinc impurificadas con Ti y preparadas por el metodo Sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Tirado G, S. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Cazares R, J.M.; Maldonado, A. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico)

    2006-07-01

    Titanium-doped zinc oxide thin films have been prepared on silicon substrate using the Sol-Gel technique. The structural, morphology, electrical and optical properties of such thin films were studied as a function of titanium concentration (0.5, 1 and 1.5 %) and the thin films thickness. Zinc acetate dihydrate and titanium (VI)-oxy acetylacetonate were used as precursor materials, using 2-methoxyethanol and monoethanolamine as via. The X-ray diffraction spectra show polycrystalline films in all the cases. It can see for all the thin films a preferential growth along the (002) planes where the titanium concentration and also the thin films thickness play an important rule. No structural changes are observed at all. The surface morphology studied shows as the grain size decreases when thin thickness is increases. For titanium concentration of 0.5, 1 and 1.5 % values the grains size increase also. The thin films thickness for titanium concentration of 1.5 % was 500 nm (4v), 400 nm (3v), 180 nm (2v) and 130 nm (1v), values obtained from cross-section micrographs. Highly resistive samples are obtained for substrate soda-lime even showing high transmittance. Better physical properties are required for gas sensors or semitransparent electrodes and other possible applications. (Author)

  16. Synthesis and characterization of {alpha}-alumina col-gel nanometric: elaboration of biomaterials nanostructured for biomedical applications; Sintese e caracterizacao de alumina-{alpha} sol-gel nanometrica: para elaboracao de biomateriais nanoestruturados para aplicacoes biomedicas

    Energy Technology Data Exchange (ETDEWEB)

    Passoni, L.S.; Feit, G.; Camargo, N.H.A., E-mail: laispassoni@gmail.co [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

    2010-07-01

    The production of nanostructured biomaterials are research themes for these present new characteristics of biocompatibility and bioactivity. The sol-gel process allows obtaining {alpha}-alumina nanometric with purity 99.99%. The use of nanoparticles of Al{sub 2}O{sub 3}-{alpha}, SiO{sub 2} and TiO{sub 2} are being employed as a second stage in the development of nanocomposites biomaterials. The presence of the second phase within a ceramic matrix leads to obtaining nanomaterials with micropores in micro and nanostructures interconnected, what contributes within the processes of osseous integration, osseous induction. The goal of this work focused on synthesis and characterization of an {alpha}- alumina by sol-gel process. Characterization studies were conducted using the various techniques: X-ray diffraction, scanning electron microscopy, exploratory differential scanning calorimetry and infrared spectrometry by Fourier transforms. The preliminary results showed the attainment the nanometric {alpha}-alumina powder. (author)

  17. Preparation and Characterization of Titania-silica Composite Particles by Pechini Sol-gel Method

    Directory of Open Access Journals (Sweden)

    Wu Yuanting

    2016-01-01

    Full Text Available Two Pechini sol-gel processes were used to prepare titania-silica composite particles. The dynamic oxidation behavior of the TiO2-SiO2 powders has been characterized by thermogravimetry-differential scanning calorimetry (TG-DTG-DSC. The crystal phase and microstructure of the composite particles were investigated by X-ray diffraction (XRD and field emission scanning electron microscope (FE-SEM. The effects of Si:Ti molar ratio and sol-gel process on the TiO2-SiO2 powders were studied. The preparation of the polymeric precursors can influence the morphology of obtained TiO2-SiO2 composite particles. The spherical TiO2-SiO2 composite particles which are 20 nm~400 nm in diameter appear in gel-1 system. However, the TiO2-SiO2 powders obtained by gel-2 system are irregular in shape and 2~15 μm in diameter which show a loose porous structure consisted of very fine granules.

  18. Characterization of LiCoO Nanopowders Produced by Sol-Gel Processing

    Directory of Open Access Journals (Sweden)

    Sina Soltanmohammad

    2010-01-01

    Full Text Available LiCoO2 nanopowders, one of the most important cathode materials for lithium-ion batteries, were synthesized via a modified sol-gel process assisted with triethanolamine (TEA as a complexing agent. The influence of three different chelating agents including acrylic acid, citric acid, and oxalic acid on the size and morphology of particles was investigated. Structure and morphology of the synthesized powders were characterized by thermogravimetric/differential thermal analyses (TG/DTA, X-ray diffraction (XRD, and transmission electron microscopy (TEM. Results indicate that the powder processed with TEA and calcinated at 800∘C had an excellent hexagonal ordering of -NaFeO2-type (space group R3m. Also, the other three complexing agents had a decisive influence on the particle size, shape, morphology, and degree of agglomeration of the resulting oxides. Based on the data presented in this work, it is proposed that the optimized size and distribution of LiCoO2 powders may be achieved through sol-gel processing using TEA as a chelating agent.

  19. Biocompatibility of sol-gel-derived titania-silica coated intramedullary NiTi nails.

    Science.gov (United States)

    Muhonen, V; Kujala, S; Vuotikka, A; Aäritalo, V; Peltola, T; Areva, S; Närhi, T; Tuukkanen, J

    2009-02-01

    We investigated bone response to sol-gel-derived titania-silica coated functional intramedullary NiTi nails that applied a continuous bending force. Nails 26 mm in length, either straight or with a radius of curvature of 28 or 15 mm, were implanted in the cooled martensite form from a proximal to distal direction into the medullary cavity of the right femur in 40 Sprague-Dawley rats. Body temperature restored the austenite form, causing the curved implants to generate a bending force on the bone. The femurs were examined after 24 weeks. Bone length measurements did not reveal any bowing or shortening of the bone in the experimental groups. The results from histomorphometry demonstrated that the stronger bending force, together with sol-gel surface treatment, resulted in more bone deposition around the implant and the formation of significantly less fibrous tissue. Straight intramedullary nails, even those with a titania-silica coating, were poorly attached when compared to the implants with a curved austenite structure.

  20. Phospholipid Fatty Acids as Physiological Indicators of Paracoccus denitrificans Encapsulated in Silica Sol-Gel Hydrogels

    Science.gov (United States)

    Trögl, Josef; Jirková, Ivana; Kuráň, Pavel; Akhmetshina, Elmira; Brovdyová, Tat′jána; Sirotkin, Alexander; Kirilina, Tatiana

    2015-01-01

    The phospholipid fatty acid (PLFA) content was determined in samples of Paracoccus denitrificans encapsulated in silica hydrogel films prepared from prepolymerized tetramethoxysilane (TMOS). Immediately after encapsulation the total PLFA concentration was linearly proportional to the optical density (600 nm) of the input microbial suspension (R2 = 0.99). After 7 days this relationship remained linear, but with significantly decreased slope, indicating a higher extinction of bacteria in suspensions of input concentration 108 cells/mL and higher. trans-Fatty acids, indicators of cytoplasmatic membrane disturbances, were below the detection limit. The cy/pre ratio (i.e., ratio of cyclopropylated fatty acids (cy17:0 + cy19:0) to their metabolic precursors (16:1ω7 + 18:1ω7)), an indicator of the transition of the culture to a stationary growth-phase, decreased depending on co-immobilization of nutrients in the order phosphate buffer > mineral medium > Luria Broth rich medium. The ratio, too, was logarithmically proportional to cell concentration. These results confirm the applicability of total PLFA as an indicator for the determination of living biomass and cy/pre ratio for determination of nutrient limitation of microorganisms encapsulated in sol-gel matrices. This may be of interest for monitoring of sol-gel encapsulated bacteria proposed as optical recognition elements in biosensor construction, as well as other biotechnological applications. PMID:25690547

  1. 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.

  2. Giant phase transition properties at terahertz range in VO₂ films deposited by sol-gel method.

    Science.gov (United States)

    Shi, Qiwu; Huang, Wanxia; Zhang, Yaxin; Yan, Jiazhen; Zhang, Yubo; Mao, Mao; Zhang, Yang; Tu, Mingjing

    2011-09-01

    VO(2) films were fabricated on high-purity single-crystalline silicon substrate by the sol-gel method, followed by rapid annealing. The composition and microstructure of the films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The results indicated a polycrystalline nature with high crystallinity and compact nanostructure for the films, and the concentration of +4 valence vanadium is 79.85%. Correlated with these, a giant transmission modulation ratio about 81% of the film was observed by terahertz time domain spectroscopy. The experimentally observed transmission characteristics were reproduced approximately, by a simulation at different conductivities across the phase transition. According to the effective-medium theory, we assumed that it is important to increase the concentration of +4 valence vanadium oxide phases and improve the compactness of the VO(2) films for giant phase transition properties. The sol-gel-derived VO(2) films with giant phase transition properties at terahertz range, and the study on their composition and microstructure, provide considerable insight into the fabrication of VO(2) films for the application in THz modulation devices.

  3. New optical fiber type: microporous sol-gel-clad optical fibers

    Science.gov (United States)

    Skutnik, Bolesh J.

    1999-04-01

    A new type of optical fiber has been developed. It is made with all pure silica in both the core and cladding. This is possible because the cladding is a micro porous silica produced by a modified sol-gel technology. The formation and characteristics of this new optical fiber type are described. In particular the optical and mechanical properties are illustrated and described. The strength and fatigue of these optical fibers are very good, even without additional protective jackets. Unjacketed fibers have mean Weibull strengths in bending of 6.5 to 7.6 GPa with Weibull slopes in the 40 to 60 range. Fatigue results for fibers tested in ambient air, ambient water and boiling water are presented. The dynamic and static fatigue parameters are around 20. The micro porous structure of the sol-gel cladding provides sites for attaching different moieties which could activate biochemical reactions or be useful as sensing sites. Based on preliminary experiments, some possibilities are presented. In general this new structure can provide opportunities for as yet unidentified applications where chemicals and or light must be brought in close contact with body tissue to effect beneficial reactions there.

  4. Development of sol-gel bioactive glass for hard tissue regeneration

    Science.gov (United States)

    Noor, Siti Noor Fazliah Mohd; Zain, Nurul Shazwani Mohd; Wei, Poh Yong; Azizan, Nur Syazana; Mohamad, Hasmaliza

    2016-12-01

    The regeneration of hard tissues requires various contributing factors such as cells, scaffolds and growth factors. Bioactive glasses are known for its properties to stimulate hard tissue regeneration. In this study, sol-gel bioactive glasses (BG) were prepared and characterized. Sol-gel BG powders having particle size less than 25 µm were incubated with cell culture medium for 4 hours at 37°C on continuous rolling, and then the medium was filtered using 0.22 µm syringe filters. Prior to use, the SGBG-conditioned media were supplemented with 10% (v/v) fetal bovine serum and 1% (v/v) antibiotic-antimycotic, and were allowed to equilibrate overnight inside a CO2 incubator. The human dental pulp stem cells (DPSC) were incubated with the BG-conditioned media and their viability and proliferation were assessed at day 1, 2, 4 and 7 using Alamar Blue and MTT assays. The results showed that BG at various powders to liquid ratio concentrations promoted DPSC growth. The BG have potential to be used for hard tissue regeneration especially in the field of regenerative dentistry.

  5. Phospholipid Fatty Acids as Physiological Indicators of Paracoccus denitrificans Encapsulated in Silica Sol-Gel Hydrogels

    Directory of Open Access Journals (Sweden)

    Josef Trögl

    2015-02-01

    Full Text Available The phospholipid fatty acid (PLFA content was determined in samples of Paracoccus denitrificans encapsulated in silica hydrogel films prepared from prepolymerized tetramethoxysilane (TMOS. Immediately after encapsulation the total PLFA concentration was linearly proportional to the optical density (600 nm of the input microbial suspension (R2 = 0.99. After 7 days this relationship remained linear, but with significantly decreased slope, indicating a higher extinction of bacteria in suspensions of input concentration 108 cells/mL and higher. trans-Fatty acids, indicators of cytoplasmatic membrane disturbances, were below the detection limit. The cy/pre ratio (i.e., ratio of cyclopropylated fatty acids (cy17:0 + cy19:0 to their metabolic precursors (16:1ω7 + 18:1ω7, an indicator of the transition of the culture to a stationary growth-phase, decreased depending on co-immobilization of nutrients in the order phosphate buffer > mineral medium > Luria Broth rich medium. The ratio, too, was logarithmically proportional to cell concentration. These results confirm the applicability of total PLFA as an indicator for the determination of living biomass and cy/pre ratio for determination of nutrient limitation of microorganisms encapsulated in sol-gel matrices. This may be of interest for monitoring of sol-gel encapsulated bacteria proposed as optical recognition elements in biosensor construction, as well as other biotechnological applications.

  6. Microalgae fiber optic biosensors for herbicide monitoring using sol-gel technology.

    Science.gov (United States)

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

    2009-08-15

    Three microalgal species (Dictyosphaerium chlorelloides (D.c.), Scenedesmus intermedius (S.i.) and Scenedesmus sp. (S.s.)) were encapsulated in silicate sol-gel matrices and the increase in the amount of chlorophyll fluorescence signal was used to quantify simazine. Influence of several parameters on the preparation of the sensing layers has been evaluated: effect of pH on sol-gel gelation time; effect of algae density on sensor response; influence of glycerol (%) on the membrane stability. Long term stability was also tested and the fluorescence signal from biosensors remained stable for at least 3 weeks. D.c. biosensor presented the lowest detection limits for simazine (3.6 microg L(-1)) and the broadest dynamic calibration range (19-860 microg L(-1)) with IC(50) 125+/-14 microg L(-1). Biosensor was validated by HPLC with UV/DAD detection. The biosensor showed response to those herbicides that inhibit the photosynthesis at photosystem II (triazines: simazine, atrazine, propazine, terbuthylazine; urea based herbicides: linuron). However, no significant increases of fluorescence response was obtained for similar concentrations of 2,4-D (hormonal herbicide) or Cu(II). The combined use of two biosensors that use two different genotypes, sensitive and resistant to simazine, jointly allowed improving microalgae biosensor specificity.

  7. Fabrication and Crystal Structure of Sol-Gel Deposited BST Thin Films with Compositional Gradient

    Directory of Open Access Journals (Sweden)

    Czekaj D.

    2017-06-01

    Full Text Available In the present research technology of compositionally graded barium strontium titanate Ba1-xSrxTiO3 thin films deposited on stainless steel substrates by sol-gel spin coating followed with thermal annealing at T = 650°C is reported. Results of thermal behavior of the sol-gel derived powders with compositions used for fabrication of graded structure (i.e. with Sr mole fraction x = 0.5, 0.4 and 0.3 are described. X-ray diffraction studies of the phase composition and crystal structure of such complex thin film configuration are given. It was found that gel powders exhibited a large total weight loss of about Δm ≈ 44-47%. Three stages of weight loss took place at temperature ranges: below T ≈ 300°C, at ΔT ≈ 300-500°C and between T = 600°C and T = 800°C. Phase analysis has shown that the dominating phase is Ba0.67Sr0.33TiO3 compound while the second phase is Ba0.7Sr0.3TiO3 or Ba0.5Sr0.5TiO3 for “up-graded” and “down-graded” structure, respectively.

  8. 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.

  9. Sol-Gel Behavior of Hydroxypropyl Methylcellulose (HPMC) in Ionic Media Including Drug Release.

    Science.gov (United States)

    Joshi, Sunil C

    2011-10-24

    Sol-gel transformations in HPMC (hydroxypropyl methylcellulose) are being increasingly studied because of their role in bio-related applications. The thermo-reversible behavior of HPMC is particularly affected by its properties and concentration in solvent media, nature of additives, and the thermal environment it is exposed to. This article contains investigations on the effects of salt additives in Hofmeister series on the HPMC gelation. Various findings regarding gelation with salt ions as well as with the ionic and non-ionic surfactants are presented. The gel formation in physiological salt fluids such as simulated gastric and intestine fluids is also examined with the interest in oral drug delivery systems. The processes of swelling, dissolution and dispersion of HPMC tablets in simulated bio-fluids are explored and the release of a drug from the tablet affected by such processes is studied. Explanations are provided based on the chemical structure and the molecular binding/association of HPMC in a media. The test results at the body or near-body temperature conditions helped in understanding the progress of the gelation process within the human body environment. The detailed interpretation of various molecule level interactions unfolded the sol-gel mechanisms and the influence of a few other factors. The obtained test data and the established mathematical models are expected to serve as a guide in customizing applications of HPMC hydrogels.

  10. Diameter deviation calculation for UO{sub 2} kernel by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Guo Wenli; Xing Juan [Beijing Key Lab of Fine Ceramics, Institution of Nuclear and New Energy Technology, Tsinghua University, Beijing 10084 (China); Liang, T.X., E-mail: txliang@tsinghua.edu.cn [Beijing Key Lab of Fine Ceramics, Institution of Nuclear and New Energy Technology, Tsinghua University, Beijing 10084 (China); Jin Xin [CNNC China Nuclear Power Engineering Co. Ltd., Beijing 100840 (China)

    2011-08-15

    Highlights: > UO{sub 2} kernels are produced by a sol-gel method. > The formula about jet velocity, solution level and gas pressure on solution was established. > The decline of solution level leads to the decreasing of jet velocity and the solution mass flow rate, as a result, the diameter deviation increased. > After compensating the pressure on the liquid gradually during the casting process, the standard deviation of kernel diameter was less than 12 {mu}m. - Abstract: UO{sub 2} kernels for HTR (High Temperature Gas-cooled Reactor) fuel element are produced using a sol-gel method. The size of UO{sub 2} kernels was controlled strictly by minimizing the dispersion of the UO{sub 2} kernel diameter during the casting process. A relationship between the filling gas tank pressure and solution level in the tank was developed to keep a constant solution mass flow rate in the nozzles. Based on equation of flow energy conservation, a formula about jet velocity, solution level and gas tank pressure on solution was established. Using the formula, the minimum pressure and maximum pressure were calculated. During the casting process, the decline of solution level will lead to the decreasing of jet velocity and the solution mass flow rate that can cause the increasing of diameter deviation. By compensating the pressure on the liquid gradually during the casting process, the flow fluency was kept in an acceptable range stably, the standard deviation of kernel diameter was less than 12 {mu}m.

  11. Sol-Gel Derived Eu3+-Doped Gd2Ti2O7 Pyrochlore Nanopowders

    Directory of Open Access Journals (Sweden)

    Sanja Ćulubrk

    2015-01-01

    Full Text Available Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7 pyrochlore nanopowders. According to Gd2Ti2O7 precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7 nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ ions concentration shows that Gd2Ti2O7 host can accept Eu3+ ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (~2.7 ms and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+. Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.

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

    Science.gov (United States)

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

    2017-03-01

    Titania-Hydroxyapatite (TiO2/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: TiO2/HAP composite and TiO2/HAP bilayer. Physicochemical characterization highlighted the bioactivity response of the TiO2/HAP composite once incubated in physiological conditions for 7days whereas the TiO2/HAP bilayer showed instability and dissolution. Biological analysis revealed a failure in human stem cells adhesion on TiO2/HAP bilayer whereas on TiO2/HAP composite the presence of polygonal shaped cells, possessing good behaviour attested a good biocompatibility of the composite coating. Finally, TiO2/HAP composite with hardness up to 0.6GPa and elastic modulus up to 18GPa, showed an increased corrosion resistance of 316L SS. In conclusion, the user-friendly sol-gel processes led to bioactive TiO2/HAP composite buildup suitable for biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Sol-gel Process in Preparation of Organic-inorganic Hybrid Materials

    Directory of Open Access Journals (Sweden)

    Macan, J

    2008-07-01

    Full Text Available Organic-inorganic hybrid materials are a sort of nanostructured material in which the organic and inorganic phases are mixed at molecular level. The inorganic phase in hybrid materials is formed by the sol-gel process, which consists of reactions of hydrolysis and condensation of metal (usually silicon alkoxides. Flexibility of sol-gel process enables creation of hybrid materials with varying organic and inorganic phases in different ratios, and consequently fine-tuning of their properties. In order to obtain true hybrid materials, contact between the phases should be at molecular level, so phase separation between thermodynamically incompatible organic and inorganic phases has to be prevented. Phase interaction can be improved by formation of hydrogen or covalent bonds between them during preparation of hybrid materials. Covalent bond can be introduced by organically modified silicon alkoxides containing a reactive organic group (substituent capable of reacting with the organic phase. In order to obtain hybrid materials with desired structures, a detailed knowledge of hydrolysis and condensation mechanism is necessary. The choice of catalyst, whether acid or base, has the most significant influence on the structure of the inorganic phase. Other important parameters are alkoxide concentration, water: alkoxide ratio, type of alkoxide groups, solvent used, temperature, purity of chemicals used, etc. Hydrolysis and condensation of organically modified silicon alkoxides are additionally influenced by nature and size of the organic supstituent.

  14. Sol-Gel Behavior of Hydroxypropyl Methylcellulose (HPMC in Ionic Media Including Drug Release

    Directory of Open Access Journals (Sweden)

    Sunil C. Joshi

    2011-10-01

    Full Text Available Sol-gel transformations in HPMC (hydroxypropyl methylcellulose are being increasingly studied because of their role in bio-related applications. The thermo-reversible behavior of HPMC is particularly affected by its properties and concentration in solvent media, nature of additives, and the thermal environment it is exposed to. This article contains investigations on the effects of salt additives in Hofmeister series on the HPMC gelation. Various findings regarding gelation with salt ions as well as with the ionic and non-ionic surfactants are presented. The gel formation in physiological salt fluids such as simulated gastric and intestine fluids is also examined with the interest in oral drug delivery systems. The processes of swelling, dissolution and dispersion of HPMC tablets in simulated bio-fluids are explored and the release of a drug from the tablet affected by such processes is studied. Explanations are provided based on the chemical structure and the molecular binding/association of HPMC in a media. The test results at the body or near-body temperature conditions helped in understanding the progress of the gelation process within the human body environment. The detailed interpretation of various molecule level interactions unfolded the sol-gel mechanisms and the influence of a few other factors. The obtained test data and the established mathematical models are expected to serve as a guide in customizing applications of HPMC hydrogels.

  15. Combining inkjet printing and sol-gel chemistry for making pH-sensitive surfaces.

    Science.gov (United States)

    Orsi, Gianni; De Maria, Carmelo; Montemurro, Francesca; Chauhan, Veeren M; Aylott, Jonathan W; Vozzi, Giovanni

    2015-01-01

    Today biomedical sciences are experiencing the importance of imaging biological parameters with luminescence methods. Studying 2D pH distribution with those methods allows building knowledge about complex cellular processes. Immobilizing pH sensitive nanoparticles inside hydrogel matrixes, in order to guarantee a proper SNR, could easily make stable and biocompatible 2D sensors. Inkjet printing is also well known as tool for printing images onto porous surfaces. Recently it has been used as a free-form fabrication method for building three-dimensional parts, and now is being explored as a way of printing electrical and optical devices. Inkjet printing was used either as a rapid prototyping method for custom biosensors. Sol-gel method is naturally bound with inkjet, because the picoliter-sized ink droplets evaporate quickly, thus allowing quick sol-gel transitions on the printed surface. In this work will be shown how to merge those technologies, in order to make a nanoparticles doped printable hydrogel, which could be used for making 2D/3D smart scaffolds able to monitor cell activities. An automated image analysis system was developed in order to quickly have the pH measurements from pH nanosensors fluorescence images.

  16. Hydroxyapatite Coating on TiO₂ Nanotube by Sol-Gel Method for Implant Applications.

    Science.gov (United States)

    Lim, Hyun-Pil; Park, Sang-Won; Yun, Kwi-Dug; Park, Chan; Ji, Min-Kyung; Oh, Gye-Jeong; Lee, Jong-Tak; Lee, Kwangmin

    2018-02-01

    The aim of this study was to determine the effect of hydroxyapatite (HA) coating on titanium dioxide (TiO2) nanotube by sol-gel process on viability of osteoblast like cell (MC3T3-E1) and bone formation in rat tibia. Specimens were divided into three groups including commercially pure titanium (control group), TiO2 nanotubes (group N), and HA coated TiO2 nanotubes (group HN). Surface characteristics were determined using field emission scanning electron microscope (FE-SEM; S-4700, Hitachi, Japan) and contact angles were measured. Cell viability was investigated in vitro after 1 day, 3 days, and 7 days of incubation. Implants (2.0 mm in diameter and 5.0 mm in length) were inserted into the tibia of rats. After 4 weeks, histomorphometric analysis was performed. Both N and HN groups showed enhanced hydrophilicity compared to control group. After 7 days of implantation, group HN showed higher cell viability with marginal significance (0.05 < P < 0.1). Bone to implant contact (BIC) ratio in the control group, group N, and group HN were 32.5%, 33.1%, and 43.8%, respectively. Results of this study showed that HA coated TiO2 nanotube using sol-gel process could be used to enhance hydrophilicity and improve osseointegration of dental implant surface.

  17. Synthesis of ZnO-CuO Nanocomposite Aerogels by the Sol-Gel Route

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    Rula M. Allaf

    2014-01-01

    Full Text Available The epoxide addition sol-gel method has been utilized to synthesize porous zinc-copper composite aerogels in the zinc-to-copper molar ratios of 50 : 50 to 90 : 10. A two-step mixing approach has been employed to produce aerogels composed of nano- to micrometer sized particles. The aerogels were characterized by ultrahigh resolution scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. The as-synthesized aerogels had a thin flake- or petal-like microstructure comprised of clustered flakes on two size scales; they were identified as being crystalline with the crystalline species identified as copper nitrate hydroxide, zinc hydroxide chloride hydrate, and zinc hydroxide nitrate hydrate. Annealing of the aerogel materials at a relatively low temperature (400°C resulted in a complete phase transition of the material to give highly crystalline ZnO-CuO aerogels; the aerogels consisted of networked nanoparticles in the ~25–550 nm size range with an average crystallite size of ~3 nm and average crystallinity of 98%. ZnO-CuO aerogels are of particular interest due to their particular catalytic and sensing properties. This work emphasizes the versatility of this sol-gel route in synthesizing aerogels; this method offers a possible route for the fabrication of aerogels of different metal oxides and their composites.

  18. Surface Modification of Zirconia Substrate by Calcium Phosphate Particles Using Sol-Gel Method.

    Science.gov (United States)

    Jin, So Dam; Um, Sang Cheol; Lee, Jong Kook

    2015-08-01

    Surface modification with a biphasic composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) was performed on a zirconia substrate using a sol-gel method. An initial calcium phosphate sol was prepared by mixing a solution of Ca(NO3)2 · 4H20 and (C2H5O)3P(O), while both porous and dense zirconia were used as substrates. The sol-gel coating was performed using a spin coater. The coated porous zirconia substrate was re-sintered at 1350 °C 2 h, while coated dense zirconia substrate was heat-treated at 750 °C 1 h. The microstructure of the resultant HA/TCP coatings was found to be dependent on the type of zirconia substrate used. With porous zirconia as a starting substrate, numerous isolated calcium phosphate particles (TCP and HA) were uniformly dispersed on the surface, and the particle size and covered area were dependent on the viscosity of the calcium phosphate sol. Conversely, when dense zirconia was used as a starting substrate, a thick film of nano-sized HA particles was obtained after heat treatment, however, substantial agglomeration and cracking was also observed.

  19. Silica doped with lanthanum sol-gel thin films for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

    2012-06-01

    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: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  20. New Hybrid Materials Synthesized with Different Dyes by Sol-Gel Method

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    Ramona Gheonea

    2017-01-01

    Full Text Available One well-known method for hybrids synthesis with incorporated organic dyes is sol-gel method, which is based on the concept of molecular manipulation to design ceramics, glasses, and composites. The low-temperature process allows for the incorporation of guest organic molecules within the inorganic matrix, as well as for the synthesis of hybrid networks in which the organic and inorganic phases are interpenetrating. The aim of the work presented in this paper was the preparation of the gels with three different dyes, at different molar ratios by using the hydrolytic sol-gel process. The interaction of the dye and the oxide was examined by UV-vis spectroscopy and FT-IR. The thermal stability of the hybrid organic-inorganic xerogel formed here was studied by thermal analysis. The micrographs obtained by scanning electron microscopy (SEM revealed the high density of the films. Such characteristics indicate the possible application of these films in solar cells.

  1. Preparation of the SnO2 gate pH-ISFET by sol gel technology

    Science.gov (United States)

    Chou, Jung Chuan; Wang, Yii Fang

    2001-10-01

    In this paper, the sol-gel prepared SnO2 thin film is first applied for the pH sensing. We use the SnCl2(DOT)2H2O as the precursor. It is cheaper than other methods. The resulting solution is dropped on the gate of the SiO2 gate pH-ISFET (ion sensitive field effect transistor). After baking, the thin film will convert to SnO2. We also use the thermal evaporation system to prepare the SnO2 gate MOSFET. Then, we use the Keithley 236 instrument to measure the IDS-VG curves of the SnO2 gate MOSFET and pH-ISFET for the different pH buffer solutions. Since the MOSFET and pH-ISFET are fabricated on the same silicon wafer, the properties of these devices are identical. Therefore, we can use the experimental results and theoretical model of the pH-ISFET to find the pH sensitivity and pHPZC (pH at the point of zero charge) of the sol-gel prepared SnO2 gate pH-ISFET, which are about 57.36 mV/pH and 11.3, respectively.

  2. Preparation of single phase {beta}-spodumene powders by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Shawbing; Yang, Sheng [National Cheng-Kung University, Tainan (Taiwan). Dept. of Resources Engineering; Chen, Jenmin; Wu, Nangchung [National Cheng-Kung University, Tainan (Taiwan). Dept. of Material Science and Engineering; Wang, Moochin [National Kaohsiung Institute of Technology, Kaohsiung (Taiwan). Dept. of Mechanical Engineering

    1999-12-01

    The {beta}-spodumene (Li{sub 2}O{center_dot}Al{sub 2}O{sub 3}{center_dot}4SiO{sub 2}, LAS) powders were prepared by the sol-gel process using a mixture of silica sol, alumina sol and lithium nitrate solution. Si(OC{sub 2}H{sub 5}){sub 4}, Al(OC{sub 4}H{sub 9}{sup 8ec}){sub 3} and LiNO{sub 3} were used as the starting compounds. Thermogravimetric and differential thermal analyses (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), wavelength-dispersive spectroscopy (WDS), transmission electron microscopy (TEM) and electron diffraction (ED) analysis were utilized to characterize the {beta}-spodumene powders prepared by the sol-gel process. The crystallization temperature of the LAS gel powder estimated by TG/DTA was about 630 degree C. When the LAS dried gel was heated from 600 to 850 degree C, the crystallized powders of the single phase {beta}-spodumene were obtained. (author)

  3. Characterization and Modification of Mesoporous Silica Nanoparticles Prepared by Sol-Gel

    Directory of Open Access Journals (Sweden)

    Meysam Keshavarz

    2013-01-01

    Full Text Available Mesoporous silica nanoparticles (MSNs were synthesized by sol-gel reaction at normal pressure by using TEOS as a silica source and CTAB as a directing agent in ammonia solution at 323 K subsequently calcined at 823 K. Then inorganic pores were modified with metal-supported MSN with attention to the acidity, surface area, pore size, and ability of ion exchange. Crystalline size was shown to decrease up to 20 molar ratios of Si/Al followed by increasing while further adding nanoparticles-aluminium. Moreover, the XRD patterns revealed the mesostructured material for all with 2D hexagonal structure. The obtained results from the XRD patterns were confirmed by using BET and EDX. The BET surface areas revealed the spherical shape for all samples with a decrease in the pore volume and surface area for various AlMSNs which emphasized that the loading of Al and was compatible with XRD results. MSN was prepared by sol-gel methods followed by loading of Al in order to prepare AlMSN which possess strong Lewis acidic sites. This modification occurred by using various molar ratios of 0, 5, 10, 20, 50, and 100 Si/Al, respectively. The XRD patterns of various ratios of Si/Al were interpreted in terms of strain, nanocrystalline size, and distribution of the particle size by deriving Wiliamson Hall equation.

  4. 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.

  5. Soft nanoimprint lithography on SiO2 sol-gel to elaborate sensitive substrates for SERS detection

    Directory of Open Access Journals (Sweden)

    Frédéric Hamouda

    2017-12-01

    Full Text Available This paper presents a new alternative fabrication of biochemical sensor based on surface enhanced Raman scattering (SERS by soft nanoimprint lithography (S-NIL on SiO2 sol-gel. Stabilization of the sol-gel film is obtained by annealing which simplifies the manufacturing of these biosensors and is compatible with mass production at low cost. This detector relies on a specific pattern of gold nanodisks on a thin gold film to obtain a better sensitivity of molecules’ detection. Characterizations of SERS devices were performed on a confocal Raman microspectrophotometer after a chemical functionalization. We report a lateral collapse effect on poly(diméthylsiloxane (PDMS stamp for specific nanostructure dimensions. This unintentional effect is used to evaluate S-NIL resolution in SiO2 sol-gel.

  6. Sol-gel derived polymer composites for energy storage and conversion

    Science.gov (United States)

    Han, Kuo

    Sol-gel process is a simple chemistry to convert the small precursor molecules into an inorganic polymer, which could be applied to synthesize inorganic materials, modify the interface of materials, bridge the organic and inorganic materials, etc. In this dissertation, novel sol-gel derived composites have been developed for high dielectric breakdown capacitors, low high frequency loss capacitors and flexible piezoelectrics. Numerous efforts have been made in the past decades to improve the energy storage capability of composite materials by incorporating nanometer scale ceramic addictives with high dielectric permittivity into dielectric polymers with high breakdown strength. However, most composites suffer from the low breakdown strength and make the potential gain in energy density small. Here, a new chemical strategy is proposed that, through sol-gel reactions between ceramic precursors and functional groups at the end of the functionalized Poly(vinylidene fluoride -co-chlorotrifluoroethylene) chains, amorphous low permittivity ceramics was in-situ generated in the polymer matrix and cross-linked the polymer chains simultaneously. By carefully tuning precursors, the polymer/precursors feeding ratios, a series of nanocomposites were systematically designed. All the samples are comprehensively characterized and the structure-property correlations are well investigated. The optimal samples exhibit higher breakdown strength than the pristine polymer. The enhanced breakdown strength ascribed to low contrast in permittivity, great dispersion and improved electrical and mechanical properties. This newly developed approach has shown great promise for new composite capacitors. The percolative polymer composites have recently exhibited great potential in energy storage due to their high dielectric permittivities at the neighborhood of the percolation threshold. Yet high energy dissipation and poor voltage endurance of the percolative composites resulted from electrical

  7. Preparation and Characterization of Kynurenic Acid Occluded in Sol-Gel Silica and SBA-15 Silica as Release Reservoirs

    Directory of Open Access Journals (Sweden)

    Tessy López

    2014-01-01

    Full Text Available Kynurenic acid (KYNA may have important therapeutic effects in neurological disorders; however, its use as a neuroprotective agent is restricted due to its very limited ability to cross the blood brain barrier (BBB. For this reason, we are looking for new alternatives for KYNA to reach the brain; one of them is using drug delivery systems. To obtain KYNA release reservoirs, KYNA molecules were hosted in two different silica materials. The different KYNA-silica materials were characterized by means of several physical techniques. The spectroscopic studies showed that KYNA molecules remained unchanged once hosted in silica materials. The surface area values of KYNA-silica samples were substantially lower than those for pure silica materials due to the addition of the drug. The electronic micrographs showed that the sol-gel KYNA-silica material consisted of aggregates of nanoparticles around 50 nm in size. On the other hand, the typical SBA-15 hexagonal arrangement was observed, even when hosting KYNA molecules. KYNA release profiles, carried out during approximately 300 hours, showed a first stage of fast drug release followed by a slow release phase. The experimental values fitted to the Peppas equation indicate that the release mechanism was controlled by Fickian diffusion.

  8. PREPARATION OF NANO-SCALE a-Al2O3 POWDER BY THE SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Fatemeh Mirjalili

    2011-12-01

    Full Text Available Sol-gel method was applied to synthesize ultrafine nano a-alumina particles using aqueous solutions of aluminum isopropoxide and 0.5 M aluminum nitrate hydrate. Sodium dodecylbenzen suffocate and Sodium bis-2ethylhexyl sulfosuccinate were also used as surfactant stabilizing agents. The prepared solution was stirred for 48 hours at 60°C, then, the resultant gelled mass was dried at 90°C, and finally, calcined at 1200°C for about 1 hour. The samples were characterized by different techniques such as, Brunauer-Emmet-Teller method, X-ray diffraction, Thermogravimetry analysis, Differential Scanning Calorimetry, Fourier transform infrared spectra, Scanning electron microscopy and Transmission electron microscopy. The results indicated that the addition of sodium dodecylbenzen sufonates and sodium bis-2ethylhexyl sulfosuccinate not only affected the particle size and shape of the produced nanoparticles but also the degree of aggregation. However, sodium dodecylbenzen sufonate produced better dispersion and finer particles, in range of 20-30 nm, compared to Sodium bis- 2ethylhexyl sulfosuccinate.

  9. Investigation of sol-gel processed CuO/SiO2 nanocomposite as a potential photoanode material

    Directory of Open Access Journals (Sweden)

    Tenkyong Tenzin

    2015-12-01

    Full Text Available Synthesis and characterization of a highly efficient photoconductive nanocomposite comprising of two common metal oxides: copper oxide (CuO and silicon dioxide (SiO2 are being reported in this paper. The CuO/SiO2 nanocomposite has been synthesized using a cost-effective and facile sol gel route. The structural, chemical and optical properties of the prepared samples have been studied using various characterization techniques. The UV-Vis analysis revealed better absorption in the case of the nanocomposite as compared to its parent materials. X-ray diffraction (XRD analysis has been employed to determine the structural formation of the nanocomposite and the crystallite size with the use of Scherrer’s formula. The photo conductivity study of the sample showed enhanced photocurrent in the case of nanocomposite as compared to its single components, thus, presenting it as a potential candidate for solar cell applications, especially as photoanode material in the dye-sensitized solar cells (DSSC.

  10. Gadolinium-doped zinc oxide thin films prepared on different substrates by sol-gel spin-coating

    Science.gov (United States)

    Fadzilah, A. R. Nurul; Othman, R. N.; Miskon, A.; Sahdan, M. Z.; Tawil, S. N. M.

    2017-12-01

    Gadolinium (Gd) doped zinc oxide (ZnO) thin films were prepared by sol-gel spin-coating technique. The solution was prepared using zinc acetate dihydrate and monoethanolamine (MEA) as a stabilizer. The Gd-doped ZnO thin films were deposited on different substrates; glass, aluminium doped ZnO (AZO), fluorine doped tin oxide (FTO) and silicon (Si). The structural and optical properties of Gd-doped ZnO on different substrates were studied using X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscope-Energy Dispersive X-ray (FESEM-EDX) and Ultra Violet-Visible spectrophotometer (UV-Vis), respectively. Based on the XRD data, the crystallite size of the films was found to be in the range of 12.26 ˜ 22.95 nm, which shows a hexagonal wurtzite structure. Transmittance spectra of films deposited on AZO indicates a clear sinusoidal behavior as compared to samples prepared on glass and FTO. All samples exhibit magnetic properties at room temperature measured by means of Vibrating Sample Magnetometer (VSM).

  11. Fabrication and characterization of Gd2O2SO4:Tb3+ phosphors by sol-gel method

    Science.gov (United States)

    Aritman, I.; Yildirim, S.; Kisa, A.; Guleryuz, L. F.; Yurddaskal, M.; Dikici, T.; Celik, E.

    2017-02-01

    The objective of the innovative approaches of the scintillation materials to be used in the digital portal imaging systems in the radiotherapy applications is to research the GOS material production that has been activated with the rare earth elements (RE), to produce the scintillation detectors that have a rapid imaging process with a lesser radiation and higher image quality from these materials and to apply the radiographic imaging systems. The GOS: Tb3+ showed high emission peak and high x-ray absorption properties which have been determined for application to mammography and dental radiography. In this study, Gd2O2SO4:Tb3+ phosphors were fabricated by the sol-gel method that is a unique technique and not previously applied. Besides, the structural characterization of GOS: Tb3+ has been investigated. The strongest emission peak located at 549 nm under 312 nm UV light excitation was appeared on the GOS: Tb3+ phosphor particles. The characterization processing optimized by using FTIR, DTA-TG, XRD, XPS, SEM and the luminescence spectroscopy.

  12. Structure and optical properties of nanocrystalline NiO thin film synthesized by sol-gel spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, A.A. [King Abdulaziz University, Faculty of Science, Physics Department, Jeddah (Saudi Arabia); Mahmoud, Waleed E., E-mail: w_e_mahmoud@yahoo.co [King Abdulaziz University, Faculty of Science, Physics Department, Jeddah (Saudi Arabia); Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Yaghmour, S.J.; Al-Marzouki, F.M. [King Abdulaziz University, Faculty of Science, Physics Department, Jeddah (Saudi Arabia)

    2009-11-03

    NiO thin film was prepared by sol-gel spin-coating method. This thin film annealed at T = 600 deg. C. The structure of NiO thin film was investigated by means of X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). The optical properties of the deposited film were characterized from the analysis of the experimentally recorded transmittance and reflectance data in the spectral wavelength range of 300-800 nm. The values of some important parameters of the studied films are determined, such as refractive index (n), extinction coefficient (k), optical absorption coefficient (alpha) and band energy gap (E{sub g}). According to the analysis of dispersion curves, it has been found that the dispersion data obeyed the single oscillator of the Wemple-DiDomenico model, from which the dispersion parameters and high-frequency dielectric constant were determined. In such work, from the transmission spectra, the dielectric constant (epsilon{sub i}nfinity), the third-order optical nonlinear susceptibility chi{sup (3)}, volume energy loss function (VELF) and surface energy loss function (SELF) were determined.

  13. MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

    Directory of Open Access Journals (Sweden)

    Seyed Mohsen Latifi

    2015-03-01

    Full Text Available Ca ion release from bioactive biomaterials could play an important role in their bioactivity and osteoconductivity properties. In order to improve hydroxyapatite (HA dissolution rate, in situ apatite-silica nanocomposite powders with various silica contents were synthesized via sol-gel method and mechanisms controlling the Ca ion release from them were investigated. Obtained powders were characterized by X-ray diffraction (XRD and transmission electron spectroscopy (TEM techniques, acid dissolution test, and spectroscopy by atomic absorption spectrometer (AAS. Results indicated the possible incorporation of (SiO44- into the HA structure and tendency of amorphous silica to cover the surface of HA particles. However, 20 wt. % silica was the lowest amount that fully covered HA particles. All of the nanocomposite powders showed more Ca ion release compared with pure HA, and HA - 10 wt. % silica had the highest Ca ion release. The crystallinity, the crystallite size, and the content of HA, along with the integrity, thickness, and ion diffusion possibility through the amorphous silica layer on the surface of HA, were factors that varied due to changes in the silica content and were affected the Ca ion release from nanocomposite powders.

  14. Preparation and characterization of multilayer mesoporous γ-alumina membrane obtained via sol-gel using new precursors

    Directory of Open Access Journals (Sweden)

    Tafrishi R.

    2015-12-01

    Full Text Available In this paper, a mesoporous γ-alumina membrane coated on a macroporous α-alumina support via sol-gel method has been reported. A crack-free γ-alumina membrane was obtained by adding PVA to the alumina solution and optimum parameters of roughness, temperature and porosity were achieved. The support was dip-coated in different solutions using two new different solvents with different particle size distributions. Using these two solvents led to the uniform distribution of pore size in the final membrane. The alumina sols showed particle size distributions in the range of 20 to 55 nm which was measured by a DLS Zeta Sizer. X-ray diffraction technique, atomic force microscopy and scanning electron microscopy were used to characterize the membrane layer. XRD and DTA data for the γ-alumina membrane showed its thermal stability up to around 600 °C. The thickness of the mesoporous γ-alumina membrane was about 4 μm with 16 nm of surface roughness and 5 nm pore size. The resultant crack-free mesoporous membrane shows that the membrane preparation procedure was optimum. In this work, it has been investigated the performance of γ-alumina membranes for single gas permeation and separation of binary gas mixtures.

  15. Electrochemical and Oxidation Behavior of Yttria Stabilized Zirconia Coating on Zircaloy-4 Synthesized via Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    S. Rezaee

    2013-01-01

    Full Text Available Sol-gel 8 wt.% Yttria Stabilized Zirconia (YSZ thin films were prepared on zirconium (zircaloy-4 alloy by dip-coating technique followed by heat treating at various temperatures (200°C, 400°C, and 700°C in order to improve both electrochemical corrosion and high temperature oxidation properties of the substrate. Differential thermal analysis and thermogravimetric analysis (DTA-TG revealed the coating formation process. X-ray diffraction (XRD was used to determine the crystalline phase structure transformation. The morphological characterization of the coatings was carried out using scanning electron microscopy (SEM. The electrochemical behavior of the coated and uncoated samples was investigated by means of open circuit potential, Tafel, and electrochemical impedance spectroscopy (EIS in a 3.5 wt.% NaCl solution. The homogeneity and surface appearance of coatings produced was affected by the heat treatment temperature. According to the corrosion parameters, the YSZ coatings showed a considerable increase in the corrosion resistance, especially at higher heat treatment temperatures. The coating with the best quality, from the surface and corrosion point of view, was subjected to oxidation test in air at 800°C. The coated sample presented a 25% reduction in oxidation rate in comparison with bare substrate.

  16. In-vitro bioactivity, biocompatibility and dissolution studies of diopside prepared from biowaste by using sol-gel combustion method.

    Science.gov (United States)

    Choudhary, Rajan; Vecstaudza, Jana; Krishnamurithy, G; Raghavendran, Hanumantha Rao Balaji; Murali, Malliga Raman; Kamarul, Tunku; Swamiappan, Sasikumar; Locs, Janis

    2016-11-01

    Diopside was synthesized from biowaste (Eggshell) by sol-gel combustion method at low calcination temperature and the influence of two different fuels (urea, l-alanine) on the phase formation temperature, physical and biological properties of the resultant diopside was studied. The synthesized materials were characterized by heating microscopy, FTIR, XRD, BET, SEM and EDAX techniques. BET analysis reveals particles were of submicron size with porosity in the nanometer range. Bone-like apatite deposition ability of diopside scaffolds was examined under static and circulation mode of SBF (Simulated Body Fluid). It was noticed that diopside has the capability to deposit HAP (hydroxyapatite) within the early stages of immersion. ICP-OES analysis indicates release of Ca, Mg, Si ions and removal of P ions from the SBF, but in different quantities from diopside scaffolds. Cytocompatability studies on human bone marrow stromal cells (hBMSCs) revealed good cellular attachment on the surface of diopside scaffolds and formation of extracellular matrix (ECM). This study suggests that the usage of eggshell biowaste as calcium source provides an effective substitute for synthetic starting materials to fabricate bioproducts for biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Preparation of surface-modified ZnO quantum dots through an ultrasound assisted sol-gel process

    Science.gov (United States)

    Moghaddam, E.; Youzbashi, AA; Kazemzadeh, A.; Eshraghi, MJ

    2015-08-01

    A synthetic process of zinc oxide quantum dots (QDs) is presented. It is based on a sol-gel process, carried out in an ultrasonic bath. It allows the formation of the stable colloids, containing surface-modified ZnO QDs with the aid of 3-aminopropyltriethoxysilane (APTES) as a capping agent. For this purpose, alcoholic solutions of zinc acetate dihydrate and potassium hydroxide were used as the reactants. Effect of KOH concentration, ultrasonic irradiation, and also the presence of capping agent on the characteristics of the final product were investigated. The synthesized samples were characterized by various analytical techniques such as XRD, TEM, FT-IR, UV-vis and PL spectroscopy. XRD analysis revealed the direct formation of hexagonal wurtzite nanocrystals with average size of ∼3 nm confirmed by TEM and UV-vis spectroscopy. The PL spectroscopy indicated the influence of the capping agent on reducing the defects formation during the growth of the QDs. The present synthesis method was found to be a cost-effective and simple solution route for producing pure semiconductor ZnO QDs, exhibiting the quantum confinement effects, suitable for optical and optoelectronic applications.

  18. Sol-gel synthesis, solid sintering, and thermal stability of single-phase YCoO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Guanlin; Shen, Hongzhi; Li, Liang; Zhou, Jing; Yang, Hang [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Xue, Yanfeng [College of Physics, Jilin University, Changchun 130012 (China); Feng, Shuo [School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Xu, Dapeng [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); College of Physics, Jilin University, Changchun 130012 (China)

    2012-07-15

    Using Y(NO{sub 3}){sub 3}.6H{sub 2}O and Co(NO{sub 3}){sub 2}.6H{sub 2}O as the starting materials, the single-phase YCoO{sub 3} has been synthesized by a two-step process involving a sol-gel technique and a sintering method. The structure, electromagnetic properties, and thermal stability of the synthesized samples were measured by XRD, thermogravimetry and differential thermal analysis (TG-DTA), TEM, and vibration sample magnetometer (VSM). The experimental results show that the synthesis conditions of the single-phase YCoO{sub 3} are 900-950 C for 10 h in air. And the synthesis temperature is extended to 900-1000 C and the sintering time is shortened to 5 h in an oxygen atmosphere. The synthesized powders have orthorhombic structure, with a diameter of {proportional_to}30 nm, which is stable in air below 1050 C and in oxygen atmosphere below 1100 C. Above those temperatures, YCoO{sub 3} decomposes into Y{sub 2}O{sub 3} and Co{sub 3}O{sub 4}. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 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.)

  20. Synthesis, characterization and photocatalytic applications of Zn-doped TiO2 nanoparticles by sol-gel method

    Science.gov (United States)

    Aware, Dinkar V.; Jadhav, Shridhar S.

    2016-10-01

    Mesoporous, nanocrystalline, Zinc-doped TiO2 nanoparticles were synthesized by surfactant-assisted sol-gel method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-VIS spectrometer techniques were used to characterize the synthesized products. XRD results confirm the formation of the anatase phase for the TiO2 nanoparticles, with crystallite sizes in the range of 12.6-18.1 nm. The small crystallite size and doping with Zinc ion inhibit phase transformation and promote the growth of the TiO2 anatase phase. The SEM and TEM micrographs revealed the spherical-like morphology with average diameter of about 12-18 nm which is in agreement with XRD results. The optical study shows that doping ions lead to an increase in the absorption edge wavelength and a decrease in the band gap energy of titania. Photocatalytic activity of the synthesized nanomaterials was successfully tested for photodegradation of methyl red as model pollutant under UV light. The photocatalytic activity results confirm that the doped nanoparticles show higher activity than undoped titania. The small grain size, high crystallinity, high specific surface area and decrease in the band gap energy of doped titania may be responsible for the high photocatalytic activity.

  1. Modified thermoresponsive Poloxamer 407 and chitosan sol-gels as potential sustained-release vaccine delivery systems.

    Science.gov (United States)

    Kojarunchitt, Thunjiradasiree; Baldursdottir, Stefania; Dong, Yao-Da; Boyd, Ben J; Rades, Thomas; Hook, Sarah

    2015-01-01

    Thermoresponsive, particle-loaded, Poloxamer 407 (P407)-Pluronic-R® (25R4) or chitosan-methyl cellulose (MC) formulations were developed as single-dose, sustained release vaccines. The sol-gels, loaded either with a particulate vaccine (cubosomes) or soluble antigen (ovalbumin) and adjuvants (Quil A and monophosphoryl lipid A), were free-flowing liquids at room temperature and formed stable gels at physiological temperatures. Rheological results showed that both systems meet the criteria of being thermoresponsive gels. The P407-25R4 sol-gels did not significantly sustain the release of antigen in vivo while the chitosan-MC sol-gels sustained the release of antigen up to at least 14 days after administration. The chitosan-MC sol-gels stimulated both cellular and humoral responses. The inclusion of cubosomes in the sol-gels did not provide a definitive beneficial effect. Further analysis of the formulations with small-angle X-ray scattering (SAXS) revealed that while cubosomes were stable in chitosan-MC gels they were not stable in P407-25R4 formulations. The reason for the mixed response to cubosome-loaded vehicles requires more investigation, however it appears that the cubosomes did not facilitate synchronous vaccine release and may in fact retard release, reducing efficacy in some cases. From these results, chitosan-MC sol-gels show potential as sustained release vaccine delivery systems, as compared to the P407-25R4 system that had a limited ability to sustain antigen release. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. A sol-gel derived pH-responsive bovine serum albumin molecularly imprinted poly(ionic liquids) on the surface of multiwall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Mingming, E-mail: liumm@mail.hzau.edu.cn [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Pi, Jiangyan; Wang, Xiaojie; Huang, Rong; Du, Yamei; Yu, Xiaoyang; Tan, Wenfeng; Liu, Fan [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Shea, Kenneth J., E-mail: kjshea@uci.edu [Department of Chemistry, University of California-Irvine, Irvine, CA 92697 (United States)

    2016-08-17

    A pH-responsive surface molecularly imprinted poly(ionic liquids) (MIPILs) was prepared on the surface of multiwall carbon nanotubes (MWCNTs) by a sol-gel technique. The material was synthesized using a 3-aminopropyl triethoxysilane modified multiwall carbon nanotube (MWCNT-APTES) as the substrate, bovine serum albumin (BSA) as the template molecule, an alkoxy-functionalized IL 1-(3-trimethoxysilyl propyl)-3-methyl imidazolium chloride ([TMSPMIM]Cl) as both the functional monomer and the sol-gel catalyst, and tetraethoxysilane (TEOS) as the crosslinking agent. The molecular interaction between BSA and [TMSPMIM]Cl was quantitatively evaluated by UV–vis spectroscopy prior to polymerization so as to identify an optimal template/monomer ratio and the most suitable pH value for the preparation of the MWCNTs@BSA-MIPILs. This strategy was found to be effective to overcome the problems of trial-and-error protocol in molecular imprinting. The optimum synthesis conditions were as follows: template/monomer ratio 7:20, crosslinking agent content 2.0–2.5 mL, temperature 4 °C and pH 8.9 Tris–HCl buffer. The influence of incubation pH on adsorption was also studied. The result showed that the imprinting effect and selectivity improved significantly with increasing incubation pH from 7.7 to 9.9. This is mainly because the non-specific binding from electrostatic and hydrogen bonding interactions decreased greatly with the increase of pH value, which made the specific binding affinity from shape selectivity strengthened instead. The polymers synthesized under the optimal conditions were then characterized by BET surface area measurement, FTIR, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The adsorption capacity, imprinting effect, selective recognition and reusability were also evaluated. The as-prepared MWCNTs@BSA-MIPILs were also found to have a number of advantages including high surface area (134.2 m{sup 2} g{sup −1}), high adsorption

  3. Improvement of UV Protection Properties of the Textile from Natural Fibres by the Sol-Gel Method

    OpenAIRE

    Vihodceva, S; Kukle, S

    2013-01-01

    In this research pure cotton textile has been modified by the sol-gel technology to implement zinc oxide nanolevel coating on textile surface to ensure ultraviolet (UV) radiation protection. One of the advantages of this method is the possibility to obtain thin layers on various materials, as well as the sol-gel layers can cover all fibres with enough high adhesion. Comparison of coatings of samples prepared using different concentrations of TEOS in nano-sols and thermal post-treatment of sam...

  4. Sol-gel synthesis of quaternary (P2O5)55-(CaO)25-(Na2O)(20-x)-(TiO2) x bioresorbable glasses for bone tissue engineering applications (x = 0, 5, 10, or 15).

    Science.gov (United States)

    Foroutan, Farzad; Walters, Nick J; Owens, Gareth J; Mordan, Nicola J; Kim, Hae-Won; de Leeuw, Nora H; Knowles, Jonathan C

    2015-08-26

    In the present study, we report a new and facile sol-gel synthesis of phosphate-based glasses with the general formula of (P2O5)55-(CaO)25-(Na2O)(20-x)-(TiO2) x , where x = 0, 5, 10 or 15, for bone tissue engineering applications. The sol-gel synthesis method allows greater control over glass morphology at relatively low processing temperature (200 °C) in comparison with phosphate-based melt-derived glasses (~1000 °C). The glasses were analyzed using several characterization techniques, including x-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance ((31)P MAS-NMR), Fourier transform infrared (FTIR) spectroscopy and energy-dispersive x-ray (EDX) spectroscopy, which confirmed the amorphous and glassy nature of the prepared samples. Degradation was assessed by measuring the ion release and pH change of the storage medium. Cytocompatibility was also confirmed by culturing osteoblast-like osteosarcoma cell line MG-63 on the glass microparticles over a seven-day period. Cell attachment to the particles was imaged using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results revealed the potential of phosphate-based sol-gel derived glasses containing 5 or 10 mol% TiO2, with high surface area, ideal dissolution rate for cell attachment and easily metabolized dissolution products, for bone tissue engineering applications.

  5. Evolution of microstructure in mixed niobia-hybrid silica thin films from sol-gel precursors.

    Science.gov (United States)

    Besselink, Rogier; Stawski, Tomasz M; Castricum, Hessel L; ten Elshof, Johan E

    2013-08-15

    The evolution of structure in sol-gel derived mixed bridged silsesquioxane-niobium alkoxide sols and drying thin films was monitored in situ by small-angle X-ray scattering. Since sol-gel condensation of metal alkoxides proceeds much faster than that of silicon alkoxides, the incorporation of d-block metal dopants into silica typically leads to formation of densely packed nano-sized metal oxide clusters that we refer as metal oxide building blocks in a silica-based matrix. SAXS was used to study the process of niobia building block formation while drying the sol as a thin film at 40-80°C. The SAXS curves of mixed niobia-hybrid silica sols were dominated by the electron density contrast between sol particles and surrounding solvent. As the solvent evaporated and the sol particles approached each other, a correlation peak emerged. Since TEM microscopy revealed the absence of mesopores, the correlation peak was caused by a heterogeneous system of electron-rich regions and electron poor regions. The regions were assigned to small clusters that are rich in niobium and which are dispersed in a matrix that mainly consisted of hybrid silica. The correlation peak was associated with the typical distances between the electron dense clusters and corresponded with distances in real space of 1-3 nm. A relationship between the prehydrolysis time of the silica precursor and the size of the niobia building blocks was observed. When 1,2-bis(triethoxysilyl)ethane was first hydrolyzed for 30 min before adding niobium penta-ethoxide, the niobia building blocks reached a radius of 0.4 nm. Simultaneous hydrolysis of the two precursors resulted in somewhat larger average building block radii of 0.5-0.6 nm. This study shows that acid-catalyzed sol-gel polymerization of mixed hybrid silica niobium alkoxides can be rationalized and optimized by monitoring the structural evolution using time-resolved SAXS. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Reactive Molecular Dynamics Investigations of Alkoxysilane Sol-Gel and Surface Coating Processes

    Science.gov (United States)

    Deetz, Joshua David

    The ability to generate nanostructured materials with tailored morphology or chemistry is of great technological interest. One proven method of generating metal-oxide materials, and chemically modifying metal-oxide surfaces is through the reactions of molecular building blocks known as alkoxysilanes. Alkoxysilanes are a class of chemicals which contain one or more organic alkoxy groups bonded to silicon atoms. Alkoxysilane (Si-O-R) chemical groups can undergo reactions to form bridges (Si-O-M) with metal oxides. Due to their ability to "attach" to metal-oxides through condensation reactions, alkoxysilanes have a number of interesting applications, such as: the generation of synthetic siloxane materials through the sol-gel process, and the formation of functionalized surface coatings on metal-oxide surfaces. Despite widespread study of sol-gel and surface coatings processes, it is difficult to predict the morphology of the final products due to the large number of process variables involved, such as precursor molecule structure, solvent effects, solution composition, temperature, and pH. To determine the influence of these variables on the products of sol-gel and coatings processes reactive molecular dynamics simulations are used. A reactive force field was used (ReaxFF) to allow the chemical bonds in simulation to dynamically form and break. The force field parameters were optimized using a parallel optimization scheme with a combination of experimental information, and density functional theory calculations. Polycondensation of alkoxysilanes in mixtures of alcohol and water were studied. Steric effects were observed to influence the rates of hydrolysis and condensation in solutions containing different precursor monomers. By restricting the access of nucleophiles to the central silicon atom, the nucleation rate of siloxanes can be controlled. The influence of solution precursor, water, and methanol composition on reaction rates was explored. It was determined that

  7. Encapsulation of fluorescence vegetable extracts within a templated sol-gel matrix

    Science.gov (United States)

    Lacatusu, Ioana; Badea, Nicoleta; Nita, Rodica; Murariu, Alina; Miculescu, Florin; Iosub, Ion; Meghea, Aurelia

    2010-04-01

    The sol-gel encapsulation of labile substances with specific properties and recognition functions within robust polymer matrices remains a challenging task, despite the considerable research that has been focused on this field. Numerous studies have been reported in the field of sol-gel processes regarding different physical and chemical packing of sensitive biomolecules encapsulated in silica matrix. In this paper the classical sol-gel synthesis has been used under mild conditions in order to minimize denaturizing effects on encapsulated active vegetable extracts from flavones class. The silica templated matrix was obtained by using two types of surfactants with different alkyl chain (didodecyldimethyl-ammonium bromide and trioctadecylmetilammonium bromide) as structure-directing agents for the silicon oxide framework. An organic precursor of silicic acid (triethoxymethylsilane) has been used and it was processed by competitive hydrolysis and polycondensation reactions under controlled directions assured by the presence of oriented template. Silica materials thus obtained are used for encapsulation of two flavonoid samples containing as active principles two sources: rutin and a vegetable extract from Begonia plant. The synthesis of encapsulated nanocompounds has been achieved taking into consideration the specific interaction between the colloidal gel precursors and molecular structures of selected biomolecules. The main objective was to improve the encapsulation conditions for specific biomolecules, searching for the highest stability and functionality without loosing the quality of the flavonoid properties, particularly optical properties like fluorescence. The structural properties of the encapsulated samples have been studied by FT-IR and UV-VIS spectroscopy, thermal analysis and SEM/EDX analysis. The fluorescence experiments showed that, in the case of all four encapsulated samples, the fluorescence spectra manifest a significant increase in intensity

  8. Co{sub 3}O{sub 4}/TiO{sub 2} films obtained by laser ablation and sol-gel for the reaction of oxygen liberation in alkaline medium; Peliculas de Co{sub 3}O{sub 4}/TiO{sub 2} obtenidas por ablacion laser y sol-gel para la reaccion de desprendimiento de oxigeno en medio alcalino

    Energy Technology Data Exchange (ETDEWEB)

    Perez A, J.; Fernandez V, S. M.; Escobar A, L.; Jimenez B, J. [Departamento de Quimica, ININ, Carretera Mexico-Toluca s/n, Ocoyoacac, Estado de Mexico (Mexico)

    2008-07-01

    The laser ablation technique known as Pulsed Laser Deposition (PLD) is used for obtaining thin films of TiO{sub 2}/SnO{sub 2}, which was later modified with Co{sub 3}O{sub 4} by PLD or by sol-gel technique. The films were characterized by X-ray diffraction, ultraviolet Vis and Raman spectroscopies, scanning electron microscopy and energy analysis of the dispersed X-rays produced by Auger decay. The anatase phase with particles of nano metric size was obtained by depositing the titanium dioxide in argon atmosphere. The Co{sub 3}O{sub 4} films obtained by PLD on the TiO{sub 2} showed the same morphology. The electrocatalytic activity of the films that were used as photo anodes for the reaction of oxygen liberation was carried out in the darkness, with environment light and the light emitted by a xenon lamp. The current density was higher for films of Co{sub 3}O{sub 4}/TiO{sub 2}/SnO{sub 2} obtained by PLD that for cobalt dioxide of mixed valence obtained by sol-gel. (Author)

  9. Analysis of milk ageing by a sol-gel sensors array

    Science.gov (United States)

    Siciliano, P.; Rella, R.; Capone, S.; Taurino, A.; Vasanelli, L.

    2000-12-01

    There is growing interest in the development of electronic odours-detection multisensor systems for objective evaluation of aroma food. Study of food storage, freshness control and ageing is one of the most important application field for this new class of device (named "electronic nose"). In this paper we report a specific application of a semiconductor thin films based electronic nose in the control of the rancidity of two different milk (UHT and pasteurised) during their storage days. The active elements of the array were undoped and Os-, Ni-, Pt-, Pd-doped SnO2 thin films prepared by the sol-gel method. Principal Component Analysis (PCA), applied to the data coming from the response of the sensors, gave satisfactory results in tracking dynamic evolution of milk, that could lead to commercial application in the food industry.

  10. Sol-Gel Synthesis and Characterization of Selected Transition Metal Nano-Ferrites

    Directory of Open Access Journals (Sweden)

    Aurelija GATELYTĖ

    2011-09-01

    Full Text Available In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12, yttrium perovskite ferrite (YFeO3, cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively powders by an aqueous sol-gel processes are investigated. The metal ions, generated by dissolving starting materials of transition metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the transition metal ferrite ceramics. The phase purity of synthesized nano-compounds was characterized by infrared spectroscopy (IR and powder X-ray diffraction analysis (XRD. The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM.http://dx.doi.org/10.5755/j01.ms.17.3.598

  11. Coating of LaCoO3 thin film with sol-gel dip coating method.

    Science.gov (United States)

    Okuyucu, Hasan; Dahl, Paul Inge; Einarsrud, Mari Ann

    2008-02-01

    LaCoO3 thin film was coated on Al2O3 single crystal by sol-gel route. Appropriate composition of precursors, chelating agents and the solvent put together into a flask and magnetically stirred on a magnetic stirrer. After having the red transparent solution, it was stirred for 12 hours before coating. Ultrasonically cleaned substrate is dipped into the solution and taken immediately into vertical furnace which is preheated at 550 degrees C. A dense amorphous film is coated on the substrate. Fired amorphous films are annealed at temperature between 900 degrees C and 1000 degrees C for 20 minutes in the air. Then coated film was characterized by means of XRD, AFM, and SEM. Conductivity of the film was measured to be -0.1819 for 881 degrees C for the log sigma value by assuming the thickness as

  12. 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)

  13. Synthesis and Characterization of Modified Cellulose Acetate Propionate Nanocomposites via Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Patrycja Wojciechowska

    2013-01-01

    Full Text Available In this study novel organic-inorganic hybrid nanocomposites were synthesized from modified cellulose acetate propionate (MCAP via sol-gel reaction at ambient temperature. The inorganic phase was introduced in situ by hydrolysis-condensation of tetraethoxysilane (TEOS in different concentrations, under acid catalysis, in the presence of organic polymer dissolved in acetone. The chemical modification of CAP was monitored by infrared spectroscopy (IR. The nanocomposites structure was characterized by IR analysis and solid state 29Si NMR studies. The spectral data revealed that organic and inorganic phases are linked through covalent bound. Surface morphology of the samples and the degree of dispersion of inorganic phase in the polymer matrix were investigated using atomic force microscopy (AFM and scanning electron microscopy (SEM. The actual incorporation of the inorganic component into the hybrid nanocomposites was deducted from the residual weight according to thermogravimetric analysis (TGA.

  14. Biochemical properties of Bacillus sp. ITP-001 lipase immobilized with a sol gel process

    Directory of Open Access Journals (Sweden)

    Nayara Bezerra Carvalho

    2013-01-01

    Full Text Available This work presents biochemical characterization of a lipase from a new strain of Bacillus sp. ITP-001, immobilized using a sol gel process (IB. The results from the biochemical characterization of IB showed increased activity for hydrolysis, with 526.63 U g-1 at pH 5.0 and 80 ºC, and thermal stability at 37 ºC. Enzymatic activity was stimulated by ions such as EDTA, Fe+3, Mn+2, Zn+2, and Ca+2, and in various organic solvents. Kinetic parameters obtained for the IB were Km = 14.62 mM, and Vmax = 0.102 mM min-1 g-1. The results of biochemical characterization revealed the improved catalytic properties of IB.

  15. Organofunctional Trialkoxysilane Sol-Gel Precursors for Chemical Modi! cation of Textile Fibres

    Directory of Open Access Journals (Sweden)

    Jelena Vasiljević

    2017-07-01

    Full Text Available This paper reviews the use of organofunctional trialkoxysilane sol-gel precursors as contemporary fi nishing agents for the chemical modification of textile fires. The structures of organofunctional trialkoxysilanes are presented and compared to those of other silicon-based organic-inorganic hybrid materials. We describe the steps in the application procedure and the polysilsesquioxane coating fabrication on the surface of textile fibres. The functionalities, e.g., water and oil repellency, flame retardancy, antimicrobial properties, electrical conductivity and anti-static properties, are discussed in relation to the chemical structures of the precursor organic moiety, mechanisms and principals of the coating activity and its washing fastness. The most important published scientific results on organofunctional trialkoxysilanes applications to the surface of textile fibres are discussed with an emphasis on the creation of a multicomponent coating with multifunctional protective properties.

  16. Effect of Polymers (PEG and PVP on Sol-Gel Synthesis of Microsized Zinc Oxide

    Directory of Open Access Journals (Sweden)

    Thilagavathi Thirugnanam

    2013-01-01

    Full Text Available Fibers irregular and seed-like microcrystalline ZnO were synthesized by using a cost-effective and low temperature aqueous sol-gel method. Various polymers, namely, polyethylene glycol 6000 (PEG 6000 and polyvinyl pyrrolidone (PVP, were used as structure directing agents. The samples were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and scanning electron microscopy (SEM. The X-ray diffraction pattern revealed the formation of phase-pure ZnO micropowders. It is observed that the polymers play an important role in modifying the surface morphology and the size of the crystallites. A compact granular morphology is observed for the ZnO samples without polymer. The samples exhibit microparticles of size 100 nm for PVP and for PEG-mediated growth, whereas microporous corrugated morphology is observed for added PEG-mediated micropowder. FTIR study is used to confirm the structural modifications occurring in the polymers.

  17. Seed-assisted sol-gel synthesis and characterization of nanoparticular V2O5/anatase

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Kristensen, Steffen Buus; Riisager, Anders

    2009-01-01

    Nanoparticular supported vanadia materials with crystalline anatase support with a narrow size distribution around 12 nm have been synthesized by a new facile sol-gel, co-precipitation method using decomposable ammonium chloride seed crystals. The materials have been characterized by means of X......-ray powder diffraction, transmission electron microscopy and nitrogen physisorption. The synthesized high-surface area anatase particles allowed a loading of up to 15 wt.% vanadia without exceeding monolayer coverage of V2O5 in contrast to typical analogous industrial catalysts which only can accommodate 3......-5 wt.% vanadia. These materials are promising candidates for improved catalysts for, e.g., oxidation reactions and selective catalytic reduction of NO (X) in flue gases....

  18. Synthesis and Characterization of ZnO Nanoparticles Using Sol-gel Process

    Directory of Open Access Journals (Sweden)

    Jayasree ALURI

    2016-05-01

    Full Text Available In the Present work structural, morphological and compositional properties of ZnO nanopowders synthesized using Zinc nitrate and NaOH using sol-gel process were reported. The synthesized nanopowders were further analyzed using X-Ray Diffraction (XRD, Scanning electron microscopy (SEM and Fourier Transform Infrared (FTIR spectroscopic characterizations. Crystalline size and Lattice strain determined from XRD spectra. Morphology of Nanopowders viewed from SEM images observed at different magnifications. The presence of Functional groups analyzed from FTIR spectra. From the results it was very clear that particles synthesized using Zinc nitrate and NaOH plays a vital role on crystalline size, surface morphology of Nanopowders. Synthesized nanopowders can be utilized as building materials in fabrication of various optoelectronic devices including solar cells, LED’s etc. due to its significant structural, morphological and optical properties.

  19. The enhancement of benzotriazole on epoxy functionalized silica sol-gel coating for copper protection

    Science.gov (United States)

    Peng, Shusen; Zhao, Wenjie; Li, He; Zeng, Zhixiang; Xue, Qunji; Wu, Xuedong

    2013-07-01

    The influence of the amount of benzotriazole (BTA) on the wetting and anticorrosion ability of the epoxy functionalized silica sol-gel (ESol) coating was studied by various complementary methods. IR results demonstrate that BTA reacted with ESol through a 1:1 addition reaction of Nsbnd H to epoxy group. The water contact angle of the ESol coating increases with an increase in the amount of BTA. SEM and adhesion tests reveal that BTA could improve the adhesion of ESol to copper surface. Moreover, the best protection was achieved when the amount of BTA equals to the molar number of epoxy group in the ESol coating according to the results of electrochemical measurements and salt spray test.

  20. Sol- Gel Synthesis of Hematite Nanoparticles and Photo Degradation of Cibacron Red FN-R Dye

    Directory of Open Access Journals (Sweden)

    Ahlam M. Farhan

    2017-09-01

    Full Text Available This paper describes the synthesis of α- Fe2O3 nanoparticles by sol-gel route using carboxylic acid(2-hydroxy benzoic acid as gelatin media and its photo activity for degradation of cibacron red dye . Hematite samples are synthesized at different temperatures: 400, 500, 600, 700, 800 and 900 ᴼC at 700 ᴼC the α-Fe2O3 nanoparticles are formed with particle size 71.93 nm. The nanoparticles are characterized by XRD , SEM, AFM and FTIR . The 0.046 g /l of the catalyst sample shows high photo activity at 3x10-5M dye concentration in acidic medium at pH 3.

  1. New Synthesis of Ferrite-Silica Nanocomposites by a Sol-Gel Auto-Combustion

    Science.gov (United States)

    Cannas, C.; Musinu, A.; Peddis, D.; Piccaluga, G.

    2004-06-01

    A sol-gel autocombustion method was used to synthesize nanometric metal-oxide powders, and was extended for the first time to prepare ferrite-silica nanocomposites. The gels obtained by mixing suitable amounts of citric acid, metal nitrates, ammonia (pure phases) and tetraethylortosilicate (nanocomposites) were converted directly to ferrite (either γ-Fe2O3 or CoFe2O4) or ferrite-silica composites through a rapid autocombustion reaction. The combustion involves a thermally induced autocatalytic oxidation-reduction reaction between the nitrate and the citrate ions. The sample characterization by X-ray diffraction, transmission electron microscopy and N2 physisorption measurements revealed nanosized pure phase powders and nanocomposites in which small spherical nanoparticles (mean size 3.5 and 5.0nm, respectively for the γ-Fe2O3and CoFe2O4) are homogeneously dispersed over a mesoporous silica matrix.

  2. Optical and Mechanical Characterization of Zirconium Based Sol-Gel Coatings on Glass

    Directory of Open Access Journals (Sweden)

    Sitarz M.

    2016-12-01

    Full Text Available The basic factor limiting the use of glasses is their unsatisfactory mechanical strength. The improvement of the mechanical strength of glasses is usually obtained by applying their respective thin surface layers. The object of the research was glass coated with zirconium oxide. For the application of zirconium oxide layer, dip-coating method was used. The resulting materials were subjected to detailed examination of the microstructure (SEM, and mechanical tests (Vickers hardness and modulus of elasticity. In order to evaluate the optical characteristics, the tests were performed by UV/VIS. The thickness of the overlying layers were determined using the method of ellipsometry. The study showed that the obtained sol-gel layer of zirconium oxide (IV on glasses influence the improvement of the mechanical properties. It has been shown that the applied layers have high adhesion to the substrate.

  3. A novel green nonaqueous sol-gel process for preparation of partially stabilized zirconia nanopowder

    Directory of Open Access Journals (Sweden)

    Guo Feng

    2017-09-01

    Full Text Available A novel green nonaqueous sol-gel process was developed to prepare 3 mol% Y2O3-doped ZrO2 nanopowder from zirconium oxychloride and without need for washing of the obtained particles. It was shown that highly dispersive nanometer-scale zirconia powder with the particle size of 15–25 nm and BET surface area of 41.2 m2/g can be prepared. The sintering behaviour was also investigated. Density of the translucent body sintered at 1400 °C is 98.7 ± 0.3% of its theoretical density and the surface and cross section areas are dense without holes or other defects. The bending strength of the sintered sample is 928 ± 64 MPa.

  4. Synthesis of indium tin oxide nanoparticles by a nonhydrolytic sol-gel method

    Directory of Open Access Journals (Sweden)

    Gabriel M. Silva

    2012-01-01

    Full Text Available Indium tin oxide nanoparticles were synthesized in two different sizes by a nonhydrolytic sol-gel method. These powders were then transformed into ITO via an intermediate metastable state at between 300 and 600 ºC. The presence of characteristic O-In-O and O-Sn-O bands at 480 and 670 cm-1 confirmed the formation of ITO. The X-ray diffraction patterns indicated the preferential formation of metastable hexagonal phase ITO (corundum type as opposed to cubic phase ITO when the reflux time was less than 3 h and the heat treatment temperature was below 600 ºC. Particle morphology and crystal size were examined by scanning electron microscopy.

  5. Structural and optical properties of KNN nanoparticles synthesized by a sol-gel combustion method

    Science.gov (United States)

    Khorrami, Gh. H.; Mousavi, M.; Dowran, M.

    2017-05-01

    In this paper, potassium sodium niobate (KNN) nanopowders were successfully obtained by sol-gel combustion method. According to thermogravimetric analysis (TGA) results, the produced xerogel was calcined at 500∘C, 600∘C, and 700∘C to obtain KNN powders. The structural and optical properties of the prepared powders were studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and UV-vis spectroscopy. The XRD patterns indicated formation of orthorhombic KNN samples. The Scherrer formula and size-strain plot (SSP) method were employed to calculate crystallite size and lattice strain of the KNN powders. The TEM image revealed that the average particle size of the prepared samples is about 30 nm and they have cubic shape. The optical band gap energy of the samples was calculated using UV-vis absorbance spectra of the samples along with Tauc relation.

  6. Cerium-activated sol-gel silica glasses for radiation dosimetry in harsh environment

    Science.gov (United States)

    El Hamzaoui, Hicham; Capoen, Bruno; Helou, Nissrine Al; Bouwmans, Géraud; Ouerdane, Youcef; Boukenter, Aziz; Girard, Sylvain; Marcandella, Claude; Duhamel, Olivier; Chadeyron, Geneviève; Mahiou, Rachid; Bouazaoui, Mohamed

    2016-04-01

    Cerium-doped silica glass has been prepared for ionizing radiation dosimetry applications, using the sol-gel route and densification under different atmospheres. In comparison with the glass densified under air atmosphere, the one obtained after sintering the xerogel under helium gas presents improved optical properties, with an enhancement of the photoluminescence quantum yield up to 33%, which is attributed to a higher Ce3+ ions concentration. Such a glassy rod has been jacketed in a quartz tube and then drawn at high temperature to a cane, which has been used as active material in a fibered remote x-ray radiation dosimeter. The sample exhibited a reversible linear radioluminescence intensity response versus the dose rate up to 30 Gy s-1. These results confirm the potentialities of this material for in vivo or high rate dose remote dosimetry measurements.

  7. TEM characterization of organic nanocrystals grown in sol-gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, Virginie; Bacia, Maria [CNRS and Universite Joseph Fourier, Institut Neel (France); Putaux, Jean-Luc [ICMG-CNRS, Centre de Recherches sur les Macromolecules Vegetales (France); Ibanez, Alain [CNRS and Universite Joseph Fourier, Institut Neel (France)], E-mail: alain.ibanez@grenoble.cnrs.fr

    2008-01-15

    The tetracene molecule (2,3-benzanthracene, C{sub 8}H{sub 12}) was used to synthesize nanocrystals grown in sol-gel thin films, ranging from 10 to 100 nm of diameter. This confined nucleation and growth was compared to microcrystallizations of the same molecule in free solution. Transmission electron microscopy (TEM) was used to characterize these two kinds of tetracene crystals. The observation was performed under low-dose illumination to avoid amorphization of the samples during electron irradiation. Spatial confinement and size distribution of micro- and nanocrystals were compared. Using electron microdiffraction and diffraction patterns simulations, we showed that free microcrystals and nanocrystals confined in gel glasses exhibit the same triclinic P-bar 1 structure. In addition, time-resolved spectroscopy was used to record fluorescence decays, showing a monoexponential fluorescence decay for nanocrystals while microcrystals exhibit a multiexponential decay. The simple signature of nanocrystals luminescence is promising for the future development of chemical or biological sensors.

  8. Ozonation and sol-gel method to obtain Cu/Cu O nanoparticles from cyanidation wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Soria A, M. J.; Puente S, D. M.; Carrillo P, F. R. [Universidad Autonoma de Coahuila, Facultad de Metalurgia, Carretera 57 Km 4.5, 25710 Monclova, Coahuila (Mexico); Garcia C, L. A. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna No. 140, Col. Los Pinos, 25253 Saltillo, Coahuila (Mexico); Velazquez S, J., E-mail: frrcarrillo@yahoo.com.mx [University of Texas at San Antonio, Department of Physics and Astronomy, San Antonio TX 78249 (United States)

    2015-07-01

    The extraction process of gold and silver by cyanidation generates large amounts of effluent which also contain contaminants such as cyanide and significant metal values such as copper. This paper presents the results of the removal and recovery of copper from ozonation treatment of a residual aqueous cyanide. The residual solution was treated by ozonation-precipitation to obtain a precipitate of copper. From this, copper nano composites obtained by Pechini modified sol-gel method were obtained. The compounds obtained were characterized by X-ray diffraction, showing a dependence of the type of compounds formed over time of ozonation and heat treatment of the gel. The particle size was measured by scanning electron microscopy and calculated by the Scherrer equation, being between 50 and 120 nm. (Author)

  9. Wide colour gamut generated in triply lanthanide doped sol-gel nano-glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, J. del, E-mail: fjvargas@ull.e [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Mendez-Ramos, J. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain); Yanes, A. C. [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Rodriguez, V. D. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain)

    2009-05-15

    The generation of a wide colour gamut, based on up-conversion of cheap near-infrared photons into the visible range, is of great importance for general lighting appliances and integrated optical devices. Here, we report for the first time on up-conversion luminescence under infrared excitation at 980 nm in Yb{sup 3+}-Er{sup 3+}-Tm{sup 3+} triply doped sol-gel derived SiO{sub 2}-LaF{sub 3} based nano-glass-ceramics (SOL-YET), containing LaF{sub 3} nanocrystals with a size about 13 nm. Efficient simultaneous up-conversion emission of the three primary colours (blue, green and red) gives rise to a balanced white overall emission. The ratio between up-conversion emission bands can be varied by changing pump power intensity resulting in colour tuneable up-conversion phosphor.

  10. Low temperature synthesis of magnesium oxide and spinel powders by a sol-gel process

    Directory of Open Access Journals (Sweden)

    Li-Zhai Pei

    2010-09-01

    Full Text Available Magnesium oxide and magnesium aluminate (MgAl2O4 spinel (MAS powders have been synthesized by a simple aqueous sol-gel process using citrate polymeric precursors derived from magnesium chloride, aluminium nitrate and citrate. The thermal decomposition of the precursors and subsequent formation of cubic MgO and MAS were investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, thermogravimetry-differential scanning calorimetry (TG-DSC and Fourier transform infrared spectra (FTIR. The single phase cubic MgO powder and MAS powder form after heat treatment at 800 and 1200 °C, respectively. The particle size of the MgO and MAS powders is about 100 nm and several micrometers, respectively. Ball milling eliminates the size of MgO and MgAl2O4 spinel powders by decreasing the conglomeration of the powders.

  11. Synthesis of Helical Phenolic Resin Bundles through a Sol-Gel Transcription Method

    Directory of Open Access Journals (Sweden)

    Changzhen Shao

    2017-02-01

    Full Text Available Chiral and helical polymers possess special helical structures and optical property, and may find applications in chiral catalysis and optical devices. This work presents the preparation and formation process of helical phenolic resins through a sol-gel transcription method. A pair of bola-type chiral low-molecular-weight gelators (LMWGs derived from valine are used as templates, while 2,4-dihydroxybenzoic acid and formaldehyde are used as precursors. The electron microscopy images show that the phenolic resins are single-handed helical bundles comprised of helical ultrafine nanofibers. The diffused reflection circular dichroism spectra indicate that the helical phenolic resins exhibit optical activity. A possible formation mechanism is proposed, which shows the co-assembly of the LMWGs and the precursors.

  12. Synthesis and Characterization of CZTS Thin Films by Sol-Gel Method without Sulfurization

    Directory of Open Access Journals (Sweden)

    Xiaoqi Yu

    2014-01-01

    Full Text Available One process of layer-by-layer sol-gel deposition without sulfurization was developed. The CZTS films with 1.2 μm and the sulfur ratio of ~48% were prepared and their characteristics were measured. The as-deposited and annealed films are of Kesterite structure. The as-deposited films do not present obvious electric conduction type. However, the annealed 9-LAY-ANN film is p-type conduction and has sheet resistance of 4.08 kΩ/□ and resistivity of 4.896 × 10−1 Ω·cm. The optic energy gap is 1.50 eV for as-deposited films and is 1.46 eV after being annealed. The region deposited by using Lo-Con solution is more compact than that by the Hi-Con solution from SEM morphology images.

  13. Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications

    Directory of Open Access Journals (Sweden)

    Alexis Fischer

    2013-03-01

    Full Text Available TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h. The morphological properties of the prepared films were analyzed by Scanning Electron Microscopy (SEM and Atomic Force Microscopy (AFM. The optical waveguiding properties of TiO2 films were investigated for both annealing temperature using m-lines spectroscopy. The refractive indices and the film thickness were determined from the measured effective indices. The results show that the synthesized planar waveguides are multimodes and demonstrate low propagation losses of 0.5 and 0.8 dB/cm for annealing temperature 350 and 500 °C, respectively.

  14. Sol-gel fabrication and optical absorption properties of C-NiO nanocomposite coatings

    CSIR Research Space (South Africa)

    Tile

    2010-12-01

    Full Text Available stream_source_info Tile1_2010.pdf.txt stream_content_type text/plain stream_size 1961 Content-Encoding ISO-8859-1 stream_name Tile1_2010.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Sol-gel fabrication and optical... absorption properties of C-NiO nanocomposite coatings Ngcali Tile1,2, Kittessa Roro1, Andrew Forbes1,2 1 CSIR National Laser Centre, Pretoria 2 School of physics, university of KwaZulu-Natal, Durban 0 200 400 600 800 1000 1200 0 0.2 0.4 0.6 0...

  15. Nanostructured porous sol-gel materials for applications in solar cells engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zakharchenko, R.V.; Diaz-Flores, L.L.; Perez-Robles, J.F.; Vorobiev, Y.V. [CINVESTAV-IPN, Unidad Queretaro, Libramiento Norponiente 2000, Juriquilla, Queretaro (Mexico); Gonzalez-Hernandez, J. [CIMAV, Miguel de Cervantes 120, Chihuahua (Mexico)

    2005-06-01

    Two nanostructured Sol-Gel composite materials for application in solar cells engineering were created and studied: the TiO{sub 2}/SiO{sub 2} films for antireflecting coatings of cells, and PMMA/SiO{sub 2} insulating layers on metal substrate for efficient heat extraction from a cell. Structural and optical investigation of the first composite proved that its parameters are adequate to serve the purpose; when doped with the dye absorbing UV light and emitting in the visible, it could also increase quantum yield of a cell. The second composite is designed for use in a hybrid PV/Thermal system, where it could optimize the heat exchange between a cell and solar plane collector, which also leads to an increase of efficiency of the system. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Organo-silica-titania nanocomposite elaborated by sol-gel processing with tunable optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Franc, J. [Laboratoire Traitement du Signal et Instrumentation, CNRS-UMR 5516, Universite Jean Monnet, 10 rue Barrouin, 42100 Saint-Etienne, 18 rue Benoit Lauras, F-42000 Saint-Etienne (France)]. E-mail: janyce.franc@univ-st-etienne.fr; Blanc, D. [Laboratoire Traitement du Signal et Instrumentation, CNRS-UMR 5516, Universite Jean Monnet, 10 rue Barrouin, 42100 Saint-Etienne, 18 rue Benoit Lauras, F-42000 Saint-Etienne (France); Zerroukhi, A. [Laboratoire de Rheologie des Matieres Plastiques, UMR CNRS 5156, 23 rue Paul Michelon, F-42023 Saint-Etienne Cedex 2 (France); Chalamet, Y. [Laboratoire de Rheologie des Matieres Plastiques, UMR CNRS 5156, 23 rue Paul Michelon, F-42023 Saint-Etienne Cedex 2 (France); Last, A. [Research Center Karlsruhe, Institute for Microstructure Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Destouches, N. [Laboratoire Traitement du Signal et Instrumentation, CNRS-UMR 5516, Universite Jean Monnet, 10 rue Barrouin, 42100 Saint-Etienne, 18 rue Benoit Lauras, F-42000 Saint-Etienne (France)

    2006-04-15

    Organically modified silica-titania thin films were elaborated by a sol-gel process and UV assisted photopolymerisation. Two different chelating agents, methacrylic acid (MAA) and a {beta}-diketone (2-(methacryloyloxy) ethyl acetoacetone (MAEA)) were compared in this work. It was demonstrated that the choice of the chelating agent is a key parameter to increase the molar ratio Si:Ti and therefore raise the refractive index of the material. {beta}-Diketone has proven to be a good candidate to stabilise the titanium precursor and its effects were compared to those observed with methacrylic acid. Fourier transform infrared spectroscopy was used to monitor the material formation and modification upon irradiation. M-lines spectroscopy was used to measure the refractive index of the material that varied between 1.51 and 1.59 depending on the titanium molar concentration. Optical properties were analysed in view of applications in the field of micro-optics and optical coatings.

  17. Large low-field magnetoresistance in nanocrystalline magnetite prepared by sol-gel method.

    Science.gov (United States)

    Lu, Z L; Zou, W Q; Lv, L Y; Liu, X C; Li, S D; Zhu, J M; Zhang, F M; Du, Y W

    2006-11-30

    Nanocrystalline magnetite Fe3O4 samples with a grain size of about 40 nm have been synthesized by an optimized sol-gel method. The single phase of spinel magnetite was confirmed by both X-ray diffraction and transmission electron microscopy. It has been found that the magnetoresistance of the samples at low field (LFMR) is relatively large, and with the decrease of temperature its value at a field of 0.5 T changes dramatically from -2.5% at 300 K to -17.0% at 55 K. With the further decrease of temperature a sharp drop occurs for the magnitude of the magnetoresistance (MR), regarded as a spin (cluster) glass transition in the surface region of the grains that can be confirmed by the zero-field-cooled and field-cooled magnetization and ac susceptibility measurement. The mechanism of the magnetic and transport properties was discussed.

  18. Microencapsulation of probiotic bacteria using thermo-sensitive sol-gel polymers for powdered infant formula.

    Science.gov (United States)

    Penhasi, Adel

    2015-01-01

    In this study the application of thermo-sensitive sol-gel polymers in microencapsulation formulation of probiotic bacteria, Bifidobacterium animalis spp lactis, for powdered infant formula (PIF), which is reconstituted at 70 °C, has been assessed. A double-layered microcapsule containing hydroxypropyl methyl cellulose (HPMC) as an inner layer and an outer layer, as the smart coating layer, based on a combination of hydroxypropyl cellulose (HPC) and poloxamer was designed. Generally, this specific microencapsulation provided superior protection against the reconstitution temperature. A high molecular weight of HPC and a greater thickness of the smart coating layer resulted in a delayed release of the bacteria from the microcapsules especially in the PIF composition. However, this was compensated by a high stability of the bacteria at 70 °C. Both the surface texture and particle size distribution of microcapsules have been respectively characterised by scanning electron microscopy and particle size analysis.

  19. Investigation of the Peroxovanadate Sol-Gel Process and Characterization of the Gels

    Energy Technology Data Exchange (ETDEWEB)

    Fontenot, Craig Joseph [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    In general, the peroxovanadate solution sol-gel process can be thought of as consisting of two parts: (1) the decomposition of the peroxo species and (2) cation hydrolysis leading to gelation. By controlling the synthesis conditions, both layered and amorphous compounds can be created. However, the type of water coordination observed in these gels was found to be identical no matter what the long-range order. The current work clarified many of the discrepancies found in the literature and offered much new valuable information. Highlights include the types of vanadium environments present at various stages of hydration, the role of adsorbed water, oxygen exchange from adsorbed water into the gel sites, and the ability to create metastable VMoO solid solution phases. These results could have a variety of impacts on future catalysis research.

  20. Fabrication and properties of nanocrystalline zinc oxide thin film prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Sumetha Suwanboon

    2008-01-01

    Full Text Available Zinc oxide (ZnO thin films were prepared on glass substrate by sol-gel dip-coating method. The structural properties were investigated by x-ray diffraction (XRD method and atomic force microscope (AFM. The optical properties were measured by UV-Vis spectrophotometer. The XRD patterns showed that the films formed preferred orientation along c-axis which increased as a function of polyvinyl pyrrolidone (PVP concentration. The films gave the crystallite size of 15-18 nm calculated by Scherrer’s formula and grain size of 48-70 nm measured by AFM at different PVP concentrations. The direct optical band gap of the films was in the range of 3.80-4.08 eV.

  1. Cultivation and energy efficient harvesting of microalgae using thermoreversible sol-gel transition

    Science.gov (United States)

    Estime, Bendy; Ren, Dacheng; Sureshkumar, Radhakrishna

    2017-01-01

    Microalgae represent a promising source of renewable biomass for the production of biofuels and valuable chemicals. However, energy efficient cultivation and harvesting technologies are necessary to improve economic viability. A Tris-Acetate-Phosphate-Pluronic (TAPP) medium that undergoes a thermoreversible sol-gel transition is developed to efficiently culture and harvest microalgae without affecting the productivity as compared to that in traditional culture in a well-mixed suspension. After seeding microalgae in the TAPP medium in a solution phase at 15 °C, the temperature is increased by 7 °C to induce gelation. Within the gel, microalgae are observed to grow in large clusters rather than as isolated cells. The settling velocity of the microalgal clusters is approximately ten times larger than that of individual cells cultured in typical solution media. Such clusters are easily harvested gravimetrically by decreasing the temperature to bring the medium to a solution phase.

  2. Europium incorporated in silica matrix obtained by sol-gel: luminescent materials

    Directory of Open Access Journals (Sweden)

    Nassar Eduardo José

    2003-01-01

    Full Text Available In this work we report some aspects of the chemistry involved in the preparation of modified silicon oxide by the sol-gel process. Europium III compounds were used as luminescent probe. An organic-inorganic hybrid was obtained by hydrolysis of tetraethylorthosilicate (TEOS and 3-aminopropyltriethoxysilane (APTS. The Eu III compounds were added in different ways. In the first, silica was prepared in the presence of Eu III, and in the second, Eu III was added on the silica surface. These materials were studied by luminescence, infrared spectroscopy and termogravimetric analysis. The results obtained for the hybrid material show different behavior for Eu III emission, which could be excited by the antenna effect and the influence of the surrounding in the luminescence quenching. The thermogravimetric data present different mass loss in samples to range temperature 50 - 150 °C. Thermogravimetric and infrared spectra showed that inorganic polymers incorporated the organic part.

  3. 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.

  4. Immobilized Aspergillus niger Lipase with SiO2 Nanoparticles in Sol-Gel Materials

    Directory of Open Access Journals (Sweden)

    Li Xu

    2016-09-01

    Full Text Available Lipase from Aspergillus niger was “doubly immobilized” with SiO2 nanoparticles in sol-gel powders prepared via the base-catalyzed polymerization of tetramethoxysilane (TMOS and methyltreimethoxysilane (MTMS. The hydrolytic activity of the immobilized lipase was measured using the p-nitrophenyl palmitate hydrolysis method. The results showed that the optimum preparation conditions for the gels were made using a MTMS/TMOS molar ratio of 5, 60 mg of SiO2 nanoparticles, a water/silane molar ratio of 12, 120 mg of enzyme supply, and 120 μL of PEG400. Under the optimal conditions, the immobilized lipase retained 92% of the loading protein and 94% of the total enzyme activity. Characteristic tests indicated that the immobilized lipase exhibited much higher thermal and pH stability than its free form, which shows great potential for industrial applications.

  5. Sol-gel methods for synthesis of aluminosilicates for dental applications.

    Science.gov (United States)

    Cestari, Alexandre

    2016-12-01

    Amorphous aluminosilicates glasses containing fluorine, phosphorus and calcium are used as a component of the glass ionomer dental cement. This cement is used as a restorative, basis or filling material, but presents lower mechanical resistance than resin-modified materials. The Sol-Gel method is a possible route for preparation of glasses with lower temperature and energy consumption, with higher homogeneity and with uniform and nanometric particles, compared to the industrial methods Glass ionomer cements with uniform, homogeneous and nanometric particles can present higher mechanical resistance than commercial ionomers. The aim of this work was to adapt the Sol-Gel methods to produce new aluminosilicate glass particles by non-hydrolytic, hydrolytic acid and hydrolytic basic routes, to improve glass ionomer cements characteristics. Three materials were synthesized with the same composition, to evaluate the properties of the glasses produced from the different methods, because multicomponent oxides are difficult to prepare with homogeneity. The objective was to develop a new route to produce new glass particles for ionomer cements with possible higher resistance. The particles were characterized by thermal analysis (TG, DTA, DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The glasses were tested with polyacrylic acid to form the glass ionomer cement by the setting reaction. It was possible to produce distinct materials for dental applications and a sample presented superior characteristics (homogeneity, nanometric particles, and homogenous elemental distribution) than commercial glasses for ionomer cements. The new route for glass production can possible improve the mechanical resistance of the ionomer cements. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Low temperature self-agglomeration of metallic Ag nanoparticles on silica sol-gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, O; Azimirad, R; Moshfegh, A Z [Department of Physics, Sharif University of Technology, PO Box 11155-9161, Tehran (Iran, Islamic Republic of)], E-mail: oakhavan@sharif.edu

    2008-10-07

    A facile sol-gel synthesis for self-agglomeration of metallic silver nanoparticles, with fcc crystalline structure, on the silica surface in a low annealing temperature has been introduced. X-ray photoelectron spectroscopy (XPS) revealed initial agglomeration ({approx}30 times greater than the nominal concentration of Ag) of the nanoparticles on the surface of the dried film (100 deg. C) and also their oxidation as well as easy diffusion (with 0.08 eV required activation energy) into the porous silica thin films, by increasing the annealing temperature (200-400 deg. C). By raising the Ag concentration from 0.2 to 1.6 mol% in the sol, the average size of the Ag nanoparticles increased from {approx}5 to 37 nm corresponding to a redshift of the optical plasmon resonance absorption peak from 404 to 467 nm. The high concentration of Ag (1.6 mol%) in the sol resulted in a rough surface containing compact nanoparticles. Using power spectral density analysis of the atomic force microscopy images, we have found that the highest contributions in the surface roughness of the dried silica films were caused by the particles ranging from {approx}62 to 159 nm. The particles smaller than {approx}39 nm did not show any detectable contributions in the surface roughness of the dried silica film. Based on the XPS analysis, a mechanism has also been proposed for the self-agglomeration of the Ag nanoparticles on the surface of the aqueous sol-gel silica thin films.

  7. Obtención de Cordierita por Sol-Gel a partir de fuentes nacionales cubanas

    Directory of Open Access Journals (Sweden)

    Pacheco, P.

    2003-10-01

    Full Text Available For cordierite synthesis through the Sol-Gel method, the sodium silicate obtained from the dissolution of a solid residue coming from the aluminum sulfate production based on kaolin, was used. The sources of magnesium and aluminum were obtained using the technologies previously developed by CIPIMM. The elements were mixed in a determined order and quantity to obtain a Gel with cordierite stechiometry. The gel was washed and dried and briquettes were made to treat them at different temperatures, obtaining cordierite in a major phase at 1200ºC. This was checked through the X-Ray diffraction analysis of the products coming from the thermical treatment. The method used when compared to the traditional ones, permitted to reduce crystallization temperature, obtaining more dense products and clean technology.

    Para la síntesis de la Cordierita por el método de Sol-Gel se utilizó, el silicato de sodio, obtenido de la disolución de un residuo sólido proveniente de la producción de sulfato de aluminio a partir de caolín. Los precursores de magnesio y aluminio fueron obtenidos utilizando las tecnologías previamente desarrolladas por el CIPIMM. Los materiales fueron mezclados en un orden y cantidad determinada hasta obtener el Gel con estequiometría de cordierita. El gel fue lavado, secado, briqueteado y tratado térmicamente a diferentes temperaturas, lográndose cordierita en fase mayoritaria a los 1200 ºC, lo cual fue corroborado mediante el análisis por difracción de rayos X de los productos del tratamiento térmico. El método utilizado comparado con los tradicionales permitió reducir la temperatura de cristalización, obtener productos más densificados y tecnología limpia.

  8. Responsive hydrogels produced via organic sol-gel chemistry for cell culture applications.

    Science.gov (United States)

    Patil, Smruti; Chaudhury, Pulkit; Clarizia, Lisa; McDonald, Melisenda; Reynaud, Emmanuelle; Gaines, Peter; Schmidt, Daniel F

    2012-08-01

    In this study, we report the synthesis of novel environmentally responsive polyurea hydrogel networks prepared via organic sol-gel chemistry and demonstrate that the networks can stabilize pH while releasing glucose both in simple aqueous media and in mammalian cell culture settings. Hydrogel formulations have been developed based on the combination of an aliphatic triisocyanate with pH-insensitive amine functional polyether and pH-sensitive poly(ethyleneimine) segments in a minimally toxic solvent suitable for the sol-gel reaction. The polyether component of the polyurea network is sufficiently hydrophilic to give rise to some level of swelling independent of environmental pH, while the poly(ethyleneimine) component contains tertiary amine groups providing pH sensitivity to the network in the form of enhanced swelling and release under acidic conditions. The reaction of these materials to form a network is rapid and requires no catalyst. The resultant material exhibits the desired pH-responsive swelling behavior and demonstrates its ability to simultaneously neutralize lactic acid and release glucose in both cell-free culture media and mammalian cell culture, with no detectable evidence of cytotoxicity or changes in cell behavior, in the case of either SA-13 human hybridomas or mouse embryonic stem cells. Furthermore, pH is observed to have a clear effect on the rate at which glucose is released from the hydrogel network. Such characteristics promise to maintain a favorable cell culture environment in the absence of human intervention. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Sol-Gel Deposition of Iridium Oxide for Biomedical Micro-Devices

    Directory of Open Access Journals (Sweden)

    Cuong M. Nguyen

    2015-02-01

    Full Text Available Flexible iridium oxide (IrOx-based micro-electrodes were fabricated on flexible polyimide substrates using a sol-gel deposition process for utilization as integrated pseudo-reference electrodes for bio-electrochemical sensing applications. The fabrication method yields reliable miniature on-probe IrOx electrodes with long lifetime, high stability and repeatability. Such sensors can be used for long-term measurements. Various dimensions of sol-gel iridium oxide electrodes including 1 mm × 1 mm, 500 µm × 500 µm, and 100 µm × 100 µm were fabricated. Sensor longevity and pH dependence were investigated by immersing the electrodes in hydrochloric acid, fetal bovine serum (FBS, and sodium hydroxide solutions for 30 days. Less pH dependent responses, compared to IrOx electrodes fabricated by electrochemical deposition processes, were measured at 58.8 ± 0.4 mV/pH, 53.8 ± 1.3 mV/pH and 48 ± 0.6 mV/pH, respectively. The on-probe IrOx pseudo-reference electrodes were utilized for dopamine sensing. The baseline responses of the sensors were higher than the one using an external Ag/AgCl reference electrode. Using IrOx reference electrodes integrated on the same probe with working electrodes eliminated the use of cytotoxic Ag/AgCl reference electrode without loss in sensitivity. This enables employing such sensors in long-term recording of concentrations of neurotransmitters in central nervous systems of animals and humans.

  10. Probing sol-gel matrices microenvironments by PGSE HR-MAS NMR.

    Science.gov (United States)

    Ferreira, Ana S D; Barreiros, Susana; Cabrita, Eurico J

    2017-05-01

    We applied Pulsed Gradient Spin Echo diffusion with high-resolution magic angle spinning NMR to study sol-gel matrices used to encapsulate enzymes for biocatalysis (TMOS/MTMS and TMOS/BTMS) to gain insight into the local chemical microenvironment. Transport properties of solvents with different polarities (1-pentanol, acetonitrile and n-hexane) were studied through their apparent self-diffusion coefficients. The spin echo attenuation of the solvents shows two distinct diffusion domains, one with fast diffusion (Dfast ) associated with interparticle diffusion and another with slow diffusion (Dslow ) corresponding to the displacement inside the pores within the sol-gel particles. The analysis of the root mean square displacements at different diffusion times showed that the Dfast domain has a free diffusion regime in both matrices (the root mean square displacement is linearly dependent of the diffusion time), while the Dslow domain shows a different regime that depends on the matrix. We investigated the exchange regime between the two diffusion sites. In both matrices, n-hexane was in intermediate exchange between diffusion domains, while the polar solvents were in slow exchange in TMOS/BTMS and in intermediate exchange in TMOS/MTMS. Data were fitted for TMOS/BTMS with the Kärger model, and the physical parameters were obtained. The results add to the evidence that the pores are a hydrophobic environment but that the presence of some free hydrophilic groups inside the pore, as observed in the TMOS/BTMS, has a key role in slowing down the exchange of polar solvents and that this is relevant to explain previously reported enzyme activity in these materials. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Nano rods for coloured glasses obtained by hybrid sol-gel coating.

    Science.gov (United States)

    Veron, Olivier; Blondeau, Jean-Philippe; Moineau, Johanne; Aubert, Pierre-Henri; Vignolle, Caroline Andreazza; Banet, Philippe; Allam, Lévi

    2011-09-01

    Many new materials are now allowing new properties thanks to nanotechnology because this domain of physics gives possibilities to optimize targeted properties even if these materials react in very various influential parameters. Architectural, automotive, bone pathologies, environment, display applications are some concerned domains. The sol-gel process is a method allowing the realisation of coats at ambiant temperature, thus it is possible to realize Liquid Crystal Display (LCD), water-repellent coatings on privacy glass, antireflective coatings, hydrophobic or hydrophilic surfaces, bone tissue regeneration. In this study, the purpose is to show the thermal influence on a covered glass with a complex hybrid sol-gel solution. This coated glass is going to change color from red to orange under the heat influence. This color change effect comes from the evolution of various compounds organizations then/or from their loss during the degassing sequence. We show in spite of the complexity of the process that the responsible is mainly the organic dye. Thus the structure of the heated glass at 250 degrees C looks radically different than the heated one at 350 degrees C. SEM measurement allows to identify the surface compositions and to determine the elementary composition along the sample's cross section. TGA is used to justify a mass loss when samples are annealed. UV/Visible measurement is realized by two methods: in-line transmission to evaluate luminous flux and thus give colorimetric dot in the normalized CIE diagram and diffuse transmission to observe the size influence of the pigments. Infrared Reflectivity allows to evaluate the influence of species on the structure and to better target the nature of the lost compounds during annealing. TEM measurement proves that the obtained iron particles are nano rods for both samples.

  12. Synthetic aspects and characterization of polypropylene-silica nanocomposites prepared via solid-state modification and sol-gel reactions

    NARCIS (Netherlands)

    Jain, S; Goossens, H; Picchioni, F; Magusin, P; Mezari, B

    2005-01-01

    A new route is developed by combining solid-state modification (SSM) by grafting vinyl triethoxysilane (VTES) with a sol-gel method to prepare PP/silica nanocomposites with varying degree of adhesion between filler and matrix. VTES was grafted via SSM in porous PP particles. Bulk polymerization

  13. Influence of the intermediate layer on the hydrothermal stability of sol-gel derived hybrid silica membranes

    NARCIS (Netherlands)

    ten Hove, Marcel; Luiten-Olieman, Mieke W.J.; Huiskes, Cindy; Nijmeijer, Arian; Winnubst, Louis

    2017-01-01

    The hydrothermal stability of microporous silica hybrid sol-gel derived membranes is often only tested for either the mesoporous intermediate membrane layer or the microporous separation layer. In this work an investigation is done on the interaction between the intermediate γ-alumina layer and the

  14. Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material.

    Science.gov (United States)

    Namnabat, Soha; Kim, Kyung-Jo; Jones, Adam; Himmelhuber, Roland; DeRose, Christopher T; Trotter, Douglas C; Starbuck, Andrew L; Pomerene, Andrew; Lentine, Anthony L; Norwood, Robert A

    2017-09-04

    Silicon photonics has gained interest for its potential to provide higher efficiency, bandwidth and reduced power consumption compared to electrical interconnects in datacenters and high performance computing environments. However, it is well known that silicon photonic devices suffer from temperature fluctuations due to silicon's high thermo-optic coefficient and therefore, temperature control in many applications is required. Here we present an athermal optical add-drop multiplexer fabricated from ring resonators. We used a sol-gel inorganic-organic hybrid material as an alternative to previously used materials such as polymers and titanium dioxide. In this work we studied the thermal curing parameters of the sol-gel and their effect on thermal wavelength shift of the rings. With this method, we were able to demonstrate a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization in ring resonators with waveguide widths of 325 nm when the sol-gel was cured at 130°C for 10.5 hours. We also achieved thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions. Curing time compared to curing temperature shows to be the most important factor to control sol-gel's thermo-optic value in order to obtain an athermal device in a wide temperature range.

  15. The application of silicon sol-gel technology to forensic blood substitute development: Mimicking aspects of whole human blood rheology.

    Science.gov (United States)

    Stotesbury, Theresa; Illes, Mike; Wilson, Paul; Vreugdenhil, Andrew J

    2017-01-01

    Solution-gelation chemistry has promising applications in forensic synthetic blood substitute development. This research offers a silicon-based sol-gel approach to creating stable materials that share similar rheological properties to that of whole human blood samples. Room temperature, high water content, silicon sol-gels were created using the organosilane precursors 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate along with various concentrations of filler and pigment. Shear-thinning non-Newtonian properties were observed within most formulations of the presented materials. The effects of colloidal concentration, temperature, age and filler addition on the viscosity of the sol-gels were investigated. SEM-EDS analysis was used to identify the behavior of the fillers within the film and support their inclusion for basic bloodstain pattern simulation. A final proposed candidate sol-gel was assessed using a previously reported passive drip simulation test on a hard, dry surface and passed. This works represents encouraging development in providing safe material alternatives to using whole human blood for forensic training and research. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. ELISA AND SOL-GEL BASED IMMUNOAFFINITY PURIFICATION OF THE PYRETHROID BIOALLETHRIN IN FOOD AND ENVIRONMENTAL SAMPLES

    Science.gov (United States)

    The peer-reviewed article describes the development of a new sol-gel based immunoaffinity purification procedure and an immunoassay for the pyrethroid bioallethrin. The immunoaffinity chromatography procedure was applied to food samples providing an efficient cleanup prior to im...

  17. Tailoring Wettability Through the Surface Modification of Electro-spun Polymers by Plasma and Sol-gel Treatments

    Science.gov (United States)

    2014-11-01

    nanoparticles , sol-gel reactions and by producing beads-on-a-string morphologies. Low surface energy was added by using fluorinated polymers, or through... nanoparticles ................................................................... 13 3.2.3 Effect of TEOS addition to electrospinning solutions...could benefit a number of applications: anti-biofouling; corrosion resistant paints for hulls; coatings that prevent ice buildup; water, stain and

  18. Modular bioink for 3D printing of biocompatible hydrogels : sol-gel polymerization of hybrid peptides and polymers

    NARCIS (Netherlands)

    Echalier, C.; Levato, R.; Mateos-Timoneda, Miguel A; Castaño, O.; Déjean, S.; Garric, X.; Pinese, C.; Noël, D.; Engel, E.; Martinez, J.; Mehdi, A.; Subra, G.

    2017-01-01

    An unprecedented generic system allowing the 3D printing of peptide-functionalized hydrogels by soft sol-gel inorganic polymerization is presented. Hybrid silylated inorganic/bioorganic blocks are mixed in biological buffer in an appropriate ratio, to yield a multicomponent bioink that can be

  19. Thermal stability of nanostructured titania and titania-ceria ceramic powders prepared by the sol-gel process

    NARCIS (Netherlands)

    Koebrugge, G.W.; Winnubst, Aloysius J.A.; Burggraaf, A.J.

    The preparation and characterisation of nanometre TiO2 powder materials, prepared by the sol-gel method, are described. Controlled hydrolysis of a titanium-2-methyl-2-butoxide precursor was applied to obtain alcosols with particles (in alcohol) smaller than 5 nm. Powders obtained from this sol were

  20. Sol-gel synthesis of ternary phosphate-ZrO2-SiO2 catalysts for alcohol dehydration

    National Research Council Canada - National Science Library

    Zhuang, Quan; Miller, Jack M

    2001-01-01

    ..., DRIFTS. Résumé : On a synthétisé des catalyseurs phosphate–ZrO 2 –SiO 2 par la méthode sol-gel utilisant du phosphite de triéthyle, du propylate de zirconium et de l’orthosilicate de té...

  1. Temperature annealing effect on structural and optical properties of ZnO thin films prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Elamal Bouzit S.

    2013-09-01

    Full Text Available ZnO thin films have been synthesized by sol-gel method. The effect of the annealing temperature on the morphological, structural and optical properties of the ZnO thin films was investigated. A good crystllinity and good transmittance in the visible spectrum was obtained at the annealing temperature of 400°C.

  2. Sol-Gel Application for Consolidating Stone: An Example of Project-Based Learning in a Physical Chemistry Lab

    Science.gov (United States)

    de los Santos, Desiree´ M.; Montes, Antonio; Sa´nchez-Coronilla, Antonio; Navas, Javier

    2014-01-01

    A Project Based Learning (PBL) methodology was used in the practical laboratories of the Advanced Physical Chemistry department. The project type proposed simulates "real research" focusing on sol-gel synthesis and the application of the obtained sol as a stone consolidant. Students were divided into small groups (2 to 3 students) to…

  3. ITO/Poly(Aniline/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Obeidi

    2013-01-01

    Full Text Available Described here is fabrication of a pH-sensitive, optically transparent transducer composed of a planar indium-tin oxide (ITO electrode overcoated with a poly(aniline (PANI thin film and a porous sol-gel layer. Adsorption of the PANI film renders the ITO electrode sensitive to pH, whereas the sol-gel spin-coated layer makes the upper surface compatible with fusion of phospholipid vesicles to form a planar supported lipid bilayer (PSLB. The response to changes in the pH of the buffer contacting the sol-gel/PANI/ITO electrode is pseudo-Nernstian with a slope of 52 mV/pH over a pH range of 4–9. Vesicle fusion forms a laterally continuous PSLB on the upper sol-gel surface that is fluid with a lateral lipid diffusion coefficient of 2.2 μm2/s measured by fluorescence recovery after photobleaching. Due to its lateral continuity and lack of defects, the PSLB blocks the pH response of the underlying electrode to changes in the pH of the overlying buffer. This architecture is simpler to fabricate than previously reported ITO electrodes derivatized for PSLB formation and should be useful for optical monitoring of proton transport across supported membranes derivatized with ionophores and ion channels.

  4. Effect of Aging Time and Film Thickness on the Photoelectrochemical Properties of TiO2 Sol-Gel Photoanodes

    Directory of Open Access Journals (Sweden)

    D. Regonini

    2014-01-01

    Full Text Available This work has focused on the investigation of a non-aqueous based sol-gel process to produce TiO2 based photoelectrodes for solar water splitting. In particular, the effect of the aging time of the sol and TiO2 film thickness on the photoelectrochemical properties of the photoanodes has been investigated. In order to achieve optimal performances (i.e., photocurrent density up to 570 µA/cm2 and IPCE of 26% at 300 nm, the sol needs to be aged for 3 to 6 h, before being dip-coated to produce the photoanodes. The importance of the aging time can also be appreciated from the optical properties of the TiO2 films; the absorbance threshold of the sol-gel aged for 3–6 h is slightly shifted towards longer wavelenghts in comparison to 0 h aging. Aging is necessary to build up a well-interconnected sol-gel network which finally leads to a photoelectrode with optimized light absorption and electron collection properties. This is also confirmed by the higher IPCE signal of aged photoelectrodes, especially below 340 nm. Among thicknesses considered, there is no apparent significant difference in the photoresponse (photocurrent density and IPCE of the TiO2 sol-gel films.

  5. Surface chemistry and moisture sorption properties of wood coated with multifunctional alkoxysilanes by sol-gel process

    Science.gov (United States)

    Mandla A. Tshabalala; Peter Kingshott; Mark R. VanLandingham; David Plackett

    2003-01-01

    Sol-gel surface deposition of a hydrophobic polysiloxane coating on wood was accomplished by using a mixture of a low molecular weight multifunctional alkoxysilane, methyltrimethoxysilane (MTMOS), and a high molecular weight multifunctional alkoxysilane, hexadecyltrimethoxysilane (HDTMOS). Investigation of the surface chemistry and morphology of the wood specimens by...

  6. 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...

  7. Preparation of gas-tight strontium-doped lanthanum cobaltate by an aqueous sol-gel process

    NARCIS (Netherlands)

    Chen, C.H.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Burggraaf, Anthonie; Burggraaf, A.J.

    1996-01-01

    Gas-tight dense membranes of highly Sr-doped LaCoO3 (such as the composition La0.3Sr0.7CoO3 chosen in this study) are difficult to prepare using usual synthesis processes. This report presents an aqueous sol-gel route using metal acetates as precursors to achieve this goal. Hydrogen peroxide and

  8. Organic-inorganic hybrid superhydrophobic surfaces using methyltriethoxysilane and tetraethoxysilane sol-gel derived materials in emulsion

    Science.gov (United States)

    Wen, Xiu-Fang; Wang, Kun; Pi, Pi-Hui; Yang, Jin-Xin; Cai, Zhi-Qi; Zhang, Li-juan; Qian, Yu; Yang, Zhuo-Ru; Zheng, Da-feng; Cheng, Jiang

    2011-11-01

    By applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) in organic siloxane modified polyacrylate emulsion (OSPA emulsion), we are able to demonstrate the potential for developing a sol-gel derived organic-inorganic hybrid emulsion for a superhydrophobic surface research. TEOS and MTES derived sol-gel moieties can be designed for a physical roughness and hydrophobic characteristic (Si-CH3) of the hybrid superhydrophobic surface, while OSPA emulsion can be endowed for good film-forming property. The effect of formulation parameters on superhydrophobicity and film-forming property was analyzed. The water contact angle (WCA) on the sol-gel derived hybrid film is determined to be 156°, and the contact angle hysteresis is 5° by keeping the mole ratio of TEOS:MTES:C2H5OH:NH3·H2O:AMP-95 at 1:4:30:10:0.63 and the mass percentage of OSPA emulsion at 25%. The nanoparticle-based silica rough surface is observed as the mole ratio of MTES/TEOS at 4:1. The sol-gel derived organic-inorganic hybrid emulsion shows remarkable film-forming property when the mole ratio of MTES/TEOS reaches or exceeds 4:1. With the primer coating, the performance of superhydrophobic film achieve actual use standard. It reveals that this new procedure is an effective shortcut to obtain a superhydrophobic surface with potential applications.

  9. Determinação de diagramas de bandas de energia e da borda de absorção em SnO2, depositado via sol-gel, sobre quartzo Determination of the band energy diagram and absorption fundamental edge in SnO2, deposited via sol-gel, on quartz

    Directory of Open Access Journals (Sweden)

    E. A. Floriano

    2009-03-01

    Full Text Available Propriedades ópticas e estruturais de filmes finos de SnO2, depositados sobre substratos de quartzo, são apresentadas. Os filmes são preparados pela técnica de molhamento via sol-gel. Uma avaliação das propriedades eletrônicas do cristal (bulk e das superfícies (110 e (101 do material é também efetuada, através de cálculos baseados em um método mecânico-quântico que utiliza a Teoria do Funcional da Densidade (DFT em conjunto com o funcional hibrido B3LYP. A borda fundamental de absorção, obtida experimentalmente, é então comparada com os diagramas de bandas de energia do bulk e superfícies (110 e (101, calculadas.Optical and structural properties of SnO2 thin films, deposited on quartz substrates, are presented. Films are prepared by the sol-gel-dip-coating technique. An evaluation of the electronic properties of bulk and surfaces (110 and (101 of the material is also carried out, through calculation based on a quantum-mechanical method using the Density Functional Theory (DFT in conjunction with the hybrid functional B3LYP. The absorption fundamental edge, experimentally obtained, is compared to the calculated band energy diagram of bulk and surfaces (110 and (101.

  10. 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.

  11. Evaluation of sol-gel based magnetic 45S5 bioglass and bioglass-ceramics containing iron oxide.

    Science.gov (United States)

    Shankhwar, Nisha; Srinivasan, A

    2016-05-01

    Multicomponent oxide powders with nominal compositions of (45-x)·SiO2·24.5CaO·24.5Na2O·6P2O5xFe2O3 (in wt.%) were prepared by a modified sol-gel procedure. X-ray diffraction (XRD) patterns and high resolution transmission electron microscope images of the sol-gel products show fully amorphous structure for Fe2O3 substitutions up to 2 wt.%. Sol-gel derived 43SiO2·24.5CaO·24.5Na2O·6P2O5·2Fe2O3 glass (or bioglass 45S5 with SiO2 substituted with 2 wt.% Fe2O3), exhibited magnetic behavior with a coercive field of 21 Oe, hysteresis loop area of 33.25 erg/g and saturation magnetization of 0.66 emu/g at an applied field of 15 kOe at room temperature. XRD pattern of this glass annealed at 850 °C for 1h revealed the formation of a glass-ceramic containing sodium calcium silicate and magnetite phases in nanocrystalline form. Temperature dependent magnetization and room temperature electron spin resonance data have been used to obtain information on the magnetic phase and distribution of iron ions in the sol-gel glass and glass-ceramic samples. Sol-gel derived glass and glass-ceramic exhibit in-vitro bioactivity by forming a hydroxyapatite surface layer under simulated physiological conditions and their bio-response is superior to their melt quenched bulk counterparts. This new form of magnetic bioglass and bioglass ceramics opens up new and more effective biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Refractive and diffractive micro-optical elements and arrays prepared by the fast sol-gel processes

    Science.gov (United States)

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

    1997-09-01

    The optical quality of films and bulk elements obtained by the fast sol-gel method and the ease of preparation make this method technologically and economically attractive for micro- optical elements and arrays. Multiple replication of high-cost metal templates necessitates a two step process: initial replication onto disposable plastic, to produce negative- templates, and casting of the glass elements onto these plastic templates. Following introduction of the fast sol-gel micro-replication processes, the fabrication of refractive and diffractive micro-optical arrays is described in detail. The study focuses of the accuracy achievable by the replication of sharp curvatures by a viscous sol-gel resins. A further question addressed is how to obtain a thick crack-free self- supporting micro-optical array by such a process. Examples of replication results of Fresnel lenses and various types of lenslet arrays by this method are shown, and the various aspects of replication accuracy are discussed. The characterization of the thus produced micro-optical arrays is described, relating to the influence of mold and resin parameters on residual stresses and thence, the surface and bulk properties of the replicas. Various approaches to stress- minimization that can facilitate accurate replication in sol- gel derived matrices are discussed. Further, the preparative approach to highly patterned crack-free self-supporting thick elements is displayed, and the wide scope of new applications stemming from such elements is discussed. Finally, the new chemical approach to crack-free stress-free silica glasses by the sol-gel method is displayed.

  13. Rapid synthesis of titania-silica nanoparticles photocatalyst by a modified sol-gel method for cyanide degradation and heavy metals removal

    Energy Technology Data Exchange (ETDEWEB)

    Harraz, Farid A., E-mail: fharraz@cmrdi.sci.eg [Nanostructured Materials and Nanotechnology Division, Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87 Helwan, Cairo 11421 (Egypt); Abdel-Salam, Omar E. [Faculty of Engineering, Cairo University, Giza (Egypt); Mostafa, Ahlam A. [Aircraft Factory, Helwan (Egypt); Mohamed, Reda M. [Nanostructured Materials and Nanotechnology Division, Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87 Helwan, Cairo 11421 (Egypt); Faculty of Science, King Abdulaziz University (Saudi Arabia); Hanafy, M. [Faculty of Engineering, Cairo University, Giza (Egypt)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer TiO{sub 2}-SiO{sub 2} photocatalyst was prepared by a modified sol-gel technique. Black-Right-Pointing-Pointer The modified TiO{sub 2}-SiO{sub 2} catalyst shows remarkable photocatalytic activity. Black-Right-Pointing-Pointer Complete degradation of cyanide and removal of Cr, Co, Pb were achieved. Black-Right-Pointing-Pointer Catalytic performance depends essentially on catalyst, target and reaction time. - Abstract: Titania-silica (TiO{sub 2}-SiO{sub 2}) photocatalyst was prepared by a modified sol-gel technique. Titania sol was firstly synthesized by acid hydrolysis of a TiCl{sub 4} precursor instead of titanium alkoxides. The titania sol was further modified with SiO{sub 2} to obtain a modified catalyst. The as-prepared TiO{sub 2}-SiO{sub 2} catalyst demonstrated a remarkable photocatalytic activity toward degradation of cyanide and heavy metals removal (Cr(III), Co(II) and Pb(II)). The influence of the preparation parameters; the reaction time, the calcination temperature and time, the [H{sup +}]/[Ti] ratio, the pH value and the acid concentration on the structural and chemical properties of the catalyst was investigated in details. The catalytic performance was found to depend essentially on the catalyst and target concentrations and the reaction time. The as-synthesized catalyst was characterized by a variety of techniques including surface area measurement, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) spectroscopy measurements. Results of the synthesis and characterization of TiO{sub 2}-SiO{sub 2} catalyst and its photocatalytic performance are presented and thoroughly discussed.

  14. A novel tantalum-based sol-gel packed microextraction syringe for highly specific enrichment of phosphopeptides in MALDI-MS applications.

    Science.gov (United States)

    Çelikbıçak, Ömür; Atakay, Mehmet; Güler, Ülkü; Salih, Bekir

    2013-08-07

    A new tantalum-based sol-gel material was synthesized using a unique sol-gel synthesis pathway by PEG incorporation into the sol-gel structure without performing a calcination step. This improved its chemical and physical properties for the high capacity and selective enrichment of phosphopeptides from protein digests in complex biological media. The specificity of the tantalum-based sol-gel material for phosphopeptides was evaluated and compared with tantalum(V) oxide (Ta2O5) in different phosphopeptide enrichment applications. The tantalum-based sol-gel and tantalum(V) oxide were characterized in detail using FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and also using a surface area and pore size analyzer. In the characterization studies, the surface morphology, pore volume, crystallinity of the materials and PEG incorporation into the sol-gel structure to produce a more hydrophilic material were successfully demonstrated. The X-ray diffractograms of the two different materials were compared and it was noted that the broad signals of the tantalum-based sol-gel clearly represented the amorphous structure of the sol-gel material, which was more likely to create enough surface area and to provide more accessible tantalum atoms for phosphopeptides to be easily adsorbed when compared with the neat and more crystalline structure of Ta2O5. Therefore, the phosphopeptide enrichment performance of the tantalum-based sol-gels was found to be remarkably higher than the more crystalline Ta2O5 in our studies. Phosphopeptides at femtomole levels could be selectively enriched using the tantalum-based sol-gel and detected with a higher signal-to-noise ratio by matrix-assisted laser desorption/ionization-mass spectrometer (MALDI-MS). Moreover, phosphopeptides in a tryptic digest of non-fat bovine milk as a complex real-world biological sample were retained with higher yield using a tantalum-based sol-gel. Additionally, the sol-gel material

  15. Enhanced electrical properties in sub-10-nm WO3 nanoflakes prepared via a two-step sol-gel-exfoliation method

    Science.gov (United States)

    2014-01-01

    The morphology and electrical properties of orthorhombic β-WO3 nanoflakes with thickness of ~7 to 9 nm were investigated at the nanoscale with a combination of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), current sensing force spectroscopy atomic force microscopy (CSFS-AFM, or PeakForce TUNA™), Fourier transform infra-red absorption spectroscopy (FTIR), linear sweep voltammetry (LSV) and Raman spectroscopy techniques. CSFS-AFM analysis established good correlation between the topography of the developed nanostructures and various features of WO3 nanoflakes synthesized via a two-step sol-gel-exfoliation method. It was determined that β-WO3 nanoflakes annealed at 550°C possess distinguished and exceptional thickness-dependent properties in comparison with the bulk, micro and nanostructured WO3 synthesized at alternative temperatures. PMID:25221453

  16. Transesterification of babassu oil catalyzed by Burkholderia cepacia encapsulated in sol-gel matrix employing protic ionic liquid as an additive

    Directory of Open Access Journals (Sweden)

    Maria Vanessa Souza Oliveira

    2014-02-01

    Full Text Available Enzymatic transesterification from non-edible vegetable oil (babassu oil and ethanol is provided. A set of seven experiments featuring a full 22 factorial design with three central points and different combinations of molar ratio and temperature as independent variables was employed. Transesterification reactions were catalyzed by Burkholderia cepacia lipase encapsulated in a hydrophobic matrix obtained by the sol-gel technique using protic ionic liquid (N-methylmonoethanolamine pentanoate as additive and with conventional heating (40 – 56°C. Ethyl esters highest yield (51.90% was obtained by experimental design with 1:7 molar ratio (oil:alcohol and temperature at 40°C during 48h reaction. The process with a 5-fold increase of enzymatic load provided 98.69% ethyl esters yield with 4.29 mm2 s-1 viscosity

  17. Titanium modified with layer-by-layer sol-gel tantalum oxide and an organodiphosphonic acid: a coating for hydroxyapatite growth.

    Science.gov (United States)

    Arnould, C; Volcke, C; Lamarque, C; Thiry, P A; Delhalle, J; Mekhalif, Z

    2009-08-15

    Titanium and its alloys are widely used in surgical implants due to their appropriate properties like corrosion resistance, biocompatibility, and load bearing. Unfortunately when metals are used for orthopedic and dental implants there is the possibility of loosening over a long period of time. Surface modification is a good way to counter this problem. A thin tantalum oxide layer obtained by layer-by-layer (LBL) sol-gel deposition on top of a titanium surface is expected to improve biocorrosion resistance in the body fluid, biocompatibility, and radio-opacity. This elaboration step is followed by a modification of the tantalum oxide surface with an organodiphosphonic acid self-assembled monolayer, capable of chemically binding to the oxide surface, and also improving hydroxyapatite growth. The different steps of this proposed process are characterized by surfaces techniques like contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).

  18. Some of Physical Properties of Nanostructured (Mg1-xCoxFe2O4 Ferrites Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Muhammad Abdul Ammer Alsherefi

    2018-01-01

    Full Text Available Sol-gel auto combustion technique was used to prepare nanoparticles of magnesium-cobalt ferrites with the chemical formula Mg1-xCoxFe2O4 for  (x=0, 0.2, 0.4, 0.6, 0.8, 1, where x added as weight  percentages, and sintering  at temperature (1100 oC. The X-ray patterns of prepared powder has confirmed the structure of cubic spinel structure (fcc. The prepared samples were composed of nearly spherical nano particles .An average particle size of  magnesium-cobalt ferrite  were  calculated  using  Debye Scherer’s relation is equal 53.12 nm. The surface structure of the samples was investigated by Scanning Electron Microscope(SEM. The electromagnetic properties for prepared samples were investigated using Vector Network Analyzer (VNA in X-band microwave region.

  19. Photocatalytic oxidation of toluene in presence of water vapor using sol-gel synthesized N-doped TiO2

    Science.gov (United States)

    Van Sau, Nguyen; An, Ngo Thanh; Long, Nguyen Quang

    2017-09-01

    Toluene removal by photocatalytic oxidation in presence of water vapor was investigated on N-doped TiO2. The photocatalyst was prepared by a sol-gel method and characterized by various techniques. The conversion of toluene by photocatalytic oxidation in the presence of water vapor was reported at different reaction conditions, such as various reaction temperatures, various toluene/ water vapor concentrations. By using Langmuir- Hinshelwood model the activation energy (Ea) of the reaction of 1.33 kcal/mol was obtained. The heat of toluene adsorption and the heat of water vapor adsorption on the N-doped TiO2 catalyst were approximately -3.47 kcal/mol and -3.30 kcal/mol, respectively.

  20. Sol-gel deposited aluminum-doped and gallium-doped zinc oxide thin-film transparent conductive electrodes with a protective coating of reduced graphene oxide

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2016-04-01

    Using a traditional sol-gel deposition technique, we successfully fabricated aluminum-doped zinc oxide (AZO) and gallium-doped zinc oxide (GZO) thin films on glass substrates. Employing a plasma treatment method as the postannealing process, we produced thin-film transparent conductive electrodes exhibiting excellent optical and electrical properties, with transmittance greater than 90% across the entire visible spectrum and the near-infrared range, as well as good sheet resistance under 200 Ω/sq. More importantly, to improve the resilience of our fabricated thin-film samples at elevated temperatures and in humid environments, we deposited a layer of reduced graphene oxide (rGO) as protective overcoating. The stability of our composite AZO/rGO and GZO/rGO samples improved substantially compared to that of their counterparts with no rGO coating.

  1. TiO2 sol-gel thin films containing Au and Pt nanoparticles with controlled morphology: optical study and gas sensing properties

    Science.gov (United States)

    Della Gaspera, Enrico; Buso, Dario; Post, Michael L.; Martucci, Alessandro

    2010-04-01

    Au and Pt nanoparticles are prepared with colloidal techniques in order to achieve high morphological quality, capped with a polymer and then embedded inside a TiO2 sol-gel matrix, resulting in a homogeneous dispersion of both metal colloids, confirmed by TEM analyses. Refractive index values measured with ellipsometry increase with the annealing temperature, with quite a linear trend, and at the same time the Au surface plasmon resonance peak undergoes a red shift: the refractive index evaluated from the Au plasmon band is slightly lower than the measured value, indicating that the refractive index just around metal particles is different from the average of the matrix, likely because of the polymeric capping agent. Optical gas sensing tests towards CO and H2 are presented as one of the possible applications of these nanocomposites.

  2. Yellow emission of SiO2/Zn2SiO4:Mn nanocomposite synthesized by sol-gel method

    Science.gov (United States)

    El Mir, L.; Omri, K.; El Ghoul, J.; AL-Hobaib, A. S.; Dahman, H.; Barthou, C.

    2014-01-01

    A two-step sol-gel process was used for the preparation of Mn doped β -Zn2SiO4 nanoparticles embedded in silica host matrix after the incorporation of ZnO:Mn nanoparticles in silica monolith. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the phase purity, particle size and morphology. XRD results indicate that pure phase of β -Zn2SiO4 with triclinic structure was obtained after thermal treatment at 1500 °C. However, photoluminescence (PL) technique was investigated for optical study. It was illustrated that the Mn doping content influenced the degree of aggregation and luminescence of the nanocomposite. This manganese doped zinc silica phase in silica host matrix, exhibit yellow emission centred at about 575 nm driven by 4T1 to 6A1 relaxation in Mn2+. The crystallinity and luminescent property of nanocomposite were investigated.

  3. Recubrimientos sol-gel obtenidos por deposición electroforética (EPD sobre metales

    Directory of Open Access Journals (Sweden)

    Castro, Y.

    2000-12-01

    Full Text Available Sol-gel process is a suitable method for the production of glass-like coatings onto metals, acting as barrier against oxidation and providing an increased resistance to corrosion. Hybrid and inorganic coatings of different compositions have been used for coating several metals by using techniques like dipping, spin-coating and spraying. Although these methods lead to good properties the final coatings are restricted by the thin thickness (up to 2 μm, thus limiting the application range. Electrophoretic deposition (EPD is considered a highly versatile technique for producing homogeneous thicker coatings. The aim of this work deals with the preparation of coatings onto metals by EPD from hybrid silica sols (TEOS, MTES and from colloidal silica suspensions where the hybrid sols constitute the suspending medium. Both the solutions and the suspensions have been studied in terms of viscosity, density and conductivity. Furthermore, the physical parameters associated to EPD, such as deposition time and current density, have been also studied, taking into account the additional contribution to the layer formed by EPD occurring by dipping during withdrawal. The coatings obtained by dipping and by EPD have been characterised by perfilometry and optical microscopy.

    El proceso sol-gel es un método de gran interés para la producción de películas vítreas sobre metales, que actúan como barrera protectora frente a la oxidación y aumentan su resistencia a la corrosión. Se han obtenido recubrimientos inorgánicos e híbridos de distintas composiciones sobre distintos metales usando técnicas como inmersión, centrifugado y pulverización. Aunque estos métodos proporcionan recubrimientos con buenas propiedades los espesores obtenidos son bajos (inferiores a 2 mm, lo que limita sus posibilidades de aplicación. La deposición electroforética (EPD se perfila como una técnica de gran versatilidad para la obtención de recubrimientos homogéneos de

  4. Epitaxial growth of Sc-doped ZnO films on Si by sol-gel route

    Science.gov (United States)

    Sharma, Ruchika; Sehrawat, Kiran; Wakahara, Akihiro; Mehra, R. M.

    2009-03-01

    The epitaxial growth of doped ZnO films is of great technological importance. Present paper reports a detailed investigation of Sc-doped ZnO films grown on (1 0 0) silicon p-type substrates. The films were deposited by sol-gel technique using zinc acetate dihydrate as precursor, 2-methoxyethanol as solvent and monoethanolamine (MEA) as a stabilizer. Scandium was introduced as dopant in the solution by taking 0.5 wt% of scandium nitrate hexahydrate. The effect of annealing on structural and photoluminescence properties of nano-textured Sc-doped films was investigated in the temperature range of 300-550 °C. Structural investigations were carried out using X-ray diffraction, scanning electron microscopy and atomic force microscopy. X-ray diffraction study revealed that highly c-axis oriented films with full-width half maximum of 0.21° are obtained at an annealing temperature of 400 °C. The SEM images of ZnO:Sc films have revealed that coalescence of ZnO grains occurs due to annealing. Ostwald ripening was found to be the dominant mass transport mechanism in the coalescence process. A surface roughness of 4.7 nm and packing density of 0.93 were observed for the films annealed at 400 °C. Room temperature photoluminescence (PL) measurements of ZnO:Sc films annealed at 400 °C showed ultraviolet peak at about (382 nm) with FWHM of 141 meV, which are comparable to those found in high-quality ZnO films. The films annealed below or above 400 °C exhibited green emission as well. The presence of green emission has been correlated with the structural changes due to annealing. Reflection high energy electron diffraction pattern confirmed the nearly epitaxial growth of the films. Ruchika Sharma, P. K. Shishodia, A. Wakahara and R. M. Mehra, Materials Science-Poland 27 (2009) Ist issue.

  5. Quartz Crystal Microbalance Coated with Sol-gel-derived Thin Films as Gas Sensor for NO Detection

    Directory of Open Access Journals (Sweden)

    S. J. O’Shea

    2003-10-01

    Full Text Available This paper presents the possibilities and properties of Indium tin oxide (ITO-covered quartz crystal as a NOx toxic gas-sensor. The starting sol-gel solution was prepared by mixing indium chloride dissolved in acetylacetone and tin chloride dissolved in ethanol (0-20% by weight. The ITO thin films were deposited on the gold electrodes of quartz crystal by spin-coating technique and subsequently followed a standard photolithography to pattern the derived films to ensure all sensors with the same sensing areas. All heat treatment processes were controlled below 500°C in order to avoid the piezoelectric characteristics degradation of quartz crystal (Quartz will lose its piezoelectricity at ~573°C due to the phase change from α to β. The electrical and structural properties of ITO thin films were characterized with Hall analysis system, TG/DTA, XRD, XPS, SEM and etc. The gas sensor had featured with ITO thin films of ~100nm as the receptor to sense the toxic gas NO and quartz crystal with frequency of 10MHz as the transducer to transfer the surface reactions (mass loading, etc into the frequency shift. A homemade setup had been employed to measure the sensor response under the static mode. The experimental results had indicated that the ITO-coated QCM had a good sensitivity for NO gas, ~12Hz/100ppm within 5mins. These results prove that the ITO-covered quartz crystals are usable as a gas sensor and as an analytical device.

  6. Preparasi dan karakterisasi fotokatalis NaTaO3 didoping ion lantanum (La/NaTaO3 dengan metode sol-gel

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    Husni Husin

    2011-12-01

    Full Text Available Crystalline sodium tantalate doped with La3+ ions (La/NaTaO3 has been successfully synthesized by sol-gel technique. The photocatalysts have been prepared by mixing of TaCl5, NaOH, and La(NO33.2H2O in the aqueous solution of H2O2. The resulting materials are characterized by X-ray diffraction (XRD, Brunauer-Emmett-Teller (BET, and transmission electron microscopy (TEM to provide useful information about crystallinity and morphology. All samples are exactly indexed as the pure NaTaO3 orthorhombic structure with the space group Pcmn. The XRD spectra displayed a single-phase NaTaO3 structure without any impurity phase, suggesting that lanthanum is uniformly incorporated into the NaTaO3 lattice. TEM images indicates that the particle sizes of the La-doped NaTaO3 powders are approximately 30-80 nm, while the particle sizes of the non-doped NaTaO3 are around 80-250 nm. Doping lanthanum in the NaTaO3 is able to prevent agglomeration, result in particle size, and better crystallinity. The La/NaTaO3 crystal structures reveal that a certain amount of lattice distortion due to the La3+ ions occupying the Na+ sites results in the increase of crystallite size. Powder formation mechanisms for both non-doped NaTaO3 and La-doped NaTaO3 are proposed based on the experimental results. Keywords: La-doped sodium tantalum oxide, photocatalyst, sol-gel, perovskite, orthorhombic

  7. Two schemes for production of biosurfactant from Pseudomonas aeruginosa MR01: Applying residues from soybean oil industry and silica sol-gel immobilized cells.

    Science.gov (United States)

    Bagheri Lotfabad, Tayebe; Ebadipour, Negisa; Roostaazad, Reza; Partovi, Maryam; Bahmaei, Manochehr

    2017-04-01

    Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover, rhamnolipid mixtures extracted from different cultures showed critical micelle concentrations (CMC) in the range of ≃24 to ≃36mg/l with capability to reduce the surface tension of aqueous solution from 72 to ≃27-32mN/m. However, the sol-gel technique using tetraethyl orthosilicate (TEOS) was used as a gentler method in order to entrap the P. aeruginosa MR01 cells in mold silica gels. Immobilized cells can be utilized several times in consecutive fermentation batches as well as in flow fermentation processes. In this way, reusability of the cells may lead to a more economical fermentation process. Approximately 90% of cell viability was retained during the silica sol-gel immobilization and ≃84% of viability of immobilized cells was preserved for 365days of immobilization and storage of the cells in phosphate buffer at 4°C and 25°C. Moreover, mold gels showed good mechanical stability during the seven successive fermentation batches and the entrapped cells were able to efficiently preserve their biosurfactant-producing potential. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Synthesis and Characterization of ZnO/Bi2O3 Core/Shell Nanoparticles by the Sol-Gel Method

    Science.gov (United States)

    Liu, Ting-Ting; Wang, Mao-hua; Zhang, Han-Ping

    2016-08-01

    In this work, a novel two-step synthesis of ZnO/Bi2O3 core/shell nanoparticles is presented. Spherical core particles of ZnO were first synthesized by a 95°C direct precipitation method with the assistance of polyethylene glycol (PEG-6000) surfactants, and then used as precursors to prepare ZnO/Bi2O3 core/shell particles via a 70°C low-temperature sol-gel method. Techniques including x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy and scanning electron microscopy were employed to characterize the as-synthesized samples. The ZnO nanoparticles were almost spherical in shape, with particle size ranging from 15 nm to 28 nm, and belonged to a hexagonal wurtzite crystal structure. Furthermore, the experimental result showed that ZnO nanoparticles were fully covered with Bi2O3. In addition, using ZnO/Bi2O3 core/shell nanoparticles (1 mol.% Bi2O3) via this sol-gel method, after sintering in air at 1100°C for 2 h, the varistors showed maximum relative density of 96.6%, with high breakdown voltage (2191 ± 0.72 V/cm), low leakage current (0.12 ± 0.07 μA) and nonlinear coefficient (6 ± 0.14), suggesting that nano-coating is a promising route for the preparation of ZnO varistors.

  9. Structural and magnetic properties of yttrium iron garnet (YIG and yttrium aluminum iron garnet (YAlG nanoferrite via sol-gel synthesis

    Directory of Open Access Journals (Sweden)

    Makiyyu Abdullahi Musa

    Full Text Available The structural and magnetic properties of yttrium iron garnet (YIG and yttrium aluminum iron garnet (Y3AlxFe5−xO12, YAIG (x = 0.2, 0.6, 1, 1.4, 1.8, and 2.2 nanoparticles were investigated. The samples were prepared via auto combustion sol-gel technique, using citric acid as chelating agent and fuel for the combustion process. The obtained powder was heated at 950 °C. X-ray diffraction peaks confirmed the garnet phase formation. Crystallite size increases with Al from 28.5894 to 28.6170 nm. Lattice constant of the samples was found to decrease from 12.4674 Å to 12.3233 Å as Al increase from 0.0 to 2.2. FTIR was used to confirm the garnet structure, the main vibrating modes were observed to shift to higher wave number with increasing Al concentration. Saturation magnetization, Ms shows a decreasing trend from 20.721 to 0.7586 emu/g with increasing Al from 0.0 to 2.2. Furthermore, the decreasing trends in the static magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. High content of Al substitution on YIG leads to paramagnetic behavior of the ferrite. The grain size decreased from 0.64 μm to 0.32 μm, while the bulk density decreased from 5.058 gcm−3 to 4.233 gcm−3 as Al increase from 0.0 to 2.2. Keywords: YIG, YAIG, Sol-gel, Phase composition, Magnetic properties

  10. Correlation between microstructure and optical properties of nano-crystalline TiO{sub 2} thin films prepared by sol-gel dip coating

    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); Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria); Sedrine, N. Ben; 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); Bensaha, R. [Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria)

    2010-11-15

    Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO{sub 2} thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO{sub 2} thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO{sub 2} thin films. The results show that the TiO{sub 2} thin films crystallize in anatase phase between 400 and 800 deg. C, and into the anatase-rutile phase at 1000 deg. C, and further into the rutile phase at 1200 deg. C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO{sub 2} thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 deg. C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

  11. Structural and optical properties of Eu3+/Gd3+ ions in silica xerogels and powders obtained by sol-gel method

    Science.gov (United States)

    Pawlik, Natalia; Szpikowska-Sroka, Barbara; Swinarew, Andrzej S.; Łężniak, Marta; Pisarski, Wojciech A.

    2016-12-01

    The xerogels and sol-gel powders with different quantitative composition have been studied based on excitation and emission measurements as well as luminescence decay analysis. The structure of prepared silica sol-gel materials was examined using FT-IR spectroscopy technique. The photoluminescence spectra of Eu3+ ions were registered upon two different excitation wavelengths related to direct excitation of Eu3+ ions (λexc = 393 nm) and indirect excitation through energy transfer process from Gd3+ to Eu3+ (λexc = 273 nm). Upon direct excitation of Eu3+ (7F0 → 5L6 transition) the characteristic emission bands assigned to the 5D0 → 7FJ(0-4) electronic transitions were observed. Also, it was found that enhanced luminescence of Eu3+ is a result of change the excitation parameter through energy transfer phenomenon (8S7/2 → 6IJ transition of Gd3+) and occurred in both xerogels and powder samples. In this way, a UV photon absorbed by Gd3+ is converted into visible light emitted by Eu3+ ions. Obtained results clearly indicated that high concentration of Gd3+ ions in powders led to particularly strong enhance the emission in red spectral range and allowed for more than 12-times prolongation of luminescence lifetime for the 5D0 excited state of Eu3+ compared to silica xerogel samples. The values of energy transfer efficiency were also estimated based on luminescence decay times of the 6P7/2 state of Gd3+ ions.

  12. Investigation of sol-gel transition by rheological methods. Part I. Experimental methods.

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2017-08-01

    Full Text Available In this work rheological studies of the gelling process were carried out. We have developed a measuring system for studying the rheology of the gelation process. It consisted of several measuring cells of the Weiler-Rebinder type, system for automatic regulation of the composition of the medium and hermostabilization system. This complex is designed to measure the dependence of the value of the ultimate shear stress as a function of time, from the start of the sol-gel transition to the complete conversion of the sol to the gel. The developed device has a wide range of measured values of critical shear stresses τ0 = (0,05÷50000 Dyne/cm2. Using the developed instrument, it was possible to establish the shape of the initial section of the curve τ0 = f(t and develop a methodology for more accurate determination of gelation time. The developed method proved that the classical method for determining the start time of the sol-gel transition using the point of intersection of the tangent to the linear part of the rheological curve τ0 = f(t,gives significantly distorted results. A new phenomenon has been discovered: the kinetic curves in the coordinates of the Avrami-Erofeev-Bogolyubov equation have an inflection point which separates the kinetic curve into two parts, the initial and the final. It was found that the constant k in the Avrami–Erofeev–Bogolyubov quation does not depend on the temperature and is the same for both the initial and final parts of the kinetic curve. It depends only on the chemical nature of the reacting system. It was found that for the initial section of the kinetic curves, the value of the parameter n in the Avrami-Erofeev-Bogolyubov equation was n = 23,4±2,8 and, unlike the final section of the rheological curve, does not depend on temperature. A large value of this parameter can be interpreted as the average number of directions of growth of a fractal aggregate during its growth. The value of this parameter depends

  13. Effects of sol-gel processed silica coating on bond strength of resin cements to glass-infiltrated alumina ceramic.

    Science.gov (United States)

    Xie, Haifeng; Wang, Xiaozu; Wang, Yu; Zhang, Feimin; Chen, Chen; Xia, Yang

    2009-02-01

    The aim of this study was to verify the effects of sol-gel processed silica coating on the bond strength between resin cement and glass-infiltrated aluminum oxide ceramic. Silica coatings were prepared on glass-infiltrated aluminum oxide ceramic surface via the sol-gel process. Atomic Force Microscope (AFM), Fourier Transmission Infrared spectrum (FTIR), and Energy Dispersive X-ray Spectroscopy (EDS) were used for coating characterization. Forty-eight blocks of glass-infiltrated aluminum oxide ceramic were fabricated. The ceramic surfaces were polished following sandblasting. Three groups of specimens (16 for each group) with different surface treatment were prepared. Group P: no treatment; group PO: treated with silane solution; group PTO: silica coating via sol-gel process, followed by silane application. Composite cylinders were luted with resin cement to the test specimens. Half of the specimens in each group were stored in distilled water for 24 h and the other half were stored in distilled water for 30 days before shear loading in a universal testing machine until failure. Selected ceramic surfaces were analyzed to identify the failure mode using a scanning electron microscopy (SEM). Nanostructured silica coatings were prepared on glass-infiltrated aluminum oxide ceramic surfaces by the sol-gel process. The silicon element on the ceramic surface increased significantly after the coating process. The mean shear bond strength values (standard deviation) before artificial aging were: group P: 1.882 +/- 0.156 MPa; group PO: 2.177 +/- 0.226 MPa; group PTO: 3.574 +/- 0.671 MPa. Statistically significant differences existed between group PTO and group P, and group PTO and groups PO. The failure mode for group P and group PO was adhesive, while group PTO was mixed. The mean shear bond strength values (standard deviation) after artificial aging were: group P: 1.594 +/- 0.111 MPa; group PO: 2.120 +/- 0.339 MPa; group PTO: 2.955 +/- 0.113 MPa. Statistically significant

  14. The Encapsulation of Organic Molecules and Enzymes in Sol-Gel Glasses: Novel Photoactive, Optical, Sensing and Bioactive Materials. A Review

    Science.gov (United States)

    1992-01-01

    al. (26) have been ahlc to demonstrate invertase activity in aggregates of whole yeast cells trapped in thin sol-gel films, whereas films with cell...the sol-gel proc,:ss, first in’:%ducci i-i 19F,4, opened the road for a whole new class of materials anJ to ja. :. activity in many laboratories. rhc...developed based on the doping idea, namely, chemically active sol-gel glasses Catalysts, sensors and the exciting group of bioactive materials, are some

  15. Short hybrid polymer/sol-gel silica waveguide switches with high in-device electro-optic coefficient based on photostable chromophore

    OpenAIRE

    Y. Enami; Luo, J.; A. K-Y. Jen

    2011-01-01

    The highest electro-optic (EO) coefficient to date is achieved in short polymeric directional coupler switches based on hybrid EO polymer/sol-gel silica waveguides. Optimized poling conditions in such waveguides give a highest in-device EO coefficient of 160 pm/V at 1550 nm using highly efficient and photostable guest–host EO polymer SEO100. Adiabatic waveguide transitions from the passive sol-gel core to active EO polymer cores surrounding the sol-gel core are shown using EO polymer cores wi...

  16. Improvement of glassy sol-gel sensors for preventive conservation of historical materials against acidity

    Directory of Open Access Journals (Sweden)

    Carmona, N.

    2007-08-01

    Full Text Available Sensors based on sol-gel glassy coatings doped with 2[4-(dimethyl-amino phenylazo] benzoic acid are able to change their optical absorption when they are submitted to different concentration of H3O+ and OH-. The sensors behaviour in field tests was studied in Cracow (Poland, varying the normal procedure of operation to improve their response. Both the sensors optical parameters and the environmental conditions (temperature, humidity, pressure, SO2 and NOx concentrations were measured. The sensors response was analysed in terms of their visible absorbance changes, which are due to local neutralisation reactions in the sensors surface by the join effect of acid pollutants and humidity. Correlations between the main acid pollutant (SO2 concentration and the sensors response are established to provide a relation between the optical absorption and the environmental pH. The sensors are able to detect and monitorise environmental acidity, as well as to alert on the pollutant concentration that may damage most of the historical materials.

    Los sensores a base de recubrimientos vítreos sol-gel dopados con ácido 2[4-(dimetil-amino fenilazo] benzoico son capaces de cambiar su absorción óptica cuando se someten a distintas concentraciones de iones H3O+ y OH-. La respuesta de los sensores en ensayos de campo se estudió en Cracovia (Polonia variando el procedimiento normal de uso, con el fin de mejorar su respuesta. Se midieron tanto los parámetros ópticos de los sensores como las condiciones ambientales (temperatura, humedad, presión y concentraciones de SO2 y de NOx. La respuesta de los sensores se analizó en términos de los cambios de su absorción visible. Dichos cambios se deben a reacciones locales de neutralización que tienen lugar en la superficie de los sensores, debido al efecto conjunto de los contaminantes de carácter ácido y a la humedad ambiental. Se establecieron correlaciones entre la concentración del contaminante

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-08

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

  18. 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}.

  19. Modulation of the silica sol-gel composition for the promotion of direct electron transfer to encapsulated cytochrome c.

    Science.gov (United States)

    Gamero-Quijano, Alonso; Huerta, Francisco; Morallón, Emilia; Montilla, Francisco

    2014-09-02

    The direct electron transfer between indium-tin oxide electrodes (ITO) and cytochrome c encapsulated in different sol-gel silica networks was studied. Cyt c@silica modified electrodes were synthesized by a two-step encapsulation method mixing a phosphate buffer solution with dissolved cytochrome c and a silica sol prepared by the alcohol-free sol-gel route. These modified electrodes were characterized by cyclic voltammetry, UV-vis spectroscopy, and in situ UV-vis spectroelectrochemistry. The electrochemical response of encapsulated protein is influenced by the terminal groups of the silica pores. Cyt c does not present electrochemical response in conventional silica (hydroxyl terminated) or phenyl terminated silica. Direct electron transfer to encapsulated cytochrome c and ITO electrodes only takes place when the protein is encapsulated in methyl modified silica networks.

  20. Sol gel chemistry applied to the synthesis of actinide-based compounds for the fabrication of advanced fuels

    Energy Technology Data Exchange (ETDEWEB)

    Robisson, A.C.; Lemonnier, S.; Grandjean, S

    2004-07-01

    The chemistry of the sol-gel process is based on hydroxylation and condensation of molecular precursors and can be used for the elaboration of advanced nuclear fuel or transmutation targets. On the one hand, some fundamental studies are conducted, based on complexation reactions to modulate and control the reactivity of the different cations (Zr(IV) and minor actinides) prior to hydrolysis and condensation step. The purpose of this work is to obtain hetero poly-condensation in order to form homogenous compounds with a controlled microstructure. On the other hand, internal gelation process, one of the important sol-gel routes for the preparation of actinides microspheres (the dedicated design for advanced nuclear fuel or transmutation targets) is developed. Investigations are currently carried out to study the gelation behaviour of solutions containing actinides (III) or (IV) in comparison with the more well known behaviour of U(VI) studied during the development of process for beads production (1960 - 1990). (authors)