Showing papers on "Sol-gel published in 2010"
TL;DR: In this article, the main chemical routes used in the sol-gel synthesis of undoped ZnO thin films and highlights the chemical and physical parameters influencing their structural properties are summarized.
Abstract: During the last years, ZnO thin films have been studied extensively due to their potential applications in e.g. piezoelectric and optoelectronic devices or photovoltaic cells. Ordered c-axis orientation of ZnO crystallites is desirable for applications where crystallographic anisotropy is a prerequisite such as for short-wavelength semiconductor diode lasers (SDLs), and piezoelectric surface acoustic wave or acousto-optic devices. Many works were dedicated to c-axis oriented ZnO thin films elaboration and the study of their properties, including physical and chemical methods. For instance, sol–gel processes are particularly well adapted to produce ZnO films in a simple, low-cost and highly controlled way. This review summarizes the main chemical routes used in the sol–gel synthesis of undoped ZnO thin films and highlights the chemical and physical parameters influencing their structural properties. In this process, the ZnO films synthesis includes three principal steps: (i) solution preparation, (ii) coating and (iii) heat treatment. For the first step, the particle formation is discussed including nucleation and growth, particle size, morphology and colloids stability. These three steps involve several parameters such as: (i) nature and concentration of precursor, solvent and additive, and solution aging time, for the chemical system, (ii) coating method, thickness and substrate for the coating step, and (iii) pre-and post-heat treatment for the last step. The influence of these steps and synthesis parameters on ZnO thin films orientation is discussed.
618 citations
TL;DR: Thermogravimetric analysis shows that these silica microcapsules are degraded in two distinct steps, and have good thermal stability, and can achieve good phase-change performance, high encapsulation efficiency, and good antiosmosis property.
405 citations
190 citations
TL;DR: In this article, a simple dip coating method for the preparation of thermally stable, transparent super-hydrophobic silica films on glass substrates at room temperature by sol-gel process was demonstrated.
187 citations
TL;DR: In this article, the mesoporous self-aggregated nanoclusters of pure and transition metal (Mn, Co and Ni) doped ZnO have been synthesized by refluxing their acetate precursors in diethylene glycol (DEG) medium.
180 citations
TL;DR: In this article, a sol-gel process for the production of Na(2)O-containing bioactive glass ceramics, potentially enabling their use as medical implantation materials was reported.
160 citations
TL;DR: In this article, a spin-coated tungsten oxide nanostructured thin film was used for the fabrication of gas sensors and dye-sensitized solar cells, and it was shown that these materials can be rendered into anhydrous or partially or fully hydrated Tungsten oxides.
Abstract: Among the available metal oxide nanostructures, tungsten oxide has remained, at times, troublesome to fabricate, with many synthetic methods often requiring exotic equipment and or reagents. In this work, we present a systematic investigation demonstrating a new method for the deposition of anhydrous and hydrated nanostructured tungsten oxide thin films via spin coating. The attributes of these materials include the following: high surface area, controllable deposition, and compatibility with existing semiconductor fabrication infrastructure making this method a suitable candidate for application in the manufacture of gas sensors and dye sensitized solar cells. We will show that it is possible to form micrometer thick highly crystalline nanostructured thin films and, using Raman, SEM, XRD, XPS, and TEM analysis, will prove that these nanostructures can be rendered into anhydrous or partially or fully hydrated tungsten oxides. We further demonstrate the application of these materials in the fabrication of ...
160 citations
TL;DR: In this article, thin films of zinc oxide were deposited by spin coating method on different substrates and the obtained samples were thermally treated at temperatures from 400°C up to 850°C.
157 citations
TL;DR: In this article, a polyvinyl alcohol (PVA) assisted sol-gel method was used to prepare a carbon-coated Li3V2(PO4)3 cathode material.
144 citations
TL;DR: In this article, the effect of silica precursors on amorphous networks was examined by single-gas permeation and binary-component gas separation characteristics for hybrid silica membranes.
143 citations
TL;DR: In this article, the effect of aging time of ZnO sol on the structural and optical properties of the films was studied and it was shown that appropriate aging of the sol is very important for the improvement of structural and the optical quality of the thin films derived from sol-gel method.
27 May 2010
TL;DR: In this article, the authors investigated the influence of the heating rate of the preheating process (4 or 10°C/min) on the crystallization, surface morphology, and optical properties of sol-gel derived ZnO thin films.
TL;DR: In this article, the structural and optical properties of ZnO thin films prepared by sol-gel spin coating process were studied and the band gap and Urbach energy were calculated.
Abstract: In this work we have studied the structural and optical properties of ZnO thin films prepared by sol-gel spin coating process. Zinc acetate dihydrate was used as the precursor material. Thin films of ZnO were prepared on Quartz substrate post annealed at 400oC, 500oC and 600oC. X-ray diffraction (XRD) of the films showed polycrystalline nature. Scherrer’s formula was used to calculate crystallite size. Scanning electron microscopy (SEM) study showed granular surface. The refractive index, extinction coefficient and thickness of the films were measured with spectroscopic Ellipsometry. The band gap and Urbach energy were calculated. The photoluminescence measurement revealed UV emission at ~ 380 nm.
TL;DR: In this article, the sol gel method was employed to prepare peroxopolytungstic acid (P-PTA), and Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al2O3 substrates by spin coating method.
TL;DR: In this article, the electrical and optical properties of undoped zinc oxide (ZnO) and cadmium-doped ZnO (CZO) films deposited by a sol-gel method have been investigated.
TL;DR: In this article, superparamagnetic maghemite nanoparticles were applied to a stable suspension of citric acid-coated nanoparticles and the quality of the silica layer was characterized using electron microscopy and by performing leaching in HCl.
TL;DR: In this article, the effect of annealing temperature on the electrochromic behavior of NiO thin films was investigated using X-ray diffraction analysis (XRD), and the particle size was determined by Scherrer formula.
Abstract: Nickel oxide thin films were prepared by sol–gel dip coating process. Nickel acetate tetrahydrate [Ni(CH3COO)2·4H2O] has been used as the starting material with absolute ethyl alcohol to prepare NiO thin films on both glass and indium tin oxide glass (ITO) substrates with heat treatment at different annealing temperatures from 673 to 733 K. Thermogravimetric analysis (TGA) was studied for the xerogel sample. Polycrystalline structures of the prepared films were detected by X-ray diffraction analysis (XRD), and the particle size was determined by Scherrer formula. The morphology and the structure of the prepared thin films were investigated by the transmission electron microscope (TEM). The optical properties of NiO thin films were examined. The optical constants such as the absorption coefficient (α), extinction coefficient (k), the energy gap (Eg) and the refractive index (n) of the prepared films were determined. The effect of annealing temperature on the electrochromic behavior was observed providing that good electrochromic performance was T
TL;DR: In this article, the optical transmittance and reflectance spectra of TiO 2 thin films were analyzed for different annealing temperatures and the optical gap of the films were determined.
TL;DR: In this article, the authors proposed a mechanism of PDMS bridge formation based on sol viscosity, sol particle size changes, and FTIR identification, which is attributed to a "compulsive aggregation" process of the sol.
Abstract: Thick silica antireflective (AR) coatings with controlled thickness and durable AR performance were prepared by a base-catalyzed sol−gel process using tetraethyl orthosilicate (TEOS) as precursor and hydroxyl-terminated polydimethylsiloxane (PDMS) as a modifier. The addition of PDMS greatly increased the controllable viscosity range of the silica sol but did not obviously affect the particle size. This phenomenon is attributed to a “compulsive aggregation” process of the sol, which involves the formation of “PDMS bridges” between silica particles in the sol. The mechanism of “PDMS bridge” formation is proposed based on sol viscosity, sol particle size changes, and FTIR identification. The increased controllable viscosity range provided a convenient way to prepare AR coatings with controlled thickness and therefore with controlled wavelength of maximum transmittance. The introduction of PDMS into the silica sol also increased the hydrophobicity and hence the durability of the AR coatings in wet environments.
TL;DR: In this paper, the behavior/resistance of four optimised sol-gel coating systems (inorganic, hybrid organic-inorganic and containing zirconium ions and containing cerium ions) against corrosion of AZ91 magnesium alloy were studied.
TL;DR: In this article, the catalytic activity of SnO2 was investigated for the hydrogenation reaction of styrene using ethanol as the solvent at 70 C and 1 atmospheric pressure, and the product conversions in the presence of catalysts prepared at different conditions were between 37 to 72%.
Abstract: AsystematicstudyonthepreparationofSnO2nanoparticlesusingasimplesol-geltechniquehasbeen conductedbyvaryingreactionparameterssuchasconcentrationofammonia,ammoniafeedrateandreaction temperature. The tin oxide obtained was characterized by using FTIR, BET, XRD and TEM. Particles size was obtained in the range of 4 to 5.6 nmand the surface area was found to be between 76 to 114 m 2 g -1 depending on the reaction parameters. Meanwhile, the catalytic activity of SnO2 was first time investigated for the hydrogenation reaction of styrene using ethanol as the solvent at 70 C and 1 atmospheric pressure. It is found that SnO2 acts as a good catalyst in this hydrogenation process. The product conversions in the presence of catalysts prepared at different conditions were between 37 to 72%.
TL;DR: In this paper, the evolution of the structure and microstructure of the precursor gel, heated at various temperatures as well as, the piezoelectric and ferroelectric properties of BNT-BT0.08 ceramics were studied.
TL;DR: In this paper, the authors describe the room temperature synthesis of adherent and porous super-hydrophobic silica films on glass substrates using methyltriethoxysilane (MTES) as hydrophobic reagent by sol-gel process.
TL;DR: In this article, the effect of pH and the titanium precursor on the cluster and particle formation during titanium alkoxide based sol-gel processes was investigated using electrospray ionization mass spectrometry (ESI-MS) and dynamic light scattering (DLS).
Abstract: In this work the effect of pH and the titanium precursor on the cluster and particle formation during titanium alkoxide based sol–gel processes was investigated using electrospray ionization mass spectrometry (ESI-MS) and dynamic light scattering (DLS). The influence of pH and the titanium precursor on the particle size, morphology, crystallinity and chemical composition of the resulting particles were investigated using differentiel scanning calometry (DSC), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), BET-adsorption isotherms and high resolution transmission electron microscopy (HR-TEM). ESI-MS investigation of the titanium clusters present during the nucleation and growth period showed that the number of titanium atoms in the clusters varied dependent on the alkoxide used. Moreover, it was found that the titanium clusters formed using titanium tetraethoxide (TTE) were smaller than the clusters formed by titanium tetraisopropoxide (TTIP) and titanium tetrabutoxide (TTB) under similar conditions. pH was not found to influence the nature of the titanium clusters present in the sol–gel solution. HR-TEM investigation of the TiO2 particles prepared at pH 7 and 10 showed that the primary particle size of the particles was around 3 nm. However, it was found that these primary particles aggregated to form larger secondary particles in the size order of 300–500 nm range. At pH 3 the particles grew significantly during the drying process due to destabilization of the colloidal solution leading to the formation of a gel. The highest specific surface area was found for particles synthesized under neutral or alkaline conditions based on TTIP. XRD analysis of the TiO2 particles showed that the particles synthesized at 25 °C were amorphous. First after heating the samples to above 300 °C the formation of anatase were observed.
TL;DR: In this paper, the effect of thickness on physical and electrical properties of as deposited ZnO thin films has been studied by X-ray diffraction spectroscopy, field emission scanning electron microscopy and atomic force microscopy.
TL;DR: In this paper, different amounts of montmorillonite nanoparticles were added to a water-based silanes mixture in order to improve the barrier properties of the sol-gel coating.
TL;DR: In this article, the effect of Ce:Ti molar ratio on the crystallization behavior of nanostructured TiO 2 -CeO 2 thin films and powders was studied.
Abstract: Nanostructured TiO 2 –CeO 2 thin films and powders were prepared by a straightforward aqueous particulate sol–gel route. Titanium (IV) isopropoxide and cerium chloride were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. The effect of Ce:Ti molar ratio was studied on the crystallisation behaviour of the products. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders crystallised at the low temperature of 500 °C, containing anatase–TiO 2 , rutile–TiO 2 and cubic-CeO 2 phases, as well as Ti 8 O 15 , Ti 3 O 5 and Ce 11 O 20 depending on annealing temperature and Ce:Ti molar ratio. Furthermore, it was found that CeO 2 retarded the anatase to rutile transformation up to 700 °C. The activation energy of crystallite growth was calculated in the range 1.92–8.79 kJ/mol. Transmission electron microscope (TEM) image showed that one of the smallest crystallite sizes was obtained for TiO 2 –CeO 2 binary mixed oxide, being 3 nm at 500 °C. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had nanostructured morphology with the average grain size in the range 17–28 nm at 500 °C. Thin films produced under optimised conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response towards low concentrations of CO gas at low operating temperature of 200 °C, resulting in increased thermal stability of sensing films as well as a decrease in their power consumption. Furthermore, calibration curves revealed that TiO 2 –CeO 2 sensors follow the power law, S = A [gas] B (where S is sensor response, coefficients A and B are constants and [gas] is the gas concentration) for the two types of gases, and they have excellent capability for the detection of low gas concentrations.
TL;DR: In this article, it was found that the preferential growth of (100) reflection peak has taken place in the 450, 550 and 600 °C annealed films, and the resistivity of the 500 °C Annealed film is measured to be 5 × 10− 1 Ω cm.
TL;DR: In this article, the effect of the ratios of positively charged valences to hydroxyl groups of PVA (Mn+/−OH) on the formation of Bismuth ferrite powders was investigated.
Abstract: Bismuth ferrite (BiFeO3) powders were synthesized by a sol–gel process using polyvinyl alcohol (PVA) as a complexing agent. Thermogravimetric, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and field-emission scanning electron microscope techniques were used to characterize precursor and derived oxide powders. The effect of the ratios of positively charged valences to hydroxyl groups of PVA (Mn+/–OH) on the formation of BiFeO3 was investigated. XRD analysis showed that single-phase and well-crystallized BiFeO3 was obtained from the Mn+/–OH=2:1 precursor at a temperature as low as 400°C. For the precursor with Mn+/–OH=4:1, BiFeO3 formed only at the temperature of 600°C. With Mn+/–OH=1:1 and 1.5:1 precursor, pure BiFeO3 powder was not obtained. In present work, single-phase BiFeO3 can be formed at lower temperature and less organics are required; furthermore, the process is simple and easy to control.