Transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto silica glass substrates by the sol–gel method. The effect of different Sn doping on the crystallinity, structural, optical and electrical properties of ZnO:Sn thin films were investigated by XRD, SEM, UV-VIS spectrophotometer and four-point probe method respectively. Among all of ZnO:Sn thin films in this paper, Sn-doped with 2 at.% exhibited the best properties, the surface demonstrate an accumulative crystallization and hexagonal structure, with a high-preferential c-axis orientation, namely an average transmittance of 90% and the resistivity of 19.6 Ω·cm.
ZnO thin films with and without Ni-doping were successfully deposited by sol-gel method with zinc acetate dihydrate as inorganic precursor, and nickel (II) acetate tetrahydrate as dopant. The solutions were prepared by dissolving zinc acetate and nickel (II) acetate in ethanol and diethanolamine (DEA) as its chelating agent. Thin films were fabricated by using spin-coating method on glass substrates. ZnO films were obtained by pre-heating and post-heating at 300 °C for 10 minutes and 500 °C for 1 h respectively. The films were analyzed by X-ray diffraction (XRD), UV-Vis transmittance and photoluminescence (PL). All samples exhibit high transparency in visible. Ni dopant does not alter so much ZnO structure, which due to the ion substitution between Ni and Zn. However, the Ni tends to create a dopant energy interlayer in ZnO energy band gap which cause significant change in PL intensity.
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<p>Tubular halloysite clay mineral and nanocrystalline TiO<sub>2 </sub>were incorporated in the preparation of nanocomposite films on glass substrates via sol-gel method at 450ºC. The synthesis involves a simple chemical method employing nonionic surfactant molecule as pore directing agent along with the acetic acid-based sol-gel route without addition of water molecules. Drying and thermal treatment of composite films ensure elimination of organic material and lead to the formation of TiO<sub>2</sub> nanoparticles homogeneously distributed on the surface of the halloysite. Nanocomposite films without cracks of active anatase crystal phase and small crystallite size on halloysite nanotubes are characterized by microscopy techniques and porosimetry methods in order to examine their structural properties. The composite halloysite-TiO<sub>2 </sub>films with variable quantities of halloysite were examined as photocatalysts to the discoloration of Basic Blue 41 azo dye in water. These nanocomposite films proved to be very promising photocatalysts and highly effective to dye’s discoloration in spite of small amount of halloysite/TiO<sub>2</sub> catalyst immobilized onto glass substrates. It also has been shown that the efficiency of the halloysite/TiO<sub>2</sub> films could be further improved when silver particles were deposited on their surface after successful adsorption from an aqueous solution of a silver salt and UV reduction of the adsorbed ions.</p>
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In this work, nano-crystalline chromium oxide (Cr2O3) thin film was synthesized using the Sol-gel method. The thin film was deposited on a glass substrate at 50°C by using chromium nitrate, methanol, ethanol, polyvinyl alcohol with a magnetic stirrer device and a hot plate. Each deposited thin film annealed in the microwave oven at 200°C. The structure of the prepared thin film was examined by means of X-ray diffraction (XRD). The Shearer formula was used to calculate the size of the film granules. The scanning electron microscopy (SEM) was used to study the surface morphology. UV-VIS measurement was also carried out to study optical properties of a sample by recording transmittance and reflectance data in the range 341-800 nm wavelength. All the tests confirmed the existence of a thin layer of Cr2O3 on the glass substrates.
ABSTRUCTThe sol-gel method is one of the most appropriate technologies for the preparation of functional thin oxide coatings. However, few studies on the structure near the interface between sol-gel coatings and substrates have been reported. In this study, the structures of thin TiO2 gel coatings were investigated by XPS in order to elucidate the interaction between the coatings and the glass substrates. TiO2 gel coatings were prepared from Ti-alkoxide by hydrolysis and dip-coating on silica glass plates. Thickness and refractive index measurements were made by ellipsometry. Changes in Ols spectra for the coatings were observed at locations near the interface. Dynamic microhardness measurements for the coatings and the coated glasses were made. These results suggest the formation of a Ti-O-Si bond at the interface.
Nanocrystalline TiO2 and Halloysite clay mineral composite films prepared by sol-gel method: Synergistic effect and the case of silver modification to the photocatalytic degradation of Basic Blue- 41 azo dye in water.
