Sol–gel synthesis and characterisation of ZnO-based nanosystems (original) (raw)
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Sol–gel synthesis of ZnO–SiO2 thin films: impact of ZnO contents on its photonic efficiency
Journal of Sol-Gel Science and Technology, 2014
Highly crystalline ZnO-SiO 2 films obtained by a sol-gel method at different ZnO contents were deposited on silicon substrate (P(100)) using spin coating process. The XRD results revealed that the strong ZnO(100) peak is grown with highly c-axis oriented film and the crystallinity is progressively improved with increasing ZnO contents. SEM micrographs of the films deposited on silicon substrate show a homogeneous and uniformity structure at different ZnO content. The prepared ZnO-SiO 2 films are compared with either a film prepared from a commercial photocatalysts Hombikat UV-100 or Pilkington Glass Activ TM by the determination of their photonic efficiencies for degradation of methylene blue. The photocatalytic efficiency of the 10 wt% ZnO-SiO 2 film was found to be about four times higher than film prepared from UV-100 or Pilkington Glass Activ TM. The photocatalytic efficiencies of ZnO-SiO 2 films are increased with increasing ZnO content from 1 wt% to 10 wt% ZnO and then decreased at 15 wt% ZnO. The order of photocatalytic efficiencies of ZnO-SiO 2 films at different ZnO content and commercial photocatalysts after 6 h illumination were as following: 10 wt% ZnO [ 15 wt% ZnO [ 1 wt% ZnO [ as-prepared 10 wt% ZnO-SiO 2 film [ UV-100 [ Pilkington Glass Activ TM , which suggested that the ZnO-SiO 2 films are photoactive than commercial photocatalysts. The improved efficiency and potentially the lowcost synthesis suggest that this material might be practically useful as a photocatalyst film.
Formation of ZnO in or on glasses by using the Sol-Gel and chemical bath deposition techniques
… on Circuits and …, 2010
In the first part of this work was produced Zinc Oxide (ZnO) into a glass matrix by using the Sol-Gel Technique at room temperature, these materials were prepared using tetraethyl orthosilicate (TEOS) as precursor, the Zn ions were added before the jellification step trough an aqueous solution of zinc acetate. These glasses were characterized by X-ray diffraction, optic absorption, FT-IR and Raman spectroscopy. The X-ray patterns showed amorphousness. The optical absorption shows a shoulder in the UV range corresponding whit ZnO confined to the vitreous matrix. The spectra by FT-IR show characteristic vibrations of Si-O-Si with interaction Zn +2 . Raman scattering let us to identify and precise the formation of the ZnO. In the second part of this work was immersed glass substrates into an aqueous chemical bath with external controlled temperature, the chemical solutions contained in the bath were a Zn Ions source (ZnSO 4 ) 0.1 M, a pH 10 Buffer solution (NH 4 Cl/NH 4 OH), Ethanolamine to complex the Zn ions, and pure water, resulting ZnO films hexagonally structured with energy band gap of 3.3 eV, growing 1000 nm during 25 minutes followed of 60 minutes to 75°C and 85°C in the same chemical reaction.
On the Optical and Structural Propeties of ZnO Thin Films Synthesized by a Sol-Gel Technique
Zinc oxide (ZnO) films were prepared by an alternative route to the sol-gel process and their structural and optic properties carefully investigated. The deposition of the films was carried out on glass substrates by using a dip-coating technique. Zinc acetate dihydrate was used as inorganic precursor. This compound was first dissolved in ethanol and nitric acid. The obtained solution was then mixed with a citric acid and ethylenglycol, which were previously dissolved. XRD pattern con-firmed the hexagonal wurtzite structure of the synthesized material. Optical transmittance spectra showed absorption band at 3.3 eV. Scanning Electron Microscope (SEM) analysis showed excellent morphology of the samples with very flat sur-faces. Películas delgadas de ZnO fueron preparadas por una ruta alternativa a la técnica convencional de sol-gel. Las propiedades estructurales y ópticas de dichas muestras fueron cuidadosamente estudiadas. La deposición de las películas fue llevada a cabo sobre sustr...
Characterisation, analysis and optical properties of nanostructure ZnO using the sol–gel method
Micro & Nano Letters, 2012
Nanostructure ZnO was grown on thin aluminium layer, deposited on silicon substrate using the sol-gel method. The surface morphologies of nanostructure ZnO at different precursor concentrations were studied using scanning electron microscopy. Raman spectroscopy suggested that nanorods started to grow along with nanoflakes at a precursor concentration of 50 mM and the density of the nanorods significantly increases when the concentration was raised to 75 mM. Raman spectra were intensified and red shifted with the increment of precursor concentration. Optical properties of refractive index and optical dielectric constant are investigated. The structural defects at lower level of precursor were probably due to the hypoxic environment, whereas the red shift of Raman spectra was due to the structural change of ZnO nanocrystals.
Sol-gel synthesis of ZnO thin films
Thin Solid Films, 1996
TransparEnt and crackfree thin films of ZnO have been deposited on fused silica, soda glass, silicon wafers and KBr single crystals using the sol-gel technique. A sol has been prepared by reacting zinc acetate and ethylene glycol and dissolving the resultant transparent brittle solid in dry n-propanol. A proton accepter like triethyl amine was added to assist hydrolysis of zinc acetate. The resulting solution was readily gelled on addition of water. Films were spin east on polished substmtes, gelled in humid air and pyrolysed at 450 °C to get polyerystalline ZnO thin films. The films were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-Vis absorption spectroscopy.
Journal of Physics and Chemistry of Solids, 2013
ZnO-SiO 2 nanocomposite consisting of ZnO nanostructures grown in SiO 2 (silica) host matrix was obtained via hydrolysing Tetraethylorthosilicate (TEOS) with ethanolic solution of Zinc nitrate hexahydrate using Sol-gel method. Systematic study of the key parameters (precursor, concentration, and heat treatment conditions) has been taken into account that influences the growth mechanism and morphology of the as formed nanostructures. X-ray diffraction (XRD) analysis was used to determine the crystallinity, particle size and lattice parameter. Scanning electron microscopy (SEM) of the sample reveals the formation of ZnO nanostructures in silica matrix. Room temperature Photoluminescence (PL) measurement of the sample was done to understand the nature of possible defect level transition responsible for visible and rarely observed orange-red emissions in ZnO. This study reveals the usefulness of the nanocomposites as a luminescent material.
The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol-Gel Process
Nanomaterials (Basel, Switzerland), 2017
Hybrid nanomaterials based on zinc oxide were synthesized via the sol-gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. Th...
Studies on sol-gel dip-coated nanostructured ZnO thin films
Journal of Nanostructures, 2019
Nanostructured ZnO thin films were prepared by sol-gel dip coating technique. Zinc acetate and ammonium hydroxide were used as precursors and ethanol was as solvent. Ammonium hydroxide (NH4OH) solution was added drop-wise under vigorous stirring to obtain the sol-gel of different pH (varying from 6.9 to 7.2). ZnO thin films were obtained by dipping the glass substrates for few seconds and then dried in air at room temperature. This process was repeated for different number of coats for the typical sol. Different numbers of coating cycle was employed to obtain the films with varying thicknesses. These films were annealed at 5000C and were characterized by x-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analysis of x-rays (EDAX). ZnO thin films obtained from sol-gel dip-coating technique were observed to nanostructured. Average particle size was observed to be smaller than 50 nm. The most of the particles were observed to be spherical in shape....
Effect of different technological approaches on the optical properties of ZnO sol-gel thin films
Journal of Physics: Conference Series, 2014
The work presents a sol-gel approach with two types of solvents for ZnO films deposition in view of varying the films' structural and optical properties. The ZnO films were characterized by X-Ray diffraction (XRD) and found to have a polycrystalline wurtzite phase structure. The grain sizes and the lattice parameters were determined; it was established that the ZnO crystallites' size increases with the annealing temperatures from 25 nm to 36 nm. The ZnO films possess high transmittance in the visible spectral range. Further, the optical band gap values were estimated. The material's vibration properties were analyzed by Fourier Transform Infrared (FTIR) spectroscopy. The two technological sol-gel approaches for deposition of ZnO films, using two different solvents, proved to be successful in producing structures with different structural and optical properties. The thin films fabricated were very smooth and uniform and exhibited a high transparency in the visible spectral range.
Optical properties of ZnO thin films prepared by sol–gel process
Microelectronics Journal, 2009
Abstract： Nanosized ZnO films were prepared by sol-gel process on quartz substrates. The effects of sol concentration and annealing temperature on the surface morphology, microstructure and optical properties of the films were investigated. The results show that the sols remain stable and usable for spin-coating within 7 d. The ZnO films have a homogeneous and dense surface with grain size about 30 nm. The ZnO thin film annealed at 500 ℃ for 1 h from the sol with Zn concentration of 0.8 mol/L shows an average transmittance of 94% in visible wavelength range. The optical band gaps in ZnO films by various annealing temperatures are from 3.265 eV to 3.293 eV. The violet emission located at 438 nm is probably due to the recombination transitions relating to the interface traps at the grain boundaries.