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Sol-Gel Derived Dip Coated ZnO – La <sub/>2</sub> O <sub/>3</sub> Thin Film Transistors
摘要： ZnO thin ?lms are fabricated utilizing a cost effective sol-gel dip coating technique and potentially applied as active material in thin ?lm transistors (TFT). The channel length of the TFT is maintained at 40 μm. Thermally deposited high –k La2O3 is used as dielectric material. The fabricated ZnO ?lms are annealed in oxygen atmosphere at 500?C for 1 hour and characterized by XRD, EDX and SEM analysis. The TFTs are fabricated in top gate coplanar electrodes structure on glass substrates. The electrical characteristics of the TFTs are investigated and some important electrical parameters are evaluated. The TFTs exhibit ?eld effect mobility of 1.9 cm2/VS, low threshold voltage of 2.5 Volt, high ON/OFF current ratio of 107, sub-threshold swing of 0.8V/decade, transconductace of 1.2 × 10?3 mho and gain band-width product of 20 kHz.
关键词： ZnO,sol-gel dip coating,thin film transistors,electrical characteristics,La2O3
更新于2025-09-11 14:15:04
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Preparation and Photocatalytic Properties of Sr2-xAxFeMoO6 (X = 0, 0.1; A = Li, Na, K)
摘要： In this paper, the sol-gel method is used to synthesize a series of double perovskite oxides Sr2FeMoO6 and Sr1.9A0.1FeMoO6 (A = Li, Na, K). The crystal structure was investigated by X-ray powder diffraction. The results show that all the as-synthesized samples have tetragonal crystal structure, small amount of substitution has little effect to the structure of Sr2FeMoO6 and they can keep double perovskite structure. Their photocatalytic activities were evaluated by degradation of dye acid black 10 B. The effects of the dosage of photocatalyst, irradiation time, irradiation source, initial concentration of dye solutions and alkali metal ions doping on the photocatalytic activity of samples were investigated. The results show that all the samples present high photocatalytic activities. In the dye concentration range of 20-150 mg/L, the decolorizing rate of acid black 10 B can reach above 95 % when the dosage of photocatalyst Sr2FeMoO6 is 100 mg under UV irradiation for 40 min. Moreover, the photocatalytic activity of Li-doped sample is lower than that of the un-doped sample, but the photocatalytic activity of the Na- or K-doped samples are much better than the un-doped sample and the decolorizing rate is nearly 100 %.
关键词： Photocatalytic performance,Sr2FeMoO6,Alkali metal doping,Sol-gel method,Decolorizing rate
更新于2025-09-11 14:15:04
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Effect of Annealing on Optical Properties of Zinc Oxide Thin Films Prepared by Homemade Spin Coater
摘要： Zinc oxide (ZnO) thin films were deposited on the ordinary glass substrates by spin coating method. The precursor solution was prepared by mixing zinc acetate dihydrate in appropriate proportions with ethanol and diethanolamine (DEA). The obtained thin films were dried at 200oC for 15 minutes in hot air oven. Crystalline ZnO thin films were achieved following annealing process at temperatures 300o, 400o and 500oC for 2 hours. Thin films as- prepared were studied by X-ray diffraction and UV-visible spectroscopy. The films were transparent from near ultraviolet to infrared region. Optical band gap energy of ZnO was obtained 3.22 eV at 300oC. On annealing at 400o and 500oC, band gap energy was shifted at 3.14 eV and 3.05 eV respectively.
关键词： annealing,absorption spectra,sol-gel method,zinc oxide,band gap energy
更新于2025-09-11 14:15:04
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Fabrication of Luminescent Antireflective Coatings with CaMoO4:Eu3+/Ag Composite Structure
摘要： Highly transparent and luminescent CaMoO4:Eu3+/Ag composite films were fabricated on glass substrates as multifunctional antireflective (AR) coatings. The films were deposited through a combination of a sol–gel dip-coating technique and a hot water treatment. With the addition of an aluminum source in coating solutions, the sol–gel-derived films underwent a remarkable microstructural change during the hot water treatment due to the reaction between an amorphous alumina phase and water. This change brought both an antireflective effect (suppression of Fresnel reflection) and luminescence enhancement (suppression of total internal reflection) to the films. The introduction of Ag nanoparticles into the films further increased luminescence intensity without losing the antireflective effect.
关键词： calcium molybdate,silver nanoparticles,antireflective coatings,europium,nanocomposite,sol–gel method,photoluminescence
更新于2025-09-11 14:12:44
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Synthesis of Mesoporous TiO2/Boron-Doped Diamond Photocatalyst and Its Photocatalytic Activity under Deep UV Light (λ = 222 nm) Irradiation
摘要： There is a need for highly efficient photocatalysts, particularly for water purification. In this study, we fabricated a mesoporous TiO2 thin film on a boron-doped diamond (BDD) layer by a surfactant-assisted sol-gel method, in which self-assembled amphiphilic surfactant micelles were used as an organic template. Scanning electron microscopy revealed uniform mesopores, approximately 20 nm in diameter, that were hexagonally packed in the TiO2 thin film. Wide-angle X-ray diffraction and Raman spectroscopy clarified that the framework crystallized in the anatase phase. Current–voltage (I–V) measurements showed rectification features at the TiO2/BDD heterojunction, confirming that a p–n hetero-interface formed. The as-synthesized mesoporous TiO2/BDD worked well as a photocatalyst, even with a small volume of TiO2 (15 mm × 15 mm × c.a. 1.5 μm in thickness). The use of deep UV light (λ = 222 nm) as a light source was necessary to enhance photocatalytic activity, due to photo-excitation occurring in both BDD and TiO2.
关键词： photocatalyst,water purification,thin film,surfactant-assisted sol-gel method,p-n heterojunction,deep UV light,mesoporous metal oxide
更新于2025-09-10 09:29:36
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Studies on structural, optical and magnetic properties of (Ru, Mn) codoped ZnO nanostructures
摘要： Ruthenium and manganese codoped ZnO (RuxMn0.01Zn0.99-xO; x = 0.01, 0.02 and 0.03) were synthesized by sol-gel method via ultrasonication. The effects of codoping on structural, microstructural, optical and magnetic properties of the as-synthesized materials were characterized through X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and SQUID magnetometer, respectively. From the XRD pattern, it is evident that all the diffraction peaks can be indexed to the hexagonal wurtzite structure and shows the incorporation of dopants ie. Ru and Mn are substituted in the ZnO lattice. Nanosphere like morphology was observed in HRTEM analysis and the average particle sizes are found to be 20-30 nm, which are good agreement with the XRD crystallite size by Scherrer formula. Photoluminescence (PL) studies were carried out to investigate the optical properties of the as-synthesized materials and the defects related strong green emission peaks was observed in the TM codoped ZnO samples. It can be clearly seen from SQUID results, the loop is linear with the field indicating the presence of paramagnetism / anti ferromagnetism in the samples.
关键词： ZnO,sol-gel,optical properties,codoping,ultrasonication,magnetic properties,structural properties
更新于2025-09-10 09:29:36
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The Effect of Process Parameters on the Amorphous Citrate Sol-gel Synthesis of Cu-doped Ca12Al14O33
摘要： Ca12Al14O33 (C12A7) is a highly functional material due to its ability to act as an anionic source and its conversion from a wide band-gap insulator to a conductive oxide material as a function of processing. Cationic doping, on the order of 1 mol%, of C12A7 has been shown to have profound effects on the physical properties of the material. One such cation, Cu, increases the catalytic efficiency and drastically alters the electronic landscape. The amorphous citrate sol-gel synthesis technique is widely used to synthesize doped C12A7 materials as it promises homogeneous cationic dispersion and a fine and controlled grain size. This promise relies on the formation of a homogeneous citrate resin of cationic citrate species, homogeneous decomposition of cation citrate species, and homogeneous crystallization of the desired phase. In this report, theoretical complex diagrams are calculated to determine the optimal pH for citrate resin formation in the Cu-C12A7 system. The resin decomposition and crystallization kinetics are characterized through high-temperature X-ray diffraction and thermogravimetric analysis. The optimal pH range for the citrate resin homogeneity was theoretically determined to be a range from 3 to 6, and experimental characterization shows that raising the pH from <1 to 4 leads to Cu-C12A7 phase purity, reduces grain size by 30%, and inhibits CaCO3 formation to lower the synthesis temperature from ~900 °C to 840 °C. This report highlights the importance of sol-gel solution chemistry and the corroboration of XRD analysis with microstructural analysis.
关键词： C12A7,Citrate sol-gel synthesis,Doped synthesis,Ca12Al14O33,In-situ X-ray Diffraciton
更新于2025-09-10 09:29:36
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White-Light Emitting Di-Ureasil Hybrids
摘要： White-light emitting materials have emerged as important components for solid state lighting devices with high potential for the replacement of conventional light sources. Herein, amine-functionalized organic-inorganic di-ureasil hybrids consisting of a siliceous skeleton and oligopolyether chains codoped with lanthanide-based complexes, with Eu3+ and Tb3+ ions and 4,4'-oxybis(benzoic acid) and 1,10-phenanthroline ligands, and the coumarin 1 dye were synthesized by in situ sol–gel method. The resulting luminescent di-ureasils show red, green, and blue colors originated from the Eu3+, Tb3+, and C1 emissions, respectively. The emission colors can be modulated either by variation of the relative concentration between the emitting centers or by changing the excitation wavelength. White light emission is achieved under UV excitation with absolute quantum yields of 0.148 ± 0.015, 0.167 ± 0.017, and 0.202 ± 0.020 at 350, 332, and 305 nm excitation, respectively. The emission mechanism was investigated by photoluminescence and UV–visible absorption spectroscopy, revealing an efficient energy transfer from the organic ligands to the Ln3+ ions and the organic dye, whereas negligible interaction between the dopants is discerned. The obtained luminescent di-ureasils have potential for optoelectronic applications, such as in white-light emitting diodes.
关键词： lanthanide complexes,di-ureasil organic–inorganic hybrids,in situ sol–gel synthesis,white light emission,coumarin 1
更新于2025-09-10 09:29:36
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Studies of the characteristic and reaction mechanism of silica xerogel by sol–gel method catalyzed by alkylbiguanide as a strong organic base
摘要： Treatment of tetraethyl orthosilicate with 1,2-diisopropyl-4,4,5,5-tetra-methyl biguanide (A) as a highly strong base immediately gave silica gel by means of hydrolysis and condensation reaction at room temperature. The resulting wet gel was transparent and showed high density after dryness. From the results of gas adsorption and BET analysis, silica gel obtained by the treatment of strong base A had larger specific surface area and pore volume than silica gel that was prepared by a regular or less strong base such as tetramethylammonium hydroxide (TMAH). FTIR analysis revealed that the peak strength of Si-OH bond at 960 cm?1 of silica gel prepared by highly strong base A was smaller than that of TMAH. To understand the mechanism behind such difference, a mixture of diphenylsilandiol and dimethoxydiphenylsilane were reacted with highly strong base A, and the resulting products comprised linear-chain siloxane oligomer and octaphenylcyclotetrasiloxane. Our results indicate that silanol generated by hydrolysis of TEOS is activated by A and the activated silanol undergoes subsequent direct reaction with unhydrolyzed alkoxy silane to give condensation products in ethanol. Such a direct polycondensation between silanol and alkoxy silane brought by highly strong base A led to three-dimensional crosslinking having a higher bulk density of silica gel.
关键词： Biguanide,Silica xerogel,Sol–gel processes,Strong organic base
更新于2025-09-10 09:29:36
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Sol-gel synthesis and characterization of ZnAl2O4 powders for transparent ceramics
摘要： The sol-gel synthesis of ZnAl2O4 ceramic powders from alkoxide and acetate sources of metals, as well as the microstucture and the hardness of the hot-pressed ZnAl2O4 specimens were considered. ZnAl2O4 powders were prepared by the hydrolysis of an alcohol solution of aluminium isopropoxide using an aqueous solution of zinc acetate followed by heat treatment. The thermal evolution of the ZnAl2O4 precursor was investigated. The effect of calcination temperature on the morphology and the specific surface area of ZnAl2O4 powders were also studied. The sintering of the resultant powders to the high transparent ceramic using a hot pressing with 1 wt% ZnF2, as a sintering additive was successfully demonstrated. The in-line transmittance of ZnAl2O4 ceramics (1 mm thickness) achieved 80% in the visible region and 85 % at 5 μm; Vickers hardness was 11.6 GPa.
关键词： transparent ceramic,powders,sol-gel synthesis,ZnAl2O4
更新于2025-09-10 09:29:36