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Upconversion Properties of BaY2(MoO4)4:Er3+/Yb3+ Green Phosphors Synthesized via Cyclic Microwave-Modified Sol-Gel Route
摘要： The double molybdate BaY2(MoO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (Er3+ = 0.05, 0.1, 0.2 and Yb3+ = 0.2, 0.45) have been successfully synthesized by a cyclic microwave-modified sol-gel process and their upconversion properties have been investigated. Well-crystallized particles were formed after heat treatment at 900 °C for 12 h, showing a fine and homogeneous morphology. Under excitation at 980 nm, BaY2(MoO4)4:Er3+/Yb3+ particles exhibited a strong 525 nm emission band and a weak 550 nm emission band in the green region and a very weak 655 nm emission band in the red region. The Raman spectra of the particles indicated the strong peaks at higher frequencies and weak peaks at lower frequencies.
关键词： Raman Spectroscopy,Upconversion properties,Green phosphors,Microwave-modified sol-gel
更新于2025-09-04 15:30:14
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Photocatalytic activity of gadolinium doped TiO <sub/>2</sub> particles for decreasing heavy metal chromium (VI) concentration
摘要： Titanium dioxide (TiO2) is among the most potential photocatalyst. However, TiO2 only works under UV light due to the relatively wide band gap energy. To overcome this, TiO2 is infiltrated (doped) by rare earth elements such as gadolinium (Gd). TiO2 was synthesized using sol gel method, while Gd/TiO2 photocatalyst was synthesized by the mixing methods of sol-gel and impregnation. The crystals are then characterized using XRD and SEM-EDX. The XRD diffractogram demonstrated that the crystallinity synthesized of TiO2 had an anatase structure similar to the structure of anatase P-25 as references. The SEM-EDX showed that Gd ion could not enter the crystal lattice, but only dispersed on the surface of TiO2 particles. The optimum result of decreased Cr(VI) concentration was reported using Gd/TiO2 1% w/w by a decrease of up to 94%, after irradiated with ultraviolet for one hour.
关键词： sol-gel method,gadolinium doping,TiO2,Cr(VI) concentration,photocatalyst
更新于2025-09-04 15:30:14
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Structural and optoelectronic properties of Ce-Al2O3 nanoparticles prepared by sol-gel precursors
摘要： Pure and Ce-doped Al2O3 nanoparticles (NPs) were synthesized in different cerium percentages of 1%, 2%, and 3% by cerium chloride and aluminum nitrate precursors in the presence of powerful reducing agent-NaBH4 and CTAB stabilizers using sol-gel method. To examine the crystal, morphological, optical, and electronic properties, the XRD, FESEM, TEM, FTIR, UV-DRS, and PL analyses were used for the heated samples in 1000 °C for 4 hours. The XRD analysis indicated that the pure sample has γ, δ and θ phases, and the structure remained unchanged when Ce impurity was increased. The EDS analysis showed that the percentage of Al element was 47.40 wt% in the pure sample and that it increased to 53.83 wt% for 1% doped sample increasing Al ions in tetrahedral and octahedral sites of alumina through increasing Ce impurities. The TEM results revealed the sphere-like particles with mean particle size of 26 nm in diameter at a 3% level of impurity. The FTIR result showed that an increase in AlO4 adsorption peak in 821 cm-1 compared to AlO6 adsorption peak in 619 cm-1 was due to the dominance of vibrating bonds of tetrahedral sites rather than octahedral sites in alumina. The optical UV-DRS analysis also demonstrated the redshift configuration in a sample by increasing Ce dopant and reducing energy bandgap from 4.10 to 3.26 eV for pure and 3% Ce-doped Al2O3 NPs, respectively. Finally, the photoluminescence (PL) results indicated that increasing Ce dopant reduced electron-hole recombination leading to an increase in photocatalytic activity.
关键词： Chemical Synthesis,Cerium dopant,Sol-gel,Ceramics,Al2O3 NPs
更新于2025-09-04 15:30:14
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CuO photoelectrodes synthesized by the sol–gel method for water splitting
摘要： CuO is an attractive photocatalytic material for water splitting due to its high earth abundance and low cost. In this paper, we report the deposition of CuO thin films by sol–gel dip-coating process. Sol deposition has attractive advantages including low-cost solution processing and uniform film formation over large areas with a fairly good control of the film stoichiometry and thickness. Pure CuO phase was obtained for calcination temperatures higher than 360 °C in air. The CuO photocurrents for hydrogen evolution depend on the crystallinity and the microstructure of the film. Values of ?0.94 mA cm?2 at pH = 8 and 0 V vs. RHE were achieved for CuO photoelectrodes annealed at 400 °C under air. More interestingly, the stability of the photoelectrode was enhanced upon the sol–gel deposition of a TiO2 protective layer. In this all sol–gel CuO/TiO2 photocathode, a photocurrent of ?0.5 mA cm?2 is achieved at pH = 7 and 0 V vs. RHE with a stability of ~100% over 600 s.
关键词： TiO2 protecting layer for CuO photoelectrode,Sol–gel,CuO photoelectrode,Water splitting
更新于2025-09-04 15:30:14
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Improved Hydrophobicity of Polydimethylsiloxane (PDMS) Coating with ZnO Nanostructures
摘要： In this present work, an environmentally safe hydrophobic cotton surface comprising of PDMS and different morphology of Zinc oxide (ZnO) nanostructures via simple dip coating method was developed. ZnO nanosphere and ZnO nanoflakes were synthesized via sol gel method while ZnO nanorods were synthesized via solution precipitation method. The precursors used to prepared ZnO nanospheres, nanoflakes and nanorods are zinc acetate dehydrate, zinc chloride and zinc nitrate tetrahydrate respectively. ZnO nanostructures were analysed using FESEM and XRD. The hydrophobic cotton surface was characterized via FT-IR and WCA analysis. A WCA of 144.15° was achieved when coating the cotton with ZnO nanoflakes (ZnO-NF:PDMS).
关键词： ZnO nanostructures,Polydimethylsiloxane,Solution precipitation method,Hydrophobicity,Sol gel method,Dip coating
更新于2025-09-04 15:30:14
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Strain-Mediated Substrate Effect on the Dielectric and Ferroelectric Response of Potassium Sodium Niobate Thin Films
摘要： If piezoelectric thin films sensors based on K0.5Na0.5NbO3 (KNN) are to achieve commercialization, it is critical to optimize the film performance using low-cost scalable processing and substrates. Here, sol–gel derived KNN thin films are deposited using a solution with 5% of potassium excess on Pt/TiO2/SiO2/Si and Pt/SrTiO3 substrates, and rapid thermal annealed at 750 ?C for 5 min. Despite an identical film morphology and thickness of ~335 nm, an in-plane stress/strain state is found to be tensile for KNN films on Pt/TiO2/SiO2/Si, and compressive for those on Pt/SrTiO3 substrates, being related to thermal expansion mismatch between the substrate and the film. Correspondingly, KNN films under in-plane compressive stress possess superior dielectric permittivity and polarization in the parallel-plate-capacitor geometry.
关键词： stress/strain,ferroelectric hysteresis,dielectric properties,KNN thin films,sol–gel,thermal expansion
更新于2025-09-04 15:30:14
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Ferroelectromagnetic Properties of PbFe1/2Nb1/2O3 (PFN) Material Synthesized by Chemical-Wet Technology
摘要： In this work, PbFe1/2Nb1/2O3 (PFN) ceramic samples synthesized by chemically wet method (precipitation from the solution) were obtained. Due to the tendency to form powder agglomerates, the synthesized powder was subjected to ultrasound. The sintering was carried out under various technological conditions, mainly through controlling the sintering temperature. -X-ray powder-diffraction (XRD), scanning electron microscope (SEM) microstructure analysis, as well as the examinations of dielectric, ferroelectric, and magnetic properties of the PFN ceramics were carried out. Studies have shown that hard ceramic agglomerates can be partially minimized by ultrasound. Due to this treatment, closed porosity decreases, and the ceramic samples have a higher density. Optimization and improvement of the technological process of the PFN material extends the possibility of its use for the preparation of multiferroic composites or multicomponent solid solutions based on PFN. Such materials with functional properties ?nd applications in microelectronic applications, e.g., in systems integrating ferroelectric and magnetic properties in one device. The optimal synthesis conditions of PFN ceramics were determined to be 1050 ?C/2 h.
关键词： perovskite type materials,ferroelectromagnetics,chemical-wet technology,sol-gel,multifereroics
更新于2025-09-04 15:30:14
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Ferroelectric properties of Ag doped PbZr0.53Ti0.47O3 thin film deposited by sol–gel process
摘要： To suppress the generation of oxygen vacancy during the PbZr0.53Ti0.47O3 (PZT) film synthesis process, herein, the 0–3 type Ag/PZT film is chosen as a prototype to systematically investigate the mechanisms of oxygen vacancy decrease and the relationship of ferroelectric properties. The uniform and dense films were successfully fabricated on fluorine tin oxide glasses (FTO) by facile sol–gel processes. It is confirmed the existence of silver nanoparticles in the film, indicating the composite ferroelectric films are of 0–3 type. When Ag doping mole concentration is 0.010 in the sol, a large remnant polarization (Pr) of ~ 50.7 μΧ/cm2 is got, which is 37.9 μΧ/cm2 for pure PZT. UV–vis spectrum confirms the generation of Ag2O in the process of mixing the sol. Furthermore, the oxygen vacancies caused by natural evaporation of lead specie are effectively reduced because of the decomposition of Ag2O, confirmed by X-ray photoelectron spectroscopy. This work points out the generated Ag2O as the intermediate product is the key to achieve high remnant polarization in Ag/PZT based film and make it as a promising candidate for memory applications.
关键词： remnant polarization,oxygen vacancy,Ag doped PbZr0.53Ti0.47O3,sol–gel process,Ferroelectric properties
更新于2025-09-04 15:30:14
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Electro-photocatalytic Fenton Decolorization of Orange G Using Mesoporous TiO2/stainless Steel Mesh Photo-Electrode Prepared by the Sol-Gel Dip-Coating Method
摘要： A photo-electrochemical process is a powerful and eco-friendly method for treating industrial wastewater. Electro-photocatalytic Fenton (EPF) was employed for orange G decolorization using two kinds of photo-electrodes with TiO2 film-coated stainless steel (SS) mesh. These photo-electrodes are prepared by a dip-coating method from the sol-gel-derived TiO2 sols incorporating with various amounts of P25+TiO2 powders (SGDC method). The single dip-coated electrode with the TiO2 sol containing 50 g/L P25 powders possesses similar crystallinity and decolorization performance to the four repetitive dip-coated electrodes with pure TiO2 sol. The kinetics of orange G decolorization using P25+TiO2 film electrode in photocatalytic (PC), electro-Fenton (EF) and EPF processes followed pseudo first-order kinetics model, and the EPF has the highest reaction rate. The efficiency of orange G decolorization achieves 78% via the EPF reaction for 3 h. The SGDC method using the TiO2 sol containing P25 powders not only enhances the TiO2 coating on the SS substrate, but also produces microcracks in the film, that facilitates the in-situ generation of ferrous ions and further induces the EPF reaction for an effective degradation of organic matter in wastewater.
关键词： mesoporous film,P25 TiO2,Sol-gel dip-coating (SGDC),electro-photocatalytic Fenton (EPF)
更新于2025-09-04 15:30:14
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Hydrogen Sensing Properties of Co-Doped ZnO Nanoparticles
摘要： In this study, the gas sensing properties of Co-doped ZnO nanoparticles (Co-ZnO NPs) synthesized via a simple sol-gel method are reported. The microstructure and morphology of the synthesized Co-ZnO NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Co-ZnO NPs were then used for developing a conductometric gas sensor for the detection, at mild temperature, of low concentration of hydrogen (H2) in air. To evaluate the selectivity of the sensor, the sensing behavior toward some VOCs such as ethanol and acetone, which represent the most important interferents for breath hydrogen analysis, was also investigated in detail. Results reported demonstrated better selectivity toward hydrogen of the Co-ZnO NPs sensor when compared to pure ZnO. The main factors contributing to this behavior, i.e., the transition from n-type behavior of pristine ZnO to p-type behavior upon Co-doping, the modification of oxygen vacancies and acid-base characteristics have been considered. Hence, this study highlights the importance of Co doping of ZnO to realize a high performance breath hydrogen sensor.
关键词： Co-doped ZnO,gas sensor,sol-gel,nanoparticle,sensing mechanism,hydrogen,ethanol
更新于2025-09-04 15:30:14