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The preparation and luminescent characters of mesoporouss SiO2/Sm composite materials
摘要： During the mesoporous SiO2 preparation process, Sm3+ ions are dissolved in the anhydrous ethanol solution. The ethanol solution permeates the mesoporous SiO2 then the gel is formed by sol-gel synthesis method. Such, the Sm3+ ions are absolutely introduced into the porous of the mesoporous SiO2 when the gel is dried. In this study, the mesoporous SiO2/Sm3+ composite materials were synthesized by the sol-gel synthesis method. A series of characterization means were used to evaluate the structures of the materials. The near infrared spectrum was used to evaluate the luminescent characteristics. The excitation and emission spectrum of prepared materials showed that the materials had better near infrared luminescent characteristics.
关键词： character,luminescent,rare earth,SiO2 aerogel,sol-gel method
更新于2025-09-19 17:15:36
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Sol-gel Syntheses of Photocatalysts for the Removal of Pharmaceutical Products in Water
摘要： A screening study on seven photocatalysts was performed to identify the best candidate for pharmaceutical products degradation in water. Photocatalysts were deposited as thin films through a sol-gel process and subsequent dip-coating on glass slides. The efficiency of each photocatalyst was assessed through the degradation of methylene blue first, and then, through the degradation of 15 different pharmaceutical products. Two main types of synthesis methods were considered: aqueous syntheses, where the reaction takes place in water, and organic syntheses, where reactions take place in an organic solvent and only a stoichiometric amount of water is added to the reaction medium. Photocatalysts synthesized via aqueous sol-gel routes showed relatively lower degradation efficiencies; however, the organic route required a calcination step at high temperature to form the photoactive crystalline phase, while the aqueous route did not. The best performances for the degradation of pharmaceuticals arose when Evonik P25 and silver nanoparticles were added to TiO2, which was synthesized using an organic solvent. In the case of methylene blue degradation, TiO2 modified with Evonik P25 and TiO2 doped with MnO2 nanoparticles were the two best candidates.
关键词： sol-gel process,thin films,pharmaceutical products,TiO2,photocatalysis
更新于2025-09-19 17:15:36
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Advanced thin gas barriers film incorporating alternating structure of PEALD-based Al2O3/organic-inorganic nanohybrid layers
摘要： In this work, we reported excellent plasma-enhanced atomic layer deposition (PEALD)-based Al2O3/organic-inorganic (O-I) nanohybrid gas barrier film which exhibits ultralow water vapor transmission rate (WVTR), high activation energy for permeation, high optical transmission in visible light and sufficient flexibility. The values of WVTR and activation energy for permeation of our PEALD-based Al2O3/O-I nanohybrid 4 pair gas barrier film are obtained to be 7.83 × 10?5 g/m2/day (60 °C, 90% RH) and 103.10 kJ/mol via the electrical calcium test. Optical transmission in visible light is 96.14% and critical bending radius 7 mm–9 mm. Introduction of O-I nanohybrid layers between PEALD-based Al2O3 layers improved the properties of gas barrier films on anticorrosion, adhesion, and flexibility.
关键词： Anticorrosion,Encapsulation,Plasma enhanced atomic layer deposition (PEALD),Sol-gel,Nanoparticles,Organic-inorganic nanohybrid,Al2O3
更新于2025-09-19 17:15:36
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Optimized properties of innovative ElectroChromic Device using ITO / Ag / ITO electrodes
摘要： The "Dielectric/Metal/Dielectric" (DMD) stacked films being used as transparent and conductive (TC) electrodes, have demonstrated excellent application in the ElectroChromic (EC) process and devices. In this work, multilayers (IAI) made of 50 nm of Indium Tin Oxide (ITO) / 5 nm of metallic silver (Ag) / 30 nm of ITO that exhibit band-gap, low resistance of 7.4 ? and the high figure of merit of 9.9×10-3 ?-1 were introduced in a complete five-layer Glass / IAI / NiOx / LiClO4-PC-PMMA / WO3 / IAI / Glass ElectroChromic Device (ECD). The single IAI electrode as well as the two actives EC layers Glass / IAI / NiOx and Glass / IAI / WO3 were firstly characterized for their TC and EC properties respectively. Then, the EC properties of the complete five-layer ECD were analyzed. Fast response time (2.02 s for the bleaching and 2.25 s for complete coloration), wide optical modulation in the visible light region (~55% at 550 nm), long lifetime (more than 6000 s), large capacity and good stability as well as high coloration efficiency (31.7 cm2 C–1) were obtained. The improved EC performance of ECD were related to the good electrical and optical properties of IAI electrode.
关键词： Electrochromic characteristics,Electrochromic devices,Multilayer,Polymer gel electrolyte,Transparent conductive materials
更新于2025-09-19 17:15:36
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The effect of imprint on remanent piezoelectric properties and ferroelectric aging of PbZr <sub/>0.52</sub> Ti <sub/>0.48</sub> O <sub/>3</sub> thin films
摘要： Ferroelectric films suffer from both aging and degradation under high ac-field drive conditions due to loss of polarization with time. In this study, the roles of defect chemistry and internal electric fields on the long-term stability of the properties of piezoelectric films were explored. For this purpose, lead zirconate titanate (PZT) films with a Zr/Ti ratio of 52/48 doped with Mn- (PMZT) or Nb- (PNZT) were deposited on Pt coated Si substrates by the sol-gel method. It was demonstrated that the magnitude of the internal field is much higher in PMZT films compared to PNZT films after poling in the temperature range of 25-200°C under an electric field of -240 kV/cm. The development of the internal field is thermally activated, with activation energies from 0.5±0.06 to 0.8±0.1 eV in Mn doped films and from 0.8±0.1 to 1.2±0.2 eV in Nb doped films. The different activation energies for imprint suggests that the physical mechanism underlying the evolution of the internal field in PMZT and PNZT films differs; the enhanced internal field upon poling is attributed to (1) alignment of oxygen vacancy – acceptor ion defect dipoles (((Mn''_Ti - V_O^{??})_x, (Mn'_Ti - V_O^{??})') in PMZT films, and (2) thermionic injection of electron charges and charge trapping in PNZT films. In either case, the internal field reduces back switching, enhances the remanent piezoelectric properties, and dramatically improves the aging behavior. PMZT films exhibited the greatest enhancement, with reduced high temperature (180°C) aging rates of 2-3%/decade due to improved stability of the poled state. In contrast, PNZT films showed significantly larger high temperature aging rates (15.5%/decade) in the piezoelectric coefficient, demonstrating that the fully poled state was not retained with time.
关键词： aging,PZT,sol-gel,thin film,donor,acceptor,imprint
更新于2025-09-19 17:15:36
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Fluorolytic Sol–Gel Synthesis of Nanometal Fluorides: Accessing New Materials for Optical Applications
摘要： The potential of fluorolytic sol–gel synthesis for a wide variety of applications in the field of optical materials is reviewed. Based on the fluorolytic sol–gel synthesis of nanometal fluorides, sols of complex fluorometalates have become available that exhibit superior optical properties over known classical binary metal fluorides as, for instance, magnesium fluoride, calcium fluoride, or strontium fluoride, respectively. The synthesis of transparent sols of magnesium fluoroaluminates of the general composition MgxAlFy, and fluoroperovskites, [K1?xNax]MgF3, is reported. Antireflective coatings fabricated from MgF2, CaF2, MgxAlFy, and [K1?xNax]MgF3 sols and their relevant properties are comprehensively described. Especially the heavier alkaline earth metal fluorides and the fluorperovskites crystallizing in a cubic crystal structure are excellent hosts for rare earth (RE) metals. Thus, the second chapter reflects the synthesis approach and the properties of luminescent systems based on RE-doped alkaline earth metal fluorides and [K1?xNax]MgF3 phases.
关键词： nanometal fluorides,antireflective coatings,sol–gel synthesis,luminescent materials
更新于2025-09-19 17:15:36
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Preparing CdS QDs in sodium alginate gel: realizing water-solubility and stimuli-responsiveness of QDs in an integrative way
摘要： Quantum dots (QDs) were of great interest due to the excellent fluorescence property and have been widely studied. Comparing with the typical organometallic synthetic routes and hydrothermal method that were usually carried out under high temperature, colloidal template could be used for preparing QDs in mild conditions and have gained increasing attention. In this prospect, hydrogel was an ideal colloidal template for preparation of QDs in aqueous medium while the related study for in-situ preparation of QDs in gel and the consequent functionalization of QDs was in demand. In this paper, we proposed a two-step method to prepare CdS QDs in sodium alginate (SA) gel which showed effective constraint in uniform size distribution of QDs. Without extra ligands introduction, the prepared CdS-SA QDs showed responsiveness to pH and detectability to Fe3+ which provide a simplified way for functionalization of QDs. The CdS-SA QDs showed good biocompatibility and stability in a certain concentration which indicated the application prospect of the CdS-SA QDs in fields of biological labeling and environmental sensor.
关键词： gel,stimuli responsiveness,pH,Sodium alginate,CdS QDs
更新于2025-09-19 17:15:36
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A New Dealcoholization Method in the Synthesis of Vinyl Methyl Phenyl Silicone Resins for LED Encapsulation
摘要： The oligosiloxane resins were synthesized through hydrolytic sol-gel reaction and remained many hydroxyl groups, which did great harm to the curing process and resulted in poor performance of the cured products. In previous works, epoxy-modified silicone resins were synthesized by dealcoholization, a reaction between 3-glycidoxypropylmethyldimethoxysilane and terminal hydroxyl groups in phenyl silicone resins. Although this method eliminated the hydroxyl groups, it caused a large loss of vinyl groups inevitably and a poor stability of cured products. In this study, methyltrimethoxysilane (MTMS) was used to eliminate hydroxyl groups containing in vinyl methyl phenyl silicone resins, which were synthesized through hydrolytic sol-gel reaction. Most of residual hydroxyl groups were deleted effectively and the great loss of vinyl groups were avoided in the dealcoholization reaction. Then, the methyl phenyl silicone materials were fabricated by hydrosilylation reaction between the synthesized vinyl methyl phenyl silicone resins and hydrogen-containing ones. The cured silicone materials showed excellent optical performance (~ 89.1% at 450 nm) and good adhesion performance. In addition, due to less vinyl loss in the vinyl methyl phenyl silicone resins, the cured methyl phenyl silicone materials exhibited higher cross-linking density, better thermal resistance (5% mass loss at 435 °C) and better mechanical properties (50 shore D) compared with the epoxy-modified phenyl silicone materials. The lumen depreciation (working 168 h at 50 mA) and reflow soldering tests further demonstrated the methyl phenyl silicone materials possessed good thermal stability. These results indicated that the methyl phenyl silicone materials could be used as a LED encapsulant with a good performance.
关键词： LED packaging,Methyltrimethoxysilane,Non-hydrolytic sol-gel,Hydrolytic sol-gel,Vinyl methyl phenyl silicone resin
更新于2025-09-19 17:13:59
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Spectroscopic investigation of red Eu3+ doped ceria nanophosphors and promising color rendition for warm white LEDs
摘要： Europium-ion doped CeO2 phosphors with different Eu3+ concentrations were synthesized via sol-gel combustion synthesis. X-ray diffraction patterns revealed the formation of pure cubic structure of CeO2 even after the incorporation of 35 mol% Eu3+. The excitation spectra of CeO2:Eu3+ displayed a broad band (330- 370 nm) and several sharp peaks (393- 532 nm) owing to the charge transfer (CT) from O2- to Ce4+ ions and f-f transitions of Eu3+ ions respectively. The evaluation of CT band was explained on the basis of environmental factors. The phosphors were illuminated with blue light and showed the characteristic red luminescence corresponding to the 5D0→ 7FJ transitions of Eu3+ as confirmed from XPS. The emission was observed to increase with the increase in the Eu3+ concentration upto 35 mol% without any quenching. Judd-Ofelt parameters were evaluated using the emission spectroscopy to explain the variation in ligand environment and enhancement of red color purity to 80%. The thermal stability of present phosphors was measured by estimating activation energy and TG-DSC analysis. Robust blue-excitation and sharp red-emission with high color-purity and promising thermal stability in fabricated WLEDs indicated the suitability of CeO2:Eu3+ phosphors for white light emitting diodes with quantum yield efficiency up to 84.6%.
关键词： color purity,sol-gel assisted combustion,photoluminescence,WLED,charge transfer
更新于2025-09-19 17:13:59
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Na incorporation controlled single phase kesterite Cu2ZnSnS4 solar cell material
摘要： It is theoretically and experimentally challenging to fabricate single phase Cu2ZnSnS4 (CZTS) and more difficult to synthesize it by sol-gel method. Theoretical work reveals that Na can passivate the dangling bonds in the grain boundaries of CZTS and thus enhance the photovoltaic performance. Therefore, Na incorporation may be an effective way in passivating defects in CZTS films and fabricating CZTS with high quality and single phase. In this study, we will try to incorporate Na into CZTS films by sol-gel method to help passivate defects in CZTS and achieve single phase kesterite CZTS films using a different solvent 2-methoxybutanol. Different Na/(Cu+Zn+Sn) atomic ratios (0%-3%) will be employed. Through controlling Na incorporation amount in solution, we can prevent the generation of other phases like SnO2 and a pure single phase kesterite CZTS can be achieved. The optical band gap of the optimal CZTS film is 1.24 eV. All Na doped CZTS films show p-type conduction behavior.
关键词： Solar energy materials,Sol-gel preparation,Crystal structure
更新于2025-09-19 17:13:59