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Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy
摘要： Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO2) and is doped with Gd3+ ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce3+ and Cu+. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd3+-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce3+ and Cu+ fibers with a Birks’ constant, kB, of (0.0162 ± 0.0003) cm/MeV in comparison to (0.0333 ± 0.0006) cm/MeV and (0.0352 ± 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting kB for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
关键词： Bragg peak,dosimetry,Gd3+-doped silica,optical fibers,quenching,sol-gel technique,proton therapy
更新于2025-09-16 10:30:52
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Influence of Calcination Temperature on the Performance of TiO<sub>2</sub> Films in Dye-Sensitized Solar Cells
摘要： In this work, the effects of calcination temperature on the photovoltaic performance of TiO2 films prepared with non-hydrolytic sol-gel method were reported. The optimal photovoltaic performance of DSCs was obtained by annealing TiO2 film at 550 °C. The short-circuit current (Jsc), open-circuit voltage, fill factor (FF) and energy conversion efficiency were 15.68 mA·cm-2, 0.71 V, 0.62 and 6.83%, respectively.
关键词： dye-sensitized solar cell,photoanode film,performance,calcination temperature,non-hydrolytic sol-gel titanium dioxide
更新于2025-09-16 10:30:52
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Optical Thin Films of Metal Oxides Produced by the Sol-Gel Method for Photovoltaic Applications
摘要： The use of thin films in optoelectronic and photovoltaic devices is aimed at improving the physical properties of the substrate material. The modification of the surface of the silicon substrate is thus one of the greatest challenges in research on photovoltaic materials, in order to achieve even greater efficiency or better adapt their properties depending on the application. The technologies of applying layers vary depending on the effect to be obtained and the material from which the layer is formed. In practice, the most common method is chemical vapor deposition and physical vapor deposition, and the most commonly applied optical materials are SiO2, TiO2 and Si3N4.This paper presents the results of investigations on morphology and optical properties of the prepared aluminium oxide thin films. Thin films were prepared with use of sol-gel spin coating method. Surface morphology studies were carried out using an atomic force microscope. To characterize the surface of the thin films, 3D images and histograms of the frequency of individual inequalities were made. In order to characterize the optical properties of Al2O3 thin films, the reflectance and light transmission tests were performed using a spectrophotometer. Optical constants were determined using a spectroscopic ellipsometer. Results and their analysis show that the sol-gel method allows the deposition of homogenous thin films of Al2O3 with the desired geometric characteristics and good optical properties. Uniform, continuous thin layers with a roughness not exceeding a few nanometres were deposited. Their deposition enabled to reduce the reflection of light from the polished substrate below 15% in a wide range (425-800nm) while maintaining high transparencies (over 90%). The obtained results causes that mentioned thin films are good potential material for optics, optoelectronics and photovoltaics.
关键词： metal oxide,thin films,sol-gel
更新于2025-09-16 10:30:52
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Synthesis of Na-, Fe-, and Co-promoted TiO$_{2}$/multiwalled carbon nanotube composites and their use as a photocatalyst
摘要： The use of multiwalled carbon nanotubes (CNTs) in sol-gel synthesized titanium dioxide (TiO 2) photocatalysts as templates was systematically studied. CNTs have high oxidative thermal stability and the controlled removal of CNTs can be achieved at lower temperatures under air (cid:13)ow by the use of Na, Fe, and Co as a catalyst. These catalysts helped to reduce the oxidation temperature of CNTs; thus anatase phase was achieved without signi(cid:12)cant sintering. The use of a promoter, heat treatment, and various heat treatment atmospheres was e?ective in speci(cid:12)c surface area, crystallinity, and photocatalytic activity against methylene blue (MB) degradation. While the speci(cid:12)c surface area of bare TiO 2 was 22 m 2 /g, after templating surface areas as high as 191 m 2 /g were obtained. For the photocatalytic characterization, with bare TiO 2 , the rate constant for MB decomposition was 0.81 h (cid:0)1 , and for CNT{TiO 2 it was 1.31 h (cid:0)1 . Moreover, after Na promotion, the rate constant increased to 1.85 h (cid:0)1 . The results showed that CNTs can be used as a template to tailor and improve the textural properties. Moreover, as a novel material, the Na promotion in CNT{TiO 2 samples showed the best photocatalytic activity by enhancing the interaction between TiO 2 and CNT surfaces.
关键词： anatase,Carbon nanotubes,TiO 2,doping,sol-gel,template,photocatalysis,composite
更新于2025-09-16 10:30:52
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Controlled sol–gel synthesis of oxygen sensing CdO?:?ZnO hexagonal particles for different annealing temperatures
摘要： CdO : ZnO hexagonal particles were synthesized by a sol–gel precipitation method at di?erent annealing temperatures. A mixed crystal phase of cubic and wurtzite structures was observed from X-ray di?raction patterns. The micrographs showed hexagonal shapes of the CdO : ZnO nanocomposites particles. The energy dispersive X-ray spectroscopy mapping images showed a uniform distribution of the Cd and Zn. The CdO : ZnO nanocomposite pallet annealed at 550 (cid:1)C has an electrical resistance of 0.366 kU at room temperature. The nanocomposites showed an excellent sensing response against oxygen gas with a sensing response of 47% at 200 (cid:1)C for the CdO : ZnO particles annealed at 550 (cid:1)C. The sensor response and recovery times were found to be 43s and 45s, respectively. The sensor response was due to the sorption of oxygen ions on the surfaces of the CdO : ZnO hexagonal particles.
关键词： sol–gel,annealing temperature,hexagonal particles,oxygen sensing,CdO : ZnO
更新于2025-09-16 10:30:52
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SYNTHESIS AND CHARACTERIZATION OF La-DOPED ZnO (La:ZnO) FILMS FOR PHOTODETECTORS
摘要： In this work, the La-doped ZnO thin films were fabricated with different La concentrations by the use of sol–gel technique to synthesize the photodevice. The transparent metal oxide La-doped ZnO thin films were grown on glass and p-Si substrates using spin coating technique. Optical, surface morphology and electrical characterization of the fabricated Al/p-Si/La:ZnO/Al devices have been performed using I–V and C/G–V characteristics under dark and different illumination conditions. Herein, from I–V characteristics, the crucial electronic parameters such as barrier height, ideality factor and series resistance were investigated. The photodevice transient photocurrent increases with the increase of illumination intensity. The current ratios of Ion/Ioff were calculated for the fabricated devices. Among the devices, the highest photoresponse was found to be about 2186 for the Al/p-Si/La(0.5 wt.%):ZnO/Al structure. The Rs–V behavior of fabricated device confirms the presence of interface states. The obtained results and photoresponse behaviors suggested that Al/p-Si/La:ZnO/Al devices can enhance the applications in optoelectronic devices such as photodetectors.
关键词： sol–gel,photoresponse,photodetector,doped ZnO,Electrical characteristics
更新于2025-09-16 10:30:52
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Investigation of the structural, optical, elastic and electrical properties of spinel LiZn <sub/>2</sub> Fe <sub/>3</sub> O <sub/>8</sub> nanoparticles annealed at two distinct temperatures
摘要： Nanoparticles of Li0.5ZnFe1.5O4 (LiZn2Fe3O8) with the spinel structure were prepared by a sol–gel auto-combustion method at two different annealing temperatures. X-ray diffractograms and Rietveld refinement confirmed the formation of the spinel structure. The morphology was analyzed by electron microscopy, which showed that the grains were composed of different crystallites. Elastic properties were determined from infrared spectroscopy. It was found that the elastic parameters increased with the increase in annealing temperatures. The band gap depends on the annealing temperature and it decreased on increasing the particle size. The conductivity of the specimen annealed at 500 °C followed either the Jonscher's model or Drude's model depending on the temperature range. This conductivity decreased when the annealing temperature was raised by 600 °C. AC conductivity was found to be controlled by the hopping model. A single relaxation phenomenon was evidenced for each sample from impedance analysis. The Nyquist diagram proved that the samples were simultaneously capacitive and resistive and also supported the presence of multiple relaxation times.
关键词： annealing temperature,spinel,conductivity,LiZn2Fe3O8,impedance analysis,band gap,elastic properties,sol–gel auto-combustion
更新于2025-09-16 10:30:52
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PEGylation of protein-imprinted nanocomposites sandwiching CdTe quantum dots with enhanced fluorescence sensing selectivity
摘要： Fluorescent sensors combining the selective recognition of protein molecularly imprinted polymers (MIPs) and the fluorescent sensing of quantum dots (QDs) have been studied considerably, but their fluorescence sensing selectivity for the target proteins remains to be increased. Herein, we propose a strategy for increasing the sensing selectivity by post-imprinting PEGylation of surface protein-imprinted nanocomposites with embedded QDs. With bovine hemoglobin (BHb) as a model protein template, protein MIP nanolayers were anchored over the CdTe QD decorated SiO2 nanoparticles by the sol–gel process using aminopropyltriethoxy silane and tetraethoxysilicane. PEG chains were then grafted onto the surface of the imprinted nanostructures via the nucleophilic reaction of the surface amine groups with N-hydroxysuccinimide ester-terminal methoxy-PEG, followed by template removal. The resultant PEGylated sensors showed significantly improved aqueous dispersion stability compared with the non-PEGylated controls. More importantly, such PEGylation greatly increased the fluorescence response selectivity, with the Stern–Volmer equation based imprinting factor increasing from 2.7 to 5.4. The PEGylated sensors were applied to determine BHb in bovine serum samples with satisfactory recoveries at three spiking levels ranging from 94.3 to 103.7%, indicating their potential application in real samples.
关键词： PEGylation,Fluorescent sensors,Protein molecularly imprinted polymers,Quantum dots,Stern–Volmer equation,Bovine serum samples,Sol–gel process,Bovine hemoglobin
更新于2025-09-16 10:30:52
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Optimization of parameters of integrated optical waveguides based on thin-film Sol-gel structures by using mathematical modelling
摘要： An algorithm for calculating optical waveguide film parameters was proposed, the use of which makes it possible to reduce the time for processing experimental data. The developed algorithm was tested using experimental data of waveguides samples with a wave-guiding layer of zirconium dioxide sol-gel films. A comparison of the developed algorithm and the Wolfram Mathematica program showed a good agreement of the results, as well as the developed method advantage in terms of using ease and timesaving spent on processing the results.
关键词： mathematical modelling,temperature optical coefficient,sol-gel technology,optical waveguide,integrated optics
更新于2025-09-16 10:30:52
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Pyrocatechol violet sensitized Ho-TiO <sub/>2</sub> /ZnO nanostructured material: as photoanode for dye sensitized solar cells
摘要： In this work TiO2, Holmium doped (Ho-TiO2) Titanium oxide nanoparticles (NPs) and the corresponding nanostructured combinations (Ho-TiO2/ZnO NC) were successfully synthesized through sol gel method and re?ux techniques respectively. The prepared nano materials were characterized with the help of x-ray diffraction Analysis (XRD), UV–visible spectroscopy, Scanning Electron Microscopy (SEM), Energy dispersive x-ray Analysis (EDX) and Fourier Transform infrared spectroscopy (FT-IR). The absorption spectra of nano materials were used for band gaps calculation. The band gap of pure TiO2 NPs was found to be 3.10 eV which was effectively tuned to 2.65 eV by the doping of Holmium at different concentrations. XRD patterns con?rmed the crystalline nature and purity of the synthesized nano materials. Morphology and elemental composition of the material were investigated using SEM and EDX respectively. FTIR helped in detecting the functional groups and grafting of the dye on the surface of nanoparticles. The nano materials were used as Photo-anodes in dye sensitized solar cells (DSSC). Pyrocatechol Violet dye was used as a photo-sensitizer. P3HT (polymer), a hole conducting polymer, was employed as a solid state electrolyte. I–V measurements were used for characterization of fabricated solar cells. Ho-TiO2/ZnO nanomaterial photosensitized with Pyrocatechol violet dye gave the highest percentage ef?ciency of 1.51. Other characteristic parameters of the fabricated devices such as short circuit current (Jsc), open circuit voltage (Voc), maximum power point (Mpp) and ?ll factor were found to be 11.2 mA cm?2, 0.41 V, 1.55(mW cm?2) and 0.33 respectively.
关键词： I–V curve,?ll factor,dye sensitized solar cell,sol gel method,SEM,pyrocatechol violet
更新于2025-09-16 10:30:52