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Green Synthesis Approach for Nano sized CoFe2O4 through Aloe Vera Mediated Sol-gel Auto Combustion Method for High Frequency Devices
摘要： Nanosized CoFe2O4 was synthesized by Aloe vera-mediated sol-gel auto-combustion method. The yielded nanoparticles were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) to investigate the phase formation and morphology of the obtained powders. FTIR, XRD and Raman spectra revealed the formation of single phase CoFe2O4. FESEM micrographs showed the formation of some bud like structure and the particle size obtained is around 50-65?nm. Investigation of magnetic properties viz. saturation magnetization (Ms), remenant magnetization (Mr) and coercivity (Hc) were studied from the M-H loop and were found to be 72.23 emu/gm, 31.29 emu/gm, 1519 Oe respectively. In addition, the massive dielectric constant, low dielectric loss, and AC conductivity of the CoFe2O4 nanoparticles were dependent on the frequency (100 Hz-1 MHz), method of preparation and grain size. Room temperature ferroelectric measurement reveals a partially unsaturated P-E loop due to the high coercive field and influence of leakage current.
关键词： Aloe vera plant extract,magnetism,nanostructured materials,Dielectric properties,sol-gel auto combustion
更新于2025-09-23 15:21:21
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Fabrication and performance of Lu2O3:Eu3+ nanowire arrays with different nanowire diameters
摘要： Lu2O3:Eu3+ nanowire arrays with different nanowire diameters were successfully fabricated by sol-gel process using submicron porous anodic aluminum oxide (AAO) templates. The nanowires in each array are homogeneous and highly ordered, and have uniform diameter defined by the template. They exhibit polycrystalline with Lu2O3 cubic structure. The crystallite sizes of the Lu2O3:Eu3+ nanowires increase with the increase of the pore diameters of AAO templates and are less than that of nanopowder prepared in the same conditions due to the confinement of AAO template on the coalescence of Lu2O3:Eu3+ nanocrystallites. The Lu2O3:Eu3+ nanowire arrays within AAO templates exhibit good performances of photoluminescence and X-ray excited optical luminescence. The emission peaks can be ascribed to 5D0→7FJ transitions of Eu3+ (J = 0, 1, 2, 3). The luminescent intensities of the Lu2O3:Eu3+ nanowire arrays also enhance with the increase of the pore diameters of AAO templates. This phenomenon is not only due to the increase of the filling ratio of Lu2O3:Eu3+, but also relates to the improvement of crystallinity. The latter mechanism is further confirmed by the fluorescent decay times of Eu3+ emission in the nanowires with different diameters. It is believed that the Lu2O3:Eu3+ nanowire array can become a promising high-spatial-resolution scintillation screen used in X-ray imaging.
关键词： Lu2O3:Eu3+ nanowire array,Diameter and crystallinity,Luminescence,AAO template and sol-gel method
更新于2025-09-23 15:21:21
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Observation of Optical Band-Gap Narrowing and Enhanced Magnetic Moment in Co-Doped Sol–Gel-Derived Anatase TiO <sub/>2</sub> Nanocrystals
摘要： The magnetic behavior of TiO2 and doped TiO2 nanocrystals has been a challenge due to the unambiguous nature of defects present in oxide semiconductors. Here, a simple, low-temperature sol?gel method is developed for the synthesis of low-dimensional and highly efficient stable anatase TiO2 nanocrystals. The X-ray powder diffraction pattern and Raman spectra confirm the formation of a single-phase anatase structure of TiO2. High-resolution transmission electron microscopy studies reveal the crystalline nature of the sol?gel-derived nanocrystals. The increase in lattice parameters together with the shifting and broadening of the most intense Eg(1) mode in micro-Raman spectra of Co-doped TiO2 nanocrystals indicate the incorporation of Co in TiO2. Shifting of the absorption edge to the visible region in UV?visible spectra indicates narrowing of the band gap due to Co incorporation in TiO2. X-ray photoelectron spectra confirm the presence of Co2+ and Co3+ in Co-doped TiO2 samples. Oxygen vacancy defects lead to the formation of bound magnetic polarons which induces a weak ferromagnetic behavior in air-annealed 3% Co-doped TiO2 at room temperature. It is observed that irrespective of the dopant ion, whether magnetic or nonmagnetic, the overlapping of bound magnetic polarons alone can induce ferromagnetism, while the magnetic impurities give rise to an enhanced paramagnetic moment for higher Co concentrations. A detailed understanding on the variation of these magnetic properties by estimating the concentration of bound magnetic polarons is presented, which is in corroboration with the photoluminescence studies. The observed band-gap narrowing in Co-doped TiO2 nanostructures and the mechanism underlying the magnetic interactions associated with the magnetic impurity concentration are advantageous from an applied perspective, especially in the field of spintronic and magneto-optic devices.
关键词： spintronic,magnetic moment,nanocrystals,optical band-gap narrowing,TiO2,magneto-optic devices,Co-doped,sol?gel
更新于2025-09-23 15:21:21
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Preparation of ultra-broadband antireflective coatings for amplifier blast shields by a sol–gel method
摘要： A type of λ/4–λ/4 ultra-broadband antire?ective coating has been developed using modi?ed low refractive silica and high refractive silica layers by a sol–gel dip coating method for ampli?er blast shields of the Shen Guang II high power laser facility (SG-II facility). Deposition of the ?rst layer (high refractive index silica) involves baking at 200 ?C in the post-treatment step. The second layer (low refractive index, n = 1.20) uses low refractive index silica sol modi?ed by acid catalysis. Thermal baking at temperatures no less than 500 ?C for 60 min offers chemical stability, ethanol scratch resistance, and resistance to washing with water. The average residual re?ection of dual-side-coated fused silica glass was less than 1% in the spectral range from 450 to 950 nm. Transmission gain has been evaluated by taking into account angular light, and the results show that the transmission gain increases with increasing light incidence. Even at 60?, the transmission spectrum of the broadband antire?ective coating effectively covered the main absorption peak of Nd:glass.
关键词： blast shields,ampli?er,ultra-broadband,sol–gel,antire?ective coating
更新于2025-09-23 15:21:21
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Effect of PbS quantum dot-doped polysulfide nanofiber gel polymer electrolyte on efficiency enhancement in CdS quantum dot-sensitized TiO2 solar cells
摘要： Quantum dot-sensitized solar cells (QDSSCs) are among the most promising low cost third generation solar cells. Semiconductor quantum dots have unique properties such as high molar extinction coefficients, tunable energy gap by the quantum confinement effect and the ability of multiple exciton generation. In this study, stable CdS QDSSCs were fabricated by using polysulfide liquid electrolytes and also by using cellulose acetate nanofiber-based gel electrolytes. Incorporation of PbS Q dots to the liquid or gel electrolyte showed a significant enhancement in solar cell efficiency. Under the simulated light of 100 mW cm-1 the efficiency of the polysulfide liquid electrolyte based CdS QD solar cells increased from 1.19% to 1.51% and the efficiency of the nanofibre gel electrolyte based CdS QD solar cells increased from 0.94 % to 1.46% due to the incorporation of 5% (wt/wt) PbS Q dots into the respective electrolytes. The efficiency increase has been attributed to the increase in short circuit photocurrent density due to increased sulfide ion (S2-) conductivity evidently caused by indirect ionic dissociation facilitated by PbS QDs.
关键词： Sulfide ion conductivity,Nanofibre gel electrolyte,Efficiency enhancement,Quantum dot sensitized solar cells,Quantum dot doped electrolyte
更新于2025-09-23 15:21:01
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Zinc oxide quantum dots for textile dyes and real industrial wastewater treatment: Solar photocatalytic activity, photoluminescence properties and recycling process
摘要： Three samples of ZnO quantum dots (ZQDs) were synthesized by a modified sol–gel method at different temperatures for 3 h. The first sample (S1) was prepared at room temperature 27 °C, while second and third samples (S2) and (S3) were prepared by the calcination process at 500 and 900 °C, respectively. A study of XRD and TEM determines the purity, high crystallinity and the presence of elongated shape of the prepared catalysts. On using TEM, DRS and EBT analysis, the crystallite size values, bandgap energy, and active surface area were (7.1 nm, 3.49 eV, and 150.1 m2/g), (9.8 nm, 3.45 eV and 112.2 m2/g) and (13.5 nm, 3.39 eV and 78.94 m2/g) for S1, S2, and S3, respectively. The Photoluminescence properties showed that the fluorescence rate for S1 was doubled the observed one in the S2 sample. The photodegradation results of both methyl orange as an industrial raw material and real industrial wastewater of S1 sample showed the finest activity when compared with the rest samples. It was cleared from the collecting data that the photocatalytic performance decreases with the crystallite size increases The mineralization efficiency of the real industrial wastewater that exposed to sunlight for six months were evaluated according to the allowed COD limit for Egyptian Environmental Law, In addition the recycling process for reusable for ZnO prepared samples for 8 times investigated and evaluated.
关键词： Real industrial wastewater,Zinc oxide quantum dots,Solar photocatalytic activity,Recycling process,Sol-gel method
更新于2025-09-23 15:21:01
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Near Infrared Lasera??Annealed IZO Flexible Device as a Sensitive H2S Sensor at Room Temperature
摘要： A metal-oxide material (indium zinc oxide [IZO]) device with near-infrared (NIR) laser annealing was demonstrated on both glass and bendable plastic substrates (polycarbonate, polyethylene, and polyethylene terephthalate). After only 60 s, the sheet resistance of IZO films annealed with a laser was comparable to that of thermal-annealed devices at temperatures in the range of 200°C–300°C (1 hr). XPS, ATR, and AFM were used to investigate the changes in the sheet resistance and correlate them to the composition and morphology of the thin film. Finally, the NIR laser-annealed IZO films were demonstrated to be capable of detecting changes in humidity and serving as a highly sensitive gas sensor of hydrogen sulfide (in parts-per-billion concentration), with room-temperature operation on a bendable substrate.
关键词： IZO,sol-gel,laser annealing,NIR,gas sensor,flexible
更新于2025-09-23 15:21:01
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[IEEE 2019 International Energy and Sustainability Conference (IESC) - Farmingdale, NY, USA (2019.10.17-2019.10.18)] 2019 International Energy and Sustainability Conference (IESC) - Metal oxide-based heterojunction thin films for solar cell applications
摘要： The interest and development in a fully green future towards sustainable technology and environmental preservation has spurred exponentially for the past few years. The adoption in clean energy is underway with solar photovoltaic (PV) technology leading the race. To keep PV sector competitive with current conventionally generated electricity, an alternative economic PV module using cheap materials with low-cost deposition method is needed. Among the candidate, metal oxides (MO) semiconductors are great potential materials to achieve this goal due to its massive availability, non-toxicity, chemically stable, and can be deposited using low-cost techniques at ambient condition. In this report, the p-n junction solar cell was fabricated using layer by layer deposition of n-type and p-type metal oxide semiconductors. Co3O4 and CuO were used as absorbing layers and ZnO as a window layer in contact with each other using simple spin coating deposition method. Photocurrent density (JSC), photo voltage (VOC) and the crystallinity of materials were investigated to characterize their optoelectronic properties. It is observed that Co3O4 shows larger crystallite size compared to CuO at 26.66 nm and 24.86 nm, respectively. Samples consisting of Co3O4 and CuO p-n junction solar cell exhibits high absorbance in the visible spectral region of 350 nm to 750 nm. J-V measurement of FTO/ZnO/Co3O4/In heterojunction films exhibits short-circuit current density of 0.391 mA/cm-1 and open-circuit voltage of 0.476 V under the illumination of AM1.5 solar simulation (100mW/cm2). Meanwhile, FTO/ZnO/CuO/In shows short-circuit current density of 0.429 mA/cm-1 and open-circuit voltage of 0.048 V. Thus, it shows that green materials without any environmental issue has high potential in solar cells application.
关键词： CuO,Co3O4,Sol-Gel,Solar Cell,Spin Coating,Heterojunction
更新于2025-09-23 15:21:01
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Transparent-to-dark photo- and electrochromic gels
摘要： Smart windows in which the transmittance can be controlled on demand are a promising solution for the reduction of energy use in buildings. Windows are often the most energy inefficient part of a building, and so controlling the transmittance has the potential to significantly improve heating costs. Whilst numerous approaches exist, many suitable materials are costly to manufacture and process and so new materials could have a significant impact. Here we describe a gel-based device which is both photo- and electrochromic. The gel matrix is formed by the self-assembly of a naphthalene diimide. The radical anion of the naphthalene diimide can be formed photo or electrochemically, and leads to a desirable transition from transparent to black. The speed of response, low potential needed to generate the radical anion, cyclability of the system, temperature stability and low cost mean these devices may be suitable for applications in smart windows.
关键词： Smart windows,Gel-based device,Naphthalene diimide,Electrochromic,Photochromic
更新于2025-09-23 15:21:01
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Fluorescent Properties of Gd-Doped Zno Nanonporous Networks & Its Application in Optical Biosensing
摘要： This research presents a study of the fluorescent properties of new materials based on gadolinium-doped zinc oxide nanoporous networks obtained by sol gel method on the surface of microcrystalline silicon. The effect of co-doping of different concentrations of Gd ions on the emission properties of ZnO nanoparticles has been investigated. Emissions of such biomolecules as protein, amino acids and porphyrin and its detection limits were studied for the purpose of practical application of Gd-doped ZnO nanonporous networks as an element of an optical biosensor technology.
关键词： sol-gel method,nanoporous networks,optical biosensing,fluorescent properties,Gd-doped ZnO
更新于2025-09-23 15:21:01