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Magneto-structural properties and photocatalytic performance of sol-gel synthesized cobalt substituted Ni Cu ferrites for degradation of methylene blue under sunlight
摘要： In this study, Ni0.5-xCoxCu0.5Fe2O4 (with x varying from 0.0 to 0.5) ferrites have been synthesized by a sol-gel auto-combustion method using urea as fuel. The influence of Cobalt (Co2+) content on the structural, optical and magnetic Ni-Cu ferrites was studied by X-ray diffraction (XRD) patterns, Fourier Transform Infrared Spectroscopy (FT-IR), UV-Vis Spectroscopy (UV-DRS) and vibrating sample magnetometer (VSM). Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX) analysis have been used to determine morphology and compositions respectively. The X-ray diffraction studies have been carried out by considering the distance between adjacent crystal planes, lattice constant and average crystallite size which decrease from 44-35 nm with substitution of Co2+. FT-IR spectra show two major stretching bands around 400-600 cm-1. The magnetic parameters were measured at room temperature where increase in saturation magnetization was observed with increase in concentration of Co2+ in Ni-Cu ferrites. The photocatalytic performance study of Co2+ substituted Ni-Cu ferrites was carried out under visible and direct sunlight on methylene blue (MB) dye. The increase in degradation percentage was observed with Co2+ substitution in both visible and sunlight. The catalyst was found to be more efficient in sunlight with 91% degradation of MB within 120 minutes.
关键词： SEM,VSM,Ni-Co-Cu Ferrites,XRD,Sol-Gel Auto-Combustion,Photocatalyst
更新于2025-09-09 09:28:46
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Solar Energy Absorbing Materials that are Capable of Withstanding Long-Term Exposure at 600 °C: Research Strategy
摘要： Pipes for parabolic-trough solar energy collectors (PTSC) must be able to operate and withstand high temperatures in corrosive environments for a long time without changing its microstructure and losing its original properties. The stages of development of a new material and technology for solar energy collectors that allows the production of a PTSC solar energy-absorbing material that is capable of withstanding temperatures ≥ 600 °C for at least 250 days are described. This material is a glass-crystalline enamel coating that is adhered to tubular stainless steel pipes. Such enamel coatings have high coefficients of thermal expansion (CTE) that are similar to the metal surface. These matching CTEs allow the enamel coatings to resist flaking during the heating at 900 °C. The high-temperature resistance of the developed coating was ensured not only by specific additives added to the frit of the coating but also by an additional nanosized sol-gel coating over the enamelled metal substrate.
关键词： thermal properties,enamel coatings for steel,anti-reflective coatings,sol-gel coatings
更新于2025-09-09 09:28:46
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Research on cracking of SiO2 nanofilms prepared by the sol-gel method
摘要： SiO2 nano?lms were prepared by a sol-gel method with TEOS as the precursor, ethanol as the solvent, and hydrochloric acid as the catalyst. The in?uences of H2O, EtOH, and HCl on the surface of SiO2 ?lm were studied by a controlled variable method, and the e?ects of aging time, spin-coating speed, ammonia treatment, heat treatment, and substrate on the ?lms were also determined experimentally. Crack-free SiO2 nano?lms with tens of microns thickness were repeatedly fabricated using the optimizing parameters, and the size of SiO2 nano-particles was in the range of 100–500 nm.
关键词： SiO2 nano?lm,Sol-gel method
更新于2025-09-09 09:28:46
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Structural, Infrared, Magnetic, and Electrical Properties of Ni0.6Cd0.2Cu0.2Fe2O4 Ferrites Synthesized Using Sol-Gel Method Under Different Sintering Temperatures
摘要： Ni0.6Cd0.2Cu0.2Fe2O4 ferrites were synthesized using sol-gel method under different sintering temperatures. XRD patterns with the Rietveld refinement indicate that samples crystallize in the cubic spinel structure. The increase of sintering temperature leads successively to the increase of lattice constant, average crystallite size, intensities of absorption bands, magnetization, and electrical conductivity of the prepared ferrites. Dielectric constants decrease with frequency and their behaviors have been investigated using the interfacial polarization theory predicted by Maxwell. The modulus analysis shows the presence of electrical relaxation phenomenon and non-Debye nature for the samples. An appropriate electrical equivalent circuit was used to analyze the Nyquist plots, and the results show that the conduction mechanism of the synthesized ferrites is mainly due to the grain boundary contribution.
关键词： Ferrites,conductivity,Rietveld refinement,Sol-gel method,Infrared properties,Dielectric properties
更新于2025-09-09 09:28:46
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Microstructural, optical, and electrical characteristics of Ni/C doped BST thin films
摘要： In the present work the effect of simultaneous doping of carbon and nickel on the microstructural, optical, and electrical properties of barium strontium titanate (BST) is investigated. Thin films of BST were prepared by the sol-gel method in six different compositions ((Ba0.6Sr0.4)(NixCyTi1-x-y)O3): x = y = 0.00 (BST), x = 0.04 y = 0.00 (BST4N), x = 0.04 y = 0.01 (BST4N-1C), x = 0.04 y = 0.02 (BST4N-2C), x = 0.04 y = 0.03 (BST4N-3C), and x = y = 0.04 (BST4N-4C). Structural features and chemical bonds of the films were studied by TGA/DSC, XRD, FT-IR, and FE-SEM. The electrical and optical properties of the films were analysed by impedance spectroscopy and UV–VIS spectroscopy. The results show that addition of Ni and C leads to Ti4+-Ni2+ and Ti4+-C4+ replacements, respectively. These replacements lead to a gradual increase in the band gap energy; from 3.15 eV for BST to 3.44, 3.5, 3.66, 3.73 and 3.76 eV for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. In contrast, the dielectric loss decreases significantly from 0.055 for BST to 0.031, 0.033, 0.03, 0.022 and 0.01 for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. At the same time, the quality factor Qf (1/ tanδ) increases substantially from 15 for BST to 32, 30, 33, 44 and 87 for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. In contrast, the frequency dependence of the capacity decreases in comparison to un-doped BST. Among all films, the BST4N-4C had the highest figure of merit (FOM), least dielectric loss, and very low frequency-dependence, making it the best candidate for tuneable device applications.
关键词： Ion doping,Sol-gel,Thin-film,BaSrTiO3,Dielectric properties,Optical properties
更新于2025-09-09 09:28:46
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Optical Characteristics of Strontium Titanate Films Obtained by the Sol–Gel Method
摘要： Using data of multiangle spectrophotometry and spectral ellipsometry in the UV and visible ranges, spectra of the refractive indices and absorption coefficients and width of the forbidden band of one- and five-layer strontium titanate films obtained by the sol–gel method have been calculated. Layer-by-layer deposition of sol on quartz substrates, from one to five layers, leads to an increase in film porosity from 4 to 33%. This causes a decrease in the refractive indices in the middle part of the visible spectrum from 2.33 to 1.87, which leads to a decrease in the reflectance and an increase in the transmittance or transparency of five-layer films. With an increase in the heating temperature of such films from 500 to 750°C, a shift of the absorption band maximum from 239 to 253 nm takes place and the optical width of the forbidden band decreases from 4.63 to 4.20 eV. The absorption band maximum of the single-layer film falls on the wavelength of 252 nm, and its optical width of the forbidden band is 3.96 eV.
关键词： Strontium titanate films,optical characteristics,forbidden band width,sol–gel method,refractive indices,absorption coefficients
更新于2025-09-09 09:28:46
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Influence of the Heat Treatment on the Particles Size and on the Crystalline Phase of TiO2 Synthesized by the Sol-Gel Method
摘要： Titanium biomaterials’ response has been recognized to be affected by particles size, crystal structure, and surface properties. Chemical and structural properties of these nanoparticle materials are important, but their size is the key aspect. The aim of this study is the synthesis of TiO2 nanoparticles by the sol-gel method, which is an ideal technique to prepare nanomaterials at low temperature. The heat treatment can affect the structure of the ?nal product and consequently its biological properties. For this reason, the chemical structure of the TiO2 nanoparticles synthesized was investigated after each heat treatment, in order to evaluate the presence of different phases formed among the nanoparticles. FTIR spectroscopy and XRD have been used to evaluate the different structures. The results of these analyses suggest that an increase of the calcination temperature induces the formation of mixed-crystalline-phases with different content of anatase and rutile phases. The results obtained by SEM measurements suggest that an increase in the particles size accompanied by a noticeable aggregation of TiO2 nanoparticles is due to high temperatures achieved during the thermal treatments and con?rmed the presence of different content of the two crystalline phases of titanium dioxide.
关键词： titania,sol-gel method,rutile,FTIR,nanoparticles size,anatase
更新于2025-09-09 09:28:46
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Structure Analysis and Ferroelectric Response of Bi <sub/>0.5</sub> Na <sub/>0.5</sub> TiO <sub/>3</sub> Nanopowder Synthesized by Sol–Gel Method
摘要： In this work, bismuth sodium titanate, Bi0(cid:2)5 ± xNa0(cid:2)5 ± y TiO3 (BNT, x(cid:3) y = ?0(cid:2)05–0.08) nanopowders were produced using the low-temperature sol–gel technique. The effects of de?cient and excess amounts of Bi and Na on BNT structure were systemically examined through X-ray powder diffraction (XRD), energy dispersive analysis (EDS) and scanning electron microscope (SEM). The optimized composition of the BNT nanopowder was pelletized and sintered at different temperatures (950 (cid:3)C–1150 (cid:3)C). Highly dense ceramics possessing pure perovskite phase was observed for the sample sintered at an optimum sintering temperature (1100 (cid:3)C). The ferroelectric properties were found to increase with an increase in sintering temperature up to 1100 (cid:3)C and then decrease. This study justi?es that Bi and Na non-stoichiometry (proper excess), processing and sintering temperatures play important role in the successful synthesis of BNT ceramics.
关键词： Nanopowders,Sol–Gel,Ferroelectric,Calcination Temperature
更新于2025-09-09 09:28:46
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Ni and Co Substituted Zinc Ferri-chromite: A Study of their Influence in Photocatalytic Performance
摘要： Enhanced photocatalytic activity was demonstrated in the present study for two systems i.e., Zn1-xNixFeCrO4 and Zn1-xCoxFeCrO4 (0.0 ≤ x ≤ 1.0) in photo degradation of methyl orange, methyl red and congo red dyes. The basic aim of this study is to find a suitable compound of doped zinc ferrichromite as photocatalyst for degradation of organic dyes. A sol-gel process used for synthesis of crystalline nanopowders gave better photocatalytic activity under the UV light radiations. The result showed that, dyes undergo fast degradation with UV light in presence of doped compounds. The rate of degradation of dyes was estimated spectro-photometrically from residual concentration in dyes.
关键词： Surface area,synthesis,Pore volume,Photocatalytic activity,Sol-gel
更新于2025-09-09 09:28:46
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Effect of polyethylene glycol and propyltrimethoxysilane on structural and optical properties of zinc oxide nanoparticles synthesized by sol–gel process
摘要： Zinc oxide nanoparticles (ZnO NPs) are prepared by sol–gel process, using both polyethylene glycol (PEG-400) as surfactant and propyltrimethoxysilane (PTMS) as capping agent. Surface modi?cation is performed in situ procedure. The physical parameters such as strain and stress values are calculated via the Williamson–Hall plot (W&H) assuming a uniform deformation model (UDM) and uniform stress deformation model, and by the size and strain plot method (SSP). The results show that the crystallite size estimated from Scherrer’s formula, (W&H), (UDM), (SSP) and the particle size estimated from DSL are inter-correlated, which con?rm the small size and the isotropic nature of our ZnO NPs. The FTIR spectroscopy illustrates that PEG-400 and PTMS could be adsorbed at the ZnO NPs surface. The distinct emission peak in the blue band is located at 490 nm and E2 (high) mode is situated at 436 cm-1. Both results con?rm the oxygen de?ciency in the ZnO NPs.
关键词： Propyltrimethoxysilane,Sol–gel synthesis,Zinc oxide,Nanoparticles,PEG-400,DRX
更新于2025-09-09 09:28:46