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Influencing Optical and Magnetic Properties of NiCr2O4 by the Incorporation of Fe(III) for Cr(III) Following Epoxide Gel Synthesis
摘要： With the objective of modifying the optical and magnetic properties of the spinel NiCr2O4, incorporation of 50 mol.% of Fe3+ for Cr3+ has been attempted following an epoxide-mediated gel synthesis. From the Le Bail re?nement of powder x-ray diffraction patterns of xerogels after calcination at 1000°C for 2 h in Fd-3 m space group, the lattice parameter of resultant spinels showed a marginal increase from 8.3117 (21) for NiCr2O4 to 8.3177 (26) A? for NiCrFeO4. The square morphology of the crystallites was observed in scanning electron microscopic images, and the energy-dispersive spectroscopy results con?rmed the uniform presence of Ni, Cr and Fe in these samples. Lattice fringes in high-resolution transmission electron microscopic images could be related to the cubic spinel structure. The optical band gap was found to decrease from 1.68 for NiCr2O4 to 1.41 eV for NiCrFeO4. Substitution of iron for chromium was found to reduce its catalytic ef?ciency for photo-degradation of aqueous rhodamine-6G (Rh-6G) dye solution under UV–visible radiation.
关键词： x-ray methods,Spinels,magnetic properties,calcination,sol–gel processes
更新于2025-09-09 09:28:46
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Sol-gel synthesis of new ZnFe2O4/Na-bentonite composites for simultaneous oxidation of RhB and reduction of Cr(VI) under visible light irradiation
摘要： To improve the photogenerated charge carrier separation and stability of ZnFe2O4, we prepared new ZnFe2O4/Na-bentonite composites using Na-bentonite as the carrier via a sol-gel method. The composition, surface morphology and optical properties of samples were characterized by XRD, TEM, XPS, FTIR and UV–vis DRS analysis. The results of TEM and XPS show that the ZnFe2O4 nanoparticles spread on the thin layers of Na-bentonite due to intercalation with Na-bentonite. The simultaneous removal of the Cr(VI)-RhB mock wastewater system by ZnFe2O4/Na-bentonite composites, the results are 88.6% for Cr(VI) and 94.2% for RhB in 120 min, which is 1.3-fold higher of Cr(VI) reduction than that of the individual ones. Based on experimental results of PL and reactive species involved in the removal of RhB and Cr(VI), the enhanced photocatalytic activity of the new ZnFe2O4/Na-bentonite composite could be due to visible-light adsorption ability, larger interfacial area, as well as effective transfer and prolonged charge-hole separation.
关键词： Na-bentonite,photocatalytic activity,ZnFe2O4,stability,sol-gel
更新于2025-09-09 09:28:46
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Quantum cutting properties of Tb3+/Yb3+ co-doped ZrO2-SiO2 nano-crystalized glasses synthesized via a sol-gel route
摘要： Tb3+/Yb3+ co-doped ZrO2-SiO2 nano-crystallized glasses were prepared by a sol-gel process. The crystal structure and optical properties including down-conversion photoluminescence (or, quantum cutting) of the Tb3+-Yb3+ system with respect to gel heat treatment temperature were investigated by X-ray diffraction (XRD), Raman, photoluminescence (PL), and PL decay curves analysis. The energy transfer efficiency from Tb3+ to Yb3+ ions, which converts one photon to two photons with lower energy, increased with heat-treatment temperature. Furthermore, the oxidation state of Tb4+ ions was suspected to influence the emission intensity of Tb3+ and energy conversion efficiency. Thus, a post-treatment reduction was applied to the sample heated at 1100 oC by annealing it at 1100 oC for 1 h under 5%H2/95%N2 reductive atmosphere. Consequently, the thermodynamically generated Tb4+ ions were reduced to a trivalent state, leading to higher energy transfer efficiency.
关键词： ZrO2 nanocrystals,Sol-gel method,photoluminescence,quantum cutting,Tb3+-Yb3+ pair,Tb4+ ions
更新于2025-09-09 09:28:46
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Ink-jet printing of a TiO2–10%ZrO2 thin film for oxygen detection using a solution of metal alkoxoacetylacetonates
摘要： A solution of metal alkoxoacetylacetonates in isoamyl alcohol was used as a functional ink for ink-jet printing of TiO2-10%ZrO2 thin nanostructured films. It is shown that the anatase crystal lattice is formed during heat treatment of xerogel thin films in air at a temperature of 500 °C. According to the SEM scanning electron microscopy, the particle size of the resulting films was 10-11 nm. The effect of the number of TiO2-ZrO2 deposited layers on resulting 2D nanomaterial sensitivity to oxygen and other analyte gases (H2, CH4 and CO) at temperatures of 400 and 450 °C is shown.
关键词： Gas sensor,Sol-gel,Titanium dioxide,Additive,Ink-jet printing,Alkoxoacetylacetonate
更新于2025-09-09 09:28:46
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Probing the dielectric, piezoelectric and magnetic behavior of CoFe2O4/BNT-BT0.08 composite thin film fabricated by sol-gel and spin-coating methods
摘要： We investigated in this paper a novel bilayer composite obtained by sol-gel and spin coating of the ferroelectric 0.92Na0.5Bi0.5TiO3–0.08BaTiO3 (abbreviated as BNT-BT0.08) and ferromagnetic CoFe2O4 phases, for miniature low-frequency magnetic sensors and piezoelectric sensors. This heterostructure, deposited on Si-Pt substrate (Si-Pt/CoFe2O4/BNT-BT0.08), was characterized using selected method such as: X-ray diffraction, dielectric spectroscopy, piezoelectric force microscopy, SQUID magnetometry, atomic force microscopy/magnetic force microscopy, and advanced methods of transmission electron microscopy. CoFe2O4/BNT-BT0.08 ferromagnetic–piezoelectric thin films show good magnetization, dielectric constant and piezoelectric response. The results of analyses and measurements reveal that this heterostructure can have applications in high-performance magnetoelectric devices at room temperature.
关键词： ferroelectric,spin coating,ferromagnetic,bilayer composite,magnetoelectric devices,sol-gel
更新于2025-09-09 09:28:46
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Fabrication and analysis of the structural phase transition of ZrO <sub/>2</sub> nanoparticles using modified facile sol–gel route
摘要： The synthesis of zirconia nanoparticles is achieved through a modified facile sol–gel route. The as-prepared gel is analyzed thermally using TGA and DTA techniques to spot the crystallization process of zirconia nanoparticles. The prepared gel is then annealed at different temperatures and the structure was found to change between tetragonal and monoclinic crystal systems. The first stable tetragonal phase is achieved after annealing for 2 h at 400°C. The annealed powders between 600°C and 800°C demonstrate mixed tetragonal/monoclinic phases. Annealing at 1000°C and higher temperatures up to 1200°C resulted in pure monoclinic phase. Cubic phase was not detected within the annealing temperature range in this study. The elemental analysis of the annealed powder confirmed the formation of zirconia nanoparticles with the chemical formula ZrO2. The FTIR spectra of the annealed samples introduced a variation in the vibrational bands especially around the phase transition temperature. HR-TEM images reported the formation of nano-zirconia crystals with apparently large particle sizes. The optical energy gap of zirconia nanoparticles is investigated and determined.
关键词： ZrO2 nanoparticles,HR-TEM,sol–gel synthesis,EDAX,optical energy gap
更新于2025-09-09 09:28:46
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Improved Negative Bias Stress Stability of Sol-Gel-Processed Mg-Doped In <sub/>2</sub> O <sub/>3</sub> Thin Film Transistors
摘要： We demonstrate sol–gel-processed Mg-doped In2O3 thin film transistors (TFTs) with high performance and improved stability. To improve the performance of indium oxide, which is unstable at a high negative threshold voltage, magnesium is used to suppress oxygen vacancy formation. As the Mg doping concentration increases, the oxygen deficiencies and OH impurities decrease, resulting in a positive shift in the threshold voltage and improved stability in negative bias stress environments. In this experiment, Mg-doped (0 to 2 wt%) indium oxide TFTs are fabricated. Indium oxide prepared from a synthesized solution of an indium nitrate hydrate precursor and 2-methoxyethanol has a mobility of 17.2 cm2/V s. In2O3 TFTs doped with 1 wt% Mg also show a high mobility of 11.02 cm2/V s and a noticeable ?1.5 V threshold voltage shift under negative bias stress. Our results suggest that the sol–gel-processed Mg-doped In2O3 TFTs are a promising candidate for use in high-stability and high-performance applications in transparent devices.
关键词： thin film transistors,negative bias stress,Mg doping,Sol-gel,In2O3
更新于2025-09-09 09:28:46
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Impact of Overlapping Fe/TiO <sub/>2</sub> Prepared by Sol-Gel and Dip-Coating Process on CO <sub/>2</sub> Reduction
摘要： Fe-doped TiO2 (Fe/TiO2) film photocatalyst was prepared by sol-gel and dip-coating process to extend its photoresponsivity to the visible spectrum. To promote the CO2 reduction performance with the photocatalyst, some types of base materials used for coating Fe/TiO2, which were netlike glass fiber and Cu disc, were investigated. The characterization of prepared Fe/TiO2 film coated on netlike glass fiber and Cu disc was analyzed by SEM and EPMA. In addition, the CO2 reduction performance of Fe/TiO2 film coated on netlike glass disc, Cu disc, and their overlap was tested under a Xe lamp with or without ultraviolet (UV) light, respectively. The results show that the concentration of produced CO increases by Fe doping irrespective of base material used under the illumination condition with UV light as well as that without UV light. Since the electron transfer between two overlapped photocatalysts is promoted, the peak concentration of CO for the Fe/TiO2 double overlapping is approximately 1.5 times as large as the Fe/TiO2 single overlapping under the illumination condition with UV light, while the promotion ratio is approximately 1.1 times under that without UV light.
关键词： UV light,Fe-doped TiO2,visible spectrum,photocatalyst,dip-coating,sol-gel,CO2 reduction
更新于2025-09-09 09:28:46
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Study on the Light Stability of Poly(p-phenylenebenzobisoxazole) Fiber
摘要： Although poly(p-phenylenebenzobisoxazole) (PBO) fiber has outstanding mechanical performances and thermal stability but its application was hindered seriously due to low light stability. Thus, main aim in present work is to increase the light stability of PBO fiber. Four means, such as reacted sol-gel means, mixed sol-gel means, silane sol-gel means and physical adhesion means, were performed for light stabilizers to adhere on the surface of PBO fiber. The experimental results indicate that the PBO fibers processed by reacted sol-gel means exhibit flat surface without obvious particle accumulation. Contrasted with those fibers processed by other three means, these fibers show better light stability. After 130 h of light irradiation, the mechanical tensile strength of the fibers processed by reacted sol-gel means is still over 75 % of strength of unaged fiber and the strength is much higher than the aged original fibers whose strength is ca. 40 % of that of unaged original fiber.
关键词： Reacted sol-gel means,Mixed sol-gel means,Ferrocenecarboxylic acid
更新于2025-09-04 15:30:14
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Nanostructured Titania Templated by Natural Cellulose Substance: Effect of Vanadium-Doping on the Anatase-to-Rutile Phase Transformation
摘要： Vanadium-doped rutile titania nanomaterial was synthesized by calcination of titania/vanadia composite thin gel films pre-coated natural cellulose substance (e.g., ordinary filter paper) at a relatively low temperature (600 °C). A better mixture of titanium and vanadium species is achieved during the layer-by-layer (LbL) deposition process with cellulose nanofiber as a template, leading to more vanadium dopants incorporated in the titania crystal lattices. By sufficient vanadium-doping, the phase transformation temperature from anatase to rutile phase of titania is decreased effectively. The doping mode and existing state of vanadium in the titania nanomaterials and the effect on the anatase-to-rutile phase transformation have been studied. This strategy provides a facile and effective route to facilitate the phase transformation of various nanostructured metal oxides templated by natural cellulose substance through doping appropriate functional metal ions in the LbL deposition process.
关键词： Biomimetic,Ceramics,Sol–Gel Preparation,Phase Transformation,Titania
更新于2025-09-04 15:30:14