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Influence of silicon dioxide medium on the structural and electrical properties of nickel zinc ferrite
摘要： Nickel zinc ferrite [(Ni 0:65 Zn 0:35 Fe 2 O 4)x / (SiO 2)1(cid:0)x where, x = 1.0, 0.85, 0.65, 0.50, 0.35, and 0.15] is synthesized using the glyoxylate precursor method. The synthesis, characterization, and electrical study of nickel zinc ferrites/SiO 2 powder with low dielectric constant, very low conductivity, and loss tangent with low frequency dispersion, suitable for good insulators, is reported here. X-ray diffraction, TGA, and FT-IR studies are employed for identifying crystalline phases and structure. Crystallite size is calculated by the Scherrer formula and Williamson–Hall equation and found to fall in the range of 4.9–25 nm. TEM of the samples shows spherical particles of uniform size distribution and the spotty rings of SAED patterns are analyzed for identifying the crystal planes. The study confirms a simple and efficient way to synthesize single-phase nickel zinc ferrite (NZFO) spherical particles of nano size ( (cid:25) 15 nm at 1000 ? C) with lower particle agglomeration in comparison to any other methods. Electrical studies are carried out using an LCR meter. The observed value of dielectric constant falls in the range of 10–80, loss tangent in the range of 0.05–0.4, and electrical conductivity in the range of 10 (cid:0)4 to 10 (cid:0)7 mho m (cid:0)1 . These values are respectively functions of temperature, frequency, and the ferrite content in ferrite/SiO 2 samples. A proper selection of ferrite concentration in the silica medium enables one to prepare NZFO/SiO 2 material of very low loss tangent with dielectric constant in the range of 10–80.
关键词： tetraethyl orthosilicate,dielectric constant,Nickel zinc ferrite,dielectric conductivity,loss tangent,ethylene glycol
更新于2025-09-23 15:21:21
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One-step synthesis and deposition of ZnFe2O4 related composite films via SPPS route for photodegradation application
摘要： Binary spinel-type metal oxides (AB2O4) related materials, including ferrites (AFe2O4), are attractive photocatalysts thanks to their excellent visible light response for the photodegradation of organic pollutants. Currently, these materials are synthesized via conventional chemical routes suffering from long preparation duration and multistep. Solution Precursor Plasma Spray (SPPS) process is a single-step method for depositing photocatalytically active zinc ferrite-based films within several minutes. The influence of the precursor ratio on the microstructures and phase compositions of the ZnFe2O4 films was investigated by XRD and Raman analyses. In addition, two optimized ZnFe2O4 films were prepared by increasing the ZnO loading and tailoring injection pattern of the precursor solution. The surface morphologies and optical bandgap were also determined by SEM and UV-visible spectroscopy. The photocatalytic activities of the ZnFe2O4 films were evaluated through the degradation of the Orange II dye and of tetracycline hydrochloride under UV or visible light irradiation. The results show that compositional ratios and composition distribution of the ZnFe2O4 films prepared via SPPS played a key role on the photocatalytic activity. The SPPS route was demonstrated to be a promising method for the synthesis and the deposition of metal oxide (i.e. perovskite type and spinel type) films within a single-step for functional applications.
关键词： Solution Precursor Plasma Spray,Photocatalytic degradation,zinc ferrite,composite films
更新于2025-09-23 15:21:01
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Z-scheme recyclable photocatalysts based on flower-like nickel zinc ferrite nanoparticles/ZnO nanorods: Enhanced activity under UV and visible irradiation
摘要： Hybrid photocatalysts with magnetism are important because of their advantage of being recyclable by a magnet. In this paper, we report the synthesis of magnetic flower-like nanocomposites based on ZnO nanorods and nickel zinc ferrite (NZF) nanoparticles using a hydrothermal method. The magnetic cores of NZF nanoparticles with diameter of 30e50 nm were used as the centers for the subsequent ZnO nanorods growth. ZnO nanorods grow from these magnetic cores to form scattered flower-like nanostructures, while their length is controlled by changing the heating time. These flower-like nanostructures have distinctive morphology with large surface-to-volume (S/V) ratio. When used as a photocatalyst, these hierarchical nanocomposites show high photocatalytic activity in the degradation of organic contaminates under ultraviolet (UV) and visible light irradiation. Their excellent photocatalysis attributes to the wide absorption range of NZF and the simple Z-scheme system between ZnO and NZF that enhances the charge separation efficiency. In addition, these nanocomposites present sufficient magnetization such that they can be rapidly separated from the solution by a magnet. These recyclable photocatalysts with high efficiency under UV and visible light are ideal for purifying organic contaminants.
关键词： Photocatalyst,Recyclable,Nickel zinc ferrite
更新于2025-09-23 15:21:01
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Effect of the degree of inversion on optical properties of spinel ZnFe <sub/>2</sub> O <sub/>4</sub>
摘要： Spinel ferrites (T[M1?xFex]O[MxFe2?x]O4 with 0 ≤ x ≤ 1, where M is a bivalent metal ion and the superscripts denote tetrahedral and octahedral sites) are materials commonly used in electronics due to their outstanding magnetic properties. Thus, the effect of the degree of inversion, x, on these properties is well known. However, its effect on other properties of these materials has rarely been investigated in detail. Since ferrites gained much attention during the last decade as visible light active photocatalysts and photoelectrocatalysts, understanding the effect of the degree of inversion on the optical properties became necessary. Among photocatalytically and photoelectrocatalytically active spinel ferrites, zinc-ferrite (ZnFe2O4, ZFO) is one of the most widely studied materials. In this work, five ZFO samples with degrees of inversion varying from 0.07 to 0.20 were prepared by a solid-state reaction employing different annealing temperatures and subsequent quenching. Raman and UV-Vis-NIR spectra were measured and analyzed together with theoretical results obtained from ab initio calculations. Changes in the UV-Vis-NIR spectra associated with electronic transitions of tetrahedrally and octahedrally coordinated Fe3+ ions are distinguished. However, the optical band gap of the material remains unchanged as the degree of inversion varies. Based on the experimental and theoretical results, a new assignment for the Raman active internal modes and the electronic transitions of ZFO is proposed.
关键词： ab initio calculations,degree of inversion,zinc ferrite,spinel ferrites,optical properties,UV-Vis-NIR spectroscopy,Raman spectroscopy
更新于2025-09-19 17:15:36
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Dielectric and electro-optical properties of zinc ferrite nanoparticles dispersed nematic liquid crystal 4’-Heptyl-4-biphenylcarbonnitrile
摘要： In this work, comprehensive results on dielectric and electro-optical properties of pristine and zinc ferrite (ZnFe2O4) nanoparticles (NPs) dispersed in host nematic 4?-Heptyl-4-biphenylcarbonnitrile (7CB) systems are reported. The dielectric and EO properties of pristine and NPs dispersed (concentrations 0.05, 0.1, 0.15, 0.2, 0.3 and 0.5 wt%) into the host nematic system have been studied. We have seen uniform NPs dispersion into nematic 7CB up to 0.15 wt% concentration of NPs by the POM. The NPs aggregation starts at 0.2 wt% dispersion. It is shown that the dielectric and electro-optical properties are strongly in?uenced by the concentration of NPs in host nematic and applied electric ?eld. The dielectric anisotropy is maximum for the NPs dispersed system of 0.15 wt% concentration. The Birefringence, parallel and perpendicular components of permittivity and conductivity are found to be dependent on temperature and concentration of NPs into host matrix. In pure nematic material, small memory is seen but in NPs dispersed systems noticeable memory is found. In particular, pronounced memory is found for the dispersed system of 0.3 wt% concentration of NPs.
关键词： Nematic liquid crystal,zinc ferrite nanoparticles,birefringence,splay elastic constant,dielectric anisotropy
更新于2025-09-12 10:27:22
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Microwave-Assisted Hydrothermal Synthesis of ZnFe<sub>2</sub>O<sub>4</sub>/TiO<sub>2</sub> Composite and Photocatalytic Properties
摘要： In order to improve TiO2 photocatalytic activity ZnFe2O4/TiO2 nanocomposites with different ZnFe2O4 mass loading were produced. Obtained ZnFe2O4 nanoparticles were coupled with TiO2 via microwave-assisted hydrothermal method in order to improve photon absorption in a range of visible light. Prepared nanostructures were characterized with scanning electron microscopy and X-ray diffraction. Photocatalytic activity of prepared samples was investigated by degradation of methylene blue under different light sources – LED, Hg and Osram Vitalux lamps. ZnFe2O4 consisted of spherical nanoparticles with average size of 15 nm. TiO2 spherical nanoparticles size was in a range of 30÷45 nm. The results shown that doping TiO2 with ZnFe2O4 nanoparticles increased photocatalytic activity. Photocatalytic activity increases as mass loading of ZnFe2O4 decreased.
关键词： titania,zinc ferrite,hydrothermal,photocatalysis,nanocomposite
更新于2025-09-09 09:28:46