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Prepara??o e caracteriza??o de espinélio MgAl2O4 nanoestruturado através de síntese por combust?o em solu??o
摘要： This study aimed to investigate the synthesis and characterization of nanostructured MgAl2O4 spinel by different routes of combustion in solution. The MgAl2O4 spinel was synthesized using aluminum nitrate and magnesium nitrate as the sources of metal cations and sucrose as fuel in continuous combustion system (SCCS), and sequencing batch (CS), followed by heat treatment. The obtained powders were characterized by thermogravimetric analysis, gas adsorption for surface area analysis, laser diffraction for particle size measurement, X-ray diffraction, transmission electron microscopy for crystallographic analysis, and scanning electron microscopy (SEM) for powder morphology analysis. Both routes provided high purity powders and nanosized crystallites in the form of micrometric aggregates, whose properties varied depending on the oxide/fuel ratio. The SEM analyzes confirmed the aggregation of powder particles, as particles with irregular and porous morphology. The SCCS route resulted in a powder with similar properties to the CS route with the advantage of being a continuous process with high potential for industrial scale production.
关键词： nanostructured materials,combustion in solution,MgAl2O4 spinel
更新于2025-09-10 09:29:36
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Effect of B2O3 Content on Eu3+?Surrounding in The System SrO?x.B2O3 Containing Eu3+ Ions Prepared by Combustion Method
摘要： The change of Eu3+? surrounding in the system SrO?x.B2O3 with various x values (x = 0.33, 0.5, 1) synthesized by combustion method was investigated via photoluminescence (PL) spectra and phonon sideband (PSB) spectra. From the analysis of PSB spectra, it is reasonable to suggest that when increasing B2O3 content the electron?phonon coupling strength increases due to the increase in the number of B?O? non?bridging bond. By using Judd?Ofelt (JO) theory for PL spectra of Eu3+ ion, the ?2 intensity parameter was calculated and it also shows the asymmetry of Eu3+? surrounding increase corresponding to the B2O3 content.
关键词： Eu3+,Judd?Ofelt theory,Combustion method,electron-phonon coupling,B2O3,phonon sideband
更新于2025-09-09 09:28:46
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Physicochemical study of multicolor BCNO phosphors using a urea combustion method
摘要： In this study, the physicochemical properties of BCNO phosphors were investigated based on the color of luminescence to study the luminescence mechanism. Multicolor BCNOs were synthesized by urea combustion methods using boron, carbon, and nitrogen sources consisting of boric acid, PEG 20k, and urea, respectively. The C/B ratio was varied from 0.3 to 2 with temperature variation between 700 and 800 °C, and synthesis time variation at 30 min, 45 min and 60 min. The synthesis process at 775 °C for 30 min with C/B 0.5 and at 750 °C for 45 min with C/B 1 produced samples with three different luminescent colors (violet-blue-yellow and blue-yellow-green respectively), where each color could be separated conventionally. The measurement of luminescence using a PL spectrometer showed photoluminescence at 413–485 nm for the 775 °C sample and 432–511 nm for the 750 °C sample. In the 775 °C sample, PL of sample red-shifted from violet to green, while the 750 °C sample red-shifted from blue to yellow. The result of the x-ray diffraction analysis (XRD) showed the h-BN phase shifting to a red wavelength from blue to yellow sample. The characterization of chemical functional groups using FTIR showed a wide B–N bond and increasingly sharp bonds of C=N, B–C, and B–N–B from yellow to blue sample. The morphology of the three different colors of the samples looked similar, with an irregular structure, but its EDX characterization showed an increasing B/N ratio for the green to blue sample. From these results, it can be concluded that the characteristics of BCNO are in?uenced by h-BN phase, where an increase of B/N leads to the photoluminescence shifting to blue.
关键词： BCNO,urea combustion method,multicolor luminescence
更新于2025-09-09 09:28:46
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An efficient fabrication of ZnO–carbon nanocomposites with enhanced photocatalytic activity and superior photostability
摘要： Synthesis of carbon nanoparticles (CNPs) and their composite with ZnO has proposed for the first time by combustion of camphor and chemical precipitation method. TEM image shows the surface of ZnO covered by tiny CNPs and acts as structure directing agent that transforms ZnO nanorods to uniform spherical ZnO. CNPs play a vital role to improve the photocatalytic activity and photostability of ZnO up to five runs due to impeding the photo-corrosion of ZnO. Enhance in the photocatalytic activity of ZnO–carbon nanocomposite could be attributed to the excellent dye adsorption capacity, direct photooxidation of dye and suppression of photoinduced electron–hole recombination. The presence of CNPs in nanocomposite served as the main role in accepting the photogenerated electrons due to electronic interaction between ZnO and CNPs. The cytotoxicity studies of meristematic root tip cells of Allium cepa reveals that photocatalytically degraded products were less toxic.
关键词： Photostability,ZnO–carbon nanocomposites,Photocatalytic activity,Chemical precipitation method,Camphor combustion
更新于2025-09-09 09:28:46
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Photoluminescent and structural properties of color tunable trivalent europium doped SrGdAlO4 nanophosphors
摘要： A series of Eu3+ ion doped SrGdAlO4 nanophosphors were prepared via solution combustion technique utilizing urea as a fuel. Structural properties of the tetragonal phase of the host/doped lattice belonging to the space group I4/mmm were characterized by powder X-ray diffraction (PXRD). Photoluminescence spectra, decay curves, UV–Visible diffuse reflectance spectra (UV–Vis DRS) and Judd–Ofelt analysis were utilized to characterize the photoluminescent properties. The radiative rates (Ar), branching ratios (Br) and intensity parameters (?λ) were estimated by Judd–Ofelt analysis. The optimal doping concentration of europium ions for SrGdAlO4 host lattice was found to be 20 mol%, above which concentration quenching was observed due to dipole–dipole interactions. CIE coordinates values lie in the blue region at lower concentrations of Eu3+ ions, which shifted towards white and then to reddish-orange region with higher concentrations of Eu3+ ions, suggesting the color tunable property of the synthesized nanophosphors. Lower value of CCT and color tunable phenomenon proved it as potential candidate for warm white light and phosphor converted white light emitting diodes (Pc-WLEDs) applications. The optical band gap of both host lattice (5.50 eV) as well as of 20 mol% Eu3+ doped SrGdAlO4 nanophosphors (5.26 eV) lie in the range of semiconductors which enhanced their areas of applications.
关键词： Nanophosphors,Color tunability,Solution combustion,Photoluminescence,Judd–Ofelt analysis,Semiconductor
更新于2025-09-09 09:28:46
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Comparative study of photoluminescence of single and mixed phase ZrTiO4 prepared by solution combustion and polymeric precursor method
摘要： This work aims to study synthesis methods and photoluminescence properties of ZrTiO4. Wet chemical routes used for synthesis are solution combustion method and polymeric precursor method. Urea and glycine are two different fuels used in solution combustion synthesis. Scanning Electron Microscope studies con?rms that morphology of the nanoparticles depends on synthesis method. Photoluminescent property depends on the phase of the material, rather than the method of synthesis. Characterization such as X-ray diffraction, SEM, Re?ectance and Photoluminescence studies prove the role of synthesis methods on the properties of the ZrTiO4. Both upconversion and down conversion luminescence have been achieved by synthesizing ZrTiO4 from solution combustion method using urea as fuel, where ZrTiO4 exists in mixed phase.
关键词： Polymeric precursor method, (PPM),Photoluminescence,Single phase,Mixed phase,ZrTiO4,Solution combustion method, (SCS)
更新于2025-09-09 09:28:46
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Comparison of vanadium oxide thin films deposited from commercial and solution combustion synthesised powders
摘要： In the present work, V2O5 thin films were fabricated with both commercial and solution combustion synthesised V2O5 resorting to a single spin coating sol–gel deposition. Structural and morphological properties of V2O5 powder were investigated first, subsequently followed by a detailed investigation of the optical and electrochemical properties of thin films. The film, which was coated from as-synthetised powder onto corning substrate had a transparency of greater than 85% in the visible region for sol–gels exhibited absorption edges at ～380 nm. The optical band-gap energy was evaluated to be 2.7 eV, while the coloration efficiency of this film was found to be 36.8 cm2 C?1. The film thickness range of 100–300 nm was demonstrated in 1-layer. The main properties of the afore discussed thin films provide further encouragement for application in future nanoscale (opto-) electronic devices as they are reproducible, cost-effective, and quick to fabricate.
关键词： electrochemical properties,optical properties,vanadium pentoxide,sol–gel coating,Solution combustion synthesis,thin film
更新于2025-09-09 09:28:46
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Synthesis of nanocrystalline bismuth oxide and its visible photocatalytic activity in the degradation of an organic dye
摘要： Bismuth oxide powder was synthesized, characterized and employed as a visible light photocatalyst for the degradation of aqueous solutions of Orange G (OG), a mono azo dye that is a commonly used colouring agent in various industrial applications. A simple combustion method using urea as fuel was employed to synthesize the metal oxide nanopowders. The prepared material was found to be nanocrystalline in nature as confirmed by XRD analysis. The band gap energy of the material is calculated by plotting (Ah(cid:1))2 vs. h(cid:1) from the UV-DRS spectrum and it is found to be 2.7 eV. The surface morphology and roughness of the material was studied by FE-SEM and AFM techniques. XPS and EDAX studies confirmed the elemental purity and presence in the nanomaterial. Preliminary studies were carried out in order to optimize the solution pH, catalyst dosage and initial dye concentration. As the catalyst possessed good activity at all pH values, thereafter all the photocatalytic reactions were carried out at neutral pH to make the process less cumbersome and cost effective. An optimum catalyst dosage of 1.5 g/L was fixed for a dye solution of 5 mg/L concentration. Kinetic studies showed the photo-degradation to follow pseudo-first order kinetics. Studies on the effect of electrolytes in solution showed that there was a decrease in the efficiency of the catalyst in the presence of the electrolytes. Reusability studies were performed on the catalyst to estimate the economic viability of the system.
关键词： visible light,combustion method,Bismuth oxide,Orange G,photocatalysis
更新于2025-09-09 09:28:46
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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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Tuning the optical properties of ZnO:Cd by doping La and Y
摘要： Zinc oxide doped with Cadmium and rare earth elements synthesized by solgel auto combustion route is reported in this work. The studies have been carried out to analyze the structural, morphological and optical properties of Cd doped ZnO and rare earth doped ZnCdO. The XRD analysis reveals that the addition of rare earth impurity decreases the particle size of ZnCdO. La doped ZnCdO has the least particle size among the samples of ZnCdO and rare earth doped ZnCdO. The morphological changes due to the addition of rare earth impurities have been found. Samples of La doped ZnCdO shows a pillar like morphology. The hexagonal structures are prominently seen in the SEM micrographs of the samples of ZnCdO. The UV-Visible spectral analyses show that the bandgap reduces when ZnCdO is doped with the rare earth impurities. The photoluminescence spectra show the broad spectrum in visible region exhibited by ZnO and a scanty UV emission. The UV emission of rare earth doped samples decreases due to the destruction in the crystal structure. The rare earth doped ZnCdO shows a small peak in green emission that decreases when rare earth impurities are doped. There is a uniform spectral response other than a small Gaussian like green peak. The overall analyses show that the samples can be used in optoelectronic applications to work in the visible region.
关键词： rare earth elements,structural properties,optical properties,UV-Visible spectral analyses,Cadmium,SEM micrographs,photoluminescence spectra,XRD analysis,Zinc oxide,solgel auto combustion,morphological properties
更新于2025-09-09 09:28:46