Varying the microstructural properties of ZnO particles using different synthesis routes (original) (raw)
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Development of ZnO microstructures produced by rapid hydrolysis of zinc acetylacetonate
Ceramics International, 2014
ZnO particles were produced combining the rapid hydrolysis of zinc acetylacetonate and autoclaving the precipitation systems at 220 o C. The possible influence of cetyltrimethylammonium bromide (CTAB) on the ZnO microstructure was also investigated. ZnO particles showed certain differences in their microstructure, although all of them were based on hexagonal symmetry (wurtzitetype crystal structure). The presence of hollow ZnO particles was also shown. All these particles showed their substructure, consisting of nanosize ZnO particles (crystallites) which built stable hexagons. The presence of lamellar substructure in the formation of hexagonal ZnO pyramids was also noticed. The corresponding mechanism included (a) rapid hydrolysis of zinc acetylacetonate yielding a ZnO phase, (b) formation of Zn(NH 3 ) 4 2+ complexes and partial dissolution of the ZnO phase, (c) decomposition of Zn(NH 3 ) 4 2+ complexes at autoclaving temperature, and (d) competitive reaction of Zn(OH) 2 formation with transformation to ZnO.
Journal of Ceramic Science and Technology
A low-temperature hydrothermal method was used to prepare ZnO nano-microparticles using surfactant-free solutions. The effect of the alkali concentration (Zn 2+ /OH-= 1:1, 1:2, 1:4 and 1:8) and reaction time (1, 2 and 3 hours) on the morphology of the ZnO was studied. The structure and the morphology of the ZnO obtained were investigated by means of XRD and SEM techniques, respectively. The results revealed that the solution basicity and reaction time were important factors affecting the morphology. With an increase in the reaction time, the crystallinity of the phases formed was enhanced. At a low alkali concentration, i.e. 1:1, a ZnO hexagonal prism-like structure with a crystal size of 300 nm-1.5 lm and Zn(OH) 2 amorphous phase were formed. With a further increase to Zn 2+ /OH-=1:2, some nanorods and flakes appeared beside the ZnO nanoparticles. When the ratio reached Zn 2+ /OH-= 1:4, different morphologies such as nanorods, slices and nanoflakes were obtained. At Zn 2+ /OH-= 1:8, the morphology changed into microflowers as the major structure with some nanoparticles and nanosheets as the minor structure.
European Journal of Inorganic Chemistry, 2009
A facile and reproducible route to nanostructured colloidal ZnO nanoparticles was developed by controlled hydrolysis and condensation of zinc acetylacetonate in alkaline conditions. By reaction of an ethanolic solution of Zn(acac) 2 with NaOH in a 1:2 molar ratio, after reflux, ZnO spherical nanoparticles were obtained that displayed a homogeneous size distribution; particle diameters ranged from 6 to 10 nm, as evidenced by transmission electron microscopy (TEM) analysis. The same reaction was carried out also in water, glycerol and 1,2-propanediol, to investigate the effect of the solvent viscosity and dielectric constant on the final features of the obtained material. Irrespective of the nature of the solvent, X-ray diffraction (XRD) analysis shows the formation of hexagonal ZnO, whereas the presence of residual unreacted Zn(acac) 2 could be ruled out. Indeed, different particle sizes and very different morphologies were obtained. Also the reflux step was shown to be a key factor in avoiding the fast precipitation of a floc and achieving a pure compound, which
Synthesis of ZnO nanopowder via an aqueous acetate–citrate gelation method
Materials Research Bulletin, 2002
The synthesis of nanoparticulate ZnO via an aqueous carboxylate gelation route is presented. Starting from a solution of zinc acetate with citric acid as a complexing agent, a solid glassy gel is obtained after drying that is converted into a ®ne powder by calcination. It is found that a very homogeneous precursor is indispensable when preparing very ®ne particles with a narrow size distribution. Cryo-transmission electron microscopy (Cryo-TEM) investigation is used as a feedback tool to prevent early precipitation during gelation. Study of the thermal decomposition of the gel shows that ZnO is formed before the ®nal decomposition step takes place. After removing the organic backbone, very small oxide particles are found. The in¯uence of the thermal treatment parameters on the particle size is investigated and a particle growth process is found. By a proper adjustment of the ®nal calcination temperature in dry air, the mean particle size can be controlled between $11 and 175 nm. It was also seen that even in inert atmosphere, ZnO is formed and that particle morphology is greatly in¯uenced by the calcination atmosphere. #
Synthesis and characterization of ZnO nanostructures with varying morphology
Bulletin of Materials Science, 2017
Uniform fine particles of zinc oxide were prepared in three different morphologies and sizes by the controlled precipitation process from aqueous solutions of zinc nitrate in the presence of ethylene glycol. Ammonium hydroxide solution was used as the precipitant. Composition of the reactant solution, pH and temperature significantly affected the particle uniformity with respect to shape and size. Uniformity in the particles morphological feature was achieved under a narrow set of experimental conditions. pH of the reactant solutions and isoelectric point of zinc oxide were considered the master variables, controlling the particle size. One of the batch of the as-prepared zinc oxide particles was calcined at 750 • C, which increased its crystallinity, changed its various lattice parameters, Zn-O bond length and preferred orientation of the crystal hkl planes. Calcination had little effect on the original morphology of the zinc oxide particles.
Synthesis and microstructural properties of ZnO nanoparticles prepared by precipitation method
Renewable Energy, 2013
In this work, zinc oxide (ZnO) precursor was prepared by precipitation method from zinc nitrate and ammonium carbonate in aqueous solutions. ZnO nanoparticles were synthesized by annealing the precursor at different temperatures. The effect of the annealing temperature on the particle size and photo-luminescence (PL) properties of the synthesized ZnO nanoparticles were studied by XRD, SEM, BET, TG-DTA and PL measurements. The XRD results indicated that the synthesized ZnO nanoparticles had the pure wurtzite structure. It is found that with increasing the annealing temperature the crystalinity and particle size increases as well as the lattice parameters approaches to those of the XRD standard. The studies of the aggregation of the samples were also carried out by comparing SEM micrographs with specific surface measurements and XRD results. Finally, the room temperature PL spectra show UV emission peak in the range of 378.50e379.80 nm, which is close to the bulk ZnO.
Preparation and Characterisation of ZnO Nanoparticles
2016
In this work, spherically shaped ZnO nanoparticles of size around 100 nm have been synthesized by sol gel process using zinc acetate dehydrate and sodium hydroxide as starting materials at room temperature. Surface morphology and microstructural characterization of the particles are carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), particle size analysis by dynamic light scattering (DLS), grain size and crystal structure using X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The X-ray diffraction results indicated that the synthesized ZnO particles are of single phase and the average particle sizes were about 100 nm. The synthesized nanoparticles could be applied in the treatment of industrial waste water.
2021
Due to its interesting physical and chemical properties, zinc oxide (ZnO) is considered one of the front runners of numerous metal oxide semiconductors. In this paper, ZnO nanostructure are synthesised by hydrothermal method with trisodium citrate (TC) as the emulsfying agent. The mean diameetr of ZnO nanostructure are observed with increment of reaction temperature. The mean size results into no change to mean diameter upon increment of reaction temperature but the cumulative frequencies of size distribution showing ZnO nanostructure synthesised in higher temperature to have narrower size distribution. The addition of TC also results into much smaller ZnO nanostructure with mean diameter 8nm
Applied Mechanics and Materials, 2011
In this work, the precursors zinc nitrate hexahydrate and zinc chloride were used to synthesize zinc oxide (ZnO) nanocrystals, applying a simple solochemical technique. ZnO rod-like nanostructures were successfully obtained by chemical reaction between NaOH and zinc nitrate hexahydrate at 90 °C. The sample formed by chemical reaction between NaOH and zinc chloride at 90 °C showed the ZnO phase mixed with the Zn5(OH)8Cl2•H2O phase. Only after thermal treatment at 500 °C for 3 hours, the conversion of Zn5(OH)8Cl2•H2O in ZnO was achieved. The samples prepared with different precursors were characterized by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. Rietveld analysis to the X-ray diffraction data indicated that ZnO nanocrystals obtained have hexagonal wurtzite structure and nanometric-sized crystallites.