Effect of Co Doping on Structural and Optical Properties of Zinc Oxide Nanoparticles Synthesized by Sol-Gel Method (original) (raw)
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Effect of Co doping on the physical properties of Co-doped ZnO nanoparticles
Journal of Materials Science: Materials in Electronics, 2017
Co-doped ZnO thin films Co +2 ions atomically substitute for Zn 2+ ions without altering ZnO wurzite structure [5]. During last few years, lot of research is concentrated on the synthesis and characterization of nanomaterials [11-14] due to their astonishing properties and expected applications in nano-devices. Keeping in view application of nanoparticles, in this project Co doped ZnO nanoparticles were synthesized. Although Co doped ZnO nanoparticles were already synthesized by chemical precipitation route [15], wet chemical route [16], sol-gel [17], hydrothermal route [18], auto-combustion route [19], solid state method [20]. In the present study, nano-particles of cobalt doped ZnO were fabricated by sol-gel route by varying the percentage of Co from 1 to 5 atom%. Hence the morphological, structural, magnetic and optical properties of cobalt-doped zinc oxide films were evaluated to observe the influence of doping on the properties of ZnO. 2 Experimental details Cobalt doped zinc oxide nano-particles have been synthesized. Starting materials were zinc acetate di-hydrate and cobalt nitrate hexa-hydrate. Zn sol [1] and Co sol [5] were prepared independently. Then both sols were mixed together and magnetically stirred the sol for 1 h at 35 °C. Then 10 ml iso-propanol (IPA) and 5 ml triethylamine (TEA) were added to the sol and magnetically stirred the sol for 5 h. Five sols with different percentage concentration of cobalt were obtained. Then the sols were centrifuged and nanoparticles were obtained. The nanoparticles were dried at 250 °C in oven and annealed for 2 h at 400 °C in furnace. The morphological properties were evaluated using the Scanning Electron Microscope (SEM Hitachi S-3400N).
Effect of Cobalt Doping on Physical Properties of ZnO Nanoparticles
2017
Nanocrystals of undoped and Cobalt doped Zinc Oxide nanoparticles (Zn1-x Cox O, where x = 0, 0.2 and 0.3M) were synthesized by simple solution route. Crystalline phases, optical absorption and band gap of Cobalt doped ZnO nanoparticles/Thin films were studied by X-ray diffraction and UV visible spectrophotometer. XRD results revealed that the sample product was crystalline with a hexagonal wurtzite phase. The particle size was determined by Scherrer method and W-H analysis. In case of Scherrer method and W-H anaylsis, the particle size of cobalt doped ZnO nanoparticles decreases with increase in concentration of cobalt (0, 0.2 and 0.3M) but the particle size of different concentration (0, 0.2 and 0.3M) of cobalt doped ZnO by using W-H analysis is greater than the particle size determined by using Scherrer method. The W-H analysis was used to study the individual contributions of crystallite size and lattice strain on the peak broadening of Co doped ZnO nanoparticles. Nanocrystalline...
Journal of Alloys and Compounds, 2011
Co doped ZnO nanoparticles were synthesized by sol-gel method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDAX), UV-Visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the formation of single phase structure of all samples which was further supported by FTIR data. With the increase in Co concentration from 0% to 5%, crystallite size was observed to vary from 27.1 to 21.3 nm. It suggests the prevention of crystal growth as a result of Co doping in ZnO. It was also evident from the absorption spectra that the absorbance tends to increase with the increase in dopant concentration. Optical band gap was found to increase slightly with the increase in Co content, confirming the size reduction as a result of Co doping.
Synthesis, structural and optical characterisation of cobalt and indium co-doped ZnO nanoparticles
2016
The undoped, 5% Co, In single doped and 5% In-Co double-doped ZnO nanoparticles were successfully prepared using sol-gel method. The structural and optical properties of the samples were investigated using XRD, UV-vis, TEM, EDS and Raman spectroscopy. There were no peaks associated with In or Co detected in the XRD patterns indicating that In and Co substituted for Zn ions in the ZnO wurtzite structure this was also confirmed by the EDS and Raman results. TEM results showed that the prepared ZnO nanoparticles were spherically shaped. Single doping reduced the grain size and the energy band gap of the ZnO nanoparticles while combinational doping reduced them even further.
Preparation and characterization of Co doped ZnO nanoparticles
Solid State Technology, 2020
We were prepared 5wt% Cobalt doped zinc oxide (Co-ZnO) nano crystals via hydrothermal technique at different temperatures of 70, 100, 130, 160 and 190oC. UV spectroscopy, XRD crystallography, EDS measurements, FE-SEM microscopy were used for characterizations and TEM microscopy. UV spectroscopy has shown absorbance peaks at: 370, 375, 377, 378 and 380 nm, and accordingly, values of energy gaps of: 3.35324, 3.30853, 3.29098, 3.28174, and 3.26447 eV; this is at the range of temperatures of: 70, 100, 130, 160 and 190oC, respectively. XRD crystallography has shown intense diffraction angles for the indices of: 100, 002, 101, 102, 112, 110, 103, 200, 112, 201, 311, 004 and 202 at a range of diffraction angles between10 to 80 degree. We experiential two extra indices at the diffraction angles of 44.56 o and 72.44o which have not been mentioned formerly by others, and we suppose this might indicates the formation of hexagonal crystallites with two extra planes. We measurements ...
Synthesis of Co-doped ZnO nanoparticles by sol–gel method and its characterization
Cobalt doped ZnO nanoparticles with different Co contents have been synthesized by a sol–gel processing technique. In our approach, the water for hydrolysis was slowly released by esterification reaction followed by a supercritical drying in ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by XRD, transmission electron microscopy, UV measurements, photoluminescence and superconducting quantum interference device. The structural properties showed that the obtained nanoparticles are in wurtzite single crystalline phase and no secondary phases were detected which indicated that Co substituted Zn ions. The energy band gap of the ZnO host matrix decreases gradually by increasing the doping concentration. The photoluminescence spectra exhibit intensive emission in the UV range. This emission presents a small shift to longer wavelengths and remarkable decreases in the intensity with increasing Co content. The Magnetic measurements at room temperature reveal diamagnetic behavior for the samples with lower doping concentrations; however, at higher Co content, we noted the presence of both paramagnetic and ferromagnetic behaviors.
Influences of Co doping on the structural and optical properties of ZnO nanostructured
Applied Physics A-materials Science & Processing, 2010
Pure and Co-doped ZnO nanostructured samples have been synthesized by a chemical route. We have studied the structural and optical properties of the samples by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), field-emission transmission electron microscope (FETEM), energy-dispersive X-ray (EDX) analysis and UV-VIS spectroscopy. The XRD patterns show that all the samples are hexagonal wurtzite structures. Changes in crystallite size due to mechanical activation were also determined from X-ray measurements. These results were correlated with changes in particle size followed by SEM and TEM. The average crystallite sizes obtained from XRD were between 20 to 25 nm. The TEM images showed the average particle size of undoped ZnO nanostructure was about 20 nm whereas the smallest average grain size at 3% Co was about 15 nm. Optical parameters such as absorption coefficient ( α), energy band gap ( E g ), the refractive index ( n), and dielectric constants ( σ) have been determined using different methods.
Transition metal (Co, Mn) co-doped ZnO nanoparticles: Effect on structural and optical properties
Journal of Alloys and Compounds, 2017
Pure ZnO and Co/Mn co-doped ZnO {Zn 0.98-x Co 0.02 Mn x O (0≤x≤0.06)} nanoparticles were synthesized by co-precipitation method. The structural, morphological and optical properties of prepared samples were explored in detail. Rietveld refinement of x-ray diffraction (XRD) data revealed the single phase, hexagonal wurtzite structure without any impurity phase. XRD and Fourier transform infra-red (FTIR) analysis confirmed the incorporation of Co/Mn ions at Zn site into host lattice structure. The morphology of samples was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The particle size from TEM results was corroborated well with XRD data. The absorption spectra showed the initial decrease in optical energy band gap for low Mn concentration. The optical energy band gap further increased with a higher Mn concentration in codoped ZnO samples. Photoluminescence (PL) spectra showed five emission peaks due to different defect states. The paper enhances the understanding of structural, optical properties of Co/Mn co-doped nanocrystals. This paves the path for its potential application in the optoelectronic devices e.g. solar cell.
Influence of doping Co to characterization of ZnO nanostructures
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2014
Cobalt doped zinc oxide nanoparticles were successfully synthesized using the hydrothermal method. The structure of these nanoparticles studied using x-ray diffraction clearly presented the existence of Co 3 O 4 phase in the 4% Co-doped ZnO samples. Field-emission electron scanning microscopy (FESEM) was used to examine the morphologies of products. Optical absorption measurements confirm the presence of a strong ultraviolet peak at 374 nm. The room temperature photoluminescence spectra investigated under the excitation at 325 nm by a neon laser exhibit both the ultraviolet and visible emission bands.
Optical and Structural Properties of Zinc Oxide Nanoparticles
2015
In the recent era zinc oxide nanoparticles attracted the researchers due to their unique properties and applications in optoelectronic devices. Zinc oxide nanoparticles are the semiconductor materials having band gap energy 3.37 eV and very large excitation binding energy (60meV) at room temperature. Also it is non-toxic, environmental friendly and transparent to visible range of spectrum. In the present investigation Zinc oxide nanoparticles were synthesized by sol gel method using zinc acetate and sodium hydroxide as precursors and de ionized (DI) water as solvent. The structure and morphology of prepared zinc oxide nanoparticles was studied using X-ray diffraction (XRD) spectroscopy and Scanning Electron Microscopy (SEM). UV visible spectrum shows the transparency of nanoparticles over entire visible range. The FTIR analysis confirms the formation of zinc oxide nanoparticles.