Transition metal (Co, Mn) co-doped ZnO nanoparticles: Effect on structural and optical properties (original) (raw)
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Applied Nanoscience, 2019
We have analysed the effect of co-doping Rare Earth (Ce) and Transition metal (Co) on optical properties in ZnO nanoparticles. We have prepared 1 at %, 2 at % and 3 at % Ce and Co co-doped ZnO nanoparticles annealed at 600 °C, 700 °C, and 800 °C temperatures by simple sol-gel method using ethanol as a solvent. The structural and morphological properties were characterized by XRD (X-ray Diffraction), RAMAN and SEM (Scanning Electron Microscopy), respectively. All the prepared samples were polycrystalline and wurtzite in structure, showing that Ce and Co have been successfully incorporated into the wurtzite crystal structure of ZnO. Particles were uniformly distributed and the calculated average crystallite size was in the range of 50-100 nm. There was no large shift in the XRD spectra. For optical properties PL (Photoluminescence) spectroscopic and UV-Visible spectroscopic techniques were used. We have obtained two sharp peaks in the PL spectra nearly at 510 and 612 nm. 510 nm emission may be due to trap-state, deep-level emission, whereas, 612 nm emission was due to either charge transfer (CT) transition between O −2 and Ce +4 ion. These two emission peaks were stable with respect to doping concentration upto 2%. The results show that this method produce perfectly co-doped ZnO nanoparticles having sharp emission spectra, so that we can use these materials in LEDs and photodetectors.
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.
Analysis of structural, optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals
Ceramics International, 2017
In this paper, the structural, optical and magnetic properties of pure ZnO and Fe/Co co-doped ZnO nanoparticles are presented. Rietveld refinement of XRD pattern revealed the single phase wurtzite structure for prepared samples. FTIR study confirmed the formation of tetrahedral coordination between zinc and oxygen ions. SEM and TEM techniques were used to examine the morphology of samples. The absorption spectra showed the decrease in optical energy band gap with Fe/Co codoping in ZnO. PL spectra demonstrated five peaks correspond to the ultraviolet region, violet, violetblue, blue-green and green in the visible region. Emission peak in the UV region is attributed to near band-edge excitonic emission. Other four emission peaks in PL spectra are related to different defect states. M-H curve showed room temperature ferromagnetic (RTFM) behaviour of doped ZnO sample. This paper enhances the understanding of structural, optical and magnetic properties of Fe/Co codoped ZnO nanocrystals for application in spintronics, solar cells, and ceramics.
Synthesis Structural and Optical Properties Of (Co, Al) co-doped ZnO Nano Particles
IOP Conference Series: Materials Science and Engineering
We prepared (Co, Al) co-doped ZnO nanostructures using the method chemical co-precipitation successfully, at room temperature using PEG (Poly ethylene glycol) as stabilizing agent. Samples are prepared with different concentrations by keeping aluminium at 5 mol percent constant and varying the concentration of cobalt from 1 to 5 mol percent. After the preparation all the samples are carefully subjected to characterizations such as XRD, SEM with EDS, TEM, PL and UV-VIS-NIR. XRD pattern shows that all the samples possess hexagonal wurtzite crystal structure having no secondary phases pertaining to Al or cobalt, which shows successful dissolution of the dopents. TEM results shows the accurate size of particles and is confirmed the XRD data. SEM images of all the samples shows that particles are in nearly spherical shape, EDS spectrum reveals that incorporation of cobalt and aluminum in host lattice. PL spectrum shows that all the samples containing two prominent peaks centered at 420 nm and 446 nm. UV-VIS-NIR spectra has shown three absorptions peaks in the range of wavelength 550 nm to 700 nm, which are ascribed as typical d-d transitions of cobalt ions.
Journal of Luminescence, 2012
Cobalt-doped Zinc sulfide (ZnS) nanoparticles were prepared by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (YH) as capping agent. The structural and optical properties of prepared cobalt-doped ZnS nanoparticles have been characterized. X-ray diffraction patterns and transmission electron microscope images reveal pure cubic ZnS phase with size of about 5-2 nm for all cobalt-doped ZnS nanoparticles. The lattice constant of the samples decreases slightly by the introduction of Co 2? The absorption edge of the ZnS:Co 2? nanoparticles is blue-shifted as compared with that of bulk ZnS, indicating the quantum confinement effect. The photoluminescence emission band exhibits a blue shift for Co-doped ZnS nanoparticles as compared to the ZnS nanoparticles.
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.
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.
In the present work Pure and Cobalt (Co) doped Zinc Oxide (ZnO) Nanoparticles were synthesized by Sol-gel method. The effect of Co doping on structural and optical properties of Nanoparticles were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopic characterization techniques. The XRD spectrum revealed the formation of Wurtzite structure of ZnO. The structural properties of nanoparticles including particle size and lattice strain were calculated from XRD data. SEM shows the morphology of Na-noparticles. The presence of functional groups was analyzed from FTIR spectra. The properties of Cobalt doped zinc oxide nanoparticles prepared through simple cost effective, Sol-gel method can be used in optoelectronics and thermally stable devices.
Structural and Optical Properties of Mn Doped ZnO Nanoparticles
Nanostructured semiconductors are of great interest due to their fascinating physiochemical properties, contrary to their bulk counterparts. Zinc oxide is a potential material for spintronic devices. That can also be used for fabrication of gas sensors, piezoelectric transducers and solar cell windows. We have synthesized the Mn doped zinc oxide nanoparticles using sol gel technique for Mn concentration x = 0.01, 0.02, 0.03 and 0.05. The samples are characterized with powder x-ray diffraction for phase purity. All the samples are found in single phase with wurtzite lattice structure. The UV/V spectra of nanoparticles indicate a decrease in the band gap from 3.08 eV to 3.05 eV with 1 % change in Mn concentration. But further increase in Mn concentration results in the increase of band gap to 3.12 eV. The Photoluminescence spectra are recorded in order to observe the effect of Mn doping on emission bands of ZnO.