Optical characterization of ZnO nanoparticles and nanorods prepared by wet chemical technique at low temperature

Zinc Oxide nanoparticles and nanorods have been synthesized at an optimum temperature of 60°C using aqueous solution of zinc acetate and potassium hydroxide in methanol. Particle and rod like structures were obtained by merely varying the relative concentration of the reagents. A variety of techniques like UV-Vis absorption spectroscopy, X-ray diffraction (XRD), photoluminescence, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to carry out structural and spectroscopic characterizations. FTIR confirms the preparation of zinc oxide. XRD shows the formation of well crystalline nature and wurtzite structure of prepared zinc oxide samples. Grain sizes were also calculated using XRD data and found to be in 11-15nm range for all preparations. Presence of one-dimensional structures in the rod samples were confirmed by SEM images. Blue shift of the absorption peaks were found due to quantum confinement of excitons. Capping action of polyvinyl pyrrolidone (PVP) was also studied. Use of PVP leads to the decrement in aspect ratio of rods but provides spherical shaped nanostructures. Enhancement of UV-emission intensity with suppression of green emission intensity was observed by the use of PVP during preparation.

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