The effects of annealing temperature on size, shape, structure and optical properties of synthesized zinc oxide nanoparticles by sol-gel methods

Abstract

Annealing affects zinc oxide nanoparticles (ZnONPs) in terms of size, structure, composition, shape, and optical properties. The aim of this study was to investigate the effects of annealing temperature on the particle size, structure, shape, chemical composition, and optical properties of synthesized ZnONPs by sol-gel method. The samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR), UV/Vis spectroscopy, and Photoluminescence. From XRD result, the synthesized ZnO has pure phase hexagonal wurtzite structure. Particle size, diffraction intensity, lattice parameters, bond length and spacing distance increase with the increase in annealing temperature, while strain size and full width at half maxima is decreased. Spherical images of synthesized ZnONPs were detected from SEM images. FT-IR peaks appeared in the region of 400-500cm−1 indicated the successful synthesizes of ZnONPs. The optical absorption of ZnONPs measured at different annealing temperatures showed that red shift as the annealing temperature was increased. The energy band-gap of synthesized ZnONPs was increased as annealing temperature increases. The emission peaks of synthesized nanoparticles are independent of the temperature while its emission intensity depends on the temperature.