Saturday, January 30, 2021

In this work, zinc oxide (ZnO) precursor was prepared by precipitation method from zinc nitrate and sodium carbonate in aqueous solutions. ZnO nanoparticles were obtained by annealing the precursor at different temperatures. The effect of the annealing temperature on the particle size and particle morphology of the ZnO nanoparticles were studied by XRD, SEM, EDX, BET, FTIR, and TG-DTA. The XRD results revealed pure wurtzite structured  ZnO nanoparticles. We have investigated the crystallite development in ZnO nanoparticles by X-ray peak profile analysis.  The Williamson–Hall analysis was employed to study the individual contributions of crystallite sizes and lattice strain (ε)  on the peak broadening of ZnO nanoparticles. The parameters including strain, stress, and energy density value were calculated for all the reflection peaks of X-ray diffraction corresponding to the wurtzite hexagonal phase of ZnO lying in the range 200–750 using the modified forms of Williamson–Hall. The results showed that the crystallite size estimated from Scherrer’s formula, Williamson–Hall models, and the particle size estimated from scanning electron microscopy analysis are very much inter-correlated. SEM images that the ZnO nanoparticles have particle-like morphology and having spherical morphology with a homogeneous size distribution, it also shows that ZnO nanoparticles aggregate severely with the rise in temperature leading to larger size particles. BET Surface area analysis, confirmed the formation of mesoporous ZnO with the surface area from 25.3641  to 8.7781  m2/g range as annealing temperature increased from 275 to 600°C, and mean diameter of 16.03 to 25.03 nm. FTIR confirmed the presence of Zn- O bond at 443.96 cm-1  which is due to the stretching vibration of Zn-O.