Effects of annealing temperature on some structural and optical properties of ZnO nanoparticles prepared by a modified sol–gel combustion method

Abstract

Abstract<br><br>Plate-shaped zinc oxide nanoparticles (ZnO-NPs) were successfully synthesized by a modified sol–gel combustion method. Zinc acetate, pure<br><br>water and isopropanol were used as the starting materials. Acetic acid, diethanolamine and nitric acid were used as the polymerization agent,<br><br>complexing agent and fuel, respectively. The precursors were formed by mixing aqueous solutions of zinc acetate, acetic acid and diethanolamine.<br><br>Nitric acid was used to dry the produced gel. The resulting xerogel was annealed at 600 8C, 650 8C and 750 8C for 1 h. The synthesized ZnO-NPs<br><br>were characterized by X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA) and high-magnification transmission electron<br><br>microscopy (TEM). The XRD results revealed that the samples produced were crystalline with a hexagonal wurtzite phase. The TEM results<br><br>showed single-crystal ZnO-NPs with nearly hexagonal plate shapes. The optical properties of the ZnO-NPs were studied by UV–visible and<br><br>Fourier-transform infrared spectroscopy (FTIR). The UV–vis absorption spectra of the ZnO-NPs indicated absorption peaks in the UV region,<br><br>which were attributed to the band gap of the ZnO-NPs. The results of the FTIR and UV–vis studies showed that the optical properties of the ZnONPs<br><br>depended on the annealing temperature.