Microstructure and optical properties of ZnO nanoparticles prepared by a simple method

In this investigation, ZnO nanoparticles were prepared by a simple and rapid method. This method is based on the short time solid state milling and calcinations of zinc acetate and citric acid powders. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, photoluminescence and UV–vis spectroscopy. It was shown that the calcination temperature significantly affected the particle size and optical properties of the synthesized ZnO nanoparticles. Calculation based on the XRD data shows that the average sizes of ZnO particles are in agreement with those from TEM images and the size of the particles increases on increasing the calcination temperature. Also the band gap of samples decreased from 3.29 to 3.23 eV on increasing the calcination temperature from 350 to 600 °C. Photoluminescence analyses show that many defects such as interstitial zinc, zinc vacancy and oxygen vacancy are responsible for the observed optical properties.