Abstract
ZnO nanoparticles with hexagonal wurtzite structure were synthesized by using microwave irradiation. The effects of annealing temperatures on the structural, surface morphology and dielectric properties of annealed ZnO nanoparticles were investigated by XRD, FTIR spectra, and dielectric measurements. The XRD reveals the presence of hexagonal wurtzite structure of ZnO average grain size 25.7-36.4 nm. The spectra obtained from FTIR containing two intense absorption bands are attributed to bending and stretching vibrations absorption of Zn-O bond for all annealed ZnO nanoparticles. Dielectric properties of annealed ZnO nanoparticles at different temperatures were studied with respect to frequency. The dielectric measurements reveal that the dielectric response of ZnO nanoparticles is significantly enhanced, especially in the low-frequency range. In conclusion, both the rotation direction polarization and space charge polarization due to a large amount of oxygen vacancies and nano-size effects are responsible for the enhancement of the dielectric properties of ZnO nanoparticles.