Synthesis of ZnO nanorods by microwave irradiation of precursor solution and study of their process parameters

Abstract

Zinc oxide (ZnO) nanorods in the form of hexagonal prismatic shape have been successfully synthesized by a simple one step microwave assisted irradiation process using a customized domestic microwave oven. The effects of different process parameters such as microwave power, precursor reagents, synthesis time, precursor concentration etc. have been studied. The morphological, structural and optical properties of the ZnO nanorods are studied using scanning electron microscopy, powder X-ray diffraction and UV-Visible spectroscopies. ZnO nanorods with the smallest diameter of 300 nm has been synthesized using zinc nitrate precursor. The average diameter increases from 300 to 500 nm and the average length varies from 1.8 to 3.5 m with the increase in precursor concentration and synthesis time. The best length to diameter ratio of the synthesized ZnO nanorods was obtained with an optimum concentration of 15 mM and synthesis time of 20 min using the customized system with basic precursor solution. All the samples have strong absorption in the UV region and the band gap values varies between 3.28 to 3.30 eV, very near to the standard value of 3.40 eV for ZnO at room temperature. XRD spectra confirms the hexagonal wurtzite structure of the ZnO nanorods and EDAX study confirms their purity. The nanorods has a higher dielectric constant value at room temperature in the lower frequency region, which decreases with increasing frequency.