Role of Ag ions on the structural evolution of nano ZnO clusters synthesized through ultrasonication and their optical properties

ZnO powder doped with 0.84 at wt.% of silver has been synthesized through continuous and pulsed mode sonication method. The particle size was found to be 57(±1) nm and 44(±1) nm for continuous and pulsed mode powder, respectively. Contraction along ‘c’ axis has been observed for Ag doped powders. The surface area measured for pulsed mode powder was found to be twice that of continuous mode powder. Photoluminescence spectra of pulsed mode ZnO:Ag powder show new emission band at 608 nm. This has been attributed to silver atoms sitting on the surface of ZnO nano rods. Structure of the nano rods observed in both the samples was found to be different and this has been attributed to the presence of silver on the surface of the nano rods. The structural evolution during the process of sonication has been explained in the light of Ag ion reduction in the local high concentration region during ultrasonication.