Role of sonic energy on growth morphology and optical properties of ZnO:S nanostructures

ZnO nanopowders doped with sulphur were prepared by sonochemical method. The input power of ultrasound was varied as 40%, 50% and 60% of the maximum power (375 W) in both continuous and pulsed mode. XRD results show the average size of the nanoparticles is the least for those prepared with 50% input power as well as the micro-strain. FESEM studies showed the formation of nanorods clubbed together to form flower like structure for these samples. In rest of the cases, no definite morphology was obtained. High resolution transmission electron microscopy (HRTEM) reveals the formation of nanorods oriented along c-axis for those samples prepared with 50% input power. No cavitation at 40% and excessive dissolution at 60% may lead to this type of morphology. Absorption studies showed high absorbance for sulphur doped samples but this was highest for the samples prepared with 60% input power.