Quantum Size Effect in ZnO Nanoparticles via Mechanical Milling

ZnO nanocrystals were successfully produced by mechanical milling. It is shown that mechanical milling is very effective and simple to produce ZnO nanoparticles with the possibility of obtaining large quantities of materials. Size effects in ZnO nanoparticles were probed by XRD and UV-vis and photoluminescence (PL) spectroscopy. Absorption due to free electron was clearly observed, whereas strong PL lines were recorded in the UV and blue region. The absorbance and photoluminescence were found to increase with reduction in particle size. Blueshift of excitonic and emission peaks was observed as a consequence of the size quantization effect. Formation of pure ZnO phase was confirmed from XRD pattern and the optical spectroscopy.