Large-scale production of ZnO nanoparticles by high energy ball milling

We present a structural, microstructural, and optical study on ZnO nanoparticles produced in large quantities (600 kg) by high energy ball milling. Dynamic light scattering analysis indicated a decrease in the particle size from 416.60 to 33.27 nm for the sample without and with the maximum energy of milling performed, respectively. X-ray diffraction results revealed a single phase corresponding to a hexagonal crystal structure as well as a broadening of the diffraction peaks in association with the decreasing crystal size. Diffuse reflectance spectroscopy study revealed a decrease in the reflectance due to the particle size reduction, and a contraction of the band gap energy from 3.244 to 3.112 eV. A correlation was found between crystal size and band gap. Brunauer-Emmett-Teller analysis revealed that the surface area increased almost threefold (from 4.4000 to 12.0031 m2 g-1) with increasing milling energy. Additionally, scanning electron microscopy observations showed an increased homogeneity in the particle size distribution with increasing milling energy.