Characterization of mechanothermally processed nanostructured ZnO

In this paper, the Taguchi method with an L9(34) orthogonal array was used as experimental design to determine the optimum conditions for preparing ZnO nanoparticles via a mechanothermal route. ZnSO4·H2O and Na2CO3 were used as starting materials. The effects of milling time, Na2CO3/ZnSO4·H2O molar ratio, and ball-to-powder mass ratio (BPR) on the bandgap (E g) of ZnO nanoparticles were investigated. The ranges of the investigated experimental conditions were 5–15 h for the milling time (t), 1.0–1.2 for the Na2CO3/ZnSO4·H2O molar ratio (M), and 10–30 for BPR. The milling time and BPR exhibited significant effects; an increase in milling time reduced the bandgap. The optimum conditions from this study were t 3 = 15 h, M 1 = 1, and BPR2 = 20. Only two significant factors (t 3, 15 h; BPR2, 20) were used to estimate the performance at the optimum conditions. The calculated bandgap was 3.12 eV, in reasonable agreement with the experimental results obtained under the optimized conditions.