2017 Volume 58 Issue 8 Pages 1203-1206
ZnO microrods with inverted cone shape and nail-like shape were formed by thermal evaporation of ZnS powder and ZnS/Zn mixture under air atmosphere. No catalysts and substrates were used. When ZnS powder was used as a source material, ZnO crystals had an inverted hexagonal cone shape, where the diameter of the microrods increased gradually from about 10 μm at the bottom to 35 μm at the top. When a mixture of ZnS and Zn powders was used as a source material, the diameters of the ZnO microrods increased significantly up to 40～80 μm at the top, which makes the ZnO microrods a nail-like shape. X-ray diffraction patterns showed that all the ZnO microrods had a wurtzite crystallographic structure. Two emission peaks were observed in the cathodoluminescence spectra at room temperature. One was a peak at around 380 nm (ultraviolet) and the other was a peak at 510 nm (green). The high intensity ratio of ultraviolet emission to green emission was obtained for the nail-shaped ZnO microrods, indicating the high crystalline quality of the ZnO microrods.