Effect of different O2/N2 flow rate on the size and yield of ZnO nanostructures

The effect of O 2 /N 2 flow rate on the size and yield of ZnO nanostructures was studied in a horizontal tube furnace via a thermal evaporation process. When the total flow rate of N 2 and O 2 is 400 sccm, the height/diameter ratio of the ZnO nanonails decreases with the increasing of O 2 flow rate and the yield firstly increases then decreases. X-ray diffraction patterns indicate all ZnO nanonails grow preferentially along the [0001] direction. Room-temperature photoluminescence spectra show that the intensity ratio of UV to green emission increases with increasing O 2 /N 2 flow rate. The CFD simulation results indicate that the controlled growth of ZnO nanonails can be achieved by adjusting the O 2 /N 2 flow rate. Nail-like ZnO nanostructures with different optical properties were prepared by adjusting the O 2 flow rate while the total flow rate of O 2 and N 2 keep at about 400 sccm. It is found that the O 2 flow rate has an important effect on the height/diameter ratio and yield of ZnO nanostructures.