The Effect of Growth Time on the Morphology of ZnO Nanorods by Hydrothermal Method

Abstract

ZnO nanorod arrays were synthesized by hydrothermal method under different growth times. The effect of growth time on nanorods morphology was investigated systematically. Results illustrate that ZnO nanorods with hexagonal wurtzite structure grow vertically on the Si substrates. The length of the ZnO nanorods increases with increasing growth time. In our experiments, quenching stage plays a key role in forming the tips of nanorods. With growth time no more than 1h, the solution is in a continuous heating state and doesn’t reach the set temperature 180oC. Therefore, longer growth time means higher solution temperature which in turn increases cooling rate during quenching stage, as a consequence, to a smaller mean crystal size in the nanorods tips.