ZnO micro/nanocrystals synthesized via a thermal evaporation of Al–Zn mixtures

Abstract

ZnO micro/nanocrystals with different morphologies were synthesized through thermal evaporation of Al–Zn mixtures under air atmosphere. The Al–Zn mixtures were put into alumina crucibles and then inserted into an electric furnace. The effect of synthesis temperature and time on the morphology of ZnO crystals was investigated. At temperatures below 900°C, no ZnO crystals were synthesized. When the temperature was 1000°C, ZnO crystals with a hexagonal pillar shape were found. With the increase in the temperature from 1000 to 1100°C, the morphology of the crystals changed to wire and granular shapes. As the synthesis time increased at 1000°C, tetrapod-shaped ZnO crystals started to be formed. As a result, the synthesis temperature and time were key factors in the morphological control of ZnO crystals. Because no catalyst particles were observed at the tips of the micro/nanocrystals, it is suggested that the ZnO crystals were grown via a vapor–solid mechanism.