Change in the morphology of ZnO crystals by thermal evaporation method using a mixture of ZnS and graphite

One dimensional rod-shaped and two dimensional twin-crystal shaped ZnO crystals were fabricated by thermal evaporation of a mixture of ZnS and graphite powders in air at atmospheric pressure. Twin-crystal shaped ZnO crystals were formed at 1050 degrees C, while rod-shaped ZnO crystals were synthesized at 1150 degrees C. The morphology of ZnO crystals was drastically changed according to the growth temperature. It is particularly interesting that two hexagonal plates formed a twin crystal, in which hexagonal shaped ZnO plates were symmetrically grown on both sides of a mirror-like plane. The twin crystal looked like a yo-yo. X-ray diffraction analysis showed that the rod and twin-crystal shaped ZnO crystals exhibited a wurtzite crystallographic structure. A strong green emission peak at 500nm was observed in the cathodoluminescence spectra of the ZnO crystals at room temperature. (C) 2017 The Ceramic Society of Japan. All rights reserved.