Synthesis and cathodoluminescence of ZnO tetrapods prepared by a simple oxidation of Zn powder in air atmosphere

Tetrapod-shaped ZnO crystals were synthesized by an oxidation process of Zn powder at temperatures over 930 °C in air. The ZnO crystals were formed in an alumina crucible in which metallic Zn powder was put. X-ray diffraction patterns revealed that the tetrapods were ZnO with wurtzite structure. Any impurities including Zn were not detected, indicating that the ZnO crystals were of high quality. As the oxidation temperature increased, the size of tetrapods was getting larger and longer. However at 1100 °C, tetrapod morphology was disappeared and changed to irregular shape. Strong UV emission at 380 nm was observed in the CL spectra taken for the ZnO tetrapods. The increase in the intensity of green emission at 510 nm was also observed with increased oxidation temperature.