Tetrapod-shaped ZnO crystals were synthesized by an oxidation process of Zn powder at temperatures over 930 8C 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 8C, tetrapod morphology was disappeared and changed to irregular
shape. Strong UVemission 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.
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