ZnO Micro/Nanocrystals Synthesized by Thermal Evaporation Method using Mn Powder as the Reducing Agent

Zinc oxide(ZnO) micro/nanocrystals are grown via thermal evaporation of ZnO powder mixed with Mn powder, which is used as a reducing agent. The ZnO/Mn powder mixture produces ZnO micro/nanocrystals with diverse morphologies such as rods, wires, belts, and spherical shapes. Rod-shaped ZnO micro/nanocrystals, which have an average diameter of 360 nm and an average length of about 12 mu m, are fabricated at a temperature as low as 800 degrees C due to the reducibility of Mn. Wire- and belt-like ZnO micro/nanocrystals with length of 3 mu m are formed at 900 degrees C and 1,000 degrees C. When the growth temperature is 1,100 degrees C, spherical shaped ZnO crystals having a diameter of 150 nm are synthesized. X-ray diffraction patterns reveal that ZnO had hexagonal wurtzite crystal structure. A strong ultraviolet emission peak and a weak visible emission band are observed in the cathodoluminescence spectra of the rod- and wire-shaped ZnO crystals, while visible emission is detected for the spherical shaped ZnO crystals.