Synthesis and characterization of ZnO nanostructures

Nanocrystalline ZnO of various shapes was obtained without the use of catalysts by dry oxidation of Zn. Scanning Electron Microscopy results showed that the oxidation of zinc single crystals at temperatures below the melting point of Zn lead to the formation of a zinc oxide layer of flakes-type structure covering the surface of the sample. Above the melting point, long nanofibers were formed. The density and the length of these nanofibers increase as the temperature and the oxidation time increase. These results underline the importance of the role of the ZnO vapor pressure on the growth of nanocrystalline zinc oxide. X-ray Photoelectron Spectroscopy results confirmed the formation of oxide layer within a few minutes of heatinghe exposure of a Pt substrate to zinc foil during oxidation treatment led to the formation of long entangled nanofibers in the region of the substrate exposed directly to the zinc foil. High quality ZnO nanocrystals of hexagonal shape were obtained on the region of the substrate covered by a mica sheet. X-ray Diffraction results showed that the lattice parameters of the nanofibers are 1 % smaller than those of microcrystalline ZnO. Experiments are in progress to grow unidirectional nanofibers under high electric field.