Structure-Property Correlations in ZnO Tetrapods and Spheres prepared by Chemical Vapour Synthesis

We present experimental results on the synthesis and characterization of ZnO nanorods, tetrapods and nanospheres prepared by the gas phase oxidation of zinc vapor followed by the collection of the oxide particles in an aerosol. Spherical nanoparticles or fine nanorods of ZnO consisting principally of tetra pod like structures are obtained selectively depending on the process parameters. Intermediate structures can also be synthesized. Transmission electron microscopy of the particles and rods shows that these are single crystals with diameters in the 5-50nm range. We find that the tetrapods have high absorption in the UV and nearly 100% reflectivity in the visible. UV absorption coefficients for suspensions of tetrapods are found to be substantially higher (x10) than for commercial nanocrystalline powders.