From Zn microspheres to hollow ZnO microspheres: A simple route to the growth of large scale metallic Zn microspheres and hollow ZnO microspheres

Large scale metallic Zn microspheres and hollow ZnO microspheres are synthesized by thermal evaporation and vapor transport by heating a ZnO/graphite mixture at 1000 degrees C. Firstly, metallic Zn microspheres are fabricated with diameters in the range of 1-10 mu m. The Zn microspheres are then annealed at 600 degrees C in air, which form hollow semiconducting ZnO microspheres. EDX and XRD spectra reveal that the oxidized material is indeed ZnO. Room temperature photoluminescence spectra of the oxidized material show a sharp peak at similar to 380 nm and a wider broad peak centered at similar to 490 nm. This growth mechanism is discussed and further investigated for other metallic and metal oxide microstructures. (c) 2006 Elsevier B.V. All rights reserved.