Fabrication and microstructure analysis on zinc oxide nanotubes

Well crystallized aligned zinc oxide nanoscale tubular structures have been fabricated via vapour phase growth on large area substrates. The ZnO nanotubes have regular polyhedral shapes, hollow cores with diameters of 30 100 nm, lengths over a few tens of micrometres and wall thicknesses of 4-10 nm. In morphology, the nanotubes were either straight or twisted with several straight parts. The microstructure of the tubular material was investigated in detail by using high-resolution transmission electron microscopy (HRTEM), Z-contrast imaging and compositional line profile analysis. The chemical composition of individual tubular structures was found to be stoichiometric ZnO using selected area energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. X-ray diffraction (XRD) and selected area electron diffraction results indicated that the ZnO nanotubes had wurtzite crystal structure. XRD analysis and HRTEM investigations indicated the ZnO nanotubes were grown along the [ 001] direction. The growth of the tubular ZnO nanostructures was found to be closely related to the hexagonal nature of the ZnO crystal and the peculiar growth conditions used.