ZnO nanorods, nanotubes and nanorings: controlled synthesis and structural properties.

Controlled synthesis of ZnO nanorods (ZNRDs), nanotubes (ZNTs) and nanorings (ZNRs) has been carried out by a two-step sonochemical/chemical process at room temperature without any catalyst, template or seed layer. The crystallinity, structure and morphology of ZNRDs, ZNRs and ZNTs were examined by X-ray diffraction (XRD) analysis, scanning electron micrographs (SEM), high resolution transmission electron microscope (HR-TEM) and selected area electron diffraction (SAED). The as-prepared ZnO nanostructures were single crystalline with hexagonal cross-section and uniform size.