Voids, nanochannels and formation of nanotubes with mobile Sn fillings in Sn doped ZnOnanorods

Abstract

ZnO nanorods containing different hollow structures have been grownby a thermal evaporation–deposition method with a mixture of ZnS andSnO2 powders as precursor. Transmission electron microscopy shows rods with rows of voidsas well as rods with empty channels along the growth axis. The presence of Snnanoprecipitates associated with the empty regions indicates, in addition, that these aregenerated by diffusion processes during growth, probably due to an inhomogeneousdistribution of Sn. The mechanism of forming voids and precipitates appears to be basedon diffusion processes similar to the Kirkendall effect, which can lead to void formation atinterfaces of bulk materials or in core–shell nanostructures. In some cases the nanorods areZnO tubes partially filled with Sn that has been found to melt and expand by heating thenanotubes under the microscope electron beam. Such metal–semiconductor nanostructureshave potential applications as thermal nanosensors or as electrical nanocomponents.