TeO2-core/SnO2-sheath nanowires

TeO2/SnO2 nanowires were synthesized by a two-step process comprising the thermal evaporation of Te powders and the atomic layer deposition of SnO2. Transmission electron microscopy and X-ray diffraction analysis results indicate that the cores and shells of the coaxial nanowires are polycrystalline monoclinic-type TeO2 and polycrystalline simple orthorhombic-type SnO2, respectively, although the SnO2 shells are amorphous before annealing. Photoluminescence measurement shows that the TeO2 nanowires have a blue emission band centered at approximately 460 nm. The blue emission of the TeO2 nanowires is slightly enhanced in intensity by sheathing them with SnO2 and further enhanced by thermal annealing in a reducing atmosphere. Energy-dispersive X-ray spectroscopy concentration profiles suggest that the enhancement in the blue emission is attributed to the increases in both the O vacancy and Sn interstitial concentrations in the cores during the annealing process.