Thermal annealing behavior of SnO2-sheathed TeO2 nanowires

초록

SnO2-sheathed TeO2 one-dimensional (1D) nanostructures were synthesized by thermal evaporation of Te powders and then atomic layer deposition of SnO2. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the TeO2 cores are of a single crystal nature with a monoclinic structure while the SnO2 shells are amorphous. Room-temperature photoluminescence (PL) spectra of the TeO2 nanowires show a broad yellowish green emission centered at around 550 nm. The emission is slightly decreased in intensity by SnO2 coating, but it is significantly increased by thermal annealing in an oxygen atmosphere. The emission peak is also slightly red-shifted by oxygen annealing. Energy-dispersive X-ray spectroscopy (EDXS) analysis results reveal that the increase in the emission intensity is attributed to the increase in the concentration of the Te vacancies in the cores by the inflow of oxygen during oxygen annealing. On the other hand, annealing in a reducing atmosphere leads to a small increase in the PL emission intensity and a red shift of the emission to ~ 600 nm.