Effects of annealing temperature on the properties of ZnO/SnO2 core/shell nanorod arrays

The effects of annealing temperature on the morphologies, structures and optical properties of ZnO/SnO2 core/shell nanorod arrays were investigated. It is found that the annealing of the samples in a muffle furnace at temperatures up to 900 °C transformed the nanorods into large particles and produced the Zn2SnO4 phase. The photoluminescence results showed that when the annealing temperature was increased up to 700 °C, the ratio of visible/ultraviolet emission increased and the center of the visible emission shifted from yellow to green. When the annealing temperature was 900 °C, the green emission made a red-shift, and a new broad peak appeared in the spectra. Possible emission mechanisms were also discussed.

► Annealing transformed the nanorods into large particles.
► Zn2SnO4 phase appeared for high annealing temperature.
► Increased annealing temperature led to increased visible emission and a band-shift in PL spectra.