Hydrothermal synthesis and optical property of scale- and spindle-like ZnO

In the present work, well-dispersed two new structures of scale- and spindle-like ZnO were successfully synthesized by using zinc nitrate hexahydrate as the starting material and also the low temperature hydrothermal process and any additional surfactant, organic solvents or catalytic agent. The ZnO structures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Optical property of the ZnO structures was investigated by room-temperature photoluminescence (PL) spectroscopy. The results revealed that ZnO powders have hexagonal (wurtzite-type) crystal structure and a large amount of well-dispersed ZnO scale- and spindle-like structures was formed. The thickness of scales was in the range 40–60 nm and the diameter of spindles was in the range 50–70 nm. Room-temperature PL spectra from the ZnO structures showed a weak UV emission peak at ∼382 nm and a very strong visible green emission at ∼530 nm, that was ascribed to the transition between VoZni and valence band.