Synthesis of ZnO nanorod and the annealing effect on its photoluminescence property

Single crystal ZnO nanorod has been prepared by hydrothermal method. Optical properties of the nanorod were studied by annealing the nanorod at different ambiences. The annealed and unannealed samples were characterized by X-ray diffraction (XRD), tansmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), UV–Vis absorption (UV) spectroscopy and photoluminescence (PL) spectroscopy. The photoluminescence spectra under excitation 325 nm for the as-prepared ZnO nanorod show three bands: UV emission at 386 nm, blue emission at 468  and orange emission at 640 nm. By annealing the crystals in ammonia gas at 600 °C, the PL spectra shows obvious UV near band-edge emission at 386 nm and a green emission at 510 nm. While annealing the crystals in air, the orange emission was greatly enhanced.