Flower-like ZnO nano/microstructures have been synthesized by thermal treatment of Zn(NH3)(4)(2+) precursor in aqueous solvent, using ammonia as the structure directing agent. A number of techniques, including X-ray diffraction (XRD), field emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), thermal analysis, and photoluminescence (PL) were used to characterize the obtained ZnO structures. The photoluminescence (PL) measurements indicated that the as-synthesized ZnO structures showed UV (similar to 375 nm), blue (similar to 465 nm), and yellow (similar to 585 nm) emission bands when they were excited by a He-Gd laser using 320 nm as the excitation source. Furthermore, it has been interestingly found that the intensity of light emission at similar to 585 nm remarkably decreased when the obtained ZnO nanocrystals were annealed at 600 degrees C for 3 h in air. The reason might be the possible oxygen vacancies and interstitials in the sample decreased at high temperature. (C) 2007 Elsevier Ltd. All rights reserved.