Micrometer-sized spherical ZnO ultrafine powder was prepared by polyvinyl alcohol gel method. Zinc acetate was used as starting material

polar polymer polyvinyl alcohol with long chain was used as grids localization and lattice reagent to control nucleation and crystal growth via ionic complexation between the hydroxy groups and Zn

2+

ions. The products were obtained by changing thermal treatment under controlling rise rate. The as-prepared ZnO powder was characterized by X-ray diffraction (XRD)

scanning electron micro-scopy (SEM) and photoluminescence (PL) spectra. The analytical results of SEM and XRD indicate that the concentrations of the PVA solution

sintering temperature are the factors influencing the preparation. It is found that the uniform spherical ZnO with diameter about 1~3 μm are obtained under the conditions of a PVA concentration of 5% and sintering temperature of 500℃ at which most of polymer are removed after 3 h.The PL spectra of these samples include two blue emission peaks

centered at 407 nm which is attributed to the zinc vacancies and 468 nm which is due to the transition of electrons from the level of the ionized oxygen vacancies to the valence band at room temperature when excited with 325 nm light. The ultraviolet emission peak located at 385 nm which originates from the interband transition of electrons has been observed at certain temperature. It is found that the intensities of these peaks vary with annealing temperature. With increasing the heat treatment temperature

the blue emission peak at 407 nm gradually disappears. The intensities of ultraviolet emission peaks are sharply enhanced and approach a maximum value for the sample prepared at 500℃

then it decreases as the annealing temperature increase up to 600℃.