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The undoping ZnO emitting films were deposited on Si substrates by dc reactive sputtering. There are two peaks of photoluminescence ͑PL͒, centered at 3.18 eV ͑ultraviolet͒, and at 2.38 eV ͑green͒, to be observed in the samples. We investigated the dependence of PL spectra on annealing temperature and annealing atmosphere. According to the calculation of defect levels and the relationship between PL spectra and annealing conditions, we supposed that the green emission of ZnO films corresponds to the local level composed of the antisite defect O Zn .

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The cathodoluminescence o f ZnO films deposited on Si substrates by reactive dc sputtering is investigated. Apart from the characteristic green emission band (522nm) o f ZnO, an ultraviolet (392nm) band and a blue (430-460 n m ) band have been observed. The x-ray diffraction and cathodoluminescent spectra reveal the dependences o f the luminescence on the preparation conditions and crystallinity of the ZnO films.

Three-dimensional (3D) flower-like hierarchicalβ-Ni(OH)2hollow architectures were synthesized by a facile hydrothermal route. The as-obtained products were well characterized by XRD, SEM, TEM (HRTEM), SAED, and DSC-TGA. It was shown that the 3D flower-like hierarchicalβ-Ni(OH)2hollow architectures with a diameter of several micrometers are assembled from nanosheets with a thickness of 10–20 nm and a width of 0.5–2.5 μm. A rational mechanism of formation was proposed on the basis of a range of contrasting experiments. 3D flower-like hierarchical NiO hollow architectures with porous structure were obtained after thermal decomposition at appropriate temperatures. UV–Vis spectra reveal that the band gap of the as-synthesized NiO samples was about 3.57 eV, exhibiting obviously red shift compared with the bulk counterpart.

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In this work, a facile route using a simple solvothermal reaction to synthesize 3D porous flowerlike hierarchical nanostructures (HNs) of α-Fe(2)O(3) without employing templates or matrices for self-assembly is presented. The morphology and compositional characteristics of the 3D HNs were investigated by various techniques. The 3D HNs composed of 2D nanopetals, were intercrossed with each other and constructed from nanobricks with a length of about 100 nm and a diameter of about 30 nm. Influencing factors such as the reaction time, dosage of reactants and the solvents are systematically investigated. A possible formation mechanism for the 3D HNs is proposed. On the basis of characterization results, the growth of such 3D HNs has been proposed as a self-assembly followed by Ostwald ripening process. The specific surface area of the 3D HNs also was investigated by using nitrogen adsorption and desorption isotherms. The as-prepared α-Fe(2)O(3) HNs have a comparatively large Brunauer-Emmett-Teller (BET) surface area of about 52.51 m(2) g(-1). The photocatalytic properties of the as-obtained α-Fe(2)O(3) 3D HNs are systematically investigated, which was evaluated by the degradation of RhB dye under ultraviolet light irradiation. The result shows that photocatalytic activity is greatly affected by the hierarchical and porous structure.

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