Control over crystallization is one of the most important strategies in modern materials science due to its potential to produce well-defined particles with unique structures in the nanometer and micrometer ranges. In present research article, we have developed a simple alcohothermal method to synthesize ZnO microcrystals on a large scale with a hexagonal wurtzite structure and different microstructures. Novel twinned cone-shaped, single cone-shaped, dumbbell-like, hamburger-like, hierarchically lapped and aligned hexagonal structures and tubular microstructures of ZnO crystals were obtained under different experimental conditions. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron diffraction, ultraviolet-visible (UV) absorption spectra and photoluminescence spectra have been employed to characterize these ZnO microcrystals. It has been shown that the reaction temperature and the quantity of Zn(NO_3)_2·6H_2O in the reaction system play an important role in determining the final morphologies of wurtzite ZnO crystals. The surfaces of hexagonal ZnO ice-cream cones are enclosed by polarized (0001) and {10l 1} planes. The growth mechanism of the hexagonal ice-cream cones is due to adsorbed alcohol lowering the surface energy of the polar surfaces. The tip of ice-cream cones is along the [0001] direction, the Zn polarized direction. On the other hand, novel twined ZnO microtubes with open end, growing along the [0001] direction, were also prepared in water and ethanol mixed solvent by surfactant-assisted hydrothermal method. Room temperature Photoluminescence results show that as-synthesized ZnO crystals display a narrow and sharp UV emission at 390 nm and a broad blue-green emission at above 466 nm excited by UV light, demonstrating excellent crystal quality of the products. The strategy demonstrated here can be extended to synthesize a wide range of other inorganic materials having fascinating microstructures and potential applications.
展开▼
