Fabrication of hourglass-like ZnO particles with enhanced blue emission

Hourglass-like ZnO microcrystals with circular cross sections have been synthesized through a solvothermal method. Two kinds of morphologies have been observed: glabrous hourglasses with relatively smooth surface which show single-crystalline diffraction behavior; and crinite ones covered by irregular ZnO nanowires with diameters of about 20-30 nm and lengths up to 200 nm which show polycrystalline diffraction behavior. Time-dependent experiment is introduced to reveal the growth mechanism. Moreover, it was found that both the reaction temperature and the solution environment play a key role in the fabrication of ZnO hourglasses. The ZnO hourglasses have reduced ultraviolet emission and enhanced blue emission with a dominant peak at 467.2 nm and three weak peaks at 451, 481, and 492 nm.