Synthesis and evolution of novel hollow ZnO urchins by a simple thermal evaporation process

Delicate hollow ZnO urchins have been fabricated by thermal evaporation of metallic zinc powders in a tube furnace without the use of additive, high temperature, or low pressure. The phase transformation, morphologies, and photoluminescence evolution of the ZnO products were carefully studied and investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra. These studies indicated that the growth of hollow ZnO urchins involves the vaporization of Zn powder, solidification of liquid droplets, surface oxidation, sublimation, and self-catalytic growth of one-dimensional nanowires.