Bell-mouthed single-crystalline tubular ZnO prepared by a soft solution method

Faceted single-crystalline ZnO tubes were synthesized by a simple soft solution method at 65 deg. C. These tubes are of several micrometers in length and several hundred nanometers in diameter, with bell-mouths on each end. Structural characterizations using electron spectroscopy revealed that these hexagonal ZnO tubes were along [0-bar 0-bar 0-bar 1] direction and side-enclosed by {011-bar 0} facets. The growth of ZnO in hydrothermal condition and the formation of this unusual bell-mouthed structure were discussed on the basis of the observation of ring-shaped nano-crystallites upon decreasing the time for growth