Hierarchical Al2O3Nanobelts and Nanowires: Morphology Control and Growth Mechanism

We report here a tunable synthesis of single crystalline hierarchical α-Al 2 O 3 nanobelts and nanowires by selectively applying a vapor−liquid−solid (VLS) and vapor−solid (VS) strategy in a chemical vapor process. The resultant nanostructures were characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray powder diffraction. The hierarchical nanobelts were generated by a noncatalytic oriented growth of Al 2 O 3 vertical to the {110} planes enclosed with {001} and {100} planes following a VS mode. The hierarchical nanowires were obtained through a catalytic growth in a VLS process. This well-controlled synthesis strategy is expected to be applicable to fabrication of other hierarchical nanobelts or nanowires.