6-Fold-Symmetrical AlN Hierarchical Nanostructures: Synthesis and Field-Emission Properties

The controllable synthesis of nanomaterials with unique morphologies and sizes has attracted increasing interest because of the shape-dependent properties of the nanomaterials. In this article, we report the synthesis of the new 6-fold-symmetrical AlN hierarchical nanostructures including urchinlike and flowerlike ones assembled by AlN nanoneedles through the chemical reaction between AlCl 3 and NH 3 with the vaporization temperature of AlCl 3 between 120 and 165 °C and the reaction temperature higher than 1050 °C. The morphologies, sizes, and densities of the AlN nanostructures could be controllably modulated by changing the reaction temperature and the vapor pressure of AlCl 3 . The formation mechanism of the AlN hierarchical nanostructures has been discussed on the basis of the change in the AlCl 3 vapor pressure and the morphological evolution of the intermediate products. The shape-dependent properties of the AlN products have been observed, and the urchinlike nanostructures showed better optical and field-emission properties in comparison with the flowerlike ones. These results indicate the potential applications of the 6-fold-symmetrical AlN hierarchical nanostructures in optoelectronic and field-emission devices.