Quasi-aligned, high-aspect-ratio AlN micro- and nanostructures were synthesized under high nitrogen pressure by the exothermic reaction of an Al + 0.015 mol (C2F4)(n) mixture. Structurally uniform AlN micro-and nanofibers with hexagonal and cylindrical morphologies were obtained when the system temperature was maintained within the range of 1600-1700 degrees C. The fibers had aspect ratios as high as 2000, diameters in the range of similar to 0.05-20 mu m, and were similar to 100-1000 mu m in length. High-resolution transmission electron microscopic and selected area diffraction analyses indicated that the as-synthesized AlN micro- and nanostructures are perfectly single crystalline with preferential growth along the [0 0 1] direction. Branching was also observed in some of the micro-fibers, giving rise to randomized, two-dimensional comb textures. Based on the results obtained in the present study, a mechanism for the formation of AlN micro- and nanostructures under combustion conditions was proposed. (C) 2011 Elsevier B.V. All rights reserved.