Efficient synthesis route to quasi-aligned and high-aspect-ratio aluminum nitride micro- and nanostructures

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 °C. The fibers had aspect ratios as high as 2000, diameters in the range of ∼0.05–20 μm, and were ∼100–1000 μm 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.

► We synthesize quasi-aligned and high aspect ratio AlN nanomaterials. ► We examine temperature history in the combustion wave. ► A formation mechanism of AlN nanostructures was proposed. ► HRTEM image and temperature profile were used to describe reaction mechanism.