Synthesis and characterization of single-crystalline alumina nanowires

Alumina nanowires were synthesized on large-area silicon substrate via simple thermal evaporation (method) of heating a mixture of aluminum and alumina powders without using any catalyst or template. The phase structure and the surface morphology of the (as-grown) sample were analyzed by X-ray diffractometry(XRD) and scanning electron microscopy(SEM), respectively. The chemical composition and the microstructure of the (as-grown) alumina nanowires were characterized using transmission electron microscope(TEM). The nanowires are usually straight and the single crystalline has average diameter of 40 nm and length of 35 μm. The growth direction is along the [002] direction. Well aligned alumina nanowire arrays were observed on the surface of many large particles. The catalyst-free growth of the alumina nanowires was explained under the framework of a vapor-solid(VS) growth mechanism. This as-synthesized alumina nanowires could find potential applications in the fabrication of (nanodevices.)