Morphology and Crystallography of Aluminum Nitride Whiskers

Highly pure and dense AIN whiskers were produced by carbothermal reaction of an alumina and a carbon source at 1800°C under flowing nitrogen. The whiskers grew via a VLS mechanism where there is a strong interaction between the liquid catalyst and the substrate/support, resulting in a complete lack of droplets at the whisker tips. The whiskers can be described as long and straight single crystals, free of planar defects, having a diameter of 2–30 μm and a length of 0.5–10 cm. They exhibited two different morphologies, planar and serrated. SADPs indicate that their lateral surfaces fall in a great circle of a stereographiv projectiov, joining two pyramidal poles such as the ( 1 101)–(10 1 1). It is suggested that branching in these whiskers occurs by keeping active one of the pyramidal planes and activating a new one.