The growth of AlN dendritic crystals with uniform morphology by an aluminum microdroplet localization approach

We developed an attractive combustion approach for synthesizing uniformly shaped AlN dendritic crystals by combustion of Al + 0.1AlF3 + kAl2O3 powder mixtures in a nitrogen atmosphere. The combustion temperature measured for various k values was between 1650 and 1750 °C and the micro-droplets of Al formed in the beginning stages of the process were enveloped by the solid layers of Al2O3, and the subsequent multipoint nucleation and crystallization produced morphologically and size uniform dendritic crystals. We proposed a theoretical model for calculating the thickness and the number of Al2O3 layers around of Al microdroplets at known concentration of Al2O3. Depending on the concentration of Al2O3, these structures were simple stars with six points and stellar dendrites with multiple petals.