Aerosol Synthesis of Aluminum Nitride Powders

Abstract

ABSTRACTWe describe a new laboratory-scale aerosol process for producing AIN powder. A two-stage reactor design is used. In the first stage, triethyl aluminum (TEA = AI(CC2H5 )3) and NH3 react to form an aerosol adduct in a laminar flow diffusive mixing zone. The aerosol then enters the furnace stage, where it is converted to AIN. We have examined the influence of the major operating variables (e.g., inlet TEA concentration, reactor residence time, and furnace temperature) on the particle size and distribution, yield, and efficiency. For example, increasing the TEA concentration from 0.12 to 1.30 µmol/cm3 causes an increase in the mean particle diameter (from 0.07 to 0.13 Pim), a slight increase in polydispersity (from 0.31 to 0.43), and a decrease in yield efficiency (from 90% to 73%). In contrast, decreasing the reactor residence time (by increasing the flow rate) has little effect on mean particle diameter, but causes a significant increase in yield efficiency (approaching 100%). The overall behavior of the reactor suggests a model in which the particle size distribution of the final product is determined primarily by the aerosol formation steps in the mixing stage (i.e., nucleation, growth, and coalescence), while the composition and crystallinity of the product are determined by furnace conditions.