Synthesis and sintering of aluminium nitride nano-particles

Aluminum nitride (AlN) nano-particles were synthesized from aluminum chloride by sodium reduction in liquid ammonia. A liquid solution of sodium dissolved in ammonia was employed as a reduction-nitridation agent, which enabled direct nitridation of aluminum chloride at -45°C The synthesized particles were heat-treated at 1000°C in vacuum, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET surface area measurement. The results indicated that the products were hexagonal wurtzite AlN particles, with a specific surface area of 262 m²g^-1. Spark plasma sintering (SPS) process was used to consolidate the as-prepared AlN nanoparticles, and dense AlN ceramic (>98.5%) with average grain size of 200-400 nm was obtained at 1600°C without the use of sintering additives.