Formation and characterization of cubic AlN crystalline in a carbothermal reduction reaction

Cubic aluminum nitride has been obtained in carbothermal reduction reaction at 1700–1800 °C under a flowing nitrogen stream. The as-synthesized products were characterized by XRD, SAD and IR spectrum. The results indicated the product was consisted of wurtzite hexagonal AlN, cubic AlN and corundum. It is speculated that the nucleation and growth of cubic AlN result from the transition of cubic AlON, since intermediate AlON in carbothermal reduction has the same cubic symmetry as cubic AlN. Cubic AlN are unstable metastable phase and are easily transformed into stable hexagonal AlN via crystalline transition with increasing reaction temperature or reaction time. The formation mechanism of cubic AlN is also discussed.