Preparation of AlN under vacuum by the alumina carbothermal reduction nitridation method

With good electrical, thermal and mechanical properties, aluminium nitride is widely used in microelectronics and other fields. However, high temperatures are still needed for the method of alumina carbothermal reduction nitridation (CRN) for AlN preparation. Herein, thermodynamics calculation and experimental research were adopted to investigate the preparation of AlN under vacuum by the alumina CRN reaction in order to lower reaction temperature. The results demonstrate that lower pressure benefits the alumina CRN reaction. A single phase of AlN was successfully obtained at 1823 K for 2.5 h with a N2 gas pressure of 300 Pa. Moreover, an underlying growth mechanism of AlN during the alumina CRN process under vacuum was proposed, which is different from that under atmosphere or elevated pressure. The rate limiting step of alumina CRN process was determined. The results also indicate that Al4C3 and Al2OC play important roles in the process of alumina CRN under vacuum.