Effect of gaseous carbon on the carbothermal reduction and nitridation of alumina under a flow of nitrogen

Abstract

The carbothermal reduction and nitridation (CRN) of α-alumina (α-Al₂O₃) to aluminum nitride (AlN) with gaseous carbon under a flow of nitrogen was investigated by X-ray diffraction and ²⁷Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The mixture of α-Al₂O₃ and gaseous carbon was obtained by the reaction of aluminum sulfide (Al₂S₃) with carbon monoxide (CO). The AlN formation commenced at 1100°C, which is the lowest temperature reported for AlN formation by the CRN reaction. The involvement of gaseous carbon in the CRN reaction, which has not previously been reported in the CRN reaction, greatly reduced the nitridation temperature of α-Al₂O₃.