Gas-based reduction and nitridation for synthesis of vanadium nitride: Kinetics and mechanism

We investigate the isothermal kinetics of the reduction and nitridation of V 2 O 3 using NH 3 . The reaction mechanism is also discussed based on the thermodynamic and experimental results. The reaction procedure between V 2 O 3 and NH 3 can be divided into two stages. The first stage is mainly the deoxygenation process, whereas the second is the nitridation process. The deoxygenation process follows a two-dimensional phase boundary reaction model, and a modified integrated model (IM + diffusion) was proved to be the best function at temperatures above 1023 K. For the second stage, the three-dimensional diffusion model is determined as the mechanism function. Thermodynamic analysis predicts the feasibility between V 2 O 3 and NH 3 to form VN . The VN product is a solid solution (VN x O y ) (0 < x,y < 1, x + y = 1), which can be formed at 873 K. The Rietveld refinement analysis indicates the N content of VN x O y gradually increases with increasing temperature. The highest N content is approximately 15.83% at 1073 K for 2 h.