Gas-based Reduction and Nitridation for Synthesis of Vanadium Nitride: Kinetics and Mechanism

We investigate the isothermal kinetics of the reduction and nitridation of V2O3 using NH3. The reaction mechanism is also discussed based on the thermodynamic and experimental results. The reaction procedure between V2O3 and NH3 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 V2O3 and NH3 to form VN. The VN product is a solid solution (VNxOy) (0 < x,y < 1, x + y = 1), which can be formed at 873 K. The Rietveld refinement analysis indicates the N content of VNxOy gradually increases with increasing temperature. The highest N content is approximately 15.83% at 1073 K for 2 h.