Liquid-Phase-Assisted Catalytic Nitridation of Silicon and In Situ Growth of α-Si₃N₄

Si₃N₄ powders were synthesized with Fe, Co, or Ni as catalysts using Si powder at 1250 °C in a nitrogen atmosphere by liquid-phase-assisted catalytic nitridation synthesis (LPA-CNS). The catalytic effects of the metals on the nitridation of silicon powder were investigated by mixing the powder with 2 wt% by mass of Fe, Co, or Ni in a high-temperature liquid phase in flowing nitrogen. The α-Si₃N₄ micro-morphology could be effectively changed by adjusting the type of catalyst in the initial reaction mixtures. Fe, Co, and Ni promoted the formation of α-Si₃N₄ at 1250 °C and controlled the morphology of the α-Si₃N₄ particles. The hexagonal flakes of α-Si₃N₄ with a better defined morphology were obtained using Ni as the catalyst, compared to that obtained from the other two catalysts.