Modeling and simulation of grain growth in Si3N4. III. Tip shape evolution Original Research Article

Simulations based on the anisotropic Ostwald ripening model have been performed for the tip shape evolution of the β-Si3N4 crystal in the liquid phase. It was found that tip shape is a function of the liquid concentration and the relationship between the interfacial reaction and diffusion constants. Depending on the concentration of the liquid phase, a convex, almost flat, or concave surface appeared at the tip surface. The following two factors are crucial for understanding the development of concavity at the tip surface of the β-Si3N4 crystal: (1) strong growth anisotropy of the β-Si3N4 crystal that is the interfacial reaction and diffusion controlled kinetics of the (100) and (001) surfaces, respectively, and (2) supersaturation of the liquid phase.