Atomistic grain boundary migration in Al2O3

Grain boundary (GB) migration is one of the most important phenomena in materials science, which plays a key role in modifying the microstructures and properties of polycrystalline ceramic materials. Understanding how GB migrates is thus a fundamental and critical issue for future ceramic material design. While the understanding of GB atomic structures has evolved significantly over the past several decades due to the progress of atomic-resolution electron microscopy and atomistic simulation, the understanding of the atomistic grain boundary migration is still lacking. The present article briefly reviews our recent progress on the direct observation of atomistic GB migration in ceramic material by atomic-resolution scanning transmission electron microscopy (STEM). Using Al₂O₃ as a model material, we found that the atomistic GB migration proceeds with atom shuffling accompanied by GB structural change and/or nucleation of disconnection, which is highly dependent on the GB atomic structures.