Real-Time Dynamical Observation of Lattice Induced Nucleation and Growth in Interfacial Solid-Solid Phase Transitions

Uncovering dynamical processes of lattice induced epitaxial growth of nanocrystal on the support is critical to understanding crystallization, solid-phase epitaxial growth, Oswald ripening process, and advanced nanofabrication, all of which are linked to different important applications in the materials field. Here, we conduct direct in situ atomic-scale dynamical observation of segregated Bi layers on SrBi₂Ta₂O₉ support under low dose electron irradiation to explore the nucleation and growth from an initial disordered solid state to a stable faceted crystal by using aberration-corrected transmission electron microscopy. We provide, for the first time, atomic-scale insights into the initial prenucleation stage of lattice induced interfacial nucleation, size-dependent crystalline fluctuation, and stepped-growth stage of the formed nanocrystal on the oxide support at the atomic scale. We identify a critical diameter in forming a stable faceted configuration and find interestingly that the stable nanocrystal presents a size-dependent coalescence mechanism. These results offer an atomic-scale view into the dynamic process at solid/solid interfaces, which has implications for thin film growth and advanced nanofabrication.