In Situ Observation of Nucleation and Crystallization of a Single Nanoparticle in Transparent Media

Glass-ceramic is a new type of transparent medium that consists of glassy matrix and nanoparticles (NPs). However, the corresponding atomic-scale growth dynamic of the NPs is unclear due to the lack of an appropriate measurement method. Here, we propose a real-time in situ transmission electron microscopy imaging method to study the growth of ZnO, Ba2LaF7, and Ag NPs inside the transparent glass. Because of the slow nucleation rate and stable growth environment of the glassy matrix under electron beam irradiation, the amorphous-to-crystalline phase transition of all the NPs can be captured in detail. As a result, we reveal the missing puzzle of the nucleation dynamic: the heterogeneous crystallization occurs initially at the interface of an amorphous nanocluster. By directly observing the NPs crystallization processes (i.e., particularly the multistep growth pathways of the NPs from the glassy matrix), we can unify the nonclassical nucleation theory and classical nucleation theory to describe the growth process of NPs.