Observation of New Dynamics of Transitions among Intermediate Species in Crystal Evolution and Its Role in a Generic Model of Crystallization

Abstract

The mass and phase transitions among intermediate species are unique dynamics in nonclassical crystallization that are under investigation. In this research, we used a pulsed laser to initiate crystallization in its early stages and observed the crystal evolution through transitions and interactions among the intermediate species. The crystal evolution was induced and observed in situ simultaneously by the same electron beam in a transmission electron microscope without a liquid cell environment, thereby eliminating the complexity introduced by the additional nucleation in the precursor solution. The observed mass diffusion among species in an anti-Ostwald ripening way indicated that crystallization systems were composed of intermediate species in various phases. We found that these intermediate species were not like rigid building blocks but kept changing in size and phase and evolving in multistage transitions. Considering the observations, we propose a generic model by extending the classical nucleation theories to describe the dynamics of intermediate transitions and all possible crystal evolution pathways, discovered or not.