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

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.