Capturing the Moment of Emergence of Crystal Nucleus from Disorder

Abstract

Crystallization is the process of atoms or molecules forming an organized solid via nucleation and growth. Being intrinsically stochastic, the research at an atomistic level has been a huge experimental challenge. We report herein in situ detection of a crystal nucleus forming during nucleation/growth of a NaCl nanocrystal, as video recorded in the interior of a vibrating conical carbon nanotube at 20−40 ms frame −1 with localization precision of <0.1 nm. We saw NaCl units assembled to form a cluster fluctuating between featureless and semiordered states, which suddenly formed a crystal. Subsequent crystal growth at 298 K and shrinkage at 473 K took place also in a stochastic manner. Productive contributions of the graphitic surface and its mechanical vibration have been experimentally indicated.

Evolution of the Local Structure in the Sol–Gel Synthesis of Fe3C Nanostructures

“…This reflects the similar observations that have been made in solution-state crystallization processes, such as the formation of amorphous NaCl clusters followed by a sudden onset of crystallization. 35 …”

Microscopic Kinetics Pathway of Salt Crystallization in Graphene Nanocapillaries

“…Conventional understanding suggests that NaCl follows a one-step classical nucleation pathway and grows into its conventional cubic rock salt structure (B1-NaCl) [21,22]. Using atoresolution in situ transmission electron microscopy (TEM), we reveal that, in a GLC, NaCl unexpectedly crystallizes into hexagonal-shaped crystallites, which predominantly expose their f110g facets instead of the conventional f100g facets.…”

Multistep nucleation of anisotropic molecules

“…Here we show by molecular simulations that multistep nucleation takes place in a first-order phase transition of a simple model system composed of a single species of anisotropic particles. Direct real-space observation of the microscopic processes of phase transition, although there have been reports on atomistic 30 – 32 and colloidal systems 33 , 34 , is still an experimental challenge. Molecular simulations have thus provided an alternative and promising means to elucidate the microscopic mechanisms of phase transition phenomena, in particular nucleation processes.…”