Visualizing the crystallization of sodium chloride under supersaturated condition

Crystallization in supersaturated solution plays a fundamental role in a variety of natural and industrial processes. However, a thorough understanding of crystallization phenomena in supersaturated solution is still difficult because the real-time visualization of crystallization processes under supersaturated condition is a great challenge. Herein, an electron beam-induced crystallization method was carried out in in situ liquid cell transmission electron microscopy (TEM) to visualize the crystallization of NaCl under supersaturated condition in real time. Crucial steps and behaviors in the crystallization of NaCl were captured and clarified, including the growth of NaCl nanocrystals with different morphologies, the formation of initial crystalline seeds from amorphous ion clusters, and the non-equilibrium growth behaviors caused by uneven distribution of precursor ions. This study provides the real-time visualization of detailed nucleation and growth behaviors in NaCl crystallization and brings an ideal strategy for investigating crystallization phenomena under supersaturated condition.