Observations of Dense Liquid Phase-Assisted Nanocrystal Growth and Coalescence

Considerable theoretical and experimental efforts have been made on the nonclassical crystallization theory for a better understanding of the crystallization process to improve nanomaterial design and preparation. It is commonly suggested that nucleation often occurs through a multiple-step mechanism with an amorphous dense liquid phase (DLP) intermediate, which plays a crucial role during the nucleation process from supersaturated solutions to nanocrystals. The behaviors of the DLP after nanocrystal nucleation, however, are largely unknown. Herein, using in situ liquid phase transmission electron microscopy, we examine the role of the DLP throughout the growth of palladium nanocrystals. The DLP mediates mass transportation between particles and provides a relatively stationary liquid environment in which the metastable nanoparticles can grow and restructure. Our observations bring new insight into the study of the DLP and the role it plays in crystallization.