Multistep Crystal Nucleation:  A Kinetic Study Based on Colloidal Crystallization

Abstract

Crystallization via an amorphous precursor, the so-called multistep crystallization (MSC), plays a key role in biomineralization and protein crystallization. MSC has attracted much attention in the past decade, but a quantitative understanding of it has so far not been available. The major challenge is that the kinetics governing the nucleation of crystals occurring in the metastable amorphous precursor remains unclear. In this study, the kinetics of MSC is addressed experimentally. Most importantly, a mathematical method is developed to calculate the local nucleation rate of the crystals in the amorphous precursor, which is not accessible to conventional methods. This local nucleation rate is critical to the understanding of MSC, but it has never been dealt with experimentally because of the difficulties of in situ observation. With the local crystal nucleation rates, the supersaturation for crystallization and the crystal-liquid interfacial free energy in the amorphous precursor are evaluated.

Phase-field crystal modeling of heteroepitaxy and exotic modes of crystal nucleation

“…(b) In agreement with theory [18], molecular dynamics simulations [19], and colloid experiments [20][21][22], recent investigation relying on the PFC model have shown that at large supersaturations/undercoolings crystal nucleation is a two-step process, in which an amorphous precursor assists the formation of the crystalline phase [4,6,8].…”

“…Apparently, this phenomenon is highly relevant not only for colloids [18,21,22,37], but for such simpler systems as the Lennard-Jones fluid [18] and the hard sphere system [19], raising the possibility that the presence of an amorphous precursor might be a general feature of crystal nucleation in highly undercooled or supersaturated liquids. In this subsection, we investigate the structural aspects of this process within the framework of the PFC model.…”

Nucleation: What Happens at the Initial Stage?

“…Nevertheless, this assumption has been challenged by evidence from simulations [10][11][12] and experiments. [13][14][15] The key point of this evidence is that in crystallization, nucleation begins with a metastable structure and the stable structure is reached subsequently. This picture is consistent with the prediction of the Ostwalds rule.…”

Effect of Acetic Acid in TiCl4Post-Treatment on Nanoporous TiO2Electrode in Dye-Sensitized Solar Cell

“…This suggests that a TiCl 4 posttreatment can improve the binding of the dye. 19) In addition, a decrease in surface area results from the reduction of the specific area states that are inaccessible to the dye due to steric constraints. 20) The amount of dye loading with 15% acetic acid is decreased slightly because too much reduction of pore size can offset the performance of acetic acid.…”