Crystal Nucleation Kinetics and Mechanism: Influence of Interaction Potential

TL;DR

This study investigates how different interaction potentials influence nucleation pathways and crystal structures in colloidal systems, revealing that polymorph selection can be controlled without affecting nucleation rates.

Contribution

It demonstrates that modifying the interaction potential alters nucleation pathways and polymorph outcomes while maintaining similar nucleation rates.

Findings

Nucleation rates are comparable for 12-6 and 7-6 potentials.

Different crystal structures (FCC and BCC) emerge depending on the potential.

Polymorph selection can be achieved through interaction potential modifications.

Abstract

Modulating liquid-to-solid transitions and the resulting crystalline structure for tailored properties is much desired. Colloidal systems are exemplary to this end, but the fundamental knowledge gaps in relating the influence of intermolecular interactions to crystallization behavior continue to hinder progress. In this study, we address this knowledge gap by studying nucleation and growth in systems with modified Lennard-Jones potential. Specifically, we study the commonly used 12-6 potential and a softer 7-6 potential. The thermodynamic state point for the study is chosen such that both systems are investigated at the same level of supercooling and pressure. Under these conditions, we find that the nucleation rate for both systems is comparable. Interestingly, the nucleation pathways and resulting crystal structures are different. In the 12-6 system, nucleation and growth occur predominantly through the FCC structure. Softening the potential alters the critical nucleus composition and introduces two distinct nucleation pathways. One pathway predominantly leads to the nucleus with a body-centered cubic (BCC) structure, while the other favors the face-centered cubic (FCC) arrangement. Our study illustrates that polymorph selection can be achieved through modifications to intermolecular interactions without impacting nucleation kinetics. The results have significant implications in designing approaches for polymorph selection and modulating self-assembly mechanisms.