Anatomy of a Complex Crystallization Pathway

Crystallization is ubiquitous in nature. For example, it occurs in cloud formation and precipitation, and the Earth's crust is a tapestry of crystalline structures, shaping landscapes and ecosystems. Despite its ubiquity, however, our understanding of crystallization remains incomplete, especially for complex crystals, which exist in a plethora of systems spanning many length scales, such as intermetallic compounds and colloidal assemblies. In this work, we study and compare the macroscopic and microscopic crystallization pathways of two prototype systems in which the components have fundamentally different interactions. One system has particles with interactions characteristic of those in metallic compounds, the other one with shaped particles whose interactions are emergent entropic forces. By examining the pathways on the macroscopic level, we found that both systems are polymorphic and share the same crystal polymorphs. More remarkably, the microscopic pathways of the two systems exhibit similar traits due to the similarities in their local structural environments (LSEs), despite the stark difference in the origins of their particle interactions.