title: Kinetic Pathways and Mechanisms of Two-Step Nucleation in Crystallization.
abstract: Crystallizations often pass through multiple intermediate structures before reaching the final state, such as amorphous precursors, polymorphs, or denser liquid droplets. However, the atomistic pathways from these metastable phases to final crystals still remain unclear. Here, we investigated the structure evolution process from liquid to final crystals of homogeneous nucleation by atomic-scale simulations and analyzed the intrinsic mechanisms that influence the nucleation pathways. Three different pathways of two-step nucleation were found by visualizing the precursors' evolutions, and some new micromechanisms of two-step nucleation are revealed. We suggest that the solid bond fluctuations can trigger the formation of intermediate precursors, while the precursors' packing density dominates the structural transformation pathways from intermediate phases to crystals. These findings not only shed light on the mechanisms of nucleation but also provide guidance for future refinements of two-step nucleation theory.
authors.affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , Xi'an 710072, People's Republic of China.
authors.forename: Can
authors.initials: C
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , Xi'an 710072, People's Republic of China.
authors.forename: Jincheng
authors.identifier: http://orcid.org/0000-0003-3910-1020
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , Xi'an 710072, People's Republic of China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , Xi'an 710072, People's Republic of China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , Xi'an 710072, People's Republic of China.
authors.forename: Sai
authors.initials: S
authors.lastname: Tang