A Unified Kinetic Picture of Heterogeneous and Homogeneous Crystallization from Transition Rate

Abstract Heterogeneous and homogeneous crystallization exhibit distinct phase transition kinetics. However, due to the difficulty of realizing both heterogeneous and homogeneous crystallization under one identical thermodynamic condition, an independent comparison of the two remains lacking. Inside a colloidal system, we experimentally realize a systematic switching from heterogeneous to homogeneous crystallization under one identical thermodynamic condition, capture the entire crystallization process of each colloidal particle with confocal microscopy, and discover a universal kinetic picture of the two situations. In the heterogeneous crystallization, we reveal an unexpected variation of critical nucleus size with boundary disorderness instead of contact angle, which violates the classical nucleation theory but enables the systematic switching. Moreover, analogous to the reaction rate in chemical reactions, we theoretically propose and experimentally measure the crystallization transition rate, which quantifies the transition probability between any two crystallization intermediate structures identified by the bond order parameters. To our surprise, regardless of heterogeneous or homogeneous crystallization, all 22 kinetic transition rates fall onto universal master curves throughout both nucleation and growth stages, which unifies the two distinct crystallization situations into a universal kinetic picture, i.e., all transition probabilities only depend on the local order parameter but not the heterogeneous or homogeneous mode.