Bimodal crystallization rate curves of a molecular liquid with fieldinduced polymorphism

Abstract

In this study, we use dielectric spectroscopy to explore how frequency and amplitude of an applied strong electric field affect the overall crystallization kinetics over a range of temperatures, focusing on a molecular system with field-induced polymorphism: vinyl ethylene carbonate (VEC). The volume fraction of the field-induced polymorph can be controlled by the parameters of the high-electric field, i.e., frequency and amplitude. We find that the crystallization rate maximum of the field induced polymorph is located at lower temperatures relative to the that of the regular polymorph. The temperature of the highest crystallization rate for the regular polymorph was found to be unaffected by the electric field, but the overall rates increase with increasing field amplitude. The dimensionality of crystal growth is also analyzed via the Avrami parameter and is frequency invariant but affected by the field amplitude. Our results demonstrate that a detailed knowledge of the influence of high fields on crystallization facilitates control over the crystallization behavior and the final product outcome of molecular systems, providing new opportunities for material engineering and improving pharmaceuticals.