In-situ observations of nucleation processes in an ionic liquid as a solvent using TEM

Abstract

  We believe that elucidation of the role of hydrated layer on the surface of crystals and growth units, and incorporation of significances of nanoscale materials are the keys to understand nucleation processes. We are trying to observe at the moments of nucleation in nanoscale using advanced transmission electron microscopies (TEM) for long years. Here, we report results of nucleation of sodium chlorate as an example from an ionic liquid instead of water as a solvent. Ionic liquid has negligible vapor pressure and is not charged up by electron-beam irradiation due to its relatively higher electrical conductivity and, therefore, has a great potential to study crystallization using TEM. Nevertheless, observation of nucleation processes is still very difficult even used ionic liquids. To overcome the difficulties, the nucleation processes have been expected from the results of the opposite process, i.e., by observation of dissolution processes. We successfully found the concurrent formation of two polymorphic crystals without the contribution of an amorphous intermediate stages at the equilibrium concentration.