Crystallization and grain growth in impurity-doped colloidal polycrystals

Joseph D Hutchinson, Fran├žois A Lavergne, and Roel PA Dullens

Phys. Rev. Materials 2022 6 075604

Alloying has long been used to control the properties of crystalline materials. However, the microscopic details of the effects of adding impurities remains poorly understood, as directly imaging these processes is challenging in atomic systems. Here we study how crystallization and grain growth are impacted by impurities in a quenched monolayer of a colloidal polycrystal. The rates of crystallization are unaffected by the impurity concentration and well described by the Johnson-Mehl-Avrami-Kolmogorov model. However, with an increased impurity concentration, more of the system becomes frustrated and does not crystallize. The rate of grain growth is significantly slowed down due to grain boundary pinning. Nevertheless, the evolution of the polycrystalline structure is well described by a single correlation length, and dynamic scaling applies up to relatively large impurity concentrations. Finally, we develop a simple model accounting for both crystallization and grain growth to describe the time evolution of the correlation length, and we find good agreement with our experimental data at all impurity concentrations. Our results shed new light on the interplay between crystallization, grain growth and the presence of impurities in impurity-doped polycrystalline systems.