Crystal Growth Rate Dispersion versus Size-Dependent Crystal Growth: Appropriate Modeling for Crystallization Processes

Abstract

Crystal growth rate dispersion (GRD) and size-dependent crystal growth (SDG) models are models to extend McCabe’s ΔL Law to more accurately account for variation in the crystal growth rates within a population of crystals. GRD is a phenomenon where the crystal growth rate either fluctuates randomly over time or varies over a population of crystals. SDG is where the growth rate of a crystal depends on its size, typically with growth rates assumed to increase monotonically with crystal size. Although it has been recognized for more than 30 years that, except for extremely small crystals, SDG is an artifact of GRD, it is still common in the literature for GRD in experimental results to be modeled using SDG models. This discussion will present some background and new experiments on the mechanism and extent of GRD to demonstrate that GRD is a real phenomenon, whereas SDG is largely an artifact, and some modeling work to demonstrate that SDG models cannot successfully replicate crystal size distribution data th...