(754b) On Limits of Metastability in Solution Crystallization: Induction Supersaturation and Spinodal

Our previous research on slowly supersaturated systems suggested that a limit of metastability in solution crystallization can be determined based solely on energetic considerations of nucleation.  For such systems, we define an induction supersaturation (a 'working metastability limit') at a supersaturation at which the energetic barrier to nucleation drops to the order of thermal energy of the system.  In this work, we examine this limit of metastability in light of recent experimental results by several researchers.  We present density functional calculations of energy barrier to nucleation on our experimental data, and estimate the probability of nucleation in a slowly-supersaturated system from this energy barrier.  These results are compared to the predictions based on classical nucleation theory.  A general agreement between the two methods of calculations is observed. The induction supersaturation is contrasted against the spinodal decomposition limit.   Modern concepts of nucleation and metastability limits are revisited in the context of our results, and the implications of our experimental findings are discussed.