Crystallization Kinetics of Concurrent Liquid-Metastable and Metastable-Stable Transitions, and Ostwald's Step Rule.

Experimental measurements of colloidal crystallization in a wide range of volume fractions of charged particles were performed to investigate the liquid-metastable-stable transition process. To fit the obtained experimental data, we developed a theoretical model to formulate the kinetics of the concurrent liquid-metastable and metastable-stable transitions. This model is well-supported by our observations. We found that when the ratio of the metastable-stable transition rate to the liquid-metastable rate is very large, the metastable state can become undetectable, although it still exists, offering a possible explanation for very few exceptions to Ostwald's step rule.