Spatial and evolutionary aspects of nucleation in diffusing-reacting systems

Abstract

Nucleation behaviour in diffusing-reacting systems involves spatial phenomena that are explainable by means of spatial considerations. Particularly, precipitate locations may be justified from the profiles of different physico-chemical parameters at the nucleation time. However, this instantaneous observation is not enough to explain other aspects (nucleation density, metastability level, etc.) that are in relation with the system evolution. Evolutionary variables must be introduced to account for experiments in systems of this kind. In this paper a parameter, the supersaturation rate, is quantified from experimental data of supersaturation evolution. The study is applied to growth of barium and strontium carbonates in a U-tube gel system. Supersaturation rates have an important bearing on the supersaturation level at the nucleation time and consequently on the nucleation density.