Crystal growth kinetics of nanocrystalline ZnS under surface adsorption

The crystal growth mechanism, kinetics, and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study, by introducing the strong surface adsorption of the concentrated NaOH, two-stage crystal growth kinetics of ZnS nanoparticles was observed. In the first stage, the primary articles grow into a size over a hundred times of the original volume and the growth is controlled by the crystallographically specific oriented attachement. The first stage data were fitted by the "multistep OA kinetic model" built based on the molecular collision and reaction. In the second stage, following the dispersal of nanoparticles, an abrupt transistion from asympotic to parabola growth kinetics occurs, which can be fitted by a standard Ostwald ripening volume diffusion model. The presence of surface adsorption causes the two-stage growth kinetics and permits an almost exclusive OA-based growth to dominate in the first stage.