diagram of liquid cell with Si3N4 membranes
Image courtesy of Minerals

Abstract

The study of nucleation and growth from supersaturated ion solutions is a key area of interest in biomineralization research and beyond with high-resolution in situ imaging techniques such as liquid cell transmission electron microscopy (LCTEM) attracting substantial attention. However, there is increasing experimental evidence that experiments performed with this technique differ from those performed in bulk solutions due to the spatial restriction, which is a prerequisite for LCTEM to provide electron transparent samples. We have performed 2D Finite Elements (FE) simulations to study the impact of confinement on the steady state concentration profiles around a nanoparticle in a supersaturated solution of the constituent ions. We find that confinement below a critical value significantly reduces the concentration of available ions in solutions and hence the stability of the precipitates. These findings could explain the necessity to substantially increase ion activities of Ca2+ and CO32− to induce precipitation in LCTEM.

Impact Statement

This paper explores the effect of spatial confinement which is inherent for LC-TEM on ion concentration and its impact on nanomaterial growth. Theoretical calculations show a significant ion depletion in the vicinity of precipitate particles as a result of confinements below one micron.