Heteroepitaxial nucleation and growth of complex coatings at mineral/water interfaces

All realistic mineral surfaces in natural waters can be expected to be coated, and their reactive properties influenced by the presence of coatings. Heteroepitaxial growth is the templated growth of compositionally distinct but structurally similar phases on a mineral substrate and leads to coatings that can mask the properties of the underlying bulk phase. It is a common but challenging interfacial process to understand because the nature of the coatings is a complex function of solution conditions, solubility, and interfacial structure, and because of difficulties in detection and probing thin, structurally similar minerals on minerals. The long-term vision of this research is to provide fundamental insights into the formation of heteroepitaxial coatings and the mineral/fluid interfacial properties that emerge as they form and to develop a microscopy theory of heteroepitaxial nucleation and growth of complex multiphase mineral/fluid interfaces.
Using the nucleation and growth of metal carbonates as a model system, we will quantify the effects of potential controlling factors, such as lattice mismatch, saturation state, and kinetics of water exchange. EMSL’s experimental capabilities will be employed to overcome current limitations and yield fundamental insights. Atomic force microscopy will be used to probe the mechanisms of nucleation and the time dependence of the size and morphology of growth features, X-ray photoelectron spectroscopy will be used to determine the chemical nature of the epitaxial coatings, and scanning electron microscopy will be used to reveal the physical nature of the precipitates.