Multiscale processes of heteroepitaxial nucleation and growth at mineral-water interfaces
EMSL Project ID
47509
Abstract
The goal of the proposed research is to elucidate the mechanisms and quantify the rates of heteroepitaxial nucleation and growth at mineral-water interfaces. Despite several examples of heteroepitaxy occurring in nature or in simulated natural conditions, including the formation of carbonate solid solutions on carbonate minerals, phosphate nucleation on sulfate and phosphate minerals, and hydroxide and carbonate growth on mica, our understanding of heteroepitaxial nucleation and growth at mineral-water interfaces in conditions relevant to natural systems is limited. The limitations of our current knowledge are due to the difficulties in detecting and probing mineral coatings with nanometer-scale dimensions and structures similar to those of their substrates and to the lack of theoretical support to rationalize experimental observations and provide a basis for systematic investigation. Importantly, an understanding of heteroepitaxy at mineral-water interfaces is critical to radically improve current predictive models since this phenomenon leads to non-equilibrium conditions that cannot be described based on thermodynamic equilibrium assumptions. These conditions include undersaturation with respect to the substrate due to armoring by surface coatings, the partitioning of foreign ions in mineral surfaces, and the formation of mineral coatings in undersaturated solutions due to local supersaturation at the mineral-water interface. These effects ultimately need to be incorporated in macroscopic predictive models of the long-term behavior of natural systems.A combined experimental-computational approach will be deployed to overcome current limitations and, for the first time, systematically isolate and quantify the key factors affecting heteroepitaxy at mineral-water interfaces. The proposed approach consists of the combined use of multiple experimental probes with micron- to atomic-scale resolution and the development of a unique multiscale computational model for predicting the formation of heteroepitaxial mineral coatings. The multiscale simulations will provide a quantitative explanation for the experimental observations and a basis for theoretical advances. The formation of metal carbonate phases on the (10.4) calcite surface will be used as a model system. The metal carbonate series provides an ideal system for quantifying the effects of key hypothesized factors, such as lattice misfit, saturation state, and the presence of foreign ions. Atomic force microscopy will be used to probe the time dependence of the size and morphology of nucleation and growth features; high-resolution transmission electron microscopy will be employed to gain insight into the atomic-scale structure of the overgrowths; and x-ray photoelectron spectroscopy, electron energy loss spectroscopy, and atom probe tomography will be used to determine the composition of the mineral coatings. All these capabilities are housed in the EMSL. The multiscale model will consist of a kinetic Monte Carlo approach for simulating the mineral surface coupled with a continuum-level model of the aqueous solution to include the effects of diffusion.
Knowledge gained from this research is expected to help advance geoscientists’ ability to predict the long-term behavior of natural systems, with direct relevance to environmental and energy issues. It will also yield a fundamentally new approach to the geochemical community’s efforts to link atomic-level processes to macroscopic observations.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2012-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Fenter P, SN Kerisit, P Raiteri, and JD Gale. 2013. "Is the Calcite-Water Interface Understood? Direct Comparisons of Molecular Dynamics Simulations with Specular X-ray Reflectivity Data." Journal of Physical Chemistry C 117(10):5028-5042. doi:10.1021/jp310943s
Xu M, ES Ilton, MH Engelhard, O Qafoku, AR Felmy, KM Rosso, and SN Kerisit. 2015. "Heterogeneous growth of cadmium and cobalt carbonate phases at the (101¯4) calcite surface." Chemical Geology 397:24-36. doi:10.1016/j.chemgeo.2015.01.003
Xu M, L Kovarik, BW Arey, AR Felmy, KM Rosso, and SN Kerisit. 2013. "Kinetics and Mechanisms of Cadmium Carbonate Heteroepitaxial Growth at the Calcite (10-14) Surface." Geochimica et Cosmochimica Acta. doi:10.1016/j.gca.2013.11.036
Xu M, L Kovarik, BW Arey, AR Felmy, KM Rosso, and SN Kerisit. 2014. "Kinetics and Mechanisms of Cadmium Carbonate Heteroepitaxial Growth at the Calcite (101¯4) Surface." Geochimica et Cosmochimica Acta 134:221-233. doi:10.1016/j.gca.2013.11.036