Mineral surfaces serve as substrates for heterogeneous nucleation in aqueous solutions and can support the growth of heteroepitaxial coatings if the atomic arrangement of the substrate closely matches that of the nucleating phase. Heteroepitaxial coatings play an important role in understanding mineral surface reactivity as coatings of even nanometer scale can significantly affect some properties of the mineral-water interface. Therefore, we aim to elucidate in this work the kinetics and mechanisms of heteroepitaxial nucleation and growth using the formation of metal carbonates on calcite as a model system. Cadmium-, manganese-, and cobalt-bearing aqueous solutions were selected to cover nominal lattice misfits between -4% and -15%. In-situ atomic force microscopy was employed to determine the dependence of growth rates and mechanisms on supersaturation and extent of lattice misfit; X-ray photoelectron spectroscopy was used to probe precipitate composition; and high-resolution transmission electron microscopy revealed the atomic-scale structure of the calcite-metal carbonate interfaces.

Heteroepitaxy at mineral-water interfaces: Nucleation and growth of metal carbonates on calcite

247th National Meeting (2014)

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