A thorough understanding of growth processes at carbonate mineral-water interfaces is essential to many geochemical processes, including geologic CO2 sequestration in deep aquifers. In the present work, epitaxial growth of carbonates on calcite (104) surfaces has been promoted by immersing cleaved single crystals in divalent metal cation-bearing solutions supersaturated with respect to the overgrowing phase. Cd2+, Mn2+, and Co2+ solutions that cover a range of lattice mismatches (4-15%) and supersaturations were employed to probe the effects of lattice mismatch and solution chemical condition on the kinetics and mechanisms of heteroepitaxial nucleation and growth. In situ AFM experiments indicated that carbonate growth proceeds via the nucleation of a surface precursor that is not fully crystalline (non-classical pathway) but transforms to adopt the calcite structure as growth proceeds. These experiments also showed the transition from growth via spread of three-dimensional multilayer islands to the formation and spread of two-dimensional nuclei.  In addition, XPS, TEM, and APT techniques were employed to ellucidate the composition, structure, and morphology of the overgrowing phases.

Heteroepitaxial growth of carbonates at calcite-water interfaces: Effects of solution chemistry and crystal lattice mismatch

248th National Meeting (2014)

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