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In situ AFM observations of the interaction between calcite (1014) surfaces and Cd-bearing aqueous solutions



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Pérez Garrido, Carlos and Fernández-Díaz, Lourdes and Pina Martínez, Carlos Manuel and Prieto Rubio, Manuel (2007) In situ AFM observations of the interaction between calcite (1014) surfaces and Cd-bearing aqueous solutions. Surface science, 601 . pp. 5499-5509. ISSN 0039-6028

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Official URL: http://www.elsevier.com/locate/susc


In situ atomic force microscopy (AFM) observations of the interaction between calcite ð1014Þ surfaces and Cd-bearing aqueous solutions
have been carried out, by maintaining the solutions static in the AFM fluid cell. The interaction involves the dissolution of the
original surface and the simultaneous epitaxial growth of multilayer three-dimensional islands 2.75 nm in height of Cd-rich members
of the CdxCa1xCO3 solid solution. Dissolution occurs by the retreating of steps and the formation and growth of etch pits. Both the etch
pits and the multilayer islands are elongated along the [421] direction. Such an unusual elongation direction is interpreted as a kinetic
effect controlled by both the structural characteristics of the calcite (1014) surface and the structure and elastic properties of the overgrowth.
Using aqueous solutions highly concentrated in cadmium, the formation of ~ 2.75 nm thick islands occurs after the initial growth
of a solid solution monolayer ~ 0.3 nm thick, which finally dissolves as the islands grow. This effect seems to be a result of the coherent
strain energy accumulated in the substrate–monolayer interface. Significantly, the dissolution rate of the calcite surface decreases when
the concentration of Cd2+ in the aqueous solution increases, suggesting that, together with co-precipitation, Cd adsorption plays an
important role in the interaction process. During co-precipitation, the progressive coalescence of the Cd-rich islands results in formation
of a nanometric epitaxial layer on the calcite (1014)surface. This layer armours the substrate from further dissolution and determines
the end of the process at a ‘‘partial’’ pseudo-equilibrium endpoint.

Item Type:Article
Uncontrolled Keywords:Calcite; Cd; Dissolution–crystallization; Atomic force microscopy
Subjects:Sciences > Geology > Crystallography
ID Code:14065
Deposited On:19 Dec 2011 11:52
Last Modified:11 Dec 2018 08:46

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