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Uncovering the Atomistic Mechanism for Calcite Step Growth
Author(s) -
De La Pierre Marco,
Raiteri Paolo,
Stack Andrew G.,
Gale Julian D.
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201701701
Subject(s) - calcite , nucleation , carbonate , ion , limiting , chemical physics , chemistry , adsorption , mineralogy , crystallography , materials science , mechanical engineering , organic chemistry , engineering
Abstract Determining a complete atomic‐level picture of how minerals grow from aqueous solution remains a challenge as macroscopic rates can be a convolution of many reactions. For the case of calcite (CaCO 3 ) in water, computer simulations have been used to map the complex thermodynamic landscape leading to growth of the two distinct steps, acute and obtuse, on the basal surface. The carbonate ion is found to preferentially adsorb at the upper edge of acute steps while Ca 2+ only adsorbs after CO 3 2− . In contrast to the conventional picture, ion pairs prefer to bind at the upper edge of the step with only one ion, at most, coordinated to the step and lower terrace. Migration of the first carbonate ion to a growth site is found to be rate‐limiting for kink nucleation, with this process having a lower activation energy on the obtuse step.