Pina, Carlos M.; Merkel, Casjen; Jordan, Guntram
On the Bimodal Effects of Silicic Acids on Calcite Growth.
In: Crystal Growth and Design, Vol. 9, No. 9: pp. 4084-4090
Full text not available from 'Open Access LMU'.
The effects of silicic acids on calcite growth area model for theeffects of partially polymerized additives on crystal growth. Atalkaline pH, silicic acid polymers coexist with small mono- andoligomers, Atomic force microscopy (AFM) showed that large polymerspromote two-dimensional nucleation, while mono- and oligomers have abimodal promoter/inhibitor effect on step propagation. This bimodalitycan be interpreted as the result of attachment of mono- and oligomersalong the steps along with a modification of the kinetics of kinkgeneration and/or propagation. The bimodal step kinematic effect isaccompanied by a single morphologic effect: growth islands transformfrom a rhombus into an ellipse. This effect has been reported for otheradditives, indicating that many additives generate few morphologies.Such a convergence limits the versatility of chemical control onbiomorphogenesis. Contrarily, the strong kinetic effect of silicic acidsmay make them very efficient controllers of biomorphogenesis, if coupledwith a physical shape control, for example, by templates. Thus, silicicacids show a unique bimodality as a controller of calcitebiomineralisation and its an abundant biomineral.