On the Bimodal Effects of Silicic Acids on Calcite Growth
The effects of silicic acids on calcite growth are a model for the effects of partially polymerized additives on crystal growth. At alkaline pH, silicic acid polymers coexist with small mono- and oligomers. Atomic force microscopy (AFM) showed that large polymers promote two-dimensional nucleation,...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2009 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/52281 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/52281 |
| Access Level: | acceso abierto |
| Palabra clave: | 548 Silicic acids Calcite growth bimodal Cristalografía (Geología) |
| Sumario: | The effects of silicic acids on calcite growth are a model for the effects of partially polymerized additives on crystal growth. At alkaline pH, silicic acid polymers coexist with small mono- and oligomers. Atomic force microscopy (AFM) showed that large polymers promote two-dimensional nucleation, while mono- and oligomers have a bimodal promoter/inhibitor effect on step propagation. This bimodality can be interpreted as the result of attachment of mono- and oligomers along the steps along with a modification of the kinetics of kink generation and/or propagation. The bimodal step kinematic effect is accompanied by a single morphologic effect: growth islands transform from a rhombus into an ellipse. This effect has been reported for other additives, indicating that many additives generate few morphologies. Such a convergence limits the versatility of chemical control on biomorphogenesis. Contrarily, the strong kinetic effect of silicic acids may make them very efficient controllers of biomorphogenesis, if coupled with a physical shape control, for example, by templates. Thus, silicic acids show a unique bimodality as a controller of calcite biomineralisation and as an abundant biomineral. |
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