Transformation of Amorphous Calcium Carbonate in Air
| Autor: | Florian Gallien, Martin Dietzel, Daniel E. Gerard, Florian Konrad |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Nanotechnology
02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Amorphous calcium carbonate 0104 chemical sciences law.invention chemistry.chemical_compound chemistry Physisorption Chemical engineering law Metastability Monolayer General Materials Science Relative humidity Crystallization Thin film 0210 nano-technology Dissolution |
| Zdroj: | Crystal Growth & Design. 16:6310-6317 |
| ISSN: | 1528-7505 1528-7483 |
| Popis: | In air, the mechanisms of amorphous calcium carbonate (ACC) transformation into crystalline polymorphs of CaCO3 and whether the atomic ordering is attributable to a solid-state transformation or a dissolution and reprecipitation process are still under debate. While some studies observed a significant influence of relative humidity on ACC transformation, other studies suggested a dehydration process of ACC prior to crystallization. In the present study, we focus on the metastability of additive-free ACC in air and in particular on its interaction with relative humidity. Our findings indicate that the transformation of ACC into crystalline CaCO3 is triggered only after the physisorption of a critical H2O level. Consequently, ACC metastability was prolonged by retarding H2O uptake and by keeping the physisorbed H2O below the critical level, ACC remained in its metastable state. Therefore, the conceptual formation of a “thin film” of about four monolayers of physisorbed H2O is considered to govern the transf... |
| Databáze: | OpenAIRE |
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