Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1518560 | Journal of Physics and Chemistry of Solids | 2008 | 12 Pages |
Abstract
Precipitate calcium carbonates (PCCs) are important industrial products mainly used as fillers. Because of their regular, synthesized characteristics (e.g. grain shape or grain size distribution) PCCs are distinct from natural ground calcium carbonates (GCCs). A thermal study on GCC samples showed only the presence of surface physisorbed water with a monotonic weight loss up to the carbonate decomposition. In the case of PCC samples, two supplementary water releases were observed. The first one appeared at around 525Â K and the second one at around 725Â K. The nature of the water present in two different PCC samples was investigated by thermal analyses (thermogravimetric and Karl Fischer analyses), Rietveld analyses on X-rays powder diffraction, infrared and Raman spectroscopies and solid state 1H MAS NMR. The second water release at about 725Â K was clearly identified as being portlandite dehydration. Ca(OH)2 was present in the PCC in an amorphous state. Its crystallization occurred simultaneously to the first water release at about 525Â K. Structural effects observed on calcite during the first water release led to the assignment to structural water molecules inserted in the structure of calcite.
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Materials Science
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Authors
G. Renaudin, A. Bertrand, M. Dubois, S. Gomes, P. Chevalier, A. Labrosse,