1. Crystal structure of magnesium silicate hydrates (M-S-H): The relation with 2:1 Mg–Si phyllosilicates
- Author
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Pierre Henocq, Eric Giffaut, Cédric Roosz, Barbara Lothenbach, Philippe Blanc, Sylvain Grangeon, Stéphane Gaboreau, Valérie Montouillout, Philippe Vieillard, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Swiss Federal Laboratories for Materials Science and Technology [Thun] (EMPA), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC)
- Subjects
Materials science ,Hydration products (B) ,Silicon ,Analytical chemistry ,chemistry.chemical_element ,Mineralogy ,02 engineering and technology ,Electron microprobe ,Crystal structure ,Silica fume (D) ,010502 geochemistry & geophysics ,01 natural sciences ,[SPI.MAT]Engineering Sciences [physics]/Materials ,chemistry.chemical_compound ,Crystal structure (B) ,General Materials Science ,0105 earth and related environmental sciences ,MgO (D) ,Magnesium ,Building and Construction ,021001 nanoscience & nanotechnology ,Silicate ,Nanocrystalline material ,chemistry ,X-ray crystallography ,Crystallite ,X-ray diffraction (B) ,0210 nano-technology - Abstract
International audience; Two magnesium silicate hydrates (M-S-H) with structural magnesium/silicon ratios of 0.57 ± 0.08 and 1.07 ± 0.13 were synthesized at room temperature, with one year of synthesis duration. Their structure was clarified by considering results from X-ray diffraction, TEM, 29Si MAS NMR spectroscopy, TGA, and EPMA. A modeling approach appropriate to defective minerals was used because usual XRD refinement techniques cannot be used in the case of turbostratic samples, where coherency between successive layers is lost. M-S-H with Mg/Si ratio of ~ 0.6 appears to be structurally close to nanocrystalline turbostratic 2:1 Mg–Si phyllosilicates. The increase of the Mg/Si ratio from 0.6 to 1.2 occurs by increasing the occurrence of defects in the silicate plan. The layer-to-layer distance evolves from 9.46 Å to 14 Å under air-dried and ethylene glycol conditions, respectively. Crystallites have a mean size of 1.5 nm in the ab plane, and 2.4 nm along c*.
- Published
- 2015
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