Clay profiling : The classification of montmorillonites
Emmerich, Katja (Forschungszentrum Karlsruhe. Competence Center for Material Moisture. University of Karlsruhe)
Wolters, Felicitas
Kahr, Guenter (ETH Zürich. Institute of Geotechnical Engineering)
Lagaly, Gerhard (University of Kiel. Institute of Inorganic Chemistry)

Fecha:	2009
Resumen:	Montmorillonites, with the general composition M (SiAl) [(Al,Fe) (Mg,Fe)] O(OH) where x = ξ = 0. 2a0. 6, x = y+z, and y«z, vary widely in composition and structure. The commonly used classification into five montmorilloniteand two beidellitegroups for the solid-solution sequence does not allow an unambiguous classification with respect to structural features and the resulting properties. The smectite structure reveals five features that allow an unambiguous description of a sample: (1) identification as either a dioctahedral or a trioctahedral smectite; (2) layer charge; (3) charge distribution between tetrahedral and octahedral sheets; (4) cation distribution within the octahedral sheet; and (5) Fe content. In addition, the nature of interlayer cations should be given as they influence certain properties of montmorillonites. Analytical methods are now available to measure and determine these structural features. Therefore, a precise classification for montmorillonites requires determination of layer charge and exchangeable cations, analysis of chemical composition, and thermal analysis (to determine the octahedral structure), in addition to X-ray diffraction analysis. A comprehensive classification of montmorillonites based on these parameters is proposed. Ninety-six structural variations (expressed by systematic names) theoretically exist within the montmorillonite-beidellite series. Descriptive names can be used to elucidate the macroscopic properties of the montmorillonite samples in question.
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Layer Silicates ; Cis-vacant ; Classification ; Dioctahedral ; Layer Charge ; Montmorillonite ; Smectite ; Trans-vacan
Publicado en:	Clays and Clay Minerals, Vol. 57, Núm. 1 (2009) , p. 104-114, ISSN 1552-8367

DOI: 10.1346/CCMN.2009.0570110

11 p, 161.0 KB  Acceso restringido a la UAB

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