Cation mass-valence sum (CM-VS) approach to assigning OH-bending bands in dioctahedral smectites
Gates, Will (Monash University. Department of Civil Engineering)

Fecha:	2008
Resumen:	The assignments of OH-bending bands in the infrared (IR) spectra of dioctahedral smectites (montmorillonites, ferruginous smectites, and nontronites) have been revisited using a cation mass-valence sum (CM-VS) approach to quantify octahedral cation occupancy. The CM-VS approach enabled prediction of OH-bending band positions (in wavenumbers) related to OH-sharing octahedral cation pairs that had valence sums of 4 and 5, and cation masses associated with Fe(II) and Mg. Application of rules for the relationship enabled determination of the location of OH-sharing octahedral cation pairs containing Mg and Fe(II) for which previous assignments have been considered controversial, e. g. Fe(III)Mg-OH and MgMg-OH, or for which assignments have been missing due to lack of spectroscopic evidence, e. g. AlFe(II)-OH, Fe(III)Fe(II)-OH, Fe(II)Mg-OH, and Fe(II)Fe(II)-OH. Examples of these bands from several natural ferruginous smectites and nontronites are discussed. Quantification of IR spectra was used to develop a better understanding of the octahedral cation occupancy of this important class of Fe(III)-enriched smectites. While Fe(II) contents may be somewhat overestimated by the IR technique, those for four of the six ferruginous smectites studied here agree well with data from Mössbauer spectroscopy.
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Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Cation mass ; Cation pairs ; Infrared spectroscopy ; Octahedral ; Smectite chemistry ; Valence sum
Publicado en:	Clays and Clay Minerals, Vol. 56, Núm. 1 (2008) , p. 10-22, ISSN 1552-8367

DOI: 10.1346/CCMN.2008.0560102

13 p, 1.8 MB  Acceso restringido a la UAB

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