Interpretation of Infrared Spectra of Oxidized and Reduced Nontronite
- 1 December 1976
- journal article
- Published by Cambridge University Press (CUP) in Clays and Clay Minerals
- Vol. 24 (6) , 293-296
- https://doi.org/10.1346/ccmn.1976.0240604
Abstract
Infrared spectra of nontronite reveal shifts to lower wave, number in peaks located at 3570, 1030, and 821 cm-1, which are assigned to vibrational modes for O-H stretching, Si-Ob (basal oxygens) tetrahedral vibrations, and FeO-H deformation, respectively, as the Fe2+ content increases upon reduction. A pleochroic shoulder at 1110 cm-1 resulting from Si-Oa (apical oxygens) interactions appears to be unchanged with reduction. The absorption band at 848 cm-1 shifts to higher energy with reduction of structural iron, and persists at 840 cm-1 after complete deuteration of structural hydroxyls. The band is assigned to a Fe-OH mode where the OH moves as a unit. The shift in the Si-Ob mode to lower vibrational energy with reduction may indicate a decrease in stress forces between the tetrahedral and octahedral sheets.Keywords
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