Evidence for the multiphase nature of bentonites from Mössbauer and EPR spectroscopy

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Authors:Goodman, Bernard A.; Nadeau, P. H.; Chadwick, J.
Author Affiliations:Primary:
Macaulay Land Use Res. Inst., Aberdeen, Scotland, United Kingdom
Other:
Univ. Liverpool, United Kingdom
Volume Title:Clay Minerals
Source:Clay Minerals, 23(2), p.147-159. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1988
Note:In English. 28 refs.; illus. incl. 4 tables
Summary:Mössbauer spectra of several smectites demonstrate the existence of at least three phases with distinct Fe populations: (i) a component with very low Fe content (< 1%), which shows slowly-relaxing paramagnetic hyperfine structure at both 4·2 K and 77 K; (ii) a component with intermediate Fe content (∼ 1-10%) which is seen as doublets in the spectra at 4·2 K, 77 K and ambient temperature; (iii) an Fe-rich phase (> 30% Fe), which shows magnetic ordering at 4·2 K and 77 K. These data are consistent with components (i) and (ii) corresponding to Fe incorporated in aluminosilicate structures from distinct phases, whereas (iii) is characteristic of an iron oxide phase, probably goethite in most cases. These conclusions are supported by EPR measurements which show magnetically-dilute Fe in more than one type of structural environment plus an additional component with magnetically-interacting ions. [R.A.H.]
Subjects:Analysis; Bentonite; Clastic rocks; Clay mineralogy; Clay minerals; EPR spectra; Experimental studies; Mineral data; Mineralogy; Minerals; Mossbauer spectra; Sedimentary rocks; Sheet silicates; Silicates; Spectra; Spectroscopy
Abstract Numbers:89M/1567
Record ID:1989001671
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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