Skip to Main Content
Skip Nav Destination
GEOREF RECORD

The crystal chemistry of Al-bearing goethites; an infrared spectroscopic study

A. J. Blanch, J. s. Quinton, C. E. Lenehan and Allan Pring
The crystal chemistry of Al-bearing goethites; an infrared spectroscopic study
Mineralogical Magazine (October 2008) 72 (5): 1043-1056

Abstract

Aluminium substitution into goethite, alpha -FeOOH, has been studied systematically by infrared spectroscopy over the frequency interval 150 to 700 cm (super -1) . A range of synthetic compositions, (Fe (sub 1-x) Al (sub x) )OOH, 0< or =chi < or =0.0857, plus end-member diaspore (AlOOH) were examined. The IR spectrum of FeOOH over the range of interest can be deconvoluted into 9 peaks: 670, 633, 497, 451, 409, 396, 360, 290 and 268 cm (super -1) . With addition of Al, the spectra become broader and the frequencies of the modes shift to higher values. An effective line width parameter Delta (sub corr) was determined by autocorrelation analysis for each spectrum and there is a significant increase in the Delta (sub corr) for compositions with >5.85 mol.% Al substitution, indicating that there is very significant structural strain associated with this solid solution at compositions where a significant number of Al sites will have an additional Al atom in the first cation coordination sphere. Trends in the values of Delta (sub corr) with composition mirrored published enthalpy of mixing values indicating that Al-goethite is metastable with respect to the goethite and diaspore end-members. The role of substitutional strain and possible partial order of Al is briefly discussed.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 72
Serial Issue: 5
Title: The crystal chemistry of Al-bearing goethites; an infrared spectroscopic study
Affiliation: Flinders University, School of Chemistry, Physics and Earth Sciences, Adelaide, South Aust., Australia
Pages: 1043-1056
Published: 200810
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 29
Accession Number: 2010-023215
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Secondary Affiliation: South Australian Museum, AUS, Australia
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201014
Close Modal

or Create an Account

Close Modal
Close Modal