Geologica Belgica

1374-8505 2034-1954

 

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J. Theo KLOPROGGE & Ray L. FROST

Infrared emission spectroscopy study of the dehydroxylation of 10 Å halloysite from a Neogene cryptokarst of South Belgium

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Mots-clés : Belgium, KEYWORDS: halloysite, infrared emission spectroscopy, dehydroxylation, metahalloysite, hydrated kaolinite, cryptokarst

Abstract

ABSTRACT. The dehydroxylation of 10 À halloysite from the Wellin (Weillen) cryptokarst (southern Belgium) was studied in situ by applying infrared emission spectroscopy. Dehydroxylation is evidenced by the loss of the OH-stretching modes between 3600 and 3700 cm-1. A slow decrease of all intensities up to ± 500°C is observed followed between 500° and 550°C by a rapid decrease to almost zero. The IES bands at 920 and 938 cm-1, attributed to the accompanying inner and outer or inner sheet Al-OH libration modes, are removed on heating at the same rate and disappears at the same temperature as the OH-stretching bands. The low frequency bands that disappear upon heating are associated with OH-libration (920 and 938 cm-1) or OH-translation modes (798, 754 and 693 cm-1). At high temperatures only very broad bands around 800 cnr', a weak shoulder around 900 cnr' and two broad bands around 1000 and 1175 cm-1 are observed. The first two are associated with newly formed Al-O bonds whereas the other two are associated with Si-0 bonds in the dehydroxylated halloysite, an X-ray amorphous mullite-like phase.

To cite this article

J. Theo KLOPROGGE & Ray L. FROST, «Infrared emission spectroscopy study of the dehydroxylation of 10 Å halloysite from a Neogene cryptokarst of South Belgium», Geologica Belgica [En ligne], number 3-4, volume 2 (1999), 55-62 URL : http://popups.ulg.ac.be/1374-8505/index.php?id=1805.

About: J. Theo KLOPROGGE

Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane Qld 4001, Australia, t.kloprogge@qut.edu.au

About: Ray L. FROST

Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane Qld 4001, Australia,