Infra-red Spectra of High-temperature Phases of Kaolinite and Halloysite

KAOLINITE and halloysite in the temperature-range 650–900° C. do not show any pronounced X-ray interference. In this range metakaolinite is formed; its Si—O hexagonal network remains more or less unchanged, while the octahedral sheet is deformed in absence of OH-groups 1,2 . In kaolinite and halloys...

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Bibliographic Details
Published in:Nature (London) 1957-01, Vol.179 (4558), p.542-542
Main Authors: STUBI AN, V, GÜNTHARD, HS. H
Format: Article
Language:English
Subjects:
Humanities and Social Sciences
letter
multidisciplinary
Science
Science (multidisciplinary)
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Summary:KAOLINITE and halloysite in the temperature-range 650–900° C. do not show any pronounced X-ray interference. In this range metakaolinite is formed; its Si—O hexagonal network remains more or less unchanged, while the octahedral sheet is deformed in absence of OH-groups 1,2 . In kaolinite and halloysite, dehydration brings about a random arrangement in the direction of the c -axis. In pure and perfectly crystallized kaolinite, heated in the differential thermal apparatus at a velocity of 10 deg. C. per min. just above the exothermal maximum, X-ray examination reveals γA1 2 O 3 and mullite, whereas in halloysite only γ-alumina appears. In halloysite heated in the same way, mullite is observed 3 only above 1,100° C. As the X-ray diagrams of mullite and sillimanite resemble each other closely, it is not certain which of these two phases is formed during the heating of kaolinite and halloysite.
ISSN:0028-0836
1476-4687
DOI:10.1038/179542a0