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Raman and X-ray Diffraction Data on Anatase in Fired Kaolins

Published online by Cambridge University Press:  01 January 2024

Enver Murad
Enver Murad*
Affiliation:
Bayerisches Geologisches Landesamt, Leopoldstrasse 30, D-95603 Marktredwitz, Germany
*
*E-mail address of corresponding author: [email protected]
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Abstract

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The Raman spectra of many kaolins are dominated by bands from ancillary anatase. Fired samples of a commercial anatase-bearing kaolin from the Jari River deposit in Brazil showed significant variations of Raman spectra as a function of the firing temperature. The spectra showed the full range of anatase bands up to a firing temperature of 900°C. From 950°C the background increased significantly, leading to an unfavorable signal/noise ratio that allowed observation of only the most intense (Eg) band at ~144 cm−1. X-ray diffraction (XRD), however, confirmed that this band, which persists up to 1200°C, results from anatase. Two factors may be responsible for the high thermal stability of anatase in this sample: its relatively large particle size of ~120 nm and possible reactions with Si and Al that become liberated during kaolinite breakdown. When evaluated with circumspection, Raman and XRD data on anatase can serve as ‘thermometers’ to elucidate the thermal history of fired anatase-bearing kaolins and other anatase-bearing clays.

Keywords

AnataseFiringKaoliniteRaman SpectroscopyX-ray Diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 51 , Issue 6 , December 2003 , pp. 689 - 692
Copyright
Copyright © 2003, The Clay Minerals Society

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