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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

References

Dachille, F. Simons, P.Y. and Roy, R., (1968) Pressuretemperature studies of anatase, brookite, rutile and TiO2-II American Mineralogist 53 1929–1939.Google Scholar
Gribb, A.A. and Banfield, J.F., (1997) Particle size effects on transformation kinetics and phase stability in nanocrystalline TiO2 American Mineralogist 82 717–728 10.2138/am-1997-7-809.Google Scholar
Heald, E.F. and Weiss, C.W., (1972) Kinetics and mechanism of the anatase/rutile transformation, as catalyzed by ferric oxide and reducing conditions American Mineralogist 57 10–23.Google Scholar
Lindsley, D.H. and Lindsley, D.H., (1991) Experimental studies of oxide minerals Oxide Minerals: Petrologic and Magnetic Significance Washington, D.C. Mineralogical Society of America 69–106 10.1515/9781501508684-006.Google Scholar
Lottici, P.P. Bersani, D. Braghini, M. and Montenero, A., (1993) Raman scattering characterization of gel-derived titania glass Journal of Materials Science 28 177–183 10.1007/BF00349049.Google Scholar
Murad, E., (1997) Identification of minor amounts of anatase in kaolins by Raman spectroscopy American Mineralogist 82 203–206 10.2138/am-1997-1-222.Google Scholar
Murad, E. and Köster, H.M., (1999) Determination of the Ti speciation in commercial kaolins by Raman spectroscopy Clay Minerals 34 479–485 10.1180/000985599546389.Google Scholar
Murad, E. and Wagner, U., (1991) Mössbauer spectra of kaolinite, halloysite and the firing products of kaolinite: new results and a reappraisal of published work Neues Jahrbuch für Mineralogie Abhandlungen 162 281–309.Google Scholar
Murray, H.H. and Partridge, P., (1982) Genesis of Rio Jari kaolin Proceedings of the International Clay Conference Bologna-Pavia 35 279–291.Google Scholar
Stanjek, H. and Friedrich, R., (1986) The determination of layer charge by curve-fitting of Lorentz- and polarization-corrected X-ray diagrams Clay Minerals 21 183–190 10.1180/claymin.1986.021.2.07.Google Scholar
Yang, J. and Ferreira, J.M.F., (1998) Inhibitory effect of the Al2O3−SiO2 mixed additives on the anatase-rutile phase transformation Materials Letters 36 320–324 10.1016/S0167-577X(98)00042-1.Google Scholar
Zhang, H. and Banfield, J.F., (1999) New kinetic model for the nanocrystalline anatase-to-rutile transformation rate revealing dependence on number of particles American Mineralogist 84 528–535 10.2138/am-1999-0406.Google Scholar