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XRD Measurement of Mean Crystallite Thickness of Illite and Illite/Smectite: Reappraisal of the Kubler Index and the Scherrer Equation

Published online by Cambridge University Press:  28 February 2024

Victor Drits ,
Jan Środoń  and
D. D. Eberl
Victor Drits
Affiliation:
Institute of Geology RAN, Pyzhevsky Street 7, 109017 Moscow, Russia
Jan Środoń
Affiliation:
Institute of Geological Sciences PAN, Senacka 1, 31002 Kraków, Poland
D. D. Eberl
Affiliation:
United States Geological Survey, 3215 Marine St., Boulder, Colorado 80303-1066
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Abstract

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The standard form of the Scherrer equation, which has been used to calculate the mean thickness of the coherent scattering domain (CSD) of illite crystals from X-ray diffraction (XRD) full width data at half maximum (FWHM) intensity, employs a constant, Ksh, of 0.89. Use of this constant is unjustified, even if swelling has no effect on peak broadening, because this constant is valid only if all CSDs have a single thickness. For different thickness distributions, the Scherrer “constant” has very different values.

Analysis of fundamental particle thickness data (transmission electron microscopy, TEM) for samples of authigenic illite and illite/smectite from diagenetically altered pyroclastics and filamentous illites from sandstones reveals a unique family of lognormal thickness distributions for these clays. Experimental relations between the distributions’ lognormal parameters and mean thicknesses are established. These relations then are used to calculate the mean thickness of CSDs for illitic samples from XRD FWHM, or from integral XRD peak widths (integrated intensity/maximum intensity).

For mixed-layer illite/smectite, the measured thickness of the CSD corresponds to the mean thickness of the mixed-layer crystal. Using this measurement, the mean thickness of the fundamental particles that compose the mixed-layer crystals can be calculated after XRD determination of percent smectitic interlayers. The effect of mixed layering (swelling) on XRD peak width for these samples is eliminated by using the 003 reflection for glycolated samples, and the 001, 002 or 003 reflection for dehydrated, K-sa-turated samples. If this technique is applied to the 001 reflection of air-dried samples (Kubler index measurement), mean CSD thicknesses are underestimated due to the mixed-layering effect.

The technique was calibrated using NEWMOD©-simulated XRD profiles of illite, and then tested on well-characterized illite and illite/smectite samples. The XRD measurements are in good agreement with estimates of the mean thickness of fundamental particles obtained both from TEM measurements and from fixed cations content, up to a mean value of 20 layers. Correction for instrumental broadening under the conditions employed here is unnecessary for this range of thicknesses.

Keywords

Crystal ThicknessIlliteIllite/SmectiteKubler IndexMixed-Layer CrystalsScherrer EquationXRD
Type
Research Article
Information
Clays and Clay Minerals , Volume 45 , Issue 3 , June 1997 , pp. 461 - 475
Copyright
Copyright © 1997, The Clay Minerals Society

References

Drits, V.A., Eberl, D.D. and Środoń, J.. 1997. XRD measurement of mean thickness, thickness distribution and strain for illite and illite/smectite crystallites by the Bertaut-Warren-Av-erboch technique. Clays Clay Miner 45: in press.CrossRefGoogle Scholar
Drits, V.A. and Tchoubar, C., (1990) X-Ray diffraction by disordered lamellar structures: Theory and applications to microdivided silicates and carbons New York Springer-Verlag 10.1007/978-3-642-74802-8.CrossRefGoogle Scholar
Drits, V.A. Varaxina, T.V. Sakharov, B.A. and Plançon, A., (1994) A simple technique for identification of one-dimensional powder X-ray diffraction patterns for mixed-layer illite/smectites and other interstratified minerals Clays Clay Miner 42 42–390 10.1346/CCMN.1994.0420402.CrossRefGoogle Scholar
Eberl, D.D. Środoń, J. Lee, M. Nadeau, P.H. and Northrop, H.R., (1987) Sericite from the Silverton caldera, Colorado: Correlation among structure, composition, origin, and particle thickness Am Mineral 72 914–934.Google Scholar
Eberl, D.D. Środoń, J. Kralik, M. Taylor, B.E. and Peterman, Z.E., (1990) Ostwald ripening of clays and metamorphic minerals Science 248 248–477 10.1126/science.248.4954.474.CrossRefGoogle Scholar
Frey, M. and Frey, M., (1987) Very low-grade metamorphism of clastic sedimentary rocks Low temperature metamorphism New York Blackie.Google Scholar
James, R.W.. 1965. The optical principles of the diffraction of X-rays. In: Bragg, L., editor. Crystalline state, vol. II, Ithaca, NY: Cornell Univ Pr. 664 p.Google Scholar
Kisch, H.J., Larsen, G. and Chilingar, G.V., (1983) Mineralogy and petrology of burial diagenesis (burial metamorphism) and incipient metamorphism in clastic rocks Diagenesis in sediments and sedimentary rocks 2 New York Elsevier.Google Scholar
Kisch, H.J. and Frey, M., (1987) Correlation between indicators of very lowgrade metamorphism Low temperature metamorphism New York Blackie.Google Scholar
Klug, H.P. and Alexander, L.E., (1974) X-ray diffraction procedures 2nd ed. New York J. Wiley.Google Scholar
Kubler, B., (1964) Les argiles, indicateurs de metamorphisme Rev Inst Fr Petrol 19 1093–1112.Google Scholar
Merriman, R.J. Roberts, B. and Peacor, D.R., (1990) A transmission electron microscope study of white mica crystallite size distribution in a mudstone to slate transitional sequence, North Wales, UK Contrib Mineral Petrol 106 27–40 10.1007/BF00306406.CrossRefGoogle Scholar
Moore, D.M. and Reynolds, R.C. Jr., (1989) X-ray diffraction and the identification and analysis of clay minerals New York Oxford Univ Pr..Google Scholar
Nadeau, P.H. Wilson, M.J. McHardy, W.J. and Tait, J.M., (1984) Interstratified clays as fundamental particles Science 225 225–925 10.1126/science.225.4665.923.CrossRefGoogle ScholarPubMed
Reynolds, R.C. Jr., (1985) NEWMOD©: A computer program for the calculation of one-dimensional patterns of mixed-layer clays Hanover, NH RC Reynolds Jr, 8 Brook Rd.Google Scholar
Środoń, J., (1980) Precise identification of illite/smectite interstratifications by X-ray powder diffraction Clays Clay Miner 28 28–411.CrossRefGoogle Scholar
Środoń, J., (1984) X-ray diffraction of illitic materials Clays Clay Miner 32 32–349 10.1346/CCMN.1984.0320501.CrossRefGoogle Scholar
Środoń, J. Andreolli, C. Elsass, F. and Robert, M., (1990) Direct high-resolution transmission electron microscopic measurement of expandability of mixed-layer illite/smectite in bentonite rock Clays Clay Miner 38 38–379 10.1346/CCMN.1990.0380406.CrossRefGoogle Scholar
Środoń, J. Eberl, D.D. and Drits, V.A., (1997) Evolution of crystal size during illitization of smectite Jurnees scientifiques en l’honneur de V. A. Drits 66–67.Google Scholar
Środoń, J. and Elsass, F., (1994) Effect of the shape of fundamental particles on XRD characteristics of illitic minerals Eur J Mineral 6 6–122 10.1127/ejm/6/1/0113.CrossRefGoogle Scholar
Środoń, J. Elsass, F. McHardy, W.J. and Morgan, D.J., (1992) Chemistry of illite-smectite inferred from TEM measurements of fundamental particles Clay Miner 27 27–158 10.1180/claymin.1992.027.2.01.CrossRefGoogle Scholar
Środoń, J. Morgan, D.J. Eslinger, E.V. Eberl, D.D. and Karlinger, M.R., (1986) Chemistry of illite/smectite and end-member illite Clays Clay Miner 34 34–378 10.1346/CCMN.1986.0340403.CrossRefGoogle Scholar
Weber, F. Dunoyer deSegonzac, G. and Economou, C., (1976) Une nouvelle expression de la ‘cristallinite’ de l’illite et des micas. Notion d’‘epaisseur apparente’ des cristallites CR Somm Soc Geol Fr. 5 5–227.Google Scholar