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Rietveld Refinement of Non-Hydrogen Atomic Positions in Kaolinite

Published online by Cambridge University Press:  02 April 2024

D. L. Bish  and
R. B. Von Dreele
D. L. Bish
Affiliation:
Earth and Space Sciences Division, Los Alamos, New Mexico 87545
R. B. Von Dreele
Affiliation:
Los Alamos Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
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Abstract

The structure of kaolinite (non-hydrogen atoms only) from Keokuk, Iowa, was refined in space group C1 using CuKα X-ray powder diffraction data and Rietveld refinement techniques (Rwp = 12.3%). A distance least-squares (DLS) model for the initial atomic coordinates avoided a false minimum and unrealistic results characteristic of previous Rietveld refinements of kaolinite. All Keokuk samples examined contain small amounts of dickite. The profile of the mixture was calculated using a fixed set of dickite atomic parameters and by constraining the dickite profile parameters to those refined for kaolinite. Results indicate that the individual kaolinite layer is very similar to the dickite layer; bond distances, which are similar to dickite and nacrite, are: Si-O, 1.60-1.63 Å; Al-O, 1.87-1.97 Å. The tetrahedral rotation angle is 6.9°, compared with 7.3° for dickite and 7.4° for nacrite. Previous Rietveld refinements apparently suffered from poor preferred orientation models, failure to consider the presence of dickite as a second phase, and, most importantly, refinement to a false-minimum structure. The conclusions based on the earlier refinements must therefore be reevaluated, especially regarding the kaolinite space group and hydrogen positions. Existing X-ray and electron diffraction and spectroscopic data support the presence of C-centering in kaolinite.

Keywords

Crystal structureDickiteKaoliniteRietveld refinementX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 37 , Issue 4 , August 1989 , pp. 289 - 296
Copyright
Copyright © 1989, The Clay Minerals Society

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References

Adams, J. M., 1983 Hydrogen atom positions in kaolinite by neutron profile refinement Clays & Clay Minerals 31 352 – 356.CrossRefGoogle Scholar
Bailey, S. W., 1963 Polymorphism of the kaolin minerals Amer. Mineral. 48 1196 – 1209.Google Scholar
Bailey, S. W., Brindley, G. W. and Brown, G., 1980 Structures of layer silicates Crystal Structures of Clay Minerals and their X-ray Identification London Mineralogical Society 1 – 123.Google Scholar
Blount, A. M., Threadgold, I. M. and Bailey, S. W., 1969 Refinement of the crystal structure of nacrite Clays & Clay Minerals 17 185 – 194.CrossRefGoogle Scholar
Brindley, G. W., Kao, C.-C. Harrison, J. L., Lipsicas, M. and Raythatha, R., 1986 Relation between structural disorder and other characteristics of kaolinites and dickites Clays & Clay Minerals 34 239 – 249.CrossRefGoogle Scholar
Brindley, G. W. and Nakahira, M., 1958 Further consideration of the crystal structure of kaolinite Mineral Mag. 31 781 – 786.Google Scholar
Brindley, G. W. and Robinson, K., 1946 The structure of kaolinite Mineral. Mag. 27 242 – 253.Google Scholar
Deslattes, R. D. and Henins, A., 1973 X-ray to visible wavelength ratios Phys. Rev. Letters 31 972 – 975.CrossRefGoogle Scholar
Dollase, W.A., 1986 Correction of intensities for preferred orientation in powder diffractometry: Application of the March model J. Appl. Crystallogr. 19 267 – 272.CrossRefGoogle Scholar
Drits, V. A. and Kashaev, A. A., 1960 An X-ray study of a single crystal of kaolinite Soviet Phys. Crystallogr. 5 207 – 210.Google Scholar
Greaves, C., 1985 Rietveld analysis of powder neutron diffraction data displaying anisotropic crystallite size broadening J. Appl. Crystallogr. 18 48 – 50.CrossRefGoogle Scholar
Hayes, J. B., 1963 Kaolinite from Warsaw geodes, Keokuk region, Iowa Iowa Acad. Sci. 70 261 – 272.Google Scholar
Hill, R. J. and Madsen, I. C., 1984 The effect of profile step counting time on the determination of crystal structure parameters by X-ray Rietveld analysis J. Appl. Crystallogr. 17 297 – 306.CrossRefGoogle Scholar
Joswig, W. and Drits, V. A., 1986 The orientation of the hydroxyl groups in dickite by X-ray diffraction N. Jb. Miner. Mh. 1986 19 – 22.Google Scholar
Keller, W. D., 1988 Authigenic kaolinite and dickite associated with metal sulfides—probable indicators of a regional thermal event Clays & Clay Minerals 36 153 – 158.CrossRefGoogle Scholar
Larson, A. C. and Von Dreele, R. B. (1988) Generalized structure analysis system: Los Alamos National Laboratory Kept. LAUR 86–748, 150 pp.Google Scholar
Lee, J. H. and Guggenheim, S., 1981 Single crystal X-ray refinement of pyrophyllite-1 Tc Amer. Mineral. 66 350 – 357.Google Scholar
Mansfield, C. F. and Bailey, S. W., 1972 Twin and pseudotwin intergrowths in kaolinite Amer. Mineral. 57 411 – 425.Google Scholar
Meier, W. M. and Villiger, H., 1969 Die Methode der Abstandsvergeinerung zur Bestimmung der Atomkoordinaten idealisierter Gerustrukturen Z. Kristallogr. 129 411 – 423.CrossRefGoogle Scholar
Newnham, R.E., 1961 A refinement ofthe dickite structure and some remarks on polymorphism in kaolin minerals Mineral. Mag. 32 683 – 704.Google Scholar
Pauling, L., 1930 The structure of the chlorites Proc. Natl. Acad. Sci., U.S.A. 16 578 – 582.CrossRefGoogle ScholarPubMed
Plançon, A. and Giese, R. F. Jr., 1988 The Hinckley index does not measure the “crystallinity” of kaolinites Prog, and Absts., 25th Annual Meeting of the Clay Minerals Society Michigan Grand Rapids 40 (available from The Clay Minerals Society, P.O. Box 2295, Bloomington, Indiana 47402).Google Scholar
Rietveld, H. M., 1969 Profile refinement method for nuclear and magnetic structures J. Appl. Crystallogr. 2 65 – 71.CrossRefGoogle Scholar
Smyth, J. R. and Bish, D. L., 1988 Crystal Structures and Cation Sites of the Rock-Forming Minerals Boston Allen and Unwin.Google Scholar
Suitch, P. R. and Young, R. A., 1983 Atom positions in well-ordered kaolinite Clays & Clay Minerals 31 357 – 366.CrossRefGoogle Scholar
Thompson, J. G. and Withers, R. L., 1987 A transmission electron microscopy contribution to the structure of kaolinite Clays & Clay Minerals 35 237 – 239.CrossRefGoogle Scholar
Thompson, P., Cox, D. E. and Hastings, J. B., 1987 Rietveld refinement of Debye-Scherrer synchrotron X-ray data from Al2O3 J. Appl. Crystallogr. 20 79 – 83.CrossRefGoogle Scholar
Villiger, H., 1969 DLS. A FORTRAN Computer Program for the Least-Squares Refinement of Interatomic Distances Switzerland Institut für Kristallographie und Petrographie, ETH, Zurich.Google Scholar
Young, R. A. and Hewat, A. W., 1988 Verification of the triclinic crystal structure ofkaolinite Clays & Clay Minerals 36 225 – 232.CrossRefGoogle Scholar
Zvyagin, B. B., 1960 Electron diffraction determination of the structure ofkaolinite Kristallografiya 5 32 – 41.Google Scholar