Stacking disorder in a sedimentary kaolinite
Kogure, Toshihiro (The University of Tokyo. Department of Earth and Planetary Science)
Elzea-Kogel, Jessica (IMERYS)
Johnston, Cliff T. (Purdue University. Crop, Soil and Environmental Sciences)
Bish, David L. (Indiana University. Department of Geological Sciences)

Data:	2010
Resum:	Although structural disorder in kaolinite has been investigated extensively, it is still not understood properly. To investigate the problem, a kaolinite specimen of sedimentary origin from Capim, Brazil, was examined, mainly by transmission electron microscopy (TEM). Selected-area electron diffraction (SAED) along the X ([100], [110], and [110]) directions shows various features, from completely discrete patterns to heavily streaked ones along the c* direction, suggesting that the degree of stacking disorder is variable among individual grains. High-resolution TEM images indicate that stacking faults are mainly caused by disorder of alternating t (~-a/3) and t (-a/3 +6/3) layer displacements. Furthermore, stacking faults have been observed (1) as isolated stacking faults (e. g. insertion of an isolated t 'fault' in an ordered sequence with t layer displacement) and (2) as interstratification of two kinds of multilayer blocks having regular t and t layer displacements. A mixture of grains with various degrees and modes of disorder with alternating t and t layer displacements may explain the experimental profile of the 02, 11 X-ray diffraction band. Faults related to displacement of the octahedral vacancy and/or to layer rotation were also observed in HRTEM images. The SAED patterns along the Y ([010], [310], and [310]) directions occasionally have extra spots and/or streaks, suggesting the presence of stacking sequences with (±60°, 180°) mutual layer rotation and/or with (0, ±6/3) layer displacements. The local dickite or nacrite-like fragments formed by these faults are in qualitative agreement with recent low-temperature FTIR results from this sample, where distinct v(OH) absorption bands reflect multiple interlayer O-H···O environments that are possibly ascribed to dickite and nacrite.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	FTIR ; HRTEM ; Kaolinite ; SAED ; Stacking Fault
Publicat a:	Clays and Clay Minerals, Vol. 58, Núm. 1 (2010) , p. 62-71, ISSN 1552-8367

DOI: 10.1346/CCMN.2010.0580106

10 p, 1.7 MB  Accés restringit a la UAB

El registre apareix a les col·leccions:
Articles > Articles de recerca
Articles > Articles publicats