Dear Ana, Generally, as many of the contributors of this list said, smectites are only partly crystallised (sometimes turbostratic). Means you may observe nice 00L peaks, and diffusion bands along HK0 lines. These latters should be approached using appropriate formalism, actually I think not implemented in usual programs. You could find out how this formalism works, reading Dritz and Tchoubar books on the subject. On perfect powders, we (I and A. Manceau and B. Lanson in Grenoble, LGIT) could simulate diagrams like this using their formalism, taking account of bimodal compositional faults. Now on top of this, as in our case, a strong preferred orientation is also present in the sample. In these cases, we found useful to combine polarised EXAFS experiments with Quantitative Texture Analysis in order to sort out structural details. Please see on my personal web page, I have placed pdf files on this subject. daniel Quantitative Texture Analysis Internet Course: http://pecdc.univ-lemans.fr/qta/ ---------------------------------------------------------------------------- -------------------------------------------------- Daniel Chateigner LPEC, UMR-CNRS 06087, Université du Maine-Le Mans http://pecdc.univ-lemans.fr/lpec.html av. O. Messiaen, BP535 72085 Le Mans cedex Tel prof: 33 (0) 243833268 Fax: 33 (0) 243833518 http://www.univ-lemans.fr/~dchat/danielc/daniel.htm ---------------------------------------------------------------------------- --- ------------------- World Directory of Crystallographers and concerned scientists --------- fill the form at: http://www.univ-lemans.fr/~dchat/wdc10/state.htm A web-based "Powder Structure Determination" course: http://sdpd.univ-lemans.fr/course/ ---------------------------------------------------------------------------- --------------------------------------------
