Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Supplementary Data Info Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Post, J. E. Articles by Heaney, P. J. Search for Related Content GeoRef GeoRef Citation

Synchrotron powder X-ray diffraction study of the structure and dehydration behavior of sepiolite

¹ Department of Mineral Sciences, Smithsonian Institution, Washington, D.C. 20560-0119, U.S.A.
² Department of Geological Sciences, Indiana University, Bloomington, Indiana 47405-1405, U.S.A.
³ Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, U.S.A.

Correspondence: ^* E-mail: postj{at}si.edu

Rietveld refinements using synchrotron powder X-ray diffraction data were used to study the crystal structure and dehydration behavior of sepiolite from Durango, Mexico. The room-temperature (RT) sepiolite structure in air compares well with previous models but reveals an additional zeolitic H₂O site. The RT structure under vacuum retained only ~1/8 of the zeolitic H₂O and the volume decreased by 1.3%. Real-time, temperature-resolved synchrotron powder X-ray diffraction data and Rietveld refinements were used to investigate the behavior of the sepiolite structure from 300 to 925 K. Rietveld refinements revealed that most of the zeolitic H₂O is lost by ~390 K, accompanied by a decrease in the a and c unit-cell parameters. Above ~600 K the sepiolite structure folds as one-half of the crystallographically bound H₂O is lost. Rietveld refinements of the "anhydrous" sepiolite structure reveal that, in general, unit-cell parameters a and b and volume steadily decrease with increasing temperature; there is an obvious change in slope at ~820 K suggesting a phase transformation coinciding with the loss of the remaining bound H₂O molecule.

Key Words: Sepiolite • Rietveld • synchrotron • powder diffraction

This article has been cited by other articles:

				J. E. Post and P. J. Heaney Synchrotron powder X-ray diffraction study of the structure and dehydration behavior of palygorskite American Mineralogist, April 1, 2008; 93(4): 667 - 675. [Abstract] [Full Text] [PDF]

				V. Gionis, G. H. Kacandes, I. D. Kastritis, and G. D. Chryssikos COMBINED NEAR-INFRARED AND X-RAY DIFFRACTION INVESTIGATION OF THE OCTAHEDRAL SHEET COMPOSITION OF PALYGORSKITE Clays and Clay Minerals, December 1, 2007; 55(6): 543 - 553. [Abstract] [Full Text] [PDF]