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A neutron diffraction study of alkali cation migration in montmorillonites |
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| Authors: | D Gournis A Lappas M A Karakassides D Többens A Moukarika |
| Institution: | (1) Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece;(2) Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 71110 Heraklion, Greece;(3) Berlin Neutron Scattering Center, Hahn-Meitner-Institüt, Glienicker Strasse 100, D-14109 Berlin, Germany;(4) Department of Physics, University of Ioannina, 45110 Ioannina, Greece |
| Abstract: | Neutron powder diffraction measurements on lithium and cesium saturated montmorillonite samples before and after heat treatment at 300°C are studied, in order to undertake a complete refinement of crystal structure and unravel the migration mechanism for the interlayer cations of Li or Cs. Rietveld analysis of the corresponding diffraction patterns finds that montmorillonite crystallizes in the C2/m space group with unit cell dimensions consistent with the size of the specific interlayer cation. We show that thermal treatment affects the two types of samples in a different way. This is with respect to their unit cell dimensions and the migration of Li from the 2b to the 2c clay lattice site, in constrast to the Cs positioning which remains effectively unchanged. |
| Keywords: | Montmorillonite Neutron diffraction Lithium migration Infrared reflectance Hoffman Klemen effect |
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