Disorder and Dynamics in Pollucite from 133Cs and 27Al NMR
Abstract:Pollucite, CsAlSi2O6, a Cs polymorph of leucite (KAlSi2O6), has been proposed for ceramic immobilization of 135Cs and 137Cs fission products. 133Cs NMR of both low- (tetragonal) and high-temperature (cubic) forms of pollucite exhibit a considerable distribution of local Cs environments. 29Si and 27Al NMR data from directly prepared pollucite show greater Al/Si disorder than either leucite, or pollucite produced by ion exchange. Little evidence for Cs motion is observed in tetragonal or cubic pollucite, and only at high temperatures (∼850°C) is any substantial dynamic behavior detected. Dynamic NMR lineshape calculations allow a determination of the frequency of Cs motion and diffusivity.
Document Type: Research Article
Affiliations: Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, U.K.
Publication date: June 1, 2005