Increase of ionic conductivity in the microporous lithosilicate RUB-29 by Na-ion exchange processes
- Material- and Earth Sciences, Technische Universitaet Darmstadt, Petersenstr. 23, 64287 Darmstadt (Germany)
- Mineralogisch-Petrographisches Institut, Universitaet Hamburg, Grindelallee 48, 20146 Hamburg (Germany)
The ionic conductivity in the zeolite-like lithosilicate RUB-29 (Cs{sub 14}Li{sub 24}[Li{sub 18}Si{sub 72}O{sub 172}].14H{sub 2}O [S.-H. Park, J.B. Parise, H. Gies, H. Liu, C.P. Grey, B.H. Toby, J. Am. Chem. Soc. 122 (2000) 11023-11024]) increases via simple ion-exchange processes, in particular when Na cations replace a part of Cs{sup +} and Li{sup +} of the material. The resulting ionic conductivity value of 3.2x10{sup -3} S cm{sup -1} at 885 K is about two orders higher than that for the original material [S.-H. Park, J.B. Parise, M.E. Franke, T. Seydel, C. Paulmann, Micropor. Mesopor. Mater., in print ( (doi:10.1016/j.micromeso.2007.03.040) available online since April 19, 2007)]. The structural basis of a Na{sup +}-exchanged RUB-29 sample (Na-RUB-29) at 673 K could be elucidated by means of neutron powder diffraction. Rietveld refinements confirmed the replacement of Na{sup +} for both parts of Cs and Li cations, agreeing with idealized cell content, Na{sub 8}Cs{sub 8}Li{sub 40}Si{sub 72}O{sub 172}. As a result of the incorporation of Na{sup +} in large pores, the number of Li{sup +} vacancies in dense Li{sub 2}O-layers of the structure could increase. This can be one of the main reasons for the improved conductivity in Na-RUB-29. In addition, mobile Na cations may also contribute to the conductivity in Na-RUB-29 as continuous scattering length densities were found around the sites for Na in difference Fourier map. - Graphical abstract: Li{sub 2}O-layers formed by edge- and corner-sharing LiO{sub 4}- and LiO{sub 3}-moieties in the zeolite-like lithosilicate RUB-29 provide optimal pathways for conducting Li{sup +}. The number of empty Li sites in this layer-like configuration could increase via 'simple' Na{sup +}-exchange processes, promoting fast Li motions.
- OSTI ID:
- 21043764
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 12; Other Information: DOI: 10.1016/j.jssc.2007.09.026; PII: S0022-4596(07)00396-9; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
Similar Records
INTEGRATED GENOME-BASED STUDIES OF SHEWANELLA ECOPHYSIOLOGY
A new class of non-zeolitic sorbents for air separations: Lithium ion exchanged pillared clays