Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.6: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

Investigation of Li dynamics in gas-phase synthesized amorphous oxides by NMR and impedance spectroscopy — •Viktor Epp, Christian Brünig, Martin Wilkening, Michael Binnewies, and Paul Heitjans — Leibniz Universität Hannover, D-30167 Hannover

Currently, great effort is put into finding novel ion conductors that meet the requirements of modern energy storage systems. The characterization of their transport properties with complementary methods plays a crucial role in this research area. Here, metastable, highly non-stoichiometric oxides containing Al, Li and Si were studied by impedance spectroscopy (IS) and, complementarily, by various ⁷Li NMR techniques which are capable to probe Li dynamics on different time and length scales [1, 2]. The samples, which are X-ray amorphous, were synthesized via a gas-phase reaction [3] from AlCl₃, LiCl and SiCl₄. The applied NMR techniques included the analysis of ⁷Li NMR spin-alignment echoes, line shapes as well as spin-lattice relaxation (SLR) rates T_1ρ⁻¹ in the rotating frame of reference. When probed on the same time scale, good agreement is found between the activation energies obtained from IS and SLR NMR. Altogether, the Li diffusivity in the investigated oxide turned out to be rather slow.

1.4em -1.4em [1] M. Wilkening, V. Epp, A. Feldhoff, P. Heitjans, J. Phys. Chem. C 112 (2008) 9291.

[2] M. Wilkening, P. Heitjans, Phys. Rev. B 77 (2008) 024311.

[3] T. Giesenberg, S. Hein, M. Binnewies, G. Kickelbick, Angew. Chem. Int. Ed. 43 (2004) 5697.