Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 30: POSTER: Chemical physics

CPP 30.63: Poster

Tuesday, March 8, 2005, 16:30–18:30, Poster TU D

Lithium Diffusion in the 2D Fast Ion Conductor h-Li_0.7TiS₂ Probed by Nuclear Magnetic Relaxation and Two-Time ⁷Li Stimulated-Echo NMR — •Martin Wilkening, Wilfried Küchler, and Paul Heitjans — Universität Hannover, Institut für Physikalische Chemie und Elektrochemie

Classical spin-spin and spin-lattice relaxation NMR in the laboratory as well as in the rotating frame on the one hand and stimulated-echo NMR on the other hand are used for the first time for a comprehensive investigation of Li diffusion in hexagonal h-Li_0.7TiS₂. Combining these different techniques the same 2D diffusion process in layered Li_0.7TiS₂ was probed over a dynamic range of almost 10 orders of magnitude with jump rates ranging from 1 · 10⁻¹ s⁻¹ to 7.8 · 10⁸ s⁻¹ (148 – 510 K). Whereas Li jump rates in the GHz to kHz range were probed by recording diffusion induced spin-lattice relaxation rates in the laboratory and rotating frame, ultra-slow Li jumps in the kHz to sub-Hz range were detected directly by recording mixing-time dependent two-time spin-alignment echoes. Taken together, the jump rates from the different methods obey the same Arrhenius behaviour with an activation energy of 0.41(1) eV and a preexponential factor of 6.3(1) · 10¹² s⁻¹.