Long-range Li diffusion parameters of amorphous LiNbO3 were probed by 7Li 2-time spin-alignment echo nuclear magnetic resonance spectroscopy which was sensitive to slow Li dynamics. The jump rates which were extracted from the spin-alignment echo decay curves exhibited Arrhenius behaviour between 293 and 413K. The activation energy (0.41eV) was in good agreement with that of the high-temperature flank of the 7Li nuclear magnetic resonance spin-lattice relaxation rate peak. The latter was predicted to be about 0.4eV when taking into account the frequency dependence of the corresponding spin-lattice relaxation rates on the low-T flank. Previous measurements of the spin-lattice relaxation rate had to be restricted to temperatures below 450K in order to avoid crystallization of the material. Thus, only the low-temperature flank of the diffusion induced spin-lattice relaxation rate peak had been accessible yielding information about short-range Li diffusion.

Li Dynamics in Amorphous LiNbO3 as Probed by Solid State NMR on Different Length Scales. M.Wilkening, M.Masoud, P.Heitjans: Diffusion Fundamentals, 2008, 8, 5.1