6Li and 7Li nuclear magnetic resonance were used to investigate the Li ion dynamics in LiPO3 glass. In particular, 6Li nuclear magnetic resonance stimulated-echo experiments were used to provide straightforward access to two-time correlation functions characterizing the Li ionic hopping motion in the millisecond regime in a glassy ion conductor. Temperature-dependent measurements serve to separate the spin diffusion contribution and the dynamic contribution to the stimulated-echo decays. The 6Li nuclear magnetic resonance correlation functions of LiPO3 glass describing the Li ionic motion show pronounced non-exponential decays, which could be well described by a stretched exponential function with a temperature-independent small stretching parameter β = 0.27, indicating the complex nature of the Li dynamics. The temperature dependence of the mean correlation times <τ> resulting from these stimulated-echo experiments was described by an activation energy Ea = 0.66eV. The values of <τ> were in good agreement with time-constants from previous electrical and mechanical relaxation studies. At appropriate temperatures, the 6Li and 7Li nuclear magnetic resonance spectra were superpositions of a broad and a narrow spectral component, which result from slow and fast Li ions, respectively, on the nuclear magnetic resonance time scale. A detailed analysis of the temperature dependence of these line shapes provided information about the distribution of correlation times.

6Li and 7Li NMR Line-Shape and Stimulated-Echo Studies of Lithium Ionic Hopping in LiPO3 Glass. S.Faske, H.Eckert, M.Vogel: Physical Review B, 2008, 77[10], 104301 (10pp)