Silver ion dynamics in silver borate glasses: spectra and multiple-time correlation functions from 109Ag-NMR

NMR Multi-Time Correlation Functions of Ion Dynamics in Solids

“…At sufficiently high temperatures, all silver ions perform fast jumps on the time scale of the inverse spectral width, τ ≈ 10 μs, leading to an averaging over diverse silver ionic environments and, thus, resonance frequencies. Consistent with the present results, 109 Ag NMR Gaussian spectra were reported for silver iodide doped silver borate glasses at low temperatures [27,33].…”

“…At intermediate temperatures, the 109 Ag NMR line shapes of glassy silver ion conductors were well described by a weighted superposition of a broad Gaussian and a narrow Lorentzian, indicating that slow (τ 10 μs) and fast (τ 10 μs) silver ions coexist [20,22,27]. In this range, cooling resulted in a continuous decrease of the relative intensity of the Lorentzian, as can be seen for the example of AgI 0.3 -(AgPO 3 ) 0.7 glass in Fig.…”

“…In detail, (i) ions that occupy the same or periodic sites at the beginning and at the end of the mixing time do contribute since, within experimental resolution, the frequencies are identical at equivalent sites, (ii) ions that reside at different sites, on average, do not contribute, and (iii) rearrangements of neighboring ions have no effect, i.e., single-particle correlations functions are measured. In 109 Ag NMR work on glassy and crystalline silver ion conductors, Δω i typically exceeds Δω d by about 3 orders of magnitude so that the above condition can be met [20][21][22][23][24][25][26][27]. Specifically, all 109 Ag NMR MT-CF of the present contribution were measured using an evolution time t p = 100μs.…”

“…Hence, NMR line-shape analysis revealed that strong dynamical heterogeneities govern ionic hopping motions in glasses. Then, it is not possible to extract reliable correlation times from a simple analysis of the temperature-dependent NMR line width, but it is necessary to take into account the existence of a broad distribution of jump rates [1,18,27]. Specifically, in recent work [18], comparison with results from mechanical and electrical relaxation measurements showed that a simple line-width analysis underestimates the correlation times and their activation energy, see Fig.…”

Atomic-scale measurement of ultraslow Li motions in glassyLiAlSi2O6by two-timeL6Wilkening1, Kuhn2, Heitjans3 2008Phys. Rev. B584520View full textAdd to dashboardCite

“…Such an effect was also found by previous 7 Li SAE NMR experiments, see Fig. 14 70 The observed t p independence of the decay rate does not indicate the influence of ͑strictly͒ localized motions on the echo decay. Presumably, the changes of the quadrupole frequencies associated with such jump processes are too small in order to be resolved even though the preparation time is chosen to be relatively long, see also Ref.…”