To improve the understanding of Li-dynamics in oxide glasses, i.e. the effect of [AlO₄]⁻ tetrahedra and non-bridging oxygens on the potential landscape, electrical conductivity of seven fully polymerized and partly depolymerized lithium aluminosilicate glasses was investigated using impedance spectroscopy (IS). Lithium is the only mobile particle in these materials. Data derived from IS, i.e. activation energies, pre-exponential factors and diffusivities for lithium, are interpreted in light of Raman spectroscopic analyses of local structures in order to identify building units, which are crucial for lithium dynamics and migration. In polymerized glasses (compositional join LiAlSiO₄–LiAlSi₄O₁₀) the direct current (DC) electrical conductivity continuously increases with increasing lithium content while lithium diffusivity is not affected by the Al/Si ratio in the glasses. Hence, the increase in electrical conductivity can be solely assigned to lithium concentration in the glasses. An excess of Li with respect to Al, i.e. the introduction of non-bridging oxygen into the network, causes a decrease in lithium mobility in the glasses. Activation energies in polymerized glasses (66 to 70 kJ mol⁻¹) are significantly lower than those in depolymerized networks (76 to 78 kJ mol⁻¹) while pre-exponential factors are nearly constant across all compositions. Comparison of the data with results for lithium silicates from the literature indicates a minimum in lithium diffusivity for glasses containing both aluminium tetrahedra and non-bridging oxygens. The findings allow a prediction of DC conductivity for a large variety of lithium aluminosilicate glass compositions.

In order to improve our understanding of the Li-mobility in oxide glass networks with Li as the principle mobile particle, electrical conductivity and self-diffusivity of lithium was studied in two phosphate (0.2 Li2O·0.8 P2O5, 0.3 Li2O·0.2 MgO·0.5 P2O5) and one borate (0.25 Li2O·0.75 B2O3) glass compositions. Conductivity measurements provided information about ion dynamics while isotope-exchange experiments involving isotopically enriched Li diffusion glass couples provided information about long-range diffusivity of Li-isotopes through borate and phosphate networks. Due to the limitations of individual glass stabilities, the temperature range for selected experiments was very small, e.g. as in the case of Li–phosphate composition between 373 and 520 K. The activation energy for Li-migration derived from conductivity measurements was similar for Li–Mg–phosphate and Li–borate, 90.4 and 85.2 kJ/mol, while for pure Li–phosphate the value was 74.7 kJ/mol. In the case of self-diffusion, the activation energies were comparable with Li–Mg–phosphate having the highest value of 76.9 kJ/mol while Li–phosphate and Li–borate had almost the same value of 72.9 and 72.2 kJ/mol, respectively. In these glass compositions with similar Li-cation concentration, the differences in the mobility predominantly depend on structural arrangement of building units and the spatial distribution of negative potentials, as reflected in the value of HR/f, i.e. the Haven ratio divided by the correlation factor, as a mean to better understand the diffusion mechanism in glass structures, where vacancy vs. interstitial diffusion cannot be clearly defined. For Li–phosphate almost unconstrained Li-migration was indicated with the HR/f value of 0.98, while Li–Mg–phosphate had the most structural constraint on mobilized Li-cations, with the HR/f value of 0.30. Findings are compared with silicate (Li2O·3 SiO2) and aluminosilicate (Li2O·Al2O3·4 SiO2) glasses from our previous studies in order to elaborate the effect of network topology.

Li x Na2−x Ti₆O₁₃has received attention as 3d-metal oxide based anode material for possible battery application. Generally, titanium oxides represent excellent Li hosts due to their zero-strain behavior, cycling stability and high operating voltage. New developments choose Na as charge carrier, but less effort is put in the investigation of mixed cation conductors. Owing to the synthesis route of Li x Na2−x Ti₆O₁₃(0 ≤ x ≤ 2) the coordination of Na and Li in the channels is different which had been investigated by means of X-ray and neutron diffraction. Up to now, no Raman spectroscopy has been applied. This oxide is highly Raman-active, thus the local structure can also be analyzed in terms of vibrational spectroscopy. Micro-Raman spectroscopy carried out at room temperature with different cation contents (x = 0, 0.33, 1, 2) shows the continuous change from Na to Li by a superposition of the modes for Na₂Ti₆O₁₃ and Li₂Ti₆O₁₃. The only exceptions are two distinct modes. They appear either for Li (118 cm –1) or Na (135 cm –1). The results confirm the high-temperature phase stability of Na₂Ti₆O₁₃ as well as the anisotropic thermal expansion of the unit cell seen by in situ X-ray powder diffraction under two different gas atmospheres. Combining these results, we suppose that the anisotropic thermal expansion of the lattice parameters is affected by the normal vectors of the corresponding bond vibrations in Na₂Ti₆O₁₃ and Li₂Ti₆O₁₃. Crystalline-orbital calculations of the Raman shifts of Li x Na2−x Ti₆O₁₃were carried out for the cation contents x = 0, 1, 2 and Raman modes were assigned to specific bond vibrations supported by theory. Besides, this gives additionally information about the Li/Na ratio in a new and simple way.