Local Ion Dynamics in Polycrystalline β-LiGaO₂: A Solid-State NMR Study

Solid-state nuclear magnetic resonance spectroscopy is an efficient technique to characterize dynamics and structure of materials. It has been widely used to elucidate ion dynamics in lithium ion conductors. Fast moving lithium ions are needed in energy storage devices, whereas slow ion motion is exploited in some materials used, for example, as blankets in fusion reactors. β-lithium gallium oxide (LiGaO₂) is a slow Li⁺ ionic conductor similar to γ-lithium aluminum oxide (LiAlO₂). In an ion conductor, in addition to the main diffusion process, localized motions (to-and-fro jumps) may be present. In the present work, with the help of solid-state NMR experiments, we report on the localized movements of Li⁺ ionic species in β-LiGaO₂ in the temperature range between 300 K and 450 K. In this work, we have mainly extracted the peculiarities of ion dynamics from ⁷Li spin-alignment echo NMR measurements and the observation of the motional narrowing of the central transition signal of ⁷Li.