⁷Li NMR and related studies in LISICON system

Abstract

⁷Li NMR studies in the polycrystalline solid electrolytes Li₁₄Zn(GeO₄)₄ and Li₁₂Zn₂(GeO₄)₄ (LISICON System) have been carried out in the temperature range 209 K to 398 K. Onset of NMR line narrowing was observed at 230 K for Li₁₄Zn(GeO₄)₄ and at 240 K for Li₁₂Zn₂(GeO₄)₄ and became appreciable with increasing temperature in both the cases. Activation energies calculated were 0.19 eV and 0.17 eV respectively. The conductivity variation with temperature was qualitatively similar to that of the NMR linewidth but the activation energies of 0.60 eV and 0.47 eV respectively obtained were much higher. Possible reasons for the difference are discussed. Conductivity, DTA, TGA and ¹H and ⁷Li NMR studies on unsealed samples show the important role played by moisture in blocking the motion of Li⁺ ions in these compounds.