The 6Li and 7Li MAS nuclear magnetic resonance signals of fast ionic conductors, Li2−2xMg1+xCl4, were attributed to the two Li-ion positions of their inverse spinel-type structure. The chemical shifts of the two 6Li signals of Li2MgCl4 were 1.2 and 0.3ppm, when compared with 6LiCl. That of normal spinel-type 6Li2ZnCl4 was equal to 0.2ppm. The relative intensities of the 6Li signals reflected quite well the occupation factors of the tetrahedral and octahedral sites, but the intensities of the 7Li signals deviated strongly from the occupation factors. This was attributed to distortion of the 7Li signals by quadrupolar interaction. The various chemical shifts and half-widths of the signals were considered with respect to shielding and dipolar interaction. Their change, with increasing Mg content, could be explained by the formation of vacancies at the tetrahedral sites upon replacing Li+ by Mg2+ and by clustering of the randomly distributed Li+ and Mg2+ ions at octahedral sites.

6Li and 7Li MAS-NMR Studies on Fast Ionic Conducting Inverse Spinel-Type Li2−2xMg1+xCl4 and Normal Spinel-Type Li2ZnCl4. R.Nagel, C.Wickel, J.Senker, H.D.Lutz: Solid State Ionics, 2000, 130[1-2], 169-73