Dynamics of lithium ions in spinel-type 7Li2MnCl4

6Li and 7Li MAS NMR Studies on Fast Ionic Conducting Spinel-Type Li2MgCl4, Li2–xCuxMgCl4, Li2–xNaxMgCl4, and Li2ZnCl4

“…The spin-lattice relaxation time of the octahedral coordinated lithium ions ¹ is much larger than ¹ (see also below). This means that the motion of the octahedral coordinated lithium ions of Li MgCl is much slower than that of the tetrahedral coordinated ones as already established by conductivity (3, 5) and quasielastic neutron scattering experiments (26). The activation energies obtained from the 1D-EXSY experiments on the low-"eld signal of Li MgCl (6.9 and 6.6 kJ mol\) also di!er from the activation energy of 23 kJ mol\ (26) derived via quasielastic neutron scattering experiments.…”

“…600 K (21, 23) is due to long-range hopping of Li> ions disordered between the tetrahedral 8a sites and octahedral 16c interstitial sites (5), the higher G* below 600 K includes the free energy necessary for the formation of the respective Frenkel defects, i.e., 16c interstitial Li> ions. The energy barrier G*" 23 kJ mol\ is due to the relatively rapid local motions of the Li ions between the tetrahedral 8a and the octahedral interstitial 16c sites (26,27). Finally, there are very rapid hopping motions of the lithium ions between 32e split sites inside the tetrahedral voids of cubic close packing of the Cl\ ions with E "6.6}6.9 kJ mol\.…”