Li ion dynamics in Li3xLa2/3-x□1/3-2xTiO3 studied by NMR

Li-7 nuclear magnetic resonance relaxation times, T-1 and T-1Q, versus temperature are reported in the 150-900 K temperature range on the lithium lanthanum titanates, Li(3x)La(2/3-x)square 1/3-2xTiO3, which are fast ionic conductors. Two characteristic frequencies of Li+ motions are evidenced in these compounds: the first is in the range of the Larmor frequency when the second one is in the range of the radio-frequency field. These frequencies are respectively attributed to motion of the Li+ ion inside the cage formed by the oxygen ions and to jumps between the cages. The T-1 and T-1Q studies on Li-6 nuclei confirm the above results and show that the relaxation is not due to quadrupolar interaction at a variance, which is generally accepted. (C) 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.