Li ion dynamics in Li_(3x)La_(2/3-x square 1/3-2x)TiO_3 studied by NMR

摘要

~7Li- nuclear magnetic resonance relaxation times,T_1 and T_(1Q),versus temperature are reported in the 150-900K temperature range on the lithium lanthanum titanates,Li_(3x)La_(2/3-x square 1/3-2x)TiO_3,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 betweenthe cages.The T_1 and T_(1Q) studies on ~6Li nuclei confirm the above results and show that the relaxation is not due to quadrupolar interaction at a variance,which is generally accepted.