We report on the C-60, Na, and Li dynamics in NaxLi6xC60 fullerides (x = 0, 1, 5, and 6) in the temperature range 80550 K by using C-13, Na-23, and Li-7 solid state NMR. The results show that the C-60 reorientation dynamics is hindered at room temperature for the Li-enriched fullerides, but it is active for the Na rich ones with a rate of the order of few kilohertz. Na-23 and Li-7 NMR measurements show the presence of two dominant thermally activated dynamics that can be associated with Li/Na ionic motions within the octahedral sites (intrasite motion) and between the octahedral and tetrahedral sites (intersite motion). The substitution of one Na or one Li ion in the end members Li6C60 and Na6C60, respectively, yields to an increase of the hopping rate of the intersite motion, which is necessary for the ionic diffusion in possible fulleride-based ionic conductors
Molecular and Ionic Dynamics in NaxLi6–xC60
SARZI AMADE', NICOLA;MAIDICH, LUCA;CARRETTA, PIETRO;SANNA, SAMUELE
2017-01-01
Abstract
We report on the C-60, Na, and Li dynamics in NaxLi6xC60 fullerides (x = 0, 1, 5, and 6) in the temperature range 80550 K by using C-13, Na-23, and Li-7 solid state NMR. The results show that the C-60 reorientation dynamics is hindered at room temperature for the Li-enriched fullerides, but it is active for the Na rich ones with a rate of the order of few kilohertz. Na-23 and Li-7 NMR measurements show the presence of two dominant thermally activated dynamics that can be associated with Li/Na ionic motions within the octahedral sites (intrasite motion) and between the octahedral and tetrahedral sites (intersite motion). The substitution of one Na or one Li ion in the end members Li6C60 and Na6C60, respectively, yields to an increase of the hopping rate of the intersite motion, which is necessary for the ionic diffusion in possible fulleride-based ionic conductorsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
