Two separate Li+ ionic motions observed by Li-7 and B-11 NMR in xLi(2)S+(1-x)B2S3 glassy fast ionic conductors

Studies of ion dynamics in the highly conductive glassy fast ionic conductor (FIC) xLi(2)S + (1-x)B2S3 (x = 0.65 and 0.70) were made with NMR nuclear spin lattice relaxation (NSLR) R(1)(omega, T) of both mobile Li-7 and immobile B-11 ions, and Li-7 NMR line narrowing delta nu(T). The possible dependence of ion dynamics on the short range order structures (SRO) and the distribution of activation energies (DAE) in this highly conductive FIC was investigated. Two Gaussian DAE were employed to fit Li-7 NSLR data, where each Gaussian DAE was correlated to a separate B-11 NSLR in a BS3 and in a BS4 group. The long range diffusion of Li ions among BS, groups and a seemingly localized ionic hopping motion around BS4 group is suggested as a microscopic model for the ion dynamics in thioborate glasses, namely a 'two channel relaxation'.