Aggregation of the doping salt in B2S3-Li2S-LiI glasses, effect on the dynamical properties

LiI aggregates have been detected by Li-7 NMR in LiI-rich (1-y) [0.4B(2)S(3 ) 0.6Li(2)S] yLiI thioborate glasses. Such aggregates are not detectable by XRD because of their size. The amount of actually dissolved doping salt in the LiI-rich glasses is smaller than for glasses with lower y, for which n o aggregates exist. The formation of aggregates leads to a decrease in the ionic DC conductivity. in addition, the DC behaviour of the dissolved Lithi um ions is perturbed by the presence of the nearby aggregates, but this see ms not to be the case for the high frequency ion hops, as probed by NMR. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.