Three-dimensional structures and lithium-ion conduction pathways of (Li2S)(x)(GeS2)(100) (- x) superionic glasses

摘要

The conduction pathways of Li ions in ((Li2S)-Li-7)(x)(GeS2)(100 - x) glasses (x = 40, 50, and 60) were predicted and visualized by combining reverse Monte Carlo (RMC) modeling and the bond valence sum (BVS) approach, using synchrotron X-ray and time-of-flight neutron diffraction data. The conduction pathways of the Li ions could be classified into four grades, according to the magnitude of vertical bar Delta V(Li)vertical bar:(I)vertical bar Delta V(Li)vertical bar <0.04 (i.e., relatively stable regions for the Li ions), (II) 0.04 <=vertical bar Delta V(Li)vertical bar <0.07, (III) 0.07 <=vertical bar Delta V(Li)vertical bar <0.10, and (IV) 0.10 <=vertical bar Delta V(Li)vertical bar <0.13; here, vertical bar Delta V(Li)vertical bar is the mismatch of the BVS for Li ions, V(Li). These were used to obtain a clear understanding of the movement of the Li ions in the ((Li2S)-Li-7)(x)(GeS2)(100 - x) glasses. It was also found that there is a definite relationship between the topology of the conduction pathways of the Li ions and the activation energy, E-a, of the electrical conduction. (C) 2015 Elsevier B.V. All rights reserved.