ON THE IONIC-CONDUCTIVITY AND PHASE-TRANSITIONS IN THE LI2SO4-LI2WO4 SYSTEM AND THEIR RELATION TO ION-TRANSPORT MECHANISM

Secco et al. have performed several measurements of ionic conductivity, which they have considered as "convincing evidence" that the "paddle-wheel" mechanism does not contribute significantly to ion conductivity in Li2SO4-based compositions. However, a comparison of their results in the high-conductivity range with those of other investigators suggests that their data are artifacts. The cause of this is that the resistance of their sulfate-rich samples is about 0.1 ohm at high temperatures. Thus, their results are reliable only for "normal," i.e., low, conductivities. It is briefly summarized why the "paddle-wheel" mechanism for ion transport is superior to a percolation-type mechanism for a few high-conducting phases. © 1991.