Monophase samples of fast ionic conductors La2/3-xLi3xTiO3, with x varying from 0.06 to 0.13, were prepared by solid-state reaction. The total dc-conductivity was measured by complex impedance spectroscopy in the 10MHz to 1Hz frequency range. Considering only the resulting location of O atoms and employing bond valence equations, the conduction geometry and direct-current ionic conductivity were modeled. An averaged pathway for the Li+ conduction was proposed here, assuming that the time-averaged position for Li+ was the geometrical center of the A-cage. The saddle point of this pathway (Vumax) could be related to the activation energy for the ionic jump. Moreover, in order to model dc-ionic conductivity, not only activation energy, but also number of carriers and site occupancies were considered. Three possibilities for the Li+ location in the structure were proposed in order to predict bulk conductivity in the La2/3-xLi3xTiO3 phase. Experimental evidence allows the exclusion of one of the 3 possibilities, while the other 2 were both in agreement with experimental values.

Modeling Li-Ion Conductivity in Fast Ionic Conductor La2/3-xLi3xTiO3. D.Mazza, S.Ronchetti, O.Bohnké, H.Duroy, J.L.Fourquet: Solid State Ionics, 2002, 149[1-2], 81-8