Temperature dependence of the ionic conductivity in Li3xLa2/3-xTiO3:: Arrhenius versus non-Arrhenius

We report on the temperature dependence of the ionic conductivity at low temperatures in the crystalline lithium ionic conductor Li0.18La0.61TiO3. Time domain measurements of the electric modulus have been performed to investigate ion dynamics in the frequency range 10(-5)-10(2) Hz and for conductivity values in the range 10(-14)-10(-8) S/cm. Ionic conductivity shows an Arrhenius temperature dependence below 300 K and down to 120 K, in contrast to the non-Arrhenius behavior found at higher temperatures, demonstrating that the temperature dependence of ionic conductivity in Li0.18La0.61TiO3 cannot be described by a Vogel-Fulcher-Tamman law. (C) 2003 American Institute of Physics.