Temperature dependence of the near constant loss in ionic conductors:: a coupling model approach

We analyse experimental ac conductivity data of various glassy (61SiO(2).35Li(2)O.3Al(2)O(3).P2O5 and alkali triborates of formulae M2O.3B(2)O(3) with M = Li, Na, K or Rb) and crystalline ionic conductors (Li0.18La0.61TiO3 and yttria stabilized zirconia with a 16% molar yttria content, (Y2O3)(0.16)(ZrO2)(0.84)) at temperatures ranging from 400 down to 8 K. At sufficiently low temperatures the dielectric loss is found to be almost independent of frequency, and this near constant loss (NCL) shows a weak temperature dependence in all cases. We find good agreement between the experimental data and the theoretical predictions of a new scheme for NCL based on the coupling model.