Composition dependence of the dispersive nature of the ac conductivity in ionic conductors Gd2Ti2-yZryO7 and Li0.5-xNaxLa0.5TiO3

J. García-Barriocanal, K. J. Moreno, A. F. Fuentes, J. Santamaría, C. León

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Abstract

We present Admittance Spectroscopy measurements on two different ionically conducting materials, Gd2Ti2-yZryO7 and Li0.5-xNaxLa0.5TiO3. Electrical relaxation data have been found to be well described by stretched exponential functions of the form Φ(t) = exp(-(t/τ)1-n). In Gd2Ti2-yZryO7 the concentration of mobile ions in the whole series is very low, from 1% to 0.02 %, and we find that by strongly decreasing the density of mobile ions the value of the exponent n shows a significant decrease from 0.44 ± 0.01 to 0.16 ± 0.01. In Li0.5-xNaxLa0.5TiO3 we have investigated changes in ion dynamics when approaching the percolation threshold for lithium diffusion by increasing the number of immoble sodium ions, and found that the exponent n increases towards a value of 0.81 ± 0.01 as the mobility of lithium ions becomes more and more constrained close to the percolation threshold. Both results are discussed in terms of the importance of ion-ion correlations in the dispersive behavior of the electrical conductivity.

Original languageEnglish (US)
Pages (from-to)5141-5146
Number of pages6
JournalJournal of Non-Crystalline Solids
Volume352
Issue number42-49 SPEC. ISS.
DOIs
StatePublished - Nov 15 2006

Keywords

  • Dielectric properties
  • Fast ion conduction
  • Relaxation, electric modulus

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