Dynamics of mobile oxygen ions in disordered pyrochlore-type oxide-ion conductors

M. R. Díaz-Guillén, K. J. Moreno, J. A. Díaz-Guillén, A. F. Fuentes, J. García-Barriocanal, J. Santamaría, C. León

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Scopus citations


We investigate the effect of cation size in the dc activation energy needed for oxygen ion conductivity, Edc, in highly disordered pyrochlore-type ionic conductors A2B2O7. Twenty compositions of general formula Ln2Zr2-yTiyO7 (Ln = Y, Dy and Gd) and Gd2-yLayZr2O7, were prepared by mechanical milling and their electrical properties measured by using impedance spectroscopy at different temperatures. We also evaluate, by using Ngai's Coupling Model, the effect of cation radii RA and RB, on the microscopic potential-energy barrier, Ea, that oxygen ions encounter when jumping into neighboring vacant sites. We find that for a fixed B-site cation radius RB, both activation energies decrease with increasing A-site cation size, RA, as a consequence of the increment in the unit cell volume. In contrast, and for a given RA size, the dc activation energy Edc of the Ln2Zr2-yTiyO 7 series increases when the average RB size increases. The latter behavior is explained in terms of the enhanced interactions among mobile oxygen ions as the structural disorder increases when RB approaches RA.

Original languageEnglish (US)
Title of host publicationDiffusion in Materials - DIMAT2008
PublisherTrans Tech Publications Ltd
Number of pages8
ISBN (Print)3908451728, 9783908451723
StatePublished - 2009
Event7th International Conference on Diffusion in Materials - Lanzarote, Spain
Duration: Oct 28 2008Oct 31 2008


Other7th International Conference on Diffusion in Materials


  • Impedance spectroscopy
  • Mechanical milling
  • Oxide-ion conductors


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