The interplay and impact of strain and defect association on the conductivity of rare-earth substituted ceria

George F. Harrington, Lixin Sun, Bilge Yildiz, Kazunari Sasaki, Nicola H. Perry, Harry L. Tuller

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

The effects of strain on the ionic conductivity of rare-earth substituted CeO 2 have been extensively studied, but the results have been inconsistent and focused upon the ‘optimised’ conductors such as Gd or Sm substituted CeO 2 where defect association is minimised. By thermally annealing epitaxial films deposited by pulsed laser deposition, we varied the strain systematically, whilst avoiding any influence from interfacial or grain boundary effects. The activation energy of the in-plane conductivity was found to increase with increasing compressive biaxial strain, which was quantitatively in excellent agreement with previous computational and experimental studies. These results provide a much needed quantitative consensus on the effects of lattice strain on ionic transport. Furthermore, we demonstrate that the change in the activation energy for Yb-substituted CeO 2 is around three times that for Gd or La substitutions for the same applied strain, indicating the important role played by defect association. These results have significant implications for ionic transport at reduced or ambient temperatures, where changes in conductivity due to strain may be several orders of magnitude larger for ‘non-optimised’ conductors compared with ‘optimised’ conductors. We rationalise our results by considering the defect-defect interactions in these materials and through force-field calculations.

Original languageEnglish
Pages (from-to)447-458
Number of pages12
JournalActa Materialia
Volume166
DOIs
Publication statusPublished - Mar 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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