Local Multimodal Electro-Chemical-Structural Characterization of Solid-Electrolyte Grain Boundaries

Xin Xu*, Connor Carr, Xinqi Chen, Benjamin D. Myers, Ruiyun Huang, Weizi Yuan, Sihyuk Choi, Dezhi Yi, Charudatta Phatak, Sossina M. Haile

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Typical models of polycrystalline ionic materials treat the grain boundary properties as single valued, without consideration of the full range of values that define the macroscopically measured average. Here a unique experimental platform suitable for local multimodal characterization of individual grain boundaries in bicrystal fibers is reported. A variation of three orders of magnitude in the grain boundary conductivity of ceria is observed, as measured across six individual bicrystals by both alternating current impedance spectroscopy and direct current (D.C.) linear sweep voltammetry. Nonlinear behavior of the D.C. measurements is consistent with resistance due to a space charge effect. Time-of-flight secondary ion beam spectroscopy reveals a correlation between grain boundary resistance and the concentration of impurities Si, Al, and Ca segregated at the grain boundaries, although the bulk concentrations of these impurities are negligible. Electron backscatter diffraction analysis of the crystal orientations suggests a correlation between the misorientation across the grain boundaries and grain boundary resistance. These correlations point towards a grain boundary resistance that arises from impurity-generated space charge effects and variations in impurity concentration and hence resistivity driven by the energetics of impurity segregation to grain boundaries of differing surface energies.

Original languageEnglish (US)
Article number2003309
JournalAdvanced Energy Materials
Volume11
Issue number10
DOIs
StatePublished - Mar 11 2021

Keywords

  • ceria bicrystals
  • charge transport
  • grain boundaries
  • ionic conductivity
  • space charge effect

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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