The in situ generated emerging phase inside dual phase oxygen transport membranes

Ke Ran*, Fanlin Zeng, Liudmila Fischer, Stefan Baumann, Wilhelm A. Meulenberg, Kerstin Neuhaus, Joachim Mayer

*Corresponding author for this work

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The in situ generated emerging phase inside the dual-phase oxygen transport membranes (DP-OTMs) plays a crucial role in boosting the overall performance of DP-OTMs. However, its detailed structure and properties are still not fully understood. Utilizing advanced transmission electron microscopy (TEM) techniques, the emerging phase GdxCe1-xFeyCo1-yO3-δ (GCFCO) inside the CexGd1-xO2-δ-FeCo2O4 (CGO-FC2O) OTMs was successfully characterized at the atomic scale. The newly formed GCFCO is primarily surrounded by the CGO, and contributes to a significant reduction of non-solute segregation at the CGO grain boundaries. Electronic characteristics of the GCFCO shows a sensitive dependence on its chemical composition, including the valence state of Ce and Fe as well as the oxygen vacancies. Additional CGO-GCFCO interfaces were introduced, where almost intact crystal structures were observed with slight Gd and Co segregation ∼1 nm at the edges. Approaching the interface, on the CGO side, only a minimum drop of the Ce valence was determined. On the GCFCO side, mixed Ce3+ and Ce4+ are partially occupying the Gd sites, while Fe and Co valence stay constant until the edge. Our study provides novel insight into the phase information within CGO-FC2O composites, which paves the path towards superior performance of various DP-OTMs.

Original languageEnglish
Article number118034
JournalActa materialia
Early online date19 May 2022
Publication statusPublished - 1 Aug 2022


  • EDXS
  • EELS
  • Emerging phase
  • Interface segregation
  • Oxygen transport membrane
  • Valence states
  • n/a OA procedure

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