Lanthanide element variation in rare earth doped ceria – FeCo2O4 dual phase oxygen transport membranes
Liudmila Fischer,
Ke Ran,
Christina Schmidt,
Kerstin Neuhaus,
Stefan Baumann,
Patrick Behr,
Joachim Mayer,
Henny J.M. Bouwmeester,
Arian Nijmeijer,
Olivier Guillon,
Wilhelm A. Meulenberg
Affiliations
Liudmila Fischer
Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany; Faculty of Science and Technology, Inorganic Membranes, University of Twente, 7500 AE, Enschede, the Netherlands; Corresponding author. Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
Ke Ran
Central Facility for Electron Microscopy GFE, RWTH Aachen University, 52074, Aachen, Germany; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons ER-C, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
Christina Schmidt
Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research IEK-12, Helmholtz-Institute Münster, 48149, Münster, Germany
Kerstin Neuhaus
Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research IEK-12, Helmholtz-Institute Münster, 48149, Münster, Germany
Stefan Baumann
Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany; Corresponding author.
Patrick Behr
Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
Joachim Mayer
Central Facility for Electron Microscopy GFE, RWTH Aachen University, 52074, Aachen, Germany; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons ER-C, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
Henny J.M. Bouwmeester
Faculty of Science and Technology, Inorganic Membranes, University of Twente, 7500 AE, Enschede, the Netherlands
Arian Nijmeijer
Faculty of Science and Technology, Inorganic Membranes, University of Twente, 7500 AE, Enschede, the Netherlands
Olivier Guillon
Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany; Jülich Aachen Research Alliance: JARA-Energy, 52425, Jülich, Germany
Wilhelm A. Meulenberg
Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany; Faculty of Science and Technology, Inorganic Membranes, University of Twente, 7500 AE, Enschede, the Netherlands
The increased interest in dual-phase membrane materials for oxygen separation leads to the continuous optimization of their composition. Rare-earth doped ceria is a promising candidate as the ion-conducting phase in the membrane. Spinel-structured FeCo2O4 was investigated as an electronic conducting phase forming an additional electronic conducting perovskite-structured phase during sintering when combined with Ce1−xLnxO2−δ. The influence of rare-earth lanthanide elements, i.e., Gd and Sm, as well as their concentration, i.e. x = 0.1 and 0.2, on the final phase composition and microstructure as well as its related functional properties in particular oxygen permeation is analyzed. 20 mol.% doping of either Gd or Sm reveals a multi-phase microstructure after sintering. Moreover, segregation of Gd/Sm, iron, and cobalt is found at the ceria-ceria grain boundaries in Ce0.8Sm0.2O2−δ- and Ce0.9Gd0.1O2−δ-based composites. In contrast, 10 mol.% Gd–doping leads to a dual-phase membrane material without the formation of any other phase. In all cases, the percolation threshold is reached at approx. 20 vol% of the electron-conducting phase in the system leading to similar maximum permeation rates determined by the ionic conductivity of the ceria phase.
