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@INPROCEEDINGS{Neuhaus:902670,
      author       = {Neuhaus, Kerstin and Schmidt, Christina and Fischer,
                      Liudmila and Ran, Ke and Mayer, Joachim and Baumann, Stefan},
      title        = {{M}easuring {D}iffusion {C}oefficients of the {C}eria
                      {P}hase in a {D}ual-{P}hase {O}xygen {P}ermeation {M}embrane
                      {U}sing a {C}ombined {P}olarization - {K}elvin {P}robe
                      {F}orce {M}icroscopy {M}ethod},
      reportid     = {FZJ-2021-04457},
      year         = {2021},
      abstract     = {Dual-phase membranes with FeCo2O4 or its iron-rich pendant
                      Fe2CoO4 and Gd-doped ceria as an oxygen ion conductor have
                      already been successfully applied as oxygen permeation
                      membranes with high permeability in the temperature range
                      above 800 °C [1-3]. Apart from Gd-doped ceria, Sm-doped
                      ceria also can be an interesting alternative in this kind of
                      composite due to its high ionic conductivity [4].As
                      especially ceria or ceria-based composites have gained more
                      and more interest for low-temperature applications, e.g. as
                      catalyst materials, current research efforts are aiming to
                      improve the composition and microstructure of such
                      dual-phase membranes for application in a membrane reactor
                      at considerably lower temperatures (below 600 °C) to
                      perform partial oxidation reactions. For temperatures
                      between 600-1200 °C the defect chemistry of these materials
                      is well established, but experimental data for low
                      temperature charge transport are limited and not fully
                      understood, yet.Kelvin Probe Force Microscopy (KPFM) is an
                      Atomic Force Microscopy (AFM)-based measurement method which
                      can measure the local surface potential (or from the physics
                      view: the Volta potential) of the sample [5, 6]. The surface
                      potential is a measure for local changes of the defect
                      chemistry, as it is directly related to the local Fermi
                      niveau [7]. The implications of local oxidation and
                      reduction at low temperatures for charge carrier mobility in
                      pure ceria, and especially in dual-phase materials, are not
                      very well understood so far, but KPFM can be used to measure
                      the surface potential difference directly at the polarized
                      contact area as well as to map the time-dependent relaxation
                      process of the introduced gradient, also giving information
                      about the local surface potential distribution, lateral
                      extent of the gradient, variations of the shape of the
                      gradient etc. [8, 9].In the present study, single ceria
                      grains in a dual-phase Ce0.8Sm0.2O2-δ + FeCo2O4 oxygen
                      permeation membrane were polarized at room temperature in
                      ambient air using a Pt-coated AFM tip and a large silver
                      paste back contact. Subsequently, the introduced defect
                      concentration gradient (which is visible as a gradient of
                      the surface potential) and the relaxation process over time
                      was monitored by KPFM.By comparing the measurement results
                      to previously acquired data of single phase ceria samples
                      with different doping concentrations and crystallinity, we
                      were able to show that by this technique, chemical diffusion
                      coefficients of a single phase in a composite material are
                      accessible.Acknowledgements:The work was funded by the
                      German Research Foundation - project #387282673.Literature:
                      1 Ramasamy, M.; Baumann, S.; Palisaitis, J.;
                      Schulze‐Küppers, F.; Balaguer, M.; Kim, D.; Meulenberg,
                      W. A.; Mayer, J.; Bhave, R.; Guillon, O. J Amer Ceram Soc
                      2016, 99 (1), 349-355. 2 Ramasamy, M.; Persoon, E. S.;
                      Baumann, S.; Schroeder, M.; Schulze-Küppers, F.; Görtz,
                      D.; Bhave, R.; Bram, M.; Meulenberg, W. A. Journal of
                      membrane science 2017, 544, 278-286. 3 Lin, Y.; Fang, S.;
                      Su, D.; Brinkman, K. S.; Chen, F. Nature Comm 2015, 6 (1),
                      1-9. 4 Mori, T.; Drennan, J.; Lee, J.-H.; Li, J.-G.;
                      Ikegami, T. Solid State Ionics 2002, 154-155, 461-466. 5
                      Örnek, C.; Leygraf, C.; Pan, J. Corr Eng Sci Tech 2019, 54
                      (3), 185-198. 6 Melitz, W.; Shen, J.; Kummel, A. C.; Lee, S.
                      Surf Sci Rep 2011, 66 (1), 1-27. 7 Zhang, Z.; Yates, J. T.
                      Chem Rev 2012, 112 (10), 5520-5551. 8 Neuhaus, K.;
                      Schulze-Küppers, F.; Baumann, S.; Ulbrich, G.; Lerch, M.;
                      Wiemhöfer, H.-D. Solid State Ionics 2016, 288, 325-330.
                      Lee, W.; Lee, M.; Kim, Y.-B.; Prinz, F. B. Nanotechnology
                      2009, 20 (44), 445706.},
      month         = {Oct},
      date          = {2021-10-10},
      organization  = {240th ECS Meeting, virtual (USA), 10
                       Oct 2021 - 14 Oct 2021},
      cin          = {IEK-12 / IEK-1 / ER-C-2},
      cid          = {I:(DE-Juel1)IEK-12-20141217 / I:(DE-Juel1)IEK-1-20101013 /
                      I:(DE-Juel1)ER-C-2-20170209},
      pnm          = {1221 - Fundamentals and Materials (POF4-122) / DFG project
                      387282673 - Die Rolle von Grenzflächen in mehrphasigen
                      Ceroxid-basierten Membranen für den Einsatz in
                      Membranreaktoren (387282673)},
      pid          = {G:(DE-HGF)POF4-1221 / G:(GEPRIS)387282673},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.1149/MA2021-02541853mtgabs},
      url          = {https://juser.fz-juelich.de/record/902670},
}