title: Reduction and oxidation of oxide ion conductors with conductive atomic force microscopy.
abstract: Local accumulation and dissipation of charges on the surface of oxide ion conductors resulting from electric potentials were observed with conductive atomic force microscopy (AFM). After a negative bias was applied at the tip, a sequence of surface potential maps appeared compatible with electron injection onto the electrolyte surface. Applying a positive bias, in contrast, generated a positive surface charge adjacent to the tip contact area. This observation is consistent with the formation of oxide ion vacancies on the oxide surface. In addition, oxide ion conductivity at a low temperature range (100-200 degrees C) was obtained, and the activation energy for diffusion in gadolinia-doped ceria (GDC) was calculated as approximately 0.56 eV, implying that the majority of oxide ion vacancies diffuse on the surface rather than inside the bulk of the electrolyte.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA. leewy@stanford.edu
authors.forename: Wonyoung
authors.initials: W
authors.lastname: Lee
authors.forename: Minhwan
authors.initials: M
authors.lastname: Lee
authors.forename: Young-Beom
authors.initials: YB
authors.lastname: Kim
authors.forename: Fritz B
authors.initials: FB
authors.lastname: Prinz