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 °C) was obtained, and the activation energy for diffusion in gadolinia-doped ceria (GDC) was calculated as ~0.56 eV, implying that the majority of oxide ion vacancies diffuse on the surface rather than inside the bulk of the electrolyte.

Print publication: Issue 44 (4 November 2009)
Received 16 April 2009, in final form 13 July 2009
Published 7 October 2009