Direct-current-induced transformation at the interface between platinum anode and holmium-doped ceria electrolyte

Under the influence of a direct current (dc), phase transformation could take place at the interface between platinum anode and holmium-doped ceria (HDC) electrolyte attemperature >= 600 degrees C. This transformation is insensitive to the doping concentration and the sintering temperature, but strongly depends on the testing temperature. As a result of the dc-induced transformation, products with a size up to hundreds of microns were separated from the anode-side surface and, correspondingly, circular holes with diameters varied from tens to hundreds of microns remained on the surface. Compared with original HDC samples, a high degree of local ordering of oxygen vacancies was found in most of the products. Based on structural and compositional studies, it is suggested that the dc-induced transformation could be attributed to the electrochemical reaction at the anode/electrolyte interface and the mobility of Ho cations promoted by the current. c 2009 American Institute of Physics. [DOI: 10.1063/1.3142263]