Oxygen exchange kinetics on a highly oriented La0.5Sr0.5CoO3-delta thin film prepared by pulsed-laser deposition

Oxygen exchange at a highly oriented La0.5Sr0.5CoO3-delta thin film prepare d on (100) surfaces of an yttria-stabilized zirconia single crystal by puls ed-laser deposition was studied with ac impedance spectroscopy under variou s temperatures and oxygen partial pressures. Three distinctive features obs erved in the impedance spectra were assigned to contributions from the ioni c conduction of the electrolyte, oxide ion transfer across the electrode/el ectrolyte interface, and the oxygen exchange on the film surface. An equiva lent circuit model was proposed to analyze the impedance results, from whic h the surface chemical exchange coefficients, k(chem), were derived as a fu nction of temperature and oxygen partial pressure. (C) 2001 American Instit ute of Physics.