Pb ₂Ru ₂O _6.5 as a low-temperature cathode for bismuth oxide electrolytes

A chemical route, called direct condensation method (DCM), was developed to synthesize nanometric Pb ₂Ru ₂O _6.5 as a cathode material for intermediate temperature solid oxide fuel cells. The electrolyte used was (Er ₂O ₃) _0.2(Bi ₂O ₃) _0.8 (ESB). Porous lead ruthenate and ESB-lead ruthenate composite electrodes were deposited onto dense ESB pellets. X-ray diffraction, field-emission scanning electron microscopy, and energy dispersive spectroscopy analysis were used to investigate the reactivity and the morphology of the materials prepared. Electrochemical impedance spectroscopy in air at different operating temperatures was used to evaluate polarization and electrical performance of cells in symmetric configuration. Lead ruthenate-based electrodes were sintered at different temperatures to understand the role of the triple-phase boundary on the electrode polarization. An increase in the sintering temperature induced the formation of intermediate phases at the interface between ESB and the pyrochlore, thereby resulting in an increase in the polarization resistance at the electrode/electrolyte interface of the symmetric cells.