Thin BaCe[sub 0.8]Gd[sub 0.2]O[sub 3−δ] Protonic Electrolytes on Porous Ce[sub 0.8]Gd[sub 0.2]O[sub 1.9]–Ni Substrates

Abstract

Thin proton-conducting electrolytes with 20 μm thickness and a nominal composition Ba Ce0.8 Gd0.2 O3-δ were prepared over porous substrates composed of Ce0.8 Gd0.2 O1.9 (CGO)-Ni. The fabrication method includes the simultaneous cofiring and solid-state reaction at 1300°C of three screen-printed layers: mixed conducting anode layer, CGO, and an upper-coated BaC O3 layer. The resulting asymmetric membranes with 5×5 cm2 geometry are gastight. The solid-state reaction resulted in the formation of (i) an electrolyte with large (∼2-5 μm) grains and high packing density and (ii) anode layer comprising finely grained Ba Ce0.8 Gd0.2 O3-δ and Ni particles with a thickness around 5 μm. The layer morphology, phase distribution, and lattice composition has been investigated by X-ray diffraction, energy-dispersive spectroscopy scanning electron microscopy, and secondary-ion mass spectrometry. The preparation of the substrate by warm-pressing and tailoring of the porosity and sintering activity are also thoroughly described. DC-electrical conductivity and ac-electrochemical characterization showed that the supported Gd-doped barium cerate electrolyte produced by solid-state reaction has interesting proton-conduction properties for application in solid oxide fuel cells, hydrogen separation, and sensors. © 2007 The Electrochemical Society.