Total electrical conductivity and defect structure of ZrO2-CeO2-Y2O3-Gd2O3solid solutions

The use of a bilayer composite YSZ-CGO (yttria-stabilized zirconia-gadolini a-doped ceria) electrolyte for intermediate-temperature solid-oxide fuel ce lls (SOFCs) is still problematic, due to solid-state reaction and interdiff usion phenomena occurring between YSZ and CGO. To overcome this problem, a gradation in the microstructure between the single materials is proposed. T o optimize the composition of the interlayer with respect to conductivity, different compositions of the system CGO(x)YSZ(1-x) were prepared and chara cterized in order to study their transport properties. Conductivity was fou nd to reach a minimum for solid solutions where Zr and Ce are present in eq uimolar quantities. The latter are, however, the most appropriate candidate s to be applied as interlayers between the two single materials. Keeping th e Ce/Zr atomic ratio approximately equal to one, different solid solutions were prepared and characterized by varying the concentration of the trivale nt cations present, in order to clarify their role in the transport propert ies of the material. For one of the better conducting systems the cell perf ormance of the composite YSZ-interlayer-CGO film electrolyte is simulated a nd compared to that of the YSZ-CGO film electrolyte. (C) 2000 Elsevier Scie nce B.V. All rights reserved.