Processing and characterisation of fine crystalline ceria gadolinia - yttria stabilized zirconia powders

摘要

For low temperature SOFCs the yttria stabilized zirconia (YSZ) - coated ceria is a promising candidate for replacing YSZ-electrolyte. An important requirement for the co-firing feasibility of such a configuration is the densification of ceria at low temperatures (<1400 deg C). Fine crystalline gadolinia doped ceria (CGO)-powder readily sinterable at 1250 deg C was synthesized by co-precipitation with oxalic acid of 0.05 M and crystallization in methanol at 200 deg C for 6h. The fabrication and charcterisation of solid solution phases with a graded composition (CGO)_x(YSZ)_(1-x), to be used as an interlayer between YSZ and CGO, in order to avoid delamination, were also studied and discussed. CGO_xYSZ_(1-x) powders, prepared by the glycine combustion method, required higher sintering temperatures (1500 deg C) to densify, while they showed significantly lower ionic conductivity than YSZ and CGO, attributed to the large lattice deformation and scattering of oxygen ions.