Ce02-based oxides have recently been shown to have great potential as electrolytes in medium temperature solid oxide fuel cell applications, primarily due to their high ionic conductivity [1-3]. Steele et al. [4], for example, have examined a cell of the type:

02, Lao.6Sro.4Feo.8Coo.203lCeo.9Gdo.iOi.95lNi-Zr02, H2/H2O at 715*C. Gd203 doped Ce02 has been reported [5] as having one of the highest oxygen ion conductivities of the ceria-based materials. An ionic conductivity of 8.3 x 10-2 s/cm has been reported for (CeO2)0.8(GdO 1.5)0.2 at 800*C, which is approximately four times that of Y203-doped Zr02, at the same temperature [6].

Although the electrical properties of the material have been examined in detail, very little work has considered the microstructural/property relationships, particularly in relation to the mechanical properties. It is well know that Ce02-based materials are difficult to densify and attempts have been performed to examine this [7]. Preliminary studies have also been undertaken to examine the effect of sintering on the mechanical properties of the material [8]. In this paper we examine the effect of microstructure on the high temperature mechanical properties of (CeO2)0.8(GdO 1.5)0.2-

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