Thermal and mechanical properties of rare earth-doped ceria ceramics

Oxalate coprecipitation method was applied to prepare rare earth-doped ceria powders with a composition of Ceo.8R0.2O1-9 (R=Sm, La). The precipitate produced was decomposed at 600 degrees C in air to the oxide solid solution. After milling with alpha-alumina ball, the powders were densified to 98-99% calculated density at 1600 degrees C. No influence of doped rare earth element on the thermal expansion coefficient of CeO2 was measured (11.4 x 10(-6)-11.8 x 10(-6) K-1). The Ce0.8Sm0.2O1.9 formed by colloidal processing and with 86-98% relative density offered 53-81 MPa of four-point flexural strength and 9.1 of Weibull modulus. Large flaws of 200-300 mu m sizes produced near surface were fracture origins. The Young's modulus and Vicker's hardness were also measured for Ce0.8Sm0.2O1.9. These measured thermal and mechanical data were compared with those of component materials of solid oxide fuel cell. (C) 1999 Elsevier Science S.A. All rights reserved.