Effect of CuO doping on sinterability, mechanical and electrical properties of Sm-doped CeO2 ceramic thick membrane solid electrolytes

Ce0.8Sm0.2O1.9·(CuO)x (CSCO, x=0, 0.5, 1.0, 2.0 and 5.0%) powders were synthesized by a polyvinyl alcohol (PVA) assisted combustion method and labeled as CSO, CSCO-0.5, CSCO-1, CSCO-2 and CSCO-5, respectively. The corresponding pellet-shaped samples were sintered at 900-1400 °C and then characterized in sinterability, mechanical and electrical properties. Addition of CuO lowers the densification sintering temperature, and enhances mechanical strength which is attributed to a fracture transformation from intergranular to transgranular, as well as enhanced density. Compared with the CSO sintered at 1400 °C, a same densification degree is achieved for the CSCO-1 sintered only at 900 °C, and a significant increase in biaxial flexural strength is obtained from 191±13 MPa to 253±19 Mpa. This slight modification in chemical composition also results in a decrease in activation energy and thus an improvement in total electrical conductivity.