Effects of MgO additions on the electrical conduction behavior of a CeO2-based electrolyte prepared by SPS process

Ce 0.8 Sm 0.2 O 1.9 (SDC)-xMgO (x = 0, 5, 10, 15, and 20 mol%) composite powders were synthesized by a sol-gel method and then densified by spark plasma sintering (SPS) to investigate the effects of MgO additions on the electrical conduction behavior of CeO 2 -based ceramics. The microstructure and electrical performances of the SDC-MgO composite ceramics were characterized and measured by XRD , SEM, TEM, EDS and EIS . Results show that the second phase of MgO segregates at the grain boundaries of SDC when its content is higher than 5 mol% in the ceramics. The SPS process accelerates the formation of MgO lamellar grains with incomplete crystallization. As the MgO content rises from 0 to 20 mol%, the grain boundary and total electrical conductivities first increase and then decrease, and the SDC-5%MgO sample exhibits the highest total conductivity, i.e., 2.76 × 10 −2  S/cm at 650  ° C, which is 9.65% higher than that of pure SDC.