Synthesis and Characterization of Nano‐Hetero‐Structured Dy Doped CeO2 Solid Electrolytes Using a Combination of Spark Plasma Sintering and Conventional Sintering

Abstract

Doped ceria (CeO2) compounds are fluorite‐type oxides that show oxide ionic conductivity higher than yttria‐stabilized zirconia in oxidizing atmosphere. As a consequence of this, considerable interest has been shown in application of these materials for “low” (500°–650°C) temperature operation of solid oxide fuel cells (SOFCs). To improve the conductivity in dysprosium (Dy) doped CeO2, nano‐size round shape particles were prepared using a coprecipitation method. The dense sintered bodies with small grain sizes (<300 nm) were fabricated using a combined process of spark plasma sintering (SPS) and conventional sintering (CS). Dy‐doped CeO2 sintered body with large grains (1.1 μm) had large micro‐domains. The conductivity in the sintered body was low (−3.2 S/cm at 500°C). On the other hand, the conductivity in the specimens obtained by the combined process was considerably improved. The micro‐domain size in the grain was minimized using the present process. It is concluded that the enhancement of conductivity in dense specimens produced by the combined process (SPS+CS) is attributable to the microstructural changes within the grains.