Rare earth doped ceria compounds are fluorite related oxides which 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 (below 500°C)’
temperature operation of solid oxide fuel cells (SOFCs). In this study, the nano-sized powders of
DyxCe1-xO2-x/2 (x=0.15 and 0.2) were prepared using ammonium carbonate co-precipitation method.
To design the nano-structure in aforementioned materials, the round shape particles were prepared
in nano-scale. The combined process of Spark Plasma Sintering (SPS) and Conventional Sintering
(CS) was examined for fabrication of nano-structured doped CeO2 solid electrolytes. The
nano-structural features in the (SPS+CS) specimen and CS specimen were observed using
transmission electron microscopy (TEM). This micro-analysis suggested that the micro-domain
with distorted pyrochlore structure exists in the grain of these materials. The conducting properties
in the specimens were strongly influenced by the micro-domain size. It is found that the present
combined process minimized the micro-domain size and maximized the conductivity in the
specimens. Also nano-structured Dy doped CeO2 sintered bodies in the present study had wide ionic
domain and high transport number of oxygen. This suggests that fabricated sintered bodies are
suitable for the solid electrolyte in low temperature operated SOFCs. It is concluded that a control
of micro-domain size is a key for development of high quality doped CeO2 electrolytes for fuel cell
application. It is expected that advanced solid electrolytes for clean energy production will be
produced by a design of nano-structure in rare earth doped CeO2 solid electrolyte.
