Enhanced ionic conductivity in La3+ and Sr2+ co-doped ceria: carbonate nanocomposite

Abstract

A series of ceria-based nanocomposites consisting of Ce0.85La0.125Sr0.025O1.9125 (LSCO) and binary carbonate mixture Li2CO3–Na2CO3 (LNCO) have been prepared as functional electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs). These have been characterized using powder X-ray diffraction, scanning electron microscope, differential thermal analysis, and measurement of conductivity as a function of temperature using complex plane impedance analysis. Crystalline ceria-based single phase formation has been found in all the composites. Carbonates are present as an amorphous phase in the composites. Impedance analysis has been used to study the electrical behavior of the composites. A jump in the conductivity vs temperature plots has been observed in all the composites containing different carbonate contents. This is related to superionic transition at the interfaces. Conductivity of the composites increases with increasing amount of carbonate. This is due to the increase in the interfacial area between the two phases, which promotes interfacial interaction between them. Composition, LSCO/35LNCO, shows conductivity of 0.203 S cm−1 at 500 °C with an activation energy of conduction of 0.19 eV. © 2015, Springer-Verlag Berlin Heidelberg.