Comprehensive Analysis of Ce1−xSmxO2−δ Solid Electrolytes: Structural, Microstructural, and Electrochemical Characterization for Intermediate Temperature Solid Oxide Fuel Cells

Abstract

Samarium substituted ceria has been studied as a potential electrolyte material for intermediate temperature range solid oxide fuel cells. The structural, microstructural, morphological and electrochemical properties of the Ce1−xSmxO2−δ solid electrolytes were analyzed, with different substitutions from 0.05 to 0.50. The difference in the ionic radii of Sm3+ and Ce4+ resulted in lattice strain and expansion, which was found to decrease the average size of crystallites. The ionic conductivity of ceria increases as Sm3+ concentration is increased upto a limit of 20%. This is due to the combination of vacancy-vacancy repulsion and vacancy trapping by the substitution at a higher level. However, the conductivity of Ce0.80Sm0.20O2−δ was the highest, at 4.04 × 10−2 S cm−1 at 600 °C. The grain activation energy and grain boundary activation energy were also found to be ∼0.87 eV and ∼0.74 eV respectively. The low values of activation energies indicate that Ce0.80Sm0.20O2−δ could be a suitable electrolyte material for intermediate-temperature solid oxide fuel cells.