Effects of Sm and Gd co-doping on ionic conductivity of ceria-based electrolyte materials

This study explores the impact of co-doping on ceria-based electrolyte materials with samarium (Sm) and gadolinium (Gd) to improve their structural, morphological, and ionic conductivity properties synthesized through a co-precipitation technique using sodium hydro-oxide (NaOH) as the precipitating agent for solid oxide fuel cell (SOFC) applications. The aforementioned approach provides benefits like uniformity, high purity, and simplicity of synthesis. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the crystal structure and morphology of the synthesized materials. No secondary phases were observed revealing the phase purity of the material. A decrease in lattice constant was detected due to the replacement of a small concentration of Gd with Sm having small ionic radii compared to Sm. Homogeneity and decrease in particle size of prepared samples were observed via SEM analysis predicting the enhancement in the grain size with the reduction in grain boundaries and elemental composition through EDX agreed with the starting composition. Impedance spectroscopy was employed to measure the ionic conductivity of the electrolyte samples. Our results demonstrate a significant decrease in grain and grain boundary resistances causing the increase in ionic conductivity with the introduction of Gd and Sm as co-dopants into the ceria structure. The optimal doping concentration was found to be 10 % Gd and 10 % Sm. The co-doped ceria had a high ionic conductivity of 6.28 x 10(- 2) S/cm at 750 omicron C and a low activation energy of 0.44 eV, indicating improved ionic mobility. This study provides valuable insights into the role of Gd and Sm co-doping in enhancing the ionic conductivity of ceriabased electrolyte materials, which is crucial for the advancement of high-performance SOFCs.