Characterization of samarium-doped ceria powders prepared by hydrothermal synthesis for use in solid state oxide fuel cells

In this study, Ce1−xSmxO2−δ (x = 0.0, 0.1, 0.2, 0.3, 1.0) were synthesized for use in solid oxide fuel cells (SOFCs) using an environment-friendly method of coprecipitation followed by hydrothermal treatment. XRD and TGA results revealed that the gels after coprecipitation appeared to comprise a cubic CeO2 phase with some water or hydroxyl groups attached and a Sm(OH)3 precipitate. After subsequent hydrothermal treatment, the samples with CeO2 and Sm(OH)3 precipitates were observed to be converted into a single-phase fluorite structured Ce1−xSmxO2−δ, as confirmed by Raman spectra, whereas the sample with pure Sm(OH)3 precipitates remained unchanged after treatment. FESEM and HRTEM images showed that the synthesized Ce1−xSmxO2−δ nanopowders appeared to be spherical-like particles with a single-crystal structure and a uniform particle size of 10–30 nm. The samarium dopant, when increased to 30 mol% in the Ce1−xSmxO2−δ, seemed to trigger the formation of a few nanowires with a length of ≈400 nm. The sintered Ce0.8Sm0.2O2−δ ceramics registered an electrical conductivity of 0.048 S/cm at 700 °C and an activation energy of 0.73 eV, similar or superior to those reported in the literature. The feasibility of using the Ce1−xSmxO2−δ nanopowders prepared by coprecipitation-hydrothermal method in SOFCs was confirmed.