Influence of In content on the electrical conduction behavior of Sm- and In-co-doped proton conductor BaCe0.80-xSm0.20InxO3-δ

The influence of indium content on the electrical conduction behavior of Sm- and In-co-doped BaCe0.80-xSm0.20InxO3-δ proton conductor was investigated by impedance spectroscopy. The structural characteristics were studied by means of X-ray diffraction, Raman spectra, high resolution transmission electron microscopy, and thermogravimetric analysis. Both long and short range structural symmetry increased with In content, from orthorhombic (x = 0–0.50) to cubic structure (x = 0.60–0.80). No oxygen vacancy ordering or micro-domains were detected. The proton concentration of the hydrated samples BaCe0.80-xSm0.20InxO3-δ (x = 0–0.20) decreased with In level. The electrical conductivity of the co-doped samples decreased with In content in wet 5% H2/Ar and wet Ar atmospheres. The reasons for the decreased electrical conductivity were discussed. The variation of electrical conductivity of BaCe0.80-xSm0.20InxO3-δ with In concentration can be applicable to other RE- and In-co-doped BaCeO3 materials.

► Sm- and In-co-doped BaCe0.80-xSm0.20InxO3-δ was prepared. ► The local structural characteristics were studied with Raman spectra and HRTEM. ► Both long and short range structural symmetry increased with In content. ► The lattice volume and proton concentration decreased with In doping level. ► The electrical conductivity of BaCe0.80-xSm0.20InxO3-δ decreased with In content.