Electrical performance and structural analysis of La1−xBaxGa0.8Mg0.2O3−δ solid electrolyte

• La1−xBaxGa1−yMgyO3−δ electrolytes were synthesized by a solid-state reaction.
• La1−xBaxGa1−yMgyO3−δ (x = 0.03–0.1, y = 0.2–0.25) are the Imma structure.
• LBGM0525 specimen had a higher conductivity (≈0.1 S/cm) at 800 °C.
• The activation energy was ca. 0.83–1.27 eV at 500 °C–800 °C in the LBGM0525.
• TECs of the LBGM samples were in the range of 10 × 10−6 to 14 × 10−6/°C.

The aim of this study was to develop La1−xBaxGa1−yMgyO3−δ (x = 0.03–0.1, y = 0.2–0.25) (LBGM) electrolytes for intermediate-temperature solid-oxide fuel cells (SOFCs); these electrolytes were synthesized via a solid-state reaction. In the study, the La1−xBaxGa1−yMgyO3−δ samples crystallized in an orthorhombic (Imma) structure, and a BaLaGa3O7 phase was detected for x ≥ 0.08 at a fixed y = 0.2. The solubility limit of the Ba ions increased with an increase in the Mg content in the matrix. Two active Raman bands at ca. 677 and 739 cm−1 were observed, and they were attributed to the oxygen vacancies. The La0.95Ba0.05Ga0.75Mg0.25O3−δ sample had a higher conductivity ca. 0.1 S/cm at 800 °C, and an activation energy of ca. 0.83–1.27 eV at 500–800 °C. The thermal expansion coefficient (TEC) of the LBGM samples at 200–800 °C was in the range of 10 × 10−6 to 14 × 10−6/°C.