Phase stability, thermal, electrical and structural properties of (Bi₂O₃)_1−x−y(Sm₂O₃)_x(CeO₂)_y electrolytes for solid oxide fuel cells

ABSTRACT

In this study, (Bi₂O₃)_1−x−y(Sm₂O₃)_x(CeO₂)_y ternary system was synthesized by using solid-state reaction method. Structural, morphological, thermal and electrical properties of the samples were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy, thermo gravimetry/differential thermal analyzer and four-probe method. The XRD measurement results indicated that the samples (x = 10–15, y = 5–10–15–20) had cubic δ-phase crystallographic structure. The phase stability of the samples was checked by the differential thermal analyzer measurements, which indicates most of the samples have stable δ-Bi₂O₃ phase. The electrical conductivity measurement results showed that the electrical conductivity increased with mol% CeO₂ molar ratio at a fixed molar ratio of Sm₂O₃. The highest electrical conductivity obtained for the (Bi₂O₃)_0.65(Sm₂O₃)_0.15(CeO₂)_0.20 system was 1.55 × 10⁻² (Ω.cm)⁻¹ at 600 °C. The activation energies were also calculated at low temperature range (350–650 °C) which vary from 1.1325 to 1.4460 eV and at high temperature (above 650 °C) which vary from 0.4813 to 1.1071 eV.

KEYWORDS:

• Solid oxide fuel cell (SOFC)
• solid electrolyte
• solid-state reaction
• electrical conductivity
• activation energy

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Erciyes University's Research Fund, Project Number FBD-12-4109.