Co-doping as a strategy for tailoring the electrolyte properties of BaCe0.9Y0.1O3–δ

Abstract The properties of single-doped BaCe 0.9 Y 0.1 O 3–δ and materials co-doped with 5 mol % of different cations (In 3+ , Zr 4+ and Nb 5+ ) with the general formula BaCe 0.85 Y 0.1 M 0.05 O 3–δ were compared to examine the influence of dopants on the electrolyte properties. The samples were synthesized by the citric-nitric autocombustion method. BaCe 0.85 Y 0.1 In 0.05 O 3–δ was successfully sintered at 1400 °C for 5 h in air, while a complete sintering of the other materials was carried out at 1550 °C. This makes the doping with In a preferable method since sintering temperatures below 1500 °C can limit BaO evaporation. The total conductivities (σ) calculated from the electrical measurements at 700 °C in wet hydrogen decreased in the following order: BaCe 0.9 Y 0.1 O 3–δ  > BaCe 0.85 Y 0.1 Zr 0.05 O 3–δ  > BaCe 0.85 Y 0.1 Nb 0.05 O 3–δ  > BaCe 0.85 Y 0.1 In 0.05 O 3–δ . The stability of the ceramics exposed to a 100% CO 2 atmosphere at 700 °C for 5 h was examined by X-ray analysis. It was observed that only BaCe 0.85 Y 0.1 In 0.05 O 3–δ could sustain the aggressive environment containing traces of secondary phases, while the other samples were partially or significantly decomposed. By taking into account the values of the Goldschmidt tolerance factor ( t ) and dopant electronegativity ( χ ), it was found that the dopant electronegativity had a decisive role in inhibiting the carbonation of the ceramics.