Structural, thermomechanical and electrical properties of new (1 − x)Ce0.8Nd0.2O2−δ–xBaCe0.8Nd0.2O3−δ composites

• The total conductivity of (1 − x)Ce0.8Nd0.2O2−δ–xBaCe0.8Nd0.2O3−δ composites in wet air is lower than that of the basic oxides.
• Their conductivity degradation is not more than 15% for 200 h of redox-cycles at 900 °C.
• Their stability in CO2- and H2O-containing atmospheres may render them as potential candidates for IT-SOFCs.

In this work composite (1–x)Ce0.8Nd0.2O2–δ–xBaCe0.8Nd0.2O3–δ ceramics were prepared via the one-step citrate-nitrate combustion procedure, and characterised by TG-DSC, XRD analysis, and SEM. Their transport properties were investigated across various temperatures (600–900 °C) and oxygen partial pressures (10−23–0.21 atm).The XRD data reveals an occurrence of single-phase oxides at x = 0, 1 and two phases with perovskite and fluorite structure at x = 0.25, 0.5, 0.75 in powders calcined at 1100 °C. Dense ceramic samples (93–95%) were sintered in air at 1500 °C for 3 h. The concentration dependence of the mean grain size is characterized by local minimum at x = 0.5, while that of total conductivity exhibited a similar behavior; its minimal value was registered in the sample with the most extended specific grain surface. It was found that the electronic contribution to the total conductivity of the composites is reduced as compared to that of the basic Ce0.8Nd0.2O2–δ and BaCe0.8Nd0.2O3–δ materials. This leads to a better stability in the long-term redox-cycles in comparison with the basic oxides.Additionally, the conductivity in Ce0.8Nd0.2O2–δ decreases by 85%, whereas the conductivity of BaCe0.8Nd0.2O3–δ decreases by 30% after 2 redox-cycles for 200 h at 900 °C. The resulting conductivity degradation of the (1–x)Ce0.8Nd0.2O2–δ–xBaCe0.8Nd0.2O3–δ composite is no more than 15%.

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