التفاصيل البيبلوغرافية
| العنوان: |
Long-term stability of oxygen surface exchange kinetics of Pr0.8Ca0.2FeO3-δ against SO2-poisoning. |
| المؤلفون: |
Berger, Christian1, Bucher, Edith1 edith.bucher@unileoben.ac.at, Gspan, Christian1, Menzel, Alexander1, Sitte, Werner1 |
| المصدر: |
Solid State Ionics. Nov2018, Vol. 326, p82-89. 8p. |
| مصطلحات موضوعية: |
*CHEMICAL kinetics, *SOLID oxide fuel cells, *REACTIVITY (Chemistry), *FUEL cells, *OXYGEN |
| مستخلص: |
Abstract The long-term stability of the oxygen exchange kinetics of the Sr- and Co-free solid oxide fuel cell (SOFC) and solid oxide electrolyser cell (SOEC) air electrode material Pr 0.8 Ca 0.2 FeO 3-δ (PCF82) is investigated by in-situ dc-conductivity relaxation measurements. The chemical oxygen surface exchange coefficient k chem is determined as a function of time at 700 °C under ideal (O 2 -Ar atmosphere) and accelerated ageing conditions (O 2 -Ar with 2 ppm SO 2). In pure O 2 -Ar PCF82 shows fast oxygen surface exchange kinetics with k chem = 6 × 10−4 cm s−1 and excellent stability for 1000 h. Due to the addition of 2 ppm SO 2 to the test gas only a moderate degradation occurs with k chem decreasing to 8 × 10−5 cm s−1 during further 1000 h. Post-test analyses by scanning (transmission) electron microscopy and X-ray photoelectron spectroscopy show S-rich secondary phases in the near-surface region of the SO 2 -poisoned sample. These inactive phases occur in an island-like arrangement of relatively large crystals, whereas significant amounts of the surface remain unaffected. This effect explains the high stability of the oxygen exchange kinetics of PCF82 against SO 2 -poisoning in comparison to state-of-the art materials like La 0.6 Sr 0.4 CoO 3-δ (LSC64). Highlights • Pr 0.8 Ca 0.2 FeO 3-δ (PCF82) exhibits fast oxygen exchange kinetics. • Excellent long-term stability of oxygen exchange kinetics at 700 °C • Minor degradation during 1000 h in O 2 -Ar with 2 ppm SO 2 • Post-test analyses by SEM-EDX, XPS and TEM • Degradation correlated to CaSO 4 and Pr 2 (SO 4) 3 formation. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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