التفاصيل البيبلوغرافية
| العنوان: |
Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3 − δ and La2NiO4 + δ against combined chromium and silicon poisoning. |
| المؤلفون: |
Schrödl, Nina1, Bucher, Edith1 edith.bucher@unileoben.ac.at, Egger, Andreas1, Kreiml, Patrice2, Teichert, Christian2, Höschen, Till3, Sitte, Werner1 |
| المصدر: |
Solid State Ionics. Aug2015, Vol. 276, p62-71. 10p. |
| مصطلحات موضوعية: |
*SILICON compounds, *X-ray photoelectron spectroscopy, *SCANNING electron microscopy, *ELECTRIC conductivity, *DIRECT currents |
| مستخلص: |
Long-term degradation effects of combined Cr- and Si-poisoning for the promising intermediate temperature solid oxide fuel cell (IT-SOFC) cathode materials La 0.6 Sr 0.4 CoO 3 − δ (LSC) and La 2 NiO 4 + δ (LNO) were investigated at 700 °C in dry and humid atmospheres for subsequent periods of 1000 h by using dc-conductivity relaxation measurements. Changes in the chemical composition and morphology of the contaminated sample surfaces were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy and wavelength dispersive X-ray analysis and by atomic force microscopy (AFM). Upon exposure to dry and humid gas flows containing Cr- and Si-species both materials exhibit a strong decrease of the chemical surface exchange coefficient of oxygen by a factor of 110 and 40 for La 0.6 Sr 0.4 CoO 3 − δ and La 2 NiO 4 + δ , respectively, which can be attributed to the formation of Cr-containing crystallites on the degraded sample surfaces. AFM-measurements reveal faceted crystallites of lateral extensions of up to 2 μm and heights of up to 500 nm on the surface of La 0.6 Sr 0.4 CoO 3 − δ . XPS-analyses confirm the presence of high levels of Cr and Sr in these crystals, indicating the decomposition of the perovskite phase through SrCrO 4 -formation. The significantly smaller crystallites that are found on the surface of La 2 NiO 4 + δ also contain Cr, as well as elevated levels of La. For both compounds, silicon is found to spread in small patches across the entire sample surface, as determined by EDXS elemental mapping analysis. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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