Stability of SrFeO3 based materials in the presence of SiOx species in humid atmosphere at high temperatures and pressures

Kaus, Ingeborg; Wiik, Kjell; Dahle, Marit; Brustad, Morten; Aasland, S.

doi:10.1016/j.jeurceramsoc.2007.03.040

Cited by 10 publications

(8 citation statements)

References 12 publications

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“…On this latter point Sr appears to play an important role, since it is used as a substituent in many cathode materials and has often been observed in reaction phases like Sr-silicates [11,17,18] and SrCrO 4 [2,19]. Judging from thermodynamic stabilities calcium and barium are expected to have a similar tendency to chromate formation [20].…”

Section: Introductionmentioning

confidence: 99%

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

et al. 2015

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Long-term degradation effects of combined Cr-and Si-poisoning on the promising IT-SOFC cathode materials La 0.6 Sr 0.4 CoO 3-δ and La 2 NiO 4+δ were investigated at 700°C in dry and humid atmospheres for subsequent periods of 1000 hours using dcconductivity relaxation measurements. Degradation-induced changes in chemical composition and morphology of the contaminated sample surfaces were studied by atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy with energy and wavelength dispersive X-ray analysis. Upon exposure to humid, Cr-and Si-containing gas flows both materials exhibit a strong decrease of the chemical surface exchange coefficient of oxygen by a factor 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. Post-test analyses confirm large amounts of Cr accompanied by a Sr-enrichment within the first 600 nm of the surface of La 0.6 Sr 0.4 CoO 3-δ , indicating the decomposition of the perovskite phase by SrCrO 4 -formation. For La 2 NiO 4+δ the penetration depth of chromium is significantly less and Cr-traces up to a depth of up to 140 nm were determined by depth profiling. For both compounds silicon was found to spread in small patches across the entire sample surface as determined by elemental mapping analysis.

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Section: Introductionmentioning

confidence: 99%

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

et al. 2015

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“…20-23 When exposed to a hot air flux, these phases generate volatile species. Si contamination from upstream alloys has been reported by other authors, 8 but was not quantified in cells after operation in such studies.…”

Section: Resultsmentioning

confidence: 71%

“…3 Besides bulk impurity, exogenous Si contamination is vehicled in SOFC operation by the reactants, stemming from oils and greases as well as mineral dust. 2,[4][5][6] In particular, cell-proximal system components such as furnace materials [7][8][9] or the common use of quartz reactors can lead to Si contamination. [10][11][12] Although the presence of Si is ubiquitous and influences both the electrolyte and cathode resistivities, 13 the understanding of its effect on electrochemical cathode processes, by a deleterious poisoning of the active catalytic sites for oxygen reduction, is lacking.…”

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confidence: 99%

Glass-Forming Exogenous Silicon Contamination in Solid Oxide Fuel Cell Cathodes

Schuler

Wuillemin

Hessler-Wyser

et al. 2011

Electrochem. Solid-State Lett.

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Spatially resolved analyses, by energy-dispersive X-ray spectroscopy ͑EDS͒ and scanning electron microscopy, allowed the quantification of exogenous Si contamination in a solid oxide fuel cell ͑SOFC͒ cathode after operation. The Si quantification, taking into account the endogenous Si impurity level, correlated well with the expectation from the condensation of Si͑OH͒ 4 vapor, originating from upstream alloy components and saturated in the hot inlet air. At higher resolution, EDS-transmission electron microscopy pointed out the deposition of Si vapor in the form of amorphous SiO 2 , blocking oxygen incorporation into the electrolyte phase within a composite SOFC cathode.In solid oxide fuel cell ͑SOFC͒ technology, silicon ͑Si͒ is, by its insulating and glass-forming properties, a major limitation for electrochemical performance. 1,2 As endogenous impurity in SOFC ceramics, Si is present in raw materials and is introduced by costcutting exercises during powder preparation. 3 Besides bulk impurity, exogenous Si contamination is vehicled in SOFC operation by the reactants, stemming from oils and greases as well as mineral dust. 2,4-6 In particular, cell-proximal system components such as furnace materials 7-9 or the common use of quartz reactors can lead to Si contamination. [10][11][12] Although the presence of Si is ubiquitous and influences both the electrolyte and cathode resistivities, 13 the understanding of its effect on electrochemical cathode processes, by a deleterious poisoning of the active catalytic sites for oxygen reduction, is lacking. 14 Moreover, it is suggested that different Si contamination levels are at least partially responsible for disagreements in the literature related to cathode performance and degradation, 13 as well as for the laboratory specific behavior of SOFC electrodes. 2,15 To enable data correlation from different researches, quantification methods for Si contamination are needed; 16 an area where this study aims to contribute. Energy-dispersive X-ray spectroscopy ͑EDS͒ is employed here as an identification and quantification tool for both endogenous Si impurity levels and Si contamination stemming from exogenous sources.

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“…Powders were uniaxially pressed to pellets, which were sintered at 1250°–1300°C for 4 h. Sample pellets of approximately 1‐mm thickness were cut into four quarters with a diamond saw. Up to eight samples were placed in a sample holder of zirconia and loaded into a horizontal furnace with an alumina lining, to avoid reactions with furnace internals 6 …”

Section: Methodsmentioning

confidence: 99%

“…This perovskite material was chosen for its potentially high flux, combined with a high stability, and flux data for this composition and other related compositions have been presented in a separate paper 5 . The stability of this material in humid atmospheres in the presence of Si is treated in a different paper 6 …”

Section: Introductionmentioning

confidence: 99%

Stability of SrFeO₃‐Based Materials in H₂O/CO₂‐Containing Atmospheres at High Temperatures and Pressures

Kaus

Wiik

Krogh

et al. 2007

Journal of the American Ceramic Society

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The chemical stability of SrFeO3‐based perovskites in H2O‐ and CO2‐containing atmospheres at high temperatures and pressures has been examined. The extent of reaction as a function of pCO2, pH2O, temperature, and time has been determined. Either strontium carbonate or Sr(OH)2·H2O was observed on sample surfaces after exposure. Observation of two different reaction‐rate behaviors could be explained by the formation of different products. The stability of the perovskite has been found to increase when the activity of Sr is decreased. Chemical stability in H2O/CO2 is important to understand in order to use these membrane materials for syngas production.

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Stability of SrFeO3 based materials in the presence of SiOx species in humid atmosphere at high temperatures and pressures

Cited by 10 publications

References 12 publications

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

Glass-Forming Exogenous Silicon Contamination in Solid Oxide Fuel Cell Cathodes

Stability of SrFeO₃‐Based Materials in H₂O/CO₂‐Containing Atmospheres at High Temperatures and Pressures

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Stability of SrFeO3 based materials in the presence of SiOx species in humid atmosphere at high temperatures and pressures

Cited by 10 publications

References 12 publications

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

Long-term stability of the IT-SOFC cathode materials La0.6Sr0.4CoO3−δ and La2NiO4+δ against combined chromium and silicon poisoning

Glass-Forming Exogenous Silicon Contamination in Solid Oxide Fuel Cell Cathodes

Stability of SrFeO3‐Based Materials in H2O/CO2‐Containing Atmospheres at High Temperatures and Pressures

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Stability of SrFeO₃‐Based Materials in H₂O/CO₂‐Containing Atmospheres at High Temperatures and Pressures