Electrochemically driven cation segregation in the mixed conductor La_0.6Sr_0.4Co_0.2Fe_0.8O_{3 鈭?#xa0;未}

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• 作者：M. Finsterbusch^a ; ^b ; ; A. Lussier^a ; J.A. Schaefer^b ; Y.U. Idzerda^a
• 关键词：Fuel cell ; MIEC ; LSCF ; Strontium ; Segregation ; X-ray absorption
• 刊名：Solid State Ionics
• 出版年：2012
• 期刊代码：96_01672738
• 类别：ch
• 出版时间：29 March, 2012
• 卷：212
• 期：Complete
• 页码：77-80
• 文件大小：274 K

摘要

Strontium segregation as function of electrochemical environment is measured for La_0.6Sr_0.4Co_0.2Fe_0.8O_{3 鈭?#xA0;未} using X-ray absorption spectroscopy. Gaseous Cr is used as a tracer to distinguish the bulk Sr from the segregated SrO at the surface via formation of SrCrO₄. From the SrCrO₄ to Cr₂O₃ ratio, the impact of cathodic and anodic overpotentials on Sr segregation is determined. While low anodic overpotentials were found to inhibit Sr segregation, higher overpotentials promote increased Sr segregation at the anode compared to the cathode. Oxygen vacancy concentration variations, caused by the overpotentials existing during operation, are identified as the driving mechanism for the Sr out-diffusion. Using this proposed Sr segregation mechanism, possible mitigation strategies are suggested.