Effect of phase transition on high-temperature electrical properties of GdBaCo₂O_5 + x layered perovskite

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• 作者：A. Tarancó ; n ; D. Marrero-Ló ; pez ; J. Peñ ; a-Martí ; nez ; J.C. Ruiz-Morales ; P. N&#xfa ; ñ ; ez
• 关键词：SOFC ; Cathode ; Layered perovskite ; GBCO ; Phase transition
• 刊名：Solid State Ionics
• 出版年：2008
• 期刊代码：96_01672738
• 类别：ch
• 出版时间：July 2008
• 卷：179
• 期：17-18
• 页码：611-618
• 文件大小：925 K

摘要

The effect of the structural phase transition on the electrical and electrochemical properties of GdBaCo₂O_{5 + x} has been analysed in order to evaluate its suitability as an electrode material for high-temperature applications, in particular as a cathode for Solid Oxide Fuel Cells (SOFCs). X-ray diffraction evolution with the temperature and differential scanning calorimetry were used to determine structural features of the phase transition, e.g. phases symmetry, thermal expansion coefficients, transition temperatures and enthalpy changes. Four-probe dc-electrical measurements of dense pellets of GdBaCo₂O_{5 + x} and electrochemical characterization by means of impedance spectroscopy as a part of a symmetrical cell (GdBaCo₂O_{5 + x}/La_0.9Sr_0.1Ga_0.8Mg_0.2O_{3 − δ}/GdBaCo₂O_{5 + x}) were carried out yielding high stability of this material across the mentioned phase transition. The thermal relation of the oxygen stoichiometry with the structural and electrical features revealed the importance of the oxygenation/deoxygenation processes taking place in this material.