Heuer Sabrina A, Schierholz Roland, Alekseev Evgeny V, Peters Lars, Mueller David N, Duchoň Tomáš, Vibhu Vaibhav, Tempel Hermann, de Haart Lambertus G J, Kungl Hans, Eichel Rüdiger-A
Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, DE-52425 Jülich, Germany.
Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany.
ACS Omega. 2021 Apr 2;6(14):9638-9652. doi: 10.1021/acsomega.1c00208. eCollection 2021 Apr 13.
Perovskites of the ABO type, such as LaMnO, can be used as air electrodes in solid oxide fuel cells and electrolyzers. Their properties can be tuned by A- and B-site substitutions. The influence of La substitution by Ca on the oxygen nonstoichiometry has been investigated frequently, but the results depend highly on the synthesis and atmospheric conditions. In this work, a series of La Ca MnO ( = 0-0.5) was synthesized using conventional solid-state synthesis under an air atmosphere. The structures of the materials were studied in detail with powder X-ray diffraction. The initial oxygen nonstoichiometries were determined using thermogravimetric reduction. The samples were subsequently analyzed in terms of defect chemistry in dependence of temperature, atmosphere, and Ca content via thermogravimetric analysis. The changes in the manganese charge states were investigated by X-ray absorption near-edge spectroscopy experiments. The influence of intrinsic and extrinsic effects on the Mn-valence state of the differently Ca-substituted samples as calculated from thermogravimetric analysis and as determined directly from X-ray absorption near-edge spectroscopy is presented.
ABO型钙钛矿，如LaMnO，可作为固体氧化物燃料电池和电解槽中的空气电极。其性能可通过A位和B位取代进行调节。钙对镧取代的氧非化学计量比的影响已被频繁研究，但结果高度依赖于合成和大气条件。在这项工作中，采用常规固态合成法在空气气氛下合成了一系列LaCaMnO（=0-0.5）。用粉末X射线衍射详细研究了材料的结构。使用热重还原法测定初始氧非化学计量比。随后通过热重分析根据温度、气氛和钙含量对样品进行缺陷化学分析。通过X射线吸收近边光谱实验研究了锰电荷态的变化。给出了根据热重分析计算以及直接由X射线吸收近边光谱测定的本征和非本征效应对不同钙取代样品的锰价态的影响。
