Journal Article

FZJ-2021-01404

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Oxygen Nonstoichiometry and Valence State of Manganese in La 1– x Ca x MnO 3+δ

Heuer, S. A.FZJ* ; Schierholz, R. (Corresponding author)FZJ* ; Alekseev, E.FZJ* ; Peters, L. ; Mueller, D. N.FZJ* ; Duchoň, T.FZJ* ; Vibhu, V.FZJ* ; Tempel, H.FZJ* ; de Haart, L. G. J.FZJ* ; Kungl, H.FZJ* ; Eichel, R.-A.FZJ*RWTH*

2021
ACS Publications Washington, DC

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Please use a persistent id in citations: http://hdl.handle.net/2128/27969  doi:10.1021/acsomega.1c00208

Abstract: Perovskites of the ABO3 type, such as LaMnO3, 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 La1–xCaxMnO3+δ (x = 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.

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Contributing Institute(s):

1. Grundlagen der Elektrochemie (IEK-9)
2. Elektronische Eigenschaften (PGI-6)

Research Program(s):

1. 122 - Elektrochemische Energiespeicherung (POF4-122) (POF4-122)
2. 1232 - Power-based Fuels and Chemicals (POF4-123) (POF4-123)

Appears in the scientific report 2021

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