Oxygen non-stoichiometry and mixed conductivity of La0.5Sr0.5Fe1–xMnxO3–δ

Oxygen non-stoichiometry, thermal expansion, and high-temperature transport properties of perovskite-type La 0.5 Sr 0.5 Fe 1– x Mn x O 3– δ , where x  = 0, 0.10, 0.17, 0.25, and 0.33 have been studied in the oxygen partial pressure range 10 −19 to 0.5 atm. The major trends observed under oxidizing a...

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Bibliographic Details
Published in:Journal of solid state electrochemistry 2016, Vol.20 (1), p.225-234
Main Authors: Markov, A. A., Chesnokov, K. Yu, Patrakeev, M. V., Leonidov, I. A., Chukin, A. V., Leonidova, O. N., Kozhevnikov, V. L.
Format: Article
Language:English
Subjects:
Analytical Chemistry
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Condensed Matter Physics
Electrochemistry
Energy Storage
Original Paper
Physical Chemistry
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Summary:Oxygen non-stoichiometry, thermal expansion, and high-temperature transport properties of perovskite-type La 0.5 Sr 0.5 Fe 1– x Mn x O 3– δ , where x  = 0, 0.10, 0.17, 0.25, and 0.33 have been studied in the oxygen partial pressure range 10 −19 to 0.5 atm. The major trends observed under oxidizing and reducing conditions were found to exhibit substantial differences due to changes in the manganese oxidation state. The high p O 2 range is characterized with replacement of Fe 4+ by Mn 4+ cations, which results in the decreasing concentration of mobile p -type electronic carriers, oxygen non-stoichiometry, and thermal expansion. The oxygen pressure decrease below 10 −5  atm is accompanied with gradual reduction of manganese to Mn 3+ /Mn 4+ mixed oxidation state, followed by larger variations in the non-stoichiometry, electrical conductivity, and thermal expansion. The observed increase in the oxygen ion conductivity with manganese content can be explained as a consequence of strong Mn preference for fivefold oxygen coordination in the oxygen-deficient perovskite lattice, which promotes the formation of oxygen vacancies available for anion diffusion. The calculated oxygen permeation fluxes through La 0.5 Sr 0.5 Fe 0.67 Mn 0.33 O 3– δ membranes at 950 °C become higher compared with La 0.5 Sr 0.5 FeO 3– δ , which may be advantageous for application in the integrated processes of oxygen separation, partial hydrocarbon oxidation, and hydrogen production.
ISSN:1432-8488
1433-0768
DOI:10.1007/s10008-015-3027-0