Fast oxygen exchange and diffusion kinetics of grain boundaries in Sr-doped LaMnO[subscript 3] thin films
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Yildiz_Fast oxygen.pdf
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Author(s)
Navickas, Edvinas
Huber, Tobias M.
Chen, Yan
Hetaba, Walid
Holzlechner, Gerald
Rupp, Ghislain
Stöger-Pollach, Michael
Friedbacher, Gernot
Hutter, Herbert
Yildiz, Bilge
Alternative Title
Fast oxygen exchange and diffusion kinetics of grain boundaries in Sr-doped LaMnO3 thin films
Date Issued
March 2015
Journal
Physical. Chemistry Chemical Physics
Publisher
Royal Society of Chemistry
Citation
Navickas, Edvinas, Tobias M. Huber, Yan Chen, Walid Hetaba, Gerald Holzlechner, Ghislain Rupp, Michael Stöger-Pollach, Gernot Friedbacher, Herbert Hutter, Yildiz Bilge, and Jurgen Fleig. "Fast oxygen exchange and diffusion kinetics of grain boundaries in Sr-doped LaMnO[subscript 3] thin films." Physical Chemistry Chemical Physics, vol. 17, no 12, March 2015, pp. 7583-8284.
Version
Final published version
Abstract
In this study, the contribution of grain boundaries to the oxygen reduction and diffusion kinetics of La[subscript 0.8]Sr[subscript 0.2]MnO[subscript 3] (LSM) thin films is investigated. Polycrystalline LSM thin films with columnar grains of different grain sizes as well as epitaxial thin films were prepared by pulsed laser deposition. 18O tracer exchange experiments were performed at temperatures from 570 °C to 810 °C and subsequently analyzed by secondary ion mass spectrometry (SIMS). The isotope concentration depth profiles of polycrystalline films clearly indicate contributions from diffusion and surface exchange in grains as well as in grain boundaries. Measured depth profiles were analyzed by finite element modeling and revealed the diffusion coefficients D and oxygen exchange coefficients k of both the grain bulk and grain boundaries. Values obtained for grain boundaries (D[subscript gb] and k[subscript gb]) are almost three orders of magnitude higher than those of the grains (D[subscript g] and k[subscript g]). Hence, grain boundaries may not only facilitate fast oxygen diffusion but also fast oxygen exchange kinetics. Variation of the A-site stoichiometry ((La[subscript 0.8]Sr[subscript 0.2])0.95MnO[subscript 3]) did not lead to large changes of the kinetic parameters. Properties found for epitaxial layers without grain boundaries (Db and kb) are close to those of the grains in polycrystalline layers.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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DOI of Published Version
https://doi.org/10.1039/c4cp05421k
