Knöchel, Patrick L. ; Keenan, Philip J. ; Loho, Christoph ; Reitz, Christian ; Witte, Ralf ; Knight, Kevin S. ; Wright, Adrian J. ; Hahn, Horst ; Slater, Peter R. ; Clemens, Oliver (2016)
Synthesis, structural characterisation and proton conduction of two new hydrated phases of barium ferrite BaFeO2.5−x(OH)2x.
In: Journal of Materials Chemistry A, 4 (9)
doi: 10.1039/c5ta06383c
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Materials exhibiting mixed electronic and proton conductivity are of great interest for applications ranging from electrodes for proton conducting ceramic fuel cells to hydrogen separation membranes. In this work, we report a detailed investigation of the effect of water incorporation in BaFeO2.5 on the structure and conductivity. BaFeO2.5 is shown to be topochemically transformed to two different hydrated modifications, low-water (LW-) and high-water (HW-) BaFeO2.5. A combined analysis of neutron and X-ray diffraction data was used to determine the crystal structure of LW-BaFeO2.5 (BaFeO2.33(OH)0.33), which shows a unique ordering pattern of anion vacancies for perovskite type compounds, with structural relaxations around vacancies being similar to the chemically similar compound BaFeO2.33F0.33. Approximate proton positions were determined using the bond valence method. Conductivity studies of hydrated and pure BaFeO2.5 (with additional comparison to oxidized BaFeO2.5) show a significant enhancement of the conductivity on water incorporation, which can be attributed to proton conductivity. This is the first report of significant grain proton conduction (∼10−6 to 10−7 S cm−1) in an iron based perovskite. Water uptake is further shown to be completely reversible, with reformation of BaFeO2.5 when heating the compound to temperatures above ∼450 K under Ar.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2016 |
| Autor(en): | Knöchel, Patrick L. ; Keenan, Philip J. ; Loho, Christoph ; Reitz, Christian ; Witte, Ralf ; Knight, Kevin S. ; Wright, Adrian J. ; Hahn, Horst ; Slater, Peter R. ; Clemens, Oliver |
| Art des Eintrags: | Bibliographie |
| Titel: | Synthesis, structural characterisation and proton conduction of two new hydrated phases of barium ferrite BaFeO2.5−x(OH)2x |
| Sprache: | Englisch |
| Publikationsjahr: | September 2016 |
| Verlag: | Royal Society of Chemistry |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Journal of Materials Chemistry A |
| Jahrgang/Volume einer Zeitschrift: | 4 |
| (Heft-)Nummer: | 9 |
| DOI: | 10.1039/c5ta06383c |
| URL / URN: | https://doi.org/10.1039/c5ta06383c |
| Kurzbeschreibung (Abstract): | Materials exhibiting mixed electronic and proton conductivity are of great interest for applications ranging from electrodes for proton conducting ceramic fuel cells to hydrogen separation membranes. In this work, we report a detailed investigation of the effect of water incorporation in BaFeO2.5 on the structure and conductivity. BaFeO2.5 is shown to be topochemically transformed to two different hydrated modifications, low-water (LW-) and high-water (HW-) BaFeO2.5. A combined analysis of neutron and X-ray diffraction data was used to determine the crystal structure of LW-BaFeO2.5 (BaFeO2.33(OH)0.33), which shows a unique ordering pattern of anion vacancies for perovskite type compounds, with structural relaxations around vacancies being similar to the chemically similar compound BaFeO2.33F0.33. Approximate proton positions were determined using the bond valence method. Conductivity studies of hydrated and pure BaFeO2.5 (with additional comparison to oxidized BaFeO2.5) show a significant enhancement of the conductivity on water incorporation, which can be attributed to proton conductivity. This is the first report of significant grain proton conduction (∼10−6 to 10−7 S cm−1) in an iron based perovskite. Water uptake is further shown to be completely reversible, with reformation of BaFeO2.5 when heating the compound to temperatures above ∼450 K under Ar. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialdesign durch Synthese 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Gemeinschaftslabor Nanomaterialien |
| Hinterlegungsdatum: | 22 Mär 2017 11:10 |
| Letzte Änderung: | 29 Jan 2019 07:50 |
| PPN: | |
| Sponsoren: | Neutron diffraction beam time at ISIS was provided by the Science and Technology Facilities Council (STFC). |
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