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dc.contributor.authorRuhl, Rian
dc.contributor.authorSong, Jia
dc.contributor.authorThoréton, Vincent
dc.contributor.authorSingh, Sathya Prakash
dc.contributor.authorWiik, Kjell
dc.contributor.authorLarring, Yngve
dc.contributor.authorBouwmeester, Henny J. M.
dc.identifier.citationPhysical Chemistry, Chemical Physics - PCCP. 2019, 21 (39), 21824-21835.nb_NO
dc.description.abstractCalcium manganite-based perovskite-type oxides hold promise for application in chemical looping combustion processes and oxygen transport membranes. In this study, we have investigated the structure, electrical conductivity and oxygen transport properties of perovskite-type oxides CaMn1−x−yTixFeyO3−δ. Distinct from previous work, data of high-temperature X-ray diffraction (HT-XRD) in the temperature range 600–1000 °C (with intervals of 25 °C) demonstrates that CaMnO3−δ (CM) transforms from orthorhombic to a mixture of orthorhombic and tetragonal phases between 875 °C and 900 °C. Rietveld refinements show the formation of a pure tetragonal phase at 975 °C and of a pure cubic phase at 1000 °C. Partial substitution of manganese by iron and/or titanium to yield CaMn0.875Ti0.125O3−δ (CMT), CaMn0.85Fe0.15O3−δ (CMF) or CaMn0.725Ti0.125Fe0.15O3−δ (CMTF) leads to different phase behaviours. While CMT remains orthorhombic up to the highest temperature covered by the HT-XRD experiments, CMF and CMTF undergo an orthorhombic → tetragonal → cubic sequence of phase transitions. Electrical conductivity relaxation measurements are conducted to determine the chemical diffusion coefficient (Dchem) and the surface exchange coefficient (kchem) of the materials. The results demonstrate that oxygen transport is hindered in the tetragonal phase, when occurring, which is attributed to a possible ordering of oxygen vacancies. The small polaron electrical conductivity of CM in the cited temperature range is lowered upon partial manganese substitution, by about 10% for CMF and up to half an order of magnitude for CMT and CMTF.nb_NO
dc.publisherRoyal Society of Chemistrynb_NO
dc.rightsNavngivelse-Ikkekommersiell 4.0 Internasjonal*
dc.subjectOxygen transportnb_NO
dc.titleStructure, electrical conductivity and oxygen transport properties of perovskite-type oxides CaMn1−x−yTixFeyO3−δnb_NO
dc.typeJournal articlenb_NO
dc.typePeer reviewednb_NO
dc.rights.holderOpen Access Article. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.nb_NO
dc.source.journalPhysical Chemistry, Chemical Physics - PCCPnb_NO
cristin.unitnameBærekraftig energiteknologi

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Navngivelse-Ikkekommersiell 4.0 Internasjonal
Except where otherwise noted, this item's license is described as Navngivelse-Ikkekommersiell 4.0 Internasjonal