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Persistent URL	http://purl.org/net/epubs/work/36243
Record Status	Checked
Record Id	36243
Title	Phase stability and oxygen non-stoichiometry of SrCo_0.8Fe_0.2O3−δ measured by in situ neutron diffraction
Contributors	S McIntosh (Inorganic Material Science, Department of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands), JF Vente (Energy Research Centre of the Netherlands, 1755 ZG Petten, Netherlands ), WG Haije (Energy Research Centre of the Netherlands, 1755 ZG Petten, Netherlands ), DHA Blank (Inorganic Material Science, Department of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands), HJM Bouwmeester (Inorganic Material Science, Department of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands)
Abstract	The phase stability, oxygen stoichiometry and expansion properties of SrCo0.8Fe0.2O3−δ (SCF) were determined by in situ neutron diffraction between 873 and 1173 K and oxygen partial pressures of 5 × 10− 4 to 1 atm. At a pO2 of 1 atm, SCF adopts a cubic perovskite structure, space group Pm3¯m, across the whole temperature range investigated. At a pO2 of 10− 1 atm, a two-phase region exists below 922 K, where the cubic perovskite phase coexists with a vacancy ordered brownmillerite phase, Sr2Co1.6Fe0.4O5, space group Icmm. A pure brownmillerite phase is present at pO2 of 10− 2 and 5 × 10− 4 atm below 1020 K. Above 1020 K, the brownmillerite phase transforms to cubic perovskite through a two-phase region with no brownmillerite structure observed above 1064 K. Large distortion of the BO6 (B = Co, Fe) octahedra is present in the brownmillerite structure with apical bond lengths of 2.2974(4) Å and equatorial bond lengths of 1.9737(3) Å at 1021 K and a pO2 of 10− 2 atm. SCF is highly oxygen deficient with a maximum oxygen stoichiometry, 3 − δ, measured in this study of 2.58(2) at 873 K and a pO2 of 1 atm and a minimum of 2.33(2) at 1173 K and a pO2 of 5 × 10− 4 atm. Significant differences in lattice volume and expansion behavior between the brownmillerite and cubic perovskite phases suggest potential difficulties in thermal cycling of SrCo0.8Fe0.2O3−δ membranes.
Organisation	CCLRC , ISIS-GEM
Keywords	Materials , Neutron diffraction , Oxygen non-stoichiometry , Chemical expansion , Brownmillerite¿perovskite phase transition , Membranes , SrCo0.8Fe0.2O3−δ
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Language	English (EN)

Type	Details	URI(s)	Local file(s)	Year
Journal Article	Solid State Ionics 177, no. 9-10 (2006): 833-842.	doi:10.1016/j.ssi.2006.02.017		2006