Influence of order-disorder transitions on oxygen permeability through selected nonstoichiometric perovskite-type oxides

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Kruidhof, H. and Bouwmeester, H.J.M. and Doorn van, R.H.E. and Burggraaf, A.J. (1993) Influence of order-disorder transitions on oxygen permeability through selected nonstoichiometric perovskite-type oxides. Solid State Ionics, 63-65 . pp. 816-822. ISSN 0167-2738

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Abstract:New results on the oxygen permeability of perovskite-type oxides SrCo0.8B'0.2O3¿¿ (with B'=Cr, Fe, Co and Cu) and La0.6Sr0.4CoO3¿¿ are presented. The occurrence of order-disorder transitions at elevated temperatures (790¿940°C) in these phases has been confirmed by DSC measurements and, in some cases, by X-ray powder diffraction of samples either slowly cooled or quenched from high temperature after annealing in different atmospheres. The oxygen permeability found upon exposing opposite sides of sealed disc specimens to a stream of air and of helium, respectively, increases sharply (between 5¿6 orders of magnitude up to 0.3¿3×10¿7 mol cm¿2s¿1) at the onset of the transition from a low-temperature vacancy-ordered state to defec t perovskite, except for SrCo0.8Fe0.2O3¿¿. In the latter case only a slight anomaly is found in the Arrhenius plot of th e oxygen permeability at 790°C. The comparatively high oxygen flux through SrCo0.8Fe0.2O3¿¿ observed at intermediate tempe ratures is interpreted in terms of a two-phase mixture of a vacancy-ordered state and disordered perovskite, while above 790°C the sample is single-phase of defect perovskite structure.
Item Type:Article
Copyright:© 1993 Elsevier Science
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Science and Technology (TNW)
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Link to this item:http://purl.utwente.nl/publications/57192
Official URL:http://dx.doi.org/10.1016/0167-2738(93)90202-E
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