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p(O2)-T STABILITY DOMAIN OF CUBIC PEROVSKITE Ba0.5Sr0.5Co0.8Fe0.2O3-δ

Abstract

Cubic perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) is one of the mixed ionic-electronic conductors with highest oxygen permeability known to date. It serves as a parent material for the development of functional derivatives for the electrochemical applications including oxygen separation membranes, solid electrolyte cell electrodes, and electrocatalysts for oxygen evolution reaction. The present work is focused on the determination of precise stability boundaries of cubic perovskite BSCF employing coulometric titration technique in combination with thermogravimetric analysis, X-ray and neutron diffraction, and molecular dynamics simulations. Both low-p(O2) and high-p(O2) stability boundaries at 700-950°C were found to correspond to a fixed value of oxygen content in the perovskite lattice: 3-δ = ~2.13 and ~2.515 respectively. The stability limits in this temperature range are expressed by the equations: high-p(O2) boundary: log p(O2) (atm) (± 0.1) = -10150/T (K) + 8.055; low-p(O2) boundary: log p(O2) (atm) (± 0.03) = -20750/T (K) + 4.681. The p(O2)-T phase diagram of the BSCF system under oxidizing conditions is addressed in a wider temperature range and is shown to include the region of precipitation of a “low-temperature” phase occurring at 400-500°C. The fraction of the low-temperature precipitate, which co-exists with the cubic perovskite phase and is stable up to 790-820°C, increases with increasing p(O2) in the range 0.21-1.0 atm.

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Publication details

The article was received on 28 Oct 2017, accepted on 11 Jan 2018 and first published on 11 Jan 2018


Article type: Paper
DOI: 10.1039/C7CP07307K
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    p(O2)-T STABILITY DOMAIN OF CUBIC PEROVSKITE Ba0.5Sr0.5Co0.8Fe0.2O3-δ

    A. A. Yaremchenko, M. Patrakeev, E. N. Naumovich and D. Khalyavin, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C7CP07307K

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