Phase stability of BSCF in low oxygen partial pressures
- Kazuo Inamori School of Engineering, Alfred University, Alfred, NY 14802 (United States)
In situ X-ray diffraction has been used to investigate the phase stability of barium strontium cobalt iron oxide (BSCF) with the formula Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1-x}Co{sub x}O{sub 3-{delta}} (x=0, 0.2, 0.4, 0.6, 0.8, and 1). The thermal decomposition processes in both low partial pressures of oxygen (air -10{sup -5} atm pO{sub 2}) and in reducing conditions have been detailed. BSCF manifests excellent stability down to 10{sup -5} atm pO{sub 2}; however, it decomposes through a complex series of oxides under reducing conditions. Increasing the cobalt content results in a decrease in the temperature range of stability of the material under 4% H{sub 2} in N{sub 2}, with the initial decomposition taking place at 375, 425, 550, 600, 650 and 675 deg. C, for x=1, 0.8, 0.6, 0.4, 0.2 and 0, respectively. Further, the thermal expansion is a strong function of the oxygen activity and Co content. The x=0, 1 end member, BSC, undergoes a phase transition from rhombohedral to cubic symmetry at {approx}800 deg. C under 10{sup -5} atm pO{sub 2}, resulting in an ideal perovskite with a=3.9892(3) A at room temperature. - Graphical abstract: The phase stability of the fuel cell cathode Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1-x}Co{sub x}O{sub 3-{delta}} in low pO{sub 2} and high temperature has been investigated using in situ X-ray diffraction. Both stability and thermal expansion coefficient were found to increase with increasing iron content. Decomposition products under reducing conditions have been identified.
- OSTI ID:
- 21043927
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 3; Other Information: DOI: 10.1016/j.jssc.2008.01.010; PII: S0022-4596(08)00026-1; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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