Degradation of La0.6Sr0.4Fe0.8Co0.2O3-δ in carbon dioxide and water atmospheres

• Published in: Journal of the Electrochemical Society 1999-04, Vol.146 (4), p.1305-1309
• Main Authors: BENSON, S. J, WALLER, D, KILNER, J. A
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Membranes
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1391762

The mixed ionic-electronic conductor La0.6Sr0.4Co0.2Fe0.8O3- delta (LSCF) is a candidate for use as the membrane material in the pressure- driven air separator. However the long-term stability of these materials is a major concern for the commercial realisation of these devices. In an attempt to assess the stability of the material under realistic operating conditions for such a system, samples of LSCF were exposed to atmospheres of H2O/CO2/O2 at 750 C. Degradation of the material was studied using Raman spectroscopy and XRD. Oxygen isotope exchange combined with SIMS was used to observe the effect of the presence of CO2 and H2O on the oxygen diffusivity and surface exchange. It was observed that oxygen surface exchange was actually enhanced in the presence of CO2 and H2O, during the duration of the study, although the oxygen diffusivity remained the same. The presence of volatile chromia species was found to significantly increase the rate of degradation of the ceramic. 19 refs.