Effects of A/B-ratio in strontium doped lanthanum cobaltite

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EFFECTS OF A/B-RATIO IN STRONTIUM DOPED LANTHANUM COBALTITE Martin Søgaard a;b, Peter V. Hendriksen a, Dorthe Lybye a, Mogens Mogensen a and Torben Jacobsen b aRisø National Laboratory, Materials Research Department, Frederiksborgvej 399, DK-4000 Roskilde, Denmark bTechnical University of Denmark, Department of Chemistry, DK-2800 Kgs. Lyngby, Denmark ABSTRACT The electrical conductivity of (La0.85Sr0.15)sCoO3-δ, s = 0.98; s = 1.00; s = 1.02 has been measured. The electrical conductivity of the composition s = 0.98 was significantly higher than those of the other two materials at temperatures below 400°C. The chemical diffusion coefficient, DChem, and the apparent surface exchange coefficient, kEx, were measured using electrical conductivity relaxation. The compositions s = 1.02 and s = 0.98 had within the uncertainty the same surface exchange coefficient. kEx was approximately 3 times larger for the composition s = 0.98. It is speculated that the Co-rich material has a surface layer richer in cobalt, which improves the electrochemical activity. DChem, was the same for the compositions s = 0.98 and s = 1.00, whereas it was significantly lower for the s = 1.02 material by approximately 25%. The activation energy for the vacancy diffusion coefficient, DV, was calculated to 75.2 kJ mol-1 for the s = 1.02 composition. Oxygen permeation measurements were carried out on the s = 1.02 composition using an oxygen-pump. The results were in excellent agreement with fluxes calculated from the measured DChem and kEx values using the Wagner equation combined with surface exchange reactions.
Original languageEnglish
Publication date2004
Publication statusPublished - 2004
Event206th Meeting of the Electrochemical Society : 5th International Symposium on Ionic and 5th International Symposium on Ionic and mixed Conducting Ceramics - Honolulu, United States
Duration: 3 Oct 20048 Oct 2004
Conference number: 206


Conference206th Meeting of the Electrochemical Society
Country/TerritoryUnited States


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