, Volume 9, Issue 3-4, pp 189-194

Release and uptake of oxygen in mixed-conducting SOFC cathode materials measured by temperature-programmed methods

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Abstract

Oxygen uptake and release in A1−aA′aB1−bB′bO3−δ perovskite-type oxides with A=La, Pr; A′=Sr; B=Fe, Mn, B′=Co was examined by means of temperature-programmed oxidation (TPO) and temperature-programmed reduction (TPR). The investigated powders were prepared by spray-drying and were annealed at 900 to 1300 °C. In the TPR profiles, two processes of oxygen release from these materials were observed. The first TPR peak was regarded as surface adsorption, while the second one was considered to result from oxygen bulk diffusion. The oxygen volumes involved and the activation energy for the oxygen diffusion were determined from the TPO and TPR profiles and varied between 0.53 and 2.2 eV for the ferrites and manganites, respectively.

Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15–21, 2002.