Determination of Oxygen Nonstoichiometry and Diffusivity in Mixed Conducting Oxides by Oxygen Coulometric Titration I: Chemical Diffusion in La0.8Sr0.2CoO3-δ

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Lankhorst, Martijn H.R. and Bouwmeester, H.J.M. (1997) Determination of Oxygen Nonstoichiometry and Diffusivity in Mixed Conducting Oxides by Oxygen Coulometric Titration I: Chemical Diffusion in La0.8Sr0.2CoO3-δ. Journal of the Electrochemical Society, 144 (4). pp. 1261-1267. ISSN 0013-4651

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Abstract:Oxygen coulometric titration has been applied to measure chemical diffusion in La0.8Sr0.2CoO3-δ between 700 and 1000°C. The transient current response to a potentiostatic step has been transformed from the time domain to the frequency domain. The equivalent circuit used to fit the resulting impedance data contains the element that describes the finite-length diffusion of oxygen into the sample specimen. Other elements included are the gas-phase capacitance and the sum of the gas-phase diffusion resistance and that associated with the limited surface exchange kinetics of the sample. The chemical diffusion coefficient of perovskite La0.8Sr0.2CoO3-δ has been determined as a function of temperature and oxygen partial pressure. Its value can be represented by ~D (cm2/s) = 5.91 x exp [(-135 kJ/mol)/RT], and turns out to be practically independent of oxygen partial pressure in the range 10-2 - 0.209 bar.
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Copyright:The Electrochemical Society
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Science and Technology (TNW)
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Link to this item:http://purl.utwente.nl/publications/61585
Official URL:http://dx.doi.org/10.1149/1.1837580
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Metis ID: 106487