Transport numbers and oxygen permeability of SrCe(Y)O-3-based ceramics under oxidising conditions
authors Kharton, VV; Marozau, IP; Mather, GC; Naumovich, EN; Frade, JR
nationality International
journal ELECTROCHIMICA ACTA
author keywords strontium cerate; protonic conductor; mixed conductivity; oxygen permeability; Faradaic efficiency
keywords PROTON-CONDUCTING CERAMICS; DOPED STRONTIUM CERATE; SOLID-SOLUTIONS; CARBON-DIOXIDE; FUEL-CELLS; PEROVSKITES; OXIDES; DEFECT; SRCE0.95Y0.05O3-DELTA; MICROSTRUCTURE
abstract Partial conductivities in the SrCe(Y)O3-delta System have been studied in oxidising conditions in the temperature range 923-1273 K. Compositions with variable Y content (5 and 10 at.%), Sr deficiency (3 at.%), and with the addition of Fe2O3 as sintering aid (2 mol%) were analysed. A modified Faradaic efficiency method and oxygen permeation measurements were employed to appraise the oxide-ionic transport. Oxide-ion transference numbers in air lie in the range 0.19-0.80 and decrease with increasing temperature in the range 973-1223 K. Modelling of total conductivity as a function of oxygen partial pressure (P(02)) Confirmed that protonic transport is minor under the studied conditions. SrCe0.95Y0.05O3-delta exhibits greater oxide-ion conductivity than SrCe0.9Y0.1O3-delta, indicative of dopant-vacancy association at high dopant contents. Conversely, oxygen permeability is slightly higher for SrCe0.9Y0.1O3-delta as a result of faster surface-exchange kinetics. The oxygen flux through Fe-free membranes is dominated by the bulk in low P(O-2) gradients, when the permeate-side P(O-2) is higher than 0.03 atm, but surface exchange plays an increasing role with increasing p(O-2) gradient. Addition of Fe2O3 to SrCe(Y)O3-delta lowers the sintering temperature by similar to 100 K but results in the formation of intergranular second phases which block oxide-ionic and electronic transport, and thus oxygen permeation. The average thermal expansion coefficients (TECs) are (10.8-11.6) x 10(-6) K-1 in the temperature range 373-1373 K for all studied compositions. (c) 2006 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0013-4686
year published 2006
volume 51
issue 28
beginning page 6389
ending page 6399
digital object identifier (doi) 10.1016/j.electacta.2006.04.023
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000240855100023
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journal impact factor 6.215
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