Redox behavior of acceptor-doped La(Al,Fe)O3-delta
authors Tsipis, EV; Kharton, VV; Waerenborgh, JC; Rojas, DP; Naumovich, EN; Frade, JR
nationality International
journal JOURNAL OF ALLOYS AND COMPOUNDS
author keywords point defects; electronic transport; ionic conduction; X-ray and gamma-ray spectroscopies
keywords PEROVSKITE-TYPE OXIDES; ELECTRONIC CONDUCTIVITY; OXYGEN NONSTOICHIOMETRY; MOSSBAUER-SPECTROSCOPY; SEEBECK COEFFICIENT; VACANCIES
abstract In order to study the behavior of perovskite-type phases containing similar fractions of transition metal cations and ions with stable oxidation state in the B sublattice, the defect formation processes in mixed-conducting Lac(0.90)Sr(0.10)Al(0.45)Fe(0.40)Mg(0.15)O(3-delta) were analyzed using the measurements of total conductivity in the oxygen partial pressure range from 10(-20) to 0.5 atm, at 1073-1223 K. The results, in combination with Mossbauer spectroscopy data and ion transference numbers determined by the faradaic efficiency technique in air, show that increasing p(O-2) leads to decreasing oxygen ionic conductivity, whilst no essential delocalization of the electronic charge carriers is observed. The variations of partial ionic and p- and n-type electronic conductivities can be adequately described by equilibrium processes of oxygen intercalation and iron disproportionation with the thermodynamic functions independent of defect concentrations. The hole mobility is also concentration-independent and has an activation energy of 37 +/- KJ/mol, suggesting that the p-type electronic transport occurs via a small-polaron mechanism within the whole p(O-2) range studied. The values of hole concentration derived from the conductivity data are in excellent agreement with the Mossbauer spectroscopy results. (c) 2005 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE SA
issn 0925-8388
year published 2006
volume 413
issue 1-2
beginning page 244
ending page 250
digital object identifier (doi) 10.1016/j.jallcom.2005.05.045
web of science category Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering
subject category Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
unique article identifier WOS:000236312900040
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journal impact factor 4.65
5 year journal impact factor 4.082
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