Defect formation and transport in mixed-conducting La0.90Sr0.10Al0.85-xFexMg0.15O3-delta

resumo

The redox behavior of perovskite-type La0.9Sr0.10Al0.85-xFexMg0.15O3-delta (x = 0.20-0.40) mixed conductors was analyzed by the Mossbauer spectroscopy and measurements of the total conductivity and Seebeck coefficient in the oxygen partial pressure range from 10(-20) to 0.5 atm at 1023-1223K. The results combined with oxygen-ion transference numbers determined by the faradaic efficiency technique in air, were used to calculate defect concentrations, mobilities, and partial ionic and p- and n-type electronic conductivities as a function of oxygen pressure. The redox and transport processes can be adequately described in terms of oxygen intercalation and iron disproportionation reactions, with the thermodynamic functions independent of defect concentrations. No essential delocalization of the electronic charge carriers was found. The oxygen non-stoichiometry values estimated from the conductivity vs. p(O-2) dependencies, coincide with those evaluated from the Mossbauer spectra. (c) 2006 Elsevier Ltd. All rights reserved.

palavras-chave

MOSSBAUER-SPECTROSCOPY; SEEBECK COEFFICIENT; CERAMICS; OXIDE; FE; PEROVSKITES; NI

categoria

Chemistry; Physics

autores

Tsipis, EV; Waerenborgh, JC; Kharton, VV; Naumovich, EN; Frade, JR

nossos autores

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