abstract
Potassium-substituted SrFeO3-delta for possible application as oxygen evolution electrode in alkaline or molten salt media was prepared by mechanical activation and characterized by X-ray diffraction, dilatometric and thermogravimetric analysis, Mossbauer spectroscopy, and electrical conductivity measurements. Room temperature mechanical activation of a mixture of oxide precursors with subsequent thermal treatments at 700-900 degrees C results in the formation of Sr(0.9)Ka(0.1)FeO(3-delta) with tetragonal perovskite-like structure. Such allows to decrease the synthesis temperature, if compared to the conventional solid-state route, and to prevent possible volatilization of potassium. The results of Mossbauer spectroscopy studies indicate that the oxygen nonstoichiometry in the samples annealed in air at 900-1100 degrees C with subsequent rapid cooling vary in the range delta=0.30-0.32. The electrical conductivity in air exhibits a metal-like behaviour at temperatures above 400 degrees C and semiconductor behaviour in the low-temperature range, reaching 13-30 S/cm under prospective operation conditions for alkaline electrolyzers (<= 90 degrees C). (C) 2012 Elsevier Inc. All rights reserved.
keywords
OXIDE FUEL-CELLS; OXYGEN STOICHIOMETRY; CATHODE MATERIALS; SRFEO3-DELTA; CONDUCTIVITY; PEROVSKITES; PERMEATION; STABILITY; CERAMICS; SIZE
subject category
Chemistry
authors
Monteiro, JF; Waerenborgh, JC; Kovalevsky, AV; Yaremchenko, AA; Frade, JR
our authors
Aleksey Yaremchenko
Principal Researcher
Andrei Kavaleuski
Principal Researcher
Jorge Ribeiro Frade
Retired Professor
José Filipe Pinto Monteiro
PhD Studentacknowledgements
The work was supported by the European Union's Research Fund for Coal and Steel (RFCS) research programme, under the grant agreement IERO-RSF-PR-09099, by the Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), under the grant agreement SFRH/BD/68290/2010, and by the Fundo Social Europeu (FSE, Uniao Europeia).