Oxygen transport in ferrite-based ceramic membranes: Effects of alumina sintering aid

authors	Kharton, VV; Shaula, AL; Snijkers, FMM; Cooymans, JFC; Luyten, JJ; Marozau, IP; Viskup, AP; Marques, FMB; Frade, JR
nationality	International
journal	JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords	perovskites; sintering; ionic conductivity; membranes; Sr(Fe, Al)O(3); (La, Sr)(Fe,Ga)O(3)
keywords	ION-TRANSPORT; METHANE OXIDATION; THERMAL-EXPANSION; CONDUCTIVITY; PEROVSKITES; STABILITY; BEHAVIOR; PHASE; CERIA; GAS
abstract	Moderate additions of Al(2)O(3) to strontium ferrite-based mixed conductors, such as SrFe(0.7)Al(0.3)O(3-delta) and La(0.2)Sr(0.8)Fe(0.8)Ga(0.2)O(3-delta) with the composition close to the solid solution formation limits, make it possible to improve ceramics sinterability, to increase oxygen permeability and to decrease thermal expansion. These effects are associated with the segregation of alumina-rich phases, primarily SrAl(2)O(4), and the formation of A-site cation-deficient perovskite. The improved properties of the SrFe(0.7)Al(0.3)O(3)-based material were used to fabricate high-quality tubular membranes for methane conversion reactors. Similar enhancement in sinterability is also observed for another promising parent material of mixed-conducting membranes, La(0.5)Sr(0.5)FeO(3-delta). However, extensive dissolution of Al(3+), cations in the iron sublattice, creation of A-site vacancies and changing the La:Sr concentration ratio all lead to decreasing ionic transport in La(0.5)Sr(0.5)FeO(3-delta). As a result, additions of either Al(2)O(3) or SrAlO(4) have a deteriorating influence on the oxygen permeation fluxes through La(0.5)Sr(0.5)FeO(3)-based ceramics. (c) 2005 Elsevier Ltd. All rights reserved.
publisher	ELSEVIER SCI LTD
issn	0955-2219
year published	2006
volume	26
issue	16
beginning page	3695
ending page	3704
digital object identifier (doi)	10.1016/j.jeurceramsoc.2005.10.013
web of science category	Materials Science, Ceramics
subject category	Materials Science
unique article identifier	WOS:000241841300025