Oxygen transport and chemical compatibility with electrode materials in scheelite-type LaWxNb1-xO4+x/2 ceramic electrolyte

authors	Canu, G; Buscaglia, V; Ferrara, C; Mustarelli, P; Patricio, SG; Rondao, AIB; Tealdi, C; Marques, FMB
nationality	International
journal	JOURNAL OF ALLOYS AND COMPOUNDS
author keywords	Ceramics; LaWxNb1-xO4+x/2; Electrolyte; Chemical compatibility; Oxygen-ion conductor
keywords	OXIDE FUEL-CELLS; ELECTRICAL-CONDUCTIVITY; MODULATED STRUCTURE; CRYSTAL-STRUCTURE; ION CONDUCTION; DIFFRACTION; LANBO4; PR; LA
abstract	LaWxNb1-xO4+x/2 ceramics (x = 0.16) were prepared via a solid state route and studied with respect to phase stability and mixed ionic and electronic conductivity under conditions of technological relevance for fuel cell applications. The chemical compatibility against standard cathode materials revealed that Sr-doped LaMnO3 could be used without detectable chemical interaction up to at least 1000 degrees C. Impedance spectroscopy measurements performed in the range 400-850 degrees C, using different atmospheres (air and N-2+H-2, both dry and water vapour saturated), suggest oxygen transport numbers equal to 1 under oxidising conditions, and decreasing when exposed to extreme reducing conditions. The total conductivity at 800 degrees C increases from 1.4.10(-3) S cm(-1) in air to 2.5.10-3 S cm(-1) in wet hydrogen and 6.1.10(-3) S cm(-1) in dry hydrogen, but the observed onset of n-type conductivity has little practical impact under typical fuel cell operating conditions. (C) 2016 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE SA
issn	0925-8388
isbn	1873-4669
year published	2017
volume	697
beginning page	392
ending page	400
digital object identifier (doi)	10.1016/j.jallcom.2016.12.111
web of science category	Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering
subject category	Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
unique article identifier	WOS:000391820800051