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


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.




Chemistry; Materials Science; Metallurgy & Metallurgical Engineering


Canu, G; Buscaglia, V; Ferrara, C; Mustarelli, P; Patricio, SG; Rondao, AIB; Tealdi, C; Marques, FMB

nossos autores


The Authors acknowledge Prof. Adelina Ianculescu (Polytechnic University of Bucharest, Romania) for HR-TEM analysis and Mr. Edoardo Delponte (University of Pavia, Italy) for his contribution to the compatibility tests. This work was performed within the framework of the Italian National MIUR Project FIRB2012 "INCYPIT", RBFR12CQP5. Funding from Project CICECO-Aveiro Institute of Materials POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013), financed by national funds through FCT/MEC (Portugal) and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement is greatly appreciated. S. Patricio and A. Rondcao also thank FCT for their grants (SFRH/BPD/75943/2011 and SFRH/BDE/52139/2013). The companies H.C. Starck and Treibacher Industrie AG are acknowledged for providing the raw materials.

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