B-site substitutions in LaNb1-xMxO(4-delta) materials in the search for potential proton conductors (M=Ga, Ge, Si, B, Ti, Zr, P, Al)
authors Brandao, AD; Gracio, J; Mather, GC; Kharton, VV; Fagg, DP
nationality International
journal JOURNAL OF SOLID STATE CHEMISTRY
author keywords Ceramic Proton conductor; Solid oxide fuel cell; LaNbO4; Scheelite; Fergusonite; Electrolyte; Solid solubility
keywords DOPED LANBO4; FUEL-CELLS; CONDUCTIVITY; TRANSPORT; STABILITY; PRESSURE; SYSTEM; CA; SR
abstract The solid solubilities of potential B-site dopants in LaNb1-xMxO4-delta, materials, M=Ga, Ge, Si, Al, B, P, Zr or Ti, have been investigated in the search for possible novel proton conductors. In general, the solubility levels of these cations were found to be very low (x <= 0.03). At the maximum value x=0.03, only compositions containing Ti, Ge, Ga and Si appeared pure at the limit of resolution of XRD. The literature phase diagram, La2O3-Nb2O5-ZrO2, has been re-analysed for compositions of low Zr-content around the composition LaNbO4. The electrical properties of phase pure Ti-doped compositions have been studied. Higher bulk and total conductivities were observed in wet than dry conditions, suggesting a significant protonic contribution to total conductivity. In wet conditions, the activation energy for bulk conductivity of LaNb0.98Ti0.02O4-delta was found to be much higher than that of an A-site, Sr-doped material, Sr0.02La0.98NbO4-delta, of similar acceptor dopant concentration. The Sr-doped composition offered higher conductivities than the Ti-doped composition up to approximately 900 degrees C. (C) 2011 Elsevier Inc. All rights reserved.
publisher ACADEMIC PRESS INC ELSEVIER SCIENCE
issn 0022-4596
year published 2011
volume 184
issue 4
beginning page 863
ending page 870
digital object identifier (doi) 10.1016/j.jssc.2011.02.012
web of science category Chemistry, Inorganic & Nuclear; Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000289597100021
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