Thermochemical behavior and transport properties of Pr-substituted SrTiO3 as potential solid oxide fuel cell anode

authors	Yaremchenko, AA; Patricio, SG; Frade, JR
nationality	International
journal	JOURNAL OF POWER SOURCES
author keywords	Strontium titanate; SOFC anode; Electrical conductivity; Thermal expansion; Chemical expansion; Stability
keywords	NB-DOPED SRTIO3; STRONTIUM-TITANATE; LOW-TEMPERATURES; SOFC ANODES; PRASEODYMIUM; DIFFUSION; CERAMICS; SYSTEM; DEFECT; GAS
abstract	Phase composition, structural stability, electrical properties, thermochemical expansion and redox behavior of Pr-substituted SrTiO3 were assessed for potential application in solid oxide fuel cell anodes. XRD analysis confirms formation of single-phase perovskite-like Sr1-xPrxTiO3 +/-delta and Sr1-1.5xPrxTiO3 +/-delta (x = 0.02-0.30) ceramics under both oxidizing and reducing conditions, although microstructural studies indicate minor precipitation of TiO2 in reduced Sr-deficient ceramics with high Pr content. XPS analysis in combination with XRD suggests that Pr cations substitute into strontium sublattice in mixed 4+/3+ oxidation state and are essentially insoluble in titanium sublattice. Reduction at elevated temperatures results in 2-3 orders of magnitude increase of n-type electronic conductivity with respect to oxidized materials. Thermogravimetric and electrical studies demonstrate however very slow reduction kinetics at temperatures below 1273 K associated with nearly frozen equilibrium in cation sublattice and low oxygen vacancy concentration in oxidized materials. Electrical behavior is discussed in conjunction with defect chemistry of donor-doped strontium titanate. All oxidized and reduced materials exhibit moderate thermal expansion coefficients, compatible with that of common solid electrolytes, and a small contribution of chemical expansion on reduction. (C) 2013 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	0378-7753
year published	2014
volume	245
beginning page	557
ending page	569
digital object identifier (doi)	10.1016/j.jpowsour.2013.07.019
web of science category	Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary
subject category	Chemistry; Electrochemistry; Energy & Fuels; Materials Science
unique article identifier	WOS:000325234500071