High-temperature characterization of oxygen-deficient K2NiF4-type Nd2-xSrxNiO4-delta O4-delta (x=1.0-1.6) for potential SOFC/SOEC applications
authors Kravchenko, E; Khalyavin, D; Zakharchuk, K; Grins, J; Svensson, G; Pankov, V; Yaremchenko, A
nationality International
journal JOURNAL OF MATERIALS CHEMISTRY A
keywords OXIDE FUEL-CELLS; NEGATIVE THERMAL-EXPANSION; TRANSPORT-PROPERTIES; CRYSTAL-STRUCTURE; ELECTROCHEMICAL PROPERTIES; MAGNETIC-PROPERTIES; STRUCTURAL-CHANGES; PARTIAL-PRESSURE; ND2-XSRXNIO4+DELTA; NICKELATE
abstract Previously unexplored oxygen-deficient RuddLesden-Popper Nd2-xSrxNiO4-delta (x = 1.0-1.6) nickelates were evaluated for potential use as oxygen electrode materials for solid oxide fuel and electrolysis ceRs, with emphasis on structural stability, oxygen nonstoichiometry, dimensional changes, and electrical properties. Nd2-xSrxNiO4-delta ceramics possess the K2NiF4-type tetragonal structure under oxidizing conditions at 25-1000 degrees C. Acceptor-type substitution by strontium is compensated by the generation of eLectron-hoLes and oxygen vacancies. Oxygen deficiency increases with temperature and strontium doping reaching -1/8 of oxygen sites for x = 1.6 at 1000 degrees C in air. Strongly anisotropic expansion of the tetragonal Lattice on heating correlated with oxygen nonstoichiometry changes results in an anomalous dilatometric behavior of Nd2-xSrxNiO4-delta ceramics under oxidizing conditions. Moderate thermal expansion coefficients, (11-14) x 10(-6) K-1, ensure however thermomechanical compatibility with common solid electrolytes. Reduction in inert atmosphere induces oxygen vacancy ordering accompanied by a contraction of the Lattice and a decrease of its symmetry to orthorhombic. Nd2-xSrxNiO4-delta ceramics exhibit a p-type metallic-Like electrical conductivity at 500-1000 degrees C under oxidizing conditions, with the highest conductivity (290 S cm(-1) at 900 degrees C in air) observed for x = 1.2. The high Lev& of oxygen deficiency in Sr-rich Nd2-xSrxNiO4 impLies enhanced mixed ionic-electronic transport favorable for electrode applications.
publisher ROYAL SOC CHEMISTRY
issn 2050-7488
year published 2015
volume 3
issue 47
beginning page 23852
ending page 23863
digital object identifier (doi) 10.1039/c5ta06779k
web of science category Chemistry, Physical; Energy & Fuels; Materials Science, Multidisciplinary
subject category Chemistry; Energy & Fuels; Materials Science
unique article identifier WOS:000365205000026
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