High-temperature characterization of oxygen-eficient K2NiF4-type Nd2-xSrxNiO4-delta O4-delta (x=1.0-1.6) for potential SOFC/SOEC applications
Number of Authors: 7
2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 47, 23852-23863 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2015. Vol. 3, no 47, 23852-23863 p.
Chemical Sciences Environmental Engineering Materials Engineering
IdentifiersURN: urn:nbn:se:su:diva-125490DOI: 10.1039/c5ta06779kISI: 000365205000026OAI: oai:DiVA.org:su-125490DiVA: diva2:893682