Structural transformations of the La2−xPrxNiO4+δ system probed by high-resolution synchrotron and neutron powder diffraction. Issue 1 (5th December 2018)

• Record Type: Journal Article
• Authors: Vibhu, Vaibhav; Suchomel, Matthew R.; Penin, Nicolas; Weill, François; Grenier, Jean-Claude; Bassat, Jean-Marc; Rougier, Aline
• Is Part Of: Dalton transactions. Volume 48:Issue 1(2018)
• Page Start: 266
• Page End: 277
• Publication Date: 2018-12-05
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt03524e
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Subtle structural distortions in the La2− x Pr x NiO4+ δ system are investigated using high resolution X-ray powder diffraction and neutron powder diffraction, analyzed by combined Rietveld refinements. Abstract : Compositions in the La2− x Pr x NiO4+ δ series offer an attractive balance of chemical stability and electrochemical performance for use as cathode materials in solid oxide fuel cells (SOFCs). A detailed crystallographic study of this system has been performed, combining both high resolution synchrotron and neutron powder diffraction data, in order to investigate structural details of the series as a function of composition, temperature and oxygen over-stoichiometry. The monoclinic structure (space group F 2/ m ) of ambient temperature Pr-rich compositions for 1.0 < x ≤ 2.0 is discussed in terms of octahedra tilt arrangements and possible long-range structural modulations. In situ synchrotron diffraction experiments and TEM are employed to examine the role of temperature and interstitial oxygen on these structural distortions. With increasing La substitution, a region of mixed monoclinic and tetragonal phases is described for 0.5 ≤ x ≤ 1.0. La-Rich compositions are found to be single phase tetragonal ( F 4/ mmm for 0 < x < 0.5) or orthorhombic ( Fmmm for x = 0). Possible origins and electrochemical property consequences of the refined structural trends are considered.