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Title: Structural, magnetic, and oxygen storage properties of hexagonal Dy{sub 1−x}Y{sub x}MnO{sub 3+δ}

Single-phase polycrystalline samples of hexagonal Dy{sub 1−x}Y{sub x}MnO{sub 3+δ} were synthesized over the full solubility range under reducing oxygen partial pressure conditions. Rietveld refinements using neutron powder diffraction data (NPD) confirmed the persistence of the parent hexagonal P6{sub 3}cm (Space group #185) structure for all the stoichiometric (δ=0) samples. The (Mn–O) bond lengths derived from NPD data were found to be consistent with non-degenerate Mn{sup +3} high-spin state e“{sup 2}e′{sup 2} in trigonal–bipyramidal coordination. Detailed thermogravimetric measurements show large reversible oxygen storage/release capabilities (within the range of oxygen content 3.0–3.3) at unusually low temperatures of 200–400 °C in air or oxygen atmospheres. A phase transition to a new hexagonal phase (Hex1) was observed to take place around δ∼0.29 for the oxygen-loaded Dy-rich samples (x<0.5). Analysis of x-ray and neutron diffraction data using Rietveld refinements demonstrate that the superstructure is formed by tripling the c-axis of the original P6{sub 3}cm unit cell. Modeling of the Hex1 superstructure converged to a structural symmetry consistent with the noncentrosymmetric space group R3c (#161). In magnetization measurements, a ferrimagnetic order for DyMnO{sub 3.0} was observed below 8 K. The dilution of Dy magnetism with nonmagnetic yttrium results in reducing both the transition temperature and themore » effective paramagnetic moment. - Graphical abstract: Superstructure of the (R3c) Dy{sub 0.7}Y{sub 0.3}MnO{sub 3.29} in the lattice range c=0.27611–0.42829 (left panel) along with its low-temperature oxygen absorption/desorption capability in pure O{sub 2} (right panel). - Highlights: • Polycrystalline samples of Dy{sub 1−x}Y{sub x}MnO{sub 3+δ} were synthesized in the hexagonal phase. • They exhibit large oxygen storage/release capabilities at low oxidation temperatures. • A phase transition to the R3c superstructure was observed around δ=0.29. • Both the Tc and effective paramagnetic moment were reduced with the Dy substitution.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ; ;  [1] ;  [1] ;  [2]
  1. Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States)
  2. (United States)
  3. Australian Nuclear Science and Technology Organization, ANSTO, Sydney, NSW (Australia)
Publication Date:
OSTI Identifier:
22443395
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 217; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; ABSORPTION; BOND LENGTHS; DESORPTION; HEXAGONAL LATTICES; HIGH SPIN STATES; MAGNETIC PROPERTIES; MAGNETIZATION; NEUTRON DIFFRACTION; OXIDATION; OXYGEN; PARAMAGNETISM; PARTIAL PRESSURE; PHASE TRANSFORMATIONS; POLYCRYSTALS; SPACE GROUPS; THERMAL GRAVIMETRIC ANALYSIS; TRANSITION TEMPERATURE; TRIGONAL LATTICES; X-RAY DIFFRACTION; YTTRIUM