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

Journal Article · Mon Sep 15 00:00:00 EDT 2014 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.05.017· OSTI ID:22443395

Dabrowski, B. ^[1]; Avdeev, M. ^[2]; Kolesnik, S.; Remsen, S. ^[1]; Chmaissem, O. ^[1]

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1. Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States)
2. Australian Nuclear Science and Technology Organization, ANSTO, Sydney, NSW (Australia)

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 the 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.

• OSTI ID: 22443395
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 217; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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