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Title: Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system

Abstract

The phase equilibria in the ½Nd{sub 2}O{sub 3}–SrO–CoO system were systematically studied at 1373 K in air. The intermediate phases formed in the ½Nd{sub 2}O{sub 3}–SrO–CoO system at 1373 K in air are: Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.0≤x≤0.5 with orthorhombic structure, sp. gr. Pbnm and 0.6≤x≤0.95 whose structure was detected as cubic according to XRD sp. gr. Pm3m, but shown to be tetragonal by TEM due to the oxygen vacancy ordering), Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} (0.6≤y≤1.1 with tetragonal K{sub 2}NiF{sub 4}-type structure, sp. gr. I4/mmm) and Nd{sub 2-z}Sr{sub z}O{sub 3} (0.0≤z≤0.15 with hexagonal structure, sp. gr. P-3m1). The unit cell parameters for the single phase samples were refined by the Rietveld analysis. The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.6≤x≤0.95) and Ruddlesden-Popper oxide Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} were examined by TGA. All were found to be oxygen deficient phases. High-temperature dilatometry allows calculating the thermal expansion coefficient and evaluating the chemical expansion coefficient at high temperature. The projection of isothermal-isobaric phase diagram for the Nd–Sr–Co–O system at 1373 K in air to the compositional triangle of metallic components has been constructed. The phase equilibria in the studied Nd–Sr–Co–O system were compared to La–Sr–Co–O and Nd–M–Co–O (M=Ca andmore » Ba). - Graphical abstract: Crystal structure of vacancy ordered supercell for Nd{sub 0.2}Sr{sub 0.8}CoO{sub 3-δ} and projection of phase diagram for the Nd–Sr–Co–O system onto the triangle edge of metallic components at 1373 K in air. - Highlights: • The diagram for the Nd–Sr–Co–O system at 1373 K in air has been constructed. • The crystal structure of Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} was refined. • The formation of superstructure due to the oxygen vacancy ordering was proved. • The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} were examined. • Thermal expansion and chemical expansion for Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} were evaluated.« less

Authors:
;  [1];  [2]; ;  [1];  [1]
  1. Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation)
  2. Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France)
Publication Date:
OSTI Identifier:
22658252
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 248; Other Information: Copyright (c) 2017 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; COBALT OXIDES; CUBIC LATTICES; NEODYMIUM OXIDES; ORTHORHOMBIC LATTICES; OXIDATION; OXYGEN; PHASE DIAGRAMS; SOLID SOLUTIONS; STRONTIUM OXIDES; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; TETRAGONAL LATTICES; THERMAL EXPANSION; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION

Citation Formats

Aksenova, T.V., Efimova, T.G., Lebedev, O.I., Elkalashy, Sh.I., Urusova, A.S., and Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru. Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2017.02.002.
Aksenova, T.V., Efimova, T.G., Lebedev, O.I., Elkalashy, Sh.I., Urusova, A.S., & Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru. Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system. United States. doi:10.1016/J.JSSC.2017.02.002.
Aksenova, T.V., Efimova, T.G., Lebedev, O.I., Elkalashy, Sh.I., Urusova, A.S., and Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru. Sat . "Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system". United States. doi:10.1016/J.JSSC.2017.02.002.
@article{osti_22658252,
title = {Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system},
author = {Aksenova, T.V. and Efimova, T.G. and Lebedev, O.I. and Elkalashy, Sh.I. and Urusova, A.S. and Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru},
abstractNote = {The phase equilibria in the ½Nd{sub 2}O{sub 3}–SrO–CoO system were systematically studied at 1373 K in air. The intermediate phases formed in the ½Nd{sub 2}O{sub 3}–SrO–CoO system at 1373 K in air are: Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.0≤x≤0.5 with orthorhombic structure, sp. gr. Pbnm and 0.6≤x≤0.95 whose structure was detected as cubic according to XRD sp. gr. Pm3m, but shown to be tetragonal by TEM due to the oxygen vacancy ordering), Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} (0.6≤y≤1.1 with tetragonal K{sub 2}NiF{sub 4}-type structure, sp. gr. I4/mmm) and Nd{sub 2-z}Sr{sub z}O{sub 3} (0.0≤z≤0.15 with hexagonal structure, sp. gr. P-3m1). The unit cell parameters for the single phase samples were refined by the Rietveld analysis. The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.6≤x≤0.95) and Ruddlesden-Popper oxide Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} were examined by TGA. All were found to be oxygen deficient phases. High-temperature dilatometry allows calculating the thermal expansion coefficient and evaluating the chemical expansion coefficient at high temperature. The projection of isothermal-isobaric phase diagram for the Nd–Sr–Co–O system at 1373 K in air to the compositional triangle of metallic components has been constructed. The phase equilibria in the studied Nd–Sr–Co–O system were compared to La–Sr–Co–O and Nd–M–Co–O (M=Ca and Ba). - Graphical abstract: Crystal structure of vacancy ordered supercell for Nd{sub 0.2}Sr{sub 0.8}CoO{sub 3-δ} and projection of phase diagram for the Nd–Sr–Co–O system onto the triangle edge of metallic components at 1373 K in air. - Highlights: • The diagram for the Nd–Sr–Co–O system at 1373 K in air has been constructed. • The crystal structure of Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} was refined. • The formation of superstructure due to the oxygen vacancy ordering was proved. • The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} were examined. • Thermal expansion and chemical expansion for Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} were evaluated.},
doi = {10.1016/J.JSSC.2017.02.002},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 248,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2017},
month = {Sat Apr 15 00:00:00 EDT 2017}
}
  • Data are presented on the phase equilibria and crystal chemistry of the ternary system SrO-CaO-[1/2]Bi[sub 2]O[sub 3]. Symmetry data and unit-cell dimensions based on single-crystal and powder X-ray diffraction measurements are reported for the two monoclinic phases. The monoclinic phase with a Sr:Ca:Bi ratio of 99:33:68 was shown to have both high- and low-temperature (black) oxidized forms.
  • The phase diagram of the CaO–1/2 Nd{sub 2}O{sub 3}–CoO{sub z} system at 885 °C in air has been determined. The system consists of two calcium cobaltate compounds that have promising thermoelectric properties, namely, the 2D thermoelectric oxide solid solution, (Ca{sub 3−x}Nd{sub x})Co{sub 4}O{sub 9−z} (0≤x≤0.5), which has a misfit layered structure, and Ca{sub 3}Co{sub 2}O{sub 6} which consists of 1D chains of alternating CoO{sub 6} trigonal prisms and CoO{sub 6} octahedra. Ca{sub 3}Co{sub 2}O{sub 6} was found to be a point compound without the substitution of Nd on the Ca site. The reported Nd{sub 2}CoO{sub 4} phase was not observedmore » at 885 °C. A ternary (Ca{sub 1−x}Nd{sub 1+x})CoO{sub 4−z} (x=0) phase, or (CaNdCo)O{sub 4−z}, was found to be stable at this temperature. A solid solution region of distorted perovskite (Nd{sub 1−x}Ca{sub x})CoO{sub 3−z} (0≤x≤0.25, space group Pnma) was established. In the peripheral binary systems, while a solid solution region was identified for (Nd{sub 1−x}Ca{sub x}){sub 2}O{sub 3−z} (0≤x≤0.2), Nd was not found to substitute in the Ca site of CaO. Six solid solution tie-line regions and six three-phase regions were determined in the CaO–Nd{sub 2}O{sub 3}–CoO{sub z} system in air. - Graphical abstract: Phase diagram of the 1/2 Nd{sub 2}O{sub 3}–CaO–CoO{sub x} system at 885 °C, showing the limits of various solid solutions, and the tie-line relationships of various phases. - Highlights: • Phase diagram of the CaO–1/2 Nd{sub 2}O{sub 3}–CoO{sub z} system constructed. • System consists of thermoelectric oxide (Ca{sub 3−x}Nd{sub x})Co{sub 4}O{sub 9−z} (0≤x≤0.5). • Structures of (Nd{sub 1−x}Ca{sub x})CoO{sub 3−z} and (CaNdCo)O{sub 4−z} determined.« less
  • New data are presented on the phase equilibria and crystal chemistry of the binary systems CaO-Bi[sub 2]O[sub 3] and CaO-CuO and the ternary CaO-Bi[sub 2]O[sub 3]-CuO. Symmetry data and unit cell dimensions based on single crystal and powder x-ray diffraction measurements are reported for several of the binary CaO-Bi[sub 2]O[sub 3] phases, including corrected compositions for Ca[sub 4]Bi[sub 6]O[sub 13] and Ca[sub 2]Bi[sub 2]O[sub 5]. The ternary system contains no new ternary phases which can be formed in air at [approximately]700--900 C.
  • A partial study of the solid-solid equilibria in the quaternary system BaO-SrO-CaO-CuO has been undertaken in order to determine the observed phases and their evolution when Ba is substituted for Sr in mixtures (Sr/Ba){sub 2}CaCu{sub 2}O{sub x} and (Sr/Ba){sub 2}Ca{sub 2}Cu{sub 3}O{sub x}. The temperature was fixed at 950 C and samples were elaborated under 1 bar of flowing oxygen. It has been shown that two four-phased domains exist in this quaternary system, including the following phases: ({und Ba}/Sr/Ca)CuO{sub 2}, ({und Sr/Ca}/Ba){sub 2}CuO{sub 3}, ({und Sr/Ca}/Ba){sub 14}Cu{sub 24}O{sub x}, and Ba{sub 4}CaCu{sub 3}O{sub 8} substituted Sr/Ca for the one andmore » ({und Ba}/Sr/Ca)CuO{sub 2}, ({und Sr/Ca}/Ba){sub 2}CuO{sub 3}, ({und Sr/Ca}/Ba){sub 14}Cu{sub 24}O{sub x}, and ({und Sr/Ca}/Ba/)CuO{sub 2} for the other.« less
  • Phase equilibria, crystal structure, and transport properties in the (100-x) La{sub 0.95}Ni{sub 0.6}Fe{sub 0.4}O{sub 3}-xCeO{sub 2} (LNFCx) system (x=2-75 mol%) were studied in air. Evolution of phase compositions and crystal structure of components was observed. The LNFCx (2{<=}x{<=}10) are three-phase and comprise the perovskite phase with rhombohedral symmetry (R3-bar c), the modified ceria with fluorite structure (Fm3-bar m), and NiO as a secondary phase. These multiphase compositions exhibit metallic-like conductivity above 300 deg. C. Their conductivity gradually decreases from 395.6 to 260.6 S/cm, whereas the activation energy remains the same (E{sub a}=0.04-0.05 eV), implying the decrease in the concentration ofmore » charge carriers. Phase compositions in the LNFCx (25{<=}x{<=}75) are more complicated. A change from semiconducting to metallic-like conductivity behavior was observed in LNFC25 at about 550 deg. C. The conductivity of LNFCx (25{<=}x{<=}75) could be explained in terms of a modified simple mixture model. - Graphical abstract: Diverse phase compositions and evolution of the crystal structure of components were observed in the (100-x) La{sub 0.95}Ni{sub 0.6}Fe{sub 0.4}O{sub 3}-xCeO{sub 2} (LNFCx) system fabricated under oxidizing atmosphere. The presence of secondary phase(s) influences conductivity behavior in this system. A modified simple mixture model could explain conductivity of the LNFCx (25{<=}x{<=}75) compositions. Highlights: > Evolution of phase compositions and crystal structure of components was observed. > The presence of secondary phase(s) influences conductivity behavior in this system. > A modified simple mixture model can explain conductivity of the LNFCx (25{<=}x{<=}75). > La dissolution in CeO{sub 2} exceeds possible dopant concentration in Ce{sub 1-x}Ln{sub x}O{sub 2-{delta}} electrolyte.« less