Orthorhombic superstructures within the rare earth strontium-doped cobaltate perovskites: Ln{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (Ln=Y{sup 3+}, Dy{sup 3+}-Yb{sup 3+}; 0.750{<=}x{<=}0.875)

Journal Article · Wed Aug 15 00:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.04.029· OSTI ID:21043799

James, Michael ^[1]; Avdeev, Maxim ^[1]; Barnes, Paris ^[2]; Morales, Liliana ^[1]; Wallwork, Kia ^[3]; Withers, Ray ^[4]

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1. Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234 (Australia)
2. Materials Science Division, MSD 223, Argonne National Laboratory, Argonne, IL 60439 (United States)
3. Australian Synchrotron, 800 Blackburn Road, Clayton, Vict. 3168 (Australia)
4. Research School of Chemistry, Australian National University, Canberra 0200, ACT (Australia)

A combination of electron, synchrotron X-ray and neutron powder diffraction reveals a new orthorhombic structure type within the Sr-doped rare earth perovskite cobaltates Ln{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (Ln=Y{sup 3+}, Dy{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+}and Yb{sup 3+}). Electron diffraction shows a C-centred cell based on a 2{radical}2a{sub p}x4a{sub p}x4{radical}2a{sub p} superstructure of the basic perovskite unit. Not all of these very weak satellite reflections are evident in the synchrotron X-ray and neutron powder diffraction data and the average structure of each member of this series could only be refined based on Cmma symmetry and a 2{radical}2a{sub p}x4a{sub p}x2{radical}2a{sub p} cell. The nature of structural and magnetic ordering in these phases relies on both oxygen vacancy and cation distribution. A small range of solid solution exists where this orthorhombic structure type is observed, centred roughly around the compositions Ln{sub 0.2}Sr{sub 0.8}CoO{sub 3-{delta}}. In the case of Yb{sup 3+} the pure orthorhombic phase was only observed for 0.850{<=}x{<=}0.875. Tetragonal (I4/mmm; 2a{sub p}x2a{sub p}x4a{sub p}) superstructures were observed for compositions having higher or lower Sr-doping levels, or for compounds with rare earth ions larger than Dy{sup 3+}. These orthorhombic phases show mixed valence (3+/4+) cobalt oxidation states between 3.2+ and 3.3+. DC magnetic susceptibility measurements show an additional magnetic transition for these orthorhombic phases compared to the associated tetragonal compounds with critical temperatures > 330 K. - Graphical abstract: A study using electron, high-resolution synchrotron X-ray and neutron powder diffraction reveals a new family of orthorhombic perovskite superstructures (Ln{sub 0.2}Sr{sub 0.8}CoO{sub 3-{delta}}), that shows A-site (Ln{sup 3+}/Sr{sup 2+}) cation ordering as well as oxygen vacancy ordering.

• OSTI ID: 21043799
• Journal Information: Journal of Solid State Chemistry, Vol. 180, Issue 8; Other Information: DOI: 10.1016/j.jssc.2007.04.029; PII: S0022-4596(07)00155-7; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT COMPOUNDS
DOPED MATERIALS
DYSPROSIUM COMPOUNDS
DYSPROSIUM IONS
ERBIUM IONS
HOLMIUM COMPOUNDS
HOLMIUM IONS
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
OXIDES
PEROVSKITE
STRONTIUM COMPOUNDS
STRONTIUM IONS
TETRAGONAL LATTICES
THULIUM COMPOUNDS
THULIUM IONS
YTTERBIUM COMPOUNDS
YTTERBIUM IONS
YTTRIUM COMPOUNDS
YTTRIUM IONS