Synthesis and characterization of Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}M{sub x}O{sub 2.625+{delta}} (M=Ga, 0.125=<x=<0.500 and M=Fe, 0.125=<x=<0.875)

Journal Article · Mon May 15 00:00:00 EDT 2006 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.01.057· OSTI ID:20785008

Lindberg, F ^[1]; Drozhzhin, O A ^[2]; Istomin, S Ya ^[3]; Svensson, G ^[1]; Kaynak, F B ^[4]; Svedlindh, P ^[5]; Warnicke, P ^[5]; Wannberg, A ^[6]; Mellergard, A ^[6]; Antipov, E V ^[3]

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1. Department of Structural Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden)
2. Department of Materials Science, Moscow State University, 119992 Moscow (Russian Federation)
3. Department of Chemistry, Moscow State University, 119992 Moscow (Russian Federation)
4. Department of Physics Engineering, Faculty of Engineering, Hacettepe University, 06800, Ankara (Turkey)
5. Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21, Uppsala (Sweden)
6. Studsvik Neutron Research Laboratory, Uppsala University, SE-611 82 Nykoeping Sweden (Sweden)

The effect of replacing Co{sup 3+} by Ga{sup 3+} and Fe{sup 3+} in the perovskite-related tetragonal phase Sr{sub 0.75}Y{sub 0.25}CoO{sub 2.625} with unit cell parameters: a=2a{sub p}, and c=4a{sub p} (314 phase) has been investigated. The 314 phase is formed by Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}M{sub x}O{sub 2.625+{delta}}, with x=<0.375 for M=Ga and x=<0.625 for M=Fe. High-resolution transmission electron microscopy and electron diffraction revealed frequent microtwinning in the iron-containing compounds, in contrast to the Ga-substituted 314 phases. Diffraction experiments and electron microscope images indicated that at higher Fe contents, 0.75=<x=<0.875, a disordered cubic perovskite structure forms. The crystal structures of Sr{sub 0.75}Y{sub 0.25}Co{sub 0.75}Ga{sub 0.25}O{sub 2.625} and Sr{sub 0.75}Y{sub 0.25}Co{sub 0.5}Fe{sub 0.5}O{sub 2.625+{delta}} were refined using neutron powder diffraction data. It was found that the oxygen content of Sr{sub 0.75}Y{sub 0.25}Co{sub 0.5}Fe{sub 0.5}O{sub 2.625+{delta}} is higher than in Fe-free 314 phase, so that {delta} corresponds to 0.076, whereas {delta}=0 in Sr{sub 0.75}Y{sub 0.25}Co{sub 0.75}Ga{sub 0.25}O{sub 2.625+{delta}}. Magnetization measurements on the unsubstituted Sr{sub 0.7}Y{sub 0.3}CoO{sub 2.62} and Ga-substituted Sr{sub 0.75}Y{sub 0.25}Co{sub 0.75}Ga{sub 0.25}O{sub 2.625} compounds indicate the presence of a ferromagnetic-like contribution to the measured magnetization at 320 and 225K, respectively, while replacing Co by Fe leads to the suppression of this contribution. A neutron diffraction study shows that the Sr{sub 0.75}Y{sub 0.25}Co{sub 0.5}Fe{sub 0.5}O{sub 2.625+{delta}} compound is G-type antiferromagnetic at room temperature, whereas Sr{sub 0.75}Y{sub 0.25}Co{sub 0.75}Ga{sub 0.25}O{sub 2.625} does not exhibit magnetic ordering at room temperature.

• OSTI ID: 20785008
• Journal Information: Journal of Solid State Chemistry, Vol. 179, Issue 5; Other Information: DOI: 10.1016/j.jssc.2006.01.057; PII: S0022-4596(06)00071-5; Copyright (c) 2006 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
ANTIFERROMAGNETISM
COBALT COMPOUNDS
COBALT IONS
CRYSTAL STRUCTURE
ELECTRON DIFFRACTION
ELECTRON MICROSCOPES
GALLIUM COMPOUNDS
GALLIUM IONS
IRON COMPOUNDS
IRON IONS
MAGNETIZATION
NEUTRON DIFFRACTION
PEROVSKITE
STRONTIUM COMPOUNDS
SYNTHESIS
TEMPERATURE RANGE 0273-0400 K
TRANSMISSION ELECTRON MICROSCOPY
YTTRIUM COMPOUNDS