Crystal structure and magnetic properties of high-oxygen pressure annealed Sr{sub 1-x}La{sub x}Co{sub 0.5}Fe{sub 0.5}O{sub 3-{delta}} (0{<=}x{<=}0.5)

Journal Article · Sun Feb 15 04:00:00 EST 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.10.030· OSTI ID:21212190

Swierczek, Konrad ^[1]; Dabrowski, Bogdan ^[1]; Suescun, Leopoldo ^[2]; Kolesnik, Stanislaw ^[1]

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1. Physics Department, Northern Illinois University, DeKalb, IL 60115 (United States)
2. Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

Structural and magnetic studies are presented for the perovskite type Sr{sub 1-x}La{sub x}Co{sub 0.5}Fe{sub 0.5}O{sub 3-{delta}} (0{<=}x{<=}0.5) materials annealed under moderately high-oxygen pressures of {approx}200 atm. A detailed analysis of the room temperature neutron time-of-flight diffraction data reveals that the crystal structure of the sample SrCo{sub 0.5}Fe{sub 0.5}O{sub 2.89(1)}, previously described as vacancy-disordered cubic, is similar to the formerly reported, oxygen-vacancy ordered Sr{sub 8}Fe{sub 8}O{sub 23} compound, i.e. Sr{sub 8}Co{sub 4}Fe{sub 4}O{sub 23} is tetragonal with the I4/mmm symmetry. With an increase of the La content the studied materials become nearly oxygen stoichiometric and a lowering of the crystal symmetry is observed from cubic Pm3-barm (x=0.1 and 0.2) to tetragonal I4/mcm (x=0.3 and 0.4), and finally to monoclinic I12/c1 (x=0.5). Low-temperature structural and magnetic measurements show a ferromagnetic ordering with the maximum Curie temperature near 290 K at x=0.2. - Graphical Abstract: Room temperature Rietveld refinement profile using I4/mmm space group for the oxygen vacancy ordered SrCo{sub 0.5}Fe{sub 0.5}O{sub 2.89} (Sr{sub 8}Co{sub 4}Fe{sub 4}O{sub 23}). Top tick-marks denote allowed reflections in I4/mmm, bottom one emphasize the possibility of inexact indexing using Pm3-barm symmetry. Previous reports indicate that similar ordering is common for SrCo{sub 1-x}Fe{sub x}O{sub 3-{delta}} compounds possibly hindering their applications.

• OSTI ID: 21212190
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 182; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANNEALING
COBALT COMPOUNDS
CRYSTALS
CURIE POINT
FERROMAGNETISM
IRON COMPOUNDS
LANTHANUM COMPOUNDS
MAGNETIC PROPERTIES
MONOCLINIC LATTICES
NEUTRON DIFFRACTION
OXIDES
OXYGEN
PEROVSKITE
PHASE TRANSFORMATIONS
SPACE GROUPS
STRONTIUM COMPOUNDS
TEMPERATURE RANGE 0273-0400 K
TETRAGONAL LATTICES
TIME-OF-FLIGHT METHOD
VACANCIES