A {sup 57}Fe Moessbauer study of REBa{sub 2}Fe{sub 3}O{sub 8+w} triple perovskites with varied oxygen content (RE = Dy, Er, and Y)

Journal Article · Sat Aug 01 04:00:00 EDT 1998 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1998.7828· OSTI ID:653140

Linden, J ^[1]; Kjekshus, A; Karen, P ^[2]; Miettinen, J; Karppinen, M ^[3]

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1. Aabo Akademi, Turku (Finland). Dept. of Physics
2. Univ. of Oslo (Norway). Dept. of Chemistry
3. Helsinki Univ. of Technology, Espoo (Finland)

REBa{sub 2}Fe{sub 3}O{sub 8+w} phases (RE = Dy, Er, and Y) with a varied oxygen content ({minus} 0.25 < w < 0.10 in general, widest for RE = Dy, narrowest for RE = Er) have been obtained by quenching from controlled atmospheres. The triple-perovskite-type structure is adopted for these phases, with two crystallographically different iron atoms, tetragonal above w {approx} {minus}0.15 and orthorhombic below that oxygen content. The valence and spin states of iron are investigated using {sup 57}Fe Moessbauer spectroscopy. At room temperature, an antiferromagnetic ordering is observed for all values of w. Six- and five-coordinated Fe{sup 3+}, S = 5/2 environments are distinguished in the Moessbauer spectra and their occupancies for w = 0 are in the exact structural ratio of these two coordinations. For w > 0, tetravalent iron (S = 2) accompanies the extra oxygen atoms at the (originally) square-pyramidal Fe site, whereas divalent iron (S = 2) accompanies the oxygen vacancies formed in the octahedral Fe site when w < 0. The latter splits into two components, the intensities of which correspond to the fractions of five- and four-coordinated iron with a random distribution of meridial oxygen vacancies in an octahedron.

• OSTI ID: 653140
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 139; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
IRON OXIDES
LATTICE PARAMETERS
OXIDES
RARE EARTH COMPOUNDS
SPECTROSCOPY
STOICHIOMETRY
X-RAY DIFFRACTION