Hyperfine interactions and local environment of {sup 57}Fe probe atoms in perovskite CaMn{sub 7}O{sub 12}

Journal Article · Sat Dec 01 00:00:00 EST 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.214407· OSTI ID:21052805

Presniakov, I A; Rusakov, V S; Gubaidulina, T V; Sobolev, A V; Goodilin, E A; Knot'ko, A V ^[1]; Baranov, A V ^[1]; Demazeau, G ^[2]; Volkova, O S ^[1]; Cherepanov, V M ^[3]; Isobe, M ^[4]

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1. Lomonosov Moscow State University, Leninskie Gory, Moscow 119992 (Russian Federation)
2. ICMCB, CNRS, University Bordeaux 1, site of ENSCPB, 87 Avenue du Dr A. Schweitzer, 33608 Pessac Cedex (France)
3. Russian Research Centre Kurchatov Institute, Moscow 123182 (Russian Federation)
4. Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa, Chiba 277-8581 (Japan)

Moessbauer spectroscopy has been applied for studying the local environment of {sup 57}Fe probe atoms within iron-doped CaMn{sub 7}O{sub 12} manganite with a perovskite-like structure. The {sup 57}Fe spectra recorded in the paramagnetic temperature range 90 K<T<380 K, where CaMn{sub 7}O{sub 12} has a rhombohedral structure (R3), were discussed supposing Fe{sup 3+} probe cations to replace manganese in the octahedral (Mn{sup 3+}O{sub 6}) and (Mn{sup 4+}O{sub 6}) polyhedra. A very small (<3%) part of Fe{sup 3+} probe cations characterized by very large quadrupole splitting ({approx}2 mm/s) suggests that a few amounts of {sup 57}Fe probe can be substituted for Mn{sup 3+} in the (9e) positions with approximately a square planar surrounding. In the temperature range 380 K<T<450 K, the {sup 57}Fe Moessbauer spectra undergo a sharp change which can be due to a formation (at T{sub CO}{approx}380 K) and a gradual growth with temperature of the cubic manganite phase (Im3). At T{>=}450 K, the {sup 57}Fe spectrum reveals single Fe{sup 3+} sites in an oxygen symmetric octahedral surrounding. This can be well explained by a fast electron exchange Mn{sup 3+}{r_reversible}Mn{sup 4+}, leading to the crystallographic equivalence of all MnO{sub 6} positions. At the temperature range T<T{sub M2} (=90 K), an appearance of the distributions of the hyperfine magnetic field values at the {sup 57}Fe nucleus up to {approx}350 kOe (at 77.4 K) was observed. This result is an independent experimental evidence of magnetic ordering in the manganese sublattice.

• OSTI ID: 21052805
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 21; Other Information: DOI: 10.1103/PhysRevB.76.214407; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM COMPOUNDS
CATIONS
CRYSTALLOGRAPHY
CUBIC LATTICES
DOPED MATERIALS
ELECTRON EXCHANGE
ELECTRONS
EXCHANGE INTERACTIONS
IRON
IRON 57
IRON IONS
MAGNETIC FIELDS
MANGANESE
MANGANESE IONS
MOESSBAUER EFFECT
PARAMAGNETISM
PEROVSKITE
QUADRUPOLES
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K