Magnetic structure of Sr{sub 2}Fe{sub 2}O{sub 5} brownmillerite by single-crystal Mössbauer spectroscopy

Journal Article · Sun Sep 15 00:00:00 EDT 2013 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2013.06.030· OSTI ID:22274063

Waerenborgh, J. C. ^[1]; Tsipis, E. V. ^[1]; Auckett, J. E.; Ling, C. D. ^[2]

---

1. UCQR, IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, CFMC-UL, Estrada Nacional 10, 2686-953 Sacavém (Portugal)
2. School of Chemistry, The University of Sydney, Sydney 2006 (Australia)

In order to determine orientation of the Fe{sup 3+} magnetic moments and electric field gradient (efg) axes in the brownmillerite-type strontium ferrite structure for both iron sublattices where the efg tensor is not axially symmetric, the Mössbauer spectra of powdered and oriented single-crystal Sr{sub 2}Fe{sub 2}O{sub 5} were analyzed by solving the complete Hamiltonian for hyperfine interactions in the excited and ground states of the {sup 57}Fe nuclei. The magnetic moments of both octahedrally and tetrahedrally coordinated iron cations lie on the ac-plane of the orthorhombic unit cell and are parallel to the shortest c-axis, whilst the main efg axes are parallel to the longest crystallographic axis, b. This orientation is similar to that in Ca{sub 2}Fe{sub 2}O{sub 5}, in spite of the structural differences of strontium and calcium ferrite brownmillerites at low temperatures. - Graphical abstract: Mössbauer spectra of powdered and oriented single-crystal Sr{sub 2}Fe{sub 2}O{sub 5}, analyzed by solving the complete Hamiltonian for hyperfine interactions in the excited and ground states of the {sup 57}Fe nuclei, show that the magnetic moments of both octahedrally and tetrahedrally coordinated iron cations are parallel to the shortest c-axis of the orthorhombic brownmillerite unit cell . Display Omitted - Highlights: • Single-crystal Mössbauer spectroscopy is used to study magnetic structure of Sr{sub 2}Fe{sub 2}O{sub 5}. • Complete Hamiltonian for hyperfine interactions in excited and ground states was solved. • Fe{sup 3+} magnetic moments are parallel to the shortest crystallographic axis c. • The orientation of nuclear electric field gradient is similar to that in Ca{sub 2}Fe{sub 2}O{sub 5}.

• OSTI ID: 22274063
• Journal Information: Journal of Solid State Chemistry, Vol. 205; Other Information: Copyright (c) 2013 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
36 MATERIALS SCIENCE
CALCIUM
CATIONS
CRYSTALLOGRAPHY
ELECTRIC FIELDS
FERRITE
FERRITES
GROUND STATES
HAMILTONIANS
INTERACTIONS
IRON
IRON 57
IRON IONS
MAGNETIC MOMENTS
MONOCRYSTALS
ORIENTATION
ORTHORHOMBIC LATTICES
POWDERS
SPECTRA
SPECTROSCOPY
STRONTIUM