15R SrMn{sub 1{minus}x}Fe{sub x}O{sub 3{minus}{delta}} (x {approx} 0.1); A new perovskite stacking sequence

Journal Article · Mon Nov 16 04:00:00 EST 1998 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic980802j· OSTI ID:316215

Cussen, E J; Sloan, J; Vente, J F; Battle, P D ^[1]; Gibb, T C ^[2]

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1. Univ. of Oxford (United Kingdom)
2. Leeds Univ. (United Kingdom). School of Chemistry

A polycrystalline sample of a new phase in the Sr-Fe-Mn-O system has been prepared by standard solid-state techniques. Characterization at room temperature by X-ray diffraction, high-resolution electron microscopy, Moessbauer spectroscopy and neutron diffraction has led to it being described as a 15-layered, rhombohedral (15R) perovskite with a previously unobserved structure. The pseudo close-packed SrO{sub 3} layers have a (cchch){sub 3} stacking sequence such that the occupation of the interstitial 6-coordinate sites by Mn (or Fe) leads to the formation of Mn{sub 2}O{sub 9} units which are linked to each other either directly by a common vertex, or indirectly via a single, vertex-sharing MnO{sub 6} octahedron. The stoichiometry of the compound was determined to be SrMn{sub 0.915(5)}O{sub 2.979(3)}. The face-sharing sites are occupied by 0.957(3)Mn/0.043(3)Fe while the exclusively corner-linked sites show a higher Fe occupation; 0.745(4)Mn/09.255(4)Fe. A neutron diffraction experiment carried out at 3 K indicated the presence of long-range magnetic order with the Mn{sup 4+} cations aligned antiferromagnetically with an ordered moment of 2.26(3){mu}{sub B}/Mn{sup 4+}. Both the neutron and the susceptibility data are consistent with the Fe cations remaining magnetically disordered to 3 K. The latter data show T{sub N} = 220 K, and suggest that some spin frustration is present at low temperatures.

• OSTI ID: 316215
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 23 Vol. 37; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
IRON OXIDES
MAGNETIC PROPERTIES
MANGANESE OXIDES
STOICHIOMETRY
STRONTIUM OXIDES