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Fluorination of perovskite-related phases of composition SrFe1-xSnxO3-delta

Berry, Frank J.; Bowfield, Andrew F.; Coomer, Fiona C.; Jackson, Simon D.; Moore, Elaine A.; Slater, Peter R.; Thomas, Michael F.; Wrtght, Adrian J. and Ren, Xiaolin (2009). Fluorination of perovskite-related phases of composition SrFe1-xSnxO3-delta. Journal of Physics: Condensed Matter, 21(25) p. 256001.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1088/0953-8984/21/25/256001
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Abstract

Perovskite-related compounds of composition SrFe1−xSnxO3−δ (x = 0.31, 0.54) have been prepared. X-ray powder diffraction shows that the materials adopt orthorhombic unit cells. The lattice parameters increase with the incorporation of increasing amounts of tin, which is shown by x-ray absorption near edge structure investigation to be present as Sn4+. 57Fe Mössbauer spectroscopy indicates that iron in these phases is present as Fe5+ and Fe3+ and that the materials adopt the compositions SrFe0.69Sn0.31O2.94 and SrFe0.46Sn0.54O2.88. We propose that the disproportionation of Fe4+ in SrFeO3−δ to Fe5+ and Fe3+ in SrFe1−xSnxO3−δ is driven by the reduction of local lattice strain.

The materials have been fluorinated by reaction with poly(vinylidene fluoride) to give products of composition SrFe0.69Sn0.31O2.31F0.69 and SrFe0.46Sn0.54O2.54F0.46. The increased iron to oxygen or fluorine distances as revealed by the extended x-ray absorption fine structure are associated with the reduction of Fe5+ to Fe3+ as evidenced by 57Fe Mössbauer spectroscopy. The 57Fe Mössbauer spectra recorded from the fluorinated materials at low temperature show the coexistence of magnetic sextet and non-magnetic doublet components corresponding to networks of Fe3+ coupled through oxide ions. The Sn4+ ions disrupt the coupling and the size of the networks. The magnetic susceptibility measurements and Mössbauer spectra recorded between 4.2 and 300 K are used to model the magnetic properties of these materials, with the larger networks appearing to possess random spin orientations consistent with spin glass-type materials.

Item Type: Journal Article
Copyright Holders: 2009 IOP Publishing Ltd
ISSN: 0953-8984
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetCCLRC
Not SetNot SetEPSRC
Academic Unit/Department: Science > Life, Health and Chemical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Biomedical Research Network (BRN)
Item ID: 16572
Depositing User: Elaine Moore
Date Deposited: 29 May 2009 09:12
Last Modified: 07 Mar 2014 13:41
URI: http://oro.open.ac.uk/id/eprint/16572
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