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The influence of ruthenium on the magnetic properties of γ-Fe2O3 (maghemite) studied by Mössbauer spectroscopy

Helgason, Orn; Greneche, Jean-Marc; Berry, Frank J. and Mosselmans, Frederick (2003). The influence of ruthenium on the magnetic properties of γ-Fe2O3 (maghemite) studied by Mössbauer spectroscopy. Journal of Physics: Condensed Matter, 15(17) pp. 2907–2915.

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Ruthenium-doped gamma-Fe2O3 has been synthesized and examined by x-ray powder diffraction, XANES, EXAFS and by Fe-57 Mossbauer spectroscopy. Ruthenium K-edge x-ray absorption spectroscopy shows that ruthenium adopts a fully occupied octahedral site in the spinel related gamma-Fe2O3 structure as Ru4+. The Fe-57 Mossbauer spectra recorded in the presence of a longitudinal magnetic field of 6 T confirmed the octahedral coordination of the tetravalent ions and canting angles for the Fe3+ ions were determined as 24degrees for those in octahedral sites and 33degrees for those in tetrahedral sites. The Fe-57 Mossbauer spectra recorded in situ from ruthenium-doped gamma-Fe2O3 showed parameters typical of maghemite up to 600 K but with a magnetic hyperfine field distribution suggesting an inhomogeneous distribution of ruthenium within particles of varied size around about 15 nm. At 700 K a phase transition from gamma-Fe2O3 to alpha-Fe2O3 was observed and further studies showed the ruthenium-doped alpha-Fe2O3 to have a Morin transition temperature of about 400 K.

Item Type: Journal Article
ISSN: 0953-8984
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
Academic Unit/Department: Science > Life, Health and Chemical Sciences
Item ID: 5754
Depositing User: David Shuker
Date Deposited: 09 Nov 2006
Last Modified: 14 Jan 2016 16:16
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