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Investigation of defect structures formed by doping tetravalent ions into spinel-related iron oxides using atomistic simulation calculations

Moore, Elaine; Bohorquez, A.; Berry, Frank; Helgason, O. and Marco, J.F. (2001). Investigation of defect structures formed by doping tetravalent ions into spinel-related iron oxides using atomistic simulation calculations. Journal of Physics and Chemistry of Solids, 62 pp. 1277–1284.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/S0022-3697(01)00021-X
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Abstract

Results from atomistic simulation calculations and X-ray photoelectron spectroscopy are used to define the proposed defect structures of gamma-Fe2O3 and Fe3O4 doped with tetravalent ions. These structures are of interest because of the effect of doping on the properties of the oxides. Calculations confirm that occupation by Sn4+ and Ti4+ of octahedral sites in Fe3O4 and gamma-Fe2O3 is more favourable than occupation of tetrahedral asites and indicate that the M4+ ions substitute on iron sites rather than occupy interstitial sites. For gamma-Fe2O3, XPS shows no reduction of Fe3+ occurs. Of the possible remaining balancing defects, calculations indicate that vacancies on the iron sites with six nearest-neighbour iron atoms are favoured. In the case of Fe3O4 results suggest that reduction of Fe3+ to Fe2+ is preferred and that reduction occurs on a site adjacent to M4+. This small cluster localises the disruption to the crystal structure. These results suggest that the pattern of doping by tetravalent ions in spinel-related iron oxides differs from that in the corundum-related alpha-Fe2O3.

Item Type: Journal Article
ISSN: 0022-3697
Keywords: oxides; ceramics; defects
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: 5582
Depositing User: Users 1688 not found.
Date Deposited: 19 Oct 2006
Last Modified: 07 Mar 2014 13:41
URI: http://oro.open.ac.uk/id/eprint/5582
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