Please use this identifier to cite or link to this item: http://www.repositorio.ufop.br/handle/123456789/7820
Title: Mossbauer studies of magnetite and Al-substituted maghemites.
Authors: Costa, Geraldo Magela da
Grave, Eddy De
Vandenberghe, Robert Emile
Keywords: Maghemite
Magnetite
Al-substitution
Mossbauer spectroscopy
Issue Date: 1998
Citation: COSTA, G. M. da; DE GRAVE, E.; VANDENBERGHE, R. E. Mossbauer studies of magnetite and Al-substituted maghemites. Hyperfine Interactions, v. 117, p. 207-243, 1998. Disponível em: <https://link.springer.com/article/10.1023/A:1012691209853>. Acesso em: 20 abr. 2017.
Abstract: This paper reviews a systematic M¨ossbauer study of maghemite -Fe2O3 and Alsubstituted maghemites -(Fe1􀀀yAly)2O3. Three series of samples prepared from different methods and having different morphological characteristics and aluminum contents were investigated. It was found that both the cation distribution and the solubility limit depend on the preparation method, and no general conclusion in that respect could be inferred. From the temperature dependence of the hyperfine fields the exchange integrals could be calculated, and were found as: JAB = 􀀀25 K, JAA = 􀀀18 K, and JBB = 􀀀3 K. The hyperfine fields show a crossing in the vicinity of 300 K, for both substituted and unsubstituted samples, as a result of the relatively strong A–A interaction. The Curie temperatures were found to be in the range of 948–730 K, the lower value referring to the sample containing 22 mole% Al. The influence of maghemite on the M¨ossbauer spectra (MS) of magnetite was explored in some detail. It was demonstrated on the basis of the MS recorded for a variety of reference mixtures, that it is not possible to resolve the ferric A-site components due to maghemite and magnetite, even with the absorber subjected to a strong external field.
URI: http://www.repositorio.ufop.br/handle/123456789/7820
metadata.dc.identifier.uri2: https://link.springer.com/article/10.1023/A:1012691209853
ISSN: 15729540
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