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Nanophase Molecular Antiferromagnets

Published online by Cambridge University Press:  25 February 2011

Georgia C. Papaefthymiou
Georgia C. Papaefthymiou*
Affiliation:
Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139
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Abstract

Nanometer-sized molecular complexes of superexchange-coupled iron ions with iron nuclearity n < 10 exhibit short-range intramolecular magnetic ordering and ‘particlelike’ superparamagnetism in their low temperature Mössbauer spectra. A comparative study of the magnetic properties of ca 10 Å diameter iron-oxo phases obtained through controlled hydrolytic polymerization of iron in non-aqueous solvents is presented. The magnetic anisotropy energy constant, K, which is proportional to the observed blocking temperature, TB, and the sharpness of the superparamagnetic transition depend critically on the iron oxidation state and degree of 3d-electron delocalization. Representative examples of mixed-valent iron complexes containing oxo-bridged, octahedrally coordinated iron with primarily either Fe(III) or Fe(II) character are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 286: Symposium J – Nanophase and Nanocomposite Materials , 1992 , 267
Copyright
Copyright © Materials Research Society 1993

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References

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