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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, T B , 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.

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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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