Hostname: page-component-745bb68f8f-5r2nc Total loading time: 0 Render date: 2025-02-04T16:45:46.950Z Has data issue: false hasContentIssue false
  • English
  • Français

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
Get access

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Stucky, G.D. and MacDougall, J.E., Science 247, 669 (1990).Google Scholar
2. Ceshnovsky, O. et al. , Phys. Rev. Lett. 64, 1785 (1990); A.M. Thayer et al., ibid., 60, 1673 (1988); Elemental and Molecular Clusters, edited by G. Benedek, T.P. Martin, and G. Pacchioni (Springer, Berlin, 1988).Google Scholar
3. Gunther, L., Phys. World 3.28 (December, 1990).Google Scholar
4. Biomineralization, edited by Mann, S., Webb, J., and Williams, R.J.P. (VCH Publishers, New York, 1989).Google Scholar
5. Stark, D.D. et al. , Radiology 168, 297 (1988); P.A. Hardy and R.M. Henkelman, Magn. Res. Imag. 7,265 (1989).Google Scholar
6. Papaefthymiou, G.C., Phys. Rev. B 46, 10366 (1992).Google Scholar
7. Micklitz, W. and Lippard, S.J., J. Am. Chem. Soc 111, 6856 (1989).Google Scholar
8. Taft, K.L., Papaefthymiou, G.C. and Lippard, S.J., Science (in press).Google Scholar
9. Micklitz, W., McKee, V., Papaefthymiou, G.C., Rardin, R.L., Bott, S.G. and Lippard, S.J., in preparation.Google Scholar
10. Greenwood, N.N. and Gibb, T.C., Mõssbauer Spectroscopy (Chapman and Hall, London, 1971).Google Scholar
11. Murray, K.S., Coord. Chem. Rev. 12, 1 (1974); D.M. Kurtz, Jr., Chem. Rev. 90, 585 (1990).Google Scholar
12. Kündig, W. et al. , Phys. Rev. 142, 327 (1966); S. Morup etal., J. Phys. 51, 6 (1976).Google Scholar
13. Rancourt, D.G., Hyperfine Interact. 40, 183 (1988).Google Scholar
14. McNabb, T.K. et al. , J. Appl. Phys. 39, 5703 (1968).Google Scholar
15. Abragam, A. and Bleaney, B., Electron Paramagnetic Resonance of Transition Ions (Dover Publications, Inc., New York, 1986).Google Scholar
16. Morup, S. et al. , J. de Phys. 37, C6–287 (1976).Google Scholar