Journal article

Magnetic properties of silica coated spindle-type hematite particles

  • Reufer, Mathias Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
  • Dietsch, Hervé Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
  • Gasser, Urs Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland - Laboratory for Neutron Scattering, Paul Scherrer Institut, Villigen, Switzerland
  • Grobéty, Bernard Department of Geosciences, University of Fribourg, Switzerland
  • Hirt, A. M. Institute of Geophysics, ETH Zürich, Switzerland
  • Malik, Vivek Kumar Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
  • Schurtenberger, Peter Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland - Physical Chemistry, Department of Chemistry, Lund University, Sweden
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    24.01.2011
Published in:
  • Journal of Physics: Condensed Matter. - 2011, vol. 23, no. 6, p. 065102
English Magnetic properties of particles are generally determined from randomly oriented ensembles and the influence of the particle orientation on the magnetic response is neglected. Here, we report on the magnetic characterization of anisotropic spindle- type hematite particles. The easy axis of magnetization is within the basal plane of hematite, which is oriented perpendicular to the spindle axis. Two standard synthesis routes are compared and the effects of silica coating and particle orientation on the magnetic properties are investigated. Depending on the synthesis route we find fundamentally different magnetic behavior compatible with either single domain particles or superparamagnetic sub-units. Furthermore, we show that silica coating reduces the mean blocking temperature to nearly room temperature. The mechanical stress induced by the silica coating appears to reduce the magnetic coupling between the sub-units.
Faculty
Faculté des sciences et de médecine
Department
Institut Adolphe Merkle, Département de Géosciences
Language
  • English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/301799
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