Journal article

Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle x-ray scattering

  • 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 Laboratory for Neutron Scattering, ETH Zrich & Paul Scherrer Institut, Villigen, Switzerland
  • Hirt, Ann Institute for Geophysics, ETH Zürich, Switzerland
  • Menzel, Andreas Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
  • Schurtenberger, Peter Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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    23.03.2010
Published in:
  • Journal of Physical Chemistry B. - 2010, vol. 114, no. 14, p. 4763-4769
English Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core−shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The orientational order is determined from the SAXS data and compared to the orientational order obtained from magnetometry. The direct access to both, the orientational order of the particles, and the magnetic moments allow one to determine the magnetic properties of the individual spindle-type hematite particles. We study the influence of the silica coating on the magnetic properties and find a fundamentally different behavior of silica-coated particles. The silica coating reduces the effective magnetic moment of the particles. This effect is enhanced with field strength and can be explained by superparamagnetic relaxation in the highly porous particles.
Faculty
Faculté des sciences
Department
Adolphe Merkle Institute
Language
  • English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/301628
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