X-Ray Study of the Behavior of a Commercial Ferrofluid

Authors:

• Students:
  • Isaac Banes
  • William Cashen
  • Kacper Cebula
  • Erion Duro
  • Kristjan Gudmunsson
  • Cassidy Hicks
  • Nidhi Kadiwala
  • Akash Magnadia
  • Harshitha Padiyar
  • Richard Phan
  • Aleksandra Typkheeva
• Teachers:
  • David Schultz
• Mentors:
  • Olaf Borkiewicz (Argonne National Laboratory, Advanced Photon Source, XSD-SRS)
  • Yang Ren (Argonne National Laboratory, Advanced Photon Source, XSD-SRS)
  • Uta Ruett (Argonne National Laboratory, Advanced Photon Source, XSD-SRS)
  • Kamila Wiaderek (Argonne National Laboratory, Advanced Photon Source, XSD-SRS)

Beamline: Advanced Photon Source Sector 11: Structural Science; Advanced Photon Source Sector 12: Chemical and Materials Science

Suspensions of iron nanoparticle-containing solutions known as ferrofluids are popularly used to demonstrate the presence of external magnetic fields and are also commonly used as thermal transfer agents and lubricants for mechanical components.  The dramatic behavior of ferrofluids is typically explained by the fact that they contain ferromagnetic nanoparticles which strongly respond to an outside magnetic field.  One possible model is that individual particles act like isolated magnetic domains which undergo alignment to the field.  Another model, akin to the alignment of domains within ferromagnetic solids, suggests that the field causes interparticle ordering that inhibits the normal, liquid-like freedom of the particles.

In this experiment, we use several x-ray diffraction methods to test the hypothesis that the nanoparticles in a commercially manufactured ferrofluid demonstrate magnetically influenced orientation and/or ordering behaviors.  Wide-angle x-ray scattering should reveal whether or not preferential orientation takes place within the average volume sampled within the beam path.  If particles align to the field, we expect to observe a modification to the isotropic pattern of rings commonly observed in powder patterns for polycrystalline samples.  If interparticle ordering occurs, whereby the magnetic alignment of one particle correlates with its neighbors, then we hope to observe correlations in interparticle distances revealed by the pair-distribution functions (pdf) for the particles.  It is possible that both orientational and ordering behaviors may be evident.  We will conduct our experiment at the high energy x-ray diffraction beamline at sector 11-ID-C, since this station is well suited for both techniques.

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