In Situ Dimensional Characterization of Magnetic Nanoparticle Clusters during Induction Heating

The study and fundamental understanding of magnetic nanoparticle induction heating remains critical for the advancement of magnetic hyperthermia technologies. Complete characterization of not only the nanoparticles themselves but their interparticle behavior in a sample matrix is necessary to accurately predict their heating response. Herein, an in situ method for measuring the extent of nanoparticle clustering during induction heating using small-angle and ultrasmall-angle neutron scattering facilities at the National Institute of Standards and Technology Center for Neutron Research is described and implemented by comparing two sets of iron oxide nanoparticles with differing structures and magnetic properties. By fitting the scattering profiles to a piecewise model covering a wide Q-range, the magnitude of nanoparticle clustering during induction heating is quantified. Observations of the low-Q intensity before and after heating also allow for relative measurement of the cluster volume fraction during heating. The use of this method can prove to be advantageous in both developing more encompassing models to describe magnetic nanoparticle dynamics during heating as well as optimizing nanoparticle synthesis techniques to reduce aggregation during heating.