Abstract
Due to their bio-compatibility and non-toxicity, ferrimagnetic iron oxides are suitable for various medical applications. In the case of hyperthermia, the promising approach how to reach desired magnetic properties is to combine more phases into a composite material.
A series of samples containing maghemite and M-hexaferrite was prepared by sol gel method with subsequent thermal treatment where annealing temperature and time were varied. The samples were characterized by X-ray diffraction.
In this paper we focused mainly on application of nuclear magnetic resonance spectroscopy to investigate these strongly inhomogeneous nanopaxticle composites. Frequency-swept Fe-57 NMR spectra of nanoparticle samples were measured in a zero external magnetic field at 4.2 K.
Utilizing differences in optimal excitation field strengths and in relaxation times, we were able to resolve NMR signal assigned to hexagonal ferrite of M-phase from signal which showed features attributed to maghemite.