Heat generation in agglomerated ferrite nanoparticles in an alternating magnetic field

E. DE BIASI; E. LIMA JR.; M VASQUEZ MANSILLA; M. E. SALETA; M. GRANADA; H. E. TROIANI; F. E. EFFENBERG; L. M. ROSSI; H. R. RECHENBERG; R. D. ZYSLER

Buenos Aires

Workshop; Latin America Workshop on Magnetism, Magnetic Materials and their Applications; 2013

The role of agglomeration and magnetic interparticle interactions on the heating generation of magnetic ferrofluids in an ac magnetic field is unclear until now, with apparently discrepancy. In the results presented in the literature. In this work, we have measured the heating generation capability of agglomerated ferrite nanoparticles with large hydrodynamic diameter, where the mechanical relaxation mechanism can be not taken into account) for the non-invasive ac magnetic field with f =100 kHz and H0 = 13 kA/m. The nanoparticles were morphological and magnetically characterized, and de SAR presents a clear dependence with the diameter of the nanoparticles, with a maximum of SAR = 48 W/g at 15 nm. We also present a model that simulates the SAR dependence of agglomerated samples with the diameter of the nanoparticles based on the hysteresis losses that is valid for the non-linear region (with H0 comparable to anisotropy field). Our model takes into account the magnetic interactions among the agglomerate nanoparticles. For comparison, we also measured the SAR of non-agglomerated nanoparticles in a similar diameter range.