Study of the effect of the Zn2 + content on the anisotropy and specific absorption rate of the cobalt ferrite: the application of Co1 − x Zn x Fe2O4 ferrite for magnetic hyperthermia

Zn-substituted cobalt ferrite nanoparticles with different zinc contents (Co1 − x Zn x Fe2O4, x = 0.25, 0.5, 0.75) were prepared through a novel combustion method and subsequent milling process. A magnetostriction test was conducted to investigate the migration of Co2+ ions away from the octahedral sites to confirm the decrease of the anisotropy as a result of the increase of the Zn content. The single domain and superparamagnetic behaviors in the obtained samples were analyzed, and their variations by the increase of Zn content were compared. The variations of anisotropy in the vicinity of various Zn contents were accessed, and the specific absorption rate of the obtained samples was estimated. Linear response theory showed that the ratio of the anisotropy energy to the thermal energy, as a dimensionless anisotropy parameter (σ), can have a key role in the specific absorption rate of any magnetic material in hyperthermia applications.