Synthesis and magnetic properties of Co1−x Zn x Fe2O4+γ nanoparticles as materials for magnetic fluid hyperthermia

Abstract: Nanoparticles of the single spinel phase Co1−x Zn x Fe2O4+γ of mean size 3–23nm, as determined by X-ray diffraction analysis, were synthesized by the co-precipitation method followed by a temperature treatment. Magnetic studies carried out in the range of 4.5–550K revealed gradual transition from ferrimagnetic to superparamagnetic to paramagnetic behaviour depending on the composition and particle size. The observed behaviour indicates a broad distribution of volume sizes of the nanoparticles. Particular importance can be ascribed to the composition of x=0.6 where the observed transition temperature to the paramagnetic state at 310–334K suggests applicability of this material for magnetic fluid hyperthermia in a self-controlled regime. [Copyright &y& Elsevier]