CoFe2-xRExO4 (RE=Dy, Yb, Gd) magnetic nanoparticles for biomedical applications

Abstract

Nanoparticles with general formula CoFe2-xRExO4 (RE = Yb, Dy, Gd; x = 0.0–0.3) were synthesized by the co-precipitation and heat treated for potential application in magnetic hyperthermia. The influence of RE doping on structural, magnetic and thermal properties has been investigated. The RE cations enter the spinel lattice as detected by X-ray diffraction. Thermal treatment leads to thermodynamically stable and relaxed single-phase spinel structures only for lower RE content, x = 0.01–0.05. The annealed samples present higher mass magnetization values up to 83 Am2/kg. In the case of annealed samples saturation magnetization decreases linearly from 83 Am2/kg (x = 0.01) to about 60 Am2/kg (x = 0.30). Thermal treatment induces a reduction in coercivity from 60 to 100 mT for as-prepared samples to 18–33 mT for annealed samples. Heating efficiency, i.e., Specific Loss Power of all samples has been studied using both magnetometric and calorimetric method to examine the energy loss mechanisms.