Optimized Zn substituted CoFe2O4 nanoparticles for high efficiency magnetic hyperthermia in biomedical applications

This study presents a systematic study on the structural, magnetic, and hyperthermia properties of Zn-substituted cobalt ferrite (Zn_xCo_1-xFe₂O₄, x = 0.0-0.7) nanoparticles synthesized via the hydrothermal method. X-ray diffraction patterns confirmed a pure spinel structure, with Rietveld refinement revealing cation redistribution and lattice distortions. Magnetic measurements showed a transition from ferrimagnetic (x ≤ 0.2) to superparamagnetic behavior (x ≥ 0.5), accompanied by a peak in saturation magnetization at x = 0.2 and a continuous decrease in coercivity. These changes were attributed to Zn-induced modulation of cation distribution and superexchange interactions. Magnetic hyperthermia studies demonstrated that Zn_0.6Co_0.4Fe₂O₄ exhibited the highest specific loss power (SLP) and intrinsic loss power (ILP) under alternating magnetic fields (65-125 Oe) and frequencies (250-350 kHz). The observed quadratic dependence of SLP on field amplitude confirmed adherence to linear response theory, with experimental conditions remaining within clinical safety limits. These findings highlight Zn_0.6Co_0.4Fe₂O₄ as an efficient candidate for magnetic hyperthermia applications, demonstrating tunable structural and magnetic properties for biomedical use.