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 (ZnxCo1-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 Zn0.6Co0.4Fe2O4 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 Zn0.6Co0.4Fe2O4 as an efficient candidate for magnetic hyperthermia applications, demonstrating tunable structural and magnetic properties for biomedical use.