Effect of Mg doping on magnetic induction heating of Zn–Co ferrite nanoparticles

Ferrite magnetic nanoparticles (MNPs) with spinel structure are of great significance in the study of magnetic induction hyperthermia (MIH). The effect of element doping on the magnetic properties of MNPs is crucial. Here, we report the influence of the Mg²⁺ substitution on Curie temperature (T_c), magnetic properties, and heating efficiency of Mg_xZn_0.8-xCo_0.2Fe₂O₄ (0.1 ≤ x ≤ 0.5) nanoparticles synthesized by hydrothermal method. With the increase of Mg²⁺ content, T_c increases from 36.7 °C to 242.9 °C due to the enhancement of the A-B super-exchange interaction. The specific saturation magnetization increases from 35.5 emu·g⁻¹ to 53.3 emu·g⁻¹ and then remains constant, which is caused by the effect of Yafet-Kittle angle and magnetic moment. The specific absorption rate (SAR) increases from 3.5 W·g⁻¹to 82.7 W·g⁻¹, which may be ascribed to the effect of size and specific saturation magnetization of the nanoparticles. When x = 0.3, the stable temperature under the alternating magnetic field (32 kA·m⁻¹, 100 kHz) reaches 44.7 °C with the SAR of 49.0 W·g⁻¹. The low toxicity to cells and high heating efficiency endow the MNPs the potential in MIH.