Green synthesis and magnetothermal performance of Zn1−XONiX nanocomposites for magnetic hyperthermia applications

Abstract

Nickel-doped zinc oxide (Zn_1−XONi_X, X = 0.05–0.20) nanocomposites were synthesized via a simple and eco-friendly co-precipitation route and systematically investigated for their structural, thermal, magnetic, and magnetothermal properties. X-ray diffraction confirmed the hexagonal wurtzite phase at low Ni concentrations (≤5%), while weak NiO reflections emerged above 10%, revealing a solubility limit for Ni incorporation. Thermal analysis (TGA/DSC) indicated high stability above 450 °C with distinct exothermic crystallization associated with Ni incorporation. FTIR spectra confirmed Zn–O stretching vibrations along with hydroxyl and carbon-related groups. Magnetic measurements revealed weak room-temperature ferromagnetism, with the highest saturation magnetization of 0.117 emu g⁻¹ for Zn_0.85ONi_0.15, indicating optimal Ni substitution and defect-mediated exchange interactions. Under an alternating magnetic field (160 Oe, 468 kHz), Zn_0.85ONi_0.15 dispersions achieved a therapeutic hyperthermia threshold of 42 °C, with a specific absorption rate (SAR) of 9.2 W g⁻¹. These results demonstrate that Zn_1−XONi_X nanocomposites exhibit a relatively good magnetothermal response under an AMF, which needs to be optimized through polymeric surface functionalization and measurement under different frequency and field amplitudes.