Improvement of the magnetization and heating ability of CoFe₂O₄/NiFe₂O₄ core/shell nanostructures

Abstract In this study, the effect of the shell thickness on the structural and magnetic properties of the CoFe 2 O 4 /NiFe 2 O 4 core/shell is studied. A single-phase core/shell nanocomposite was prepared by the hydrothermal method. The shell thickness was found to control the magnitudes of saturation magnetization and coercive field of the prepared samples. The thickness of the NiFe 2 O 4 , which covered cubic CoFe 2 O 4 particles of 15 nm, was 1.8 nm, leading to an increase in the saturation magnetization by 26% and a decrease in the coercive field by 50% compared to bare CoFe 2 O 4 . However, a further increase in shell thickness caused interfacial dislocations due to the lattice mismatch between the core and the shell. Finally, specific absorption rate (SAR) at high frequency was measured for all samples. Comparing the temperature rise under the influence of AC magnetic field, which indicates power loss, relative to bare CoFe 2 O 4 , it was enhanced by 100% for a shell thickness of 26 nm. The results of this study point to potential applications for these samples in the field of magnetic hyperthermia for cancer therapy and drug delivery.