Nickel ferrite: Advances in the synthesis methods, properties and its applications

Abstract

Nickel ferrites (NiFe₂O₄) have gained attention for their excellent magnetic properties, including high magnetic permeability, low magnetic losses, and moderate coercivity, making them ideal for applications in electronics, telecommunications, magnetic sensors, and energy storage systems. Nickel ferrites have been prepared using a variety of synthesis processes, including sol-gel, co-precipitation, hydrothermal, microwave-assisted, and solvothermal. Each approach has a considerable impact on particle size, crystallinity, and magnetic characteristics. Bulk NiFe₂O₄ has a saturation magnetization (M_s) of ∼50–55 emu/g, coercivity (H_c) of 100–200 Oe, and Curie temperature (T_c) of ∼585°C, making it ideal for soft magnetic applications. Elemental doping (e.g., Zn, Mg, Co, and rare earth metals) alters the cation distribution, magnetic interactions, and structural features, allowing for customized performance. Zn²⁺ doping increases M_s by up to ∼60 emu/g, while rare-earth doping decreases M_s, making photocatalytic and energy storage applications more efficient. Nickel ferrites are widely used in catalysis (e.g., dye degradation, heavy metal removal, and photocatalysis), energy storage devices (e.g., supercapacitors with capacitance ∼650 F/g, lithium-ion batteries with specific capacities ∼850 mAh/g), and biomedical fields (e.g., magnetic hyperthermia and MRI contrast agents).