Effect of heat treatment on the magnetic properties of nanocrystalline spinel Li-Ni ferrite prepared by a simple soft chemistry route

A simple soft chemistry route was developed to synthesize nanocrystalline Li-Ni ferrite (Li0.25Ni0.5Fe2.25O4). The as-prepared ferrite samples were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The effects of the annealing temperature on the particle sizes and magnetic properties of the synthesized Li-Ni ferrites were investigated. The results indicated that the ferrite samples obtained by this method had the single-phase spinel structure. Particle sizes estimated from Scherrer's formula increased with the annealing temperature. The magnetic properties of the ferrite samples showed strong dependence on the annealing temperature. The coercivity initially increased and then decreased with increasing annealing temperature whereas the saturation magnetization continuously increased.