Influences of Bi₂O₃/V₂O₅ Additives on the Microstructure and Magnetic Properties of Lithium Ferrite

Lithium ferrite materials with different concentrations of Bi₂O₃ and V₂O₅ additives are prepared by the conventional ceramic technique. The x-ray diffraction analysis proves that the additives do not affect the final crystal phase of the lithium ferrite in our testing range. Both Bi₂O₃ and V₂O₅ additives could promote densification and lower sintering temperature of the lithium ferrite. The average grain size first increases, and then gradually
decreases with the Bi₂O₃ content. The maximal grain size appears with 0.25wt% Bi₂O₃. The average grain size first increases, and then is kept almost unchanged with the V₂O₅ content. The maximal average grain size of the samples with V₂O₅ additive is much smaller than that of the samples with Bi₂O₃ additive. Furthermore, the V₂O₅ additive more easily enters the crystal lattice of the lithium ferrite than the Bi₂O₃ additive. These characteristics evidently affect the magnetic properties, such as saturation flux density, ratio of remanence B_r to saturation flux density B_s, and coercive force of the lithium ferrite. The mechanisms involved are discussed.