Sintering behaviour of lithium ferrites containing Nb2O5 and V2O5

Lithium ferrite toroids with various compositions and with various amounts of Nb₂O₅ or V₂O₅, have been prepared by a powder compacting method, and their sintering behaviours, microstructures and weight-loss characteristics have been investigated. The rate of sintering is higher in an Fe₂O₃-deficient lithium ferrite than in an Fe₂O₃-excess lithium ferrite due to the presence of excess oxygen vacancy in the Fe₂O₃-deficient lithium ferrite during sintering. The presence Of LiNbO₃ or LiVO₃, which is formed by Nb₂O₅ or V₂O₅, on the surface of lithium ferrite grains causes an increase in oxygen activity of the lithium ferrite and a decrease in the rate Of lithium evaporation during sintering, resulting in a strong enhancement in the sintering rate. The enhancing effect of V₂O₅ in the sintering Of lithium ferrite is stronger than that of Nb₂O₅ due to the possible formation of liquid V₂O, before the formation of LiVO₃.