| LiZn ferrites are widely uesed in microwave devices due to their rectangular hysteresis loop,high curie temperature and low stress sensitivity of remanent magnetic induction.The effects of iron-deficient composition, additives and sintering-process on the electromagnetic properties of the low-dielectric loss LiZn ferrites were studied in this paper. As a result, the low dielectric loss LiZn ferrites were synthesized successfully at low sintering temperature.First, the effects of iron-deficient composition, additives and sintering-process on the electromagnetic properties of the LiZn ferrite prepared by conventional ceramic process were studied. The results showed that the addition of Bi2O3 can improve the densification behavior and grain growth, decrease the sintering-temperature and improve electromagnetic properties of LiZn ferrite, owing to a liquid phase sintering occurs during the sintering process. The addition of Mn3O4 can effectively restrains the appearance of Fe2+ ions during sintering process, improve the resistivity and magnetic properties of LiZn ferrite. Nb2O5 can refine grain size and improve the microstructure which then improve the resistivity and reduce the microwave dielectric loss of LiZn ferrite. Then the effects of iron deficiency on the microstructure and electromagnetic properties of LiZn ferrite were investigated. The results indicated that optimum iron deficiency can reduce the ferromagnetic resonance line-width and dielectric loss at 9.2GHz, enhance saturation and squareness ratio, and decrease coercive force. Optimum sintering parameters are beneficial to produce uniform grain structure and decrease the porosity, which then attributes to improve the properties of materials. Secondly, we successfully synthesized the series of nanometer powder of the LiZn ferrite by Sol-Gel citric acid self-propagating method, studied the influence of the rate of citric and the gelation temperature, And combined with conventional ceramic process, the effects of flux, iron deficiency and sintering process on electromagnetic properties of LiZn ferrite were investigated. The results showed that with the increase of citric acid, both the diameter of the power particle and specific saturation magnetization decrease. While bringing down the gelation temperature is beneficial to the formation of stable gel network which then enhances the specific saturation magnetization of nano-powder, improves the microstructure of singtering samples, increase the sturation magnetization and decreases the coercive force of LiZn ferrite. Bi2O3 could decrease the sintering-temperature and improve electromagnetic properties of LiZn ferrite. Optimum iron deficiency could improve the electromagnetic properties of LiZn ferrite and help to obtain LiZn ferrite with better properties at lower sintering temperature. |
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