Processing And Property Study Of Li₂ZnTi₃O₈-based Microwave Dielectric Ceramics

Li₂ZnTi₃O₈-based ceramics are chosen as the research objective in this article. Ionsubstitution and oxide doping were used to adjust the microwave dielectric properties ofLi₂ZnTi₃O₈-based ceramics. H₃BO₃and ZnO-B₂O₃frit were chosen to decrease thesintering temperature of the ceramics.Li₂Mg_xZn_1-xTi₃O₈solid solution was prepared by using Mg²⁺to substitute the Zn²⁺ofthe Li₂ZnTi₃O₈ceramics. It is found that εrand τfincrease as the increase of the x value. TheLi₂Mg_xZn_1-xTi₃O₈ceramics get the max Q×f value, when x=0.6, which may be caused bythe ion ording of the ceramics. As the increase of the sintering temperature, εrand Q×fvalue increase firstly and then have the trend of decrease, and the optimal sinteringtemperature is1225℃.To adjust the microwave dielectric properties of the Li₂ZnTi₃O₈ceramics, moderateamount of TiO₂was added into the samples. By adding small amount of TiO₂, the Q×fvalue increases as the increase of the density. As the content of TiO₂increases, the Q×fvalue has the trend of decrease and the optimal addition content of TiO₂is0.5wt%.Because of small low volume fraction of TiO₂, it has little effect on εrof Li₂ZnTi₃O₈ceramics. The change of the τfvalue is complicated, which needs future investigate. As theincrease of the sintering temperature, εrand Q×f value increase firstly and then have thetrend of decrease, and the optimal sintering temperature is1200℃. To lower the sinteringtemperature of the Li₂ZnTi₃O₈ceramics and adjust their microwave dielectric properties,moderate amount of SiO₂was added into the samples. Because of the small volume fractionthat SiO₂occupies in the whole system, it has little effect on εrand τfof Li₂ZnTi₃O₈ceramics. SiO₂melts to liquid phase during the sintering process, which increases thedensity of the ceramics and it benefits to the improvement of the Q×f value. Excess liquidphase with high loss can decrease the Q×f value of the ceramics and the optimal additioncontent of SiO₂is0.2wt%. As the increase of the sintering temperature, the Q×f valueincrease firstly and then have the trend of decrease, and the optimal sintering temperature is1150℃. To decrease the sintering temperature of Li₂ZnTi₃O₈ceramics, H₃BO₃and ZnO-B₂O₃frit were chosen as the sintering aid, and both of them can lower the sintering temperatureof the ceramics from1200℃to900⁹50℃. H₃BO₃has little effect on εrand τfofLi₂ZnTi₃O₈ceramics. Small amount of H₃BO₃can increase the Q×f value by increasing thedensity of the ceramics. When the content of the H₃BO₃is excess, the Q×f value willdecrease, and the optimal addition content is2.0wt%. Small amount of ZnO-B₂O₃frit isbeneficial to the sintering process and it can increase εrand the Q×f value. ExcessZnO-B₂O₃frit willdeteriorate the microwave dielectric properties of the ceramics and theoptimal addition content is0.25wt%.