Effect of ZnO additive on sintering behavior and microwave dielectric properties of 0.95MgTiO₃-0.05CaTiO₃ ceramics

The effects of ZnO additive on the microstructures, the phase formation and the microwave dielectric properties of MgTiO₃-CaTiO₃ ceramics were investigated. The sintering temperature of ZnO-doped 0.95MgTiO₃-0.05CaTiO₃ ceramics can be lowered to 1300 °C due to the liquid phase effect. Formation of second phase MgTi₂O₅ can be effectively restrained through the addition of ZnO. The microwave dielectric properties are found strongly correlated with the sintering temperature as well as the amount of ZnO addition. At 1300 °C, 0.95MgTiO₃-0.05CaTiO₃ ceramics with 1 wt% ZnO addition possesses a dielectric constant ε_r of 20, a Q × f value of 65,000 (at 7 GHz) and a τ_f value of -5.8 ppm/°C. In comparison with pure 0.95MgTiO₃-0.05CaTiO₃ ceramics, the doped sample shows not only a 16% loss reduction but also a lower sintering temperature. That makes it a very promising material to replace the present one for GPS patch antennas.