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 ɛr of 20, a Q × f value of 65,000 (at 7 GHz) and a τf 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.