Low-Temperature Sintering and Microwave Dielectric Properties of (1-x)MgTiO3–xCaTiO3Ceramics Using Bismuth Addition

The effects of bismuth addition on the microwave dielectric properties of (1- x )MgTiO 3 – x CaTiO 3 ceramics were investigated. MgTiO 3 –CaTiO 3 (hereafter referred to as MCT) ceramics was prepared by the conventional solid-state method. With a small amount of Bi 2 O 3 addition, the sintering temperature of MCT ceramics can be effectively lowered without degrading the dielectric properties at microwave frequency. At a constant Mg/Ca ratio, the Q × f values are strongly dependent on the amount of Bi 2 O 3 addition and decrease with increasing bismuth content owing to the decrease of density, while the ε r value only shows a small increase. In the (1- x )MgTiO 3 – x CaTiO 3 system, the microwave dielectric properties could be controlled by varying x . At 1250°C, 0.94MgTiO 3 –0.06CaTiO 3 ceramics with 0.2 mol% Bi 2 O 3 addition gives a dielectric constant ε r of 22.6, a Q × f value of 53000 (7 GHz) and a τ f value of -2.9 ppm/°C.