Low-Temperature Sintering and Microwave Dielectric Properties of (1-<i>x</i>)MgTiO₃–<i>x</i>CaTiO₃Ceramics Using Bismuth Addition

Abstract

The effects of bismuth addition on the microwave dielectric properties of (1-x)MgTiO3–xCaTiO3 ceramics were investigated. MgTiO3–CaTiO3 (hereafter referred to as MCT) ceramics was prepared by the conventional solid-state method. With a small amount of Bi2O3 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 Bi2O3 addition and decrease with increasing bismuth content owing to the decrease of density, while the εr value only shows a small increase. In the (1-x)MgTiO3–xCaTiO3 system, the microwave dielectric properties could be controlled by varying x. At 1250°C, 0.94MgTiO3–0.06CaTiO3 ceramics with 0.2 mol% Bi2O3 addition gives a dielectric constant εr of 22.6, a Q×f value of 53000 (7 GHz) and a τf value of -2.9 ppm/°C.