Improving microwave dielectric properties of temperature - compensated Mg(1.04-1.5y)CeyTiO3 - based Ceramics with high quality factor

The phase formation, microstructure, chemical structure, and microwave (MW) dielectric properties of the composite ceramics (1-x)Mg(1.04-3/2y)CeyTiO3-xCaTiO3 (MCT-CT) have been investigated systematically. The CaTiO3 and MgTiO3 phases coexist well with the formation of secondary phase MgTi2O5 based on X-ray diffraction. Chemical structure analysis reveals the existence of oxygen vacancies (VO
-
- ) whose concentrations increase with x, which consequently induce microwave dielectric loss. It has demonstrated that the behaviors of Q×f are influenced strongly by the phase composition and vacancy defects. Although an increasing amount of CaTiO3 can improve the dielectric constant (εr) of the sample slightly, it renders a decrease in the Q×f value instead. The τf value is strongly correlated to the compositions and the existing phases that can be controlled. An excellent combination of the MW dielectric properties εr∼23, Q×f∼70, 800 GHz, and τf∼0 ppm/°C was obtained at x=0.08, sintered at an optimal temperature of 1300 °C/3 h.