Dielectric characteristics and sintering behavior of Mg2TiO4-(Ca0.8Sr0.2)TiO3 ceramic system at microwave frequency

The microstructure and the microwave dielectric properties of (1 − x)Mg2TiO4-x(Ca0.8Sr0.2)TiO3 ceramic system prepared by the mixed oxide route have been investigated. The phases of Mg2TiO4 and (Ca0.8Sr0.2)TiO3 were co-existed as a two-phase system, which was confirmed by the XRD patterns and the EDX analysis. The microwave dielectric properties of the specimens are strongly related to the sintering temperature and the density. Sintering temperature of pure Mg2TiO4 can be lowered by adding (Ca0.8Sr0.2)TiO3. Combination of Mg2TiO4 (spinel-structured) and (Ca0.8Sr0.2)TiO3 (perovskite-structured) also leads to a zero τf. Consequently, a high Q × f of 90,500 GHz (measured at 9.5 GHz) associated with a ɛr of 18.3 and a τf of 0 ppm/°C can be achieved by using 0.91Mg2TiO4-0.09(Ca0.8Sr0.2)TiO3 ceramics at 1300 °C for 4 h. It is proposed as a very promising dielectric for microwave applications requiring low dielectric loss.