Effect of Ce³⁺ doping on phase and microwave dielectric properties of 0.94MgTiO₃-0.06(Ca_0.8Sr_0.2)TiO_{3 ceramics}

In this study, 0.94Mg((1-3x/2))Ce(x)TiO(3)-0.06(Ca0.8Sr0.2)TiO3 (MCexT-CST, 0 <= x <= 0.01) composite ceramics were prepared at a low temperature of 1175 degrees C by using the 50-nm-sized powders. The effects of Ce3+ doping on crystalline phase, microstructure, and microwave dielectric properties of MCexT-CST were studied. A main ilmenite (Mg,Ce)TiO3 phase and a minor perovskite (Ca0.8Sr0.2)TiO3 phase coexist well with the appearance of impurity MgTi2O5 phase in MCexT-CST. The dielectric properties of MCexT-CST are affected by the molecular polarizability, the impurity phase, and the Ce3+ doping. The replacement of Mg2+ by high valence Ce3+ could effectively inhibit the formation of oxygen vacancy, resulting in the enhancement of Qxf. When x = 0.005, MCexT-CST exhibits microwave dielectric properties with a moderate epsilon(r) of 21.5, a high Qxf of 67 000 GHz, and a near-zero tau(f) of -0.74 ppm/degrees C. The results reveal that the Ce3+ substitution is a prospective approach to optimize the microwave dielectric properties of MgTiO3-based ceramics.