Fabrication, sinterability and microwave dielectric properties of MgTiO3−(Ca0.8Sr0.2)TiO3 composite ceramics from nanosized powders

In this study, (1-x)MgTiO3−x(Ca0.8Sr0.2)TiO3 (0.04 ≤ x ≤ 0.09, (1-x)MT−xCST) composite ceramics were prepared using the 50 nm-sized powders that were synthesized by chemical precipitation method. Due to the high sintering activity of the nanosized powders, the densified MT−CST ceramics can be obtained at sintering temperature as low as 1175 °C. The obtained MT-CST ceramics contain a main ilmenite MgTiO3 phase and a minor perovskite (Ca0.8Sr0.2)TiO3 phase. The oxygen vacancy-related dielectric relaxation phenomenon is found in all MT−CST composite ceramics, which could lead to the microwave dielectric loss. The microwave dielectric properties of MT−CST ceramics can be regulated by adding CST. When x = 0.06, the 0.94MT−0.06CST ceramics sintered at 1175 °C exhibit great microwave dielectric properties with εr = 20.6, Q×f = 54,000 GHz, and τf = 0.22 ppm/°C. The results reveal that the preparation of microwave dielectric ceramics with nanosized powders can effectively reduce the sintering temperature and obtain excellent microwave dielectric properties.