Microstructure and microwave dielectric properties of xSm(Mg0.5Ti0.5)O3–(1 − x)Ca0.8Sr0.2TiO3 ceramics

xSm(Mg0.5Ti0.5)O3–(1 − x)Ca0.8Sr0.2TiO3 (x = 0.50–0.95) ceramics are prepared by a conventional solid-state ceramic route. The microstructure and microwave dielectric properties are investigated as a function of the x-value and sintering temperature. The single phase solid solutions were obtained throughout the studied compositional range. The variation of bulk density and dielectric properties are related with the x-value. Increasing sintering temperature can effectively promote the densification and dielectric properties of xSm(Mg0.5Ti0.5)O3–(1 − x)Ca0.8Sr0.2TiO3 ceramic system. With the content of Sm(Mg0.5Ti0.5)O3 increasing, the temperature coefficient of resonant frequency τf value decreased, and a near-zero τf could be obtained for the samples with x = 0.80. The optimal microwave dielectric properties with a dielectric constant εr of 30.1, Q × f of 115,000 GHz (at 8.0 GHz), and τf of 8.9 ppm/°C were obtained for 0.80Sm(Mg0.5Ti0.5)O3–0.20Ca0.8Sr0.2TiO3 sintered at 1,550 °C for 3 h, which showed high density and well-developed grain growth.