Microstructures and microwave dielectric properties of Mg₂SiO₄–Ca_0.9Sr_0.1TiO₃ ceramics

The microstructures and microwave dielectric properties of (1 − x)Mg₂SiO₄–xCa_0.9Sr_0.1TiO₃ (x = 0.05–0.08) composite ceramics, prepared via a conventional solid-state ceramic route, were investigated. As expected, an increase in sintering temperature effectively promoted densification and enhanced the dielectric properties of the (1 − x)Mg₂SiO₄–xCa_0.9Sr_0.1TiO₃ ceramics used in this study. As the amount of Ca_0.9Sr_0.1TiO₃ increased, temperature coefficient of resonant frequency (τ_f) increased; with a near-zero τ_f obtained for samples where x = 0.06. The optimal microwave dielectric properties, a dielectric constant (ε_r) of 8.01, high quality factor (Q × f) of 58,389 GHz (at 14.6 GHz) and a τ_f of −3.62 ppm/°C, were obtained for 0.94Mg₂SiO₄–0.06Ca_0.9Sr_0.1TiO₃ sintered at 1,440 °C for 3 h.