Internal and external variables influencing microwave dielectric properties of (1-x)Mg(Zr_0.05Ti_0.95)O₃-xSrTiO₃ ceramics

The physical and chemical state of ceramics are very important for their microwave dielectric properties, especially at high frequencies above GHz. Therefore, the microstructure and microwave dielectric properties of (1-x)Mg(Zr_0.05Ti_0.95)O₃–xSrTiO₃((1-x)MZT–xST) ceramics were investigated by controlling external variables. The compounds were synthesized through a solid-state reaction mechanism and sintered at relatively low temperatures. A cavity resonator method was employed to analyze the microwave dielectric properties. Optimal sintering conditions significantly enhanced the microwave dielectric performance of MZT–ST ceramics. The addition of ZnO substantially reduced the sintering temperature and equilibrium sintering time, enabling the activation of optimal conditions and the achievement of temperature-stable microwave dielectrics like NP0: ε_r ∼20.16 at 10 GHz, Q_f of ∼81839 GHz at 7.93 GHz, and τ_f close to zero (∼0.12 ppm/°C). This enhanced performance was attributed to the optimization of internal variables, including enhanced relative density, homogeneous grain size, optimal phase fraction, and chemical ordering.