Effect of Ta₂O₅ additive on the properties of (Mg_0.75Zn_0.25)TiO₃ ceramics with high frequency and high Q-value

The (Mg_0.75Zn_0.25)TiO₃ ceramics with Ta₂O₅ additive were prepared with solid-state reaction method. Ta₂O₅ as an additive effectively lowered the sintering temperature to 1100 °C and improved the microstructure of the ceramics. Ta⁵⁺ was completely incorporated into the (Mg_0.75Zn_0.25)TiO₃ lattice to form the ilmenite phase (R-3), alongside the emergence of a second phase, MgTi₂O₅. The increasing content of the second phase caused the cell volume of the main phase to increase. When the Ta₂O₅ content is less than 5 wt%, the density of the ceramics has the main effect on the ε_r, while above 5 wt%, the second phase plays a dominant role in the ε_r of the ceramics. The results showed that when the additive of Ta₂O₅ is 2 wt%, the ceramics sintered at 1100 °C for 3 h exhibited the excellent microwave dielectric properties of Q × f ~ 108,726 (at 7.9 GHz), ε_r ~ 18.73 and τ_f ~  − 59.76 ppm/°C.