Dual-enhancement of microwave dielectric properties and sintering performance of MgF₂ doped MgTi_1-x(Mn_1/3Sb_2/3)_xO₃ ceramics

High Q·f value and temperature-stable MgF₂-doped MgTi_1-x(Mn_1/3Sb_2/3)_xO₃ ceramics have been successfully prepared by the solid-state reaction method. Microwave dielectric properties and sintering performance of MgF₂-doped MgTi_1-x(Mn_1/3Sb_2/3)_xO₃ ceramics were systematically investigated by the classic theory and the P-V-L theory. The results show that MgF₂ doping and complex cation (Mn_1/3Sb_2/3)⁴⁺ substitution not only further reduces the sintering temperature of MgTiO₃ ceramics from 1400 °C to 1250 °C, but also effectively improves the quality factor from 110210 GHz to 228713 GHz and adjust the τf value from −53.55 ppm/°C to −20.42 ppm/°C. The ionicity, the bond valence and octahedral distortion confirmed that Ti/(Mn_1/3Sb_2/3)-O bonds exert a greater influence on microwave dielectric properties than Mg-O bonds in MgTiO₃ ceramics, which provides a guide to further improve the microwave dielectric performances. The optimal microwave dielectric properties: ε_r = 18.8 ± 0.28, Q·f = 228713 ± 2500 GHz (at 6.08 GHz), τ_f = (−20.42 ± 1.1) ppm/°C were achieved for 3 wt% MgF₂ doped MgTi_0.99(Mn_1/3Sb_2/3)_0.01O₃ ceramics sintered at 1250 °C.