Dielectric properties of ultralow-fired Mg4Nb2O9 ceramics co-doped with TiO2 and LiF

The Mg4Nb2O9 co-doped with 20 wt% TiO2 (MNT) and x wt% LiF (1 a parts per thousand currency sign x a parts per thousand currency sign 8) composite ceramics were prepared by a solid-state reaction method for developing ultralow-fired (a parts per thousand currency sign800 A degrees C) microwave dielectric ceramics. The sintering temperatures of MNT ceramics were successfully lowered to 750 A degrees C due to the formation of liquid phase (LiF). A secondary phase of MgTiO3 was observed at above 700 A degrees C for MNT-8 wt% LiF ceramics. All the composite ceramics have the optimal bulk densities at 800 A degrees C, which corresponds to the maximum Q x f value of 32,000 GHz and E > (r) value of 15.7. The well microwave dielectric properties of E > (r) = 15.6, Q x f = 25,000 GHz, and tau (f) = -56 ppm/A degrees C were obtained at 750 A degrees C for 5 h for MNT-8 wt% LiF ceramics. This material is compatible with Ag electrodes, suitable for low-temperature co-fired ceramics applications.