Dielectric properties of ultralow-fired MgNbO ceramics co-doped with TiO and LiF.

The MgNbO co-doped with 20 wt% TiO (MNT) and x wt% LiF (1 ≤ x ≤ 8) composite ceramics were prepared by a solid-state reaction method for developing ultralow-fired (≤800 °C) microwave dielectric ceramics. The sintering temperatures of MNT ceramics were successfully lowered to 750 °C due to the formation of liquid phase (LiF). A secondary phase of MgTiO was observed at above 700 °C for MNT-8 wt% LiF ceramics. All the composite ceramics have the optimal bulk densities at 800 °C, which corresponds to the maximum Q × f value of 32,000 GHz and ɛ value of 15.7. The well microwave dielectric properties of ɛ = 15.6, Q × f = 25,000 GHz, and τ = −56 ppm /°C were obtained at 750 °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. [ABSTRACT FROM AUTHOR]