Sintering behavior and microwave dielectric properties of Li4Mg3[Ti0.8(Mg1/3Ta2/3)0.2]2O9 ceramics with LiF additive for LTCC applications

Novel low temperature sintered Li 4 Mg 3 [Ti 0.8 (Mg 1/3 Ta 2/3 ) 0.2 ] 2 O 9 (LMT 0.8 (MT) 0.2 ) ceramics with 1–5 wt% LiF additives were successfully prepared by the solid-state reaction method. The effects of LiF additives on the phase composition, sintering characteristic, microstructure and microwave dielectric properties of LMT 0.8 (MT) 0.2 ceramics were investigated in detail for the first time. The sintering temperature of LMT 0.8 (MT) 0.2 ceramics could be effectively lowered to 950 °C by the addition of LiF. A single rock salt crystalline phase structure belonging to a space group of Fm-3m (No.225) was obtained through X-ray diffraction patterns. Dense uniform morphology was observed at 950 °C for LMT 0.8 (MT) 0.2 ceramics with 3–5 wt% LiF in terms of scanning electron microscopy photographs. Particularly, the LMT 0.8 (MT) 0.2 -4 wt% LiF ceramics sintered at 950 °C for 4 h possessed optimum microwave dielectric properties of ε r  = 16.10, Q·f  = 114,313 GHz (at 8.18 GHz) and τ f  = −7.72 ppm/°C. In addition, the excellent chemical compatibility with silver metal electrodes indicated that the LMT 0.8 (MT) 0.2 -4 wt% LiF ceramics might be a promising candidate for the low-loss low temperature co-fired ceramics (LTCC) applications in microwave devices.