Sintering behavior, structural evolution, and dielectric properties of Li3Mg3NbO7 3 Mg 3 NbO 7+ x wt% LiF microwave dielectric ceramics

In this paper, x wt% LiF (1 <= x <= 10) is utilized to decrease sintering temperature, improve microstructure and enhance Q x f of Li3Mg3NbO7 3 Mg 3 NbO 7 ceramics. Remarkably, the appropriate addition of LiF leads to the dramatic reduction in sintering temperature (reduced by 300 degrees C) and the significant improvement in Q x f (increase ratio: 26 %). The addition of LiF causes the generation of cubic oxyfluoride solid solution, which is confirmed by XRD, SEM and TEM. When x <= 8, both orthorhombic oxide and cubic oxyfluoride solid solution exist in ceramics. When x = 10, the ceramic is composed of cubic oxyfluoride solid solution and LiF. It is confirmed that the maximum mass percentage of LiF required to fully form a cubic solid solution is between 8 wt% and 10 wt%. The significant improvement in Q x f is mainly attributed to increase in relative density and orthorhombic-cubic phase transition. In this system, Li3Mg3NbO7 3 Mg 3 NbO 7 + 8 wt% LiF ceramics sintered at 900 degrees C possess the optimal dielectric properties: epsilon r r = 14.10, Q x f = 152,510 GHz and tau f f =-43.5 ppm/degrees C. degrees C. The Li3Mg3NbO7 3 Mg 3 NbO 7 + 8 wt% LiF ceramics show an outstanding combination of low epsilon r , high Q x f and low sintering temperature, surpassing the performance of most low-temperature dielectric materials. The excellent chemical compatibility with Ag electrodes suggests that the Li3Mg3NbO7 3 Mg 3 NbO 7 + 8 wt% LiF ceramics are particularly promising for LTCC applications.