Tuning sintering temperature and microwave dielectric properties of MgGa2O4 ceramics via LiF addition for LTCC applications

This study demonstrates the successful synthesis of (1-x)MgGa2O4- xLiF (x = 0.1-0.4, mass fraction) ceramics via solid-state reaction, achieving a significant reduction in sintering temperature from 1410 to 850 degrees C. The XRD and Raman testing results showed the formation of a new phase of LiGaO2, which affected the dielectric properties. Variations in the sintering density and ionic polarizability cause changes in the permittivity. In addition, the packing fraction analysis of MgGa2O4, which influences the crystal structure stability, elucidates the intrinsic mechanisms affecting the dielectric loss. The composite effect makes the tau f value of the ceramic shift toward the negative value, owing to the large negative frequency temperature coefficient of LiF. Finally, (1-x)MgGa2O4-xLiF (x = 0.3) sintered at 850 degrees C possesses the superior dielectric properties: epsilon r = 9.45, Q x f = 32,790 GHz, tau f = -28.5 ppm/degrees C (at 14 GHz). In addition, (1-x)MgGa2O4-xLiF (x = 0.3) ceramics exhibit good cofiring compatibility with Ag electrodes promoting the ceramic to be a suitable candidate for LTCC applications.