The ultralow loss Li2Mg3Ti1−xAl4x/3O6 microwave dielectric ceramics and its design of dielectric resonator antenna

The Li 2 Mg 3 Ti 1 − x Al 4 x /3 O 6 (0 ≤ x ≤ 0.1) ceramics are synthesized using the solid phase method, showing excellent microwave dielectric properties with ε r  = 14.05, Q × f = 144 500 GHz, and τ f  = −43 ppm/°C at x = 0.04. Rietveld refinements, based on the XRD data, reveal that the Li 2 Mg 3 Ti 1 − x Al 4 x /3 O 6 ceramics crystallize in the rock salt structure with Fm-3m space group. The relationship between the crystal structure and intrinsic microwave dielectric properties is studied in detail. The variation in the dielectric constant is related to ionic polarization and relative density. The quality factor (Q × f) demonstrates a strong correlation with lattice energy, relative density, and concentration of Ti 3+ . The variation of τ f is influenced by the bond thermal expansion coefficient and bond valence. The dielectric resonant antenna, manufactured from Li 2 Mg 3 Ti 0.96 Al 0.0533 O 6 -0.09TiO 2 ceramic with near-zero τ f , shows a bandwidth of 230 MHz at 7.40 GHz and a high radiant efficiency, which indicates that high-quality factor Li 2 Mg 3 Ti 0.96 Al 0.0533 O 6 ceramic has significant potential in relevant fields such as 5G and smart driving.