Optimizing microwave dielectric properties through structural tuning in Mg2+xTi1-xO4 ceramics

This study systematically explores how variations in crystal structural parameters affect the microwave dielectric properties of the Mg 2+ x Ti 1- x O 4 (x = 0.04–0.13) ceramics. XRD and Raman analysis reveal that Mg 2+ x Ti 1- x O 4 ceramics ( x  = 0.04−0.1) crystallize into a spinel-type structure with a space group of Fd-3m, while a second phase of MgTiO 3 is observed at x  = 0.13. The variation in dielectric constant is primarily associated with bond covalency, and changes in bond energy have a significant impact on the variation of τ f . Non-intrinsic factors, such as grain size and relative density, show a marked dependence on the variation in Q × f , while intrinsic factors, particularly lattice energy, play a decisive role on its change. The intrinsic dielectric loss obtained in the far-infrared range is lower than the dielectric loss in the microwave frequency range, indicating that the Mg 2+ x Ti 1- x O 4 ceramics still have potential for further enhancement of Q × f , such as by reducing the influence of non-intrinsic factors. Mg 2+ x Ti 1- x O 4 ceramics at x  = 0.1 exhibit the optimal microwave dielectric properties with ε r  = 14.15, Q × f  = 211457 GHz, τ f  = −48.3 ppm/°C.