Crystal structure and dielectric properties of La(Mg_0.5Ti _0.5)O₃-Ca_0.8Sm_0.4/3TiO₃ solid solution system at microwave frequencies

The crystal structure and the dielectric properties of (1 - x)La(Mg _0.5Ti_0.5)O₃-xCa_0.8Sm _0.4/3TiO₃ ceramics have been investigated. Ca _0.8Sm_0.4/3TiO₃ was employed as a τ_f compensator and was added to La(Mg_0.5Ti _0.5)O₃ to achieve a temperature-stable material. The formation of (1 - x)La(Mg_0.5Ti_0.5)O₃-xCa _0.8Sm_0.4/3TiO₃ solid solutions were confirmed by the XRD results and the measured lattice parameters for all compositions. The dielectric properties are strongly correlated to the sintering temperature and the compositional ratio of the specimens. Although the ε_r of the specimen could be boosted by increasing the amount of Ca_0.8Sm _0.4/3TiO₃, it would instead render a decrease in the Q × f. The τ_f value is strongly correlated to the compositions and can be controlled by the existing phases. A new microwave dielectric material 0.45La(Mg_0.5Ti_0.5)O ₃-0.55Ca_0.8Sm_0.4/3TiO₃, possessing a fine combination of microwave dielectric properties with an ε_r of 47.83, a Q × f of 26,500 GHz (at 6.2 GHz) and a τ_f of -1.7 ppm/°C, is proposed as a very promising candidate material for today's 3G applications.