A novel temperature-compensated microwave dielectric (1-x) (Mg_0.95Ni_0.05)TiO₃-xCa_0.6 La_0.8/3TiO₃ ceramics system

The microstructure and microwave dielectric properties of a (1-x)(Mg_0.95 Ni_0.05)TiO₃ -xCa_0.6La_0.8/3TiO₃ ceramics system have been investigated. The system was prepared using a conventional solid-state ceramic route. In order to produce a temperature-stable material, Ca_0.6La_0.8/3TiO₃ was added for a near-zero temperature coefficient (τ_f). With partial replacement of Mg²⁺ by Ni²⁺, the dielectric properties of the (1-x) (Mg_0.95Ni_0.05) TiO_3-xCa_0.6La_0.8/3TiO₃ ceramics can be promoted. The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. An excellent Q × f value of 118,000 GHz can be obtained for the system with x = 0.9 at 1325°C. For practical application, a dielectric constant (ε_r) of 24.61, a Q × f value of 102,000 GHz, and a temperature coefficient of resonant frequency (τ_f) of -3.6 ppm/°C for 0.85(Mg_0.95 Ni_0.05)TiO₃-0.15Ca_0.6La_0.8/3 TiO₃ at 1325°C are proposed. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance.