Temperature compensating microwave dielectric based on the (Mg _0.95Ni _0.05)TiO ₃-(La _0.5Na _0.5)TiO ₃ ceramic system

The microstructures and microwave dielectric properties of the novel temperature-compensated composite ceramic (1-x)(Mg _0.95Ni _0.05)TiO ₃-x(La _0.5Na _0.5)TiO ₃ were investigated. Dense and mixed phase samples were produced in the range of 0.05≤x≤0.9. When the x value increased, the quality factor (Q × f) decreased nonlinearly while the dielectric constant (ε _r) steadily increased almost linearly due to the compensation effect. The temperature coefficient of resonant frequency (τ _f) was remarkably improved with an increase of (La _0.5Na _0.5)TiO ₃ content. With x=0.13, a dielectric constant (ε _r) of 23.22, a Q × f value of 86,500 GHz, and a τ _f value of 2.8 ppm/°C was obtained for 0.87(Mg _0.95Ni _0.05)TiO ₃-0.13(La _0.5Na _0.5)TiO ₃ ceramics sintered at 1275°C for 4 h. Moreover, a band-pass filter with traditional hairpin resonators with a center frequency of 2.4 GHz was designed and fabricated using the proposed dielectric ceramic to study its performance.