New dielectric material system of Mg 0.95Co 0.05TiO 3 − Zn 0.975Ca 0.025TiO 3 at microwave frequencies

Abstract

The microstructures and the microwave dielectric properties of the (1 − x)Mg 0.95Co 0.05TiO 3 − xZn 0.975Ca 0.025TiO 3 ceramic system prepared using the conventional solid state method were investigated. In order to achieve a temperature-stable material, a method of combining a positive temperature coefficient material with a negative one studied. Zn 0.975Ca 0.025TiO 3 has dielectric a constant ɛ r ∼ 30, Q × f value ∼ 45,000 GHz, and a large positive τ f value ∼ 30 ppm/°C. Mg 0.95Co 0.05TiO 3 has a high dielectric constant ( ɛ r ∼ 16.8), high quality factor ( Q × f value ∼ 230,000 at 10 GHz), and a negative τ f value (−54 ppm/°C). The dielectric constant decreased from 29.1 to 18.36 when x changed from 0.9 to 0.3. In the x(Mg 0.95Zn 0.05Ti)O 3 − (1 − x)Zn 0.975Ca 0.025TiO 3 system, the microwave dielectric properties can be effectively controlled by varying the x value. At 1200 °C, 0.7Mg 0.95Co 0.05TiO 3 − 0.3 Zn 0.975Ca 0.025TiO 3 had a dielectric constant ( ɛ r ) of 22.6, a Q × f value of 57,000 GHz, and a temperature coefficient of resonant frequency ( τ f ) of 0 ppm/°C.