New dielectric material system of Mg0.95Co0.05TiO3 −Zn0.975Ca0.025TiO3 at microwave frequencies

Abstract: The microstructures and the microwave dielectric properties of the (1− x)Mg0.95Co0.05TiO3 − xZn0.975Ca0.025TiO3 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. Zn0.975Ca0.025TiO3 has dielectric a constant ɛ r ∼30, Q × f value∼45,000GHz, and a large positive τ f value∼30ppm/°C. Mg0.95Co0.05TiO3 has a high dielectric constant (ɛ r ∼16.8), high quality factor (Q × f value∼230,000 at 10GHz), and a negative τ f value (−54ppm/°C). The dielectric constant decreased from 29.1 to 18.36 when x changed from 0.9 to 0.3. In the x(Mg0.95Zn0.05Ti)O3 −(1− x)Zn0.975Ca0.025TiO3 system, the microwave dielectric properties can be effectively controlled by varying the x value. At 1200°C, 0.7Mg0.95Co0.05TiO3 −0.3 Zn0.975Ca0.025TiO3 had a dielectric constant (ɛ r ) of 22.6, a Q × f value of 57,000GHz, and a temperature coefficient of resonant frequency (τ f ) of 0ppm/°C. [Copyright &y& Elsevier]