Microwave dielectric properties of (1− x)(Mg0.95Co0.05)TiO3–xCa0.6La0.8/3TiO3 ceramics with V2O5 addition

Abstract: The microstructures and the microwave dielectric properties of the (1− x)(Mg0.95Co0.05)TiO3–xCa0.6La0.8/3TiO3 ceramic system were investigated. In order to achieve a temperature-stable material, we studied a method of combining a positive temperature coefficient material with a negative one. Ca0.6La0.8/3TiO3 has dielectric properties of dielectric constant ε r ∼109, Q × f value∼17,600GHz and a large positive τ f value∼213ppm/°C. (Mg0.95Co0.05)TiO3 ceramics possesses high dielectric constant (ε r ∼16.8), high quality factor (Q × f value∼230,000GHz), and negative τ f value (−54ppm/°C). As the x value varies from 0.1 to 0.8, (1− x)(Mg0.95Co0.05)TiO3–xCa0.6La0.8/3TiO3 ceramic system has the dielectric properties as follows: 21.55< ε r <75.44, 21,000< Q × f <90,000 and −10< τ f <140. By appropriately adjusting the x value in the (1− x)(Mg0.95Co0.05)TiO3–xCa0.6La0.8/3TiO3 ceramic system, zero τ f value can be achieved. With x =0.15, a dielectric constant ε r ∼25.78, a Q × f value∼84,000GHz (at 9GHz), and a τ f value∼2ppm/°C were obtained for 0.85(Mg0.95Co0.05)TiO3–0.15Ca0.6La0.8/3TiO3 ceramics sintered at 1400°C for 4h. For practical application in communication systems, it is desirable to be able to sinter at lower temperatures. Therefore, V2O5 was as a sintering aid for lowering the sintering temperature of0.85(Mg0.95Co0.05)TiO3–0.15Ca0.6La0.8/3TiO3 ceramics. At the same time, the 0.85(Mg0.95Co0.05)TiO3–0.15Ca0.6La0.8/3TiO3 ceramic system with 0.5wt% V2O5 can be obtained good properties at the microwave frequencies for 1200°C. [Copyright &y& Elsevier]