Investigation of (1-x)(Mg0.6Zn0.4)0.95Co0.05TiO3–xSrTiO3Microwave Dielectrics

The microwave dielectric properties and microstructures of (1-x)(Mg0.6Zn0.4)0.95Co0.05TiO3–xSrTiO3 ceramics were investigated using a network analyzer and scanning electron microscope (SEM). In order to achieve a temperature-stable material, we used a method of combining a positive-temperature-coefficient material with a negative one. SrTiO3 has a large positive temperature coefficient of resonant frequency (τf) of 1,700 ppm/°C. (Mg0.6Zn0.4)0.95Co0.05TiO3 possesses a negative temperature coefficient of resonant frequency of -65 ppm/°C. The dielectric constant and density increase with increasing SrTiO3 content. By appropriately adjusting x in the (1-x)(Mg0.6Zn0.4)0.95Co0.05TiO3–xSrTiO3 ceramic system, a near-zero τf value can be obtained. A new microwave material of 0.96(Mg0.6Zn0.4)0.95Co0.05TiO3–0.04SrTiO3 exhibits excellent dielectric properties including of a dielectric constant of 23.5, a Q ×f value of 92,000 GHz, and a temperature coefficient of resonant frequency of -2.5 ppm/°C, and can be utilized in the fabrication of microwave devices.