MICROWAVE DIELECTRIC PROPERTIES OF (1-x)(Mg_(0.6)Zn_(0.4))_(0.95)Co_(0.05)TiO_3-xSrTiO_3 CERAMIC SYSTEM

摘要

The microstructures and the microwave dielectric properties of the (1-x)(Mg_(0.6)Zn_(0.4))_(0.95)Co_(0.05)TiO_3-xSrTiO_3 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. SrTiO_3 has dielectric properties of dielectric constant ε_r ～ 205, Q × f value ～ 4,200 GHz and a large positive τ_f value ～ 1700 ppm/°C. (Mg_(0.6)Zn_(0.4))_(0.95)Co_(0.05)TiO_3 possesses high dielectric constant (ε_r ～ 19.6), high quality factor (Q ×f value ～ 162,000 GHz) and negative τ_f value (-65 ppm/°C). By appropriately adjusting the x value in the (1-x)(Mg_(0.6)Zn_(0.4))_(0.95)Co_(0.05)TiO_3-xSrTiO_3 ceramic system, a near-zero τ_f value can be obtained. A new microwave dielectric material of 0.96((Mg_(0.6)Zn_(0.4))_(0.95)Co_(0.05)TiO_3-0.04SrTiO_3 possesses the excellent dielectric properties of a dielectric constant of 23.5, a Q × f value of 92,000 GHz and a τ_f value of -2.5 ppm/°C and can be utilized in microwave devices.