Pure Oxygen Atmosphere Sintering Behavior and Microwave Dielectric Properties of x(Mg_(0.96)Co_(0.04))TiO_3 - (1-x)SrTiO_3 Ceramics

摘要

The microstructures and the microwave dielectric properties of x(Mg_(0.96)Co_(0.04))TiO_3-(1-x)SrTiO_3 ceramics have been investigated by using pure oxygen atmosphere sintering. 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, Qxf value of ～ 4,200 and a large positive τ_f value of ～ 1,700 ppm/°C. Mg_(0.96)Co_(0.04)TiO_3 possesses high dielectric constant ε_r ～ 18, Qxf value of ~12,013 at 10 GHz and negative τ_f value of ～ -18 ppm/°C. By appropriately adjusting the x value in the x(Mg_(0.96)Co_(0.04))TiO_3-(1-x)SrTiO_3 ceramic system, a near zero τ_f value can be achieved. The experiments showed that with x = 0.94, a dielectric constant of about 21, the quality factor value of about 10,791 (at 9 GHz), the τ_f value 2.3 ppm/°C were obtained for 0.94(Mg_(0.96)Co_(0.04))TiO_3-(0.06)SrTiO_3 ceramics sintered at 1360°C for 6 h. The pure oxygen atmosphere sintering can also significantly lower the sintering temperature from 1450°C to 1360°C. Therefore, 0.94(Mg_(0.96)Co_(0.04))TiO_3-(0.06)SrTiO_3 ceramic system with pure oxygen atmosphere sintering may be suggested for application in communication devices.