Low temperature sintering and microwave dielectric properties of MgNb_2O_6 ceramics

摘要

The effects of co-doped CuO and B_2O_3 addition on the sintering temperature, microstructure and microwave dielectric properties of MgNb_2O_6 ceramics prepared with conventional solid-state route were investigated. When both CuO and B_2O_3 were added, the MgNb_2O_6 ceramics were not only sintered at 1000℃ but also improved the Qf value. MgNb_2O_6 ceramics can be well sintered to approach to 98.1% theoretical density with 2.0 wt.% CuO-B_2O_3 additive due to its liquid phase effect. With 2.0 wt.% CuO-B_2O_3, a dielectric constant of 21.5, a Qf value of 108,000(GHz) and a τ_f value of -44 ppm/℃ of MgNb_2O_6 ceramics doped with CuO-B_2O_3 sintered at 1050 ℃ for 2 h are obtained. The variation of ε_r, Qf and τ_f were also explained based on the difference in microstructures.