Low temperature sintering and microwave dielectric properties of MgNb2O6 ceramics.

The effects of co-doped CuO and B₂O₃ addition on the sintering temperature, microstructure and microwave dielectric properties of MgNb₂O₆ ceramics prepared with conventional solid-state route were investigated. When both CuO and B₂O₃ were added, the MgNb₂O₆ ceramics were not only sintered at 1000 °C but also improved the Qf value. MgNb₂O₆ ceramics can be well sintered to approach to 98.1% theoretical density with 2.0 wt.% CuO–B₂O₃ additive due to its liquid phase effect. With 2.0 wt.% CuO–B₂O₃, a dielectric constant of 21.5, a Qf value of 108,000(GHz) and a τ _f value of −44 ppm/°C of MgNb₂O₆ ceramics doped with CuO–B₂O₃ sintered at 1050 °C for 2 h are obtained. The variation of ε_r, Qf and τ _f were also explained based on the difference in microstructures. [ABSTRACT FROM AUTHOR]