Improved high-Q microwave dielectric resonator using ZnO and WO3-doped Zr0.8Sn0.2TiO4 ceramics

The effect of WO3 addition on the microstructures and the microwave dielectric properties of Zr0.8Sn0.2TiO4 ceramics have been investigated. It is found that low-level doping of ZnO (1 wt%) and WO3 (up to 1 wt%) can significantly improve the density and dielectric properties of Zr0.8Sn0.2TiO4 ceramics. Zr0.8Sn0.2TiO4 ceramics with additives could be sintered to a theoretical density higher than 98% at 1340°C. Second phases were not observed at the level of 0.25–1 wt% WO3 addition. The dielectric constant (ϵr) and the temperature coefficient of resonant frequency (τf) were not significantly affected, while the unloaded quality factors Q were effectively promoted by WO3 addition. An ϵr value of 37.8, Q·f value of 61,000 (at 7 GHz), and τf value of −3.9 ppm/°C were obtained for 1 wt% ZnO-doped Zr0.8Sn0.2TiO4 ceramics with 0.25 wt% WO3 addition sintered at 1340°C.