Liquid phase sintering of (Zr,Sn)TiO4 microwave dielectric ceramics

The effect of CuO addition on the microstructures and the microwave dielectric properties of (Zr0.8,Sn0.2)TiO4 ceramics have been investigated. It is found that low-level doping of ZnO (1 wt%) and CuO (up to 2 wt%) can significantly improve the density and dielectric properties of (Zr0.8,Sn0.2)TiO4 ceramics. (Zr0.8,Sn0.2)TiO4 ceramics with additives could be sintered to a theoretical density higher than 96% at 1220°C, due to the liquid phase effect of CuO addition, as observed by scanning electron microscopy (SEM). A secondary phase was not observed at the level of 0.5–2 wt% CuO addition. The dielectric constant (εr). While the temperature coefficient of resonant frequency (τf) were not significantly affected, the unloaded quality factors Q were effectively promoted by CuO addition. An εr value of 38, Q·f value of 50000 (at 7 GHz), and τf value of 3 ppm/°C were obtained for 1 wt% ZnO doped (Zr0.8,Sn0.2)TiO4 ceramics with 1 wt% CuO addition sintered at 1220°C.