Characterization and dielectric behavior of CuO-doped ZnTa2O6 ceramics at microwave frequency

The effects of CuO addition on the microstructures and microwave dielectric properties of ZnTa₂O₆ ceramics were investigated. CuO was selected as a liquid-phase sintering aid to lower the sintering temperature of ZnTa₂O₆ ceramics. With CuO addition, the sintering temperature of ZnTa₂O₆ can be effectively reduced from 1350 to 1230 °C. The crystalline phase exhibited no phase difference and no second phase was detected at low addition levels (0.25-1 wt.%). The quality factors Q × f were strongly dependent upon the CuO concentration. A Q × f value of 65,500 GHz was obtained for specimen with 0.25 wt.% CuO addition at 1230 °C. For all levels of CuO concentration, the relative dielectric constants were not significantly different and ranged from 34.2 to 35.7. Tunable temperature coefficient of resonant frequency (τ_f) can be adjusted to zero by appropriately turning the CuO content.