Microstructure and microwave dielectric characteristics of (Zn1−xCox)ZrNb2O8 ceramics

The (Zn1−xCox)ZrNb2O8 (x = 0.1, 0.2, 0.3, 0.4) ceramics were synthesized by the conventional solid-state reaction route and sintered in the temperature range of 1160–1320 °C. The microstructure and microwave dielectric properties were investigated systematically. The X-ray diffraction results showed that the (Zn1−xCox)ZrNb2O8 ceramics exhibited a single monoclinic structure. The variation trend of dielectric constant (εr) was in accordance with variation trend of relative density. The Qf value decreased with the decrease of the packing fraction. The temperature coefficient of resonant frequency (τf) moved towards positive due to the increase of B-site bond valence. In conclusion, the excellent microwave dielectric properties were obtained for Zn0.9Co0.1ZrNb2O8 ceramics sintered at 1240 °C for 4 h: εr = 27.93, Q × f = 68,615 GHz (where f = 6.95 GHz), and τf = −61.94 × 10−6/°C.