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 (e r ) 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 (τ f ) 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: e r = 27.93, Q × f = 68,615 GHz (where f = 6.95 GHz), and τ f = −61.94 × 10−6/°C.