Structure and dielectric properties of ZnO and Nb2O5 doped BaO-TiO2 system microwave ceramics

The microwave dielectric properties and microstructure of BaTi_4.3ZnyO_9.6+y +0.02 mol% SnO₂+0.01 mol% MnCO_3+x mol% Nb₂O₅(x=0–0.05, y=0–0.08) system ceramics were studied as a function of the amount of ZnO and Nb₂O₅ doped. Addition of (y=0–0.05) ZnO and (x=0–0.025) Nb₂O₅ enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant ɛ _r and quality factor Q(=1/tan δ) of the system due to the substitution of Ti⁴⁺ ions with incorporating Zn²⁺ and Nb⁵⁺ ions, which was analyzed by the reaction ZnO+Nb₂O₅+ 3 Ti_Ti ^x → Zn_Ti+ 2Nb_Ti ^·+3TiO₂. When the system doped with (y=0.05) ZnO and (x=0.025) Nb₂O₅ were sintered at 1 160 °C for 6 h, the ɛ _r , Q _f0 value and τ _f were 36.5, 42 000 GHz, and+1.8 ppm/°C, respectively, at 5 GHz. Funded by the Natural Science Foundation of Tianjin (No. 06YFJMJC01000)