Sintering behavior and microwave dielectric properties of Sr₂CeO₄ ceramics doped with Li₂CO₃-Bi₂O₃

Microwave dielectric ceramics Sr₂CeO₄ + n wt% Li₂CO₃—Bi₂O₃ (LB) (1 ≤ n ≤ 4, L: B = x: y, weight ratio) were prepared by a traditional solid-state reaction method. The effects of LB additives on the phase formation, microstructure, sintering behavior, and microwave dielectric properties of Sr₂CeO₄ ceramics were investigated. The sintering temperature can be reduced obviously from 1270 to 950 °C because of the liquid phase formation of LB. Single-phase Sr₂CeO₄ ceramics with dense structure and homogenous grains were obtained by adding 1wt% LB. With LB content increasing, Q × f values would decrease because secondary-phase SrCeO₃ appeared in the ceramics. When the content of LB was fixed at 1 wt%, the sintering temperature and Q × f value would decrease simultaneously with the ratio of Li₂CO₃ increasing. Desirable performances of Sr₂CeO₄ + 1wt% LB ceramics: (ε_r = 14.36, Q × f = 102,023 GHz and τ_f =  − 66.42 ppm/°C, L:B = 2:8) and (ε_r = 13.56, Q × f = 70,109 GHz, τ_f =  − 64.17 ppm/°C, L:B = 8:2) can be achieved at 1075 °C and 950 °C, respectively, suggesting that Sr₂CeO₄–LB ceramics have a great potential for millimeter-wave applications.