Sintering behavior and microwave dielectric properties of Sr_2CeO_4 ceramics doped with Li_2CO_3-Bi_2O_3

摘要

Microwave dielectric ceramics Sr_2CeO_4 + n wt% Li_2CO_3-Bi_2O_3 (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 Sr_2CeO_4 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 Sr_(2-)CeO_4 ceramics with dense structure and homogenous grains were obtained by adding lwt% LB. With LB content increasing, Q × f values would decrease because secondary-phase SrCeO_3 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 Li_2CO_3 increasing. Desirable performances of Sr_2CeO_4 + lwt% 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 Sr_2CeO_4-LB ceramics have a great potential for millimeter-wave applications.